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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.

The clutch-to-clutch gear-shift process of dual clutch transmission (DCT), which consists of the overlapping of the engagement of the incoming clutch and the disengagement of the outgoing clutch, is a vital stage for the shift quality improvement. The paper investigated an integrated control strategy for the gear-shift process that takes into account the influences of oil pressure of dual clutches and engine speed on shift quality. Firstly, the evaluation indices for the shift quality of DCT were summarized, and the factors affecting the shift quality were analyzed. Secondly, an integrated control strategy for dual clutches pressure and engine speed was proposed. Through analyzing the states of clutch in the gear-shift process and the desired traction torque for different gears, the strategies of variable oil pressure and invariable oil pressure were determined for every gear-shift process.