Patent ID: 7294944
Filing Date: 2007-11-13
Classification: H02K

Abstract:
1. A brushless motor having a rotational axis comprising: a cover for covering an outer part of the motor, the cover having a cover cylindrical portion with a bottom surface downward and with a open end upward; a housing having a housing cylindrical portion, the housing connected fixedly with a central portion of the bottom surface of the cover and the housing cylindrical portion located at a rotationally symmetric location around the rotational axis; a bearing fixed to an inner peripheral surface of the housing cylindrical portion; a rotary shaft rotatably supported by the bearing about the rotational axis; a rotor yoke located at an upper part of the housing, the rotor yoke having a rotary shaft connecting portion connected fixedly with an outer surface of the rotary shaft, a roof surface portion connected integrally with an upper end of the rotary shaft connecting portion and extending radially outward, and a yoke cylindrical portion connected integrally with a radially outer end of the roof surface portion and extending axially downward for covering the housing; a main magnet fixed on an outer peripheral surface of the yoke cylindrical portion; a stator fixed on an inner peripheral surface of the cover cylindrical portion and an inner surface of the stator confronting an outer peripheral surface of the main magnet with a gap; a circuit board located at an upper part of the cover, wherein an outer end of the circuit board is fixed to an upper end part of the cover; and a position sensor mounted on the circuit board for detecting the rotational position of the rotor; wherein the rotary shaft, the bearing, the housing cylindrical portion, the yoke cylindrical portion, the main magnet, the stator and the cover cylindrical portion are arranged in order radially outward from the rotary shaft to the cover.