Permanent magnet assembly

• US 7,148,777 B2
• Filed: 02/03/2005
• Issued: 12/12/2006
• Est. Priority Date: 02/03/2004
• Status: Active Grant

• Current Assignee: Astronautics Corporation of America
• Original Assignee: Astronautics Corporation of America
• Inventors: Zimm, Carl B., Chell, Jeremy
• Primary Examiner(s): DONOVAN, LINCOLN D
• Application Number:
  US11/050,109
• Publication Number:
  US 20050242912A1
• Time in Patent Office: 677 Days
• Field of Search: 335302-306
• US Class Current: 335/306
• CPC Class Codes: F25B 21/00 Machines, plants or systems, using electric or magnetic effects
• CPC Class Codes: F25B 2321/0021 with a static fixed magnet
• CPC Class Codes: F25B 2321/0023 with modulation, influencing or enhancing an existing magnetic field
• CPC Class Codes: H01F 7/0205 Magnetic circuits with PM in general
• CPC Class Codes: Y02B 30/00 Energy efficient heating, ventilation or air conditioning [HVAC]

Abstract

A permanent magnet assembly is disclosed that is adapted to provide a magnetic field across an arc-shaped gap. Such a permanent magnet assembly can be used, for example, to provide a time-varying magnetic field to an annular region for use in a magnetic refrigerator.

Claims

1. A permanent magnet assembly comprising:

a first upper radial permanent magnet and a second upper radial permanent magnet;

each upper radial permanent magnet formed as a polyhedral solid having six or more essentially planar faces comprising an upper face substantially parallel to and opposite a lower face, an inside lateral face opposite an outside lateral face, and an inside radial face substantially parallel to and opposite an outside radial face, wherein its upper and lower faces are substantially orthogonal to its inside and outside radial faces;

each upper radial permanent magnet having a magnetization vector wherein its inside radial face is a flux exit face, its outside radial face is a flux entry face, and its upper and lower faces are flux parallel faces;

and wherein the inside lateral face of the first upper radial permanent magnet is fastened to the inside lateral face of the second upper radial permanent magnet;

a first lower radial permanent magnet and a second lower radial permanent magnet,

each central lower radial permanent magnet formed as a polyhedral solid having six or more essentially planar faces comprising an upper face substantially parallel to and opposite a lower face, an inside lateral face opposite an outside lateral face, and an inside radial face substantially parallel to and opposite an outside radial face, wherein its upper and lower faces are substantially orthogonal to its inside and outside radial faces;

each lower radial permanent magnet having a magnetization vector wherein its inside radial face is a flux entry face, its outside radial face is a flux exit face, and its upper and lower faces are flux parallel faces;

and wherein the inside lateral face of the first lower radial permanent magnet is fastened to the inside lateral face of the second lower radial permanent magnet;

a first central axial permanent magnet and a second central axial permanent magnet;

each central axial permanent magnet formed as a polyhedral solid having six or more essentially planar faces comprising an upper face substantially parallel to and opposite a lower face, an inside lateral face opposite an outside lateral face, and an inside radial face substantially parallel to and opposite an outside radial face, wherein its upper and lower faces are substantially orthogonal to its inside and outside radial faces;

each central axial permanent magnet having a magnetization vector wherein its inside radial face and outside radial face are flux parallel faces, its upper face is a flux exit face, and its lower face is a flux entry face;

wherein the inside lateral face of the first central axial permanent magnet is fastened to the inside lateral face of the second central axial permanent magnet;

wherein the upper face of the first central axial permanent magnet is magnetically coupled to the lower face of the first upper radial permanent magnet;

wherein the lower face of the first central axial permanent magnet is magnetically coupled to the upper face of the first lower radial permanent magnet;

wherein the upper face of the second central axial permanent magnet is magnetically coupled to the lower face of the second upper radial permanent magnet;

and wherein the lower face of the second central axial permanent magnet is magnetically coupled to the upper face of the second lower radial permanent magnet;

a first upper axial permanent magnet and a second upper axial permanent magnet;

each upper axial permanent magnet formed as a polyhedral solid having six or more essentially planar faces comprising an upper face substantially parallel to and opposite a lower face, an inside lateral face opposite an outside lateral face, and an inside radial face substantially parallel to and opposite an outside radial face, wherein its upper and lower faces are substantially orthogonal to its inside and outside radial faces;

each upper axial permanent magnet having a magnetization vector wherein its inside radial face and outside radial face are flux parallel faces, its upper face is a flux entry face, and its lower face is a flux exit face;

wherein the inside lateral face of the first upper axial permanent magnet is fastened to the inside lateral face of the second upper axial permanent magnet;

wherein the inside radial face of the first upper radial permanent magnet is magnetically coupled to the outside radial face of the first upper axial permanent magnet;

wherein the inside radial face of the second upper radial permanent magnet is magnetically coupled to the outside radial face of the second upper axial permanent magnet;

a first lower axial permanent magnet and a second lower axial permanent magnet;

each lower axial permanent magnet formed as a polyhedral solid having six or more essentially planar faces comprising an upper face substantially parallel to and opposite a lower face, an inside lateral face opposite an outside lateral face, and an inside radial face substantially parallel to and opposite an outside radial face, wherein its upper and lower faces are substantially orthogonal to its inside and outside radial faces;

each lower axial permanent magnet having a magnetization vector wherein its inside radial face and outside radial face are flux parallel faces, its upper face is a flux entry face, and its lower face is a flux exit face;

wherein the inside lateral face of the first lower axial permanent magnet is fastened to the inside lateral face of the second lower axial permanent magnet;

wherein the inside radial face of the first lower radial permanent magnet is magnetically coupled to the outside radial face of the first lower axial permanent magnet;

wherein the inside radial face of the second lower radial permanent magnet is magnetically coupled to the outside radial face of the second lower axial permanent magnet;

whereby a first gap experiencing a high magnetic field is formed between at least a portion of the lower face of the first upper axial permanent magnet and at least a portion of the upper face of the first lower axial permanent magnet, and a second gap experiencing a high magnetic field is formed between at least a portion of the lower face of the second upper axial permanent magnet and at least a portion of the upper face of the second lower axial permanent magnet.

