High efficiency permanent magnet machine with separated tab pole rotor and stacked ceramic magnet sections
A permanent magnet motor, generator or the like that uses ceramic magnets in the rotor to concentrate the magnetic flux in the airgap. Poles are formed by pole plates with integral tabs forming north and south poles with magnetic separators therebetween. Magnet sections are stacked axially.
1. A rotary electric machine with the rotor comprising at least one permanent magnet section with a magnet of magnetically hard material disposed between similar axially spaced pole plates made from magnetically soft material, said magnet having the majority of its interior portion generally shaped to conform to the shape of said pole plates, a plurality of circumaxially spaced peripherally outwardly exposed tabs of soft magnetic material serving to direct flux into circumaxially alternating north and south poles around the periphery of the magnet section, and a plurality of separators of hard magnetic material respectively disposed between said tabs.
2. A rotary electric machine as set forth in claim 1 wherein the tabs are formed integrally with and as extensions from the pole plates.
3. A rotary electric machine as set forth in claim 1 wherein the interior section of the magnet is shaped to be thicker in the center and thinner around the periphery.
4. A rotary electric machine as set forth in claim 1 wherein the magnet section has a through opening at its axis.
5. A rotary electric machine as set forth in claim 1 wherein there are two or more similar magnet sections provided in axially stacked relationship, and wherein the tabs on each magnet sections are arranged for axial alignment with the tabs on axially adjacent magnet sections.
6. A rotary electric machine as set forth in claim 1 wherein the tabs have a non-uniform cross section that is generally smaller in cross section in progression away from the magnetically soft material.
7. A rotary electric machine as set forth in claim 1 wherein the hard magnetic material separators between tabs are formed integrally with the magnet.
8. A rotary electric machine as set forth in claim 1 wherein there is an attachment means located on each of the pole plates.
9. A rotary electric machine as set forth in claim 8 wherein said attachment means is located centrally on each pole plate with respect to at least one of the tabs on said pole plate.
10. A rotary electric machine as set forth in claim 1 wherein the magnet comprises a ceramic ferrite material.
11. A rotary electric machine as set forth in claim 1 wherein the magnet section is surrounded by a structural retaining band.
12. A rotary electric machine rotating as set forth in claim 11 wherein there is a gap filling material inserted between the band and magnet section.
13. A rotary electric machine as set forth in claim 11 wherein the band is made of stainless steel.
14. A rotary electric machine as set forth in claim 1 wherein the pole plates are made of low carbon steel.
15. A rotary electric machine as set forth in claim 1 wherein the pole plates are of cast construction.
16. A rotary electric machine as set forth in claim 15 wherein the pole plates are cast over a preformed magnet.
17. A rotary electric machine as set forth in claim 1 wherein the rotor is internal to the stators.
18. A rotary electric machine as set forth in claim 17 wherein the rotor has a central through opening, and wherein a shaft is provided and is entered in said opening in press fit engagement with the rotor.