Research on Frictional Moments and Transmission Efficiency of Planetary Roller Screw
Planetary roller screw (PRS) is a mechanism which converts rotational motion to translational motion. Power transmission of PRS depends on rolling friction of the components. Therefore, it is important to predict the frictional moments and study magnitude of transmission efficiency which caused by frictional moments. The frictional moments are calculated respectively based on the Hertzian contact theory and the method of effective ball considering the elastic hysteresis of material, the spinning sliding of the rollers, the viscosity of lubricating oil and the differential sliding of thread raceways in this paper. Furthermore, a calculating model of transmission efficiency of PRS is developed and the influences of contact angle, helix angle and screw rotational speed on transmission efficiency are discussed.