Seibu Electric Machinery Co., Ltd.

Masakazu Mori

Daisuke Kukita

Seiya Shimada

Chikara Kitajima

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 motoris inherently controlled so that an output shaftthereof is rotated at a target velocity based on a velocity command, a drive control sectioncontrols the angular velocity of the output shaftso as to be repeatedly increased and decreased with respect to the target velocity so that the angular velocity of the wormis finely fluctuated, and thus the fluctuation of the angular velocity may be regarded as a fine general-oscillation of the rotating wormin the rotational direction, whereby friction between the gear faces of the wormand the gear faces of the worm wheelcan 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.

Actuator

In an actuator, an electric power supply to a position-detecting detector for an object to be driven can be carried out in a timely manner during a power failure to thereby suppress an electric power consumption in the position-detecting detector, whereby duration time of a power-failure compensation battery can be prolonged, and a variety of detectors can be selected and utilized without limitation in accordance with a use environment and usefulness. During the power failure, a switching meansestablishes a linking state in which an input shaftof a reduction mechanismand a manual inputting meansare linked to each other. When the linking state is detected by a detecting means, an electric power is fed from a batteryto a rotation detector by a control section, so that the control sectioncan obtain a displacement of the object to be driven, based on a signal output from the rotation detector. In a state in which the input shaftof the reduction mechanismcan be manually rotated, the electric power is fed to the rotation detector. Thus, a useless consumption of the electric power of the batterycan be suppressed, and it is possible to suitably obtain the displacement of the object to be driven without an interruption even if the power failure happens.

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Koga, Japan

Masakazu Mori