A study on loaded tooth contact analysis of a cycloid planetary gear reducer considering friction and bearing roller stiffness

Abstract

The cycloid planetary gear drives designed in the so-called RV-type play an important role in precision power transmission. Not only the high reduction ratio, but also the shock absorbability is the significant advantage. However, the load analysis of such the drive is complicated, because the contact problem of the multiple tooth pairs is statically indeterminate. The aim of the paper is thus to propose a computerized approach of loaded tooth contact analysis (LTCA) based on the influence coefficient method, either for the contact tooth pairs of the involute stage or of the cycloid stage. The contact points are determined based on the instant center of velocity in the model. On the other hand, the shared loads of multiple contact tooth pairs are calculated numerically with a set of equations according to the relations of deformation-displacement and load equilibrium. The coupled influences of the loads acting on the involute and the cycloid tooth pairs are also analyzed considering the friction on the contact tooth flanks as well as the stiffness of the supporting bearings for the cycloid discs. With an industrial example, the contact pattern with distributed contact stresses and the shared load of each contact tooth pair during operation are simulated with aid of the proposed approach. The transmitted torques on the crankshaft, the displacements of the main components and the efficiency of each stage calculated accordingly are also illustrated in the paper.