Study On Starting Control And Simulation Of Vehicle With Continuously Variable Transmission System

As the ideal transmission for automobile, it is no doubt that Continuously Variable Transmission(CVT) is the ultimate target which people are always pursuing. As the key technology to realize the industrialization of Continuously Variable Transmission, starting control is absolutely necessarily. In this sense, the study of starting control of Continuously Variable Transmission system has great actual significance on the development of car which can economize on energy and protect environment. Thus, theoretical and experimental researches of starting control of Continuously Variable Transmission system have been carried out in this thesis.It is well known that torque converter is generally acknowledged as the best start clutch for automobile. Based on performance test of torque converter, primitive characteristic curve and mathematical model of torque converter are gained, then the input and output characteristic between engine and torque converter are analyzed, and matching between engine and torque converter has been optimized. From qualitative analysis and quantization evaluation, it is indicated that matching between engine and torque converter after optimized is better than before, so we can say that optimized scheme is right and feasible.The theoretical research of starting control of Continuously Variable Transmission system is based on theory of Continuously Variable Transmission system. Ratio control of CVT is the key for engine running according to ideal curve, and controlling thrust of driving and driven pulley reasonably can improve efficiency and extend life-span of metal belt, and it is coupling relation between control of ratio and thrust. Based on the analysis of motion characteristic of metal pushing V-belt type Continuously Variable Transmission and transmission mechanism of metal belt, the relationship between the thrust of driving and the driven pulley are ascertained under no load and load, and the control model of pressure of driving and driven pulley oil cylinder are established in different ratio and transmitted torque. It is indicated that response characteristic of designed self-adjusted fuzzy controller and robust of control system are well according to result of simulation after ascertaining the optimum economy and performance curve and ratio of CVT being controlled with fuzzy control theory.Starting control of vehicle equipped with Continuously Variable Transmission with torque converter is lock-up control of torque converter clutch actually. the control strategyof standing start is proposed, and model of lock-up dynamic process of torque converter clutch and Continuously Variable Transmission system are established in this thesis. By computer simulation on starting process of vehicle equipped with Continuously Variable Transmission with torque converter and starting performance comparing between vehicle equipped with CVT and five-speed MT, the effect of controlling operating pressure of torque converter clutch with Fuzzy-PI controller is well, and degree of shock brought by lock-up which is in 10m/s3 is satisfied with the need of vehicle; vehicle equipped with CVT is better starting and acceleration performance than equipped with MT.