Computer Simulation of Light-Duty
Vehicle Technologies for Greenhouse
Gas Emission Reduction in the
2020-2025 Timeframe
&EPA
United States
Environmental Protection
Agency
-------
Computer Simulation of Light-Duty
Vehicle Technologies for Greenhouse
Gas Emission Reduction in the
2020-2025 Timeframe
Assessment and Standards Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
Prepared for EPA by
Ricardo, Inc.
and
Systems Research and Applications Corporation (SRA)
EPA Contract No. EP-C-11-007
Work Assignment No. 0-12
NOTICE
This technical report does not necessarily represent final EPA decisions or
positions. It is intended to present technical analysis of issues using data
that are currently available. The purpose in the release of such reports is to
facilitate the exchange of technical information and to inform the public of
technical developments.
United States
Environmental Protection
Agency
EPA-420-R-11-020
December 2011
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Computer Simulation of LDV Technologies for GHG Emission Reduction in the 2020-2025 Timeframe
COMPUTER SIMULATION OF LIGHT-DUTY VEHICLE TECHNOLOGIES FOR
GREENHOUSE GAS EMISSION REDUCTION IN THE 2020-2025 TIMEFRAME
EXECUTIVE SUM MARY
Ricardo, Inc. was subcontracted by Systems Research and Applications Corporation (SRA), a
wholly owned subsidiary of SRA International, Inc., under contract to the United States
Environmental Protection Agency (EPA) to assess the effectiveness of future light duty vehicle
(LDV) technologies on future vehicle performance and greenhouse gas (GHG) emissions in the
2020-2025 timeframe. GHG emissions are a globally important issue, and the EPA's Office of
Transportation and Air Quality (OTAQ) has been chartered with examining the GHG emissions
reduction potential of LDVs, including passenger cars and light-duty trucks. This program was
performed between October 2009 and November 2011.
The scope of this project was to execute an independent and objective analytical study of LDV
technologies likely to be available within the 2020-2025 timeframe, and to develop a data
visualization tool to allow users to evaluate the effectiveness of LDV technology packages for
their potential to reduce GHG emissions and their effect on vehicle performance. This study
assessed the effectiveness of a broad range of technologies including powertrain architecture
(conventional and hybrid), engine, transmission, and other vehicle attributes such as engine
displacement, final drive ratio, vehicle weight, and rolling resistance on seven light-duty vehicle
classes. The methodology used in this program surveyed the broad design space using robust
physics-based modeling tools and then generated a computationally efficient response surface
to enable extremely fast surveying of the design space within a data visualization tool. During
this effort, quality assurance checks were employed to ensure that the simulation results were a
valid representation of the performance of the vehicle. Through the use of the data visualization
tool, the users can query the design space on a real time basis while capturing interactions
between technologies that may not be identified from individual simulations.
This report documents the work done on the program "Computer Simulation of Light Duty
Vehicle Technologies for Greenhouse Gas Emission Reduction in the 2020-2025 Timeframe".
This work has included identifying and selecting technologies for inclusion in the study,
developing and validating baseline models, and developing the data visualization tool.
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TABLE OF CONTENTS
1. INTRODUCTION 8
2. OBJECTIVES 9
3. BACKGROUND 9
3.1 Study Background 9
3.2 Ground Rules for Study 10
3.3 Technology Package Selection Process 11
3.4 Complex Systems Modeling Approach 12
3.5 Data Visualization Tool 13
4. TECHNOLOGY REVIEW 13
4.1 Advanced Engine Technologies 13
4.1.1 Advanced Valvetrains 14
4.1.1.1 Cam-Profile Switching Valvetrain 14
4.1.1.2 Digital Valve Actuation Valvetrain 14
4.1.2 Direct Injection Fuel Systems 17
4.1.3 Boosting System 17
4.1.4 Other Engine Technologies 18
4.2 Engine Configurations 19
4.2.1 Stoichiometric Dl Turbo 19
4.2.2 Lean-Stoichiometric Switching 21
4.2.3 EGRDI Turbo 22
4.2.4 Atkinson Cycle 23
4.2.5 Advanced Diesel 23
4.2.6 Fueling Map Development Examples 24
4.2.6.1 EBDI®to EGR Dl Turbo 24
4.2.6.2 Contemporary to Future Atkinson 25
4.3 Hybrid Technologies 26
4.3.1 Micro Hybrid: Stop-Start 26
4.3.2 P2 Parallel Hybrid 26
4.3.3 Input Powersplit 27
4.4 Transmission Technologies 27
4.4.1 Automatic Transmission 28
4.4.2 Dual Clutch Transmission (DCT) 28
4.4.3 Launch Device: Wet Clutch 29
4.4.4 Launch Device: Dry Clutch Advancements 29
4.4.5 Launch Device: Multi-Damper Torque Converter 30
4.4.6 Shifting Clutch Technology 30
4.4.7 Improved Kinematic Design 30
4.4.8 Dry Sump 31
4.4.9 Efficient Components 31
4.4.10 Super Finishing 31
4.4.11 Lubrication 31
4.5 Vehicle Technologies 31
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4.5.1 Intelligent Cooling Systems 31
4.5.2 Electric Power Assisted Steering 32
5. TECHNOLOGY BUNDLES AND SIMULATION MATRICES 32
5.1 Technology Options Considered 32
5.2 Vehicle configurations and technology combinations 32
6. VEHICLE MODEL 35
6.1 Baseline Conventional Vehicle Models 35
6.2 Baseline Hybrid Vehicle Models 36
6.3 Engine Models 36
6.3.1 Warm-up Methodology 38
6.3.2 Accessories Models 38
6.4 Transmission Models 40
6.5 Torque Converter Models 42
6.6 Final Drive Differential Model 42
6.7 Driver Model 43
6.8 Hybrid Models 43
7. MODEL VALIDATION RESULTS 47
7.1 Validation Cases and 2010 Baseline Vehicle Models 47
7.2 Nominal Runs 48
8. COMPLEX SYSTEMS MODEL VALIDATION 48
8.1 Evaluation of Design Space 48
8.2 Response Surface Modeling 50
9. RESULTS 50
9.1 Basic Results of Simulation 50
9.2 Design Space Query 50
9.3 Exploration of the Design Space 51
9.4 Identification and Use of the Efficient Frontier 51
10. RECOMMENDATIONS FOR FURTHER WORK 56
11. CONCLUSIONS 56
12. ACKNOWLEDGEMENTS 57
13. REFERENCES 58
APPENDICES 60
Appendix 1, Abbreviations 60
Appendix 2, Assessment of Technology Options 61
Appendix 3, Baseline Vehicle Parameters and Runs Results 63
Appendix 4, Output Factors for Study 64
Appendix 5, Nominal Runs Results 65
ATTACHMENT A 69
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LIST OF FIGURES
Figure 3.1: Technology package selection process 11
Figure 4.1: Honda's VTEC cam profile switching system 15
Figure 4.2: Expected BSFC benefit from CPS system over typical engine operating map 15
Figure 4.3: INA UniAir digital valve actuation system 16
Figure 4.4: Expected BSFC benefit from DVA system over typical engine operating map 16
Figure 4.5: General Motors two-stage turbo transient performance 18
Figure 4.6: Typical region of fuel enrichment in stoichiometric Dl engines, eliminated through
use of a water-cooled exhaust manifold 20
Figure 4.7: 2.CM! General Motors SIDI two-stage boosted engine BSFC map 21
Figure 4.8: Zone of lean operation for Lean-Stoichiometric Dl Turbo engine 22
Figure 4.9: BSFC map (in g/kW-h) for EBDI® engine with EGR 24
Figure 4.10: BSFC map (in g/kW«h) for Toyota Prius engine 25
Figure 4.11: Comparison of Automatic and DCT Transmission Efficiencies 29
Figure 4.12: Typical transverse wet clutch DCT arrangement 30
Figure 6.1: MSC.EasyS conventional vehicle model 36
Figure 6.2: Change in BSFC resulting from cylinder heat loss 38
Figure 6.4: Comparison of CVT and optimized DCT gear ratios overdrive cycle 41
Figure 6.5: Comparison of shift activity for traditional and optimized shifting strategies 42
Figure 6.6: 2007 Camry motor-inverter efficiency contour map 44
Figure 6.7: High level state flow diagram for the hybrid control strategy 44
Figure 6.8: Best BSFC curve superimposed on fueling map 46
Figure 6.9: Hybrid powertrain energy supervisory strategy 46
Figure 9.1: Design Space Query screen in Data Visualization Tool 52
Figure 9.2: Design Space Analysis screen in Data Visualization Tool 52
Figure 9.3: Full Size Car Design Space Analysis example 53
Figure 9.4: Full Size Car Design Space Analysis example 53
Figure 9.5: Full Size Car Design Space Analysis example 54
Figure 9.6: Standard Car design space analysis example comparing powertrains with EGR Dl
Turbo engine 54
Figure 9.7: Full design space example showing all seven vehicle classes using Stoichiometric
Dl Turbo engine and advanced automatic transmission with varying vehicle mass and engine
displacement 55
Figure 9.8: Efficient Frontier screen of Data Visualization Tool with example plot 55
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Computer Simulation of LDV Technologies for GHG Emission Reduction in the 2020-2025 Timeframe
LIST OF TABLES
Table 5.1: Engine technology package definition 33
Table 5.2: Hybrid technology package definition 33
Table 5.3: Transmission technology package definition 33
Table 5.4: Baseline and Conventional Stop-Start vehicle simulation matrix 34
Table 5.5: P2 and Input Powersplit hybrid simulation matrix 34
Table 6.1: Vehicle classes and baseline exemplar vehicles 36
Table 6.3: Accessory loads for conventional stop-start and P2 hybrids 39
Table 6.4: Mechanical cooling fan loads for LOT and LHDT 39
Table 6.5: Transmission gear ratios for six-speed and eight-speed transmissions 40
Table 7.1: Validation vehicle fuel economy performance 47
Table 8.1: Continuous input parameter sweep ranges with conventional powertrain 49
Table 8.2: Continuous input variable ranges for P2 and Powersplit hybrid powertrains 49
Table A3.1: Baseline Vehicle Parameters and Runs Results 63
Table A5.1: Nominal Runs Results 66
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1. INTRODUCTION
Ricardo was subcontracted by Systems Research and Applications Corporation (SRA), a wholly
owned subsidiary of SRA International, Inc., under contract to the United States Environmental
Protection Agency (EPA) to assess the effectiveness of future light duty vehicle (LDV)
technologies on future vehicle performance and greenhouse gas (GHG) emissions in the 2020-
2025 timeframe. GHG emissions are a globally important issue, and the EPA's Office of
Transportation and Air Quality (OTAQ) has been chartered with examining the GHG emissions
reduction potential of LDVs, including passenger cars and light-duty trucks.
SRA is a company of over 7,000 staff dedicated to solving complex problems of global
significance for government organizations serving the civil government, global health, and
national security markets. SRA's Air Programs and Climate Change Account works extensively
with OTAQ and other EPA offices on regulatory and voluntary programs to reduce air pollution
and address climate change.
SRA and Ricardo worked closely with the EPA team on nearly every technical and contractual
issue.
The team at EPA OTAQ included the following staff members:
• Matt Brusstar, Director, Advanced Powertrain Center, Testing and Advanced
Technology Division
• Jeff Cherry, Staff Engineer, Light Duty Vehicles and Small Engine Center, Assessment
and Standards Division
• Ann Chiu, Contract Project Officer, Data Analysis and Information Center, Compliance
Division
• Ben Ellies, Staff Engineer, Climate Analysis and Strategies Center, Transportation and
Climate Division
• Joe McDonald, Senior Engineer, Fuels Center, Assessment and Standards Division
In addition to the SRA-Ricardo team working for EPA, other stakeholders for the program
included the International Council on Clean Transportation (ICCT) and the California Air
Resources Board (ARE). ICCT contributed funding for the early portion of the study in
collaboration with ARE. The Advisory Committee provided advice to EPA, and included the
following representatives from ICCT and ARE:
• Steven Albu, Assistant Division Chief, ARE
• Anup Bandivedakar, Senior Researcher, ICCT
• John German, Senior Fellow and Program Director, ICCT
• Paul Hughes, Manager, ARE
Ricardo, Inc., is the US division of Ricardo pic., a global engineering consultancy with nearly
100 years of specialized engineering expertise and technical experience in engines,
transmissions, and automotive vehicle research and development. This program was performed
between October 2009 and November 2011.
The scope of the program was to execute an independent and objective analytical study of LDV
technologies likely to be available for volume production in the 2020-2025 timeframe, and to
develop a data visualization tool to allow users to evaluate the effectiveness of LDV technology
packages for their potential to reduce GHG emissions. An assessment of the effect of these
technologies on LDV cost was beyond the scope of this study.
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This work was done in collaboration with EPA, and the approach included the following:
• Activities funded by ICCT
o Identify a large set of future technologies that could improve LDV GHG
emissions.
o Assess these technologies for potential benefit and ability to be commercialized
by the 2020-2025 timeframe.
o Reduce this large set to the technologies selected for further study in this
program.
• Activities funded by EPA:
o Extrapolate selected technologies to their expected performance and efficiency
levels in the 2020-2025 timeframe.
o Conduct detailed simulation of the technologies over a large design space,
including a range of vehicle classes, powertrain architectures, engine designs,
and transmission designs, as well as parameters describing these configurations,
such as engine displacement, final drive ratio, and vehicle rolling resistance.
o Interpolate the results over the design space using a functional representation of
the responses to the varied model input factors.
o Develop a Data Visualization Tool to facilitate interrogation of the simulation
results over the design space.
2. OBJECTIVES
The goal of this technical program has been to objectively evaluate the effectiveness and
performance of a large LDV design space with powertrain technologies likely to be available in
the 2020-2025 timeframe, and thereby assess the potential for GHG emissions reduction in
these future vehicles while also understanding the effects of these technologies on vehicle
performance.
3. BACKGROUND
3.1 Study Background
The EPA has an interest in improving the environmental performance and efficiency of cars,
trucks, buses, and transportation systems to protect and improve public health, the
environment, and quality of life. Additionally, reduction of GHG emissions—emphasizing carbon
dioxide (CO2)—is an increasing priority of national governments and other policymakers
worldwide.
This program builds on the work done earlier by Perrin Quarles Associates (PQA, now part of
SRA) and Ricardo in 2007-2008 to assess the potential effectiveness of GHG-reducing
technologies in LDVs in the 2010-2017 timeframe (Ricardo and PQA, 2008). The earlier
program was also funded by EPA and looked at a series of specific LDV configurations and
from these assessed the benefits.
The purpose of this study is to define and evaluate potential technologies that may improve
GHG emissions in LDVs in the 2020-2025 timeframe. These technologies represent a mixture
of future mainstream technologies and some emerging technologies for the study timeframe.
For this program, however, a large design space was comprehensively examined so that
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broader conclusions could be drawn about these technologies that could lead to benefits to
GHG emissions reduction.
3.2 Ground Rules for Study
Several ground rules for the study were agreed at the beginning of the program to bound the
design space considered in the study. These ground rules identified content that should be
included in the study as well as content that should be excluded.
Some examples of the ground rules include the following items for the technology assessment:
• Seven vehicle classes will be included, as described below.
• LDV technologies must have the potential to be commercially deployed in 2020-2025. .
• Vehicle sizes, particularly footprint and interior space, for each class will be largely
unchanged from 2010 to 2020-2025.
• Hybrid vehicles will use an advanced hybrid control strategy, focusing on battery state of
charge (SOC) management, but not at the expense of drivability.
• Vehicles will use fuels that are equivalent to either 87 octane pump gasoline or 40
cetane pump diesel.
• 2020-2025 vehicles will meet future California LEV III requirements for criteria
pollutants, which are assumed to be equivalent to current SULEV II (or EPA Tier 2 Bin 2)
levels.
• Ricardo would be allowed to use Ricardo proprietary data and expertise to assess
technologies and develop the models, as this allowed the technologies to be assessed
more comprehensively than if only publicly available data were used. Ricardo
confidential business information relevant to the execution of the program was shared
with EPA for the purposes of allowing an external audit of the model inputs developed
for the program.
• Due to the multiple designs that manufacturers may realize for any given advanced
technology, the effect of technologies on overall vehicle mass is not incorporated directly
in the Easy5 models. Instead, the model makes the overt simplifying assumption that all
technologies are mass-neutral. The end-user has the flexibility to incorporate their own
assumptions about mass reduction from advanced technologies when exploring the
design space with the Data Visualization Tool.
• Similarly, other road load reductions such as aerodynamic drag and rolling resistance
reduction were addressed as input variables within the complex systems modeling
approach.
Likewise, EPA, along with input from the Advisory Committee agreed for this program that the
technology assessment should exclude the following:
• Charge-depleting powertrains, such as plug-in hybrid electric vehicles (PHEV) or battery
electric vehicles (BEV)1.
• Fuel cell power plants for fuel cell-electric vehicles (FCEV).
• Non-reciprocating internal combustion engines (ICE) or external combustion engines.
• Manual transmissions and automated manual transmissions (AMT) with a single clutch.
• Kinetic energy recovery systems (KERS) other than battery systems.
1 While modeling of vehicles with increased electrification would be beneficial, the highest priority was
given to vehicle architectures determined most likely to be present in higher volumes during the 2020-
2025 time frame. Due to resource limitations, PHEVs and BEVs were considered outside the scope of
this study and left as candidates for follow-up modeling work.
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• Intelligent vehicle to vehicle (V2V) and vehicle to infrastructure (V2I) optimization
technology.
• Bottoming cycles, such as organic Rankine cycles, for energy recovery.
• Vehicle safety systems or structures will not be explicitly modeled for vehicles. A full
safety analysis of the technologies presented in this report is beyond the scope of this
study.
The seven vehicle classes considered in this study are the following, with a currently available
example vehicle given for each class:
1. Small (B-class) Car, such as the Toyota Yaris
2. Standard (D-class) Car, such as the Toyota Camry
3. Small Multi-Purpose Vehicle (MPV), such as the Saturn Vue
4. Full Sized Car, such as the Chrysler 300
5. Large MPV, such as the Dodge Grand Caravan
6. Light-Duty Truck (LOT), such as the Ford F150
7. Light Heavy-Duty Truck (LHDT), such as the General Motors HD3500
3.3 Technology Package Selection Process
The program team used the process shown in Figure 3.1 to identify the technology options
listed in Appendix 2, Assessment of Technology Options, to the set described in Chapter 4,
Technology Review, and integrated into the technology bundles described in Chapter 5,
Technology Bundles and Simulation Matrices.
Technology
Identification
Ricardo
Subject
Matter
Expert
Assessment
EPA Review
&
Technology
Discussion
Technology
Package
Selection
Figure 3.1: Technology package selection process.
The program team first developed a comprehensive list of potential technologies shown in
Appendix 2 that could be in use on vehicles in the study timeframe, 2020-2025. These
technologies were grouped by subject area, such as transmissions, engines, or vehicle, and
given to Ricardo subject matter experts (SMEs) for assessment and evaluation. These SME
assessments were then reviewed with EPA, who also sought input from the Advisory
Committee. Together, the program team determined which technologies would be included
once they were evaluated qualitatively against the following criteria for further consideration:
• Potential of the technology to improve GHG emissions on a tank to wheels basis
• State of development and commercialization of the technology in the 2020-2025
timeframe
• Current (2010) maturity of the technology
The technology options selected were then put together into technology packages for use in the
vehicle performance simulations. An additional consideration was how the inclusion of the
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technology would affect simulation matrices presented in Section 5.2, particularly the effect on
the overall number of simulations needed.
3.4 Complex Systems Modeling Approach
Complex systems modeling (CSM) is an objective, scientific approach that supports high-level
decision making when there are a large number of factors to consider that influence the
outcome, as with LDV development for vehicle performance and GHG emissions reduction.
A vehicle is made up of interrelated components and subsystems, which combined make up a
system that by definition provides functionality greater than the sum of its parts. An automotive
system like a vehicle may be defined as a "complex system" based upon the number of
interrelated, interconnected, and interwoven elements and interfaces requiring a great deal of
information to specify (Kinnunen, 2006). An important concept associated with complex systems
is the property of "emergence". In this context it means that there may be collective behavior of
the components and subsystems along with the system's response to its environment that are
not predictable or linear in response to changes to the individual behavior of each part.
A number of interdisciplinary scientific efforts have led to the development of "complex systems
theory", which seeks to overcome the limitations of reductionist approaches through the
development of tools and models that are able to capture emergence and other behavior of
complex systems (McCarthy, et a/., 2000). Supplementing the use of complex systems theory is
the application of the system engineering process model, which dictates proceeding from the
general to the detailed—a top down approach—and observes the principle of creation and
selection of alternatives. These theories and principles have been developed into a
methodology that utilizes physics-based modeling and simulation in order to enable quantitative
analysis over a multidimensional design space along with advanced visualization techniques in
order to understand the results (Biltgen, et a/., 2006). Ricardo has incorporated this
methodology, now referred to as "complex system modeling (CSM) into its consulting practice
on previous projects (Luskin, 2010).
In this program, many combinations of technologies were used to generate detailed results that
were abstracted and made accessible through a Data Visualization Tool described in
Section 3.5. To be objective, performance metrics were identified by EPA and the Advisory
Committee; these metrics were outputs of the vehicle performance simulation effort and
characterize key vehicle attributes. To be scientific, the performance simulations use a physics-
based modeling approach for detailed simulation of the vehicle.
The design of experiments (DoE) approach surveys the design space in a way that extracts the
maximum information using a limited budget of simulation runs. The purpose of the DoE
simulation matrix was to efficiently explore a comprehensive potential design space for LDVs in
the 2020-2025 timeframe. The simulation matrix was designed to generate selected
performance results over the selected drive cycles, such as fuel consumption or acceleration
times.
A statistical analysis was used to correlate variations in the input factors to variations in the
output factors. Because of the complex nature of the LDV configurations and constituent
technology packages, a neural network approach was used to quantify the relationships
between input and output factors over the design space explored in the simulations. The result
of this analysis was a set of response surface models (RSM) that represent in simplified form
the complex relationships between the input and output factors in the design space.
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3.5 Data Visualization Tool
The Data Visualization Tool allows the user to efficiently assess the effects of various
combinations of future technologies on GHG emissions and other vehicle performance metrics.
The tool allows the user to query the RSM and investigate options leading to equivalent GHG
emissions levels. A separate User Guide for the Data Visualization Tool will be released with the
tool and will provide more information on how to use the tool to access the results.
The Data Visualization Tool uses the RSM set generated by the Complex Systems approach to
represent the vehicle performance simulation results over the design space. These simulations
cover multiple variations of vehicle configuration, including several combinations of advanced
powertrain and vehicle technologies in the seven LDV classes. Vehicle configurations with
unacceptable performance, such as combined fuel economy below a certain threshold or
acceleration times longer than some benchmark value, can be excluded from further study.
The tool samples vehicle configurations from a selected subset of the design space by using
Monte Carlo type capabilities to pick input parameter values from a uniform distribution. Defining
selected portions of the design space and plotting the results visualizes the effect of these
parameters on vehicle fuel economy and performance, allowing trade off analysis via
constraints setting to be performed over a wide design space representing the 2020-2025
technologies as applied.
4. TECHNOLOGY REVIEW
Following the process outlined above in Section 3.3, Technology Package Selection Process, a
broad list of potential technologies was identified for consideration in the study and then
narrowed to a subset for inclusion in the study. The technologies in this subset are described in
this chapter.
In the study timeframe of 2020-2025, spark-ignited (SI) engines are projected to continue to be
the dominant powertrain in the U.S. LDV market, especially since the efficiency of SI engines is
expected to approach the efficiency of compression ignition (Cl, or diesel) engines at the
required 2020-2025 emissions levels. Diesel engines are also included as they are still
expected to be present in the study timeframe, especially in the heavier vehicle classes.
The first two sections of this chapter therefore describe the technologies expected to appear in
future engines generally and in the specific engine configurations considered in the study,
respectively. The other sections in this chapter describe the transmission and driveline, vehicle,
and hybrid system technologies that were included in the overall design space of the study. The
implementation of these technologies in the vehicle performance models is described in
Chapter 6, Vehicle Model.
4.1 Advanced Engine Technologies
The primary challenge for advanced engines in the 2020-2025 timeframe is to reduce GHG
emissions and maintain performance while meeting increasingly stringent criteria pollutant
standards. This challenge is expected to be met through a range of improvements, from the
application of highly-efficient downsized engines through to detailed optimization of components
and systems. This section describes specific technologies or systems that are expected to be
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included in future engines, each of which supports the overall goal of reduced GHG emissions
in future vehicles. Section 4.2, Engine Configurations, describes the complete engine
technology packages that synthesize the effects of the technologies described here to develop
the model inputs used.
