Analysis and optimization of the gear-shifting process for automated manual transmissions in electric vehicles

• Published in: Proceedings of the Institution of Mechanical Engineers. Part D, Journal of automobile engineering Journal of automobile engineering, 2017-11, Vol.231 (13), p.1751-1765
• Main Authors: Qi, Xiaowei, Yang, Yiyong, Wang, Xiangyu, Zhu, Zaobei
• Format: Article
• Language: English
• Subjects: Automation; Electric contacts; Electric vehicles; Finite element method; Linearity; Mathematical models; Model accuracy; Process parameters; Stiffness; Transmissions (automotive); Transmissions (machine elements); Trucking industry
• ISSN: 0954-4070; 2041-2991
• DOI: 10.1177/0954407016685461

In recent years, it has been a trend for an automated manual transmission to be adopted as the powertrain for an electric vehicle. However, the strong degrees of jerk and power interruption during the gear-shifting process affect the shifting quality and restrict the application of automated manual transmissions. Therefore, it is a currently popular research topic to find an optimal method to improve the shifting qualities of automated manual transmissions. In this paper, the clutchless shifting process is analysed on the basis of a dynamics model of an automated manual transmission in an electric vehicle, and the parameters are optimized to improve the shifting quality using a defined comprehensive evaluation index. First, the dynamics model of the shifting process for an automated manual transmission is established by considering the stiffness, the damping and the non-linearity contact backlash of the gear mesh and the synchronizer. The whole shifting process is carried out in MATLAB/Simulink and compared with that in the Adams model and bench experiments to prove the accuracy of the dynamics model. Then, the factors of the shifting quality, which include the shifting force and the control accuracy of the speed of the driving motor, are quantified. With the comprehensive evaluation index, all the main factors are described in a cobweb model diagram to find the optimal parameters of the shifting process. The results show that the comprehensive evaluation index can be reduced by 23% by regulating the parameters of the shifting process. This study may be conducive to improving the shifting quality of automated manual transmissions in electric vehicles.