Electric motor having toothed pole pieces

摘要

An electric motor having a stator with a plurality of pole pieces which are disposed in angularly spaced intervals about the axis of rotation of a cooperating rotor. Each stator pole piece has one or more teeth thereon. Each tooth has an inner peripheral surface which lies on the circumference of a circle having its center on the axis of rotation of the rotor. The teeth on each stator pole piece (which has a plurality of teeth) are spaced with a uniform pitch therebetween and the pitch on one stator pole piece is the same as the pitch on any other stator pole piece. One of the stator pole pieces and an adjacent stator pole piece about the axis of the rotor comprise a pole pair. Each two successive stator pole pieces disposed about the axis of the rotor comprise additional pole pairs. The plurality of teeth on one of the stator pole pieces in each of the pole pairs is shifted with respect to the plurality of teeth on the other stator pole piece in the same pair one half of the tooth pitch and the plurality of teeth on the adjacent pole pieces of adjacent pairs of stator pole pieces are shifted 1/2N of a tooth pitch where N is the number of phases of the motor.