2. The permanent magnet assembly of claim 1, further comprising:

a first upper radial blocking permanent magnet and a second upper radial blocking permanent magnet;

each upper radial blocking permanent magnet formed as a polyhedral solid having six or more essentially planar faces comprising an upper face substantially parallel to and opposite a lower face, an inside lateral face opposite an outside lateral face, and an inside radial face substantially parallel to and opposite an outside radial face, wherein its upper and lower faces are substantially orthogonal to its inside and outside radial faces;

each upper radial blocking permanent magnet having a magnetization vector wherein its inside radial face is a flux entry face, its outside radial face is a flux exit face, and its upper and lower faces are flux parallel faces;

and wherein the inside lateral face of the first upper radial blocking permanent magnet is fastened to the inside lateral face of the second upper radial blocking permanent magnet;

a first lower radial blocking permanent magnet and a second lower radial blocking permanent magnet;

each lower radial blocking permanent magnet formed as a polyhedral solid having six or more essentially planar faces comprising an upper face substantially parallel to and opposite a lower face, an inside lateral face opposite an outside lateral face, and an inside radial face substantially parallel to and opposite an outside radial face, wherein its upper and lower faces are substantially orthogonal to its inside and outside radial faces;

each lower radial blocking permanent magnet having a magnetization vector wherein its inside radial face is a flux exit face, its outside radial face is a flux entry face, and its upper and lower faces are flux parallel faces;

and wherein the inside lateral face of the first lower radial blocking permanent magnet is fastened to the inside lateral face of the second lower radial blocking permanent magnet;

wherein the outside radial face of the first upper radial blocking permanent magnet is magnetically coupled to the inside radial face of the first upper axial permanent magnet;

wherein the outside radial face of the second upper radial blocking permanent magnet is magnetically coupled to the inside radial face of the second upper axial permanent magnet;

wherein the outside radial face of the first lower radial blocking permanent magnet is magnetically coupled to the inside radial face of the first lower axial permanent magnet; and

wherein the outside radial face of the second lower radial blocking permanent magnet is magnetically coupled to the inside radial face of the second lower axial permanent magnet.

3. The permanent magnet assembly of claim 2, further comprising:

a first upper circumferential blocking permanent magnet, a second upper circumferential blocking permanent magnet, a first lower circumferential blocking permanent magnet, and a second lower circumferential blocking permanent magnet;

each circumferential blocking permanent magnet formed as a polyhedral solid having six or more essentially planar faces comprising an upper face opposite a lower face, an inside lateral face opposite an outside lateral face, and an inside radial face opposite an outside radial face;

the first upper circumferential blocking permanent magnet having a magnetization vector wherein its outside lateral face is a flux entry face, its inside lateral face is a flux exit face, and its upper and lower faces are flux parallel faces and wherein the inside lateral face of the first upper circumferential blocking permanent magnet is magnetically coupled to the outside lateral face of the first upper radial magnet and magnetically coupled to the outside lateral face of the first upper axial magnet;

the second upper circumferential blocking permanent magnet having a magnetization vector wherein its outside lateral face is a flux entry face, its inside lateral face is a flux exit face, and its upper and lower faces are flux parallel faces and wherein the inside lateral face of the second upper circumferential blocking permanent magnet is magnetically coupled to the outside lateral face of the second upper radial magnet and magnetically coupled to the outside lateral face of the second upper axial magnet;

the first lower circumferential blocking permanent magnet having a magnetization vector wherein its outside lateral face is a flux exit face, its inside lateral face is a flux entry face, and its upper and lower faces are flux parallel faces and wherein the inside lateral face of the first lower circumferential blocking permanent magnet is magnetically coupled to the outside lateral face of the first lower radial magnet and magnetically coupled to the outside lateral face of the first lower axial magnet; and

the second lower circumferential blocking permanent magnet having a magnetization vector wherein its outside lateral face is a flux exit face, its inside lateral face is a flux entry face, and its upper and lower faces are flux parallel faces and wherein the inside lateral face of the second lower circumferential blocking permanent magnet is magnetically coupled to the outside lateral face of the second lower radial magnet and magnetically coupled to the outside lateral face of the second lower axial magnet.

4. The permanent magnet assembly of claim 1, further comprising:

a first upper circumferential blocking permanent magnet, a second upper circumferential blocking permanent magnet, a first lower circumferential blocking permanent magnet, and a second lower circumferential blocking permanent magnet;

each circumferential blocking permanent magnet formed as a polyhedral solid having six or more essentially planar faces comprising an upper face opposite a lower face, an inside lateral face opposite an outside lateral face, and an inside radial face opposite an outside radial face;

the first upper circumferential blocking permanent magnet having a magnetization vector wherein its outside lateral face is a flux entry face, its inside lateral face is a flux exit face, and its upper and lower faces are flux parallel faces and wherein the inside lateral face of the first upper circumferential blocking permanent magnet is magnetically coupled to the outside lateral face of the first upper radial magnet and magnetically coupled to the outside lateral face of the first upper axial magnet;

the second upper circumferential blocking permanent magnet having a magnetization vector wherein its outside lateral face is a flux entry face, its inside lateral face is a flux exit face, and its upper and lower faces are flux parallel faces and wherein the inside lateral face of the second upper circumferential blocking permanent magnet is magnetically coupled to the outside lateral face of the second upper radial magnet and magnetically coupled to the outside lateral face of the second upper axial magnet;

the first lower circumferential blocking permanent magnet having a magnetization vector wherein its outside lateral face is a flux exit face, its inside lateral face is a flux entry face, and its upper and lower faces are flux parallel faces and wherein the inside lateral face of the first lower circumferential blocking permanent magnet is magnetically coupled to the outside lateral face of the first lower radial magnet and magnetically coupled to the outside lateral face of the first lower axial magnet; and

the second lower circumferential blocking permanent magnet having a magnetization vector wherein its outside lateral face is a flux exit face, its inside lateral face is a flux entry face, and its upper and lower faces are flux parallel faces and wherein the inside lateral face of the second lower circumferential blocking permanent magnet is magnetically coupled to the outside lateral face of the second lower radial magnet and magnetically coupled to the outside lateral face of the second lower axial magnet.

