Study On Wet Starting Clutch Control Strategy And Algorithm For CVT Auto

Continuously Variable Transmission (CVT) as the ideal gear is increasingly being used in cars, and it has broad prospects for development. Compared with other automatic transmission, CVT has many advantages, such as simple structure, excellent performance, stepless speed, etc., so it has attracted more and more people’s attention and achieved rapid development. The world’s major car manufacturers have carried on CVT a lot of researches, especially in metal belt type continuously variable transmission. CVT control technology including the clamping force control, the ratio control and the start clutch control, and the start clutch control technology is the most important and difficult.The common starting clutch of CVT includes torque converter clutch, wet clutch and electromagnetic clutche. Torque converter is widely used in various auto transmissions with its twisting effect in low speed and damping effect at the start, and its control technology is relatively simple. Wet clutch has broad prospects for development and market space with compact, low cost, high efficiency, easy to implement electronic control, etc..Firstly, this paper introduces the structure principle of CVT, and makes motion analysis and dynamic analysis of shift principle of CVT. Secondly, establish the MATLAB model of the engine, the torque converter, the dynamic model of wet clutch, the clutch pressure control, the car drag torque, the reverse control, the brake control and the down a long slope control and etc. Thirdly, combined with the advantages of wet clutch PID control and fuzzy control, this paper proposed fuzzy adaptive PID control based on slip. In addition, it developed the control strategy of the torque converter lock-up, the reverse start, the down a long slope and the constant engine speed.At last, it makes compared simulation analysis between the start control with torque converter, the start control without torque converter and the start control for engine constant speed, and makes analysis on the reverse start control, the brake control and the down a long slope control. The emulation result proves that the fuzzy self-adaptive PID control based on slip ratio for CVT clutch control is able to control the clutch engaging process well, making vehicles a smooth and rapid launch, and verify that the reverse start, the brake contro and the down a long slope control strategy are correct.