Patent ID: 7075398

Claim:
An electromagnet composed of a coil, a movable iron core adapted to move on the center axis of the coil, and a stationary iron core positioned on the center axis of the coil so as to cover the upper and lower surfaces and the outer peripheral surface of the coil, characterized in that the stationary iron core includes a magnetic protrusion on a side where the movable iron core is inserted, the movable iron core is composed of a plunger and a steel plate fixed to one end face of the plunger, the other end face of the plunger and the stationary iron core, and the steel plate and the protrusion, respectively, are opposed to each other in the same direction lengthwise of the electromagnet, and a permanent magnet is arranged in an area defined by the plunger, the protrusion, the steel plate and the stationary iron core.