5. The permanent magnet assembly of claim 1, wherein the first upper radial permanent magnet assembly, the second upper radial permanent magnet assembly, the first central axial permanent magnet assembly, the second central axial permanent magnet assembly, the first lower radial permanent magnet assembly, and the second lower radial permanent magnet assembly each have six essentially planar faces.

6. A permanent magnet assembly comprising:

an upper radial permanent magnet formed as an arc-shaped solid having six or more faces comprising a substantially planar upper face substantially parallel to and opposite a substantially planar lower face, a concave curved inside radial face opposite a convex curved outside radial face, and first and second circumferential end faces;

the upper radial permanent magnet having a magnetization vector wherein its inside radial face is a flux exit face, its outside radial face is a flux entry face, and its upper and lower faces are flux parallel faces;

a lower radial permanent magnet formed as an arc-shaped solid having six or more faces comprising a substantially planar upper face substantially parallel to and opposite a substantially planar lower face, a concave curved inside radial face opposite a convex curved outside radial face, and first and second circumferential end faces;

the lower radial permanent magnet having a magnetization vector wherein its inside radial face is a flux entry face, its outside radial face is a flux exit face, and its upper and lower faces are flux parallel faces;

a central axial permanent magnet formed as an arc-shaped solid having six or more faces comprising a substantially planar upper face substantially parallel to and opposite a substantially planar lower face, a concave curved inside radial face opposite a convex curved outside radial face, and first and second circumferential end faces;

the central axial permanent magnet having a magnetization vector wherein its inside radial face and outside radial face are flux parallel faces, its upper face is a flux exit face, and its lower face is a flux entry face;

wherein the upper face of the lower radial permanent magnet is magnetically coupled to the lower face of the central axial permanent magnet;

wherein the lower face of the upper radial permanent magnet is magnetically coupled to the upper face of the central axial permanent magnet;

an upper axial permanent magnet formed as an arc-shaped solid having six or more faces comprising a substantially planar upper face substantially parallel to and opposite a substantially planar lower face, a concave curved inside radial face opposite a convex curved outside radial face, and first and second circumferential end faces;

the upper axial permanent magnet having a magnetization vector wherein its inside radial face and its outside radial face are flux parallel faces, its upper face is a flux entry face and its lower face is a flux exit face;

wherein the inside radial face of the upper radial permanent magnet is magnetically coupled to the outside radial face of the upper axial permanent magnet; and

a lower axial permanent magnet formed as an arc-shaped solid having six or more faces comprising a substantially planar upper face substantially parallel to and opposite a substantially planar lower face, a concave curved inside radial face opposite a convex curved outside radial face, and first and second circumferential end faces;

the lower axial permanent magnet having a magnetization vector wherein its inside radial face and its outside radial face are flux parallel faces, its upper face is a flux entry face and its lower face is a flux exit face;

wherein the inside radial face of the lower radial permanent magnet is magnetically coupled to the outside radial face of the lower axial permanent magnet;

whereby an arc-shaped gap experiencing a high magnetic field is formed between at least a portion of the lower face of the upper axial permanent magnet and at least a portion of the upper face of the lower axial permanent magnet.

7. The permanent magnet assembly of claim 6, further comprising:

an exterior sheath formed as an arc-shaped solid of magnetically permeable material having a concave curved inside radial face that is magnetically coupled to at least a portion of the outside radial face of the upper radial permanent magnet, at least a portion of the outside radial face of the central axial permanent magnet, and at least a portion of the outside radial face of the lower radial permanent magnet.

8. The permanent magnet assembly of claim 7, further comprising:

an upper sheath formed as an arc-shaped solid of magnetically permeable material having a substantially planar bottom face that is magnetically coupled to at least a portion of the upper face of the upper radial permanent magnet and at least a portion of the upper face of the upper axial permanent magnet; and

a lower sheath formed as an arc-shaped solid of magnetically permeable material having a substantially planar upper face that is magnetically coupled to at least a portion of the lower face of the lower radial permanent magnet and at least a portion of the lower face of the lower axial permanent magnet.

9. The permanent magnet assembly of claim 8, further comprising:

an upper pole piece formed as an arc-shaped solid of magnetically permeable material having a substantially planar upper face that is magnetically coupled to at least a portion of the lower face of the upper axial permanent magnet; and

a lower pole piece formed as an arc-shaped solid of magnetically permeable material having a substantially planar lower face that is magnetically coupled to at least a portion of the upper face of the lower axial permanent magnet.

10. The permanent magnet assembly of claim 6, further comprising:

an upper sheath formed as an arc-shaped solid of magnetically permeable material having a substantially planar bottom face that is magnetically coupled to at least a portion of the upper face of the upper radial permanent magnet and at least a portion of the upper face of the upper axial permanent magnet; and

a lower sheath formed as an arc-shaped solid of magnetically permeable material having a substantially planar upper face that is magnetically coupled to at least a portion of the lower face of the lower radial permanent magnet and at least a portion of the lower face of the lower axial permanent magnet.

