Patent ID: 7345393

Claim:
A cored motor comprising: a rotor having a rotor hub, a shaft fixed to the rotor hub, a rotor yoke having a ring shape and a ring magnet fixed to an inner circumferential surface of the rotor yoke; and a stator being composed of a motor base, and a stator core and a sleeve of cylindrical shape fixed to the motor base respectively, wherein the shaft is inserted into the sleeve so as to support the rotor to be rotatable freely with respect to the stator while the ring magnet is kept confronting the stator core; wherein a surface of the rotor hub in the motor base side is provided with a recessed portion of annular shape and a raised portion selectively protruding continuously or intermittently in an annular shape; wherein the rotor yoke is fixed to the recessed portion; wherein the ring magnet contacts the raised portion and is fixed to the rotor yoke; wherein respective center lines of the rotor yoke, the ring magnet and the stator core in a longitudinal direction along the shaft are made approximately coincidental with each other; wherein the rotor yoke, the ring magnet and the stator core are symmetrical with respect to a plane that intersects the shaft at right angles and includes their respective center lines; wherein a shape of the rotor yoke is symmetrical with respect to the plane; and further wherein a magnetic center of the ring magnet is made coincidental with the plane.