| 摘要 |
PROBLEM TO BE SOLVED: To provide a ring-shaped permanent magnet wherewith the cogging and fluctuation in the output torque of a motor are easily reduced even if the magnetic characteristics fluctuate depending on the position in the cylindrical magnet body in the axial direction and a permanent magnet motor, using the permanent magnet. SOLUTION: The ring-shaped permanent magnet 1 comprises the magnet body 2 which is in a cylindrical shape as a whole and a plurality of north poles and south poles alternately magnetized on the circumferential surface 4 of the magnet body 2 in the circumferential direction. The north poles and the south poles are magnetized in such a pattern that the poles are provided with steep inclinations 7 in the direction of the axis of the magnet body 2 at the portions close to the lower end face 5b of the magnet body 2 where the magnetic characteristics are high and with gentle inclinations 6 in the direction of the axis of the magnet body 2 at the portions close to the upper end face 5a and the middle portion of the magnet body 2 where the magnetic characteristics are low. COPYRIGHT: (C)2003,JPO
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