An enhanced CMM model for the accurate prediction of steady-state performance of CVT chain drives

The paper deals with the theoretical and experimental evaluation of the performance of a CVTchain drive in steady state conditions. We propose an enhanced version of the CMM model, toaccurately predict the slip behavior and the traction performance of the variator. To achievethis objective it is necessary to accurately estimate the elastic displacements of the pulley. Thedetermination of the actual pulley deformation allows to obtain a better estimation of the slidingvelocities between the pins and the pulley surfaces and, therefore, to calculate the amount of totalslip between the primary and secondary pulleys, with a higher degree of accuracy. In contrast tomultibody models, the approach presented here has a very simple formulation and results in a easyimplementation, which allows a complete and fast evaluation of the variator working points. Thetheoretical results are discussed and critically compared with experimental data. The comparisonconfirms the validity of the CMM approach in a large range of clamping forces, speed ratios andtorque loads.