Design and power loss evaluation of a noncircular gear pair for an infinitely variable transmission

Abstract

A novel noncircular gear design method is proposed in this work based on a modified high-order elliptical pitch curve for an infinitely variable transmission (IVT), and power loss evaluation of a noncircular gear pair is investigated. Modified high-order elliptical pitch curves of noncircular gears are developed by using kinematic equations of the IVT to eliminate cusps between every two neighboring lobes of pitch curves, and improve smoothness of pitch curves and manufacturability of the noncircular gear pair. A power loss evaluation method is developed for the noncircular gear pair by calculating sliding friction power loss of meshing tooth surfaces. The time-varying friction force of every contact position on meshing tooth surfaces of the noncircular gear pair is calculated by using their variable coefficients of friction and sliding velocities. The instantaneous sliding friction power loss of the noncircular gear pair is calculated based on time-varying friction forces and sliding velocities along contact paths of tooth profiles of the noncircular gear pair.