| 摘要 |
PURPOSE:To simplify a construction with a less number of part items, by means of installing a speed detecting coil in an auxiliary groove, utilized, provided in a protruding unit of armature core. CONSTITUTION:A rotor 1, having a permanent magnet 2 magnetized in a plurality of poles with an equal distance apart, an armature core 3, having a plurality of magnetic protrusion units 4a to 4c facing to the magnetized surfaces, a drive coil 5a to 5c installed to be wound on each of the protrusion units, and a speed detecting coil 7a to 7c, for obtaining a signal of frequency corresponding to a rotational speed of the rotor, are provided. An auxiliary groove 6a1 to 6c2 of the shape, that enlarges a space with the magnet, is provided in a part facing to a permanent magnet of the protrusion unit, with a speed detecting coil installed to be wound in said groove part. In this way, a magnetic surge component due to a groove 8a to 8c will be cancelled by a magnetic surge component of the auxiliary groove 6a1 to 6c2 and reduced capable of lessening a cogging force simulataneously with an initial requirement expectedly capable to be accomplished. |
