The Development of an Electro-Hydraulically Controlled, Five-Speed Transmission for a Hybrid Electric Vehicle

In an effort to develop a five passenger sedan capable of achieving the Partnership for a New Generation of Vehicles (PNGV) objectives, a 1996 Ford Taurus sedan was converted into a parallel drive, hybrid electric vehicle. This vehicle was designed to retain, to the greatest degree possible, the basic driving characteristics of the conventionally powered vehicle. To achieve the high PNGV fuel economy goals, every effort was made to reduce weight and to use components that are more efficient than those of the original vehicle. The OEM automatic transmission has been replaced with a five-speed, manual transmission which was adapted from an earlier model year production Taurus SHO vehicle. In order to provide the driveability of an automatic transmission, an electro-hydraulic control unit was designed and built. This unit automatically engages the clutch and shifts gears as required during vehicle operation. The design of the vehicle, including a detailed discussion of the transmission system, is reported.