Bearing assembly and method

Abstract

A bearing assembly and method in which a bearing cage is disposed around a rotating member and a housing is disposed around the cage. A first portion of the radial outer surface of the cage extends in a slightly spaced relation to the corresponding portion of the inner surface of the housing, and a second portion of the radial outer surface of the cage projects from the first portion in a radial direction and engages the corresponding portion of the inner surface of the housing.

Description

BACKGROUND

[0002] This invention relates to a bearing assembly and method for a rotating member, and, more particularly, to a bearing assembly and method involving a bearing cage that extends between the rotating member and a bearing housing.

[0003] In many bearing designs of the above type, it is necessary to have a fairly precise engagement between the bearing cage and the bearing housing that will be sufficient through the range of manufacturing clearances of these components, yet will maintain a positive seal at the joint between the housing and cage. Also, it is important that the bearing geometry be controlled and that the clamping force not be high enough to cause bending or deformity.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] FIG. 1 is a cross-sectional view of the bearing assembly according to an embodiment of the present invention, shown in operative engagement with a rotor, which is shown in elevation.

[0005] FIG. 2 is an enlarged cross-sectional view of a portion of the bearing assembly of FIG. 1.

[0006] FIGS. 3 and 4 are views, similar to FIGS. 1 and 2, respectively, but depicting an alternate embodiment of the present invention.

[0007] FIGS. 5 and 6 are views, similar to FIGS. 1 and 2, respectively, but depicting another alternate embodiment of the present invention.

DETAILED DESCRIPTION

[0008] Referring to FIG. 1 of the drawings, the reference numeral 10 refers in general to the bearing assembly according to an embodiment of the invention which surrounds a rotor 12. It is understood that the rotor 12 is rotated about its axis and forms part of an assembly that includes a driving system for imparting torque to the rotor, in a conventional manner.

[0009] An annular bearing cage 16 extends around the rotor 12 and has an internal recess formed therein for receiving a series of tilt pads 18, one of which is shown, which form the bearing members. Since the tilt pads 18 are conventional, they will not be described in detail.

[0010] Two axially-extending grooves 16a and 16b are formed in the outer periphery of the cage 16 with each extending for approximately 180 degrees. The grooves 16a and 16b are spaced radially inwardly from the outer radial surface of the cage 16 a predetermined amount to form cantilevered portions 16c and 16d that extend radially outwardly from the respective grooves. The thickness of each cantilevered portion 16c and 16d is such that it functions as a mechanical spring. It is understood that the thickness of each portion 16c and 16d, and therefore the stiffness of the mechanical spring formed by each portion, can be adjusted relative to the bearing stiffness of the tilt pads 18.

[0011] A radially-extending passage 16e is formed through the center of the cage 16 for supplying lubricating oil to the tilt pad 18, in a manner to be explained.

[0012] An annular housing 20 surrounds the cage 16 and has an internal annular recess 20a which communicates with the passage 16e of the cage 16 and with a radially-extending through passage 20b. Oil can thus be introduced to the passage 20b and passes through the latter passage, the recess 20a and the passage 16e for supplying oil to the tilt pads 18.

[0013] A majority of the radial inner surface of the housing 20 is slightly spaced from the radial outer surface of the cage 16, including the cantilevered portions 16c and 16d, to form an annular clearance C which communicates with the recess 20a of the housing 20 and thus receives some of the above-mentioned oil.

[0014] As better shown in FIG. 2, the axial end portion of the radial outer surface of each cantilevered portions 16c and 16d is enlarged as shown by the reference numeral 16f in connection with the cage portion 16c. The enlarged portions, including the portion 16f, project radially outwardly from the plane of the latter portions. Although the enlarged portion 16f is shown slightly spaced from the corresponding inner surfaces of the housing 20 in FIG. 1 in the interest of clarity, the enlarged portions actually engage the latter surfaces in an interference fit to prevent the leakage of oil from the clearance C. Also, the axial lengths of the enlarged portions, including the portion 16f are designed to minimize contact stresses between the cage 16 and the housing 20.

[0015] The system 10 thus has the following advantages:

[0016] 1. A relatively low clamping force acts on the bearing housing 20 to eliminate the risk of deformation and leakage.

[0017] 2. No deformation of the inside of the cage 16 occurs where the tilt pads 18 contact the cage, allowing a much better control of the tilt pad bearing geometry.

