To protect a permanent magnet against damage even if an external force is applied to the inner circumferential surface thereof when a motor housing fixed with permanent magnets is handled in an electric motor where a pair of minor arcuate permanent magnets composed of neodymium bond magnet are arranged along the inner circumferential surface of a tubular motor housing, a set spring is provided while being compressed between the opposing end faces of one of the pair of permanent magnets, and the pair of permanent magnets are pressure held on the inner circumferential surface of the motor housing.
Radius r of the outer circumferential surface of a permanent magnet 5 is set smaller than the radius R of the inner circumferential surface of a motor housing 4 so that the circumferential central part of the permanent magnet 5 abuts against the inner circumferential surface of the motor housing 4 and its opposite circumferential ends float from the inner circumferential surface of the motor housing 4. When an external force acts on the inner surface at one circumferential end of the permanent magnet 5, 5, the permanent magnet is not damaged but simply oscillates.
FUKUDA MITSURU
INOMATA KOICHI
SENGOKU KOJI
TSUDA YUKITAKA
NAKAYAMA SATOSHI
Kazuaki Niki