Bearing support damping

• US 9,714,584 B2
• Filed: 06/18/2015
• Issued: 07/25/2017
• Est. Priority Date: 06/18/2015
• Status: Active Grant

• Current Assignee: Rtx Corporation
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Morris, Robert J.
• Primary Examiner(s): Johnson, Phillip A
• Application Number:
  US14/742,766
• Publication Number:
  US 20160369652A1
• Time in Patent Office: 768 Days
• CPC Class Codes: F01D 25/164 Flexible supports; Vibration damping means associated with the bearing
• CPC Class Codes: F01D 25/18 Lubricating arrangements of machines or engines in general F01M
• CPC Class Codes: F02C 7/06 Arrangements of bearings bearings F16C; Lubricating of turbo machines F01D25/18; of machines or engines in general F01M
• CPC Class Codes: F05D 2220/32 in gas turbines
• CPC Class Codes: F05D 2240/50 Bearings
• CPC Class Codes: F16C 19/163 with angular contact
• CPC Class Codes: F16C 19/527 related to vibration and noise
• CPC Class Codes: F16C 2360/23 Gas turbine engines in general F02C
• CPC Class Codes: F16C 27/045 with a fluid film, e.g. squeeze film damping
• CPC Class Codes: F16C 27/066 Ball or roller bearings
• CPC Class Codes: F16C 35/077 between housing and outer race ring
• CPC Class Codes: F16F 15/02 Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems F16F15/005 takes precedence ; layered products B32B; suppression of vibration in ships B63; relieving load on bearings, using magnetic means F16C39/06
• CPC Class Codes: F16F 9/30 with solid or semi-solid material, e.g. pasty masses, as damping medium in devices where rotary elements are damped by viscous shear effect only, any throttling effect being immaterial F16F9/12; where members moving with a rotating system are being damped F16F15/16

Abstract

A damping treatment is applied to the ligaments of a squirrel cage type bearing support. The damping treatment reduces the vibrations transmitted to the engine casing as the engine passes through various resonance frequencies of the various parts of the gas turbine engine. A squeeze-film damper damps engine vibrations, but the oil in the squeeze-film damper can act as a stiffener during certain operational ranges, which increases the transmission of vibrations to the engine structure. Applying a damping treatment to the ligaments of the squirrel cage provides effective vibration damping.

Claims

1. A bearing centering spring comprising:

a first end;

a second end;

a plurality of ligaments extending between and connecting the first end and the second end; and

a damping layer disposed on at least one of the plurality of ligaments, such that the damping layer extends along the at least one of the plurality of ligaments but does not span a gap disposed between adjacent ones of the plurality of ligaments.

2. The bearing centering spring of claim 1, wherein the damping layer comprises:

a constrained layer viscoelastic material.

3. The bearing centering spring of claim 1, wherein the damping layer comprises:

a plasma spray coating.

4. The bearing centering spring of claim 1, wherein the damping layer comprises:

a damping tape.

5. The bearing centering spring of claim 4, wherein the damping tape further comprises:

a viscoelastic polymer adhesive; and

a backing material attached to the viscoelastic polymer adhesive.

6. The bearing centering spring of claim 5, wherein the backing material comprises a metallic material.

7. A damping assembly comprising:

a bearing;

a squirrel cage disposed radially outward of and supporting the bearing, the squirrel cage comprising;

a first end;

a second end, the second end supporting the bearing;

a plurality of ligaments extending between and connecting the first end and the second end; and

a damping layer disposed on at least one of the plurality of ligaments, such that the damping layer extends along the at least one of the plurality of ligaments but does not span a gap disposed between adjacent ones of the plurality of ligaments; and

a housing disposed radially outward of the squirrel cage.

8. The damping assembly of claim 7, and further comprising:

a first piston ring disposed between the squirrel cage and the housing;

a second piston ring disposed between the squirrel cage and the housing;

an annulus defined by the squirrel cage, the housing, the first piston ring, and the second piston ring; and

an oil feed to the annulus.

9. The damping assembly of claim 8, and further comprising:

a valve attached to the oil feed.

10. The damping assembly of claim 9, wherein the valve remains in an open position during engine start up.

11. The damping assembly of claim 10, wherein the valve switches to a closed position after an engine speed exceeds an idle speed.

12. The damping assembly of claim 7, wherein the bearing comprises a thrust bearing.

13. The damping assembly of claim 7, wherein the damping layer comprises:

a constrained layer viscoelastic material.

14. The damping assembly of claim 7, wherein the damping layer comprises:

a plasma spray coating.

15. The damping assembly of claim 7, wherein the damping layer comprises:

a damping tape.

16. The damping assembly of claim 15, wherein the damping tape further comprises:

a viscoelastic polymer adhesive; and

a metallic backing.

17. A method of damping vibration in a gas turbine engine comprising:

damping engine vibrations with a damping layer disposed on at least one ligament of a squirrel cage, the squirrel cage supporting a bearing outer race, wherein the damping layer is applied to the squirrel cage by masking at least one end of the squirrel cage and immersing the squirrel cage in a material having damping properties;

supplying oil to an annulus disposed between the squirrel cage and a housing;

damping engine vibrations with the oil; and

switching off an oil supply to the annulus when the engine speed is at least at idle speed of the engine, whereby the engine vibrations transmitted through the bearing outer race are damped exclusively by the squirrel cage.