Magnetically active foil bearing

• US 5,519,274 A
• Filed: 09/07/1994
• Issued: 05/21/1996
• Est. Priority Date: 09/07/1994
• Status: Expired due to Fees

• Current Assignee: Rotodynamics-Seal Research, Inc.
• Original Assignee: Rotodynamics-Seal Research, Inc.
• Inventors: Scharrer, Joseph K.
• Primary Examiner(s): BUDD, MARK OSBORNE
• Application Number:
  US08/301,788
• Time in Patent Office: 622 Days
• Field of Search: 310/90.5, 384/103
• US Class Current: 310/90.5
• CPC Class Codes: F16C 17/024 with flexible leaves to create hydrodynamic wedge, e.g. radial foil bearings
• CPC Class Codes: F16C 32/0402 combined with other supporting means, e.g. hybrid bearings with both magnetic and fluid supporting means
• CPC Class Codes: F16C 32/044 Active magnetic bearings

Abstract

A foil bearing operable with a magnetic field providing for magnetic suspension of a shaft. In one embodiment, the bearing construction relies upon a plurality of magnetic field generating members arranged to provide a shaft forming space to envelopingly receive the shaft and effectively suspend same in a composite magnetic field. In one embodiment, each of the magnetic field generating member include coils which are energizable with an electric current. In another embodiment, the magnetic field generating members comprise permanent magnets which are used in combination to create the composite magnetic field. A foil is trained about each of the magnetic field generating elements and the foils on each of these elements effectively define the space or cavity which receives the shaft Thus, when the shaft is levitated in the space or cavity by the composite magnetic field, it can function as a rotor and can be caused to rotate through a force applied to the shaft or a housing which receives the shaft. If the magnetic fields should fail or weaken, the shaft is still supported by the foils in the same manner as with foil barings.

Claims

1. A foil bearing providing for magnetic suspension and foil suspension of a shaft, said foil bearing comprising:

a) housing means;

b) a plurality of circumferentially spaced apart foil support members retained on said housing means;

c) a foil located across at least part of each of said foil support members and having interiorly presented faces which are arranged to form a shaft receiving compartment; and

d) magnetic field generating means associated with each of said foil support members creating individual magnetic fields and where the magnetic fields created at the foil support members provide for magnetic suspension of the shaft, said shaft receiving compartment being arranged and shaped to form a bearing space so that the shaft is journaled by the plurality of foils and the magnetic field in the bearing space and where the foils and magnetic fields simultaneously cooperate with one another to maintain said shaft properly positioned in the bearing space.

2. The foil bearing of claim 1 further characterized in that the magnetic field generating means comprises a coil associated with certain of said foil support members to create individual electromagnetic fields and where the electromagnetic fields are combined to provide a composite electromagnetic field for suspension of the shaft.

3. The foil bearing of claim 1 further characterized in that said magnetic field generating means are permanent magnets associated with and forming part of said housing means.

4. The foil bearing of claim 1 further characterized in that said foil supports are arranged so as to provide a shaft receiving space and where the shaft is symmetrical about its central axis at any point along its axis.

5. The foil bearing of claim 1 further characterized in that said shaft is a rotor and the housing is a stator.

6. The foil bearing of claim 1 further characterized in that the shaft is a stator and the housing means is a rotor.

14. The foil bearing of claim 1 further characterized in that each foil is formed of a magnetic material having magnetic permeability.

15. The foil bearing of claim 1 further characterized in that a separate magnetic field generating means is associated with each of said foil support member.

16. The foil bearing of claim 1 further characterized in that a separate magnetic field generating means forms part of each of said foil support members and that the magnetic fields generated by the magnetic field generating means provides a primary force for suspension of the shaft with the foils maintaining the shaft in a linear position in the bearing space in the event of a drift of the shaft.

17. The foil bearing of claim 1 further characterized in that a foil is extended around each of said soil support members and are continuous about each of said support members.

18. The foil bearing of claim 17 further characterized in that each of said foil support members have concave faces presented inwardly toward said shaft receiving space and the foils on each foil support member extends over the concave face of that foil support member.

19. The foil bearing of claim 1 further characterized in that a separate magnetic field generating means forms part of each of said foil support members and that the magnetic fields generated by the magnetic field generating means provides a primary force for suspension of the shaft with the foils maintaining the shaft in a linear position in the bearing space in the event of a drift of the shaft, the foil at each support member is extended around said foil support member and is continuous about each of said support members, and each of said foil support members have concave faces presented inwardly toward said shaft receiving space and the foils on each foil support member extends over the concave face of that foil support member.

