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

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.degree. 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.