PURPOSE:To prevent the inhibition of the movement of a moving piece, and to scale down an air gap by simultaneously generating attraction forces having components rectangular to moving thrust in the opposite directions where opposite at 180 deg. mutually and offsetting suction forces. CONSTITUTION:A stator 11 consists of a stator yoke 8 and eight stator poles 9A-9H projecting the inside in the radial direction, and a moving piece 12 is arranged inside the stator 11 through a small air gap to the stator poles 9A-9H. The stator 11 is composed by alternately laminating the stator poles 9A-9H, which are (t) thick and the radii of inner circumferential surfaces of which are r1 and r2. The moving piece 12 is constituted in such a manner that magnetic substance disks 13, which are (t) thick and diameters of which are r3 slightly smaller than r1, are formed to a shape that mutually opposite outer circumferential sections 13b are notched extending over 90 deg. in the circumferential direction and mutually opposite sections extending over 45 deg. in the circumferential direction in residual outer circumferential sections 13a having a radius of r3 are displaced only by t/2 in the same axial direction, and the disks 13 are laminated in the axial direction while being displaced at 90 deg. in succession.
展开▼
