Research On Control Strategy And Temperature Field Simulation Of Wet Multi-plate Clutch Of CVT Vehicle

With the development of the modern automobile industry, people place more andmore demands on fuel economy and drive comfort of automobile. The continuouslyvariable (CVT) transmission can relatively save fuel and improve exhaust emissionbased on the continuous transmission ratio and it also possesses some other advantagessuch as smooth power transmission and convenient operation. So CVT is attractingmore and more people’s attention. The starting clutch control is one of difficulties ofCVT control technology. Currently, Wet multi-plate clutch as one of several commonlyused starting devices has been widely used because of some advantages such as simplestructure, low cost, laying out conveniently, easily controlled and so on.This paper focuses on the CVT vehicle equipped with wet-plate clutch as itsstarting device and researches on the control strategies of starting and creeping. Inaddition, this paper also makes simulation analysis of friction pair’s temperature risecaused by clutch’s slipping during the two processes. The major tasks are as follows:1) The full vehicle dynamic model is built aimed at the starting and creeping workconditions. The stage starting control is proposed on the basis of optimizing thestarting control principle for keeping the engine speed constant. The creeping controlstrategy is formulated based on the multi-mode control algorithm.2) The stage starting and creeping control model are built with the use ofMATLAB/Simulink simulation platform. The related change curves of sliding frictionwork are obtained by analyzing the simulation results of different pedal opening anddifferent change rate of pedal opening, several different load and road slope and so on.3) Based on the heat transfer theory, the modes of heat transfer of the wetmulti-plate are analyzed. According to the simulation results of starting and creeping,the initial and boundary conditions for thermal analysis of clutch are acquired. By usingthe finite element analysis software COMSOL, the transient temperature and some otherheat load features of3kinds of work conditions that may generate a lot of friction heat,i.e. starting with a big pedal opening, starting many times in a short time and creepingfor a long time are analyzed. At last, the restrictive conditions for safely working of wetmulti-plate clutch are given.