Research On Reliability Calculating Method Of Metal V-belt CVT In Sliding Friction Transmission Condition Based On The Film Thickness

The sliding friction transmission reliability of metal v-belt continuously variable transmission(CVT) has important effects on CVT transmission efficiency, but the clamping force control strategy on sliding friction driving conditions involves many parameters, some of which are difficult to obtain, thus making the reliability of the clamping force control hard to conduct real-time assessment. In view of this, this article, based on the elastohydrodynamic lubrication theory, established the mathematical model of sliding friction transmission film thickness, obtained the key parameters necessary to solve the model via experiment, got the distribution of film thickness between the element and the pulley with multi-grid method and combined the probability analysis method to study the reliability of film thickness. The main work of this thesis is as follows:(1) The structure and the transmission mechanism of metal v-belt CVT were analyzed in detail, the generation mechanism of slip in the process of metal v-belt CVT transmission and its influence on torque and efficiency was studied. It also discussed the method of reducing the torque loss and efficiency loss, and illustrated the relation between the sliding friction transmission mechanism and the CVT transmission reliability.(2) The mathematical model of oil film thickness under the steady state was established based on the elastohydrodynamic lubrication theory, the data of the pressure between the element and the pulley necessary to solve the model was obtained through the experiment and other parameters needed for the model were presented.(3)The numerical solution for the elastohydrodynamic lubrication film thickness mathematical model was conducted with the multi-grid method and the distribution of oil film thickness between the element and the pulley was obtained.(4) Considering the influence of belt and pulley surface topography and other factors on the oil film thickness, the reliability of oil film thickness was calculated with the variation coefficient method based on the minimum oil film thickness formula of elastohydrodynamic lubrication. This method can be further applied in the clamping force control strategy.This thesis regarded the reliability of the metal v-belt CVT on sliding friction transmission as the research object, and in view of the fact that the sliding friction transmission reliability is difficult to measure in the process of transmission, put forward a feasible solution which is of great significance to the research and development of the domestic CVT.