Patent ID: 7884520

Claim:
A brushless motor comprising: a tubular stator case; a stator core fitted into the stator case; and a rotor rotatably supported via a bearing inside the stator core, wherein the stator core includes a tubular yoke portion and six split cores which are detachably mounted on the yoke portion; six commutating-pole teeth, which extend radially inward, are integrally formed on an inner peripheral surface of the yoke portion at regular intervals in a peripheral direction of the yoke portion; each commutating-pole tooth of the six commutating-pole teeth has a straight walled portion having a constant width and a root portion having a gradually increasing width formed by inclined shoulders which gradually enlarge in a radially outward direction, the radial length of the root portion is larger than the radial length of the straight walled portion, and faces of the shoulders of mutually adjacent commutating-pole teeth face each other so as to be parallel to each other.