11. A permanent magnet assembly comprising:

a first upper radial permanent magnet and a second upper radial permanent magnet;

each upper radial permanent magnet formed as a rectangular block having six or more essentially planar faces comprising an upper face substantially parallel to and opposite a lower face, a first lateral face opposite a second lateral face, and an inside radial face substantially parallel to and opposite an outside radial face, wherein its upper and lower faces, its inside and outside radial faces, and its first and second lateral faces are substantially orthogonal;

each upper radial permanent magnet having a magnetization vector wherein its inside radial face is a flux entry face, its outside radial face is a flux exit face, its first and second lateral faces are flux parallel faces, and its upper and lower faces are flux parallel faces;

and wherein the inside radial face of the first upper radial permanent magnet is joined to the inside radial face of the second upper radial permanent magnet by a slab of magnetically permeable material;

a first upper axial permanent magnet and a second upper axial permanent magnet;

each upper axial permanent magnet formed as a rectangular block having six or more essentially planar faces comprising an upper face substantially parallel to and opposite a lower face, a first lateral face opposite a second lateral face, and an inside radial face substantially parallel to and opposite an outside radial face, wherein its upper and lower faces, its first and second lateral faces, and its inside and outside radial faces are substantially orthogonal;

each upper axial permanent magnet having a magnetization vector wherein its upper face is a flux entry face, its lower face is a flux exit face, its first and second lateral faces are flux parallel faces, and its inside and outside radial faces are flux parallel faces;

wherein the inside radial face of the first upper axial permanent magnet is magnetically coupled to the outside radial face of the first upper radial permanent magnet;

wherein the inside radial face of the second upper axial permanent magnet is magnetically coupled to the outside radial face of the second upper radial permanent magnet;

a first lower radial permanent magnet and a second lower radial permanent magnet;

each lower radial permanent magnet formed as a rectangular block having six or more essentially planar faces comprising an upper face substantially parallel to and opposite a lower face, a first lateral face opposite a second lateral face, and an inside radial face substantially parallel to and opposite an outside radial face, wherein its upper and lower faces, its inside and outside radial faces, and its first and second lateral faces are substantially orthogonal;

each lower radial permanent magnet having a magnetization vector wherein its inside radial face is a flux exit face, its outside radial face is a flux entry face, its first and second lateral faces are flux parallel faces, and its upper and lower faces are flux parallel faces;

and wherein the inside radial face of the first lower radial permanent magnet is joined to the inside radial face of the second lower radial permanent magnet by a slab of magnetically permeable material;

a first lower axial permanent magnet and a second lower axial permanent magnet;

each lower axial permanent magnet formed as a rectangular block having six or more essentially planar faces comprising an upper face substantially parallel to and opposite a lower face, a first lateral face opposite a second lateral face, and an inside radial face substantially parallel to and opposite an outside radial face, wherein its upper and lower faces, its first and second lateral faces, and its inside and outside radial faces are substantially orthogonal;

each lower axial permanent magnet having a magnetization vector wherein its upper face is a flux entry face, its lower face is a flux exit face, its first and second lateral faces are flux parallel faces, and its inside and outside radial faces are flux parallel faces;

wherein the inside radial face of the first lower axial permanent magnet is magnetically coupled to the outside radial face of the first lower radial permanent magnet;

wherein the inside radial face of the second lower axial permanent magnet is magnetically coupled to the outside radial face of the second lower radial permanent magnet;

a central axial permanent magnet formed as a solid having an upper face opposite a lower face;

the central axial permanent magnet having a magnetization vector wherein its upper face is a flux exit face and its lower face is a flux entry face;

wherein at least a portion of the upper face of the central axial permanent magnet is magnetically coupled to at least a portion of the lower face of the first upper radial permanent magnet and at least a portion of the lower face of the second upper radial permanent magnet;

wherein at least a portion of the lower face of the central axial permanent magnet is magnetically coupled to at least a portion of the upper face of the first lower radial permanent magnet and at least a portion of the upper face of the second lower radial permanent magnet;

whereby a first gap experiencing a high magnetic field is formed between at least a portion of the lower face of the first upper axial permanent magnet and at least a portion of the upper face of the first lower axial permanent magnet, and a second gap experiencing a high magnetic field is formed between at least a portion of the lower face of the second upper axial permanent magnet and at least a portion of the upper face of the second lower axial permanent magnet.

12. The permanent magnet assembly of claim 11, further comprising:

a first upper radial blocking permanent magnet, a second upper radial blocking permanent magnet, a first lower radial blocking permanent magnet, and a second lower radial blocking permanent magnet;

each radial blocking permanent magnet formed as a rectangular block having six or more essentially planar faces comprising an upper face substantially parallel to and opposite a lower face, a first lateral face substantially parallel to and opposite a second lateral face, and an inside radial face substantially parallel to and opposite an outside radial face, wherein its upper and lower faces, its first and second lateral faces, and its inside and outside radial faces are substantially orthogonal;

each upper radial blocking permanent magnet having a magnetization vector wherein its inside radial face is a flux exit face, its outside radial face is a flux entry face, its first and second lateral faces are flux parallel faces, and its upper and lower faces are flux parallel faces;

each lower radial blocking permanent magnet having a magnetization vector wherein its inside radial face is a flux entry face, its outside radial face is a flux exit face, its first and second lateral faces are flux parallel faces, and its upper and lower faces are flux parallel faces;

wherein the inside radial face of the first upper radial blocking permanent magnet is magnetically coupled to the outside radial face of the first upper axial permanent magnet;

wherein the inside radial face of the second upper radial blocking permanent magnet is magnetically coupled to the outside radial face of the second upper axial permanent magnet;

wherein the inside radial face of the first lower radial blocking permanent magnet is magnetically coupled to the outside radial face of the first lower axial permanent magnet; and

wherein the inside radial face of the second lower radial blocking permanent magnet is magnetically coupled to the outside radial face of the second lower axial permanent magnet.