4.1.1 Advanced Valvetrains
Several advances in valvetrain technology are expected to be available in the study timeframe.
These technologies are expected to apply to engines across the whole set of vehicle classes
examined in the study.
Advanced valvetrain systems improve fuel consumption and GHG emissions mainly by reducing
pumping losses in the engine. The pumping loss mitigation provides larger benefits at part-load
operation, such as during urban driving. Advanced valvetrains also support engine downsizing,
which provides fuel consumption benefits across the complete engine operating map. Lastly,
they can be used to support faster aftertreatment warm-up through varied timing, leading to
additional, synergistic gains if the faster aftertreatment warm-up creates a benefit to tailpipe-out
NOX emissions that can be traded off to improve GHG emissions.
Two advanced valvetrain options, cam-profile switching and digital valve actuation, were
included in the study and are discussed below. The effects of these valvetrains were integrated
into the model inputs developed for the complete engine technology packages described in
Section 4.2.
4.1.1.1 Cam-Profile Switching Valvetrain
Cam-profile switching (CPS) systems use a hydraulically-actuated mechanical system to select
between two or three cam profiles. CPS systems, such as the Honda VTEC, Mitsubishi MIVEC,
Porsche VarioCam, and Audi Valvelift, have been developed by a number of Japanese and
European manufacturers. Figure 4.1 shows a diagram of Honda's VTEC CPS system (Honda,
2011). CPS systems can be designed to improve low-speed torque or to improve fuel economy
by reducing pumping losses at light load. CPS systems are applicable in all LDV classes. The
benefit to fuel consumption is expected to range up to 7% at specific part-load operating points,
as shown in Figure 4.2, and will therefore provide a larger benefit in city driving than in highway
driving.
4.1.1.2 Digital Valve Actuation Valvetrain
Digital valve actuation (DVA) uses a mechanical, hydraulic, or electrical system to actuate the
valves independently of a camshaft. The full realization of DVA in the study timeframe will be a
camless DVA system, where there is no mechanical linkage between the engine crank and the
valves. The engine fueling maps with DVA were assumed to use camless DVA systems, such
as electrohydraulic or electromagnetic systems. Electropneumatic systems are less mature
currently, but may yet be available late in the timeframe. An example DVA system in current
production is the Fiat MultiAir system, which is an electro-hydraulic system (Fiat, 2009),
although it still uses a camshaft to provide the primary timing for the valve open and valve close
events. The Schaeffler Group's INA UniAir DVA system is shown in Figure 4.3. The DVA system
could be implemented to provide flexibility with valve event timing, valve lift profiles, or both. As
with the CPS systems, the main benefit in GHG emissions is a result of reducing pumping
losses at part-load operation and lower engine speeds, although the benefits at specific
operating points can range up to 12% as shown in Figure 4.4.
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Normal valve
train mechanism
VTEC mechanism
One cam profile
Two different
cam profiles
One
rocker arm
Cross-sectional view Frontal view
Figure 4.1: Honda's VTEC cam profile switching system. (Honda, 2011)
1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000
Engine speed [rev/min]
Figure 4.2: Expected BSFC benefit from CPS system over typical engine operating
map.
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Figure 4.3: INA UniAir digital valve actuation system. (Schaeffler Group, 2010)
a.
HI
5
ffl
Variable valve-lift (DVA) benefit [%]
1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000
Engine speed [rev/min]
Figure 4.4: Expected BSFC benefit from DVA system over typical engine operating
map.
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4.1.2 Direct Injection Fuel Systems
Direct injection (Dl) fuel systems are the standard fuel injection system in use on current diesel
engines. One of the significant changes expected by the 2020-2025 timeframe is a continued
transition from port fuel injection (PFI) to Dl in SI engines as well. For SI engines with Dl, the
fuel is injected directly into the combustion cylinder before being ignited. Dl fuel systems inject
the fuel at a higher pressure than PFI injectors do, and allow the use of multiple injection events
to support advanced combustion control. SI engines with Dl were first introduced in Japan in
1996, and an increasing number of new SI engines now feature Dl.
Using Dl improves fuel consumption across the full range of engine operation, including at part-
load and high-load conditions, with an expected benefit of 2-4%. Dl improves fuel economy by
facilitating a higher compression ratio in the engine, which improves the engine's volumetric and
thermal efficiency. Although detailed injection control strategies were not specifically modeled,
the effects of Dl fuel systems were integrated into the model inputs developed for the complete
engine technology packages described in Section 4.2. The program team used their experience
with research engines and with developing and benchmarking production engines to project that
spray-guided Dl will be the mainstream Dl technology in use in the 2020-2025 timeframe,
supplanting wall guided Dl. Spray-guided Dl offers the capability to deliver a stratified charge—
where the fuel concentration decreases away from the spark plug—that will facilitate lower GHG
emissions through unthrottled lean-burn operation.
For diesel engines, emissions requirements will cause the injection pressures to continue to
increase to the 2000-2400 bar injection pressure range. These very high injection pressures
support better combustion and reduced engine-out emissions. In addition, multiple injection
events will be used to better control the onset and progress of the combustion event in the
cylinder.
4.1.3 Boosting System
Using devices to boost the engine's intake air pressure will increase the torque and power
available from a given engine displacement. By increasing the boost pressure while decreasing
engine displacement, the power level is maintained while reducing pumping work in the engine
by shifting engine operation to higher-load operating points.
The advanced engines in the 2020-2025 timeframe are expected to have advanced boosting
systems to increase the pressure of the intake charge up to 3 bar. Various boosting approaches
are possible, such as superchargers, turbochargers, and electric motor-driven compressors and
turbines. The appropriate technology for 2020-2025 will need to provide cost-effective
improvement in performance and efficiency while mitigating turbo lag. Matching a boosting
system to a particular engine is very important to realize the maximum benefits of this
technology. For this study, the effects of the boosting system are already incorporated in the
engine map to produce a reasonably optimized system performance over a wide range of input
variables.
Turbocharged engines in the 2020-2025 timeframe are expected to have an advanced boost
strategy that provides a smooth acceleration feel. The advanced engines with boost systems
were assumed to have two-stage series sequential turbocharger systems. Turbocharging
means that there is some risk of the vehicle performance being affected by turbo lag, a delay in
the torque rise that results from the dynamics of the gas flow through the engine. This effect is
illustrated in Figure 4.5, which shows the benefits of the two-stage turbo system described by
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Schmuck-Soldan, et al. (2011), that General Motors had tested against twin-scroll
turbochargers. Figure 4.5 shows the torque response using net mean effective pressure
(NMEP), which equals both the difference between the indicated and pumping mean effective
pressures (IMEP and PMEP, respectively), and the sum of the brake and friction mean effective
pressures (BMEP and FMEP, respectively). Turbo lag is most significant during hard
acceleration events, especially when the engine starts at or near its idle speed and load.
Mitigating turbo lag means carefully choosing the capacities of the high pressure and low
pressure compressors and turbines and connecting pipes to provide acceptable steady-state
torque across the engine speed range and an acceptable transient rate of torque rise, often
expressed as the time required to reach 85% of maximum torque at a given engine speed.
Modeling turbo lag effects is described later in Section 6.3, Engine Models.
2,OL TwoStage Turbo Transient Performance, 1500rpm
215Nm/16
Two-Stage Turbo Transient NMEP
TwS Turbo 194KW Transient NMEP
TwS Turbo 233KW Transient NMEP
-3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 13 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6,0 6.5 7.0
Time [sec]
Figure 4.5: General Motors two-stage turbo transient performance.
(Schmuck-Soldan, etaL, 2011)
4.1.4 Other Engine Technologies
Other engine technologies incorporated into the future engines were further improvements in
engine friction leading to a global reduction in engine fuel consumption. This friction reduction is
expected to result from a combination of technology advances, including piston ringpack, bore
finish, lower-viscosity crankcase lubricants, low-friction coatings, valvetrain components, and
bearing technology. The details of these improvements in engine friction were not explicitly
itemized in this study, and were instead treated as a global engine friction reduction.
Another approach is to optimize the overall engine design, for example, by combining engine
components to reduce mass and thermal inertia, giving an improved package and faster warm-
up. Ancillary systems may also be electrified to remove the front engine accessory drive (FEAD)
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and allow variable accessory performance independent of engine speed. (See, for example,
Section 4.5.2, Electric Power Assisted Steering.) The combination of components, such as the
exhaust manifold and cylinder head design, will improve the response time for turbocharging
and aftertreatment warm-up. Electrification of FEAD components, such as the electrical coolant
pump, oil pump, or AC compressor, reduces parasitic losses on the engine and allows
accessory operation to be optimized for the operating point independently of the engine.
4.2 Engine Configurations
Several engine configurations were defined using combinations of the advanced engine
technologies described in Section 4.1 based on an assessment of what would be in mainstream
use in the 2020-2025 timeframe. Five main types of engines were used in the study, and are
described in this section.
The engines considered for the 2020-2025 timeframe were developed using two main methods.
The first method, used with the boosted SI engines, was to review the reported performance of
current research engines, and assume that these current research engines would closely
resemble the production engines of the 2020-2025 timeframe. This method takes current
research engines and refines them to meet production standards, including manufacturability,
cost, and durability. The second method, used with the Atkinson cycle SI and the diesel
engines, was to start from current production engines and then determine a pathway of
technology improvements over the next 10-15 years that would lead to an appropriate engine
configuration for the 2020-2025 timeframe. With both methods, current trends in engine design
and development were extrapolated to obtain an advanced concept performance for the 2020-
2025 timeframe that should be achievable in production volumes. All of the engine fueling maps
developed accounted for the effects of future criteria pollutant standards, assumed to be
equivalent to California ARB's SULEV II or to EPA Tier 2 Bin 2. These fueling maps were
reviewed by EPA and the Advisory Committee to ensure that they were suitable for the study.
The combinations of technologies encompassed in each advanced engine concept provide
benefits to the fueling map, or values of brake-specific fuel consumption (BSFC) over the
operating speed and load ranges of each engine. For these future engines, the BSFC is
improved by up to 10% from current levels. Many of the future engine concepts have low BSFC
values over large zones of the engine operating map, with the best BSFC point often at lower
speeds and part-load conditions. The implementation of these technology packages into the
vehicle performance models is described in Section 6.3.
4.2.1 Stoichiometric Dl Turbo
The basic advanced engine configuration is the Stoichiometric Dl Turbo SI engine. This
advanced engine assumes continued use of a Stoichiometric air-fuel ratio for simplified
aftertreatment using a three-way catalyst. The engine modeled has a peak brake mean effective
pressure (BMEP) of 25-30 bar, which supports significant downsizing compared to current 2010
engines. This high BMEP level is reached through a combination of engine technologies,
including advanced valve actuation, such as CPS; spray-guided Dl; and advanced boost
systems, such as series-sequential turbochargers (see Sections 4.1.1, 4.1.2, and 4.1.3,
respectively). The compression ratio of the engines was set at 10.5:1, which provides a balance
between fuel consumption and performance.
Current research engines of this configuration have been developed by several groups. One
example is the Sabre engine described by Coltman, et a/. (2008) and by Turner, et a/. (2009).
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The Sabre engine uses CPS to reduce pumping losses at part-load operation (Turner, et al.,
2009), but only uses single-stage turbocharging with Dl in a 1.5 t three-cylinder engine to reach
20 bar peak BMEP. Lumsden, et al. (2009) at MAHLE Powertrain have also developed a 1.2 i,
three-cylinder research engine similar to the Stoichiometric Dl Turbo SI engine with a peak
BMEP of 28 bar to support up to 50% downsizing.
The Stoichiometric Dl Turbo engine was assumed to operate with a Stoichiometric air-fuel ratio,
without enrichment, over the complete operating map, even at high-speed, high-load operating
conditions, which significantly improves the fuel consumption in this part of the operating map
as shown in Figure 4.6. This change in operation requires design changes to support the higher
exhaust gas temperatures to ensure protecting the valves, pistons, and exhaust system
components. For example, the future engine configuration uses a cooled exhaust manifold to
keep the turbine inlet temperatures below 950°C over the full operating range of the engine to
mitigate the need for upgraded materials in the exhaust manifold and turbine. This change also
provides benefits to criteria pollutant emissions, especially over the US06 cycle.
100%
90%
g 70%
^ 60%
§ 50%
| 40%
| 30%
z 20%
10%
0%
0 1000 2000 3000 4000 5000
Engine Speed (rpm)
6000
Figure 4.6: Typical region of fuel enrichment in Stoichiometric Dl engines (shown in
blue), eliminated through use of a water-cooled exhaust manifold.
Since the initial conception of the 2020 Stoichiometric Dl Turbo, several companies have
engineered new versions of direct injected turbo engines with fueling maps that closely
resemble the maps that were synthesized and used in this study. One example is the research
engine executed by General Motors described by Schmuck-Soldan, et al. (2011), that uses a
two-stage series sequential boosting system like that envisioned for the Stoichiometric Dl Turbo
engine in a 2.0-t variant of the Ecotec SIDI engine. Presented at the Internationales Wiener
Motorensymposium, General Motors' engine achieves a maximum BMEP of 26.4 bar. The best
BSFC island shown in Figure 4.7 is rather large and the zone of best BSFC (up to 105% of the
minimum BSFC) marked on the map encompasses almost half of the useable engine operating
range. All of the features described by General Motors are similar to those integrated into the
Stoichiometric Dl Turbo engine concept modeled for this program, and consequently the two
engines have very comparable fueling maps.
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2,OL Two-Stage Turbo, Map of BSFC [g/kWh]
re
-Q
0.
Ill
CD
28 ~\
27-
26-
25-
24-
23-
22-
21-
20 -
19-
18-
17-
16 J
15-
14-
13T
12-
I I -
10-
9~
8-
7-
f--
5-
4-
3-
2-
i -
500
1000
1500
2000
2500
3000
3500
4UUO
4500
5000
5500
9000
6500
engine speed [rpm]
Figure 4.7: 2.0-€ General Motors SIDI two-stage boosted engine BSFC map.
(Schmuck-Soldan, et al., 2011)
4.2.2 Lean-Stoichiometric Switching
The Lean-Stoichiometric Dl Turbo SI engine configuration is similar in all respects to the
Stoichiometric Dl Turbo engine described above in Section 4.2.1, except that it uses a fuel-lean
air-fuel ratio with A ~ 1.5 at moderate speeds and loads, such as those seen on the FTP75
cycle. Elsewhere, such as on the US06 cycle, the engine switches to Stoichiometric operation
with a three-way catalyst, to avoid exceeding the expected temperature and space velocity
limits of the lean aftertreatment system. This mixed-mode operation allows the engine to take
advantage of the efficiency benefits of lean operation while mitigating the technical challenges
associated with lean-burn emissions control. Figure 4.8 illustrates the zones of lean and
Stoichiometric operation over the engine operating map.
Fuel lean operation improves fuel consumption by increasing the relative charge volume per unit
of fuel burned, enabling a higher compression ratio, improved charge mixing and less intake
throttling. Nevertheless, while lean operation leads to efficient oxidation of unburned
hydrocarbon and carbon monoxide pollutants in the engine exhaust stream, the presence of
excess oxygen makes reduction of nitrogen oxides (NOX) more challenging. Therefore, an
additional emissions control device, such as a lean NOX trap (LNT) or a urea-based selective
catalytic reduction (SCR) system, would be required to remove NOX from the net oxidizing
exhaust gas. The program team raised concerns about the effectiveness of these NOX removal
systems at the high temperatures and exhaust gas flow rates, or space velocities, easily
reached by SI engines at high engine speed or load, and also about catalyst durability under hot
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and oxidizing conditions over the vehicle life. These concerns suggest that meeting criteria
pollutant levels over a drive cycle such as the US06 could be challenging to the expected end of
life, but advances would be made over the intervening years to make such systems production
feasible.
Therefore, the engine switches to stoichiometric operation when the exhaust temperature
crosses a threshold above which the NOX removal system catalysts would suffer accelerated
degradation. This transition zone between lean and stoichiometric operation is shown in
Figure 4.8. At high load conditions, then, the exhaust emissions are treated using typical three-
way catalysts. The engine therefore performs exactly like the Stoichiometric Dl Turbo engine at
higher load, but has improved BSFC at lower load because it switches to lean operation. A
modest fuel consumption penalty is applied over each drive cycle to account for the use of fuel
or other reducing agent to remove NOX during lean operation.
100% n
90%
1000
2000
3000
4000
5000
6000
7000
Engine Speed (RPM)
Figure 4.8: Zone of lean operation for Lean-Stoichiometric Dl Turbo engine.
4.2.3 EGR Dl Turbo
The EGR Dl Turbo engine is also similar to the Stoichiometric Dl Turbo Engine described in
Section 4.2.1, except that it uses cooled external exhaust gas recirculation (EGR) to reduce
intake throttling and to manage combustion knock and exhaust temperatures. The recirculated
exhaust gas dilutes the air and fuel charge in the cylinder, thereby moderating the temperature
during combustion and allowing operation without enrichment over a higher range of load and
speed. Additionally, the EGR mitigates the tendency for engine knock, potentially enabling a
higher compression ratio, and reduces the need for throttling at low-load operation, thereby
reducing engine pumping losses.
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Dual high-pressure and low-pressure EGR loops were assumed for this engine configuration,
which will require additional components such as EGR valves and a heat exchanger (EGR
cooler) to manage the EGR flow and temperature. EGR rates of up to 20-25% are feasible with
this air system (Cruff, et a/., 2010; Beazley, 2010). EGR use allows a modest overall
improvement in fuel consumption across the complete operating map compared to the
Stoichiometric Dl Turbo engine.
4.2.4 Atkinson Cycle
The Atkinson cycle is characterized by leaving the intake valves open during the start of the
compression stroke, which lowers the effective compression ratio of the engine back to that of
the normal SI engine, but allows for a larger effective expansion ratio. This change in engine
operation improves fuel consumption, but penalizes torque availability at lower engine speeds.
For this reason, Atkinson cycle engines are typically used only in hybrid vehicle applications,
where the electric machine can be used to provide extra torque during launch or other hard
acceleration events.
Separate Atkinson cycle engine fueling maps were developed for the 2020-2025 timeframe with
both CPS and DVA valvetrains. These fueling maps reflect the differing net benefits of the
valvetrains, including actuation losses. These engines are only used with the P2 parallel and
Input Powersplit hybrid powertrains described in Section 4.3, Hybrid Technologies. The torque
curve and fueling map thus generated also reflect the benefits of so-called downspeeding, or a
lower overall operating speed range, which yields further fuel consumption benefits by reducing
frictional losses in the engine (Hohenner, 2010).
4.2.5 Advanced Diesel
The advanced diesel engines for the 2020-2025 timeframe were developed by starting with
existing production engines and identifying technology advances that would lead to further
improvements in fuel consumption. Several of the technologies discussed in Section 4.1,
Advanced Engine Technologies, are applicable to advanced diesels, including series-
sequential, two-stage turbocharging, enhanced EGR and charge air cooling, and CPS. The
composite effects of these technologies were reflected in the improvements made to existing
engine fueling maps to derive the advanced diesel engine fueling maps.
This approach led to different maps being developed for each of the vehicle classes that had
diesel engines available: the Small Car, Full Size Car, Large MPV, LOT, and LHDT. For
example, the LHDT engine torque curve and fueling maps were generated by starting with a
6.61 diesel engine typical for this class and applying the benefits of improvements in pumping
losses or friction to the fueling map. Engine displacements for the advanced diesels were
chosen based on the current torque and power levels available from these engines, the
expected future requirements, and the effects of applying advanced technologies to support
further downsizing. Current diesel engines for LDVs already use advanced variable-geometry
boost systems and high-pressure common-rail direct injection for better torque response and
specific power. Improvements in these areas are therefore expected to be incremental, by
contrast with the more extensive changes to SI engine architectures described above. For
example, the peak BMEP of the advanced diesels is in the 17-23 bar range, which is noticeably
lower than that expected for the advanced SI engines.
This difference is, however, consistent with Ricardo's expectation of the pace and direction of
technology development for diesel engines that comply with the expected emissions
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requirements defined in the study's ground rules defined in Section 3.2, that is, emissions
standards consistent with today's California SULEV II or EPA Tier 2 Bin 2 standards. A modest
fuel consumption penalty was applied to account for the additional fuel required for particulate
filter regeneration and lean NOx aftertreatment.
4.2.6 Fueling Map Development Examples
Examples of each method of developing the advanced engine fueling maps are presented
below. The first example shows how the EGR Dl Turbo engine described in Section 4.2.3 was
developed, and the second, how the Atkinson engine described in Section 4.2.4 was developed.
4.2.6.1 EBDI®to EGR Dl Turbo
The EBDI® engine (Cruff, et a/., 2010; Beazley, 2010) is a recently-developed research engine
that incorporates many of the technologies expected in the EGR Dl Turbo engine and was
therefore the starting point for the advanced engine. Adjustments were then made to the EBDI®
engine fueling map to make it representative of a production engine expected in the 2020-2025
timeframe.
The current research engine has the fueling map shown in Figure 4.9, where the contours show
BSFC (in g/kW-h) as a function of engine speed and BMEP and the best BSFC point marked is
230 g/kW-h at 2000 rpm and 12 bar BMEP. This engine is designed to reach 30 bar BMEP
running on gasoline and up to 35 bar BMEP on E85. To this end, the EBDI® engine uses a 10:1
compression ratio and the single-stage turbocharger is sized to reach 2.88 bar boost pressure.
EGR rates vary from 0% up to 23% during operation. The research engine uses direct injection
and has variable intake and exhaust cam phasing.
3000
2500
re
a.
j*:
:* 2000
•c
0)
0)
(A
Ł1
o
0.
HI
1500
1000
500
450
400
350
300
260
250
245
240
230
220
1000 1500 2000 2500 3000 3500 4000 4500 5000
Engine Speed [rev/min]
Figure 4.9: BSFC map (in g/kW»h) for EBDI® engine with EGR. (Beazley, 2010)
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To translate this to the 2020-2025 timeframe's EGR Dl Turbo engine, the compression ratio
was increased to 10.5:1, which improves the fuel consumption by approximately 1% across the
map. The EGR Dl Turbo engine also assumes use of an advanced boost system as described
in Section 4.1.3 instead of a single-stage system. Switching from the current valvetrain to the
CPS system described in Section 4.1.1.1 will provide up to 7% improvements in the steady-
state fueling map, with the best benefits coming at moderate load and low speed as shown in
Figure 4.2. Lastly, a fuel consumption improvement of 3.5% was applied to account for
continued application of friction reduction technologies. The final fueling map used in the study
for the EGR Dl Turbo engine is the result of synthesizing these technology improvements into a
cohesive whole.
4.2.6.2 Contemporary to Future Atkinson
In the case of the Atkinson cycle engines, the program team started with a contemporary
example of the class of engine and translated it into the future by applying technology
improvements to an existing fueling map. These technology improvements include those
described in Section 4.1.1, Advanced Valvetrains, and Section 4.1.4, Other Engine
Technologies.
Basic Engine Operating Line
Basic operating
1000
2000 3000 4000
Ens ire Speed (rpm)
Figure 4.10: BSFC map (in g/kW»h) for Toyota Prius engine. (Muta, etal., 2004)
An example of a contemporary Atkinson cycle engine is the Toyota Prius engine as presented
by Muta, et a/. (2004), which uses the fueling map shown in Figure 4.10. To translate the current
map to the study timeframe, several adjustments were made to the fueling map. First, the
engine speed range was modified so that the engine would tend to operate at lower speeds,
which reduces frictional losses in the engine. Additional friction reduction improvements, such
as those described in Section 4.1.4, Other Engine Technologies, were also applied to the map.
Furthermore, the Atkinson engines in the design space can use either of the advanced
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valvetrains, the CPS or DVA, which provides additional benefits to fuel consumption at part-load
conditions, especially at lower engine speeds as described in Section 4.1.1 and shown in
Figures 4.2 and 4.4.
These technologies together have the net effect of improving the best BSFC by about 5%, but
more importantly, of substantially improving fuel consumption across the map, especially at
lower-speed and moderate load operating conditions.
4.3 Hybrid Technologies
The selection of hybrid technology for a vehicle is complex, comprising a series of engineering
trade-offs between fuel consumption benefit and system complexity and cost. As the market
share of hybrid vehicles continues to grow, consumers will have a range of choices.
A wide range of hybrid configurations were considered in the initial part of the program, with the
program studying three main approaches: micro hybrid (stop-start), P2 parallel, and Input
Powersplit. For this study, it was assumed that the hybrid powertrain configurations will be
studied in all but the LHDT vehicle class as shown in Table 5.2. The implementation of these
hybrid systems into the vehicle models is described in Section 6.8.
