Continuously Variable Transmissions for Cars with High Ratio Coverage

Starting from a classification of car transmissions and from the manufacturers requirements, especially for fuel savings, the potential advantages of continuously variable transmissions permitting to associate low engine RPM with high vehicle speed, are shown.

The control of the engine, transmission and clutch to reach a given optimum, is explained.

Here are given results of simulation or testing of vehicles equipped with a Renault hydrostatic prototype transmission, a 2-mode hydromechanical transmission and a Van Doorne prototype Transmatic.

Highway fuel economy trends are quantified in case of substitution of the conventional S.I. engine for Diesel and/or turbocharged engines.