Time optimal control of gearbox synchronizers for minimizing noise and wear

Hybrid dual clutch transmissions can reduce fuel consumption and CO2 emissions significantly at a low cost, but they will lead to torque interrupt shifts in electric vehicle mode. To improve the shift quality, the shift time should be minimized and the impacts between the sleeve teeth and the idler gear dog teeth after speed synchronization should also be minimized. Besides creating noise, these impacts are also responsible for delaying the completion of shift and contribute to wear in the dog teeth. This paper presents a time optimal control strategy for mechanical synchronizers in a hybrid dual clutch transmission, which includes constraints such that impacts between sleeve and gear dog teeth are minimized. It is demonstrated how a mechanical synchronizer can be modeled as a double integrator system and how the standard time-optimal control solution of double integrator system must be modified such that it can be applied to mechanical synchronizers. The result is a feedback control strategy that guarantees minimum speed synchronization time and minimum noise/wear in transmission. The performance of the controller is verified by simulation.