13. The permanent magnet assembly of claim 11, further comprising:

a first upper lateral blocking permanent magnet, a second upper lateral blocking permanent magnet, a first lower lateral blocking permanent magnet, and a second lower lateral blocking permanent magnet;

each lateral blocking permanent magnet formed as a rectangular block having six or more essentially planar faces comprising an upper face substantially parallel to and opposite a lower face, a first lateral face substantially parallel to and opposite a second lateral face, and an inside radial face substantially parallel to and opposite an outside radial face, wherein its upper and lower faces, its first and second lateral faces, and its inside and outside radial faces are substantially orthogonal;

each upper lateral blocking permanent magnet having a magnetization vector wherein its inside radial face is a flux exit face, its outside radial face is a flux entry face, its first and second lateral faces are flux parallel faces, and its upper and lower faces are flux parallel faces;

each lower lateral blocking permanent magnet having a magnetization vector wherein its inside radial face is a flux entry face, its outside radial face is a flux exit face, its first and second lateral faces are flux parallel faces, and its upper and lower faces are flux parallel faces;

wherein the inside radial face of the first upper lateral blocking permanent magnet is magnetically coupled to at least a portion of the first lateral face of the first upper radial permanent magnet and at least a portion of the first lateral face of the second upper radial permanent magnet;

wherein the inside radial face of the second upper lateral blocking permanent magnet is magnetically coupled to at least a portion of the second lateral face of the first upper radial permanent magnet and at least a portion of the second lateral face of the second upper radial permanent magnet;

wherein the inside radial face of the first lower lateral blocking permanent magnet is magnetically coupled to at least a portion of the first lateral face of the first lower radial permanent magnet and at least a portion of the first lateral face of the second lower radial permanent magnet; and

wherein the inside radial face of the second lower lateral blocking permanent magnet is magnetically coupled to at least a portion of the second lateral face of the first lower radial permanent magnet and at least a portion of the second lateral face of the second lower radial permanent magnet.

14. The permanent magnet assembly of claim 11, further comprising:

an upper sheath formed as a solid of magnetically permeable material having a substantially planar bottom face that is magnetically coupled to at least a portion of the upper face of the first upper axial permanent magnet, at least a portion of the upper face of the first upper radial permanent magnet, at least a portion of the upper face of the second upper radial permanent magnet, and at least a portion of the upper face of the second upper axial permanent magnet; and

a lower sheath formed as a solid of magnetically permeable material having a substantially planar upper face that is magnetically coupled to at least a portion of the lower face of the first lower axial permanent magnet, at least a portion of the lower face of the first lower radial permanent magnet, at least a portion of the lower face of the second lower radial permanent magnet, and at least a portion of the lower face of the second lower axial permanent magnet.

15. The permanent magnet assembly of claim 11, further comprising:

a first upper pole piece formed as a solid of magnetically permeable material having a substantially planar upper face that is magnetically coupled to at least a portion of the lower face of the first upper axial permanent magnet;

a second upper pole piece formed as a solid of magnetically permeable material having a substantially planar upper face that is magnetically coupled to at least a portion of the lower face of the second upper axial permanent magnet;

a first lower pole piece formed as a solid of magnetically permeable material having a substantially planar lower face that is magnetically coupled to at least a portion of the upper face of the first lower axial permanent magnet; and

a second lower pole piece formed as a solid of magnetically permeable material having a substantially planar lower face that is magnetically coupled to at least a portion of the upper face of the second lower axial permanent magnet.

16. A permanent magnet assembly comprising:

an exterior axial permanent magnet formed as an arc-shaped solid having six or more faces comprising a substantially planar upper face substantially parallel to and opposite a substantially planar lower face, a concave curved inside radial face opposite a convex curved outside radial face, and first and second circumferential end faces;

the exterior axial permanent magnet having a magnetization vector wherein its upper face is a flux exit face, its lower face is a flux entry face, its inside and outside radial faces are flux parallel faces, and its first and second circumferential end faces are flux parallel faces;

an interior axial permanent magnet formed as an arc-shaped solid having six or more faces comprising a substantially planar upper face substantially parallel to and opposite a substantially planar lower face, a concave curved inside radial face opposite a convex curved outside radial face, and first and second circumferential end faces;

the interior axial permanent magnet having a magnetization vector wherein its upper face is a flux entry face, its lower face is a flux exit face, its inside and outside radial faces are flux parallel faces, and its first and second circumferential end faces are flux parallel faces;

a central radial permanent magnet formed as an arc-shaped solid having six or more faces comprising an upper face opposite a substantially planar lower face, a concave curved inside radial face opposite a convex curved outside radial face, and first and second circumferential end faces;

the central radial permanent magnet having a magnetization vector wherein its inside radial face is a flux entry face, its outside radial face is a flux exit face, its upper and lower faces are flux parallel faces, and its first and second circumferential end faces are flux parallel faces;

wherein the inside radial face of the exterior axial permanent magnet is magnetically coupled to the outside radial face of the central radial permanent magnet;

wherein the outside radial face of the interior axial permanent magnet is magnetically coupled to the inside radial face of the central radial permanent magnet;

an exterior radial permanent magnet formed as an arc-shaped solid having six or more faces comprising a substantially planar upper face substantially parallel to and opposite a substantially planar lower face, a concave curved inside radial face opposite a convex curved outside radial face, and first and second circumferential end faces;

the exterior radial permanent magnet having a magnetization vector wherein its upper and lower faces are flux parallel faces, its inside radial face is a flux exit face, its outside radial face is a flux entry face, and its first and second circumferential end faces are flux parallel faces;

wherein at least a portion of the lower face of the exterior radial permanent magnet is magnetically coupled to the upper face of the exterior axial permanent magnet;

an interior radial permanent magnet formed as an arc-shaped solid having six or more faces comprising a substantially planar upper face substantially parallel to and opposite a substantially planar lower face, a concave curved inside radial face opposite a convex curved outside radial face, and first and second circumferential end faces;

the interior radial permanent magnet having a magnetization vector wherein its upper and lower faces are flux parallel faces, its inside radial face is a flux exit face, its outside radial face is a flux entry face, and its first and second circumferential end faces are flux parallel faces;

wherein at least a portion of the lower face of the interior radial permanent magnet is magnetically coupled to the upper face of the interior axial permanent magnet;

whereby an arc-shaped gap experiencing a high magnetic field is formed between at least a portion of the inner radial face of the exterior radial permanent magnet and at least a portion of the outer radial face of the interior radial permanent magnet.

