Evaluation of Power Loss of the Rubber V-Belt CVT

Abstract

Abstract This paper proposes a systematic method for the evaluation of power loss of rubber V-belt continuously variable transmissions (CVT). By observing the interaction between belt and sheaves, the entire belt may be divided into four regions. They are free span, wedging-in, adhesion, and wedging-out regions. Therefore, each region possesses a distinct motion characteristic. Herein, power loss is categorized into speed and torque losses. Since speed loss contributes less than 4% of the total power loss in most operating conditions, only torque loss is considered. The mechanisms causing torque loss may be attributed to the hysteresis of belt bending, compression and shear, and friction due to radial motion of the belt. These loss mechanisms are studied on the basis of motion characteristics in each region. Parameters for loss mechanisms are then analyzed to identify their contributions to the system efficiency. These parameters include external load, rotating speed and wedge angle of the pulley, speed ratio, pre-tension, and thickness and tooth profile of the belt. In addition, an experimental study is performed for verification of the proposed analytical approach.