Actuator

Abstract

There is provided an actuator in which an worm is rotationally driven by an electric motor, and in which an angular velocity of the electric motor is repeatedly fluctuated so that the rotation of the worm is carried out as if the worm is oscillated in the rotational direction thereof, to thereby decrease contact friction of the worm against a worm wheel, resulting in an improvement of an efficiency of force transmission of the worm gear mechanism. Although the electric motor 20 is inherently controlled so that an output shaft 21 thereof is rotated at a target velocity based on a velocity command, a drive control section 40 controls the angular velocity of the output shaft 41 so as to be repeatedly increased and decreased with respect to the target velocity so that the angular velocity of the worm 11 is finely fluctuated, and thus the fluctuation of the angular velocity may be regarded as a fine general-oscillation of the rotating worm 11 in the rotational direction, whereby friction between the gear faces of the worm 11 and the gear faces of the worm wheel 12 can be decreased, resulting in an improvement of the efficiency of force transmission of the worm gear, and in increase in a driving force and a torque value to be transmitted to an object to be driven by the actuator.

Dependencies are inferred from the claim text.