4.3.1 Micro Hybrid: Stop-Start
The most basic hybridization method shuts off the engine during idle periods, and typically uses
an enhanced starter motor and limited use of driver comfort features during engine off, such as
the radio and some heat but not air conditioning. This approach reduces fuel use over city drive
cycles by minimizing idling, but provides no benefit for highway driving or when air conditioning
is requested.
The stop-start, micro hybrid approach is the lowest-cost hybrid system, and can be implemented
relatively quickly on most vehicles on the market today. Stop-start systems are already in
production and the technology is maturing. Further development will lead to increased user
acceptance, for example, through transparent integration with low impact on vehicle
performance or noise, vibration, and harshness (NVH) and by implementing new technologies
to mitigate the effects on cabin cooling (Weissier, 2011).
The program team has assumed that by the 2020-2025 timeframe, all vehicles with an
otherwise conventional powertrain will have stop-start functionality implemented. For the vehicle
models in this study, the starter motor does not provide motive power, but is capable of
recovering enough energy to offset accessory loads.
4.3.2 P2 Parallel Hybrid
The P2 Parallel Hybrid powertrain places an electric machine on the transmission input,
downstream of the engine clutch. This system allows stop-start, electrical launch, launch assist,
and regenerative braking functionality. The clutch also allows the engine to be decoupled from
the rear of the driveline, allowing pure electric propulsion, or electric vehicle (EV) mode
operation. This wide application of electrical power in a variety of vehicle operating conditions
facilitates downsizing the engine from that in the comparable conventional vehicle.
This hybrid powertrain is expected to significantly reduce GHG emissions, especially during city
driving. Highway driving fuel consumption is expected to improve because the electric machine
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in the P2 hybrid allows a smaller, more efficient internal combustion engine to be used. This
smaller engine, however, may limit vehicle performance in situations requiring continuous
engine power, such as a sustained hill climb.
P2 Parallel hybrids are in limited production currently, including such vehicles as the Hyundai
Sonata, the Porsche Cayenne, and the Volkswagen Touareg. Prototypes have also been built
by various companies using existing off-the-shelf components.
A P2 Parallel Hybrid system can be used with an automatic transmission, automated manual
transmission (AMI), continuously variable transmission (CVT), or dual clutch transmission
(DCT). Hellenbroich and Rosenburg (2009) describe a P2 variant with AMI, for example. For
this program, the P2 Parallel Hybrid powertrain was modeled using the DCT, which has fixed
gear ratios and no torque converter, as described in Section 4.4.2.
4.3.3 Input Powersplit
The simplest Powersplit hybrid configuration replaces the vehicle's transmission with a single
planetary gearset and two electrical machines connected to the planetary gearset. The
planetary gearset splits engine power between the mechanical path and the electrical path to
achieve a continuously variable transmission. In some Input Powersplit configurations, a second
planetary gearset is used to speed up one of the electrical machines while retaining the CVT
functionality. The Toyota Prius and the Ford Hybrid Escape are two examples of Input
Powersplit hybrid vehicles currently sold in the US.
With the appropriate electric accessories, the Input Powersplit system allows for EV mode
operation, as well as stop-start operation, electric launch, launch assist, and regenerative
braking. In addition, the system allows for engine downsizing to help reduce fuel consumption,
although the smaller engine may limit vehicle performance in situations requiring continuous
engine power, such as a sustained hill climb. The Powersplit system provides significant
improvements in fuel consumption in city driving. During highway cycles, the benefits of
regenerative braking and engine start-stop are reduced, although the CVT feature of the engine
helps during the highway cycle as the engine is kept at an efficient operating point.
4.4 Transmission Technologies
The U.S. vehicle market is currently dominated by automatic transmissions, with a development
emphasis on increasing the launch-assist device efficiency and on increasing the number of
gear ratios to keep the engine operating in regions of high efficiency. Nevertheless, dual clutch
transmissions (DCT) are expected to be adopted over the next 10 to 15 years because of their
potential to further improve fuel economy and maintain drivability. CVTs tend to have higher
friction than DCTs and provide a different driving experience than stepped transmissions.
Although CVTs are a current production technology, CVTs were not included in the scope of this
study. The baseline 6-speed transmissions used the same gear ratios as the previous fuel
economy study by Ricardo and PQA, (2008) to maintain continuity between improvement
projections. The 6-speed ratios have a total ratio span of 6.05 which is typical of current 6-speed
transmissions that were designed for fuel economy and performance improvements over their 4-
speed or 5-speed predecessors. The 8-speed ratios offer a first gear ratio that has improved
launch torque multiplication over the 6-speed and two overdrive ratios that provide lower engine
rpm than the 6-speed ratios. The gear step progression of the 8-speed transmission is similar to
current production and provides acceptable drivability, and is shown in Table 6.3.
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The development of DCT technology is expected to be implemented in the U.S. based on
experience with European and Japanese applications. Some vehicles with DCTs are entering
volume production, such as the Ford Fiesta, Ford Focus, and VW Passat. Automatic
transmissions too are still being developed and refined, with new technologies being
implemented in luxury vehicles, and then cascaded down to other vehicle classes. Given that
94% of current U.S. transmissions are automatics, efficiency improvements that mitigate GHG
emissions are expected to come from the following:
• Increased gear count from 4-6 currently to 7 or 8 by 2020-2025
• Improved kinematic design
• Component efficiency improvement or alternative technologies
• Launch devices
• Dry sump technology
The various base transmission technologies are described, followed by launch device options,
and, finally, other technologies expected to improve transmission efficiency. The effects of these
various technologies on transmission efficiency were incorporated into the models as described
in Section 6.4, Transmission Models.
4.4.1 Automatic Transmission
The automatic transmission is hydraulically operated, and uses a fluid coupling or torque
converter and a set of gearsets to provide a range of gear ratios. Viscous losses in the torque
converter decrease the efficiency of the automatic transmission. For the study timeframe, it was
assumed that eight-speed automatic transmissions will be in common use, as this supports
more efficient operation. The Small Car is an exception, and was assumed to only have enough
package space to support a six-speed transmission. For the 2020-2025 timeframe, losses in
advanced automatic transmissions are expected to be about 20-33% lower than the losses in
current automatic transmissions from the application of the specific technologies described in
Section 4.4. The overall benefits are compiled from Ricardo's confidential business information
on transmission systems. Additional benefits will be realized by having more gear ratios
available to help maintain the engine near its best operating condition.
4.4.2 Dual Clutch Transmission (DCT)
The DCT has two separate gearsets operating in tandem, one with even gears and the other,
odd. As the gear changes, one clutch engages as the other disengages, thereby reducing
torque interrupt and improving shift quality, making it more like an automatic transmission. The
DCT, however, does not require a torque converter which improves its efficiency compared to
an automatic transmission, and may use either wet or dry type launch clutches. For the study
timeframe, energy losses in both wet clutch and dry clutch DCTs are expected to be 40-50%
lower than in current automatic transmissions. Additional benefits will be realized by having
more gear ratios available to help keep the engine near its best operating condition. As with the
automatic transmission, the Small Car was assumed to only have package space for a six-
speed transmission. An overall comparison of the efficiency of the stepped-gear transmissions
is shown in Figure 4.11.
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5.000
4.500
4.000
3.500
J.OOO
-2020 AT
2,500
Gear Ratio
-2020 DCT
2.000
1.500
1.000
0,500
0.000
2010 Baseline AT
Figure 4.11: Comparison of Automatic and DCT Transmission Efficiencies
4.4.3 Launch Device: Wet Clutch
A wet clutch provides torque transmission during operation by means of friction action between
surfaces wetted by a lubricant. The lubricant is required for cooling during gear shifts when the
clutch is slipping in larger LDV classes. Wet clutch DCTs provide added durability for the higher
torque requirements of larger LDVs, although a secondary lubrication system is needed for the
actuation requirements. As a result, wet clutch systems are expected to be heavier, cost more,
and be less efficient than dry clutch systems. An example of a wet clutch DCT system is shown
in Figure 4.12.
By the 2020-2025 timeframe, wet clutch DCTs are expected to develop into so-called damp
clutch DCTs, which approach the efficiency of a dry clutch with the longevity and higher torque
capacity of a wet clutch. In damp clutch DCTs, a limited spray is applied to cool the clutch
materials. A damp clutch requires a lubrication system but is more efficient due to improved
control, leading to reduced windage and churning losses.
4.4.4 Launch Device: Dry Clutch Advancements
The standard dry clutch requires advanced materials to dissipate heat and prevent slipping. The
thermal load resulting from engagement prevents dry clutches from being used in high torque
and heavy duty cycle applications, even though they are more efficient since they significantly
reduce parasitic shear fluid losses and do not require an additional lubrication system. The GHG
emissions benefit of a dry clutch over a wet clutch should be realized at launch and during
transient driving, thus primarily for city driving. Advancements in materials or electric assist
could enable this technology to be used in larger LDVs and more severe duty cycles by the
study timeframe, but is generally assumed to be prevalent in the smaller vehicle classes.
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Figure 4.12: Typical transverse wet clutch DCT arrangement. (Ricardo and PQA, 2008)
4.4.5 Launch Device: Multi-Damper Torque Converter
Dampers added to the torque converter enable a lower lockup speed, therefore decreasing the
more fuel-intensive period of hydrodynamic power transfer. Multi-damper systems provide
earlier torque converter clutch engagement; however, drivability and limited ratio coverage have
limited the deployment of this technology to date. The technology must be integrated during
transmission design. The GHG emissions benefit should come from reduced slippage and
smoother shifting.
4.4.6 Shifting Clutch Technology
Shift clutch technology improves the thermal capacity of the shifting clutch to reduce plate count
and lower clutch losses during shifting. Reducing the number of plates for the shifting process
and reducing the hydraulic cooling requirements will increase the overall transmission efficiency
for similar drivability characteristics. Technology deployment has been limited by industry
prioritization of drivability over shift efficiency, especially since shift events are a very small
portion of typical driving. The technology will be best suited to smaller vehicle segments
because of reduced drivability expectations—this technology may not be suitable for higher
torque applications.
4.4.7 Improved Kinematic Design
Improved kinematic design uses analysis to improve the design for efficiency by selecting the
kinematic relationships that optimize the part operational speeds and torques. Large
improvements in efficiency have been noted for clean sheet designs for six-speed and eight-
speed transmissions. This approach will provide a GHG emissions benefit across all vehicle
classes and operating conditions.
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4.4.8 Dry Sump
A dry sump lubrication system provides benefits by keeping the rotating members out of oil,
which reduces losses due to windage and churning. This approach will provide a GHG
emissions benefit across all vehicle classes, with the best benefits at higher speeds.
4.4.9 Efficient Components
Continuous improvement in seals, bearings and clutches aimed at reducing drag in the system
should provide GHG emissions benefits without compromising transmission performance.
4.4.10 Super Finishing
This technology approach chemically treats internal gearbox parts for improved surface finish.
The improved surface finish reduces drag which increases efficiency over the full range of
operation.
4.4.11 Lubrication
New developments in base oils and additive packages will reduce oil viscosity while maintaining
temperature requirements, thereby improving transmission efficiency over the full range of
operation.
4.5 Vehicle Technologies
Several vehicle technologies were also considered for the study to the extent that they help
support future ranges of vehicle mass, aerodynamic drag, and rolling resistance for each of the
vehicle classes in the study. The potential levels of improvement for these "road load reduction"
technologies were not explicitly quantified; rather, they were included as independent input
variables within the complex systems modeling approach.
Technologies considered include mass reduction through use of advanced materials with a
higher strength to mass ratio and through consolidation and optimization of components and
systems. Aerodynamic drag is expected to see improvements through adoption of both passive
and active aerodynamic features on vehicles in the 2020-2025 timeframe. Continued
improvement in tire design is expected to reduce rolling resistance and thereby provide a benefit
to fuel consumption.
In addition, vehicle accessory systems such as the cooling pumps and power steering systems
are expected to become electrified by the 2020-2025 timeframe. These electrified accessories
should reduce the power required to keep them active, which will also improve fuel
consumption, and are described in greater detail below.
4.5.1 Intelligent Cooling Systems
Intelligent cooling systems use an electric coolant pump to circulate engine coolant, removing
the power required for this pump from the FEAD. Removing the coolant pump from the FEAD
also enables independent pump speed control. Rather than running at a fixed multiple of the
engine speed, the coolant pump can spin at the appropriate speed for the current cooling
requirements. Standard cooling systems are sized to provide cooling at maximum load and
ambient conditions, but most vehicles only rarely operate under these extreme conditions.
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Intelligent cooling also enables quicker warm-up of the engine by controlling coolant flow. This
reduces engine friction by increasing engine temperature during the warm up process. The
effects of the cooling system performance were integrated into the vehicle performance model.
Ricardo estimates this technology will lower fuel consumption over the FTP cycle. BMW is
implementing this technology on their twin-turbo 3-L inline-6 cylinder engine, introduced in 2007
in their 335i model. This technology is projected to be readily available by the 2020-2025
timeframe.
4.5.2 Electric Power Assisted Steering
Electric Power Assisted Steering (EPAS) uses either rack or column-drive electric motors to
assist driver effort instead of a hydraulic power assist system. EPAS replaces the engine-driven
hydraulic pump, hydraulic hoses, fluid reservoir, fluid, and hydraulic rack. The efficiency of this
system is a result of reduced FEAD losses and improved energy management that comes from
decoupling the load from the engine. This technology is currently available for small and
medium sized passenger vehicles, and it is likely that this will be commercially available for
LDVs up to the LOT class by the 2020-2025 timeframe. This technology is required for vehicles
with any electrical launch or EV mobility, so that the vehicle can be steered during EV mode.
5. TECHNOLOGY BUNDLES AND SIMULATION MATRICES
The program team and EPA, with input from the Advisory Committee, bundled the technologies
described in Chapter 4, Technology Review, into a set of technology packages to be evaluated
in the seven LDV classes described in Section 2.2, Ground Rules for Study. These LDV classes
are Small Car, Standard Car, Small MPV, Full Size Car, Large MPV, LOT, and LHDT.
Engineering judgment was used to select technology combinations deemed most appropriate
for each vehicle class. For example, the larger LDV classes were assumed to have wet clutch
DCTs to accommodate the higher torques from their engines.
5.1 Technology Options Considered
Definitions of the hybrid powertrain, engine, and transmission technology packages are
presented in Tables 5.1-5.3. The engine technologies are defined in Table 5.1; hybrids, in Table
5.2; and transmissions, in Table 5.3. Many of the engines in Table 5.1 use some measure of
internal EGR, but for this table "Yes" means significant EGR flow through an external EGR
system. All of the advanced transmissions in Table 5.3 include the effects of the transmission
technologies described in Section 4.4, including dry sump, improved component efficiency,
improved kinematic design, super finish, and advanced driveline lubricants.
5.2 Vehicle configurations and technology combinations
Vehicles were assessed using three basic powertrain configurations: conventional stop-start, P2
hybrid, and Input Powersplit hybrid. Each vehicle class considered in the study was modeled
with a set of technology options, as shown in Table 5.4 for the baseline and conventional
powertrains and Table 5.5 for the hybrid powertrains. Each of the 2020 engines marked for a
given vehicle class in Table 5.4 was paired with each of the advanced transmissions marked for
the same vehicle class. Tables 5.4 and 5.5 also show the ranges of the continuous
parameters—expressed as a percentage of the nominal value—used in the DoE study for the
conventional and hybrid powertrains, respectively. The ranges were kept purposely broad, to
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cover the entire span of practical powertrain design options, with some added margin to allow a
full analysis of parametric trends.
Table 5.1: Engine technology package definition.
Engine
2010 Baseline
Stoich Dl Turbo
Lean-Stoich Dl Turbo
EGR Dl Turbo
Atkinson
Diesel
Air
System
NA
Boost
Boost
Boost
NA
Boost
Fuel
Injection
PFI
Dl
Dl
Dl
Dl
Dl
EGR
No
No
No
Yes
No
Yes
Valvetrain
CPS DVA
No
Yes
Yes
Yes
Yes
Yes
No
No
No
No
Yes
No
Table 5.2: Hybrid technology package definition.
Function
Engine idle-off
Launch assist
Regeneration
EV mode
CVT (Electronic)
Power steering
Engine coolant pump
Air conditioning
Brake
2010 Baseline
No
No
No
No
No
Belt
Belt
Belt
Standard
Powertrain Configuration
Stop-Start P2 Parallel
Yes Yes
No Yes
No Yes
No Yes
No No
Electrical Electrical
Belt Electrical
Belt Electrical
Standard Blended
Powersplit
Yes
Yes
Yes
Yes
Yes
Electrical
Electrical
Electrical
Blended
Table 5.3: Transmission technology package definition.
Transmission
Baseline Automatic
Advanced Automatic
Dry clutch DCT
Wet clutch DCT
Launch Device
Torque Converter
Multidamper Control
None
None
Clutch
Hydraulic
Hydraulic
Advanced Dry
Advanced Damp
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Table 5.4: Baseline and Conventional Stop-Start vehicle simulation matrix.
Vehicle Class
Small Car
Standard Car
Small MPV
Full Size Car
Large MPV
LOT
LHDT
08
a) <2
C 0> H
L1J <Ł 0
Q) /A *j*
•-
W Q
•Ł si
•g *-
< 5
X
X
X
X
X
X
Parameter
Engine Displacement
Final Drive Ratio
Rolling Resistance
Aerodynamic Drag
Mass
Electric Machine Size
DoE Ra
P2 Hybrid
50 150
75 125
70 100
70 100
60 120
50 300
nge (%)
Powersplit
50 125
75 125
70 100
70 100
60 120
50 150
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6. VEHICLE MODEL
Vehicle models were developed to explore the complete design space defined by the
technologies, vehicle classes, and powertrain architectures included for the 2020-2025
timeframe. The modeling process started by developing baseline models to compare against
data for current (2010) vehicles, as described in Section 6.1, Baseline Conventional Vehicle
Models, and Section 6.2, Baseline Hybrid Vehicle Models. Specific subsystems were also
implemented into the simulation package for the study, and these modeling activities are
described in Sections 6.3-6.8.
6.1 Baseline Conventional Vehicle Models
For each of the seven LDV classes considered in this project, vehicle models were developed
and correlated to a corresponding 2010 exemplar for each LDV class for the purposes of
establishing a comparison against known vehicle data. A detailed comparison between baseline
model results and vehicle test data were used to validate the models. These correlation models
were then modified to form the 2010 baseline models by converting all of them to use a 2010-
level six-speed automatic transmission and stop-start systems. These baseline models, while
representing an advance from current production vehicles, provide a better basis for comparison
with the advanced LDVs for the 2020-2025 timeframe.
The starting point for the vehicle models was to use the existing road-load coefficients from the
EPA Test Car List, which are represented as the target terms for the chassis dynamometer.
Known as target A-B-C terms, the coefficients were used to derive the physical properties of
rolling resistance, linear losses, and aerodynamic drag. These properties were then used in the
simulation to provide the appropriate load on the vehicle at any given speed.
A physics-based vehicle and powertrain system model such as the one shown in Figure 6.1 was
developed and implemented in MSC.EasyS™. MSC.EasyS™ is a commercially available
software package widely used in industry for vehicle system analysis, which models the physics
in the vehicle powertrain during a drive cycle. Examples of vehicle performance simulation using
MSC.EasyS™ include work by Anderson, et a/. (2005) and Fulem, et a/. (2006), as well as the
previous EPA study for 2012-2016 LDV configurations (Ricardo and PQA, 2008). Torque
reactions are simulated from the engine through the transmission and driveline to the wheels.
The model reacts to simulated driver inputs to the accelerator or brake pedals, thus enabling the
actual vehicle acceleration to be determined based on a realistic control strategy. The model is
divided into a number of subsystem models. Within each subsystem the model determines key
component outputs such as torque, speeds, and heat rejection, and from these outputs,
appropriate subsystem efficiencies can be calculated or reviewed as part of a quality audit.
The seven vehicle classes considered in this study are shown in Table 6.1, along with the
baseline vehicles for each class. Each of the baseline exemplar vehicle models had vehicle-
specific vehicle, engine, and transmission model parameters. The models were exercised over
the FTP75 and HWFET fuel economy drive cycles, and the results compared with the EPA
Vehicle Certification Database (Test Car List) fuel economy data for each of the baseline
exemplar vehicles.
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Engine
Accessories
DJrjvetnjin
Figure 6.1: MSC.EasyS conventional vehicle model.
Table 6.1: Vehicle classes and baseline exemplar vehicles.
Vehicle Class
Baseline Exemplar
Small car
Standard car
Small MPV
Full sized car
Large MPV
LOT
LHDT
Toyota Yaris
Toyota Camry
Saturn Vue
Chrysler 300
Dodge Grand Caravan
Ford F150
Chevy Silverado 3500HD
6.2 Baseline Hybrid Vehicle Models
For each hybrid technology, Ricardo developed a baseline model to calibrate the hybrid control
strategy and vehicle, engine, and driveline parameters. As with the conventional vehicles
described in Section 6.1, a full physical model of each baseline hybrid vehicle was developed
and implemented in MSC.EasyS™. The hybrid control algorithms are also implemented in the
respective MSC.EasyS™ models. The vehicles were modeled using published information from
various sources and Ricardo proprietary data.
6.3 Engine Models
The engines considered in the design space are defined by their torque curve, fueling map, and
other input parameters. For the 2010 baseline vehicles, the engine fueling maps and related
parameters were developed for each specific baseline exemplar vehicle. For the engines used
in the 2020-2025 vehicles, reference engine models were developed, which were then scaled
to each of the LDV classes.
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As described in Section 4.2, Engine Configurations, and illustrated in Section 4.2.6, Fueling Map
Development Examples, the program team used two methods to develop the engine models for
the 2020-2025 timeframe. The first was to look at the reported performance of current research
engines, and translate these to the production engines of the 2020-2025 timeframe. With this
method, current research engines would be refined to meet production standards, including
manufacturability, cost, and durability. The second method was to start from current production
engines and then determine a pathway of technology improvements over the next 10-15 years
that would lead to an appropriate engine configuration for the 2020-2025 timeframe.
The fueling maps and other engine model parameters used in the study were based on
published data and Ricardo proprietary data. These initial maps were then developed into a
map reflecting the effects on overall engine performance of the combination of the future
technologies considered. Specifically, the effects of the valve actuation system, fueling system,
anti-knock calibration, and boost system were integrated into the final torque curves and fueling
maps, therefore subsystem performance maps, such as turbine and compressor efficiency
maps, are not relevant to this study.
Each proposed map was then reviewed and approved by EPA and the Advisory Committee.
This process was repeated for each of the engine technologies included in the simulation
matrix, as shown in Tables 5.4 and 5.5 for conventional stop-start and hybrid powertrain
configurations, respectively.
Engine downsizing effects were captured using a standard engineering method, by changing
the engine displacement in the given vehicle. This approach assumes that the downsized
engines have the same brake mean effective pressure (BMEP), which scales the engine's
delivered torque by the engine swept volume, or displacement. The BSFC of the scaled engine
map is also adjusted by a factor that accounts for the change in heat loss that comes with
decreasing the cylinder volume, and thereby increasing the surface to volume ratio of the
cylinder. These adjustment factors are plotted in Figure 6.2, and are drawn from Ricardo
proprietary data on the effect of displacement on BSFC. The minimum number of cylinders in an
engine was set to three, and the minimum per-cylinder volume, to 0.225 liters. These
constraints then set the minimum engine displacement in the design space to 0.675 liters.
Engine efficiency is therefore function of engine speed and BMEP, with specific fueling rates
(mass per unit time) calculated from the torque. Thus, downsizing the engine directly scales the
delivered torque, and the fueling map is adjusted accordingly. The engine speed range was held
constant over the engine displacement ranges of interest.
Turbo lag was represented in the model by applying a first order transfer function between the
driver power command and the supplied engine power at a given speed. This transfer function
was only used during the performance cycle, which is a hard acceleration from a full stop used
to assess vehicle acceleration performance. The transfer function approximates the torque rise
rate expected in the engines with turbocharger systems during vehicle launch. Adjusting the
time constant in the transfer function allowed the acceleration performance to see the effect of
turbo lag. A time constant of 1.5 seconds was selected to represent the expected delay in
torque rise on the advanced, boosted engines from the spool up of the turbine. Referring back
to the General Motors 2.0-t SIDI engine, turbo transient performance is also characterized by
Schmuck-Soldan, et al. (2011), as shown in Figure 4.5. The transient response depicted here
is in line with the representation used in this study. EPA also reviewed its own engine
development data and corroborated the 1.5 second time constant.
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•SI Engine
•Cl Engine
250 300
350
400 450 500 550 600 650
Volume per cylinder
Figure 6.2: Change in BSFC resulting from cylinder heat loss.
