Research on shift quality considering nonlinear characteristics

• Research on shift systems has ignored the impact of nonlinear factors on the shifting process. • Established a nonlinear dynamic model of the shifting process considering nonlinear factors. • Conducted a comparative analysis of the differences in shift quality between linear and nonlinear models during the shifting process. • Specifically analyzed the influence of nonlinear factors on shift quality. • Provides a theoretical basis for optimizing shift quality from the perspective of system nonlinear dynamics The adoption of multi-speed transmissions in electric vehicles enhances overall dynamic performance and energy efficiency, but it also introduces shift shock issues. Currently, shift optimization control algorithms based on linearized transmission models are primarily employed to ensure shift smoothness; however, these approaches essentially overlook the impact of the nonlinear dynamic vibration characteristics of gear systems on the shifting process. This paper takes a two-speed AMT without clutch and synchronizer as the research object, considers nonlinear factors, establishes a nonlinear multi-degree-of-freedom torsional vibration model for the shifting process, and the correctness of the model is verified through Adams simulation. The study analyzes the sleeve speed fluctuations and dynamic behaviors at each stage of the shifting process of the linear and nonlinear models, compares the differences in shift quality evaluation indicators between the two models, and conducts corresponding analysis on the situation where shift shock decreases with the increase of rotational speed. The research shows that the stable dynamic characteristic state of the system is conducive to the reduction of shift shock. Subsequently, the study analyzes the influence of nonlinear factors (such as stiffness, damping, and backlash) on shift quality. This research analysis provides a model foundation and theoretical guidance for the optimization of shift quality.