Cooperative Effect of Controllable Parameters on the Dynamic Characteristics of Dual-Clutch Transmission during the Shift Process

The degradation of the frictional characteristics of a wet clutch, which is repeatedly engaged throughout its entire life, alters the dynamic characteristics of the driveline system. It weakens the effect of control systems that use a fixed control strategy. To solve this problem, the cooperative effect of controllable parameters on the dynamic characteristics of the shift process throughout the full life cycle of the wet clutch was studied. First, an improved dynamic model of the driveline was established. The model considered the clutch’s frictional characteristics, time-varying mesh stiffness of the gears, and torque-coupling effect. Then, the dynamic characteristics of the driveline during the shifting process were analyzed. The model was validated with experimental data. Based on the model, the effect of a clutch’s frictional characteristics on the dynamic characteristics of the driveline was analyzed. To reduce the adverse effects caused by the degradation of the frictional characteristics and obtain an optimal control strategy for the different stages of the clutch life, a control strategy that controls the rising rate of on-coming clutch pressure and threshold of the micro-slip coordinately was proposed. The influence of these two controllable parameters on the dynamic characteristics of the driveline during the shift process throughout the entire life of a wet clutch was analyzed. The results showed that the side effects caused by the degradation of a clutch’s frictional characteristics on the driveline during the shifting process could be attenuated by controlling the rising rate of on-coming clutch pressure and threshold of the micro-slip coordinately.