6.3.1 Warm-up Methodology
A consistent warm-up modeling methodology was developed for the study to account for the
benefits of an electrical water pump and of warm restart for the advanced vehicles. To account
for engine warm-up effects, Ricardo used company proprietary data to develop an engine warm-
up profile. This engine warm-up profile is used to increase the fueling requirements during the
cold start portion of the FTP75 drive cycle. This correction factor for increased fueling
requirements is applied to the fuel flow calculated during the warm-up period in the FTP75 drive
cycle. Section 6.7 provides additional details on how this correction factor was modeled.
6.3.2 Accessories Models
Parasitic loads from the alternator were assumed constant over the drive cycles and were
included in the engine model. Alternator efficiency was assumed to be 55% for baseline vehicle
simulations. Ricardo suggested a 70% efficient alternator in all of the advanced technology
package simulations to represent future alternator design improvements. EPA agreed that this
assumption was consistent with confidential industry projections.
Power-assisted steering (PAS) systems—full electric or electric hydraulic—were modeled as
being independent of engine speed and were included in the engine model for each baseline
vehicle. The EPAS systems assumed no engine parasitic loads on the EPA drive cycles and
acceleration performance cycles, which require no steering input. All advanced package
simulations included the benefit of EPAS. The LHDT and LOT classes used electric hydraulic
PAS, whereas the five smaller vehicle classes used full electric PAS.
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The LOT and LHDT models also include engine parasitic losses due to a belt-driven engine
cooling fan. The other vehicles were assumed to have electric radiator fans, with the load being
drive cycle dependent and added to the vehicle's base electrical load. These accessory loads
are shown in Tables 6.3 and 6.4.
Table 6.3: Accessory loads for conventional stop-start and P2 hybrids.
Vehicle Class
Small car
Standard car
Small MPV
Full sized car
Large MPV
LOT
LHDT
Conventional Accessories (W)
FTP HWFET
Base cooling fan cooling fan
153
153
153
153
153
153
153
127
127
127
127
127
*
**
280
280
280
280
280
*
**
P2 Hybrid Accessories (W)
FTP HWFET
Base cooling fan cooling fan
84
84
84
84
84
84
70
70
70
70
70
*
154
154
154
154
154
*
— — —
Table 6.4: Mechanical cooling fan loads for LOT and LHDT.
Engine
Speed (rpm)
500
1000
2000
2500
6200
Cooling Fan (W)
*LDT **LHDT
242 290
500 600
1058 1270
1323 1588
3550 4260
Current production cars have begun incorporating advanced alternator control to capture
braking energy through electrical power generation. This is done by running the alternator near
or at full capacity to apply more load on the engine when the driver demands vehicle
deceleration. It is believed that this feature will be widespread in the near future and, hence, the
study captures it by incorporating this function into the Conventional Stop-Start model. As in the
earlier study (Ricardo and PQA, 2008), the alternator efficiency was increased to 70% to reflect
an improved efficiency design for 2020 vehicle configurations. The advanced alternator control
strategy monitors vehicle brake events and captures braking energy when available. The control
strategy also limits the maximum power capture to 2800 Watts based on the assumption that
the advanced alternator is limited to 200 Amps at 14 Volts charging for a standard (12V)
advanced glass-mat battery. By integrating power, energy is accumulated from every brake
event and when there is available "stored" brake energy, the control strategy switches the
parasitic draw from the engine to the battery until the accrued energy is consumed, at which
point the load switches back to the engine. For the five smaller LDV classes, both the fan and
base electrical loads are included in the advanced charging system as electric fans are
employed. The system will only benefit the two truck classes, LOT and LHDT, in terms of base
electrical load as these vehicle classes use mechanical fans.
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6.4 Transmission Models
The transmission models use a simplified efficiency curve, where the gearbox efficiency is a
function of gear ratio, as shown in Figure 4.11. Efficiencies for each gear ratio were calculated
based on data from several transmission and final drive gear tests, were averaged over the
expected speed and load ranges for the transmission in a given gear, and incorporate hydraulic
pumping losses. Transmission efficiencies were calculated to represent the average of the
leading edge for today's industry and not one particular manufacturer's design.
Different efficiency curves were mapped for planetary, automatics, and dual-clutch, with the
DCT efficiency modified depending on whether a dry or wet clutch is used. Advanced automatic
transmission designs are projected to reduce losses by 20-33% from current automatic
transmissions. In addition, the advanced automatic transmissions use advanced torque
converters, described below in Section 6.5. Wet clutch DCT efficiencies are also projected to
approach current dry clutch DCT efficiencies.
The gear ratios chosen for the six and eight speed advanced transmission are taken from
current production values for gear ratios. These are shown below in Table 6.5. Moreover,
transmission inertias were adapted from Ricardo proprietary data on contemporary
transmissions and reflect the effects of the technologies described in Sections 4.4.6-4.4.11.
Table 6.5: Transmission gear ratios for six-speed and eight-speed transmissions.
Gear
1
2
3
4
5
6
7
8
Ratio
8 Spd Advanced
4.700
3.130
2.100
1.670
1.290
1.000
0.840
0.670
6 Spd Baseline
4.148
2.370
1.556
1.155
0.859
0.686
In anticipation of future technology packages, it is expected that some advanced level of
transmission shift optimization will be implemented in year 2020-2025 vehicles. For the 2020-
2025 Conventional Stop-Start architecture, an advanced transmission controller was
implemented to determine the most favorable gear for a given driver input and vehicle road
load. This approach takes the place of predefined calibration shift maps based on throttle and
vehicle speed.
The advanced transmission shift optimization strategy tries to keep the engine operating near its
most efficient point for a given power demand. In this way, the new shift controller emulates a
traditional CVT by selecting the best gear ratio for fuel economy at a given required vehicle
power level. In conjunction, gear efficiency of the desired gear is also taken into account. More
often than not, the optimal gear ratio will be in between two of the fixed ratios, and the shift
optimizer will then decide when to shift up or down based on a tunable shift setting. This will
enable the shift optimizer to make proper shift decisions based on the type of vehicle and the
desired aggressiveness of the shift pattern. To protect against operating conditions out of
normal range, several key parameters were identified, such as maximum engine speed,
minimum lugging speed, and minimum delay between shifts. For automatic transmissions, the
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torque converter is also controlled by the shift optimizer, with full lockup only achievable when
the transmission is not in first gear. Shift time for all transmissions was kept constant at 0.7
second duration as the sensitivity of this parameter was not enough to alter fuel economy
predictions over the EPA drive cycles. Furthermore, torque interrupt during shift is handled
automatically by the MSC.EasyS™ model component. During development of this strategy, it
was noted that fuel economy benefits of up to 5% can be obtained when compared to traditional
shift maps. Figure 6.4 compares the desired gear ratio from a CVT and the comparable DCT
fixed gear ratio selected by the shift optimizer strategy.
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
II
200
400
CVT
600 800
Time [s]
1000
1200
1400
DCT (shift optimizer)
Figure 6.4: Comparison of CVT and optimized DCT gear ratios over drive cycle.
Analysis of the optimized shift strategy model output data shows no evidence to suggest an
increase in shift busyness compared to a baseline transmission shift strategy for a given
gearset. Figure 6.5 shows transmission gear plotted over time for a section of the FTP drive
cycle for the 2020 Small Car with 6-speed automatic transmission (and stoichiometric Dl turbo
engine) nominal run with optimized shifting, compared to the 2010 Small Car baseline. For the
complete FTP cycle, the baseline vehicle shifted a total of 238 times, whereas the 2020 vehicle
with optimized shifting strategy shifted 228 times—in this case, leading to a decrease in shift
busyness.
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Computer Simulation of LDV Technologies for GHG Emission Reduction in the 2020-2025 Timeframe
60
50
40
•n
QJ
S 30
20
10
0
re
oj
13
—Veh speed
—6-spd baseline
—6-spd optimized
0 100 200 300
Test time [s)
400
500
Figure 6.5: Comparison of shift activity for traditional and optimized shifting
strategies.
6.5 Torque Converter Models
Torque converter characteristics curves for torque ratio and K-factor were generated using
typical industry standards for efficiency. Each vehicle's torque converter characteristics for
torque ratio and K-factor were tailored for the application based on Ricardo experience with
production systems. Impeller and turbine rotational inertias are also input to the model and were
estimated based upon Ricardo experience and benchmarking data. Vehicle simulations with
advanced automatic transmissions include a slight improvement in torque converter efficiency.
A lockup clutch model was used with all torque converters and was of sufficient capacity to
prevent clutch slip during all simulation conditions. For the baseline models with six-speed
automatics, lockup was allowed in fourth, fifth, and sixth gears. During light throttle conditions a
minimum engine operating speed of 1400 rpm for 13 engines, 1300 rpm for 14 engines,
1200 rpm for V6 engines, and 1100 rpm for V8 engines with the converter clutch locked was
considered in developing the baseline lock/unlock maps. The advanced automatic transmission
applications allow torque converter lockup in any gear except first gear, up to sixth for the Small
Car or eighth for the other LDV classes. This aggressive lockup strategy minimizes losses in the
torque converter.
6.6 Final Drive Differential Model
Baseline final drive ratios were taken from published information and driveline efficiencies and
spin losses were estimated based upon Ricardo experience for typical industry differentials. The
spin losses of the 4-wheel-drive LOT and LHDT front axle and transfer case were included in
the model to capture the fuel economy and performance of the 4-wheel-drive powertrain
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operating in 2-wheel-drive mode. This approach is similar to the EPA procedure for emissions
and fuel economy certification testing.
6.7 Driver Model
The vehicle model is forward facing and has a model for the driver. The driver model applies the
throttle or brake pedal as needed to meet the required speed defined by the vehicle drive cycle
within the allowed legislative error. This allows the modeling of the actual vehicle response to
meet the target drive cycle.
The driver model contains the drive cycle time/velocity trace, controls the throttle and brake
functions, and maintains vehicle speed to the desired set point. Vehicle simulations for fuel
economy were conducted over the EPA FTP75 (city), HWFET (highway) and US06 drive cycles.
The FTP75 cycle consists of three "bags" for a total of 11.041 miles on the conventional
vehicles and an additional bag 4 on hybrid vehicles for a total of 14.9 miles. A ten minute
engine-off soak is performed between bags 2 and 3 (after 1372 seconds of testing). A bag 1
correction factor is applied to the simulated "hot" fuel economy result of the vehicles to
approximate warm-up conditions of increased engine and driveline friction and sub-optimal
combustion. The correction factor reduces the fuel economy results of the FTP75 bag 1 portion
of the drive cycle by 20% on the current baseline vehicles and 10% on 2020-2025 vehicles that
take advantage of fast warm-up technologies.
6.8 Hybrid Models
The hybrid models include all of the conventional vehicle components with the addition or
replacement of components for electric motor-generators, high voltage battery, high voltage
battery controller/bus, transmission, regenerative braking and hybrid supervisory controller. Of
these, the critical systems for the model were the electric machines (motor-generators), power
electronics, and high-voltage battery system. For each of these systems, current, state of the art
technologies such as those described in Staunton, et al. (2006) or Burress, et al. (2008) were
adapted to an advanced, 2020-2025 version of the system.
Technology improvements applied included decreasing losses in the electric machine and
power electronics to represent continued improvements in technology and implementation, so
that a contemporary motor-inverter efficiency map such as that shown in Figure 6.6 would end
up with higher peak efficiency and a broader island of good efficiency. There are several
potential sources of losses in both the inverter and the motor, and the program team assumed
each source would be improved somewhat, leading to an overall 10% reduction in losses in the
inverter and an overall 25% reduction in losses in the motor.
As for the battery pack, a ground rule of the study is that the battery pack would use a generic
lithium ion chemistry representative of what is expected to be in production by the 2020-2025
timeframe. The assumptions for this future class of batteries include a lower overall internal
resistance. Likewise, future hybrid vehicles are assumed to use 40% of the overall SOC range
of the pack, which will reduce the overall battery pack size for a given energy storage
requirement. The capacity of the battery packs in the model was assumed to be sufficiently
large that it did not limit the vehicle performance. The electric machines were swept over a
sufficiently large range such that the design space included configurations where 90% of the
mechanical braking energy on the US06 to be captured by the hybrid electrical system. The
electrical system architecture assumes a DC/DC converter between the battery pack and the
inverter, so the specific pack architecture and voltage are not relevant to the simulation.
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300
250
200
150
100
50
n
92
90
88
86
84
82
80
78
500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000
Speed (RPM)
Figure 6.6: 2007 Camry motor-inverter efficiency contour map. (Burress, et a/., 2008)
fidelay time)
Red: Braking Mode
Black: Accel Mode
flthrottle.veh spd)
Figure 6.7: High level state flow diagram for the hybrid control strategy.
In addition, a Ricardo proprietary methodology was used to identify the optimum boundaries of
fuel consumption for a given hybrid powertrain configuration over the drive cycles of interest:
FTP, HWFET, and US06. The methodology used the drive cycle profile to identify the features
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and thresholds of a control strategy that could provide fuel consumption over the drive cycle that
approaches the boundary value. The result of this assessment enabled the development of a
robust energy management system to control power flow. The simulation results using the
hybrid controller were then compared against the offline strategy to ensure that the hybrid
controller in the models is obtaining the most out of the hybrid powertrain. Furthermore, the
control strategy was designed to allow for a wide range of input parameters while striving for the
most efficient operation modes. Figure 6.7 illustrates the state flow diagram for the hybrid
control strategy used as the baseline for the hybrid control algorithm implemented in
MSC.EasyS™, as well as the state variables, driver inputs and system parameters that were
used to define the state transitions. There are six main operation state modes,
• Idle engine off mode: This mode will shut the engine off and set the throttle command to
zero.
• Electric vehicle mode: This mode will leave the engine off and use the throttle command
from the driver to determine the torque command for the electrical machine.
• Engine-Vehicle synch mode: This mode will start the engine.
• Normal driving model: This mode determines the ratio of electrical machine and engine
power that will be transmitted to the wheel to achieve the desired demand.
• Idle mode: This mode starts the countdown for idle engine off mode.
• Regen mode: This mode determines if regenerative braking is possible and how much of the
requested brake torque will be assigned to foundation brakes and to the electrical machine.
The following inputs and variables or states should be defined and available within the controller
in order to full define the state transitions,
• Driver inputs: throttle and brake pedals
• Battery State of Charge (SOC)
• Vehicle speed
• Engine: power and speed
• Motor: max power, max torque, speed, and torque/power.
Because the design space encompasses a large range of engine displacement and motor sizes,
the input parameters were normalized to take into account these changes and automatically
adjust the controller thresholds to meet the new demands. Figure 6.8 depicts the engine
demand curve that targets high efficiency operation.
A key feature of the hybrid controller is that it used a hybrid load following and load averaging
strategy to help keep the engine on or near its line of best efficiency on the engine operating
map with some accommodation for the efficiency of the overall powertrain. If the engine is
required to be on during low-load conditions, the engine can be made to work harder and more
efficiently and store the excess energy in the battery. While there have been concerns about the
effectiveness of a load averaging strategy given the roundtrip efficiency of energy storage and
retrieval, with the improvements expected in the 2020-2025 timeframe, the engine is likely to be
a critical factor in the balance of efficiency improvements. In the simulation environment, two
identical vehicles were analyzed, one with load averaging active and the other, not. The case
with load averaging showed a slight improvement in fuel consumption over the EPA drive
cycles. In other cases, the energy in the battery can be used to provide launch assist or EV
mode driving. All hybrid vehicle simulations were repeated over the drive cycles until the change
in SOC from start to finish was within 1% of total capacity. Therefore, there is no net
accumulation or net depletion of energy in the battery, and the fuel consumption value reported
is an accurate measure of the effectiveness of technologies. Figure 6.9 shows the energy
supervisory strategy of the hybrid powertrains.
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Rr>st RsFC Ikc/lW.h] Curve 'm thp power rmp Ł IKT>. map)
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Energy Supervisory Strategy
Driver Demand Pedal
Power
Engine Power Demand
Distribution
Battery Power Demand (Driving)
Battery SOC
Battery State
of Charge
(SOC) Control
Driver Brake Pedal
Brake
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Computer Simulation of LDV Technologies for GHG Emission Reduction in the 2020-2025 Timeframe
7. MODEL VALIDATION RESULTS
Before executing the DoE simulation matrix, the vehicle models described in Chapter 6 were
validated. Baseline exemplar vehicles were modeled, and the simulation results compared
against publicly available data on vehicle performance, including acceleration times and fuel
economy. Details of the model validation process and results are presented below. In addition,
nominal runs were prepared for each major powertrain type to provide a reference point for the
input parameters against which to compare the full design space explored in the DoE simulation
matrix.
7.1 Validation Cases and 2010 Baseline Vehicle Models
Vehicle models were developed for a 2010 validation case for each of the seven LDV classes.
Each LDV class was assigned a representative exemplar vehicle for the purposes of
establishing a baseline against known vehicle data. Ricardo leveraged the peer-reviewed
validation baseline models from its 2008 study with PQA (now SRA) for the five LDV classes
from Standard Car through LOT to provide the validation case models, and to build new
validation case models for the Small Car and LHDT classes. The validation case models are
based on the corresponding exemplar vehicles listed in Table 6.1, and therefore use automatic
transmissions and engines with comparable characteristics, including number of gears, peak
torque, and displacement.
Vehicle performance simulation results for the validation case models are shown below in
Table 7.1, comparing the raw fuel economy results in the EPA Test Car List (EPA, 2010)
against the calculated results. In addition to the fuel economy tests, the launch performance
was also assessed for each of the exemplar vehicles, with particular attention paid to the 0-60
mph acceleration time, as this is readily available for validation. 0-60 mph acceleration times for
the exemplar models were within a few tenths of a second of published times for each vehicle.
Because production P2 hybrids were not available to provide data in 2010, no direct comparison
was made. Furthermore, any production hybrid vehicle will be optimized for a specific
combination of engine, electric machine, and battery, whereas this study used a generic but
effective controller that allowed the entire design space to be robustly simulated.
Table 7.1: Validation vehicle fuel economy performance.
Vehicle Class Baseline Exemplars
Small car 2010 Toyota Yaris
Standard car 2007 Toyota Camry
Small MPV 2008 Saturn Vue
Full sized car 2007Chrysler 300
Large MPV 2007 Dodge Grand Caravan
LOT 2007 Ford F1 50
LHDT 2010 Chevy Silverado
3500HD (diesel)
EPA Test List (mpg)
FTP75 HWFET
37 48
27 42
24 37
21 34
20 32
16 23
— —
Simulation Results (mpg)
FTP75 HWFET
37 48
27 42
25 36
22 33
20 29
15 23
13 21
Difference (%)
FTP75 HWFET
-0.8% 0.2%
0.9% -1.0%
3.9% -2.6%
3.7% -4.6%
1.6% -9.1%
-4.1% -0.4%
— —
Following the model validation phase, 2010 baseline vehicles were established. Rather than
using the validation vehicles and corresponding fuel economy results, a new set of baseline
values were determined to facilitate a uniform comparison between the advanced (future)
concepts and today's current technologies. These new reference 2010 baseline vehicles add an
efficient alternator and stop-start operation to a common 6-speed automatic transmission, and
retain the engine maps from the validation case models. Appendix 3 presents the 2010 baseline
model fuel economy and CO2 output equivalents for all classes of vehicles considered in this
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study. Note that the CO2 equivalents used in these tables were provided by the EPA as
9,087 g/gal of fuel for gasoline and 10,097 g/gal for diesel.
7.2 Nominal Runs
Once the models were developed and validated, a series of nominal runs were prepared to
assess the accuracy and robustness of the model. For the conventional vehicles, the nominal
condition was calculated using the same vehicle parameter values, such as for mass and
aerodynamic drag, as the 2010 baseline vehicles. The advanced engine size was then adjusted
to match the baseline 0-60 mph acceleration time, thus defining the nominal displacement for
each advanced engine. In addition, the nominal condition includes use of a baseline six-speed
automatic transmission for all LDV classes and implementation of stop-start technology. In this
way, the nominal condition is placed on a corner of the design space for each LDV class and
therefore, the nominal conditions serve as the reference point for the design space explored by
the DoE simulations.
For the Powersplit and P2 hybrids, the nominal engine size was reduced by 20% from the
conventional nominal engine size to allow for motor assist to match the aforementioned 0-60
mph performance metric. The 20% engine displacement reduction for the Powersplit and P2
hybrids was determined using Ricardo's engineering judgment and an assessment of existing
hybridization strategy. The nominal electric machine size was then set so that the 0-60 mph
acceleration time was matched for the hybrid nominal cases.
It is not possible to provide validation examples of the nominal vehicle models as they represent
predicted 2020 technology. Also, separate models showing the incremental benefits of
individual technologies were not studied as steps to the overall advanced packages. However,
the program team reviewed detailed output data for over one hundred distinct variables at a 10
Hz sampling rate to confirm that all of the nominal runs reflected reasonable real-world vehicle
behavior. After the nominal runs passed these quality checks, Ricardo proceeded to the DoE
simulation phase of the project.
The full table of nominal runs results for the conventional stop-start, P2 hybrid, and Input
Powersplit hybrid vehicle combinations is in Appendix 5, and presents the key output factors
defined in Appendix 4. These summary results and the rest of the simulation output data were
used to assess the quality of the simulation results before executing the DoE simulation matrix,
for example, by assessing power flows to and from the battery over the drive cycle.
8. COMPLEX SYSTEMS MODEL VALIDATION
Complex systems modeling (CSM) is an objective, scientific approach for evaluating several
potential options or configurations for benefits relative to each other and to a baseline. For this
program, the CSM methodology was used to define the design space for LDVs in the 2020-
2025 timeframe, and then to effectively evaluate LDV performance over this large design space.
8.1 Evaluation of Design Space
The purpose of the DoE simulation matrix is to efficiently explore the potential design space for
LDVs in the 2020-2025 timeframe. The simulation matrix was designed to generate selected
performance results, such as fuel consumption or acceleration times, over selected drive cycles.
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The DoE approach allows an efficient exploration of the design space while limiting the number
of runs needed to survey the design space.
For each discrete combination of vehicle class, powertrain architecture, engine, and
transmission in the design space, the continuous input variables, including applied road load
reductions, were varied over the ranges shown in Tables 8.1 and 8.2 for the conventional and
hybrid powertrains, respectively. These continuous input variable ranges are with respect to the
nominal value for each LDV class. In the analysis, continuous input variables are evaluated
using a combination of the design corner points in a two-level full factorial design and design
points within the space based on a Latin hypercube sampling methodology. Note that vehicle
mass is considered independently of the combination of discrete technologies; for example,
switching from an automatic transmission to a DCT does not automatically adjust the vehicle
mass in the simulation.
To size the electric machines, hybrid vehicle simulations were performed with the conventional
vehicle counterparts to assess the overall braking energy over the drive cycles. This knowledge
was then applied to the hybrid models by sweeping the electric machine sizes over the ranges
shown in Table 8.2 until the overall regenerative energy equaled or exceeded 90% of the total
braking energy, excluding the innate vehicle road load losses.
Table 8.1: Continuous input parameter sweep ranges with conventional powertrain.
Parameter
Engine Displacement
Final Drive Ratio
Rolling Resistance
Aerodynamic Drag
Mass
DoE Range (%)
50 125
75 125
70 100
70 100
60 120
Table 8.2: Continuous input variable ranges for P2 and Powersplit hybrid powertrains.
Parameter
Engine Displacement
Final Drive Ratio
Rolling Resistance
Aerodynamic Drag
Mass
Electric Machine Size
DoE Ra
P2 Hybrid
50 150
75 125
70 100
70 100
60 120
50 300
nge (%)
Powersplit
50 125
75 125
70 100
70 100
60 120
50 150
Latin hypercube sampling is a statistical method originally developed by McKay et al. (1979),
used to generate a set of parameter values over a multidimensional parameter space. The
method randomly samples the multidimensional parameter space in a way that provides
comprehensive and relatively sparse coverage for best efficiency. It also allows one to efficiently
continue to fill the multidimensional parameter space by further random sampling. It provides
more flexibility than traditional multi-level factorial designs for assessing a large parametric
space with an efficient number of experiments.
The vehicle simulations were run in batches and the results were collected and processed.
Vehicle fuel economy and performance metrics were recorded as well as diagnostic variables
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such as the total number of gear shifts and the distance traveled during the drive cycle. The
data were reviewed using a data mining tool and outliers were analyzed, and, as necessary,
debugged and re-run. This approach allowed issues to be detected and diagnosed very quickly
within a large amount of data. Once the data were reviewed and approved, response surface
models were generated.
8.2 Response Surface Modeling
Response surface models (RSM) were generated in the form of neural networks. The goal was
to achieve low residuals while not over-fitting the data. Initially, 66% of the data were used for
fitting the model while the remainder was used to validate the response surface model's
prediction performance. Once a good fit was found, all the data were used to populate the RSM.
