Patent ID: 9705365
Date: 2017-07-11
CPC Classifications: H02K

Claim:
1. A motor comprising: a stator having a stator core and a winding; a rotor having a first rotor core, a second rotor core, and a field magnet, each of the first and second rotor cores having a substantially disc-shaped core base and a plurality of claw-shaped magnetic poles provided on an outer peripheral portion of the core base along a peripheral direction, the field magnet being sandwiched between the first rotor core and the second rotor core in an axial direction, and the field magnet being configured such that the claw-shaped magnetic pole of the first rotor core and the claw-shaped magnetic pole of the second rotor core function as magnetic poles different from each other in a sandwiched state; a cylindrical case with a bottom, the case having a yoke housing that is a magnetic body and a lid portion closing an opening portion of the yoke housing, the yoke housing accommodating the stator and the rotor; and a plurality of back-surface magnet portions arranged in a gap formed on a back surface of the claw-shaped magnetic pole, wherein the plurality of back-surface magnet portions include a second back-surface magnet portion provided on the back surface of the claw-shaped magnetic pole of the second rotor core and a first back-surface magnet portion provided on the back surface of the claw-shaped magnetic pole of the first rotor core; and a size of the second back-surface magnet portion and a size of the first back-surface magnet portion are different from each other.