Patent ID: 7948135

Claim:
A permanent magnet motor using a permanent magnet which is multipolar magnetized in the peripheral direction, comprising: a stator having a plurality of teeth; and a radial anisotropic cylindrical magnet assembled in said motor so as to be combined with said stator; wherein said radial anisotropic cylindrical magnet comprises a portion magnetically oriented in directions tilted at an angle of 30° or more from radial directions, said portion being contained in said magnet at a volume ratio in a range of 2% or more and 50% or less; and a portion magnetically oriented in direction being radial directions or in directions tilted at an angle less than 30° from radial directions, said portion being the rest of the total volume of said magnet; said radial anisotropic cylindrical magnet comprises sintered magnet powder, said radial anisotropic cylindrical magnet being produced by preparing a metal mold having a core including, in at least part thereof, a ferromagnetic body having a saturated magnetic flux density of 5 kG or more, packing a magnet powder in a cavity of the metal mold, molding and sintering the magnet powder while applying an orientation magnetic field to the magnet powder by a horizontal-field vertical molding process; and said cylindrical magnet has 2n magnetized poles in the peripheral direction, where n is a positive integer in a range of 2 or more and 50 or less, said stator has 3m teeth to be combined with said cylindrical magnet, where m is a positive integer in a range of 2 or more and 33 or less, and the values 2n and 3m satisfy a relationship of 2n≠3m.