Experimental research on the effect of structural parameters on the governing characteristics of a pulley-drive, continuously variable transmission

Abstract

Because of its incomparable advantages over other transmissions especially in some specific conditions, rubber-V-belt, continuously variable transmissions (CVTs) have been extensively applied in low-power vehicles, such as scooters and snowmobiles. The main structural parameters of a CVT evidently affect the driving performance of the vehicle. The effect of one main structural parameter, namely the masses of the flyweights utilized, on the governing characteristics of the CVT is studied, and the mechanism of the effect is explained. First, a mechanical analysis of the drive pulley and the driven pulley of a rubber-belt CVT employed on a snowmobile is conducted. Through the theoretical analysis, the mathematical model of the system running in a steady state is built. Then the principle of parameter optimization, the running resistance of the vehicle, as well as the external characteristics of the gasoline engine applied in the snowmobile are investigated. Finally, experimental research on the structural tuning based on the building of a CVT test rig is carried out. Since it is difficult to change the parameters of some components such as the torque cam and the profile line of the flyweights, the masses of the flyweights are considered as the unique design variables, and different regulating characteristics of the available groups are obtained. Different applications accordingly require corresponding structural design schemes. The experimental results show that the proposed parameter-tuning principle is theoretically correct and practically feasible, which makes it useful for guidance in designing the CVT, as well as the whole driveline.