Design And Simulation Of The Planetary Anti-backlash Mechanism

Planetary reducer has been widely used in civil and military industries due to its large transmission ratio,compact structure,high transmission efficiency and long service life.In the design process of planetary gears,in order to ensure a constant transmission ratio and eliminate the backlash error generated during reversal,each parameter of the gear is designed without backlash meshing.However,in the actual production process,it will inevitably produce backlashes due to errors in the processing,installing,and wearing during uses environments.The presence of the backlash will change the contact states of its teeth,resulting in repeated heavy impacts of contact-disengagement-re-contact.This vibration,noise and dynamic load caused by the backlash seriously affect the dynamic characteristics of the planetary reducer,which affects the transmission efficiency and working stability of the system in turn.Therefore,it is necessary to study the influence of the backlash on the dynamic characteristics of the planetary reducer.At the same time,in order to eliminate or reduce the above negative effects,it is necessary to design a planetary anti-backlash mechanism and simulate the anti-backlash effects.The working principle of the planetary reducer is first briefly introduced in this article.Then the system model of the planetary reducer is established in the SimulationX dynamic software and the corresponding simulation parameters are set.The influences of the backlashes(including a inner backlash and a outer backlash),the input speeds of the sun gear,the loads and its moments of inertia on the fluctuations of the output speeds of the planetary reducer are discussed through a control variable method.The relationship between the peak frequency and the speed peak of the planetary carrier’s angular velocity and the above factors are obtained.Secondly,a planetary anti-backlash mechanism based on a torsion bar is introduced in this paper.By modeling and simulating it in the AMESim modeling and simulation platform,and comparing the output speed fluctuation diagrams before and after the backlash eliminations of the planetary reducer under the two special conditions of starting and reversing,the correctness and feasibility of the design of the anti-backlash mechanism are verified.At the same time,the influence of the above parameters on the anti-backlash effect is analyzed by changing the stiffness coefficients and damping coefficients of the torsion bar.Based on this,we use a genetic algorithm optimization function that comes with AMESim software to set the corresponding objective function and constraint conditions,and obtain the best stiffness and damping coefficients of the torsion bar under the existing parameters.Finally,in order to obtain the best stiffness and damping coefficients,on thebasis of studying and understanding the working principle of the hydro-pneumatic spring,a hydro-pneumatic torsion bar with adjustable stiffness and damping is designed.Taking it as the research object,the mathematical model is established according to the physical equations.The Simulink software is used to model it and analyze the stiffness and damping characteristics.The relationship between stiffness and damping forces and the rotation angle of the torsion shaft is obtained respectively.Then the influences of the above parameters on the stiffness and damping characteristics are obtained by changing the values of oil density,cylinder bore diameter,torsion shaft diameter,orifice area and other factors.