Patent ID: 8987965
Filing Date: 2015-03-24
Classification: H02K

Abstract:
1. A permanent magnet rotating machine comprising: a rotor comprising one or more Nd-based rare earth sintered permanent magnets in each of two or more insertion holes, the insertion holes being formed in a circumferential direction in a rotor core; and a stator disposed with a clearance from an outer peripheral face of the rotor and formed by winding a winding wire through a stator core having two or more slots, wherein a magnetic coercive force in a stator-side surface region of each of the Nd-based rare earth sintered permanent magnets is greater than that in an inner central portion by 300 kA/m or more, the inner central portion being an inner portion at a depth of at least 5 mm from every outer face of the permanent magnet and wherein each of the Nd-based rare earth permanent magnets is prepared using heat treatment to diffuse Dy or Tb from a stator-side surface of a Nd-based rare earth sintered magnet body toward the inner central portion in order to distribute the magnetic coercive force, wherein the sintering temperature of the sintered magnet body is from 900° C. to 1,250° C.