|The hydraulic series hybrid uses the combustion engine to power a hydraulic pump/motor. Click to enlarge.
The Hybrid Truck Users Forum (HTUF), a government-corporate partnership led by CALSTART, has selected Hybra-Drive Systems LLC (HDS) to build three identical Class 6 hydraulic series hybrid delivery trucks for real-world testing by UPS, FedEx Ground and Purolator.
Under the new agreement, which is being funded by the Department of Energy, Hybra-Drive will build and deliver three hydraulic hybrid trucks over the next 9 to 12 months. UPS, FedEx Ground and Purolator then will each conduct a 6 to 9 month evaluation of the vehicle. Hybra-Drive anticipates that the evaluations will demonstrate up to a 60% cut in fuel use along with an accompanying reduction in emissions.
We are increasingly convinced that this technology offers a chance to&madsh;fairly quickly—improve the fuel mileage of large trucks. We’ve seen several innovative approaches for this type of vehicle and this is one that our team wants to test to help speed introduction.—Bill Van Amburg, senior vice president of CALSTART
Hybra-Drive, based in Deerfield, Mich., was selected from among roughly four dozen companies that responded to a Request for Proposals issued last September.
A hydraulic hybrid truck uses hydraulic pumps and hydraulic storage tanks to store energy, similar to what is done with electric motors and batteries in hybrid electric vehicles. Fuel economy is increased in three ways: vehicle braking energy is recovered that normally is wasted; the engine is operated more efficiently; and the engine can be shut off when stopped or decelerating.
The US Environmental Protection Agency unveiled the first hydraulic diesel series hybrid urban delivery vehicle in June 2006. (Earlier post.) Since then, several vehicle manufacturers have been working on the technology. Hybra-Drive’s approach differs in that it has developed a hydraulic fluid transmission to go along with the hydraulic pumps and storage tanks that are used to store energy.
Hybra-Drive Systems, working in conjunction with Gates Corporation, Detroit Custom Chassis (a subsidiary of Spectra LMP, LLC) and Morgan Olson LLC, proposed a series hydraulic hybrid vehicle (HHV) based on a Ford chassis for the HTUF validation project.
The HDS Hydraulic Hybrid Power Train (HHPT) system combines a combustion engine with a hydraulic propulsion system that replaces the conventional drivetrain and transmission. The engine, fueled by gasoline, diesel or alternative fuel, operates a hydraulic pump that pressurizes the stored energy hydraulic system to propel the vehicle.
The HDS-HHPT system is designed to add no extra curb weight compared to the standard vehicle and includes unique, cost-effective designs for the variable displacement gear pump and fluid power accumulator system.
Although the corporate members of HTUF have direct experience with operating both hydraulic and electric hybrid parcel delivery vehicles, their objective is to explore other technology options to better understand the relative merits and benefits of different technical approaches. The Hybrid Truck Users Forum allows the corporate members to pool their resources more efficiently and work together to advance alternative fuel technologies.
Michigan Clean Fleet Conference Hydraulic Hybrid Technology Review