17. The permanent magnet assembly of claim 16, wherein the central radial permanent magnet has an interior chamfer between its inside radial face and its upper face, and an exterior chamfer between its outside radial face and its upper face.

18. The permanent magnet assembly of claim 16, further comprising:

an exterior sheath formed as a solid of magnetically permeable material having a concave inside radial face that is magnetically coupled to at least a portion of the outside radial face of the exterior radial permanent magnet and at least a portion of the outside radial face of the exterior axial permanent magnet;

a bottom sheath formed as a solid of magnetically permeable material having a substantially planar upper face that is magnetically coupled to at least a portion of the lower face of the interior axial permanent magnet, at least a portion of the lower face of the central radial permanent magnet, and at least a portion of the lower face of the exterior axial permanent magnet; and

an interior sheath formed as a solid of magnetically permeable material having a convex outside radial face that is magnetically coupled to at least a portion of the inside radial face of the interior radial permanent magnet and at least a portion of the inside radial face of the interior axial permanent magnet.

19. The permanent magnet assembly of claim 16, further comprising:

an interior pole piece formed as an arc-shaped solid of magnetically permeable material having a concave inside radial face that is magnetically coupled to at least a portion of the outside radial face of the interior radial permanent magnet; and

an exterior pole piece formed as an arc-shaped solid of magnetically permeable material having a convex outside radial face that is magnetically coupled to at least a portion of the inside radial face of the exterior radial permanent magnet.

20. The permanent magnet assembly of claim 19, wherein the central radial permanent magnet has an interior chamfer between its inside radial face and its upper face wherein the interior pole piece is magnetically coupled to the interior chamfer, and an exterior chamfer between its outside radial face and its upper face wherein the exterior pole piece is magnetically coupled to the exterior chamfer.

21. A permanent magnet assembly comprising:

a first upper major radial permanent magnet and a second upper major radial permanent magnet;

each upper major radial permanent magnet formed as a polyhedral solid having seven or more essentially planar faces comprising a five-sided upper face substantially parallel to and opposite a five-sided lower face, a first lateral face substantially parallel to and opposite a second lateral face, a first outside radial face and a second outside radial face opposite an inside radial face, wherein its upper and lower faces, its inside radial face, and its first and second lateral faces are substantially orthogonal;

each upper major radial permanent magnet having a magnetization vector wherein its inside radial face is at least a partial flux entry face, its outside radial faces are at least partial flux exit faces, its first and second lateral faces are flux parallel faces, and its upper and lower faces are flux parallel faces;

and wherein the inside radial face of the first upper major radial permanent magnet is joined to the inside radial face of the second upper major radial permanent magnet by a slab of magnetically permeable material;

a first upper axial permanent magnet and a second upper axial permanent magnet;

each upper axial permanent magnet formed as a polyhedral solid having eight or more essentially planar faces comprising an upper face substantially parallel to and opposite a lower face, a first inside radial face and a second inside radial face, a first lateral face opposite a second lateral face, and a first outside radial face and a second outside radial face,

each upper axial permanent magnet having a magnetization vector wherein its inside radial faces, its lateral faces, and its outside radial face are flux parallel faces, wherein the upper face is a flux entry face, and the lower face is a flux exit face;

wherein the first outside radial face of the first upper major radial permanent magnet is magnetically coupled to the first inside radial face of the first upper axial permanent magnet and the second outside radial face of the first upper major radial permanent magnet is magnetically coupled to the second inside radial face of the first upper axial permanent magnet;

wherein the first outside radial face of the second upper major radial permanent magnet is magnetically coupled to the first inside radial face of the second upper axial permanent magnet and the second outside radial face of the second upper major radial permanent magnet is magnetically coupled to the second inside radial face of the second upper axial permanent magnet;

a first lower major radial permanent magnet and a second lower major radial permanent magnet;

each lower major radial permanent magnet formed as a polyhedral solid having seven or more essentially planar faces comprising a five-sided upper face substantially parallel to and opposite a five-sided lower face, a first lateral face substantially parallel to and opposite a second lateral face, a first outside radial face and a second outside radial face opposite an inside radial face, wherein its upper and lower faces, its inside radial face, and its first and second lateral faces are substantially orthogonal;

each lower major radial permanent magnet having a magnetization vector wherein its inside radial face is at least a partial flux exit face, its outside radial faces are at least partial flux entry faces, its first and second lateral faces are flux parallel faces, and its upper and lower faces are flux parallel faces;

and wherein the inside radial face of the first lower major radial permanent magnet is joined to the inside radial face of the second lower major radial permanent magnet by a slab of magnetically permeable material;

a first lower axial permanent magnet and a second lower axial permanent magnet;

each lower axial permanent magnet formed as a polyhedral solid having eight or more essentially planar faces comprising an upper face substantially parallel to and opposite a lower face, a first inside radial face and a second inside radial face, a first lateral face opposite a second lateral face, and a first outside radial face and a second outside radial face,

each upper axial permanent magnet having a magnetization vector wherein its inside radial faces, its lateral faces, and its outside radial face are flux parallel faces, wherein the upper face is a flux entry face, and the lower face is a flux exit face;

