Investigation of the Effect of Rotation Speed on Vibration Responses of Transmission System

In the operating process, it is found the vibration of main reducer reaches a maximum value when certain types of vehicles are running at a speed around 4000 RPM. However, how the rotation speed of engine affects the vibration responses to automobile transmission system has not been investigated theoretically in details. To investigate this problem, the transmission system of automobile is simplified to a drive-final shaft system in this research, and a coupled vibration model of drive-final shaft system is developed. This model is used to simulate the vibration response to transmission system at different rotation speeds. Simulation results show that the torsional vibration responses reach the maximum when the rotation speeds are 3800 RPM and 4200 RPM and the vibration responses of pinion reach the maximum value when the rotation speeds are 4000 RPM and 4200 RPM. Moreover, finite element analysis is conducted to investigate the reason for this phenomenon. It is found that the torsional vibration responses reach the maximum value when the excitation frequency of engine is close to the resonance frequency of drive shafts. This research provides an effective method to analyse the vibration characteristics of automobile transmission system