Magnetic coupling using halbach type magnet array

• US 6,841,910 B2
• Filed: 10/02/2002
• Issued: 01/11/2005
• Est. Priority Date: 10/02/2002
• Status: Expired due to Fees

• Current Assignee: Quadrant Technologies Limited (Vectura Group Ltd.)
• Original Assignee: Quadrant Technologies Limited (Vectura Group Ltd.)
• Inventors: Gery, Jean-Marc
• Primary Examiner(s): NGUYEN, TRAN N
• Application Number:
  US10/263,081
• Publication Number:
  US 20040066107A1
• Time in Patent Office: 832 Days
• Field of Search: 310/103, 310/105, 310/114, 310/115, 310/75.R, 310/75.D, 310/92, 310/156.43, 310/154.28
• US Class Current: 310/103
• CPC Class Codes: H02K 49/106 with a radial air gap

Abstract

A magnetic coupling having two opposed annular arrays of angularly spaced permanent magnets magnetized to create magnetic north poles and magnetic south poles alternately spaced about each array. The north-pole and south-pole magnets of each array are tapered in cross-section from their surfaces at the gap to an annular surface of the array spaced from the gap, and permanent magnet spacer magnets completely fill in the space between the north-pole and south-pole magnets from the annular surface of the array at the gap to the spaced annular surface with the spacer magnets being magnetized generally transversely to the direction of magnetization of the adjacent north-pole, south-pole magnets so that the magnetic field created by the permanent magnets extends across the gap and annularly through each array to cause one of the arrays to rotate in synchronism with the other array.

Claims

1. A magnetic coupling comprising

a first annular permanent magnet array comprised of a plurality of separately magnetized permanent magnet segments in magnetic flux transmitting contact with each other angularly positioned about the array,

a second annular permanent magnet array comprised of a plurality of separately magnetized permanent magnet segments in magnetic flux transmitting contact with each other angularly positioned about the array, said second array being closely spaced from and positioned relative to the first array so as to form a uniform annular gap therebetween,

said permanent magnet segments of each array including at least one south-pole segment magnetized in a direction extending transversely of said gap so as to create a magnetic south pole at a face of the south-pole segment at the gap and including at least one north-pole segment magnetized in a direction extending transversely of said gap so as to create a magnetic north pole at a face of the north-pole segment at the gap, said south-pole and north-pole segments being alternately positioned about each array in angularly spaced positions,

said permanent magnet segments of each array further including separately magnetized permanent magnet spacer segments magnetized so as to transmit magnetic flux between the angularly spaced south-pole and north-pole segments of each array, said spacer segments filling the annular space between said north-pole and south-pole segments in each of the arrays,

means for mounting for rotation one of said first and second arrays so that when said one of said arrays is rotated the other array is caused to rotate in synchronism therewith due to the magnetic flux coupling between each pair of generally opposed north-pole and south-pole segments across the gap,

and with each permanent magnet array having an inner annular surface at the gap and an outer annular surface spaced from the gap with the inner annular surface including the north-pole and south-pole faces, each north-pole and south-pole segment being tapered toward said outer annular surface of its array so as to have a relatively large surface area at the gap and a relatively small surface area at the outer annular surface of its array.

2. A magnetic coupling as set forth in claim 1 wherein said outer annular surface of each north-pole and south-pole segment is in the form of a knife-edge.

3. A magnetic coupling as set forth in claim 1 wherein said permanent magnet spacer segments of each array are uniform in shape with a single spacer segment being positioned between each adjacent pair of north-pole and south-pole segments, each of said spacer segments being magnetized in a direction transversely of the directions of magnification of the adjacent north-pole and south-pole segments.

4. A magnetic coupling as set forth in claim 1 wherein said permanent magnet spacer segments of at least one of said arrays are comprised of first spacer segments having an inner annular surface coextensive with the inner annular surface of the array between each adjacent pair of north-pole and south-pole segments and an outer annular surface shorter than the outer annular surface of the array between each adjacent pair of north-pole and south-pole segments and spaced from such north-pole and south-pole segments, said permanent magnet spacer segments of said one array being further comprised of second spacer segments filling the spaces between each first spacer segment and the adjacent north-pole and south-pole segments, and each of said first and second spacer segments being magnetized generally transversely of its radially extending direction in the array so as to provide a multi-angled path for the magnetic flux through the array between each adjacent pair of north-pole and south-pole segments.

5. A magnetic coupling as set forth in claim 1 wherein said first and second permanent magnet arrays are arranged in a concentric relationship about a common axis of rotation.

6. A magnetic coupling as set forth in claim 1 wherein said first and second permanent magnet arrays have a common axis of rotation and wherein said gap extends in an axial direction between a pair of opposed north-pole and south-pole segments across the gap, said axial direction being parallel to said axis of rotation.

