公开(公告)号：US09627933B2

公开(公告)日：2017-04-18

申请号：US14466392

申请日：2014-08-22

Applicant: Johnson Electric S.A.

Inventor： Mao Xiong Jiang ,  Yue Li ,  Tao Zhang ,  San Yuan Xiao ,  Lik Hon Chan

IPC: H02K1/27 ,  F04F5/16 ,  F04F5/46

CPC classification number: H02K1/278 ,  F04F5/16 ,  F04F5/46 ,  H02K2201/06 ,  Y10T137/2224

Abstract: A brushless motor includes a stator comprising a stator core with teeth protruding inwardly and windings wound on the teeth, and a rotor comprising a shaft, a rotor core fixed to the shaft, and a ring magnet fixed to the circumferential outer surface of the rotor core. The ring magnet includes a plurality of magnetic poles radially magnetized so that north poles and south poles are arranged alternately in the circumferential direction, boundary lines between adjacent magnetic poles being skewed by an angle α relative to an axis of the shaft. A plurality of grooves are formed in a circumferential outer surface of the rotor core. Each groove extends from one axial end to the other axial end of the rotor core, has a circumferential width smaller than each of the magnetic poles, and is covered by the ring magnet with a void formed between the groove and the ring magnet.