Dynamic Study On Spiral Bevel Gear System With Backlash Under The Normal Lubrication

The spiral bevel gear transmission system has been widely applied in the fields such as vehicles and helicopters, etc. Its stability and reliability are directly affected by dynamic characteristics of gear system. It is an important way to strengthen the dynamic study of gear system for improving the dynamic performance of gear transmission system. Therefore, it is of importance to develop the dynamic study of gear system.This paper treated a pair of spiral bevel gear pair transmission system as research object. Based on the theories of thermal elastohydrodynamic lubrication theory, gear engagement principle and lumped parameter method, etc, the dynamic study of spiral bevel gear with backlash was analyzed under the normal lubrication. Then, the dynamic responses of gear system were stated under the influence of system parameters and the change rules of dynamic responses were revealed. The main contents and achievements of this paper were listed as follows:1. These parameters had significant influence on the non-linear dynamic behaviors of gear system. Then, the expressions of the lubrication parameters and structure parameters of spiral bevel gear were acquired and the form of third order time-varying mesh stiffness was calculated by the fitting of Fourier series, which established the foundation for the establishment and solution of the gear model.2. Synthetically considering the influence of oil film, mesh stiffness, mesh damping, static transmission error and tooth surface friction, etc, especially the influence of oil film, the more comprehensive and accurate eight free-degree dynamic model of spiral bevel gear with backlash under the normal lubrication was proposed. The backlash function was treated as constant backlash function and time-varying backlash function and the expressions of dynamic mesh force and oil film force were acquired.3. Based on the eight free-degree dynamic model of spiral bevel gear with backlash, the non-linear characteristics of gear system were analyzed under the influence of system parameters, such as the load, bearing stiffness, bearing damping and static transmission error etc. Meanwhile, the motion state of pinion and gear was compared seriously, which provided a foundation for judge the difference of the motion state of two systems. Besides, the dynamic responses of gear system were analyzed under the influence of the load, friction at the contact point, mesh damping and the squeeze stiffness and viscous damping of oil film, etc. And the change rules of normal displacement responses, band responses of mesh frequency corresponding to impact states and dynamic mesh force of gear system were obtained under the influence of above parameters.4. Similarly, based on the eight free-degree dynamic model of spiral bevel gear with backlash, the dynamic responses of gear system were studied under the influence of two backlash function, containing the constant backlash function and time-varying backlash function. The influence of two backlash function for the dynamic responses of gear system was compared. The result showed the effect of time-varying backlash for the vibration characteristics of gear system was more than the effect of constant backlash.