Shift dynamics and control of dual-clutch transmissions

Shifts in a dual-clutch transmission (DCT) are realized by torque transfer from one clutch to another without traction interruption due to the controlled slippage of the clutches. The timing of engagement and disengagement of the two clutches is critical for achieving a smooth shift without engine flare and clutch tie-up. This paper presents an analytical model for the simulation, analysis and control of shift dynamics for DCT vehicles. A dynamic model and the control logic for the integrated vehicle have been developed using Matlab/Simulink as the simulation platform. The model has been used to study the variation in output torque in response to different clutch pressure profiles during shifts. Optimized clutch pressure profiles have been created for the best possible shift quality based on model simulation. As a numerical example, the model is used for a DCT vehicle to simulate the wide-open throttle performance. Vehicle launch and shift process are both simulated to assess transmission shift quality and validate the effectiveness of the shift control.