Peterbilt Outlines Hybrid Initiatives
Peterbilt Motors Co. continues development and testing of a full range of vehicles equipped with advanced hybrid technologies that increase fuel efficiency, reduce emissions and improve service requirements.
"Peterbilt's hybrid initiatives include development of both medium- and heavy-duty vehicle platforms and for both on-highway and vocational applications. We will introduce hybrid vehicle solutions to serve a broad range of business requirements, helping customers reduce operating expenses and fostering greater environmental stewardship," says Bill Jackson, Peterbilt general manager and Paccar vice president.
Peterbilt recently announced the latest of its hybrid initiatives – a hybrid electric Class 8 Model 386 configured for long-haul applications. It combines the aerodynamic efficiency of the Model 386 with a parallel-type "direct" electric hybrid system.
"Peterbilt is actively developing and testing four distinct hybrid technology vehicle applications," says Peterbilt Chief Engineer Landon Sproull. "We are proactively researching and testing hybrid technologies, forging strategic partnerships with key suppliers and customers, and integrating hybrid solutions into our already fuel-efficient vehicle designs."
According to Sproull, the four vehicle platforms are:
• A hybrid electric heavy-duty vehicle for long-haul applications.
• A hybrid electric medium-duty vehicle for pick-up and delivery applications.
• A hybrid electric medium-duty vehicle equipped for stationary PTO applications.
• And a hydraulic hybrid heavy-duty vehicle for vocational and stop-and-go applications.
"Focusing our resources on those four key areas allows us to serve a wide range of customer needs and fulfill market requirements," says Sproull. "Each of these vehicle platforms addresses unique customer concerns to reduce operating expenses and comply with various regulatory requirements."
The heavy-duty hybrid electric Model 386, configured for on-highway use, is being developed in conjunction with Eaton and Wal-Mart Stores Inc. It is currently in the testing and evaluation phase and is expected to be available in 2010. Wal-Mart, which operates the nation's second largest private fleet, is supporting development by helping validate the concept and refine the final design.
During third-party testing, the Eaton Hybrid Power System has routinely achieved a 5-7 percent fuel savings versus comparable, non-hybrid models.
The heavy-duty hybrid electric power system features an automated manual transmission with a parallel-type "direct" hybrid system, incorporating an electric motor/generator located between the output of an automated clutch and the input to Eaton's Fuller UltraShift transmission. The system captures energy generated by the diesel engine and recovers energy normally lost during braking and stores the energy in batteries. That electric torque is then sent through the motor/generator and blended with engine torque to improve vehicle performance, operate the engine in a more fuel-efficient range for a given speed and/or operate only with electric power in certain situations.
According to Sproull, in this heavy-duty application of Eaton's hybrid power technology, fuel efficiency and emissions reductions are best achieved both while the truck is rolling or standing still. The system's batteries power the heating, air conditioning and vehicle electrical systems while the engine is off.
Peterbilt has engineered a hybrid electric system, developed in conjunction with Eaton Corp., with its Class 6 Peterbilt Model 330 configured for local pick-up and delivery applications and its Class 7 Model 335 equipped with a fully integrated Terex bucket lift body.
The Model 330 is powered by the Paccar PX-6 engine rated at 240 horsepower and 560 pounds-feet of torque. With the hybrid system engaged, horsepower increases to 300 and torque to 860 pounds-feet. This configuration is ideal for stop-and-go use, such as urban pick-up and delivery, with the hybrid system resulting in 30 to 40 percent greater fuel savings by using electric power to accelerate the vehicle from a stop.
The Model 335 is also powered by the Paccar PX-6 engine which regenerates lithium-ion batteries to electrically operate the PTO. This application of hybrid technology is well suited for municipal and utility applications.
Fuel use, emissions and noise are greatly reduced, and the crane apparatus can operate for up to 28 minutes solely on battery power. The engine automatically starts to regenerate the batteries, which takes approximately 4.5 minutes. During typical stationary operation of the PTO, the engine needs to run only about 1/6th of the time versus non-hybrid vehicles.
Both medium duty hybrid trucks are in limited production this year with full production expected for 2008.
The fourth area of development is hybrid Hydraulic Launch Assist (HLA) technology and is currently being evaluated for vocational and stop-and-go applications, such as refuse collection. This technology is also being jointly developed with Eaton and recycles a truck's kinetic energy to conserve fuel and assist in acceleration.
The system, currently integrated with Peterbilt's low-cab-forward Model 320, increases brake life and reduces engine and transmission wear, potentially extending component life and lowering service costs. It is also more environmentally friendly by decreasing exhaust emissions and noise.
Sproull says the versatile HLA technology can be used to considerably improve fuel efficiency in fuel economy mode or reduce cycle times in productivity mode. In both modes, reduced brake wear of more than 50 percent has been observed.
HLA works by recovering a portion of the energy normally lost as heat by the vehicle's brakes, in the form of pressurized hydraulic fluid. This fluid is stored in on-board accumulators until the driver next accelerates the vehicle.
Fuel savings occur when the stored energy is then used to launch the vehicle during the initial, high fuel consumption start from stop, followed seamlessly by power from the primary engine. In performance mode, the stored energy is released and blended with engine power at launch. This can significantly improve acceleration due to the high power density of hydraulics.
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