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

The metal pushing V–belt CVT is a type of ideal transmission for passenger cars, which possesses many advantages such as simple structure, excellent capability, easy operation, low cost, high efficiency, low air pollution, and so on. The key control technologies of CVT include speed ratio control, clamping force control and the starting-clutch control.Just all of them achieving optimal control state, the car's best capability can be attained.There are some basic types of starting-clutch such as hydraulic torque converter, electromagnetic clutch and multiplate wet clutch. Multiplate wet clutch which is a type of starting-clutch with particular structure, high efficiency and low price is used widely. The control strategy of clutch based on fuzzy technique of multiplate wet clutch for CVT and its actuator are researched in this article.The dynamic model for clutch engageing is established, the assessed standard and influencing factor have been gained.The simulation results show that the demand for smoothly starting and long durability can be achieved through accurately controlling the clamping force.Based on test bed, we have got the relation among torque, oil comsumpution and speed, throttle by using of the performance curve fitting of engine as well as the models for engine and a certain domestic car equided with CVT.In actual control processes, we control the clamping force through controlling the frequency of high-speed on-off valves.So we have established the hydraulic model for clutch based on duty cycle.Establishing goal pressure is the nodus for clutch engaging at starting.In this system, our control strategy is that attaining the starting-time through using the fuzzy control for driver intention, and getting the goal pressure according to special arithmetic by integrating the resistance torque and speed of engine.The whole car model is integrated by the dynamic model, hydraulic model, engine model and pressure control model. Comparing with the test results of bed, the simulation results imdicated this controlling strategy of starting-clutch for CVT is feasible and effective and all of the car's performances can be satisfied by using this controlling strategy.