Synthesis of multi-input multi-degree-of-freedom fixed shaft gear transmission configuration for vehicles

Abstract

The rapid development of dual-clutch transmission (DCT) and hybrid and purely electric vehicles stimulate the researches on multi-input fixed shaft gear transmission mechanisms. The multiple degree-of-freedom (DOF) transmission mechanism can achieve a wider range of speed ratio adjustment and more modes under certain space and weight constraints, which is an ideal choice for multi gear transmission. In this paper, a synthesis method of fixed shaft gear transmission configuration is proposed. Based on the established graph theory model, kinematic characteristics of the fixed shaft gear transmission configuration are studied and the shift sequence is determined. Using these characteristics, a derivation method from the basic configuration to the comprehensive gears and shafts configuration is proposed. Multiple parameters such as the synchronizer arrangement and speed ratios are optimized. Finally, the proposed method is vigorously verified by a seven-speed DCT with four DOFs. This method is comprehensive and systematic in designing fixed shaft gear transmission configurations, which can be applied to DCT, transmissions for parallel hybrid electric vehicles, and to some novel multi-input transmissions.