Clean Automotive Technology,
Innovation that Works
&EPA
www.epa.sov/otaq/technolosy
World's First Full Hydraulic Hybrid SUV
Presented at 2004 SAE World Congress
a In collaboration with its partners, the U.S. Environmental Protection Agency (EPA) has been
researching advanced technology for the past ten years. EPA has had research partnerships with
several organizations including Ford Motor Company, Eaton Corporation, Army's National
Automotive Center and Parker Hannifin Corporation.
a Hydraulic hybrid technology is one of the EPA research
areas, with the vehicle presented at SAE being the
first-ever SUV with a fully hydraulic drivetrain.
a Hydraulic hybrids increase vehicle fuel economy in two
main ways: they allow the engine to be operated at
much more efficient modes and they permit the
recovery of energy that is otherwise wasted in vehicle
braking.
a The vehicle displayed was a diesel hydraulic hybrid with a projected 55% improvement in fuel
economy due to the hydraulic hybrid technology. The hydraulic hybrid technology is projected to
increase the cost of a large SUV by about $600, which would be quickly recouped by the
consumer's lower fuel and maintenance costs. Another 30-40% improvement is available through
the conversion of the gasoline engine to a diesel engine.
a Improved fuel economy reduces greenhouse gas emissions, lowers dependence on imported oil, as
well as saves consumers money.
a Full hydraulic hybrid technology means
that the conventional transmission and
transfer case have been removed and
replaced with a hydraulic drivetrain;
EPA has also replaced the large gasoline
engine with a small diesel engine.
a The hydraulic components are easily
packaged in this vehicle because the
conventional transmission and transfer
case were deleted.
Hydraulics are an exciting alternative to batteries for making a hybrid vehicle-while electric hybrids
add a battery pack, electric generator/motor, and power electronics, hydraulic hybrids add an
accumulator (which stores energy as highly compressed nitrogen gas) and one or more hydraulic
pump/motors.
EPA and its partners have active programs to demonstrate the commercial potential of hydraulic
hybrids.
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Clean Automotive Technology,
Innovation that Works
&EPA
www.epa.sov/otaq/technolosy
Full Hydraulic Hybrid SUV
Projected Design Examples
Large 4WD SUV
Diesel Engine
Accumulators
Weight Increase
City
Highway
Combined
Cost Increase
Consumer Payback
Net Lifetime Savings
O-to-60 mph acceleration
(at test weight)
Max sustained speed
(at GVWR)
Max sustained grade
(at 70 mph at GVWR)
GVWR plus towing
(at 65 mph at 5% grade)
Medium Engine Package
3.8-liter (i?o kw)
15 gals
360 Ibs (163 kg)
Fuel Economy - label values
32mpg
22mPg
27mpg
Cost/Payback
$2,200
2.5 years
$4,800
Performance
8.9 seconds
108 mph
9.1%
12,000 Ibs
• Small Engine Package
1.9-liter (95 kw)
22 gals
125 Ibs (57 kg)
Fuel Economy - label values
33 mpg
23mpg
28 mpg
Cost/Payback
$1,000
1.1 years
$6,300
Performance
11.4 seconds
90 mph
3.5%
6,900 Ibs
Economic assumptions:
Mature high-volume production, vehicle life of 14 years and 188,000 miles,
$1.50 per gallon fuel price, 7% discount rate, and 26% retail price mark-up
For more information: See "Progress Report on Clean and Efficient Automotive Technologies Under
Development at EPA", Interim Technical Report, January 2004, at
www.epa.gov/otaq/technology
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Clean Automotive Technology,
Innovation that Works
&EPA
www.epa.sov/otaq/technolosy
Full Hydraulic Hybrid SUV
Projected Performance Examples
0-70 MPH Acceleration
Full Hydraulic Hybrid SUV
~ Conventional Expedition (5.4Lgas)
— 95 kW, 4-cyl engine, 22 gal accum, 5000 psi max
— 95 kW, 4-cyl engine, 22 gal accum, 7000 psi max
— 170 kW, 6-cyl engine, 15 gal accum, 5000 psi max
— 170 kW, 6-cyl engine, 22 gal accum, 5000 psi max
55 - 70 MPH Passing Acceleration
Full Hydraulic Hybrid SUV
— Conventional Expedition (5.4L gas)
— 95 kW, 4-cyl engine, 22 gal accum, 5000 psi max
— 95 kW, 4-cyl engine, 22 gal accum, 7000 psi max
— 170 kW, 6-cyl engine, 15 gal accum, 5000 psi max
— 170 kW, 6-cyl engine, 22 gal accum, 5000 psi max
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Clean Automotive Technology,
Innovation that Works
&EPA
www.epa.sov/otaq/technolosy
EPA Advances in Hydraulic Components
Charge/Discharge Cycle Efficiency \
Overall Weight \
Weight Reduction \
Specific Energy \
Energy Density \
Power Density \
Specific Costs \
Operating Pressure \
Next Generation - Operating Pressure \
Peak Efficiency \
90+ % Efficiency \
Power Density \
Next Generation - Power Density \
Composite Accumulators
95 % to 99%
240 pounds (22 gallon system)
80 to 90% (from steel piston type accumulators)
~8 kW-sec/kg
>50 kW-sec/gallon
3 kW/kg
$10/kg
5000 psi
7000 psi
Pump Motors
95+%
over 60% of the operating map
5 kW/kg (w/integrated mode valve)
7 kW/kg (w/integrated mode valve)
This hydraulic system can store and re-deliver about
80% of braking kinetic energy back to the wheels.
Regenerating Mode
Propulsion Mode
82% Efficiency
Pump
1—i
Accumulatoi
Shaft
92 ' 100
(92%)
Wheel
Vehicle
Braking
Kinetic
Energy
100
Hydraulic
Motor
Shaft
(98%)
90
(91%)
Wheel
EPA420-F-04-019
March 2004
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