Chrysler Corporation LLC and the Environmental Protection Agency have agreed to work on the development of a new hydraulic hybrid powertrain technology that would be suitable for use in future larger-size passenger vehicles. The goal of the collaboration will be to effectively downscale and refine a system originally developed and patented by the EPA at its Ann Arbor, Michigan, R&D labs which is now being used successfully in various industrial applications, mostly notably on heavy trucks. The joint announcement was made in Ann Arbor by Sergio Marchionne, Chrysler Group CEO, and Lisa P. Jackson, Agency Administrator for the EPA. The Chrysler/EPA program is completely separate from the automaker's own conventional gasoline/electric hybrid efforts, the first of which are set to arrive with the 2013 model year.
Unlike conventional gasoline/electric hybrids, the hydraulic alternative relies on the use of pressurized fluid rather than electricity to provide extra motive force to the drive wheels. In this case, engine torque would be used to drive a compressor that can charge a 14.4-gallon accumulator vessel containing the hydraulic fluid at up to 5,000 psi. That stored energy would then be applied to a hydraulic motor on the driven axle, which would also help return fluid to the accumulator under deceleration. As long as sufficient pressurization to drive the motor remains in the accumulator, the internal combustion engine itself can be shut down completely.
Marchionne stated that this currently one-off research project involves creating a next-gen hybrid hydraulic package that will be compatible with a Chrysler Town & Country minivan equipped with a 2.4-liter gasoline engine. According to Jackson, the hydraulic hybrid system would be capable of delivering a 30-35 percent gain in overall fuel economy and reduce greenhouse gas emissions by 25 percent. While offering serious cost advantages compared to gasoline/electric hybrids with their heavy and expensive battery packs, perfecting this hydraulic variation for passenger car applications will entail overcoming a variety of packaging, noise and operational refinement hurdles.