Study On The Wet-Clutch Control For CVT Based On Fuzzy Control Theory

Starting device for Continuously Variable Transmission (CVT) has three kinds of construction: Electromagnetic-clutch, Multi-plate Wet-clutch and the Torque Converter. As widely acknowledged, the torque converter performs very well during the vehicle starting. But complicated structure, high cost and low efficiency are its obvious weakness. So the new generation starting device of Automatic Transmission mostly applied with Multi-plate Wet-clutch or Electromagnetic-clutch. To make use of reasonable control strategy for starting clutch imitates the performance of the torque converter and makes it more efficiently. So clutch-engagement control is one of the pivotal techniques of Continuously Variable Transmission. The paper studies on the multi-plate wet-clutch for CVT ,The main work has been completed as follows: 1, Establish the math models of the clutch-engagement which including Dynamic model of clutch-engagement, the model of high speed on-off valve and the model of clutch hydraulic cylinder. Assessment index and influence factors of clutch-engagement have been made certain. Assessment index include impulsive degree and dissipated energy. There are a lot of influence factors on the process of clutch-engagement, such as depression of accelerator-pedal, depressing speed of the accelerator-pedal, engine rotational-speed, engine torque, road resistance, load and friction coefficient. A conclusion has drawn from dynamic math models that if the clamping force and its increasing rate between initiative disk and driven disk of the clutch is controlled reasonably, namely making use of the reasonable control strategy for the pressure and its increasing rate in hydraulic cylinder,the engagement process of clutch will be smooth and the clutch life will be more longer.