[0018] 3. There is less sensitivity to temperature effects on the housing 20 resulting in minimum deleterious effects on the interference fit between the enlarged portions, including portion 16f, of the cantilevered portions 16c and 16d and the corresponding surfaces of the housing 20.

[0019] 4. The presence of the oil in the clearance C provides additional damping of the bearing assembly 10 in general, thus significantly increasing the damping provided to the rotor 12.

[0020] Referring to FIG. 3, the reference numeral 30 refers, in general, to the bearing assembly according to another embodiment of the invention. The bearing assembly 30 surrounds a rotor 32 which is rotated about its axis and forms part of an assembly that includes a driving system for imparting torque to the rotor, in a conventional manner.

[0021] An annular bearing cage 36 extends around the rotor 32 and has an internal recess formed therein for receiving a series of tilt pads 38, one of which is shown, which form the bearing members. Since the tilt pads 38 are conventional they will not be described in detail. A radially-extending passage 36a is formed through the center of the cage 36 for supplying lubricating oil to the tilt pad 38, in a manner to be explained.

[0022] An annular housing 40 surrounds the cage 36 and has an internal annular recess 40a which communicates with the passage 36a of the cage 36 and with a radially-extending through passage 40b. Oil can thus be introduced to the passage 40b and passes through the latter passage, the recess 40a and the passage 36a for supplying oil to the tilt pads 38.

[0023] Two axially-extending grooves 40c and 40d are formed in the outer periphery of the housing 40 and each extends for approximately 180 degrees. The grooves 40c and 40d are spaced radially outwardly from the inner radial surface of the housing 40 a predetermined amount to form cantilevered portions 40e and 40f that extend radially inwardly from the respective grooves. The thickness of each cantilevered portion 40e and 40f is such that it functions as a mechanical spring. It is understood that the thickness of each cantilevered portion 40e and 40f, and therefore the stiffness of the mechanical spring formed by each portion, can be adjusted relative to the bearing stiffness of the tilt pads 38.

[0024] A majority of the radial inner surface of the housing 40, including the cantilevered portions 40e and 40f, is radially spaced from the radial outer surface of the cage 36 to form an annular clearance C which communicates with the recess 40a of the housing 40 and thus receives some of the above-mentioned oil.

[0025] As better shown in FIG. 4, an axial end portion 36b of the radial outer surface of the cage 36 is enlarged so as to project radially outwardly from the plane of the latter portion. Although FIG. 3 depicts the end portion 36b slightly spaced from the corresponding inner surfaces of the housing 40 in the interest of clarity, it actually engages the latter surfaces in an interference fit to prevent the leakage of oil from the clearance C. Also, the axial length of the enlarged end portion 36b is designed to minimize contact stresses between the cage 36 and the housing 40.

[0026] Thus, the embodiment of FIGS. 3 and 4 enjoys all the advantages of the embodiment of FIGS. 1 and 2 set forth above.

[0027] A bearing assembly according to another embodiment of the invention is shown, in general by the reference numeral 50 in FIGS. 5 and 6. As shown in FIG. 5, the bearing assembly 50 surrounds a rotor 52 which is rotated about its axis and forms part of an assembly that includes a driving system for imparting torque to the rotor, in a conventional manner.

[0028] An annular bearing cage 56 extends around the rotor 52 and has an internal recess formed therein for receiving a series of tilt pads 58, one of which is shown, which form the bearing members. Since the tilt pads 58 are conventional, they will not be described in detail.

[0029] Two axially-extending grooves 56a and 56b are formed in the outer periphery of the cage 56 with each extending for approximately 180 degrees. The grooves 56a and 56b are spaced radially inwardly from the outer radial surface of the cage 56 a predetermined amount to form cantilevered portions 56c and 56d that extend radially outwardly from the respective grooves. The thickness of each cantilevered portion 56c and 56d is such that it functions as a mechanical spring. The thickness of each cage portion 56c and 56d, and therefore the stiffness of the mechanical spring formed by each portion, can be adjusted relative to the bearing stiffness of the tilt pads 58.

[0030] A radially-extending passage 56e is formed through the center of the cage 56 for supplying lubricating oil to the tilt pad 58, in a manner to be explained.

