Abstract: Non-circular planetary gears have characteristics such as variable transmission ratios and variable pressure angles, and are widely used in various critical transmission systems. The accurate judgment of their health status is of great significance for ensuring the stable and reliable operation of the entire mechanical system. The time-varying meshing stiffness (TVMS) of non-circular planetary gear pairs is a key factor reflecting the health status of the system. Researchers have conducted extensive studies on the fault TVMS of ordinary gears, but few papers have reported the influence of random pitting erosion on the performance of non-circular planetary gears. Therefore, for the TVMS problem of non-circular planetary gear pairs, The research proposes an efficient and accurate numerical calculation method; The pitting tooth width equation based on the random normal distribution model was established. The influence mechanism of the pitting degree and pitting position on the TVMS of non-circular planetary gear pairs was deeply studied. Finally, the accuracy of the method was verified from the side by experiments. The results show that the range and degree of TVMS decline are mainly determined by the location and degree of pitting erosion. The results of the system dynamic characteristics of the numerical simulation are basically consistent with the experimental results, verifying the feasibility of the method. The research results provide a theoretical basis for the early fault detection of non-circular planetary gears.

Key words: non-circular gear, planetary gear transmission system, random pitting, time varying meshing stiffness