Each neural network fit contains all of the continuous and discrete variables used in the study
for a given transmission. One neural network fit per transmission was generated to improve the
quality of the fits.
9. RESULTS
The key project results consist of the raw data sets obtained from over 350,000 individual
vehicle simulation cases, the Data Visualization Tool developed to query the response surfaces
based upon the raw data sets, and this report describing these results. These key results are
discussed below. A separate User Guide for the Data Visualization Tool will be released with
the tool.
9.1 Basic Results of Simulation
Each of the simulation cases generated data at 10 Hz2 which allowed evaluation of the
performance of a specific vehicle configuration in the design space over each of the drive
cycles. These results include parameters such as vehicle speed, calculated engine power, and
instantaneous fueling rate. The detailed data from each simulation run were then distilled into
the main output factors of interest, such as acceleration time and fuel economy, that were then
used in the parametric fit of the RSM.
For this study, the main output factors include raw fuel economy and GHG emissions over each
of the drive cycles studied and performance metrics, such as 0-60 mph acceleration times. The
complete list of output factors is listed in Appendix 4.
9.2 Design Space Query
The Design Space Query within the Data Visualization Tool allows the user to assess a specific
vehicle configuration in the design space by selecting a platform, engine, and transmission and
then setting the continuous variables within the design space range. The generated
performance results are then reported in a table that is exportable to Excel. The user can
assess multiple vehicle configurations and compare them in Excel. The tool table also allows
the user to apply spreadsheet formulas for quick, on-the-side computation. An example of the
Design Space Query is shown in Figure 9.1.
2 To maintain manageable file sizes at an adequate level of fidelity, EPA requested that output files be
generated at a 10 Hz sampling rate—far slower than the EasyS process rate—for its own data quality
checks.
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9.3 Exploration of the Design Space
A more comprehensive survey of the design space can be conducted using the Design Space
Analysis in the Data Visualization Tool, which allows the user to assess the performance of
multiple vehicle configurations from a significant portion of the design space simultaneously.
Each design is generated by selecting a vehicle platform, engine, and transmission, and then by
selecting ranges for the continuous input variables. Figure 9.2 shows the screen where the
design space analysis is set up. For each of the continuous variables, values are generated
using a Monte Carlo analysis from a uniform distribution over the range selected.
Once generated, the results at the design points are stored and may be plotted to visualize the
effects of varying vehicle parameters over the design space. By carefully building a design and
varying the parameters, the user can gain an understanding of the effect of each technology
and the interactions between technologies. Figures 9.3-9.5 show examples of plots that
compare two design space analyses. In these cases, the red points are for a Full Size Car with
advanced diesel engine and dry-clutch DCT, whereas the blue points are for a Full Size Car
with stoichiometric Dl turbo engine and automatic transmission. The black point is the 2010
baseline value. For these examples, the engine displacement was varied from 50% to 125% of
nominal, or 0.71 to 1.8 t displacement for the stoichiometric Dl turbo engine and 1.4 to 3.6 t for
the diesel, and the vehicle mass, from 70% to 100% of nominal, or 2800 to 4000lb.
The example in Figure 9.6 compares various configurations of the Standard Car, all with the
EGR Dl Turbo engine but with different powertrains. The two Conventional Stop-Start cases
have the advanced eight-speed automatic and dry-clutch DCT, shown in blue and gray,
respectively. The Powersplit hybrid is shown in green, and the P2 Hybrid, in red. Again, the
black point is the 2010 baseline value. By contrast, the example in Figure 9.7 compares fuel
economy performance across all seven LDV classes. Here, each LDV class has had its engine
displacement and vehicle mass varied from the minimum to the maximum of the design space.
9.4 Identification and Use of the Efficient Frontier
Part of assessing the selected regions of the design space is to find configurations that balance
efficiency and performance. The Data Visualization Tool identifies an Efficient Frontier, which is
the bound of the sampled design space that has the most desirable performance. The user
must first define a dataset using the Design Space Query, described above in Section 9.2, and
then select the Efficient Frontier tab in the Data Visualization Tool. An example of the Efficient
Frontier screen is shown in Figure 9.8. The Efficient Frontier is marked out in red, and the user
can click on the data points along the frontier to discover the vehicle configurations that lie on
the frontier.
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65
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Displacement Scaling (—)
Figure 9.3: Full Size Car Design Space Analysis example. Black point is 2010 baseline;
red points are for advanced diesel and dry-clutch DCT; blue points, Stoichiometric Dl
Turbo with advanced automatic transmission.
450
425
400
375
350
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Figure 9.4: Full Size Car Design Space Analysis example. Black point is 2010 baseline;
red points are for advanced diesel and dry-clutch DCT; blue points, Stoichiometric Dl
Turbo with advanced automatic transmission.
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40
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red points are for advanced diesel and dry-clutch DCT; blue points, Stoichiometric Dl
Turbo with advanced automatic transmission.
100
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90
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Mass Scaling Factor (—)
Figure 9.6: Standard Car design space analysis example comparing powertrains with
EGR Dl Turbo engine. Blue points are with advanced automatic; gray, dry-clutch DCT;
green, Powersplit; and red, P2 Hybrid. Black point is 2010 baseline.
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Computer Simulation of LDV Technologies for GHG Emission Reduction in the 2020-2025 Timeframe
2000 4000 6000 8000
Vehicle Mass (Ib)
10000
12000
Figure 9.7: Full design space example showing all seven vehicle classes using
Stoichiometric Dl Turbo engine and advanced automatic transmission with varying
vehicle mass and engine displacement.
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Computer Simulation of LDV Technologies for GHG Emission Reduction in the 2020-2025 Timeframe
10. RECOMMENDATIONS FOR FURTHER WORK
Ricardo has the following recommendations for further work on this program:
• Thoroughly analyze and simulate turbo lag effects in the advanced, boosted engines
through engine performance simulation tied in with the vehicle models.
• Run the models over additional drive cycles, such as the NEDC, JC08, or the cold
ambient FTP, to understand how the technology packages may apply to other global
regions.
• Expand the design space to mix 2010 baseline engines and transmissions with the
advanced technologies to better understand the relative contributions of engine or
transmission technology to the performance of the advanced vehicles.
• Include additional engines with different technology packages, such as a version of the
Stoichiometric Dl Turbo engine that has a single, fixed cam profile instead of using the
CPS valvetrain.
• Develop correlation models for the P2 and Input Powersplit hybrid powertrains to
establish a baseline within the simulated design space.
• Implement a Two-Mode Powersplit hybrid powertrain to assess the benefits of
hybridization in the larger LDV classes.
• Study the simulation results to understand main and interaction effects between
technologies.
11. CONCLUSIONS
The following conclusions are supported by this program's results:
• An independent, objective, and robust analytical study of the effectiveness of selected
LDV technologies expected to be prevalent in the 2020-2025 timeframe, and their
effects on vehicle performance has been completed.
• A comprehensive review process was completed to identify technologies likely to be
available in the 2020-2025 timeframe and to estimate their future performance given
current trends and expected developments.
• The vehicle performance models were based upon the underlying physics of the
technologies and have been validated with good result to available test data. Quality
assurance checks have been made throughout the study to ensure accuracy of the
trends in the results.
• The Data Visualization Tool allows EPA and other stakeholders to efficiently examine
the design space developed through the program's complex systems modeling approach
and to assess trade-offs between various vehicle configurations and their performance.
The tool provides the necessary functionality to assess specific vehicle designs or more
comprehensively explore the design space.
29 November 2011 Ricardo, Inc. Page 56
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Computer Simulation of LDV Technologies for GHG Emission Reduction in the 2020-2025 Timeframe
12. ACKNOWLEDGEMENTS
Ricardo wishes to acknowledge the contributions of the team that supported the technical work
through the course of the program, which included the following:
• David Boggs, Technical Specialist
• Paul Bosker, Program Manager
• Nick Bouhamdan, Program Manager
• Felipe Brandao, Technology Leader
• Anrico Casadei, Senior Project Engineer
• Mark Christie, Vice President of Engineering Operations
• Jennifer Durfy, Project Engineer and Subject Matter Expert
• Josef Fulem, Senior Fuel Cell Product Engineer
• Keith Gilbert, Project Engineer and Subject Matter Expert
• Daniel Gross, Project Engineer
• Tom Gutwald, Innovations Department Manager
• Stuart Horswill, Chief Engineer and Subject Matter Expert
• Henry Huang, Project Engineer
• Neville Jackson, Chief Technology and Innovations Officer
• Fred Jacquelin, Technical Specialist
• Carl Jenkins, Product Group Director
• Angela Johnson, Principal Engineer
• Neil Johnson, Project Engineer and Subject Matter Expert
• John Kasab, Chief Engineer
• Chris Mays, Project Director and Subject Matter Expert
• Shaun Mepham, Product Group Director
• Richard Osborne, Chief Engineer and Subject Matter Expert
• Pascal Reverault, Principal Engineer and Subject Matter Expert
• Cedric Rouaud, Chief Engineer and Subject Matter Expert
• Daniel Shepard, Associate Engineer
• John Stokes, Gasoline Technical Specialist and Subject Matter Expert
• Qiong Sun, Program Manager
• Wayne Thelen, Chief Engineer and Subject Matter Expert
• Marc Wiseman, Principal (Ricardo Strategic Consulting)
29 November 2011 Ricardo, Inc. Page 57
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Computer Simulation of LDV Technologies for GHG Emission Reduction in the 2020-2025 Timeframe
13. REFERENCES
Anderson, S.R., D.M. Lamberson, T.J. Blohm, and W. Turner, 2005, "Hybrid route vehicle fuel
economy." SAE Technical Paper 2005-01-1164.
Beazley, R., 2010, "EBDI® - Application of a high BMEP downsized spark ignited engine".
Presented at 2010 DEER Conference, Detroit, Mich.
Biltgen, P., T. Ender, and D. Mavris, 2006, "Development of a collaborative capability-based
tradeoff environment for complex system architectures. 44th AIAA Aerospace Sciences Meeting
and Exhibit. AIAA Technical Paper 2006-728
Burress, T.A., C.L. Coomer, S.L. Campbell, L.E. Seiber, R.H. Staunton, and J.P. Cunningham,
2008, "Evaluation of the 2007 Toyota Camry Hybrid Synergy Drive System." ORNL technical
report TM-2007/190.
Coltman, D., J.W.G. Turner, R. Curtis, D. Blake, B. Holland, R.J. Pearson, A. Arden, and H.
Nuglisch, 2008, "Project Sabre: A close-spaced direct injection 3-cylinder engine with
synergistic technologies to achieve low CO2 output." SAE Technical Paper 2008-01-0138.
Gruff, L, M. Kaiser, S. Krause, R. Harris, U. Krueger, M. Williams, 2010, "EBDI®-Application of
a fully flexible high BMEP downsized spark ignited engine." SAE Technical Paper 2010-01-
0587.
Environmental Protection Agency, 2010, "Test Car List Data Files", available from
www.epa.gov/oms/tcldata.htm.
Fiat Powertrain Technologies, S.p.A., 2009, "MultiAir: The ultimate air management strategy".
http://www.fptmultiair.com/flash_multiair_eng/home.htm
Fulem, J., J.J. Kasab, S. Russell, and C.J. Mitts, 2006, "Advanced computational tools for
systems engineering of fuel cell powertrains." Presented at Fuel Cell Seminar, Nov. 2006.
Hellenbroich, G., and V. Rosenburg, 2009, "FEV's new parallel hybrid transmission with single
dry clutch and electric torque support." Aachener Koloquium Fahrzeug- und Motorentechnik
2009 18:1209-1222.
Hohenner, H., 2010, "Current trends on powertrain development - Downsizing and
downspeeding." 4th CTI Symposium on Automotive Transmissions and Drivetrains - North
America, Jun 2010.
Honda Motor Company, 2011, "The VTEC breakthrough: Solving a century-old dilemma".
http://world.honda.com/automobile-technology/VTEC/
Kinnunen, M.J., 2006, Complexity Measures for System Architecture Models. Masters' thesis at
Massachusetts Institute of Technology.
Lumsden, G., D. OudeNijeweme, N. Fraser, and H. Blaxill, 2009, "Development of a
turbocharged direct injection downsizing demonstrator engine". SAE Technical Paper 2009-01-
1503.
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Computer Simulation of LDV Technologies for GHG Emission Reduction in the 2020-2025 Timeframe
Luskin, P., 2010, A Systems Engineering Methodology for Fuel Efficiency and its Application to
a Tactical Wheeled Vehicle Demonstrator. Masters' thesis at Massachusetts Institute of
Technology.
McCarthy, I.P., T. Rakotobe-Joel, and G. Frizelle, 2000, "Complex systems theory: Implications
and promises for manufacturing organizations." Int. J. Manufacturing Technology and
Management, 2(1-7): 559-579.
McKay, M.D.; Beckman, R.J.; Conover, W.J., 1979, "A comparison of three methods for
selecting values of input variables in the analysis of output from a computer code."
Technometrics 21(2): 239-245.
"MSC Easy5 Advanced Controls Simulation", downloaded from
http://www.mscsoftware.com/Products/CAE-Tools/Easy5.aspx. Last accessed 12 Aug 2011
Muta, K., Y. Makoto, and J. Tokieda, 2004, "Development of new-generation hybrid system
THS II - Drastic improvement of power performance and fuel economy." SAE Technical Paper
2004-01-0064.
Ricardo and PQA, 2008, A Study of Potential Effectiveness of Carbon Dioxide Reducing Vehicle
Technologies. EPA Report 420-R-08-004a.
Schaeffler Group, 2010, "Important Facts About UniAir/MultiAir".
http://www.ina.de/content.ina.de/en/press/press-releases/press-details.jsp?id=3429505
Schmuck-Soldan, S., A. Konigstein, and F. Westin, 2011, "Two-Stage Boosting of Spark Ignition
Engines." Internationales Wiener Motorensymposium 2011 Europe S.r.l., Torino.
Shaw, J.R., 2009, "Testimony to Joint EPA/NHTSA Hearing on Proposed Rulemaking to
Establish Light Duty Vehicle Greenhouse Gas Emissions Standards and Corporate Average
Fuel Economy Standards". Downloaded from www.autosteel.org last accessed 27 Oct 2009
Staunton, R.H., C.W. Ayers, L.D. Marlino, J.N. Chiasson, T.A., Burress, 2006, "Evaluation of
2004 Toyota Prius Hybrid Electric Drive System". ORNL technical report TM-2006/423.
Turner, J.W.G., R.J. Pearson, R. Curtis, and B. Holland, 2009, "Sabre: A cost-effective engine
technology combination for high efficiency, high performance and low CO2 emissions." Low
Carbon Vehicles 2009: Institution of Mechanical Engineers (IMechE) conference proceedings.
Weissier, P., 2011, "Engine stop-start deployment in U.S. faces challenge from loss of A/C."
AEI, 5 July 2011, pp. 10-12.
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Computer Simulation of LDV Technologies for GHG Emission Reduction in the 2020-2025 Timeframe
APPENDICES
Appendix 1, Abbreviations
AMI Automated manual transmission LOT
ARE California Air Resources Board LDV
BEV Battery electric vehicle LEV
BMEP Brake mean effective pressure LHDT
BSFC Brake specific fuel consumption LNT
Cl Compression ignition MPV
CPS Cam profile switching NA
CSM Complex systems modeling NMEP
CVT Continuously variable transmission NOx
DCT Dual clutch transmission NVH
Dl Direct injection OEM
DoE Design of experiments ORNL
DVA Digital valve actuation OTAQ
EGR Exhaust gas recirculation
EPA United States Environmental PAS
Protection Agency PFI
EPAS Electric power assisted steering PHEV
EV Electric vehicle PMEP
FCEV Fuel cell electric vehicle PQA
FEAD Front end accessory drive RSM
FIE Fuel injection equipment SCR
FMEP Friction mean effective pressure SI
GHG Greenhouse gas SME
ICCT International Council on Clean SOC
Transportation SULEV
ICE Internal combustion engine V2I
IMEP Indicated mean effective pressure V2V
KERS Kinetic energy recovery system VA
Light-duty truck
Light-duty vehicle
Low emissions vehicle
Light heavy-duty truck
Lean NOx trap
Multi-purpose vehicle
Naturally aspirated
Net mean effective pressure
Nitrogen oxides
Noise, vibration, and harshness
Original equipment manufacturer
Oak Ridge National Laboratory
Office of Transportation and Air
Quality
Power assisted steering
Port fuel injection
Plug-in hybrid electric vehicle
Pumping mean effective pressure
Perrin Quarles Associates
Response surface model
Selective catalytic reduction
Spark ignited
Subject matter expert
State of charge
Super ultra low emissions vehicle
Vehicle to infrastructure
Vehicle to vehicle
Valve actuation
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Appendix 2, Assessment of Technology Options
At the start of the program, Ricardo and EPA, with input from the Advisory Committee,
developed a comprehensive list of technology options for further consideration by Ricardo's
Subject Matter Experts. The technologies are listed below. The technologies considered further
for assessment are in the related document "Assessment of Technology Options" (Ricardo
reference RD.11/ 342305.1), included as Attachment A.
Engine technologies considered included the following:
• Engine downsizing
• Direct injection
• Turbocharging
• Valvetrain technologies and subsystems, including
o CPS valvetrains
o DVA or variable valve timing (VVT) valvetrains
• Stratified charge Dl
• Homogeneous charge compression ignition (HCCI) or controlled auto-ignition (CAI)
combustion
• Exhaust energy recovery, including
o Mechanical turbo-compounding
o Electrical turbo-compounding
o Thermoelectric devices
• Second-generation biofuels
• Friction reduction technologies
• Closed-loop combustion control
• Adjustments to compression ratio
• Advanced boosting technologies
• Enhanced EGR and charge air cooling
• Pre-turbine catalysis
• Calibration optimization for low GHG emissions
• Narrow speed range operation
• Optimization of engines for use with hybrid powertrains
Engine configurations considered included the following:
• Stoichiometric Dl turbocharged
• Lean Dl turbocharged
• High-load EGR engines
• Multi-mode (2 stroke-4 stroke)
• Engines optimized for hybrid powertrains, including
o Stop-start powertrains
o Full hybrid powertrains
Hybrid powertrain technologies, including
• Micro hybrid or stop-start system
• Integrated belt starter-generator (BSG)
• Integrated crank starter-generator (ISG) or Integrated motor assist (IMA)
• P2 parallel hybrid powertrain
• Input Powersplit hybrid powertrain
• Two-mode Powersplit hybrid powertrain
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Computer Simulation of LDV Technologies for GHG Emission Reduction in the 2020-2025 Timeframe
• Series hybrid
• Parallel hydraulic hybrids
Transmission technologies, including
• Advanced automatic transmissions
• AMTs
• CVTs
• DCTs
• Launch devices
o Wet clutch
o Damp clutch
o Dry clutch
o Multi-damper torque converter
o Magnetic clutch
• Shifting clutch technology
• Smart kinematic design
• Dry sump
• Efficient components
• Super finishing
• Lubricant improvements
Vehicle technologies, including
• Mass reduction through use of
o Advanced high strength steels
o Aluminum alloys
o Magnesium alloys
o Plastics and fiber-re info reed composites
• Mass reduction through component optimization
• Passive and active aerodynamics improvements
• Active aerodynamics systems
• Thermoelectric generators
• HVAC system load reduction
• Tire rolling resistance
• Intelligent cooling systems
• Electric PAS
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Computer Simulation of LDV Technologies for GHG Emission Reduction in the 2020-2025 Timeframe
Appendix 3, Baseline Vehicle Parameters and Runs Results
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Computer Simulation of LDV Technologies for GHG Emission Reduction in the 2020-2025 Timeframe
Appendix 4, Output Factors for Study
Raw fuel economy in miles per US gallon and GHG emissions in grams of CO2 per mile over
• FTP75
• HWFET
• US06
• HWFET and FTP combined
Acceleration performance metrics, including
• 0-10 mph acceleration time
• 0-30 mph acceleration time
• 0-50 mph acceleration time
• 0-60 mph acceleration time
• 0-70 mph acceleration time
• 30-50 mph acceleration time
• 50-70 mph acceleration time
• Top speed at 5% grade
• Top speed at 10% grade
• Velocity at 1.3 sec
• Velocity at 3.0 sec
• Distance at 1.3 sec
• Distance at 3.0 sec
• Maximum grade at 70 mph at GCW
• Maximum grade at 60 mph at GCVW (LOT and LHDT only)
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Computer Simulation of LDV Technologies for GHG Emission Reduction in the 2020-2025 Timeframe
Appendix 5, Nominal Runs Results
The table lists the baseline (2010) vehicles first, followed by results by vehicle class. The P2
Hybrids have an electric machine size listed, and all use the OCT. There were no Conventional
Stop-Start nominal runs that used the OCT. For the Input Powersplit hybrids, only the traction
motor size is listed, as the generator size is a function of the engine and traction motor sizes.
Abbreviations used exclusively in the following table of Nominal Runs Results include the
following:
Baseline The 2010 baseline engine for the given vehicle class
Stoich DIT Stoichiometric Dl Turbo engine
Lean DIT Lean-Stoichiometric Dl Turbo engine
EGR DIT EGR Dl Turbo engine
Adv Diesel Advanced (2020) diesel
Atk CS Atkinson cycle engine with CPS
Atk DVA Atkinson cycle engine with DVA
AT6 Six-speed automatic transmission (baseline or advanced, as appropriate)
ATS Eight-speed automatic transmission (advanced only)
DCT Dry or wet clutch DCT, per simulation matrix.
PS Powersplit planetary gearset
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Computer Simulation of LDV Technologies for GHG Emission Reduction in the 2020-2025 Timeframe
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29 November 2011
Ricardo, Inc.
Page 66
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Computer Simulation of LDV Technologies for GHG Emission Reduction in the 2020-2025 Timeframe
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29 November 2011
Ricardo, Inc.
Page 67
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Computer Simulation of LDV Technologies for GHG Emission Reduction in the 2020-2025 Timeframe
DISCLAIMER
Ricardo Inc. has taken all reasonable care in compiling the analyses and recommendations
provided in this report. However, the information contained in this report is based on information
and assumptions provided by the client or otherwise available to Ricardo which, in all the
circumstances, is deemed correct on the date of writing. Ricardo does not assume any liability,
provide any warranty or make any representation in respect of the accuracy of the information,
assumptions, and consequently the analyses and recommendations contained in this report.
The report has been compiled solely for the client's use.
Any results of analysis and calculation are intended to be part of subsequent decision-making
during design, development and problem-solving stages. Although analysis may reduce the
effort required to validate a product through testing prior to production, such results shall not be
relied on as a validation in its own right.
Analysis and calculations which are intended to predict physical behaviors are inherently
theoretical in nature as they are subject to a range of assumptions and approximations. Physical
behaviors and the measurements of those behaviors may vary for a variety of factors, some
being outside the control of Ricardo or the capability of the predictive methodology used by
Ricardo. Therefore, where any such predictions are subsequently compared with measured
data or physical behavior, it is to be expected that differences will be apparent.
29 November 2011 Ricardo, Inc. Page 68
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Computer Simulation of LDV Technologies for GHG Emission Reduction in the 2020-2025 Timeframe
ATTACHMENT A
Attachment A is the document "Assessment of Technology Options", which includes Ricardo
SME assessments of the technologies considered in study "Computer Simulation of Light Duty
Vehicle Technologies for Greenhouse Gas Emission Reduction in the 2020-2025 Timeframe".
These assessments were made of the technologies listed in Appendix 2.
29 November 2011 Ricardo, Inc. Page 69
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RICARDO
Assessment of Technology Options
Technologies considered in study "Computer Simulation of Light
Duty Vehicle Technologies for Greenhouse Gas Emission Reduction
in the 2020-2025 Timeframe"
Date
Report
Project
Prepared for
Report by
Approved
30 September 2011
RD. 11/342305.1
CG001019
EPA Office of Transportation and Air Quality
Jennifer Durfy
Stuart Horswill
Chris Mays
Richard Osborne
John Stokes
Wayne Thelen
John J. Kasab
DELIVERING VALUE THROUGH INNOVATION & TECHNOLOGY
www.ricardo.com
RD.11/342305.1
-------
Outline
RICARDO
Introduction
Spark ignited engine technologies
Diesel engine technologies
Hybrid vehicle technologies
Transmission technologies
Vehicle technologies
Conclusions
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
-------
Introduction
RICARDO
The following technology assessments were discussed by Ricardo, EPA, and
the Advisory Committee at the start of the study, "Computer Simulation of Light
Duty Vehicle Technologies for Greenhouse Gas Emission Reduction in the
2020-2025 Timeframe11
Purpose of the assessments was to evaluate a large set of potential future
technologies against the following criteria:
Effectiveness of Technology
- Availability of Technology in 2020-2025
- Market Penetration of Technology in 2020-2025
Long-Term Cost Viability
Current Technology Maturity
Assessments used the scale on the following slide and were based on the
Ricardo Subject Matter Experts' experience with the systems considered
Based on the evaluation and discussion, a subset of these technologies was
included in the final study.
