Dynamic Modelling and Simulation of a New Spring-Based Synchronizer for Electric Vehicle

Compared to the widely used single-speed transmission in electric vehicles (EVs), the two-speed transmission can improve both the dynamic performance and driving efficiency. This paper investigates the new spring-based synchronizer used in two-speed automated manual transmission (AMT). Compared with the traditional synchronizer which uses friction torque to implement the synchronization process, the proposed synchronizer uses torque spring to provide torque to synchronize the speed between target gear and shaft, which reduces the wear caused by friction and decreases the shifting time. To comprehensively study the performance of the new spring-based synchronizer, its dynamic model is built in AMESim software. The shifting time and contact torque are analyzed through simulating the dynamic model, which demonstrates that the new synchronizer can reduce the shifting time and contact torque compared to the traditional friction-based synchronizer. On the other hand, the required shifting force of the spring-based synchronizer is also quite small, so a shift motor with lower power can be used. At the same time, the influence of some key parameters such as the speed difference, spring stiffness, and shifting force is investigated. The optimal parameters are designed to further reduce the shifting time and contact torque.