Composite magnet brushless DC motor

Abstract

The brushless DC motor comprises at least one multi-pole composite magnet which functions as a rotor, at least one stator member which determines the angular position of this rotor, means for positioning the rotor(s) and the stator member(s) on a common axis, a sensing device for determining the position of the composite magnet relative to the stator member(s), and means for determining the magnetic configuration on the stator member. The composite magnet comprises two sections, each section having a plurality of projections and apertures. The projections and apertures on a first section mate with the apertures and projections, respectively, on the second section. The first and second sections are magnetized in opposite axial directions. In one embodiment, each stator member has a plurality of pole pieces which are positioned in operative relation to the composite magnet. Two windings are formed on each stator member. Applying current to one or the other of these windings determines the polarity of the pole pieces on that stator member. In another embodiment, the two windings are positioned into sectors by protrusions on the outer rim of the stator member.

Dependencies are inferred from the claim text.