Belt Torque Loss in a Steel V-Belt Continuously Variable Transmission

Abstract

To achieve the potential advantages to be gained by the use of a high ratio range, continuously variable transmission (CVT) in an automobile it is important that the system has a high efficiency and that any inherent loss mechanisms are fully understood. This paper investigates the belt-related torque loss in a steel V-belt CVT. Measurements show that the loss is dependent on the secondary pulley clamping force and on the belt configuration and these results are presented in the paper. A semi-empirical model is proposed to explain the loss. The agreement between the measured results and the values calculated from the model is shown to be good. It is also shown that when the system is in an overdrive ratio and a high efficiency is particularly important the torque loss is large and the efficiency is severely limited, probably to less than 90 per cent.