Modelling Sheave Elasticity in CVT Drives

This contribution presents the modelling of chain and belt CVT drives used in numerical simulations, under special consideration of the elasticity of the pulley sheaves. The system is subdivided into the pulleys, the power transmitting chain or belt and different types of contacts. Since the deformation of the CVT is of major importance for the mechanical behaviour, the elasticity of the colliding bodies has to be taken into account. Due to elasticity and clearance of the shaft-to-collar connection the pulley sheaves tilt. This effect is modelled by a force element. Furthermore as a consequence of the asymmetrical loading, the elastic sheaves deform. Therefore different approaches exist to take this into account, in which the most efficient way is the use of Castigliano’s Strain Energy Theorem. The system contains a large number of contacts. First of all there are three dimensional contacts between the pulley sheaves and the belt or chain elements. In case of belt systems there are further contacts between two adjacent elements, between elements and rings and between two adjacent rings. There exist simulation models for both types of CVTs (chain and belt drives), which are used in industrial applications.