Defect Analysis and Innovation Design of Synchronizer for Clutchless Automatic Mechanical Transmission

Abstract The synchronizer is a key component of automatic mechanical transmission (AMT) equipped in electric vehicles, but the inertial lock-ring synchronizer (ILRS) commonly used there is not suitable especially for pure electric vehicles without a clutch because of big shift impact. To make the shifting process rapid and smooth, a new synchronizer named pressure-controllable friction ring synchronizer (PCFRS) was designed. Initially, the inevitable shortcoming of ILRS was verified by simulation and test. Furthermore, the mechanical characteristics and advantages of the new synchronizer over ILRS were analyzed. Then, the formulations describing the dynamic transmission based on the working mechanism of the PCFRS were established. Finally, the shifting simulation results with PCFRS and ILRS based on the same operating conditions were compared and analyzed. The research shows that the PCFRS can meet the main shifting evaluation index of an AMT without complex control methods, as well as it takes only 0.2406 s to finish the comfortable and zero-speed-difference shifting. The shifting quality of PCFRS is better than that of the ILRS. It lays a foundation for using the new synchronizer as a part of clutchless AMTs equipped in pure electric vehicles.