wherein the first outside radial face of the first lower major radial permanent magnet is magnetically coupled to the first inside radial face of the first lower axial permanent magnet and the second outside radial face of the first lower major radial permanent magnet is magnetically coupled to the second inside radial face of the first lower axial permanent magnet;

wherein the first outside radial face of the second lower major radial permanent magnet is magnetically coupled to the first inside radial face of the second lower axial permanent magnet and the second outside radial face of the second lower major radial permanent magnet is magnetically coupled to the second inside radial face of the second lower axial permanent magnet;

a central axial permanent magnet formed as a solid having an upper face opposite a lower face;

the central axial permanent magnet having a magnetization vector wherein its upper face is a flux exit face and its lower face is a flux entry face;

wherein at least a portion of the upper face of the central axial permanent magnet is magnetically coupled to at least a portion of the lower face of the first upper major radial permanent magnet and at least a portion of the lower face of the second upper major radial permanent magnet;

wherein at least a portion of the lower face of the central axial permanent magnet is magnetically coupled to at least a portion of the upper face of the first lower major radial permanent magnet and at least a portion of the upper face of the second lower major radial permanent magnet;

whereby a first gap experiencing a high magnetic field is formed between at least a portion of the lower face of the first upper axial permanent magnet and at least a portion of the upper face of the first lower axial permanent magnet, and a second gap experiencing a high magnetic field is formed between at least a portion of the lower face of the second upper axial permanent magnet and at least a portion of the upper face of the second lower axial permanent magnet.

22. The permanent magnet assembly of claim 21, further comprising:

a first, a second, a third, and a fourth upper radial blocking permanent magnet, and a first, a second, a third, and a fourth lower radial blocking permanent magnet;

each radial blocking permanent magnet formed as a rectangular block having six or more essentially planar faces comprising an upper face substantially parallel to and opposite a lower face, a first lateral face substantially parallel to and opposite a second lateral face, and an inside radial face substantially parallel to and opposite an outside radial face, wherein its upper and lower faces, its first and second lateral faces, and its inside and outside radial faces are substantially orthogonal;

each upper radial blocking permanent magnet having a magnetization vector wherein its inside radial face is a flux exit face, its outside radial face is a flux entry face, its first and second lateral faces are flux parallel faces, and its upper and lower faces are flux parallel faces;

each lower radial blocking permanent magnet having a magnetization vector wherein its inside radial face is a flux entry face, its outside radial face is a flux exit face, its first and second lateral faces are flux parallel faces, and its upper and lower faces are flux parallel faces;

wherein the first outside radial face of the first upper axial permanent magnet is magnetically coupled to the inside radial face of the first upper radial blocking permanent magnet;

wherein the second outside radial face of the first upper axial permanent magnet is magnetically coupled to the inside radial face of the second upper radial blocking permanent magnet;

wherein the first outside radial face of the second upper axial permanent magnet is magnetically coupled to the inside radial face of the third upper radial blocking permanent magnet;

wherein the second outside radial face of the second upper axial permanent magnet is magnetically coupled to the inside radial face of the fourth upper radial blocking permanent magnet;

wherein the first outside radial face of the first lower axial permanent magnet is magnetically coupled to the inside radial face of the first lower radial blocking permanent magnet;

wherein the second outside radial face of the first lower axial permanent magnet is magnetically coupled to the inside radial face of the second lower radial blocking permanent magnet;

wherein the first outside radial face of the second lower axial permanent magnet is magnetically coupled to the inside radial face of the third lower radial blocking permanent magnet; and

wherein the second outside radial face of the second lower axial permanent magnet is magnetically coupled to the inside radial face of the fourth lower radial blocking permanent magnet.

23. The permanent magnet assembly of claim 22, further comprising:

a first, a second, a third, and a fourth upper lateral blocking permanent magnet, and a first, a second, a third, and a fourth lower lateral blocking permanent magnet;

each lateral blocking permanent magnet formed as a rectangular block having six or more essentially planar faces comprising an upper face substantially parallel to and opposite a lower face, an inside lateral face substantially parallel to and opposite an outside lateral face, and an inside radial face substantially parallel to and opposite an outside radial face, wherein its upper and lower faces, its first and second lateral faces, and its inside and outside radial faces are substantially orthogonal;

each upper lateral blocking permanent magnet having a magnetization vector wherein its inside lateral face is a flux exit face, its outside lateral face is a flux entry face, its inside and outside radial faces are flux parallel faces, and its upper and lower faces are flux parallel faces;

each lower lateral blocking permanent magnet having a magnetization vector wherein its inside lateral face is a flux entry face, its outside lateral face is a flux exit face, its inside and outside radial faces are flux parallel faces, and its upper and lower faces are flux parallel faces;

wherein the first lateral face of the first upper axial permanent magnet is magnetically coupled to the inside lateral face of the first upper lateral blocking permanent magnet;

wherein the second lateral face of the first upper axial permanent magnet is magnetically coupled to the inside lateral face of the second upper lateral blocking permanent magnet;

wherein the first lateral face of the second upper axial permanent magnet is magnetically coupled to the inside lateral face of the third upper lateral blocking permanent magnet;

wherein the second lateral face of the second upper axial permanent magnet is magnetically coupled to the inside lateral face of the fourth upper lateral blocking permanent magnet;

wherein the first lateral face of the first lower axial permanent magnet is magnetically coupled to the inside lateral face of the first lower lateral blocking permanent magnet;

wherein the second lateral face of the first lower axial permanent magnet is magnetically coupled to the inside lateral face of the second lower lateral blocking permanent magnet;

wherein the first lateral face of the second lower axial permanent magnet is magnetically coupled to the inside lateral face of the third lower lateral blocking permanent magnet; and

wherein the second lateral face of the second lower axial permanent magnet is magnetically coupled to the inside lateral face of the fourth lower lateral blocking permanent magnet.

