Magnet arrangement for axial flux focussing for two-pole permanent magnet A.C. machines

Claim 1

A two-pole permanent magnet A.C. machine comprising: a stator; a rotor, rotatable relative to said stator about a longitudinal axis thereof, and separated from said stator by a circumferential air-gap; said rotor comprising: a plurality of disc-shaped permanent magnets oriented such that the axis of magnetization of each of said permanent magnets is parallel to the axis of rotation of said rotor; said disc-shaped permanent magnets being disposed concentrically about said axis and in axially spaced relationship; a plurality of annular spacers of nonmagnetic material surrounding, respectively, each of said permanent magnets; a plurality of magnetic flux collectors interleaved with said plurality of discshaped permanent magnets; alternate ones of said flux collectors having arcuate projections extending radially outward to form a pole of said rotor and the others of said flux collectors having arcuate projections extending radially outward to form the other pole of said rotor, said poles being centered 180° apart; a plurality of arcuate permanent magnets disposed in axial alignment with and radially adjacent respective ones of said flux collectors and diametrically opposite said respective projections; and a retaining ring surrounding said annular spacers, said projections of said flux collectors and said arcuate permanent magnets; said retaining ring comprising alternate arcuate segments of magnetic and nonmagnetic material bonded into a unitary retaining ring.