[0031] An annular housing 60 surrounds the cage 56 and has an internal annular recess 60a which communicates with the passage 56e of the cage 56 and with a radially-extending through passage 60b. Oil can thus be introduced to the passage 60b and passes through the latter passage, the recess 60a, and the passage 56e for supplying oil to the tilt pads 58.

[0032] A majority of the radial inner surface of the housing 60 is slightly spaced from the radial outer surface of the cage 56, including the cantilevered portions 56c and 56d, to form an annular clearance C which communicates with the recess 60a of the housing 60 and thus receives some of the above-mentioned oil.

[0033] As better shown in FIG. 6, the axial end portion of the radial outer surface of each cantilevered portions 56c and 56d is enlarged as shown by the reference numeral 56f in connection with the cage portion 56c. The enlarged portions, including the portion 56f, project radially outwardly from the plane of the latter portions and engages the corresponding inner surfaces of the housing 60 in an interference fit. Although the enlarged portions, including the portion 56f, are shown slightly spaced from the corresponding inner surfaces of the housing 60 in FIGS. 5 and 6 in the interest of clarity, they actually engage the latter surfaces in an interference fit to prevent the leakage of oil from the clearance C. Also, the axial lengths of the enlarged portions, including the portion 56f, are designed to minimize contact stresses between the cage 56 and the housing 60.

[0034] Two axially-extending grooves 60c and 60d are formed in the outer periphery of the housing 60 and each extends for approximately 180 degrees. The grooves 60c and 60d are spaced radially outwardly from the inner radial surface of the housing 60 a predetermined amount to form cantilevered portions 60e and 60f that extend radially inwardly from the respective grooves. The thickness of each cantilevered portion 60e and 60f is such that it functions as a mechanical spring. The thickness of each cantilevered portion 60e and 60f, and therefore the stiffness of the mechanical spring formed by each portion, can be adjusted relative to the bearing stiffness of the tilt pads 58.

[0035] Thus, the embodiment of FIGS. 5 and 6 enjoys all the advantages of the embodiment of FIGS. 1 and 2, and the embodiment of FIGS. 3 and 4.

[0036] It is understood that variations may be made in each of the above embodiments without departing from the scope of the invention. For example, the number of angularly-spaced grooves formed in the cage and the housing in each of the above embodiments can vary and, in fact, there can be only one groove that is continuous in an angular direction. Also, the radial and axial lengths of the cage portions, including the enlarged portions, can vary from those shown in the drawings. Also, the sealing between the housings and their respective cages can be done by other means than metal-to-metal contact as shown on the drawings. Further, the cages and/or the housings can be formed by two split arcuate sections that are attached at their respective ends, in a conventional manner.

[0037] Since other modifications, changes, and substitutions are intended in the foregoing disclosure, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.

Claims

1. A bearing assembly for a rotor, the assembly comprising a cage surrounding the rotor, and a housing surrounding the cage, a first portion of the radial outer surface of the cage extending in a slightly spaced relation to the corresponding portion of the inner surface of the housing, and a second portion of the radial outer surface of the cage projecting from the first portion in a radial direction and engaging the corresponding portion of the inner surface of the housing.

2. The assembly of claim 1 wherein the cage and the housing are annular.

3. The assembly of claim 1 wherein at least one axially-extending groove is formed in the cage to form a cantilevered portion extending between the groove and the corresponding outer radial surface of the cage.

4. The assembly of claim 3 wherein the cantilevered portion forms a mechanical spring.

5. The assembly of claim 1 wherein at least one axially-extending groove is formed in the housing to form a cantilevered portion extending between the groove and the corresponding inner radial surface of the housing.

6. The assembly of claim 5 wherein the cantilevered portion forms a mechanical spring.

7. The assembly of claim 1 wherein a clearance is formed between the first portion of the radial outer surface of the cage and the corresponding portion of the inner surface of the housing, and further comprising a passage formed in the housing for introducing oil to the clearance.

8. The assembly of claim 7 further comprising a recess formed in the cage and a passage extending through the cage and to the recess, the latter passage receiving the oil from the clearance and passing it to the recess, and further comprising tilt pads disposed in the recess.

9. The assembly of claim 7 wherein the second portion of the radial outer surface of the cage is disposed at the respective axial end portions of the cage to prevent the leakage of oil from the clearance.

