Study On Dynamic Characteristic Of Gear Transmission System Of High-Speed Train

Gear transmission system is one of key system in the high-speed train. By the regulation of the gear transmission system, the traction motor power can be transferred to the required driving force applied to the wheel-set, it play an important role in the power transmission of high-speed train. With more and more high-speed train being put into service, the requirement of product localization is strong. The transmission system has an important effect on the steady transmission and the safety of the high-speed train, so how to design a reliable gear transmission system is a service challenge for the railway researchers. In the tradition vehicle system dynamics, researches are mainly focus on the dynamical performance of a vehicle and the critical components, such as car-body, bogie frame and wheel-set, there is less study on other components. Therefore, based on the vehicle system dynamics and gear system dynamics, the vibration character of the gear transmission system has been investigated in this paper, five main sections has been involved as follows.Firstly, since the vibration of gear transmission system is a typical parametric vibration system, the parametric vibration stability of the gear transmission system in high-speed train was studied. A dynamic model describing the torsional vibration behaviors of the gear system was developed. In this model, the time-varying mesh stiffness of meshing teeth pairs was calculated through finite element analysis, and the mesh stiffness and transmission were expanded using the technique of Fourier series. Based on the Floquet stability theory, the multiple scales method was used to solve the nonlinear differential equations of gear system, and the approximate analytical solution and transition curves that separate stable from unstable regions were obtained. The suggestion of how to select the appropriate parameters of the gear transmission system in high-speed train was also given. In addition, a bending-torsion coupling dynamics model of cylindrical helical gear transmission was also developed to derive the harmonic resonance frequency factors. The frequency response curves of gear transmission system were obtained by using numerical integration method to solve the dynamics equation of gear transmission system.Then, the multi-body dynamics model of motor car including the gear transmission system subjected to the internal and external was established, and the force and moments generated in the gear mesh were considered. In this model, the internal excitations include the time-varying meshing stiffness, damping and gear transmission error, the external excitation include the harmonic torque of asynchronous motor, wheel wear, wheel polygonization and wheel flat. What is more, when the train runs under the wheel-rail stick-slip state, the load torque of the gear transmission system fluctuates and the wheel-rail adhesion appears the negative slope characteristics, it leads to a self-excited vibration of the system, and the bifurcation and stability of the gear transmission system under the self-excited vibration and stick-slip vibration were analyzed.After we get the dynamic meshing force of the gear transmission system, the strength of the gearbox housing of the high-speed train was analyzed. The finite element model of gearbox housing was established, the modal analysis and static strength analysis were carried out. Based on the dynamic forces, the dynamic response of gearbox housing was carried out using a direct integrate method under the excitation of normal wheel, wheel wear and wheel polygonization. In addition, the shock-resistant performance of the gearbox housing was studied.Finally, based on the dynamic response and structural safety of the gear transmission system, the vibration strength of the gear transmission system was evaluated by the vibration intensity and strength. The vibration threshold of the system was suggested. In addition, based on the field test data, the vibration acceleration threshold of gearbox housing was obtained from the probability and statistic point of view, which can provide a frame of reference during the design of gearbox housing.