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Details of the rating system
RICARDO
Effectiveness of Technology (tank to wheels basis)
1 = Worst = no C02 benefit
• 2 = 1% C02 benefit
• 5 = 5% C02 benefit
8 = 10% C02 benefit
• 10= Best = >20% C02 benefit
Availability of Technology in 2020-2025
1 = University Research Laboratory
• 3 = Technology available but not in vehicles
• 4 = First Prototype in vehicles
6 = In Fleet Trials
• 7 = First entry into market
10 = Predominant technology in market place
Market Penetration of Technology in 2020-2025
1 = Worst = Demonstrated technology by 2025
• 3 = Only in niche applications
5 = Available, but not widespread (>5% of market)
7 = Mass-market availability (>10% of market)
10 = Best = Widespread (>25% of market)
Long-Term Cost Viability
• 1 = WORST = no pathway to long-term cost viability
3 = Needs to "cross commercialization chasm"
• 5 = Pathway to volume production costs
• 7 = Return on investment clear
10 = Profitable in 2020-2025
Current Technology Maturity
1 = University Research Laboratory
• 3 = Technology available but not in vehicles
• 4 = First Prototype in vehicles
6 = In Fleet Trials
• 7 = First entry into market
10 = Predominant technology in market place
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
-------
Outline
RICARDO
Introduction
Spark ignited engine technologies
Diesel engine technologies
Hybrid vehicle technologies
Transmission technologies
Vehicle technologies
Conclusions
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
-------
Technology Assessment-SI Engines
Baseline Gasoline Engines
RICARDO
Technology and Status
Ratings of Technology
Concept: The baseline gasoline engines for 2020-2025 light-duty vehicles in
the US market are a range of naturally-aspirated port fuel-injected (PFI)
engines, featuring dual-independent cam phaser (VVT) systems
Base Functioning: The baseline vehicles will achieve a fleet average
emissions level of SULEV2 (approximately EPA Tier 2 Bin 2)
CO2 Benefit: Baseline (>35.5 mpg fleet average)
Costs: Baseline - powertrain and aftertreatment cost of ~$1500-$2000 for
standard car segment
Technology Applicability
The following vehicle classes are the subject of this study:
Small car (Ford Focus)
Standard car (Toyota Camry)
Small MPV (Saturn Vue)
Full-size car (Chrysler 300C)
Large MPV (Dodge Grand Caravan)
Truck (Ford F150)
Heavy light-duty truck (Ford F250/F350)
(worst)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
10
(best)
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
-------
Outline
RICARDO
Introduction
Spark ignited engine technologies
Downsized engines
Advanced valvetrains
Combustion systems and fuels
Engines for hybrid vehicles
Diesel engine technologies
Hybrid vehicle technologies
Transmission technologies
Vehicle technologies
Conclusions
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Technology Assessment-SI Engines
Stoichiometric Direct-Injection Turbocharged Engines
RICARDO
Technology and Status
Ratings of Technology
Concept: Downsizing describes the replacement of a naturally-aspirated engine
with a smaller-displacement turbocharged engine, having equivalent torque and
power
Base Functioning: Downsizing reduces pumping work by shifting operating
points to higher load factors, and can also produce reductions in frictional losses
CO2 Benefit: Drive-cycle benefit of 8-10%
Costs: 15-25% increase in engine and aftertreatment cost
Technology Applicability
Downsized Dl turbo engines are applicable in all light-duty vehicle classes
Likely to predominate in mid-size vehicles
As a high compression ratio is maintained, downsized Dl turbo engines provide
fuel economy benefits across the majority of the operating map
As a result, both city and highway fuel economy will benefit
(worst)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
-------
Technology Assessment-SI Engines
Lean Direct-Injection Turbocharged (LDIT) Engines
RICARDO
Technology and Status
Ratings of Technology
Concept: In the LDIT concept the octane requirement is controlled using direct
injection and lean operation at full load
Base Functioning: LDIT engines combine the downsizing benefits described
on the previous slide with the additional efficiency benefit of homogeneous lean
operation at high load
CO2 Benefit: Drive-cycle benefit of 20-22%
Costs: 50-60% increase in engine and aftertreatment cost
1 -
(worst)
Effectiveness |
Availability |
Market •
Penetration '
Long-Term •
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* 10
(best)
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Technology Applicability
Visualization
LDIT engines are applicable to all vehicle classes
Likely to predominate in mid-size vehicles and premium vehicles
As a high compression ratio is maintained and lean operation is applied at all
conditions LDIT engines provide fuel economy benefits across the majority of
the operating map
As a result, both city and highway fuel economy will benefit
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Technology Assessment-SI Engines
High-Load EGR Engines
RICARDO
Technology and Status
Ratings of Technology
Concept: This downsized Dl engine concept is analogous to LDIT, but octane
requirement is controlled by EGR dilution at full load rather than lean operation.
Base Functioning: High-load EGR engines combine the benefits of downsizing
described previously with the additional efficiency improvement of EGR dilution
at high load
CO2 Benefit: Drive-cycle benefit of 15-18%
Costs: 40-45% increase in engine and aftertreatment cost
Technology Applicability
High-load EGR engines are applicable to all vehicle classes
As a high compression ratio is maintained and EGR dilution is applied at all
conditions, High-load EGR engines provide fuel economy benefits across the
operating map
As a result, both city and highway fuel economy will benefit
(worst)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
tf I
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Technology Assessment-SI Engines
Two-Stroke/Four-Stroke (2S-4S) Switching Engines
RICARDO
Technology and Status
Ratings of Technology
Concept: The vast majority of passenger cars use the four-stroke cycle, but
some characteristics of two-stroke engines—especially high specific torque—
remain attractive for automotive application. 2S-4S engines combine a
combustion system capable of operating as both two-stroke and four-stroke with
advanced valvetrain and boosting systems.
Base Functioning: 2S-4S engines offer the greatest opportunity for engine
downsizing, and hence improvement in efficiency
CO2 Benefit: Drive-cycle benefit of 25-27%
Costs: 70-80% increase in engine and aftertreatment cost
Technology Applicability
2S-4S engines operate in four-stroke mode for the majority of drive-cycle
operation, so the emissions and fuel economy characteristics are those of a
heavily downsized 4S Dl turbo engine
2S-4S engines are most likely to be applied in premium vehicle segments
(worst)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
CG001019
Prepared for SRA and EPA
30 September 2011
RD.11/342305.1
-------
Outline
RICARDO
Introduction
Spark ignited engine technologies
Downsized engines
- Advanced valvetrains
Combustion systems and fuels
Engines for hybrid vehicles
Diesel engine technologies
Hybrid vehicle technologies
Transmission technologies
Vehicle technologies
Conclusions
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
-------
Technology Assessment-SI Engines
Cam-Profile Switching Engines
RICARDO
Technology and Status
Ratings of Technology
Concept: Cam-profile switching (CPS) systems allow selection between two or
three cam profiles by means of a hydraulically-actuated mechanical system
CPS systems have been developed by a number of Japanese and European
OEMs, such as the Honda VTEC, Mitsubishi MIVEC, Porsche VarioCam and
Audi Valvelift (pictured)
Base Functioning: CPS systems can be optimised either to improve low-speed
torque, or to improve fuel economy by reducing pumping losses at light load
CO2 Benefit: Drive-cycle benefit of 5-7%
Costs: 8-10% increase in engine and aftertreatment cost
Technology Applicability
Cam-profile switching systems are applicable in all light-duty vehicle classes
CPS systems produce most fuel economy benefit for part-load operation, so
most benefit occurs for city driving and less for highway use
(worst)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
10
(best)
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
-------
Outline
RICARDO
Introduction
Spark ignited engine technologies
Downsized engines
Advanced valvetrains
Combustion systems and fuels
Engines for hybrid vehicles
Diesel engine technologies
Hybrid vehicle technologies
Transmission technologies
Vehicle technologies
Conclusions
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
-------
Technology Assessment-SI Engines
Stoichiometric Direct-Injection Engines
RICARDO
Technology and Status
Ratings of Technology
Concept: Stoichiometric, homogeneous direct-injection gasolines operate in a
very similar manner to port fuel-injected engines, except that fuel is injected
directly into the cylinder. GDI engines were first introduced in Japan in 1996,
and a significant number of new gasoline engines now feature direct injection.
Base Functioning: The application of direct injection produces modest fuel
economy benefits, resulting from the ability to apply higher compression ratio.
CO2 Benefit: Drive-cycle benefit of ~3%
Costs: 8-10% increase in engine and aftertreatment cost
Technology Applicability
Stoichiometric Dl engines are applicable in all vehicle classes
The higher compression ratio facilitated by Dl improves both part-load and high-
load efficiency, and therefore both highway and city fuel economy
10
(worst)
Effectiveness • (3
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
(best)
Visualization
CG001019
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30 Seotember 2011
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Technology Assessment-SI Engines
Stratified Charge Direct-Injection Engines
RICARDO
Technology and Status
Ratings of Technology
Concept: In stratified-charge engines the fuel is injected late in the
compression stroke with single or multiple injections. The aim is to produce an
overall lean, stratified mixture, with a rich area in the region of the spark plug to
enable stable ignition.
Base Functioning: Stratified lean operation allows the gasoline engine to
operate unthrottled, eliminating the majority of pumping losses.
CO2 Benefit: Drive-cycle benefit of 8-1 0%
Costs: 15-25% increase in engine and aftertreatment cost
Technology Applicability
As a result of the FIE and aftertreatment costs, lean Dl systems are most
applicable in premium vehicles
As the fuel economy benefit derives from the reduction of pumping work, lean
Dl engines produce most improvement in city driving
There is limited benefit for highway driving
(worst)
Effectiveness
Availability
Market
Penetration
Long-Term
Viability
Current
Maturity
Visualization
10
(best)
CG001019
Prepared for SRA and EPA
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Technology Assessment-SI Engines
HCCI/CAI Combustion
RICARDO
Technology and Status
Ratings of Technology
Concept: Homogeneous charge compression ignition (HCCI), also known as
controlled auto-ignition (CAI) combustion are distinct from the conventional SI
and Cl engine operating modes
In the idealized case HCCI/CAI combustion initiates simultaneously at
multiple sites within the combustion chamber, and there is little or no flame
propagation
Base Functioning: Dual mode operation, with HCCI/CAI at part-load, and SI
for high-load, idle and starting
CO2 Benefit: Drive-cycle benefit of 2-10% (depending on whether the benefits
of the constituent technologies are included or not)
Costs: 20-30% increase in engine and aftertreatment cost
Technology Applicability
HCCI/CAI combustion is unlikely to be an attractive technology for light-duty
gasoline vehicles in 2020-2025
The operating envelope for HCCI/CAI combustion is very limited, and the
additional benefits over the necessary constituent technologies (advanced
valvetrains, GDI etc.) are also small
(worst)
Effectiveness • (3
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
(best)
Visualization
500 1000 1500 2000 2500 3000 3500 4001
Engine Speed [rev/min]
CG001019
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Technology Assessment-SI Engines
Exhaust Energy Recovery
RICARDO
Technology and Status
Concept: Exhaust energy recovery encompasses a number of technologies,
such as turbo-compounding and thermoelectric devices
In turbo-compounding a radial turbine is connected through a mechanical
transmission directly to the crankshaft
Base Functioning: Turbines are generally sized to recover energy at high load
operation; a variable-speed transmission between engine and turbine can be
used to improve the efficient operating range
CO2 Benefit: Turbo-compounding has a drive-cycle benefit of 3-5%
Costs: Not established for light-duty vehicles
Technology Applicability
Turbo-compounding is currently only applied to premium long-haul trucks
In 2020 it will still be most applicable to the heavy light-duty truck segment,
and the benefits will be reduced in comparison to heavy-duty vehicles
Ratings of Technology
10
(worst)
(best)
Effectiveness | uy |
Availability | Zi72^B
Penetration
Long-Term
Cost Viability
Current
Maturity
•$
Visualization
Energy in Fuel
Energy loss in the exhaustgas - 30%
Recovery of more exhaust
Usable Engine Energy
CG001019
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Technology Assessment-SI Engines
Second-Generation Biofuels
RICARDO
Technology and Status
Ratings of Technology
Concept: Second-generation biofuels refer to fuels coming from non-food
sources (in this case gasoline-like fuels)
Base Functioning: Wherever possible biofuels should operate in a manner
identical to conventional gasoline
Increasing blending of conventional gasoline and biofuels is likely to occur
CO2 Benefit: The C02 benefits from the use of biofuels are complex and
disputed
Costs: There is no significant engine cost associated with the use of single-fuel
biofuels (although appropriate materials must be applied in the fuel system)
Technology Applicability
Biofuels are applicable to all vehicle classes
Tank-to-wheels fuel economy for biofuels is similar to that for conventional
gasoline engines - benefits occur from the higher octane number of ethanol-
based fuels
Additional C02 benefits can be attributed to biofuel use if the complete life-cycle
is considered (cellulosic ethanol, etc.)
10
(worst) (best)
Effectiveness ^H <5)
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
n v s^ ^
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CG001019
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30 Seotember 2011
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Outline
RICARDO
Introduction
Spark ignited engine technologies
Downsized engines
Advanced valvetrains
Combustion systems and fuels
Engines for hybrid vehicles
Diesel engine technologies
Hybrid vehicle technologies
Transmission technologies
Vehicle technologies
Conclusions
CG001019
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Technology Assessment-SI Engines
Engines Optimized Micro-Hybrid (Stop-Start) Vehicles
RICARDO
Technology and Status
Ratings of Technology
Concept: Application of stop-start or micro-hybrid concepts requires only very
minor changes in base engine architecture. Typically a belt-driven starter-
generator is applied in place of a separate starter motor and alternator.
Base Functioning: See hybrid vehicle slides
CO2 Benefit: See hybrid vehicle slides
Costs: Base engine costs are largely unchanged for stop-start systems.
Additional engineering cost is required to implement the stop-start calibration.
1 -
(worst)
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Visualization
Stop-start should applied in all vehicle segments for the 2020 timeframe
Given hybrid inititives, it is likely that most new engine development projects will
consider integrating stop start functionality in program.
CG001019
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Technology Assessment-SI Engines
Engines Optimized for Full Hybrid Vehicles
RICARDO
Technology and Status
Ratings of Technology
Concept: In hybrid electric vehicle applications the gasoline engine can be
optimised for use in the limited modes required by the full hybrid powertrain.
Base Functioning: See hybrid vehicle slides
CO2 Benefit: Strong function of degree of limited operating conditions.
Costs: Base engine costs may be slightly reduced for hybrid vehicle
applications through the use of lower specification engines.
Technology Applicability
Engine technology optimization for hybrid powertrains in infancy. Clear trend
towards system level optimization to obtain best overall performance.
Hybrid features such as stop-start, CVT operation, electrical launch, and
electrical assist provide an oportuntity to optimize the engine system in ways
not offered by conventional drivelines.
Electrical assist offers opportunity to reduce engine size and specific power in
hybrid vehicle and utilize lower specific power/ increased BSFC technologies
(worst)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
10
(best)
CG001019
Prepared for SRA and EPA
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Technology Assessment-SI Engines
SI Engine Technology Applicability
RICARDO
Please note that the applicability of hybrid powertrains is covered elsewhere in
this report
Vehicle
Classification
Small Car (Ford Focus)
Standard Car (Toyota Camry)
Small MPV (Saturn Vue)
Full-sized Car (Chrysler 300C)
Large MPV (Dodge Grand Caravan)
Truck (Ford F1 50)
Heavy light-duty truck (Ford F250/F350)
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CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Outline
RICARDO
Introduction
Spark ignited engine technologies
Diesel engine technologies
Hybrid vehicle technologies
Transmission technologies
Vehicle technologies
Conclusions
CG001019
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Technology Assessment- Diesel Engines
Technology Area Overview
RICARDO
For this technology area, we have the following thoughts for the situation in
2020-2025:
Diesel Technology will continue to be developed driven largely by the European
market but a gradual penetration will be seen in the US market
Improvement is required in technology cost, particularly turbocharging and
aftertreatment for significant penetration
US market penetration for domestic producers is assumed to commence from
the heavier vehicles in the study cascading down in size as technology matures,
acceptance improves, and CO2 legislation drives incremental fleet actions
Baseline is T2B5 (LEV II) applications currently in market
Represents ca. 20% CO2 benefit from current baseline SI engine
2020 diesel engines assumed to meet LEV III (approximately current
SULEV II) emissions
CG001019
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Technology Assessment- Diesel Engines
Technology Status - Diesel Powertrain
Consideration made across all sectors of study
RICARDO
Technology has very low take rate in US market in passenger car and light duty
truck applications versus Europe
Product typically only available in imported passenger car (e.g., VW, Audi,
BMW and Mercedes)
Domestic Product generally offered in LHDT (e.g. Ford Superduty)
European Diesel share is half of market and covers all product families from
sub-B (Fiat 500 class) to LHDT (Dodge Sprinter Class)
European Market has a competitive CO2 driver leading to Diesel green
branding (e.g. Ford Econetic, Mercedes Bluetec, VW Bluemotion)
European Diesel Technology has seen many technology advances
Sequential turbocharging
Combustion correction techniques (e.g. UEGO, cylinder pressure)
Large EGR coolers with hot gas bypass
Third generation FIE - 2000 Bar and multiple injections
Mature DPF technology
SCR technology applied
Advanced materials - Al alloy heads and blocks, CGI blocks
CG001019
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Technology Assessment- Diesel Engines
Diesel Technology List for US Applications
RICARDO
Closed Loop Combustion Control
Reduced Compression Ratio
Advanced Boosting Technologies
Enhanced EGR and Charge Air Cooling
Variable Valve Timing (With Application To Vary Compression Ratio)
Pre-Turbine Catalysis
Electric Turbo-Compounding
Calibration "System" Optimization for CO2 (Engine + Trans + Aftertreatment)
Narrow Speed Range Operation
System Integration at Engine Level
Engine Downsizing - no slide - duplication with SI Engine
Engine Friction Reduction - no slide
CG001019
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Technology Assessment- Diesel Engines
Closed Loop Combustion Control
RICARDO
Technology and Status
Ratings of Technology
Concept: Provide feedback from combustion by means of direct cylinder
pressure measurement and analysis in EMS
Base Functioning: Measure cylinder pressure during combustion to provide
feedback for air, EGR, and fuel injection control to minimize error and correct for
fuel quality allowing better trade-off for C02 emissions versus NOx and PM
CO2 Benefit: <1% from maintaining optimal combustion and facilitates further
combustion optimization
Costs: Added variable costs for glowplug, added inputs and processing power
in engine control unit. Additional development time will be required to
characterize the signal responses and tune calibration correction responses
Technology Applicability
• Technology is applicable to light duty diesel applications commonly fitted with
glowplugs. For heavier duty applications not engineered for glowplug alternate
head gasket technology would need to be employed
• Highway benefits - closed loop combustion feedback allows for real world benefit
plus closer margin between legal limits and development targets allowing further
C02 combustion optimization
• City benefits - Further real world benefit available from combustion correction
during transient events
Other - lower cylinder to cylinder variation
(worst)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
10
(best)
1. Plug
2. High voltage connection
3. Circuit board with electronics
4. Gasket
5. Measuring diaphragm
6. Glow plug body
7. Glow plug heating rod
Picture: www.beru.com
CG001019
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30 Seotember 2011
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Technology Assessment- Diesel Engines
Reduced Compression Ratio
RICARDO
Technology and Status
Ratings of Technology
Concept: Reduction of the compression ratio reduces the peak firing pressure
of the engine. This reduces the pumping losses and allows for higher specific
power to be achieved
Base Functioning: Pumping losses contribute to the total frictional losses
(FMEP) of an engine. Reduction of the losses means less fuel energy is wasted
resulting in higher fuel efficiency
CO2 Benefit: 1% per ratio plus additional from downsizing opportunity
Costs: Reduced compression ratio requires additional effort to start the
engine in colder ambient conditions. An enablerfor significant compression ratio
reduction would be increased starter energy availability allowed by high voltage
hybrid ISG systems
Technology Applicability
Applicable to Diesel ISG applications to enable increased cranking speed for start
performance
Highway benefits - Increased specific power from the engine enables engine
downsizing. Reduced pumping loss gives benefit across the full speed and load
range
City benefits -As pumping losses are a greater proportion of part load operation
the benefit should be more marked in city operation
Idle-stop benefits - Idle fuelling will be reduced although pre-cursor of ISG
enables full stop-start benefit
(worst)
Effectiveness • (3
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
(best)
Visualization
Not
Applicable
CG001019
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Technology Assessment- Diesel Engines
Advanced Boosting Technologies
RICARDO
Technology and Status
Ratings of Technology
Concept: Improvements in air handling through a suite of boosting
technologies either standalone or in combination
Base Functioning: Provision of higher specific torque and power to enable
downsized engines. Technologies include eBoost (e-machine in CHRAor
electrical separation by e-Turbine and e-Compressor); supercharging (advances
to avoid variable drive); variable nozzle compressor
CO2 Benefit: 2% (more if engine downsized for equivalent performance)
Costs: Increase in turbocharger air system matching and development time,
increased complexity in engine controller. Variable cost of turbocharger doubles
plus additional air cooling requirement, sensors and actuators
Technology Applicability
• Technology applicable to all sectors of diesel application
• Highway benefits - improved transient response from engine allows downsizing.
More air allows improved emission performance for NOx and PM control giving
leeway for C02 reduction.
• City benefits - much improved transient performance allowing downsizing.
Operation in more efficient area of turbocharger map gives more noticeable C02
benefit in city driving
In conjunction with enhanced EGR allows for premixed or homogeneous
combustion in part load operation for very clean emissions. Design can facilitate
the use of pre-TC catalyst for quick aftertreatment light-off
10
(worst)
Effectiveness • (3
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
(best)
Visualization
Picture: http://honeywellbooster.com
CG001019
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30 Seotember 2011
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Technology Assessment- Diesel Engines
Enhanced EGR Flow & Cooling
(Plus Increased Charge Air Cooling)
RICARDO
Technology and Status
Ratings of Technology
Concept: Low Pressure EGR Circuit for increased EGR flow rate in conjunction
with separate low temperature cooling circuit to cool EGR and provide additional
charge air cooling
Base Functioning: Increased EGR and cooler charger enables homogeneous,
fully premixed and partially premixed combustion concepts. These concepts
reduce NOx and PM emissions allowing more margin for C02 optimization.
Lower charge temperature provides a larger P-V area and increases specific
power and economy
CO2 Benefit: 2-4% from combined emission and cooling benefit
Costs: Increased development cost for EGR and cooling system packaging.
Additional work to optimize cooling pack. EGR cost increases 40-50% plus
incremental costs for additional cooling system components and material
revisions necessary to cope with corrosive environment in charge cooler with
EGR present
Technology Applicability
Applicable to Light Duty Chassis Certification Applications requiring EGR at low
speed and load:
Highway benefits - Fuel economy improvement from increased charge cooling
and improved compressor efficiency (EGR flows through TC compressor)
City benefits - Significant emission benefit allowing combustion to be optimized
more for C02. Compressor efficiency improved for reduced pumping loss
A significant challenge remains for TC compressor durability with heavy EGR flow
rates
10
(worst) (best)
Effectiveness • (4)
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
Picture: VWTech Report
29. Internationales Wiener MotorensvmDosium 2008
CG001019
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Technology Assessment- Diesel Engines
Variable Valve Timing
(With Application To Vary Compression Ratio)
RICARDO
Technology and Status
Concept: Variable Valve Events enable valve events to be optimzed for
oeprating point and also enable effective compression ratio variation
Base Functioning: Intake and Exhaust Valve Events varied for rapid
aftertreatment warm-up and best breathing at operating condition rather than
global optimization. With more complex system, compression ratio can also be
varied to reduce frictional losses and increase specific power
CO2 Benefit: 1-2% from warm-up & improved breathing. Additional gain if
aftertreatment warmup creates NOx advantage to be used for C02 benefit
Costs: Costs increase for valvetrain technology with some offset in
aftertreatment cost. Additional development cost to develop for diesel engine
application with incremental engine controller costs for drive circuits
Technology Applicability
• Applicable to complete diesel line-up from small car to MDV
• Highway benefits - Increased specific power from the engine enables engine
downsizing. Reduced pumping loss gives benefit across the full speed and load
range
• City benefits -As pumping losses are a greater proportion of part load operation
the benefit should be more marked in city operation
• Idle-stop benefits - ability to raise compression ratio allows stop start to be more
readily employed than reduced compression ratio alone as ISG is not necessary
for restart
Ratings of Technology
10
(worst)
Effectiveness
Availability
Market
Penetration
(best)
Long-Term • A
V
Cost Viability
Current
Maturity
Visualization
Picture: Valeo e-'
CG001019
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30 Seotember 2011
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Technology Assessment- Diesel Engines
Pre-Turbine Catalysis
RICARDO
Technology and Status
Ratings of Technology
Concept: Small Oxidation Catalyst (DOC) is placed before first turbocharger
very close to the engine
Base Functioning: Small pre-turbine catalyst with low thermal inertia lights off
quickly allowing further exotherm to warm up rest of aftertreatment more rapidly.
