Study On Control Strategy Of Clutch In Limiting Conditions For CVT

Depending on the driving situation, CVT can provide the optimal transmission ratio via continuous changes of optimal transmission ratio which make the motor work in the ideal state to achieve the best match with CVT. Due to it can get the best coordination control between dynamic quality and economy of vehicle, so become the ideal transmission system for cars especially for the economy car.Among all kinds of CVT, the Metal V-belt CVT is the most widely used and many companies equip their cars especially Hybrid Electric Vehicle with CVT, such as TOYOTA, NISSAN and VOLKSWAGEN. CVT deliver power delivered through friction, so clamping force control and transmission ratio control and starting-clutch control have come to the challengeable key technology for CVT traditional transmission system which can improving the efficiency and the starting capability.Study on CVT wet type multiple disk clutch and its actuators, this paper aims at the limit condition during the vehicle starting to make a simulation study which is based on the fussy control strategy of clutch and the vehicle starting.Firstly, it makes a dynamics analysis on process of the clutch getting to start. And it will set up a dynamical model to analyze the evaluation index and its influencing factors. Secondly, it will take advantage of Matlab/simulink to set up simulation model, including clutch hierarchial fuzzy control model, engine numerical model, the throttle signal module, clutch dynamics calculation module and clutch lock-up control logic module.Thirdly, in order to solve the problem in the limiting conditions and friction work, it make an analysis on the clutch starting to propose the clutch starting control strategy in limiting conditions. In addition, it takes advantage of Fuzzy Logic Toolbox of Matlab to make a design of the fuzzy controller.At last, it takes advantage of simulation model to make a simulation analysis of the clutch engaging process, and then it makes a comparison between the simulation result and the result under the conventional PID control strategy. It shows that if the positive pressure and its increase rate between clutch active disc and clutch slave disc can be controlled reasonably, it can satisfy the requirement of its ride performance and working life. The fuzzy controller based on the fuzzy controlling theory and controlling strategy aiming at extremely situations, they can satisfy the controlling requirement of clutch starting which is quite feasible and effective.