Patent ID: 7624657

Claim:
A motor-driven actuator comprising: a housing; an electric motor contained within the housing and having a motor shaft rotating about an axis; a piston mounted within the housing, in contact with the housing, and slidingly coupled to the housing, wherein the piston includes a tubular front portion, an end wall, and a rear portion extending from the end wall opposite the front portion, the rear portion including a rack; a piston rod mounted within the housing, in contact with the housing, slidingly coupled to the housing, and resiliently coupled to the piston for sliding movement of the piston rod relative to the piston, the piston rod being extendable and retractable with respect to the housing; a spring disposed at least partially within the tubular front portion of the piston, bearing on the end wall of the piston, and bearing on the piston rod, urging the piston and the piston rod apart from each other; a speed-reduction stage including speed reducing gears and a drive shaft, coupled by the speed reducing gears to the motor shaft, and rotating the drive shaft about an axis parallel to the axis of the motor shaft, upon rotation of the motor shaft; a speed and direction-change stage coupled to and driven by the drive shaft and rotating a wheel gear about an axis substantially perpendicular to the axis of the motor shaft; and a driving stage coupled to and driven by the wheel gear, engaging the piston and sliding the piston within the housing, along a direction parallel to the axis of the motor shaft, to extend and retract the piston rod relative to the housing, along the direction parallel to the axis of the motor shaft.