Reduced warm-up will require lower use of fuel for heating strategies reducing
C02 emissions
CO2 Benefit: <1 % - more for cold start cycles.
Costs: Additional cost for pre-turbine catalyst precious metal partially offset
by reduced precious metal in remainder of aftertreatment system
Technology Applicability
Applicable to all diesel technology applications but with more relevance on
applications with larger engines and large aftertreatment systems with greater
thermal inertia
Highway benefits - Minimal benefit and only soon after starting when
aftertreatment is cold
City benefits - Benefit most noticeable for real world situations when vehicle is
used frequently for short journeys from cold or cool start when aftertreatment is
below effective operating temperature
Pre-turbine catalyst allows for less aggressive heating strategies to keep
aftertreatment in correct operating temperature window
Component durability must be considered in placing catalyst closer to engine and
may require metallic catalyst substrate
(worst)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
10
(best)
Picture: www.emitec.com
CG001019
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30 Seotember 2011
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Technology Assessment- Diesel Engines
Electric Turbo-Compounding
RICARDO
Technology and Status
Ratings of Technology
Concept: Electric turbo-compounding device recovers waste exhaust energy
and converts this to electrical energy
Base Functioning: Exhaust energy that would otherwise be wasted is used to
drive a turbine coupled to an electrical generator to generate electrical power.
The electrical power can be stored in conjunction with hybridization or fed back
as shaft power directly to reduce fuel demand on engine
CO2 Benefit: 4-5% improvement in fuel efficiency depending on cycle
Costs: Technology is proven on heavy duty applications but specific
development would be required for lighter duty matching and application.
Incremental variable cost for ETC and power electronics.
Technology Applicability
Already applied to heavy duty applications - more applicable to heavier
applications
• Highway benefits - significant benefit - up to 5% depending on duty cycle and
engine load on highway
• City benefits - transient low speed and load does not offer the same quality of
exhaust energy for energy recovery. There is potential for worsened fuel economy
due to increased back-pressure at some parts of operation
Idle-stop benefits would be acheived if coupled with hybridization
• More benefit would be obtained with electrification of accessories.
10
(worst) (best)
Effectiveness ^^H__(5>
Availability
Market
Penetration
Long-Term • A
Cost Viability
Current
Maturity
Current • A
V
Visualization
Picture: Source: John Deere, DEER 2006
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Technology Assessment- Diesel Engines
Calibration "System" Optimization for CO2
(Engine + Transmission + Aftertreatment)
RICARDO
Technology and Status
Ratings of Technology
Concept: Application of a sytem level technology selection to add increased
NOx aftertreatment allowing optimization of engine out emissions for lower C02
and higher NOx (and revised total gearing)
Base Functioning: Instead of minimizing engine out NOx for smaller NOx
aftertreatment a system approach for C02 could oversize NOx aftertreatment
and allow increased engine out NOx emissions with reduced engine out C02.
Combined with transmission ratio selection for C02 rather than NOx
CO2 Benefit: 2-4% offset by increased DEF utilization and partially offset by
increased fuel consumption during warm-up to light off aftertreatment
Costs: Aftertreatment cost would rise in line with additional reduction
capacity. DEF system would also need to be resized to account for additional
DEF consumption
Technology Applicability
Technology applicable to all areas of diesel application
• Highway benefits - lower C02 emission by reduced engine speed operation from
higher gearing and more optimal C02 calibration with increased engine out NOx
• City benefits - lower engine speed and improved transient C02 provide lower
speed and load benefits
• Idle-stop - stop start operation would need to be treated carefully to maintain
aftertreatment operating temperature
Increase DEF consumption woudl offset cost benefit to end-user and extend
payback duration
10
(worst) (best)
Effectiveness • (4)
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
Picture: Ricardo, Inc.
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Technology Assessment- Diesel Engines
Narrow Speed Range Operation
RICARDO
Technology and Status
Ratings of Technology
Concept: Powertrain designed to enable the engine to operate within a narrow
speed band range with full emissions and economy optimization in this range
Base Functioning: Powertrain coupled to hybrid systems and/or highly flexible
transmissions allowing engine to be optimized for narrow speed band for best
emissions and economy. Contrast to traditional optimization that considers
entire speed load range requirements with many compromises
CO2 Benefit: 2-4% from optimization of combustion plus more opportunity by
limiting higher engine speed for friction reduction with design factors for narrow
speed range envelope
Costs: Little impact to cost if highly flexible transmissions and/or hybrid already
selected. Reduced engine optimization development offset by increased
powertrain system development
Technology Applicability
• Applicable to all classes of vehicles using hybrid systems or high numbers of gear ratios
that allow engine speed range to be very narrow
Highway benefits - Improved economy by maintaining engine in high efficiency island.
Enhanced benefit if emission spikes in transient operation can be avoided allowing
further optimization for fuel economy
• City benefits - As highway plus ability to set speed and load on engine for rapid
aftertreatment warm-up. Engine speed set point can be matched to provide optimal
electrical energy generation efficiency for recharging hybrid energy reserve enhancing
idle and stop benefits
• Constant speed operation may prove un-desirable noise characteristic compared to
traditional powertrain solutions
(worst)
. 10
(best)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
Engine Speed (RPM)
Picture: Ricardo Inc.
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Technology Assessment- Diesel Engines
System Integration at Engine Level
RICARDO
Technology and Status
Ratings of Technology
Concept: Combine components to reduce mass and thermal inertia giving
improved package and faster warm-up. Electrify ancillaries to eliminate FEAD
and allow variable performance independent of engine speed
Base Functioning: Combination of components (e.g. exhaust manifold and
cylinder head) to improve response time for turbocharging and aftertreatment
warm-up. Electrification of FEAD reduces parasitic losses and allows operation
to be optimized to most efficient condition for operating point (e.g electrical
coolant pump, oil pump or AC compressor)
CO2 Benefit: 1-2%
Costs: Added variable costs for more complex production offset by reduced
material. Electrification in conjunction with hybridization.
Technology Applicability
• Technology is applicable to all diesel technology sectors
Highway benefits - reduced frictional losses at higher speed and load points by
designing and running ancillaries at optimal conditions
• City benefits - Rapid aftertreatment warm-up reduces fuel consumption in warm-
up phase and allows earlier transition to warm fuel efficient maps. Ability to run
ancillaries faster at lower engine speeds will enable lower power loss and should
enable component downsizing
10
(worst)
(best)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
Picture: Ricardo, Inc.
CG001019
Prepared for SRA and EPA
30 Seotember 2011
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Technology Assessment- Diesel Engines
Diesel Engine Technology Applicability
RICARDO
Please note that the applicability of hybrid powertrains is covered in a separate
Vehicle
Classification
Small Car (Ford Focus)
Standard Car (Toyota Camry)
Small MPV (Saturn Vue)
Full-sized Car (Chrysler 300C)
Large MPV (Dodge Grand Caravan)
Truck (Ford F1 50)
Heavy light-duty truck (Ford F250/F350)
0
Q.
^
0
O
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0
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0
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CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Outline
RICARDO
Introduction
Spark ignited engine technologies
Diesel engine technologies
Hybrid vehicle technologies
Transmission technologies
Vehicle technologies
Conclusions
CG001019
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30 Seotember 2011
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Technology Assessment- Hybridized Powertrains
Hybrid Functionality Matrix
Hybrid technology's primary purpose is to enable vehicle functionally that offers fuel efficiency.
RICARDO
None
Conventional
Micro
Belt
starter /
generator
Micro
Belt
mounted
parallel
Mild
Crank
mounted
parallel
/||\fl A \
Full
P2 parallel
hybrid
Full
Input
Powersplit
Full
Compound
powersplit
Full
2-mode
powersplit
Full
Series
hybrid -
Electrical
Full
Series
hybrid -
Hydraulic
Engine idle off
Launch assist
Regeneration
Electrical only
mobility
CVT
No
No
No
No
No
Yes
No
No
NO
No
Yes
Small
amount
Small
amount
No
No
Yes
Some
Some
No
No
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
Power Steering
Air conditioning
Brakes
Belt
Belt
Standard
Electrical
Belt
Standard
Electrical
Belt
Standard
Electrical
Belt
Standard or
blended
Electrical
Belt or
electrical
Blended
Electrical
Belt or
electrical
Blended
Electrical
Belt or
electrical
Blended
Electrical
Belt or
electrical
Blended
Electrical
Belt or
electrical
Blended
Electrical
Belt or
electrical
Blended
ICity Driving
Highway Driving
0
0
+
0
++
0
++
+
+++
+
++++
+
++++
+
++++
+
++++
-
++++ 1
- 1
CG001019
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Technology Assessment- Hybridized Powertrains
Hybrid Technology Area Considerations
RICARDO
Hybrid technology largely available now but needs cost reduction efforts to provide
financial justification to consumers; largely expected to come through volume increases
(economy of scale) & commodity mindset
Pace of development
Change in fuel prices (or fuel tax legislation) could dramatically accelerate (or slow)
hybrid development and implementation. CAFE requirements will drive technology
development in near term.
Li-ion battery development largely in flux as well, but not necessarily an impact to
hybrid development, as NiMH is sufficient (i.e., Li-ion required for EV and PHEV but not
current strong hybrid technology)
Many hybrid applications today being consumed by early (technology) adopters and/or
those focused on environmental impact and energy independence
Hybridization still difficult to justify based purely on financial business case
Governmental legislation (e.g., CAFE or CO2 requirements) largely responsible for
hybrid investment
Benefits of hybrid technologies are generally independent of component technologies
(Electrical machine & energy storage) due to good round trip efficiency attributes of current
technologies.
Some small correlation exists, and with parameterization in model, opportunity to
sweep parameters to evaluation sensitivity.
CG001019
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Technology Assessment- Hybridized Powertrains
Micro Hybrid: Stop-Start
RICARDO
Technology Description and Status
Ratings of Technology
Concept: Most basic of hybridization, allows for simple engine shut-off during
idle periods; typically employs enhanced starter motor and limited use of driver
comfort features during engine off (e.g. Radio, some heat, but no A/C)
Base Functioning: Decreases wasted fuel by minimzing idling but provides no
benefit for highway use or when air conditioning is required/desired
CO2 Benefit: 3-5% over city cycles. 0% over highway
Costs: This is the lowest cost hybrid system and can be implemented relatively
quickly on most vehicles on the market today. Stop-start systems are
somewhat mature and readily available off the shelf. Further development will
yield increased user acceptance (e.g. Transparent integration with little to no
detriment to existing vehicles in terms of NVH, acceleration, etc.)
Technology Applicability
Stop-start technology can be applied to almost all vehicles including passenger
cars, medium and heavy duty trucks and even off-highway or agricultural
vehicles.
• Benefits are limited, though, to vehicle applications that have some periods of
idling. For example, long-haul trucks with extended highway operation will see
little to no benefit. Similiarly, as air conditioning is not available during engine-off
periods, users may experience some degradation in performance that could be
unacceptable.
10
(worst)
(best)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
CG001019
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Technology Assessment- Hybridized Powertrains
Mild Hybrid: Integrated Belt Starter-Generator (IBSG)
RICARDO
Technology Description and Status
Ratings of Technology
Concept: The alternator is replaced with a new electric machine that can
provide lauch assist as well as replacing the electrical supply of the alternator
during normal vehicle operation. Typically this machine can also be used for
energy recapture during braking..
Base Functioning: Provides stop-start functionality (see "Stop-Start" slide) as
well as electric launch assist, which, when coupled to a dedicated energy
storage system with a charge sustaining strategy, can decrease fuel
consumption during acceleration from a stop.
CO2 Benefit: 3-7% over city cycles, ~0% over highway cycles
Costs: Several IBSG systems are on the market today so development costs
are largely sunk. Purchase costs of the system are now decreasing as volume
grows such that financial payback may be viable soon.
Technology Applicability
IBSG systems can be applied to a wide variety of applications including
passenger cars and medium and heavy duty trucks with benefits seen in city
cycles. Due to the small size of the IBSG, relatively limtied ability to downsize,
but some bennefit.
Visualization
In lire 6 cylinder OQHC
10
(worst) (best)
Effectiveness ^H <5)
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
CG001019
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Technology Assessment- Hybridized Powertrains
Mild Hybrid: Integrated Crank Starter-Generator (ICSG)
[also known as Integrated Motor Assist (IMA)]
RICARDO
Technology Description and Status
Ratings of Technology
Concept: An e-machine is added to or replaces the flywheel. Larger than the
e-machine used in an ISBG, the motor can provide lauch assist and
regenerative braking as well additional power during a variety of vehicle
operating modes and, thus, is applied in conjunction with a downsized engine.
Base Functioning: Provides stop-start functionality and launch assist. This
provides the opportunity to use of a smaller engine to increase efficiency
throughout the operating range of the vehicle, not just during launch from a
stop.
CO2 Benefit: 16-20% on city cycles, ~0% on highway cycles
Costs: ICSG systems are on the market today so development costs are
largely sunk. Purchase costs of the system are now decreasing as volume
grows and the greater fuel efficiency is great enough to provide reasonable
financial payback today.
Technology Applicability
ICSG systems can be applied to a wide variety of applications including
passenger cars and medium and heavy duty trucks with benefits mostly seen in
city drive cycles. The reduced engine sizes enabled by the hybrid system provide
highway bennefits.
Typically, these systems have been used with a CVT to avoid Torque converter
losses.
10
(worst)
(best)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
CG001019
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Technology Assessment- Hybridized Powertrains
Full Hybrid: P2 parallel Hybrid
Technology and Status
Concept: An e-machine is inserted between the engine and the transmission,
typically with a clutch between the engine and e-machine. Larger than the e-
machine used in an ISBG, the motor can provide lauch assist and regenerative
braking as well additional power during a variety of vehicle operating modes
and, thus, is applied in conjunction with a downsized engine.
Base Functioning: Provides stop-start, electrical launch, and launch assit. This
optimizes the use of a smaller engine to increase efficiency throughout the
operating range of the vehicle, not just during launch from a stop.
CO2 Benefit: 18-22% on city cycles, ~0% on highway cycles (downsizing
offers bennefits)
Costs: No P2 parallel hybrids are in production today, so development costs
will still need to be invested, however parts bin exists today. The cost of the
system is higher thana ICSG, however, the system has only 1 electrical machine
so its costs should be lower than more advanced hybrids
Technology Applicability
P2 hybrids can be applied to a wide variety of applications including passenger
cars and medium and heavy duty trucks with benefits seen mostly in city drive
cycles. The reduced engine sizes enabled by the hybrid system provide highway
bennefits.
System can be used with an AT, however, To maintain efficiency, a CVT or DCT
should be used to avoid Torque converter losses.
RICARDO
Ratings of Technology
(worst)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
Wheels
Clutch
Transmission
CG001019
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Technology Assessment- Hybridized Powertrains
Full Hybrid: Input Power Split Hybrid
RICARDO
Technology Description and Status
Ratings of Technology
Concept: Power split hybrids use an electric machine directly integrated into
the transmission, and either provide an additional input parallel to the engine or
act as an additional output from the transmission. Both varieties permit an
electric (only) operating mode.
Base Functioning: Power split encompasses all of the aforementioned
technology providing stop-start, launch, and engine downsizing benefits in plus
the ability to provide an electric-only operating mode, when used in conjunction
with the appropriate electric accessories.
CO2 Benefit: 22-33% in city driving, some bennefit in highway driving
Costs: Development is ongoing with room for both performance improvement
and cost reduction but initial systems are now widely spread in the market place
(e.g. Ford Fusion and Escape and Toyota Prius).
Technology Applicability
• As a full or strong hybrid, the power split hybrid offers very good benefit of
hybridization
• Challenge with cost due to two electrical machine solution.
• Fuel efficiency improvement is found across the range and in all operating cycles
since engine downsizing and electric accessories optimize performance and
efficiency of the combustion engine and the vehicle as a whole
(worst)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
Gene-ator
1C Engine
Sun 3 = 3
Piarwtary Gears
Annul us
Electric
Motor
Whesls
CG001019
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Technology Assessment- Hybridized Powertrains
Full Hybrid: Two-Mode Power Split
RICARDO
Technology Description and Status
Ratings of Technology
Concept: Two-Mode hybrids use electric machines (usually two) directly
integrated into the transmission for maximum operating flexibility with operation
as input powersplit or compound power split gearing configuration via clutch
actuation.
Base Functioning: Two-Mode encompasses all of the aforementioned
technology providing stop-start, launch, and enables engine downsizing benefits
in plus the ability to provide an electric-only operating mode, when used in
conjunction with the appropriate electric accessories.
CO2 Benefit: 22-33% in city drive cycle. Some bennefit in highway driving
Costs: Development is ongoing as Two-Mode hardware is still very expensive,
providing little commercial payback to the customer currently. However, Two-
Mode systems are proliferating in the market place with GM offering truck and
SUV variants now, and BMW, Mercedes and Chrysler products coming soon).
Technology Applicability
As a full or strong hybrid, the Two-Mode hybrid offers maximum benefit of
hybridization but is also the most costly and complex of all architectures to
implement.
Fuel efficiency improvement is found across the range and in all operating cycles
since engine downsizing and electric accessories optimize performance and
efficiency of the combustion engine and the vehicle as a whole
(worst)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
Steady Stite ENfcfencv
Vihicte Spnd |mph]
CG001019
Prepared for SRA and EPA
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Technology Assessment- Hybridized Powertrains
Full Hybrid: Series Electrical
RICARDO
Technology and Status
Ratings of Technology
Concept: Series electrical hybrid systems include two electrical machines and
a battery. One EM is located on drvie axle and is sized for peak loads, and
second EM is located on engine and is sized for average loads.
Base Functioning: Energy storage system enables load averageing and
engine off operation. As driveline and engine are decoupled, engine can be
single point engine or operate on best-efficiency line engine.
CO2 Benefit: 22-33% in city drive cycle. Potenally reduced in highway
driving, depending on degree of reduced engine size enabled.
Costs: The cost implications of two electrical machines (one large and one
small) and a battery have limited the appeal of this technology to the industry.
Technology Applicability
Series hybrids are not currently in production, and technology approach has not
been embraced by industry (has been championed in research community) due
to the costs associated with multiple large electrical machine size & a battery.
With introduction of EVs, opportuntity for industry to gain comfert with series
electrical and increase volumes to reduce costs.
10
(worst)
(best)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
CG001019
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30 Seotember 2011
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Technology Assessment- Hybridized Powertrains
Full Hybrid: Series Hydraulic
RICARDO
Technology Description and Status
Concept: Hydraulic accumulators are used to aid in deceleration, then the
stored energy is released back into the vehicle for launch assist using hydraulic
pumps connected to an axle or transmission.
Base Functioning: Kinetic energy that would otherwise be translated to heat in
the braking system is recaptured for later use. Can also be used for engine
downsizing.
CO2 Benefit: 22-33% in city drive cycle. Potenally reduced in highway
driving, depending on degree of reduced engine size enabled.
Costs: Hydraulic hybridization is still in early development with only a few
demonstration vehicles on the road today. Application of hydraulic hybridization
is much less costly in vehicles that already employ extensive hydraulic systems
for specific vocations (e.g., garbage compactor) and increased efficiency is
limited to vocations with extreme stop-start cycles and agressive deceleration.
Technology Applicability
• Hydraulic hybrid systems typically suggested in niche applications such as refuse
trucks, where large power required for regeneration is well suited to hydraulic
systems.
• Potentially reduced fuel economy in highway driving, depending on degree of
reduced engine size enabled.
Hydraulic hybrid technology development has been significantly slower than
electrical hybrid technology development rate, and use of hydraulic driveline is
not consistent with other high profile technology initiatives such as EVs, PHEVs
and vehicle electrification.
Ratings of Technology
10
(worst)
(best)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
• .-i-.i i- High Tr-. i-r
Hvdmub? Eit*rgv Sle*og* A
Socoraf Mydiouhc
fi.rnp. Male,
CG001019
Prepared for SRA and EPA
30 Seotember 2011
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-------
Outline
RICARDO
Introduction
Spark ignited engine technologies
Diesel engine technologies
Hybrid vehicle technologies
Transmission technologies
Vehicle technologies
Conclusions
CG001019
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30 Seotember 2011
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Technology Assessment - Transmissions
Technology Area Overview
RICARDO
For this technology area, we have the following thoughts for the situation for in
2020-2025:
North American market will continue to be dominated by automatic transmissions for 1C engines with emphasis on
increasing launch device efficiency and smart kinematics design
Higher presence of more fuel efficient AMT's and DCT's expected
Increase in simplified single/two speed gearboxes for hybrid applications
CVT development expected to be on the decline in the North American market (although still being pursued by
Japanese market)
Pace of development
Development of AMI and DCT technology expected to be implemented from European and Japanese efforts
Detroit 3 actively pursuing DCT technology, with teaming arrangements established between OEMs and Tier 1 to
develop technologies
Improvements for automatic transmissions are on-going with new technologies being implemented into luxury
vehicles and then cascaded down to other vehicle classes.
Single/two speed gearboxes for hybrid applications require minimal investment and lead time
Comparison to baseline
Given 94% of North American transmissions are automatic, improvements in efficiency (resulting in C02
improvements) will be realized through:
Smart kinematics design (2-5%)
Component efficiency improvement or alternative technologies (3%)
Launch devices (2-6%)
Dry sump technology (2%)
Estimates of improvement depend on the drive cycle, are not simply additive, and are subject to quality of baseline
CG001019
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Technology Assessment - Transmissions
Transmission Summary
Automatic (with Torque Converter)
Hydraulically operated, using a fluid coupling or
torque converter and a set of gearsets to provide
a range of gear ratios
Decrease in efficiency associated with viscous
losses from torque converter
| CVT (Continuous Variable Transmission)
Rather than using gears, the CVTs in
currently available vehicles utilize a
pair of variable-diameter pulleys
connected by a belt or chain that can
produce an infinite number of
engine/wheel speed ratios.
Reliability and efficiency issues
prevent this technology from
roadmap development
RICARDO
AMT (Automatic Manual Transmission)
AMI operates similarly to a manual transmission
except that it does not require clutch actuation or
shifting by the driver.
Automatic shifting is controlled electronically
(shift-by-wire) and performed by a hydraulic
system or electric motor.
Poor shift quality has excluded this technology
from the study
DCT (Dual Clutch Transmission)
Uses two separate clutches
for even and odd gear sets
Eliminates the use of a
torque converter and utilizes
either wet or dry type launch
clutches
CG001019
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Technology Assessment - Transmissions
Technology Area Summary
Launch Devices
- Wet Clutch
Damp Clutch
- Dry Clutch
Multi-damper Torque converter
Magnetic clutch
Shifting Clutch Technology
Smart Kinematic Design
Dry Sump
Efficient Components
Super Finishing
Lubrication
CG001019
Prepared for SRA and EPA
RICARDO
30 Seotember 2011
RD.11/342305.1
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Technology Assessment - Transmissions
Launch Device: Wet Clutch
RICARDO
Technology and Status
Concept: provides torque transmission during operation by means of friction
action between surfaces wetted by a lubricant
Base Functioning: Increases fuel effieciency by reducing hydraulic parasitic
losses over a conventional torque converter when it is slipping.
CO2 Benefit: Benefit realized at launch and during transient driving
Costs: up to 20% less than a conventional torque converter
Technology Applicability
Ratings of Technology
(worst)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
• Technology applicable to planetary, parallel-axis, AMT and dual clutch
transmissions
• Requires special lubrication system or lubricant to satisfy gearbox lubrication
requirements and actuation requirements.
• Parasitic losses of lubrication system diminish overall benefit over torque
converter.
