EPA Debuts Hydraulic Hybrid UPS Delivery Truck
AEN News
Washington - The U.S. Environmental Protection Agency is
debuting a UPS delivery vehicle in Washington today that
uses advanced hybrid hydraulic technology. Based on
laboratory tests, this vehicle achieves over 60-70 percent
better fuel efficiency in urban driving and 40 percent
lower CO2 greenhouse gas emissions. A typical fleet
owner operating just one of these would save up to
1,000 gallons of fuel each year.
The EPA announced on February 10, 2005, a new partnership to demonstrate
the world's first Full Hydraulic Hybrid Urban Delivery Vehicle.
The EPA has been working with United Parcel Service (UPS),
Eaton, International Truck and Engine, and the U.S. Army
to retrofit a UPS truck with a full-series hydraulic
hybrid drivetrain that has been patented by EPA.
Hydraulic hybrid technology uses a hydraulic energy storage
and propulsion system in the vehicle. This hydraulic
system captures and stores a large fraction of the energy
normally wasted in vehicle braking and uses this energy
to help propel the vehicle during the next vehicle
acceleration. The hydraulic system also enables the
engine to operate more efficiently when it is needed.
Hydraulic hybrids draw from two sources of power to operate the
vehicle - the diesel or gasoline engine and the
hydraulic components. In other words, a typical
diesel-powered or gasoline powered vehicle can
be fitted with hydraulic components as a secondary
energy storage system. The primary hydraulic
components are two hydraulic accumulator vessels
(a high-pressure accumulator capable of storing
hydraulic fluid compressing inert nitrogen gas
and a low-pressure accumulator) and one or
more hydraulic pump/motor units.
Hydraulic drivetrains are particularly attractive for vehicle
applications that entail a significant amount of
stop-and-go driving, such as urban delivery trucks
or school buses. A major benefit of a hydraulic
hybrid vehicle is the ability to capture and use
a large percentage of the energy normally lost
in vehicle braking. Hydraulic hybrids can quickly
and efficiently store and release great amounts of
energy due to a higher power density. This is a
critical factor in maximizing braking energy
recovered and increasing the fuel economy benefit.
While the primary benefit of hydraulics is
higher fuel economy, hydraulics also increase
vehicle acceleration performance.
Hydraulic hybrid technology cost-effectively
allows the engine speed or torque to be
independent of vehicle speed resulting in
cleaner and more efficient engine operation.
Hydraulic hybrid systems create a unique opportunity to optimize engine operations. EPA has produced research concept vehicles that demonstrate the hydraulic technology.
One concept vehicle is an urban delivery truck that uses hydraulic "launch assist." This delivery
truck retains its conventional engine and transmission,
but adds on a hydraulics package optimized for fuel
economy. The next generation of hydraulic vehicles
involves fully integrating hydraulic technology.
In this configuration, the "full" hydraulic
hybrid replaces the conventional drivetrain
with a hydraulic drivetrain and eliminates
the need for a transmission and transfer
case. Using the full hydraulic drive in
conjunction with EPA's clean diesel
combustion technology is projected to
improve fuel economy even more.
EPA also has achieved major breakthroughs in designing
hydraulic accumulators and pump/motors to be more efficient,
smaller, and lighter for motor vehicle applications,
which will help improve fuel efficiency. EPA
currently has cooperative research and development
agreements with several private sector partners to
further the development of hydraulics
On March 8, 2004, EPA unveiled the world's first full-sized
hydraulic hybrid sport utility vehicle (SUV) at the
2004 Society of Automotive Engineers (SAE) World
Congress in Detroit, Michigan. EPA retrofitted a
Ford Expedition SUV with a hydraulic full hybrid
powertrain that has been patented by EPA. The
Agency is estimating that this will nearly double
the fuel economy and that a consumer would
recoup the higher vehicle cost in less than
3 years through fuel savings and less brake wear.
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