Analysis on Meshing Efficiency of Straight Conjugate Internal Gear Pair

To improve the performance of thermal power as a whole for an underwater vehicle, the meshing efficiency of straight conjugate internal gear pair, which substitute for external gear pair of sea water pump, fuel pump and lubricating oil pump for an underwater vehicle, is investigated, the meshing characteristics of straight conjugate internal gear pair are analyzed on the basis of tangent polar coordinate, and a meshing efficiency function is derived based on the instantane-ous efficiency. Moreover, a formula for calculating the average meshing efficiency(short for meshing efficiency) is ob-tained through integrating in the meshing interval, and the influence of gear deformation on meshing quality is analyzed. Taking the gear pair in NBX3 pump for example, the curves of friction coefficient and gear ratio versus meshing effi-ciency are simulated, and the following conclusions are drawn: 1) tangent polar coordinate is feasible and convenient for analyzing the meshing characteristics of the internal gear pair; 2) meshing efficiency decreases with the increase in fric-tion coefficient, and the decreasing rate of meshing efficiency accelerates with increasing friction coefficient; 3) meshing efficiency decreases with the increase in gear ratio, and the straight conjugate internal gear pair gets higher meshing efficiency than involute internal gear pair.