Theoretical Study On Dynamic Design Of RV Reducer Based On Time-varying Stiffness Effects

Aiming at the requirements of transmission accuracy,transmission efficiency,noise and service life of RV reducer.Firstly,the dynamic transmission characteristics of RV reducer were studied through establishing the dynamic model.Then,the optimal tooth profile modification value was calculated with the maximum transmission torque as the optimization objective on the basis of dynamic transmission characteristics.Finally,combined with the problems which exist in the study of dynamic transmission characteristics and the optimization calculation of tooth profile modification,the importance of studying the actual meshing interval of cycloid gear was introduced.The research contents and results of this paper are as follows:Based on the Ishikawa formula,the contact stiffness formula of planetary gear was established by comprehensively considering the influence of contact ratio of spur gear on the meshing stiffness.By analyzing the radial load of needle roller bearing and tapered roller bearing,the corresponding radial time-varying stiffness model was established.On the bases of the meshing stiffness between the cycloid gear and the pin gear,the contact stiffness between the pin gear and the pin gear housing was increased,so a more accurate contact stiffness model of the cycloid gear was established.It provides a basis for the study of the dynamic characteristics of the RV reducer and the calculation of the actual meshing interval of the cycloid gear.In the dynamic aspect,the dynamics model of RV reducer which contains 29 degrees was established in this paper.And according to the dynamic model,the dynamic contact stress,dynamic torsional stiffness and dynamic transmission error of cycloid gear were obtained.Which provides theoretical basis for optimizing calculation of cycloid gear profile modification and improving the life and transmission accuracy of RV reducer.Aiming at the optimization of tooth profile modification of cycloid gear,a multi-factor coupling relationship model was established,and the design variables were extracted.Under the constraints of satisfying transmission characteristics such as transmission accuracy,allowable contact stress,transmission torque and so on,the maximum load torque was taken as the optimization goal,and the meshing interval of cycloid gear was automatically selected and optimized by optimization algorithm.So that the optimal tooth profile modification value was obtained.In view of the difficulty in confirming the meshing interval of cycloid gear during the analysis of dynamic transmission characteristics and the problem of constraint redundancy in the calculation of tooth profile modification optimization.Based on the time-varying torsional stiffness model of key components and considering the influence of assembling clearance,the torsional stiffness of cycloid gear was calculated according to the measured torsional stiffness.According to the principle that the continuity of the meshing point position and the initial meshing point position of the cycloid gear did notchange with the increase of torsional stiffness,all of the meshing intervals of cycloid gear satisfying the requirements of torsional stiffness were calculated.On this basis,through analyzing the cycloid gear meshing interval under different torques,the actual meshing interval was obtained.Thus,a more accurate dynamic model can be established,and a more appropriate constraint condition is provided for the optimization calculation of the tooth profile modification value,which also provides the necessary foundation for the study of tooth profile modification value of RV reducer throuth reverse engineering.