Study Gear Pair Dynamic Excitation On The Vibration Characteristics Of High-Speed Train Gearbox Housing

The service environment of high-speed train gear transmission system is very harsh.And the gearbox housing is the key component of the gear transmission system,which is prone to crack failure in service.The main reason is that the gearbox housing is subjected to complex excitation.The gearbox housing is mainly subjected to dynamic excitation of internal gear pair and excitation of external wheel rail and motor harmonic torque.At present,there are many studies on the vibration characteristics of the box subjected to wheel-rail excitation.In this context,the following part studies vibration characteristics of high-speed train gearbox housing with dynamic excitation of gear pair.Firstly,the research status of gear transmission system dynamics by domestic and foreign scholars is described.Based on the theory of gear transmission system dynamics,the dynamic excitation mechanism of gear pair is analyzed.The general straight gear model and the helical gear model used in high speed train are established and their dynamic equations are given.The failure reasons of the gearbox housing and gear in gear transmission system are summarized.Secondly,the rigid-flexible coupling multi-body dynamics model of high-speed train with flexible box was established by using ANSYS and SIMPACK,and the correctness of the model was verified by nonlinear critical velocity.In order to analyze the high-frequency excitation of the gearbox housing by the dynamic excitation of the gear pair,two measuring points were set at the upper box body and the lower box body respectively to monitor the vibration state of the gearbox housing.Then,under the condition of 300km/h speed,the dynamic characteristics of 300km/h speed gear pair are analyzed,and the meshing stiffness,angular stiffness,number of meshing teeth and meshing force during gear transmission are obtained.The dynamic characteristics of its gear pair have time-varying characteristics.Under the working conditions of 200,250 and 300km/h,the vibration characteristics of the rigid and flexible box body under the dynamic excitation of the gear pair are analyzed.Compares the rigid body and flexible body vibration displacement,velocity,acceleration,It is found that the vibration displacement of the rigid and flexible box is basically the same with the high-frequency vibration of the gear pair,but the vibration velocity and acceleration of the rigid and flexible box are different,especially the vibration acceleration of the flexible box is obviously greater than that of the rigid box.According to the maximum statistics of the time domain vibration characteristics of the gearbox housing,the vibration acceleration of the flexible box body under the working condition of 200km/h /h is abnormal.The reason is that the gear mesh frequency 1634 Hz under the working condition is close to the 10 th natural frequency 1667 Hz of the flexible box body,leading to the local resonance of the gearbox housing.Finally,the frequency domain of the vibration acceleration of the rigid box is basically the same as that of the flexible box.The high frequency excitation of the gear pair cannot excite the corresponding high frequency to the rigid box,but it can excite the high frequency to the flexible box.The vibration velocity and acceleration of the flexible box are evaluated by other related vibration evaluation standards,and the result is greater than the specified value of the related standards,because the standard does not consider that the box bears complex external excitation,so other related vibration evaluation standards have no practical reference significance for the evaluation of the box.In order to further evaluate the vibration of the flexible box,the kernel density estimation method is used to evaluate the vibration of the flexible box.It was concluded that the maximum vibration acceleration under the three working conditions was 6.8g,which is within the range of vibration acceleration threshold.