Patent ID: 7605680

Claim:
An electromagnetic actuator, comprising: a first coil; a cylindrical movable body adapted to move along the central axis of the first coil; a first stator including a first plate member provided on the top face of the first coil, a first hollow plate member provided on the bottom face of the first coil, and a first cylinder covering the outer periphery of the first coil; a permanent magnet adapted to fix securely the cylindrical movable body at an end point of its movement; and a second stator provided in succession with the first stator and adapted to control the magnetic flux of the permanent magnet, wherein the second stator includes a second cylinder provided in succession with the first hollow plate member of the first stator, a second hollow plate member provided at one end on the side of the permanent magnet, and an internal cylinder disposed in the second cylinder, the permanent magnet is provided outside the stroke area of the cylindrical movable body so that the permanent magnet can not come in contact with the cylindrical movable body, and when the movable body is in a latched state against the outer load, the magnetic flux generated from the permanent magnet forms a magnetic circuit pass in a closed manner which is defined through the first plate member, the first cylinder, the first hollow plate member, the second cylinder, the second hollow plate member, the permanent magnet, the internal cylinder, and the cylindrical movable body without any air space.