JPS645348A - Permanent magnet rotor for stepping motor - Google Patents

Abstract

PURPOSE:To improve rotating torque, by jointing a pole plate smaller in width than the magnetized zone to the magnetized part on the outside circumference of a permanent magnet. CONSTITUTION:Most of the flux swelled outside a permanent magnet 1 goes through a pole plate 5 of high permeability. That is, the flux gathers to the pole plate 5 narrower than the magnetized zone of the permanent magnet 1. As a result, reactive flux extremely close to the surface of the permanent magnet 1 is reduced which connects the edges of the magnetized zone of an N pole and an S pole. Most of the flux will be badly swelled out to outside the permanent magnet 1, covering a stator, though unillustrated. In this way, since the strip pole plate 5 narrower in width than its magnetized zone is jointed to the magnetized section of the S pole and N pole on the outside circumference of the cylindrical permanent magnet 1, the flux caused by the pole plate 5 from the magnetized zone is gathered to the center part and swelled outward and the reactive flux is thereby reduced and the rotating torque of the motor improved.