Research On Virtual Experimental Platform Real-time Control Of Vehicle CVT

Transmission is regarded as one of the important parts of the automobile transmission system, the development of its science and technology is an evidence of automobile's technology. The metal belt continuously variable transmission (CVT) can use the engine power completely, and change the transmission ratio continuously, so it's an ideal transmission. The metal belt CVT is favored because of the simplicity and compaction of its structure and the convenience of its operated stability and its super performance. Now many automobile factories are decided to research and exploit for it. The electro-hydraulic control system is the key part of the metal belt CVT. The thesis is studied toward the electro-hydraulic control system of the metal belt CVT for Honda car.The development process, the status research and the direction process of CVT are introduced in this paper. The characteristics and the key technology of metal belt CVT are analyzed. Due to the special structure of metal belt, it is much complicated to realize clamping force and ratio control. On the basis of stable force balance, the relationship between clamping force, speed ratio and controlling aim is established, which is based on the working principle of CVT. The electro-hydraulic control system applied in this paper is a double circuit system. The mathematical models of clamp and ratio control valves are established, and the characteristics of valves are analyzed. The applying of the pulse width modulation (PWM) is introduced to control CVT. Due to the special delivery of metal belt CVT the ordinary control methods are not satisfied. The nine point control can solve the problem with great efficiency, and its effect is perfect. The clamp and ratio controllers are designed respectively based on the exploitation of nine point control method. The results of simulation show that the nine point controller can be used in the practical system.The virtual experimental platform real-time control of vehicle CVT is designed, and its resolve project is put forward. The control system of CVT is exploited based on the design periphery circuit of dSPACE. Through MATLAB toolbox of RTW and the real-time simulation system dSPACE, the PWM signals have been achieved andthe real-time simulation of CVT has been made. The process of experiment and the results of control show that the developed electro-hydraulic control system can meet the demand of CVT control, and the system is applicable in practical system. The main characteristics of the electro-hydraulic control system are reflected basically, which is the foundation of further research.