Synchroniser control with proportional pressure reducing valves and displacement feedback

In order to improve the shift quality of automatic transmission with synchroniser, a synchroniser electrohydraulic control system equipped with the proportional pressure reducing valves is proposed. The principle of the control system is introduced in detail. The PID controller is used to realise closed-loop control of shift displacement to achieve the synchronisation. A numerical model and a test apparatus have built up to validated the control performance. The simulated and measured engagement and disengagement of the synchroniser with the proposed control system are investigated in detail. The results indicate that the shift displacement is controllable by changing the cylinder chamber pressure. The back pressure value is useful for a smooth synchroniser operation. It is determined by the sleeve motion and the throttle parameter. The back pressure affects little on the synchronisation stage during the engagement process. The proposed method can be used for the optimising design of the electrohydraulic system for the synchroniser control.