• Improvement in city driving, little for highway
"Note: Effectiveness relates to improvement in transmission efficiency
10
best)
Picture: www.cerom.lsu.edu
CG001019
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Technology Assessment - Transmissions
Launch Device: Damp Clutch
RICARDO
Technology and Status
Concept: Similar concept as a wet clutch but only a limited spray is applied to
achieve cooling
Base Functioning: Still requires a lubrication system but is more efficient due
to controlled environment (less windage and churning)
CO2 Benefit: Similar benefits as a dry clutch
Costs: ~$25 above wet clutch
Technology Applicability
• Applicable to most automatic transmissions - best of both worlds, efficiency of a
dry clutch matched with the longevity and higher torque capacity of a wet clutch
As for the other launch devices, the increase in efficiency is applicable mostly to
city driving.
"Note: Effectiveness relates to improvement in transmission efficiency
Ratings of Technology
(worst)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Maturity
Visualization
Picture: www.cerom.lsu.edu
CG001019
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30 Seotember 2011
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Technology Assessment - Transmissions
Launch Device: Dry Clutch Advancements
RICARDO
Technology and Status
Ratings of Technology
Concept: Standard manual clutch require advanced materials to provide heat
dissipation to be used in automatic applications or electric assist (on/off) to
prevent slipping
Base Functioning: Thermal load resulting from engagement prevent dry
clutches from being used in high torque and heavy duty cycle applications but
are more effiecient since they don't require an additional lubrication system and
significatntly reduce parasitic shear fluid losses.
CO2 Benefit: Benefit realized at launch and during transient driving
Costs: Dry Clutch materials +10-20%, Electric motor $1500
1 ^ ^10
(worst)
Effectiveness |
Availability |
Market i —TV-
Penetration ' \r
i_ony- 1 ern
current , /\
Matnritv • \/
(best)
wl
T6T]
•
A
<^ •
V
1
Technology Applicability
• Advancements in material or electric assist could enable this technology to be
used in larger vehicles and more severe duty cycles
City driving improvement
"Note: Effectiveness relates to improvement in transmission efficiency
Visualization
Ihrust pad
drive1
plale
disengaged (pedal pressed down)
svei
engaged (pedal up)
Picture: www.cerom.lsu.edu
CG001019
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Technology Assessment - Transmissions
Launch Device: Multi-Damper Torque Converter
RICARDO
Technology and Status
Ratings of Technology
Concept: Dampers in torque converter enable lower lock-up speed
Base Functioning: The more fuel-intensive period of hydrodynamic power
transfer is shorter
CO2 Benefit: Increase in efficiency from reduced slippage and smoother
shifting
Costs: Increase
Technology Applicability
Multi-damper systems provide earlier much early TC clutch engagement,
however, drivability and limitied ratio coverage have limited the deployment of this
technology.
• Technology is best suited for deployment in 6 speed tranmssions and required to
be integrated during transmission design.
Technology provides improved efficiency for automatic transmissions at an
increase in cost.
"Note: Effectiveness relates to improvement in transmission efficiency
10
(worst) (best)
Effectiveness • (5)
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
Picture: www.zf.com
CG001019
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Technology Assessment - Transmissions
Launch Device: Magnetic Clutch
RICARDO
Technology and Status
Ratings of Technology
Concept: Using magnetic force to engage the clutch
Base Functioning: Non contact engagement launch device to prevent frictional
losses
CO2 Benefit: Benefit realized at launch and during transient driving
• Costs: Cost impact unclear due to technology in early stage of development
Technology Applicability
Technology is still under early development and it use will be constrained by
limited torque transfer capabilities, uncertian reliability, and significant engineering
development to mature.
Offers opportuinty to remove hydraulic sub-system compoenets and associated
losses. Technology requires current draw to operate, thus idealy suited for highly
electrified vehicles.
Technology best suited to low torque applications with miniminal refinement
vehicles and technology will need to be integrated in clean sheet transmissions
with large ratio coverage.
"Note: Effectiveness relates to improvement in transmission efficiency
(worst)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
PART NO.
3
4
, ' !
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10
CADI .1
/ft IN BRACL SLDASM
CLUTCH MAGNET-SLDPfiT
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on
1
1
SCALE: 1:1
ARDEN ROSENBLATT
Picture: www.uweb.ucsb.edu
CG001019
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Technology Assessment - Transmissions
Shifting Clutch Technology
RICARDO
Technology and Status
Concept: Utilizing high thermal capacity technolgoy to reduce plate count and
lower clutch losses during shifting
Base Functioning: Reduced number of plates for shifting process and reduced
hydraulic cooling requirements result in increased overall transmission
efficiency for similiar drivability.
CO2 Benefit: Through all driving conditions potentially including idle
Costs: similar to AMI cost
Technology Applicability
Technology deployment required during transmission design phase and has been
limited by industry prioritization to drivability over shift efficiency.
• Technology will be best suited to smaller vehicle segments due to reduced
drivability expectations - there will be a struggle to develop this technology for
higher torque applications
"Note: Effectiveness relates to improvement in transmission efficiency
Ratings of Technology
10
(worst)
(best)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
Picture: www.cerom.lsu.edu
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Technology Assessment - Transmissions
Smart Kinematic Design
RICARDO
Technology and Status
Concept: Using analysis to design for efficiency by selecting the kinematic
relationships to optimize the part operational speeds and torques for efficiency
Base Functioning: Large improvements in efficiency have been noted for
clean sheet designs for 6-speed and 8-speed transissions
CO2 Benefit: Increase in efficiency reduces fuel consumption
Costs: Low cost - analysis part of design phase
Technology Applicability
All applications and vehicle classes benefit from this design approach
Benefits are realized in city and highway driving
Note: Effectiveness relates to improvement in transmission efficiency
Ratings of Technology
(worst)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
Picture: www.adr3.co.uk
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Technology Assessment - Transmissions
Dry Sump
RICARDO
Technology and Status
Concept: Dry sump lubrication systerm keeps the rotating members out of oil
Base Functioning: Reduces losses due to windage and churning
CO2 Benefit: Fuel efficiency increases with transmission efficiency
• Costs: Adds cost (~$50/pc) but as technology matures cost will go down
Technology Applicability
• All applications and vehicle classes benefit from this lubrication design
Most benefit achieved at higher speeds
"Note: Effectiveness relates to improvement in transmission efficiency
Ratings of Technology
10
(worst)
Effectiveness • <4
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
(best)
Visualization
Picture: www.cerom.lsu.edu
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Technology Assessment - Transmissions
Efficient Components
RICARDO
Technology and Status
Concept: Continous improvement in seals, bearings and clutches all aimed at
reducing drag in the system
Base Functioning: A reduction in drag with out a reduction in performance
increases the efficiency of the transmission
CO2 Benefit: Fuel efficiency increases with transmission efficiency
Costs: New materials, designs are expensive when they hit market (20%)
Technology Applicability
• All applications and vehicle classes benefit from this lubrication design
• City and highway driving fuel effieciency improvements
"Note: Effectiveness relates to improvement in transmission efficiency
Ratings of Technology
10
(worst) (best)
Effectiveness ^H <5]
Availability
Market
Penetration
• 0
Long-Term • r-A-
Cost Viability
Current
Maturity
Visualization
Picture: www.cerom.lsu.edu
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Technology Assessment - Transmissions
Super Finishing
RICARDO
Technology and Status
Concept: Chemically treating internal gearbox parts for improved surface finish
Base Functioning: Improved surface finish reduces drag which increases
efficiency
CO2 Benefit: Fuel efficiency increases with transmission efficiency
• Costs: Currently ~$0.50/part
Technology Applicability
• All applications and vehicle classes benefit from this lubrication design
• City and highway driving fuel effieciency improvements
"Note: Effectiveness relates to improvement in transmission efficiency
Ratings of Technology
10
(worst) (best)
Effectiveness • <5)
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
Ra: 0.025 (jm
Rz: O.I7 urn
Picture: www.geartechnology.com
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Technology Assessment - Transmissions
Lubrication
RICARDO
Technology and Status
Technology Applicability
• All applications and vehicle classes benefit from improved lubrications
• City and highway driving fuel effieciency improvements
Ratings of Technology
Concept: Development in the area of lubrication properties is ongoing
Base Functioning: New developments in reducing oil viscosity while
maintaining temperature requirements will have a positive effect on
transmission efficiency
CO2 Benefit: Benefit across all vehicle classes and operating conditions
Costs: TBD
1 ^ ^10
(worst)
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Penetration '
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Cost Viability '
Current i
Maturity *
(best)
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"Note: Effectiveness relates to improvement in transmission efficiency
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Technology Assessment - Transmissions
Transmission Technology Applicability
RICARDO
Launch Technology
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System
Automatic with Torque Converter
Automatic Manual Transmission
Dual Clutch
CVT
X
X
X
X
X
?
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Vehicle
Classification
Small Car (Ford Focus)
Standard Car (Toyota Camry)
Small MPV (Saturn Vue)
Full-sized car (Chrysler 300C)
Large MPV (Dodge Grand Caravan)
Truck (Ford F1 50)
Heavy light-duty truck (Ford F250/F350)
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
?
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Outline
RICARDO
Introduction
Spark ignited engine technologies
Diesel engine technologies
Hybrid vehicle technologies
Transmission technologies
Vehicle technologies
Conclusions
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Technology Assessment - Vehicle
Vehicle Summary (1 of 3)
RICARDO
Mass Reduction: Material Substitution
For a given set of performance targets, a heavy
vehicle will require more power, thus consume
more energy. Reductions in weight can occur
through material substitution (e.g., steel to
aluminum).
Aerodynamics: Passive
Vehicle Aerodynamics; have a greater influence
on drive-cycles with a higher average speed.
Dependant compromises chosen, significant
opportunity is available in shape development
(passive aero).
Mass Reduction: Component Optimization
Dependant on the compromises (e.g., for
manufacturing flexibility, passenger volume etc),
reductions in weight can also occur through
component optimization.
Aerodynamics: Active
Gains from active aero through controlled cooling
apertures, vehicle ride height control etc are also
possible.
CG001019
Prepared for SRA and EPA
30 September 2011
RD.11/342305.1
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Technology Assessment - Vehicle
Vehicle Summary (2 of 3)
RICARDO
Thermo-Electric Generators
Thermo-Electric Generation (TEG); use the heat
in exhaust gas (waste energy) to generate
electricity using the Seebeck effect. This can be
used to drive ancillaries etc, reducing the power
requirement of the engine.
Tire Rolling Resistance
On-going investment in research by the tire
companies is reducing the energy necessary to
drive a vehicle forwards.
HVAC System Load Reduction
Reduced heat loading; by insulating the body of
the vehicle, using alternative technologies for the
glazing and ventilation systems, it is possible to
significantly reduce the energy requirements of
the HVAC systems.
Intelligent Cooling Systems
Improved engine thermal control using an electric
coolant pump, electric fans and electric 3-way
valve.
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Technology Assessment - Vehicle
Vehicle Summary (3 of 3)
RICARDO
Electric Power Assisted Steering
Replaces FEAD-driven hydraulic steering
assistance with electric motor. Increasingly
prevalent in small and medium passenger cars
(particularly in Europe).
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Technology Assessment - Vehicle
Mass Reduction: Substitution
RICARDO
Technology and Status
Concept: Replacement of current material with HSS/AHSS/AI/Mg/CF* etc.
Base Functioning: Fuel economy improvements are through a reduction in the
rolling resistance losses, i.e., the frictional force is reduced by reducing the
normal force (weight) of the vehicle. A secondary effect is that a lighter vehicle
with lower inertia can use a smaller powertrain to accelerate that reduced mass.
C02 Benefit: A 10% vehicle mass reduction can deliver a 2.7-4.1 % fuel
economy improvement with constant engine size, but a 4.7-6.7% improvement
when the engine is downsized to maintain constant performance.
Costs: Dependant on material selected and price reductions with increasing
volume supply.
Technology Applicability
• Direct benefit, in growing market use, in all market sectors, and all powertrain
variations.
Enables engine down-sizing.
• Lowers inertia.
* HSS=High Strength Steel, AHSS=Advanced High Strength Steel, AI=Aluminum, MG=Magnesium,
CF=Carbon Fiber
Ratings of Technology
1
(worst)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
(best)
Aluminum-bodied Jaguar XJ
Prepared for SRA and EPA
30 Seotember 2011
Picture: www.automotive.com
RD.11/342305.1
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Technology Assessment - Vehicle
Mass Reduction: Optimization
RICARDO
Technology and Status
Ratings of Technology
Concept: Optimization of vehicle, vehicle systems and components for weight,
not style, manufacturing flexibility or passenger volume. Examples; 30% wheel
mass-saving, change from body-on-frame to unibody for trucks.
Base Functioning: Fuel economy improvements are through a reduction in the
rolling resistance losses, i.e. the frictional force is reduced by reducing the
normal force, (weight) of the vehicle. A secondary effect is due to a lighter
vehicle with lower inertia can use a smaller powertrain to accelerate that
reduced mass.
C02 Benefit: 10% mass reduction can improve fuel economy by 6.7%.
Costs: Can be a cost REDUCTION; optimizing an aluminum wheel with a
30% reduction in weight can give a cost SAVING of 25^0%.
Technology Applicability
Has the potential to be applied to many areas of a vehicle. Direct benefit, in
growing market use, in all market sectors, and all powertrain variations.
Enables engine down-sizing.
• Lowers inertia.
• Additional significant opportunity exists with vehicle size. Passenger vehicles
have grown SIGNIFICANTLY in the past 3 decades. The manufacturers say that
this is due to meet 'market requirements'. If vehicles can be forced to become
smaller with each successive iteration, rather than bigger, this equates to lighter.
This has the additional benefit of smaller frontal area, thus (aero details remaining
constant), the CdA reduces, thus the energy to drive the vehicle through the air is
reduced.
1
(worst)
> 10
(best)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
Saves 2.5 kg/wheel
(24%)
Picture: various sources
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Technology Assessment - Vehicle
Aerodynamics: Passive
RICARDO
Technology and Status
Ratings of Technology
Concept: Substantial opportunity still exists to lower the coefficient of drag (CD)
through body shape development, smoothing under-floors, faring-in wheels etc.
Base Functioning: A reduction in CD has a direct affect on reduction of the
force required to enable forward motion. As drag force is dependant on the
square of vehicle speed, at higher speeds, the fuel economy gain is increased.
C02 Benefit: A10% reduction in drag can give a 2.5% improvement in fuel
economy.
Costs: For most items, such as under-floor shields, wheel farings etc, there is
some associated on-cost, some items would be low cost or free, such as body
shape, and some, such as narrower tires, should be a cost reduction.
Technology Applicability
• The faster the vehicle travels, the greater benefit this is. Most effective where
significant freeway travel is required. Suits all powertrain variations.
Dependant on methods chosen, may have some weight penalty, thus city-only
vehicles may be penalized.
• Additional significant opportunity exists with vehicle size. Passenger vehicles
have grown SIGNIFICANTLY in the past 3 decades. The manufacturers say that
this is due to meet "market requirements". Safety not withstanding, if vehicles
can be forced to become smaller with each successive iteration, rather than
bigger, frontal area, thus drag force, will reduce (for the same CD).
• Suggested possible targets; sedans CD=0.25, SUVs CD=0.30, minivans CD=0.29,
hatchbacks CD=0.28.
1
(worst)
10
(best)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
Aptera
Picture: www.green.autoblog.com
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Technology Assessment - Vehicle
Aerodynamics: Active
RICARDO
Technology and Status
Ratings of Technology
Concept: Opportunity exists to reduce overall vehicle drag through improved
control of drag-affecting features (cooling apertures, ride-height etc). Radiator
grill sizing is designed for maximum thermal rejection; at high ambients / high
vehicle loads. Most of the time, the majority of vehicles need much less
cooling. Thus openings can be significantly reduced, reducing vehicle drag.
Base Functioning: A reduction in CD has a direct affect on reduction of the
force required to enable forward motion. As drag force is dependant on the
square of vehicle speed, at higher speeds, the fuel economy gain is increased
C02 Benefit: Active cooling aperture control could give an 8-10% vehicle drag
reduction. A 10% reduction in drag can give a 2.5% improvement in fuel
economy
Costs: Some associated on-cost
Technology Applicability
The faster the vehicle is required to travel, the greater benefit this is. Most
effective where significant freeway travel is required. Suits all powertrain
variations
Has some (small) weight penalty, thus city-only vehicles may be penalized;
however, city-only cars could have altered drive-cycles, as unlikely to need to
drive up mountains in Death Valley, at GVW
• Potential improvements through cooling system aperture control CD 0.008 for
small and medium cars and 0.03 for large passenger cars and SUVs
Where available, ride height reduction with increasing speed reduces the effective
frontal area, and increases tire coverage
1
(worst)
Effectiveness K2
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
(best)
Visualization
Picture: www.parkviewbmw.com
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
-------
Technology Assessment - Vehicle
Thermo-Electric Generators
RICARDO
Technology and Status
Ratings of Technology
Concept: Convert temperature differentials directly into electrical energy using
the Seebeck effect (temperature differential creates current/voltage same as in
thermocouples). A Thermo-Electric Generator (TEG) consists of hot side heat
exchanger(s), cold side heat exchanger(s), thermoelectric materials (type and
size depends on operating temperature) and compression assembly.
Base Functioning: 40% of energy from fuel is lost as exhaust heat. TEGs take
advantage of high engine exhaust gas temperatures (waste energy) to generate
electricity. This can be used to drive accessories or supplement power to an
electric motor.
C02 Benefit: Currently expected to give a 5% fuel economy improvement,
including the effects of the increased vehicle mass from the system (expected
to be in range of stop-start, brake regen, FEAD electrification).
Costs: Target cost $100/% FE improvement; currently more than this.
Technology Applicability
• Well suited to automotive application. Recovers some waste energy; which is up
to 40% of the energy from burning fuel.
• More effective at higher temperature differences, thus closer to the engine*, and
at high engine loads.
• Has some weight penalty, however the energy developed is expected to more
than offset this.
• Currently under development by BSST, Ford, BMW, Visteon and others. Material
development underway. Possible to be on production vehicles around 2015.
May give some packaging challenges
1
10
(worst) (best)
Effectiveness • (5)
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
CG001019
Prepared for SRA and EPA
30 Seotember 2011
Picture: www.customthermoelectric.com
RD.11/342305.1
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Technology Assessment - Vehicle
Reduced HVAC System Loading
RICARDO
Technology and Status
Ratings of Technology
Concept: Increasingly aerodynamic vehicles typically have larger front and rear
windows (for the same class of vehicle). This increases solar loading.
Improved thermal insulation reduces solar loading in the Summer and heat loss
in the Winter.
Base Functioning: Reduced thermal loading/heat loss reduces the energy
required by HVAC for cooling/heating. Insulated panels, GFPs*, double-glazing,
reflective films, active ventilation, reduced thermal mass are all possible
methods of realizing this. Optimization then enables smaller A/C components.
C02 Benefit: Suggest 8-10%, application dependant. May enable a doubling
of fuel economy. Recent introduction of SC03 drive cycle will clarify A/C effects.
Costs: Undefined, but expected to improve mpg (or range) for marketability.
Use of SC03 cycle may increase demand for reduced HVAC load.
Technology Applicability
Technology based on building applications and applies them to automotive use.
• VERY applicable to EVs, hybrids and high-mileage (mpg) vehicles, which are
most sensitive to accessory usage as a percentage of the overall vehicle load.
Increases mileage and range.
• The insulation on it's own has some weight penalty, however it allows reduction in
the sizing of the HVAC components, so potentially weight neutral.
Reduces degradation of interior panels due to thermal loading / IR attack; may
allow for cheaper materials (offsets the cost of the insulation application).
1
(worst)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
**Maturity
Visualization
(best)
*GFP=Gas Filled Panels
"Commercially available technology, to be optimized in vehicles
Picture: NREL Vehicle Ancillary Load Reduction Project Close-
Out Report
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
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Technology Assessment - Vehicle
Reduced Tire Rolling Resistance
RICARDO
Technology and Status
Ratings of Technology
Concept: Tire rolling resistance is driven by tread and carcass deformation and
relaxation as the tire rotates and moves into contact with the road and away.
Hysteresis in the tire from this deformation creates heat. Reducing the heat
generation reduces the rolling resistance.
Activity is underway to initiate rolling resistance information labeling for tires,
similar to that already shown for wear, traction and temperature performance.
Base Functioning: Fuel economy improvements are through a reduction in the
rolling resistance losses. Lower rolling resistance reduces the amount of energy
necessary to drive a vehicle forwards.
C02 Benefit: 10% rolling resistance reduction can improve fuel economy by
2-3%. Currently available tires can offer 10-20% resistance reduction over
conventional equipment. Further rolling resistance reductions of up to 50% are
predicted to be available in the next 10-15 years.
Costs: 10% rolling resistance approximates to $5 increase.
Technology Applicability
• Research into rolling resistance, and reducing compromises with traction and
wear are on-going.
Applicable to ALL vehicle types.
• On medium-duty trucks, changing from duallys to single-wides offer a further
benefit of a weight reduction, potentially allowing further improving fuel savings.
**Based on current technology, is moving forwards, in all vehicle markets. Further gains dependant on
further research by the tire companies
1
(worst)
> 10
(best)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
**Maturity
Visualization
Contribution of Tire Component!
to Rolling Resistance
35 - 50* Treid Compound
CG001019
Prepared for SRA and EPA
30 Seotember 2011
Picture: Bridgestone; Tires & Truck Fuel Economy Edition 4
RD.11/342305.1
-------
Technology Assessment - Vehicle
Intelligent Cooling Systems
RICARDO
Technology and Status
Ratings of Technology
Concept: Use an electric coolant pump to remove the FEAD load. By
removing it from FEAD also enables speed control, so rather than running at a
fixed speed related to engine speed, can be run at a speed suitable to the
current vehicle operating condition. Combines well with electric cooling fan and
improved flow routing control.
Base Functioning: Standard cooling systems are sized to provide cooling at
maximum load and ambient conditions. For majority of life of most vehicles, this
is not required. No FEAD load, more efficient operating point control. Enables
quicker warm up from cold. Reduces engine friction by enabling optimum
engine temperature operation, rather than over-cooling (on passive systems).
Further gains possible by controlled high temperature running, subject to
suitable NOx after-treatment systems being fitted (when necessary).
C02 Benefit: 3% fuel economy benefit on FTP cycle (assumes gain from
electric fan etc already taken).
Costs: Higher cost (possibly 5-6 times). Provides packaging flexibility as no
longer needs to be engine mounted.
Technology Applicability
Applicable to all vehicle types using 1C engines
Enables improved soak-condition control using the engine pump
1
(worst)
Effectiveness
Availability
Market
Penetration
Long-Term
Cost Viability
Current
Maturity
Visualization
(best)
engine speed i
pump speed nmax
pump speed n^, „
Picture: Pierburg Pump Technology 2008
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
-------
Technology Assessment - Vehicle
Electric Power Assisted Steering (EPAS)
RICARDO
Technology and Status
Ratings of Technology
Concept: Uses either rack or column-drive electric motors to assist driver
effort. Replaces engine-driven pump, hoses, reservoir, fluid and hydraulic rack.
Base Functioning: Removes load on FEAD for a system which isn't used for
much of the time (unless cornering or at slow speed).
C02 Benefit: On typical usage cycle, expect 2-3% improvement
Costs: Reduced warranty, reduced servicing. Cost competitive with hydraulic
systems. Enables integration with safety systems such as lane departure
warning, stability control (using "anti-skid" feedback) etc.
Technology Applicability
• Currently not available for truck weight-class vehicles. Ongoing developments in
this field are making this more likely for all vehicles in the 2020-2025 time-frame
• Required for vehicles with any EV functionality, to allow them to be steered in all
situations
Effectiveness
Availability
Market
Penetration
Long-Term
Viability
Current
Maturity
Visualization
Picture: www.trwauto.com
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
-------
Vehicle Technology Applicability
RICARDO
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Standard Car (Toyota Camry)
Small MPV (Saturn Vue)
Full-sized Car (Chrysler 300C)
Large MPV (Dodge Grand Caravan)
Truck (Ford F1 50)
Heavy light-duty truck (Ford F250/F350)
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CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
-------
Outline
RICARDO
Introduction
Spark ignited engine technologies
Diesel engine technologies
Hybrid vehicle technologies
Transmission technologies
Vehicle technologies
Conclusions
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
-------
Conclusions
RICARDO
A substantial list of technologies that could offer some benefit to GHG emissions
in the 2020-2025 timeframe was developed
These technologies were assessed by the Ricardo team
These assessments were reviewed with EPA
Advisory Committee provided input to assessments
Based on EPA feedback, the large list of potential technologies was reduced to
the set considered further in the study, "Computer Simulation of Light Duty
Vehicle Technologies for Greenhouse Gas Emission Reduction in the 2020-
2025 Timeframe"
These are described further in the main program report
(Ricardo reference RD. 10/157405.8)
CG001019
Prepared for SRA and EPA
30 Seotember 2011
RD.11/342305.1
------- |