7. For use in a magnetic coupling, an annular permanent magnet array of angularly spaced permanent magnet segments of different magnetic polarities for generating a magnetic field across a gap directly adjacent to the array, said array having an inner annular surface at the gap and an outer annular surface spaced therefrom, said array comprising

at least one south-pole permanent magnet segment magnetized in a direction generally along a line passing transversely through the gap and bisecting said segment so as to create a magnetic south pole at the inner annular surface of the array,

at least one north-pole permanent magnet segment angularly spaced from said south-pole segment and magnetized in a direction generally along a line passing transversely through the gap and bisecting said segment so as to create a magnetic north pole at the inner annular surface of the array,

each of said north-pole and south-pole segments being tapered toward and extending to said outer annular surface of the array so as to have a relatively large surface area at the inner annular surface and a relatively small surface area at the outer annular surface,

and a plurality of permanent magnet spacer segments with one or more of said permanent magnet spacer segments being positioned between each adjacent pair of north-pole and south-pole segments to completely fill the annular space between the inner and outer annular surfaces of the array, each of said spacer segments being magnetized in a direction transversely of a radial line of the annular array bisecting the segment in order to maximize the magnetic field strength within a given radial dimension and volume of the array.

8. For use in a magnetic coupling, an annular permanent magnet array as set forth in claim 7 wherein said outer annular surface area of each north-pole segment and each south-pole segment is in the form of a knife-edge.

9. For use in a magnetic coupling, an annular permanent magnet array as set forth in claim 7 wherein the array has an axis of rotation and wherein said inner and outer annular surfaces of the array are located in a concentric relationship with respect to said axis of rotation.

10. For use in a magnetic coupling, an annular permanent magnet array as set forth in claim 7 wherein the array has an axis of rotation and wherein the inner and outer surfaces of the array are spaced in a direction that is parallel to said axis of rotation.

11. A magnetic drive for transferring torque between physically separated rotatable members, said drive comprising

a first annular permanent magnet array comprised of a plurality of separately magnetized permanent magnet segments in magnetic flux transmitting contact with each other angularly positioned about the array,

a second annular permanent magnet array comprised of a plurality of separately magnetized permanent magnet segments in magnetic flux transmitting contact with each other angularly positioned about the array, said second array being closely spaced from and positioned relative to the first array so as to form a uniform annular gap therebetween,

said permanent magnet segments of each array including at least one south-pole segment magnetized in a direction extending transversely of said gap so as to create a magnetic south pole at a face of the south-pole segment at the gap and including at least one north-pole segment magnetized in a direction extending transversely of said gap so as to create a magnetic north pole at a face of the north-pole segment at the gap, said south-pole and north-pole segments being alternately positioned about each array in angularly spaced positions,

said permanent magnet segments of each array further including separately magnetized permanent magnet spacer segments magnetized so as to transmit magnetic flux between the angularly spaced south-pole and north-pole segments of each array, said spacer segments filling the annular space between said north-pole and south-pole segments in each of the arrays,

and means for driving one of said arrays so that the other array is caused to rotate in synchronism therewith due to the magnetic flux coupling each pair of generally opposed north-pole and south-pole segments across the gap,

each permanent magnet array having an inner annular surface at the gap and an outer annular surface spaced from the gap with the inner annular surface including the north-pole and south-pole faces, each north-pole and south-pole segment being tapered toward said outer annular surface of its array so as to have a relatively large surface area at the gap and a relatively small surface area at the outer annular surface of its array.

12. A magnetic drive as set forth in claim 11 wherein said permanent magnet spacer segments of each array are uniform in shape with a single spacer segment being positioned between each adjacent pair of north-pole and south-pole segments, each of said permanent magnet spacer segments being magnetized in a direction transversely of the directions of magnification of the adjacent north-pole and south-pole segments.

13. A magnetic drive as set forth in claim 11 wherein said permanent magnet spacer segments of at least one of said arrays are comprised of first spacer segments having an inner annular surface coextensive with the inner annular surface of the array between each adjacent pair of north-pole and south-pole segments and an outer annular surface shorter than the outer annular surface of the array between each adjacent pair of north-pole and south-pole segments and spaced from such north-pole and south-pole segments, said permanent magnet spacer segments of said one array being further comprised of second spacer segments filling the spaces between each first spacer segment and the adjacent north-pole and south-pole segments, and each of said first and second spacer segments being magnetized generally transversely of its radially extending direction in the array so as to provide a multi-angled path for the magnetic flux through the array between each adjacent pair of north-pole and south-pole segments.

14. A magnetic drive as set forth in claim 11 wherein said first and second permanent magnet arrays are arranged in a concentric relationship about a common axis of rotation.