Experimental investigation of macro-slip in a pushbelt CVT variator

One way to further reduce the fuel consumption of passenger cars that are equipped with a pushbelt continuously variable transmission (CVT) is to improve the CVT efficiency by lowering the clamping forces in the variator. This approach requires the application of active control of the slip between the belt and the conical sheaves, which demands for a reliable and accurate dynamic variator model that describes the variator characteristics in the applicable slip range. In this paper, the dynamic variator model is investigated in detail, with emphasis on the torque transmission. As a first step, the torque transmission in stationary situations is investigated, in which it is generally assumed that macro-slip occurs on the pair of conical sheaves with the smallest wrapped angle. In this paper, it is experimentally shown that macro-slip only occurs on the pair of conical sheaves with the smallest wrapped angle for the extreme ratios Low and OverDrive in stationary situations