| 摘要 |
An object is to increase the linear driving force in a linear-motion actuator of the type in which the rotary motion of the rotor shaft of an electric motor is converted to the linear motion of planetary rollers disposed between the rotor shaft and an outer ring member by rotating the planetary rollers about the axis of the rotor shaft and also about their own axes. In an actuator of the type in which a plurality of planetary rollers 4 disposed between the rotor shaft 2a of an electric motor 2 and an outer ring member 3 fixed in position around the outer periphery of the rotor shaft 2a are rotated about the axis of the rotor shaft and also about their own axes, thereby converting the rotary motion of the rotor shaft 2a to the linear motion of the planetary rollers 4, a helical groove 7 is formed in the radially outer surface of each planetary roller 4 in which a helical rib formed on the radially inner surface of the outer ring member 3 is received. The helical groove 7 has a pitch equal to that of the helical rib and a lead angle different from that of the helical rib. With this arrangement, the amount of the linear motion of the planetary rollers 4 relative to the amount of the rotary motion of the rotor shaft 2a is determined by the difference in lead angle between the helical groove 7 and the helical rib. Thus, it is possible to obtain a large linear driving force. |
