Patent ID: 7573361

Claim:
A solenoid actuator comprising: a pair of coils that are coupled electrically to each other in series; a core body that has a pair of magnets and a holding member, and moves with respect to the coils when the pair of the coils apply magnetic force to the pair of the magnets in a substantially same direction; and an electromagnetic element converting a magnetic power generated by the magnet into an electrical signal in order to detect a relative position of the core body to the coil, wherein the magnets are inserted into the coils, respectively, the holding member holds the pair of the magnets in common, winding directions of the pair of the coils are opposite to each other, the pair of the magnets are arranged so that magnetization directions thereof are substantially equal in a movement direction of the core body with respect to the coils, the electromagnetic element is arranged facing to the holding member, the holding member is made of a ferromagnetic material or a magnetic material, the holding member is formed so that a distance between the holding member and the electromagnetic element changes when the core body moves with respect to the coil.