Magnetic centering bearing with high-amplitude tilt control

• US 6,384,500 B1
• Filed: 06/23/2000
• Issued: 05/07/2002
• Est. Priority Date: 08/09/1999
• Status: Expired due to Fees

• Current Assignee: Alcatel SA (Nokia Corporation)
• Original Assignee: Alcatel SA (Nokia Corporation)
• Inventors: Chassoulier, Damien, Delamare, Jérôme, Yonnet, Jean-Paul, Chillet, Christian
• Primary Examiner(s): NGUYEN, TRAN N
• Application Number:
  US09/599,855
• Time in Patent Office: 683 Days
• Field of Search: 310/90.5, 310/162-166, 310/254, 310/266, 310/261, 310/46, 310/152, 310/82, 295/96--98, 318/100, 318/135, 318/701, 417/422.12, 417/423.14
• US Class Current: 310/90.5
• CPC Class Codes: F16C 32/044 Active magnetic bearings

Abstract

A magnetic bearing for centering and controlling tilting of a first body relative to a second body includes centering members adapted to center the first body magnetically relative to the second body at least in the direction transverse to the reference axis, two permanently magnetized rings carried by a first ferromagnetic armature fastened to the first body, an annular plurality of (at least three) tilt windings fastened to the second body and each including two groups of circumferential strands respectively adapted to face each of the permanently magnetized rings regardless of the orientation of the hollow outer part, and an excitation circuit adapted to apply excitation currents to the tilt windings adapted to generate tilting forces in the air-gaps.

Claims

1. A magnetic bearing for centering and controlling tilting of a first body, the first body being mobile in tilting within a range of angular movement from minus 5°

or lower to plus 5°

degrees or greater about a center of tilting, relative to a second body having a reference axis passing through the center of tilting, the bearing including centering members that center the first body magnetically relative to the second body at least in a direction transverse to the reference axis, the bearing further comprising;

two permanently magnetized rings carried by a first ferromagnetic armature fastened to the first body extending around the reference axis, where each of the two permanently magnetized rings has a magnetization direction that passes at all points at least approximately through the reference axis, wherein each of the permanently magnetized rings is parallel to the other and offset in a direction parallel to the reference axis and on respective opposite sides of the center of tilting and has free edges substantially forming portions of a common sphere centered on the center of tilting;

a plurality of annular tilt windings fastened to the second body and each including two groups of circumferential strands that respectively face the permanently magnetized rings regardless of the orientation of the hollow outer part relative to the center of tilting within the range of movement in tilting, wherein the annular windings are carried by a second ferromagnetic armature defining in conjunction with the magnetized rings air-gaps whose thickness remains constant throughout the range of angular movement in tilting; and

an excitation circuit that applies excitation currents to the tilt windings to generate tilt forces in the air-gaps.

2. A bearing according to claim 1, wherein the excitation circuit also applies to the tilt windings excitation currents to generate in the air-gaps centering forces in the direction parallel to the reference axis.

3. A bearing according to claim 1, wherein the rings have magnetization directions that at all points pass at least approximately through the center of tilting.

4. A bearing according to claim 1, wherein the two rings have a same diameter and are symmetrical to each other about the center of tilting, and wherein the tilt windings are symmetrical to each other about the transverse plane.

5. A bearing according to claim 1, wherein the two rings have a spacing in a plane containing the reference axis corresponding to an angular offset of at least 10°

relative to the center of tilting.

6. A bearing according to claim 1, wherein the circumferential strands of each group of each tilt winding are disposed adjacently on a spherical surface of the second armature centered on the center of tilting.

7. A bearing according to claim 1, wherein the rings have an angular amplitude in a plane passing through the reference axis greater than that of each group of circumferential strands of each tilt winding.

8. A bearing according to claim 1, wherein the rings have an angular amplitude in a plane passing through the reference axis less than that of each group of circumferential strands of each tilt winding.

9. A bearing according to claim 1, wherein the second armature is radially inside the first armature.

10. A bearing according to claim 1, wherein the plurality of tilt windings includes four windings disposed in two pairs of areas that are diametrically opposite relative to the reference axis and offset by 90°

.

11. A bearing according to claim 1, wherein the centering members include two parallel pluralities of annular centering windings fastened to the second ferromagnetic armature, each annular centering winding surrounds a respective portion of the second ferromagnetic armature, the respective portions of the second ferromagnetic armature are divided into two parallel pluralities of ferromagnetic portions respectively that face each of the permanently magnetized rings regardless of the orientation of the hollow outer part relative to the center of tilting within the range of angular movement in tilting, and wherein the excitation circuit applies excitation currents to the centering windings to generate forces for centering the first body in a radial direction.

