Research On Dynamics Of Planetary Reducer In High Torque Wheel Hub Drive System

In-wheel drive is an emerging driving method.This method uses the motor to drive the reducer,which simplifies the structure of the vehicle and improves the transmission efficiency.It can omit the clutch and differential device,and the motor is installed in the wheel hub.Its environment and noise pollution are low.The hub drive system generally adopts planetary reducer,but when the torque and power of the reducer become larger and larger,the vibration and noise of the gear system will become an important factor that affects the normal operation of the system.Based on the principles and methods of mechanical vibration and gear dynamics,this article takes the two-stage planetary gear reducer in the high torque hub drive system of a400 t mining dump truck as the research object,and analyzes its dynamic characteristics and gear modification.The main research contents of the paper are as follows:(1)The planetary gear dynamic model of the high torque hub drive system is established.The nonlinear factors such as time-varying mesh stiffness and backlash during meshing of high torque planetary gears are considered.The establishment rules of Lagrangian dynamic equations are studied,and the dynamic model of high torque hub drive planetary gear system is established by the lumped parameter method.(2)The dynamics of the high torque hub drive planetary gear system based on structural parameters is studied.On the basis of the established lumped parameter model,the lumped parameter model is solved by the Runge-Kutta method.Then the paper studies the dynamics from the perspective of structural parameters.By changing the size of the structural parameters,the paper studies the changes of the vibration response amplitude of each degree of freedom and dynamic load coefficient.It is found that the change of the structural parameters of the primary sun gear drive shaft,the primary ring gear and the secondary ring gear will have different effects on the vibration amplitude of each degree of freedom and dynamic load coefficient in the dynamic model.The sensitivity analysis is carried out,and it is found that the outer diameter of the primary sun gear drive shaft,the outer diameter and inner diameter of the primary inner gear and the secondary inner gear have an impact on the vibration amplitude and dynamic load coefficient.The influence degree is relatively large,and then these parameters are selected to make a multi-objective optimization of the planetary gear system,which reduces the vibration amplitude and dynamic load coefficient.(3)Tooth profile modification research is carried out.On the basis of the optimized structure parameters,the tooth profile modification parameters are added to the centralized parameter model,and the dynamic model of the high torque hub drive planetary gear system including the tooth profile modification parameters is established.By studying the influence of tooth profile modification parameters on the dynamic load coefficient during gear meshing,the dynamic load coefficient variation curve with each parameter is obtained.Based on this,the high torque hub drive planetary gear system is optimized to reduce the dynamic load coefficient.(4)Tooth lead modification research is carried out.On the basis of the above structural parameter optimization and tooth profile modification optimization,a romax rigid-flexible coupling model is established to study the influence of tooth lead modification parameters on the load distribution of the contact surface and the maximum surface load of the contact surface.Therefore,it can be optimized accordingly to improve the load distribution of each gear contact surface and reduce the maximum surface load of the contact surface.Finally,the optimized value of tooth lead modification is added to the centralized parameter model,and the final result of the centralized parameter model is obtained by synthesizing the optimization of structural parameters and tooth profile modification.