| 摘要 |
PROBLEM TO BE SOLVED: To suppress reduction in motor efficiency due to overcurrent by forming a plurality of slits in at least one face out of the whole surface of a rare earth sintered magnet. SOLUTION: Fine slits are formed in a face of a rare earth sintered magnet where overcurrent is mainly generated, that is, in an armature-side face of the magnet, to reduce an effective area where overcurrent is generated. Roughly speaking, slits which are sufficiently deeper than the skin depth of overcurrent are formed on the surface of the magnet. The width of each slit should be narrow, 1 mm or below, to reduce an effect of disturbing the magnetic flux distribution. The depth of each slit is 0.5 mm or above and at most one third the thickness of the magnet in the slit direction. By filling the slits with the non-conductive material such as an adhesive and resin, the reduction in mechanical strength can be compensated for. By this, the reduction in anti-bending force caused by formation of the slits can be compensated for while securing an effect of reducing overcurrent. Due to this structure, a permanent magnet type synchronous motor with a high general versatility can be obtained by a simple process.
|
