Electromagnetic thrust bearing using passive and active magnets, for coupling a rotatable member to a stationary member

• US 5,315,197 A
• Filed: 08/16/1993
• Issued: 05/24/1994
• Est. Priority Date: 04/30/1992
• Status: Expired due to Term

• Current Assignee: Turbocor Inc.
• Original Assignee: Avcon-Advanced Controls Technology, Inc.
• Inventors: McMullen, Patrick T., Meeks, Crawford R.
• Primary Examiner(s): Voeltz, Emanuel T.
• Assistant Examiner(s): To, E.
• Application Number:
  US08/106,927
• Time in Patent Office: 281 Days
• Field of Search: 310/90, 310/90.5, 310/68 B
• US Class Current: 310/90.5
• CPC Class Codes: F16C 32/0465 with permanent magnets provided in the magnetic circuit of the electromagnets
• CPC Class Codes: F16C 32/0476 with active support of one degree of freedom, e.g. axial magnetic bearings

Abstract

An electromagnetic thrust bearing couples a rotatable member relative to a stationary member utilizing a combination of controllable electromagnets and a radially polarized permanent magnet, each physically associated with the stationary member. In one embodiment the rotatable member comprises a shaft having a pair of axially spaced apart thrust discs fixed thereto. A pair of solenoids are disposed about the rotatable member between the spaced apart thrust discs in oppositely facing relating to axially-facing sides of the thrust discs. The solenoids are capable of generating a controllable electromagnetic field. An arcuate radially polarized permanent magnet is disposed between the solenoids to generate a constant flux high density magnetic field between a solenoid housing and the thrust discs. In a second embodiment, a pair of solenoids are disposed about the rotatable member in facing relating on opposite sides of a single thrust disc. A radially polarized permanent magnet is disposed between the solenoids radially outwardly from the thrust disc for generating a constant flux high density magnetic field between solenoid housings and the thrust disc. A sensor determines the axial positioning of the rotatable member relative to the stationary member and provides input for controlling the positioning of the thrust disc(s) by varying the magnetic flux generated by the solenoids.

Claims

1. An electromagnetic thrust bearing for coupling a rotatable member relative to a stationary member, the thrust bearing comprising:

thrust disc means fixed to and extending radially from the rotatable member;

an arcuate permanent magnet associated with the stationary member, for generating a constant flux high density magnetic field linking the thrust disc means to the stationary member; and

a pair of solenoids associated with the stationary member and disposed about the rotatable member in oppositely facing relation to axially-facing sides of the thrust disc means, for generating a controllable electromagnetic field linking the thrust disc means to the stationary member;

wherein the permanent magnet and the solenoids cooperatively axially position the rotatable member relative to the stationary member.

2. An electromagnetic thrust bearing as set forth in claim 1, wherein each solenoid includes a controllable electromagnetic coil situated within a ferromagnetic housing which circumscribes a portion of the rotatable member.

3. An electromagnetic thrust bearing as set forth in claim 1, wherein the solenoids are axially aligned with one another and cooperatively generate a controllable, axially polarized electromagnetic field to magnetically link the thrust disc means to the solenoids and provide a magnetic flux path for electromagnetically generated flux around the permanent magnet and the electromagnetic coils.

4. An electromagnetic thrust bearing as set forth in claim 1, wherein the permanent magnet is radially polarized.

5. An electromagnetic thrust bearing as set forth in claim 1, wherein the permanent magnet is disposed between the pair of solenoids.

6. An electromagnetic thrust bearing as set forth in claim 1, including sensor means for determining axial positioning of the rotatable member relative to the stationary member, and for controlling the positioning of the thrust disc means by varying the magnetic flux generated by the solenoids.

7. An electromagnetic thrust bearing as set forth in claim 1, wherein the thrust disc means includes a pair of axially spaced apart thrust discs, and wherein the pair of solenoids are disposed between the axially spaced apart thrust discs.

8. An electromagnetic thrust bearing as set forth in claim 7, wherein the permanent magnet is disposed between the pair of solenoids and is radially polarized.

9. An electromagnetic thrust bearing as set forth in claim 1, wherein the thrust disc means comprises a single thrust disc, and wherein the pair of solenoids are disposed about the rotatable member in facing relation on opposite axially-facing sides of the thrust disc.

10. An electromagnetic thrust bearing as set forth in claim 9, wherein the permanent magnet is disposed radially outwardly from the thrust disc.

