Patent ID: 7768158

Claim:
A cylindrical linear motor comprising: a stator; a movable element disposed via a clearance with respect to the stator, said movable element being adapted to move in a rectilinear moving direction with respect to said stator; wherein: said stator includes a stator core having stator salient poles and includes a three-phase stator coil winding inserted within a slot formed in said stator core, said movable element includes a plurality of ring-shaped permanent magnets fixed to a movable element core, and said stator salient poles are pitched at τs and said permanent magnets are pitched at τp to establish a relationship of 3/4<τp/τs<3/2; and a plurality of hollow portions formed on said movable element core along an axis of a movable element moving direction at a predetermined interval; wherein said permanent magnets are provided at said plurality of hollow portions formed on said movable element core, respectively; each of said permanent magnets is comprised of a plurality of said divided permanent magnets, and is magnetized in a radial direction relative to the ring so as to have reverse polarity along the movable element moving direction; wherein each coil winding of said three-phase stator coil winding has a plurality of coil windings, and stator coils are wound in the same direction.