12. A bearing according to claim 11, wherein the circumferential strands of the tilt windings extend along the respective portion of the second ferromagnetic armature around which the centering windings are wound.

13. A bearing according to claim 11, wherein the pluralities of centering windings and the plurality of tilt windings each include the same number of windings.

14. A bearing according to claim 11, wherein the tilt windings and the centering windings have substantially a same angular amplitude about the reference axis and substantially face each other in an axial direction.

15. A bearing according to claim 11, wherein each plurality of centering windings includes four windings divided into two pairs of areas, that are diametrically opposite relative to the reference axis and offset by 90°

.

16. A bearing according to claim 1, wherein the centering members include:

a hollow outer part made at least in part from a ferromagnetic material and fastened to the first body, wherein the hollow outer part has an inside surface whose shape is a portion of a sphere whose center is substantially coincident with the center of tilting, and wherein the hollow outer part extends around the reference axis on respective opposite sides of a transverse plane that is perpendicular to the reference axis and passes through the center of tilting; and

an inner part fastened to the second body, the inner part including a plurality of ferromagnetic areas that are offset angularly about the reference axis, each of the plurality of ferromagnetic areas defines in conjunction with the inside surface of the hollow outer part two centering air-gaps provided with a specific winding that generate magnetic flux lines closing across the centering two air-gaps, wherein the specific windings form part of a set of windings connected to the excitation circuit that generates magnetic fluxes in the centering air-gaps to center the hollow outer part relative to the inner part at least in the direction transverse to the reference axis.

17. A bearing according to claim 16, wherein the inner part includes two separate members that are disposed on respective opposite sides of the transverse plane and wherein each separate member includes a plurality of ferromagnetic areas offset angularly about the reference axis, each separate member including a group of windings that includes at least the specific windings of the ferromagnetic areas, and wherein the two separate members are separated in the direction parallel to the reference axis by a space having a reluctance that prevents flux lines generated by the group of windings of one of the separate members from crossing the space, and wherein the windings of each group are connected to the excitation circuit.

18. A bearing according to claim 17, wherein said space is occupied by a permanent magnet that is permanently magnetized in the direction parallel to the reference axis.

19. The bearing claimed in claim 17, wherein said space is a free space forming a fixed air-gap.

20. The bearing claimed in claim 17, wherein the ferromagnetic areas of each member are part of a common ferromagnetic part.

21. A bearing according to claim 17, wherein the ferromagnetic areas of the two members are symmetrical about the transverse plane.

22. A bearing according to claim 17, wherein each ferromagnetic area of each member includes first and second projections that are directed towards the inside surface of the hollow outer part to form the respective air-gaps of that area, and wherein the first projection has said respective specific winding wound around it.

23. A bearing according to claim 22, wherein the second projections in the ferromagnetic areas of one member form part of a common annular projection centered on the reference axis.

24. A bearing according to claim 22, wherein the group of windings of each member further includes an additional winding wound around that member between the first and second projections of the ferromagnetic areas of that member, and wherein the additional winding is connected to the excitation circuit, and wherein the excitation circuit applies excitation currents selectively to the additional windings of the members to generate magnetic fields in the air-gaps to apply to the hollow outer part centering forces in the direction parallel to the reference axis.

25. A bearing according to claim 17, wherein the excitation circuit is applies excitation currents selectively to the specific windings of the ferromagnetic areas of the members so as to generate magnetic fields in the air-gaps to apply to the hollow outer part forces in the direction parallel to the reference axis.

26. A bearing according to claim 17, wherein the specific windings of the ferromagnetic areas are adjacent.

27. A bearing according to claim 16, wherein the plurality of ferromagnetic areas includes four ferromagnetic areas divided into two pairs of areas that are diametrically opposed relative to the reference axis and offset by 90°

.

28. A bearing according to claim 16, wherein the centering members are radially inside the permanently magnetized rings and the annular plurality of tilt windings.

29. The bearing according to claim 1, wherein the plurality of annular tilt windings fastened to the second body are at least three in number.

30. The bearing according to claim 11, wherein the two parallel annular plurality of centering windings are at least three in number.

31. The bearing according to claim 16, wherein the plurality of ferromagnetic areas are at least three in number.

32. The bearing according to claim 17, wherein the plurality of ferromagnetic areas offset angularly about the reference axis are at least three in number.