Patent attributes
An actuator includes: a rotor assembly including an output shaft having a male screw portion and having a pin attached thereto, and a sleeve having a female screw portion and threadedly engaged with the male screw portion of the output shaft so as to convert a rotary motion of the sleeve into a linear motion of the output shaft; a stator assembly disposed around the rotor assembly; a housing attached to the stator assembly; a coil spring; and a spring holder having slits to guide the pin into an axial direction. In the actuator, the coil spring and the spring holder constitute a fail-safe mechanism and are contained inside the housing, and the coil spring is arranged at such a location that the output shaft is caused to move in a direction to achieve a fail-safe operation. Thus, the actuator incorporates a fail-safe mechanism as an integral unit.
