Patent ID: 8596426
Filing Date: 2013-12-03
Classification: F16D,F16H,Y10T

Abstract:
1. An electric linear motion actuator comprising: a rotary shaft to which rotation of a rotor shaft of an electric motor is configured to be transmitted; a casing; an outer ring member fixed to a radially inner surface of the casing; a carrier; and a plurality of planetary rollers rotatably supported by the carrier for rotation about respective axes and disposed radially outwardly of the rotary shaft between the outer ring member and the rotary shaft such that the planetary rollers revolve around the rotary shaft while rotating about the respective axes as the rotary shaft rotates; wherein a helical rib is provided on a radially outer surface of the rotary shaft or a radially inner surface of the outer ring member; wherein each of the planetary rollers has on its radially outer surface circumferential grooves which are identical in pitch to the helical rib and in which the helical rib is engaged, or a helical groove which is identical in pitch to and differs in lead angle from the helical rib and in which the helical rib is engaged, whereby the carrier is axially moved relative to the rotary shaft as the rotary shaft rotates and the planetary rollers revolve around the rotary shaft while rotating about their respective axes, thereby converting rotary motion of the rotary shaft to linear motion of the carrier so as to linearly drive a driven member; and wherein elastic members are arranged for biasing and pressing the respective planetary rollers against the radially outer surface of the rotary shaft.