Research on Motion Relationships and Transmission Efficiency of Planetary Roller Screw

In this paper, taking the planetary roller screw for aircraft electro-mechanical actuator as the research object. The planetary roller screw exist four different designs which are widely used for different applications: these four designs are respectively known as standard planetary roller screw, inverted planetary roller screw, recirculating planetary roller screw and differential planetary roller screw. The composition, thread form, working characteristics and applicable occasions of these four different designs are analyzed and compared. Considering the possible relative slide between components, the angular and axial motion relationships are demonstrated in detail, and the relationships of structural parameters between components were obtained. The force analysis was performed at the contact point to analyze the transmission efficiency. The relation between the transmission efficiency and contact angle, helix angle was also deduced in consideration of the rolling friction and the relative sliding friction of the component. The results show that the transmission efficiency of the planetary roller screw rapidly increases with the increase of the helix angle and then gradually decreases. In addition, the efficiency gradually increases with the increase of the contact angle, and finally tends to be stable.