Pressure Control Strategies of Dual Clutches in the Gear-shift Process of Wet-type DCT

Precise control of the pressure of hydraulic oil acting on the dual clutches plays a crucial role during the gear-shift process of wet-type dual clutch transmission (DCT) to implement power shift (i.e., torque-interruption-free gear-shift) and to improve shift quality. Firstly, the hydraulic control system for the dual clutches of DCT were developed, based on that, the dynamic model of the hydraulic control system was built that was further integrated into a dynamic model of wet-type DCT. Secondly, the influence of oil pressure on evaluation indices for the gear-shift process such as shift jerk and friction work were discussed theoretically, and the determinant principle of the target oil pressure of dual clutches during both up- and downshift processes was discussed, a PID controller and a fuzzy controller were also designed respectively to trace the oil target pressure of dual clutches during the gear-shift process of DCT. Finally, the simulation models including PID (proportional, integral, and derivative) and fuzzy controllers respectively for the gearshift process of wet-type DCT were built using MATLAB/Simulink, and the effectiveness of PID and fuzzy controllers were analyzed via simulation comparison. Simulation results show that the PID controller can trace the target pressure precisely, and gets better performance indices regarding shift jerk and friction work.