Patent ID: 7202585

Claim:
A brushless motor comprising: a stator having a core with slots formed therein and coils disposed in said slots, respectively, of said core; and a rotor having a plurality of segment type magnets disposed inside said stator so as to face said stator; wherein said magnets are magnetized in reverse radial orientation with respect to said rotor in such a manner that magnetic fields directed toward said stator converge toward said stator, and each of said magnets is provided at opposite ends of an outer peripheral surface of said magnets with a pair of notched portions so that a width of said magnets in a radial direction of said rotor gradually decreases toward said opposite end; and wherein an area of each of said pair of notched portions is expressed as follows: S =( D 2 /P )×α where D is the diametral dimension of said intermediate portion of said outer peripheral surface of each of said magnets; P is the number of pole pairs; and α is a shape factor and is in the range of 0<α≦0.012.