Patent ID: 7019426
Filing Date: 2006-03-28
Classification: H02K

Abstract:
1. A brushless DC motor comprising: a rotor comprising a magnet; and a stator arranged with a plurality of slots at equal pitches in a circumferential direction; wherein a width in a diameter direction of a rib portion of the rotor does not exceed a value given by the following Equation: where, R: a rate of a leakage magnetic flux at a rib portion to a magnetic flux progressing from the magnet to the stator Wm: an effective magnetic pole width in circumferential direction Bz: a saturation magnetic flux density of a magnetic member of the rotor Bm: a magnetic flux density of the rib portion of the rotor in a radial direction of the rotor Lr: a length in the circumferential direction of the rib portion.