Patent ID: 8650977

Claim:
An electric actuator comprising: a housing; an electric motor mounted on the housing; a speed reduction mechanism disposed in the housing for transmitting the rotational power of the electric motor to a ball screw mechanism; the ball screw mechanism being adapted to convert the rotational motion of the electric motor, transmitted via the speed reduction mechanism, to an axial linear motion of a driving shaft; and a rotation sensor mounted to the housing for detecting the position of the driving shaft; the ball screw mechanism comprises a screw thread shaft integrally formed with the driving shaft connected to the electric motor, the screw thread shaft is supported on the housing so that it can move axially but cannot rotate relative to the housing, a nut is inserted over the screw thread shaft, via a large number of balls, the nut is supported so that it can rotate relative to the housing, via a rolling bearing mounted on the housing, but cannot move axially; a swing link, pivoted on a pin projecting from the driving shaft, is arranged to perform a pendulum motion interlocked with the linear motion of the driving shaft; and a magnet is mounted on an end of a pivotal shaft, the pivotal shaft mounted on the housing and forming the reference point of the pendulum motion and the position of the driving shaft is detected by the rotation sensor arranged opposite to the magnet via a predetermined air gap.