Dynamics and simulations of shifting in a dual clutch transmission

In this paper a finite element model of a dual clutch transmission (DCT) equipped rear wheel drive powertrain is developed for the study of transient dynamics during clutch-to-clutch shifting. Damped free vibration analysis is performed to identify natural frequencies and damping ratios. These results indicate that damping in the DCT is significantly lower than in comparable automatic transmissions. Clutch pressure signals are employed from a constant torque shift control algorithm with engine throttle angle control for transient simulations. These simulations demonstrate inadequacy of the sole use of torque control for providing high quality gear shifts in DCTs. To rectify this issue the torque phase of shifting was restricted by applying a ramp increase in clutch torque to reduce pressure overshoot during simulations. Results demonstrate a reduction in post lockup transients; however it is suggested that inclusion of time delay in shift control must be considered to achieve best possible performance