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Dynamic modelling and simulation of a new spring-based synchronizer for electric vehicle
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on April 06, 2021 by SAE International in United States
Event: SAE WCX Digital Summit
Most of the commercialized electric vehicles only use single stage reducer, but its single transmission ratio makes the overall transmission efficiency of the vehicle be low. A two-speed gearbox with a new spring-based synchronizer is proposed to improve the transmission efficiency and dynamic performance. Compared with the traditional synchronizer which uses friction torque to synchronize speed, the proposed new synchronizer uses spring to provide torque to synchronize the speeds of input gear and output shaft, which reduces the wear caused by friction and compresses the gear shifting time. In order to comprehensively study the performance of the new spring-based synchronizer, its dynamic model is built in AMESim software. The synchronization time and synchronization torque are analyzed through simulating the dynamic model, which demonstrate that the new synchronizer can reduce the synchronization time 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 smaller shifting motor can be used. At the same time, the influence of some key parameters such as the speed difference and spring stiffness is investigated. The optimal parameters are designed to further reduce the shifting time and shifting jerk. Keywords: Electric vehicle, Spring-based synchronizer, Shifting synchronization time, Synchronization torque, Dynamic model