Investigation of planet gear instant center of rotation under three-axis driving differential planetary gear train with graphical analysis using high speed camera

Abstract

A planetary gear train (PGT) is one of the most important components in the hybrid and electric vehicles owing to its high torque-to-weight ratio, light weight, and compactness. But transmission mechanism is still unclear due to structural complexity. Planet gears make PGT complex because of its motion (simultaneous rotation and revolution) and different contact ratio, or meshing stiffness between internal meshing (ring-planet) and external meshing (sun-planet). Although many experimental studies about PGT’s steady condition had been conducted all over the world, no studies have proved motion of planet gear experimentally. In this paper, planet gear instant center of rotation (ICR) is found out based on its velocity distribution and it was proved with direct motion observation on planet gear motion by high speed monitoring. ICR is expected to be effective to estimate meshing transmission errors (MTE) with its feature like light lever. MTEs in a PGT were also discussed based on the fluctuation of trace of ICR, or centrode.