A Rubber Belt CVT for Front-Wheel-Drive Cars

A wide ratio, rubber V-belt driven, continuously variable transmission was designed, built, and operated in a 1.7 liter engine, front-wheel-drive car. A new V-belt under development with transverse stiffening elements is used in the demonstration CVT. Engine operation is controlled to a specified operating line by the CVT mechanical control system. The analytically determined belt side forces are varied with the torque load to maximize belt life.

Dynamometer tests showed a 17.7% improvement in mechanical efficiency over a 3 speed automatic transmission. Vehicle fuel economy tests showed a 15.5% improvement for the EPA driving cycle. Driveability is improved by the smoothness of operation and the absence of discrete ratio changes. The design method described is adaptable to different types of sheave control systems.