| 摘要 |
A linear motor is provided to reduce cogging torque sufficiently by defining a ratio W1/W as 0.43<W1/W<0.49. A linear motor includes a stator(1), a mover(3), an armature(9), and a permanent magnet magnetic pole row(15). The armature is arranged at one of the stator and the mover and has an iron core(5) and armature windings(7). The iron core has at least three permanent magnet magnetic pole units(5b) arranged in a moving direction of the mover. The armature windings are wound around the iron core to excite the permanent magnet magnetic pole units. The permanent magnet magnetic pole row is arranged at the other of the stator and the mover and has a base(11) and a plurality of permanent magnets(P1-P9). The base is made of magnetic material. The permanent magnets are arranged on the base at predetermined intervals in the moving direction of the mover so that N and S poles are alternately arranged. The permanent magnets face the permanent magnet magnetic pole units with a predetermined gap. A length W1, which is measured in a moving direction of each of the two permanent magnets arranged at both ends of the permanent magnet magnetic pole row, is smaller than a length W, which is measured in the moving direction of the remaining permanent magnets. The number of slots of each pole and each phase is 3/8. When a pitch between centers of the adjacent two magnetic pole units of the armature is defined as taus, the length W of the permanent magnet is defined as W=taus, and a ratio W1/W is defined as 0.43<W1/W<0.49.
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