Potential for Fuel Economy Improvements by Reducing Frictional Losses in a Pushing Metal V-Belt CVT

This paper gives an overview of the development of a number of loss models for the pushing metal V-belt CVT. These were validated using a range of experimental data collected from two test rigs. There are several contributions to the torque losses and new models have been developed that are based upon relative motion between belt components and pulley deflections. Belt slip models will be proposed based upon published theory, expanded to take account of new findings from this work. The paper introduces a number of proposals to improve the efficiency of the transmission based on redesign of the belt geometry and other techniques to reduce frictional losses between components. These proposed efficiency improvements have been modelled and substituted into a complete vehicle simulation to show improvements in vehicle fuel economy over a standard European drive cycle. The loss models are implemented into 4-dimensional look up tables based on transmission speed, load, control pressures and operating ratio, to give belt slip and torque loss data for each operating condition encountered. The drive cycle model inputs are from data collected during drive cycle tests and the results are validated using experimental data from chassis dynamometer testing of a vehicle fitted with the standard configuration CVT.