24. The permanent magnet assembly of claim 23, further comprising:

a first, a second, a third, and a fourth upper minor radial permanent magnet, and a first, a second, a third, and a fourth lower minor radial permanent magnet;

each minor radial permanent magnet formed as a rectangular block having six or more essentially planar faces comprising an upper face substantially parallel to and opposite a lower face, a first lateral face substantially parallel to and opposite a second lateral face, and an inside radial face substantially parallel to and opposite an outside radial face, wherein its upper and lower faces, its first and second lateral faces, and its inside and outside radial faces are substantially orthogonal;

each upper minor radial permanent magnet having a magnetization vector wherein its inside radial face is a flux entry face, its outside radial face is a flux exit face, its first and second lateral faces are flux parallel faces, and its upper and lower faces are flux parallel faces;

each lower minor radial permanent magnet having a magnetization vector wherein its inside radial face is a flux exit face, its outside radial face is a flux entry face, its first and second lateral faces are flux parallel faces, and its upper and lower faces are flux parallel faces;

wherein the first outside radial face of the first upper major radial permanent magnet is magnetically coupled to the inside radial face of the first upper minor radial permanent magnet and the outside radial face of the first upper minor radial permanent magnet is magnetically coupled to the first inside radial face of the first upper axial permanent magnet;

wherein the second outside radial face of the first upper major radial permanent magnet is magnetically coupled to the inside radial face of the second upper minor radial permanent magnet and the outside radial face of the second upper minor radial permanent magnet is magnetically coupled to the second inside radial face of the first upper axial permanent magnet;

wherein the first outside radial face of the second upper major radial permanent magnet is magnetically coupled to the inside radial face of the third upper minor radial permanent magnet and the outside radial face of the third upper minor radial permanent magnet is magnetically coupled to the first inside radial face of the second upper axial permanent magnet;

wherein the second outside radial face of the second upper major radial permanent magnet is magnetically coupled to the inside radial face of the fourth upper minor radial permanent magnet and the outside radial face of the fourth upper minor radial permanent magnet is magnetically coupled to the second inside radial face of the second upper axial permanent magnet;

wherein the first outside radial face of the first lower major radial permanent magnet is magnetically coupled to the inside radial face of the first lower minor radial permanent magnet and the outside radial face of the first lower minor radial permanent magnet is magnetically coupled to the first inside radial face of the first lower axial permanent magnet;

wherein the second outside radial face of the first lower major radial permanent magnet is magnetically coupled to the inside radial face of the second lower minor radial permanent magnet and the outside radial face of the second lower minor radial permanent magnet is magnetically coupled to the second inside radial face of the first lower axial permanent magnet;

wherein the first outside radial face of the second lower major radial permanent magnet is magnetically coupled to the inside radial face of the third lower minor radial permanent magnet and the outside radial face of the third lower minor radial permanent magnet is magnetically coupled to the first inside radial face of the second lower axial permanent magnet; and

wherein the second outside radial face of the second lower major radial permanent magnet is magnetically coupled to the inside radial face of the fourth lower minor radial permanent magnet and the outside radial face of the fourth lower minor radial permanent magnet is magnetically coupled to the second inside radial face of the second lower axial permanent magnet;

whereby the first upper major radial permanent magnet is indirectly magnetically coupled to the first upper axial permanent magnet, the second upper major radial permanent magnet is indirectly magnetically coupled to the second upper axial permanent magnet, the first lower major radial permanent magnet is indirectly magnetically coupled to the first lower axial permanent magnet, and the second lower major radial permanent magnet is indirectly magnetically coupled to the second lower axial permanent magnet.

25. The permanent magnet assembly of claim 21, further comprising:

a first, a second, a third, and a fourth upper lateral blocking permanent magnet, and a first, a second, a third, and a fourth lower lateral blocking permanent magnet;

each lateral blocking permanent magnet formed as a rectangular block having six or more essentially planar faces comprising an upper face substantially parallel to and opposite a lower face, an inside lateral face substantially parallel to and opposite an outside lateral face, and an inside radial face substantially parallel to and opposite an outside radial face, wherein its upper and lower faces, its first and second lateral faces, and its inside and outside radial faces are substantially orthogonal;

each upper lateral blocking permanent magnet having a magnetization vector wherein its inside lateral face is a flux exit face, its outside lateral face is a flux entry face, its inside and outside radial faces are flux parallel faces, and its upper and lower faces are flux parallel faces;

each lower lateral blocking permanent magnet having a magnetization vector wherein its inside lateral face is a flux entry face, its outside lateral face is a flux exit face, its inside and outside radial faces are flux parallel faces, and its upper and lower faces are flux parallel faces;

wherein the first lateral face of the first upper axial permanent magnet is magnetically coupled to the inside lateral face of the first upper lateral blocking permanent magnet;

wherein the second lateral face of the first upper axial permanent magnet is magnetically coupled to the inside lateral face of the second upper lateral blocking permanent magnet;

wherein the first lateral face of the second upper axial permanent magnet is magnetically coupled to the inside lateral face of the third upper lateral blocking permanent magnet;

wherein the second lateral face of the second upper axial permanent magnet is magnetically coupled to the inside lateral face of the fourth upper lateral blocking permanent magnet;

wherein the first lateral face of the first lower axial permanent magnet is magnetically coupled to the inside lateral face of the first lower lateral blocking permanent magnet;

wherein the second lateral face of the first lower axial permanent magnet is magnetically coupled to the inside lateral face of the second lower lateral blocking permanent magnet;

wherein the first lateral face of the second lower axial permanent magnet is magnetically coupled to the inside lateral face of the third lower lateral blocking permanent magnet; and

wherein the second lateral face of the second lower axial permanent magnet is magnetically coupled to the inside lateral face of the fourth lower lateral blocking permanent magnet.