7. A magnetically active foil bearing structure providing for magnetic suspension of a shaft, said foil bearing structure comprising:

a) a plurality of circumferentially arranged magnetic field generating support elements which individually generate magnetic fields and where the magnetic field associated with each of the support elements combine to form a composite magnetic field;

b) each of said magnetic field generating support elements having a concave surface with the concave surface facing inwardly to form somewhat of an arcuately shaped shaft receiving cavity and where the composite magnetic field generated is sufficient to support and journal a shaft;

c) a foil extending across said concave surface of each of said magnetic field generating support elements and also providing for a bearing surface facing inwardly into said shaft receiving cavity for also supporting said shaft; and

d) said magnetic field generating support elements also functioning as foil supports so that all of said foils in combination will journal and support said shaft in the event of a reduction or loss of said composite magnetic field such that the foils in Combination can function as a backup in the event Of such reduction or loss of magnetic field.

8. The magnetically active foil bearing structure of claim 7 further characterized in that means is provided for adjusting the tension of the foil on each magnetic field generating support element.

9. The magnetically active foil bearing structure of claim 8 further characterized in that the means for adjusting the tension comprises a rod insertable into a groove on the foil support and thereby forcing the foil into the groove.

10. The magnetically active foil bearing structure of claim 8 further characterized in that the means for adjusting the tension comprises a rotatable rod and the foil is trained about the rotatable rod.

11. The magnetically active foil bearing structure of claim 7 further characterized in that said bearing structure comprises a housing for receiving each of the foil supports and said housing is formed of a plurality of magnetically coupled laminated members.

12. The magnetically active foil bearing structure of claim 7 further characterized in that each of said magnetic field operating support elements are arcuately shaped.

13. The magnetically active foil bearing structure of claim 12 further characterized in that a substructure is located in said cavity.

20. A magnetically active foil bearing structure providing for magnetic suspension of a shaft, said foil bearing structure comprising:

a) a plurality of circumferentially arranged magnetic foil support elements which individually generate magnetic fields and where the magnetic field associated with each of the foil support elements combine to form a composite magnetic field sufficient to support a shaft;

b) a foil extending across a concave surface of each of said foil support elements and also providing for a bearing surface for said shaft; and

c) tension adjusting means for adjustment of the tension of the foil on the foil support comprising a rod insertable into a groove on the foil support and thereby forcing the foil into the groove.

21. A magnetically active foil bearing structure providing for magnetic suspension of a shaft, said foil bearing structure comprising:

a) a plurality of circumferentially arranged magnetic foil support elements which individually generate magnetic fields and where the magnetic field associated with each of the foil support elements combine to form a composite magnetic field sufficient to support a shaft;

b) a foil extending across a concave surface of each of said foil support elements and also providing for a bearing surface for said shaft;

c) each of said foil support elements being arcuately shaped and having inwardly presented concave surfaces forming a cavity at each foil support; and

d) a substructure located in the cavity of each foil support element.

22. The magnetically active foil bearing of claim 21 further characterized in that means is provided for adjusting the tension of the foil on the foil support.

23. A combination foil bearing and magnetic bearing providing for magnetic suspension of a shaft and an auxiliary foil suspension of the shaft, said combination foil and magnetic bearing comprising:

a) housing means;

b) a plurality of circumferentially arranged apart foil support members retained on said housing means and form a shaft receiving compartment therebetween;

c) recessed areas on each of said foil support members facing inwardly and defining said shaft receiving compartment;

d) magnetic field generating means associated with each of said foil support members creating individual magnetic fields and where the magnetic fields created at the foil support members provide for magnetic suspension of the shaft, said shaft receiving compartment being arranged and shaped to form a bearing space so that the shaft is journaled by the magnetic fields;

e) a foil located across at least the recessed area of each of said foil support members and having interiorly presented faces which are arranged to face and also form the shaft receiving compartment; and

f) said foils being spaced apart from said shaft so that the shaft is journaled by the magnetic fields and where the shaft will be supported and journaled by the foils in the event of any failure of the magnetic fields, such that the foils and foil support members serve as a back-up to the magnetic suspension of the shaft.

24. The combination foil and magnetic bearing of claim 23 further characterized in that the magnetic field generating means comprises an electromagnetic coil associated with certain of said foil support members to create individual electromagnetic fields and where the electromagnetic fields are combined to provide a composite magnetic field for suspension of the shaft.

25. The foil bearing of claim 23 further characterized in that said magnetic field generating means are permanent magnets associated with and forming part of said housing means.