11. An electromagnetic thrust bearing for axially flux coupling a rotatable member relative to a stationary member, the thrust bearing comprising:

thrust disc means fixed to and extending radially from the rotatable member, the thrust disc means having first and second opposite, axially facing, sides;

first means associated with the stationary member and adjacent to the first side of the thrust disc means, for generating an axially polarized, controllable electromagnetic field;

second means associated with the stationary member and adjacent to the second side of the thrust disc means, for generating an axially polarized, controllable electromagnetic field;

means associated with the stationary member and disposed between the first and second electromagnetic field generating means, for generating a constant flux, high density magnetic field; and

means for directing substantially all magnetic flux from the first and second electromagnetic field generating means and the constant flux magnetic field generating means, axially between the thrust disc means and the stationary member, to provide controlled magnetic flux coupling of the rotatable member to the stationary member.

12. An electromagnetic thrust bearing as set forth in claim 11, wherein the constant flux magnetic field generating means includes a radially polarized, arcuate permanent magnet.

13. An electromagnetic thrust bearing as set forth in claim 12, wherein the first and second means for generating an axially polarized, controllable electromagnetic field each include an electromagnetic coil circumferentially positioned about the rotatable member and axially spaced from the thrust disc means.

14. An electromagnetic thrust bearing as set forth in claim 13, wherein the electromagnetic coils are axially aligned with the permanent magnet.

15. An electromagnetic thrust bearing as set forth in claim 13, wherein the stationary member includes spaced apart, facing first and second coil housings which circumferentially surround a portion of the rotatable member and wherein the thrust disc means is situated between the facing coil housings.

16. An electromagnetic thrust bearing as set forth in claim 15, wherein the electromagnetic coils are axially aligned with one another and cooperatively generate a controllable, axially polarized electromagnetic field to magnetically link the thrust disc means to the facing coil housings, wherein a magnetic flux path is provided for electromagnetically generated flux around the permanent magnet and the electromagnetic coils.

17. An electromagnetic thrust bearing as set forth in claim 16, wherein the permanent magnet is disposed radially relative to the thrust disc means.

18. An electromagnetic thrust bearing as set forth in claim 14, wherein the thrust disc means comprises a pair of axially spaced apart thrust discs, and wherein the electromagnetic coils are disposed therebetween.

19. An electromagnetic thrust bearing as set forth in claim 11, including means for determining axial positioning of the rotatable member relative to the stationary member, and for controlling axial positioning of the thrust disc means by varying the magnetic flux generated by the first and second electromagnetic field generating means.

20. An electromagnetic thrust bearing for coupling a rotatable member relative to a stationary member, the thrust bearing comprising:

a pair of axially spaced apart thrust discs fixed to and extending radially from the rotatable member;

means associated with the stationary member, for generating a constant flux high density magnetic field linking the thrust discs to the stationary member; and

means associated with the stationary member and disposed between the axially spaced apart thrust discs, for generating a controllable electromagnetic field linking the thrust discs to the stationary member;

wherein the constant flux magnetic field generating means and the controllable electromagnetic field generating means cooperatively axially position the rotatable member relative to the stationary member.

21. An electromagnetic thrust bearing as set forth in claim 20, wherein the constant flux magnetic field generating means is linked magnetically to the thrust discs through two air gaps such that axially directed flux from the constant flux magnetic field generating means passes through the air gaps to create a high density magnetic field linking the rotatable member to the stationary member.

22. An electromagnetic thrust bearing as set forth in claim 20, wherein the electromagnetic field generating means includes a pair of solenoids disposed about the rotatable member between the thrust discs.

23. An electromagnetic thrust bearing as set forth in claim 20, wherein each solenoid includes a controllable electromagnetic coil situated within a ferromagnetic housing which circumscribes a portion of the rotatable member.

24. An electromagnetic thrust bearing as set forth in claim 23, wherein the solenoids are axially aligned with one another and cooperatively generate a controllable, axially polarized, electromagnetic field to magnetically link the thrust discs to the solenoids and provide a magnetic flux path for electromagnetically generated flux around the constant flux magnetic field generating means and the electromagnetic coils.

25. An electromagnetic thrust bearing as set forth in claim 21, wherein the constant flux magnetic field generating means includes an arcuately shaped permanent magnet disposed between the axially spaced apart thrust discs.

26. An electromagnetic thrust bearing as set forth in claim 25, wherein the permanent magnet is radially polarized.

27. An electromagnetic thrust bearing as set forth in claim 22, wherein the constant flux magnetic field generating means includes an arcuately shaped permanent magnet disposed between the axially spaced apart thrust discs, wherein the permanent magnet is further disposed between the pair of solenoids.

28. An electromagnetic thrust bearing as set forth in claim 20, including sensor means for determining axial positioning of the rotatable member relative to the stationary member, and for controlling positioning of the thrust discs by varying the magnetic flux generated by the controllable electromagnetic field generating means.