10. The assembly of claim 1 wherein the second portion of the radial outer surface of the cage is disposed at the respective axial end portions of the cage.

11. A method of positioning a bearing cage and a bearing housing around a rotating member, the method comprising disposing the cage around the rotor, and disposing the housing around the cage, with a first portion of the radial outer surface of the cage extending in a slightly spaced relation to the corresponding portion of the inner surface of the housing, and with a second portion of the radial outer surface of the cage projecting from the first portion in a radial direction and engaging the corresponding portion of the inner surface of the housing.

12. The method of claim 11 wherein the cage and the housing are annular.

13. The method of claim 11 further comprising forming at least one axially-extending groove in the cage to form a cantilevered portion extending between the groove and the corresponding outer radial surface of the cage.

14. The method of claim 13 wherein the cantilevered portion forms a mechanical spring.

15. The method of claim 11 further comprising forming at least one axially-extending groove in the housing to form a cantilevered portion extending between the groove and the corresponding inner radial surface of the housing.

16. The method of claim 15 wherein the cantilevered portion forms a mechanical spring.

17. The method of claim 11 wherein a clearance is formed between the first portion of the radial outer surface of the cage and the corresponding portion of the inner surface of the housing, and further comprising a passage formed in the housing for introducing oil to the clearance.

18. The method of claim 17 further comprising forming a recess formed in the cage and forming a passage extending through the cage and to the recess, the latter passage receiving the oil from the clearance and passing it to the recess, and further comprising providing a tilt pad in the recess.

19. The method of claim 17 wherein the second portion of the radial outer surface of the cage is disposed at the respective axial end portions of the cage to prevent the leakage of oil from the clearance.

20. The method of claim 11 wherein the second portion of the radial outer surface of the cage is disposed at the respective axial end portions of the cage.

21. A bearing assembly for a rotor, the assembly comprising a cage surrounding the rotor, a housing surrounding the cage, and at least one axially-extending groove formed in the cage to form a cantilevered portion extending between the groove and a corresponding surface of the housing to form a mechanical spring.

22. The assembly of claim 21 wherein a portion of the radial outer surface of the cage extends in a slightly-spaced relation to a corresponding portion of the inner surface of the housing to form a clearance.

23. The assembly of claim 22 wherein a portion of the radial outer surface of the cage projects from the first-mentioned portion in a radial direction and engages a corresponding portion of the inner surface of the housing.

24. The assembly of claim 22 further comprising a passage formed in the housing for introducing oil to the clearance.

25. The assembly of claim 21 further comprising a tilt pad supported by the cage which engages the rotor and wherein the thickness of the cantilevered portions, and therefore the thickness of the mechanical springs, correspond to the bearing thickness of the tilt pads.

26. A bearing assembly for a rotor, the assembly comprising a cage surrounding the rotor, a housing surrounding the cage, and at least one axially-extending groove formed in the housing to form a cantilevered portion extending between the groove and the corresponding surface of the cage to form a mechanical spring.

27. The assembly of claim 25 wherein a portion of the radial outer surface of the cage extends in a slightly-spaced relation to a corresponding portion of the inner surface of the housing to form a clearance.

28. The assembly of claim 27 wherein a portion of the radial outer surface of the cage projects from the first-mentioned portion in a radial direction and engages the corresponding portion of the inner surface of the housing.

29. The assembly of claim 27 further comprising a passage formed in the housing for introducing oil to the clearance.

30. The assembly of claim 26 further comprising a tilt pad supported by the cage which engages the rotor, and wherein the thickness of the cantilevered portions, and therefore the thickness of the mechanical springs, correspond to the bearing thickness of the tilt pads.

31. A bearing assembly for a rotor, the assembly comprising a cage surrounding the rotor, and a housing surrounding the cage, at least one axially-extending groove formed in the cage to form a cantilevered portion extending between the groove and the corresponding surface of the housing to form a mechanical spring, and at least one axially-extending groove formed in the housing to form a cantilevered portion extending between the groove and the corresponding surface of the cage to form another mechanical spring.

32. The assembly of claim 31 wherein a portion of the radial outer surface of the cage extends in a slightly spaced relation to a corresponding portion of the inner surface of the housing to form a clearance.

33. The assembly of claim 32 wherein another portion of the radial outer surface of the cage projects from the first-mentioned portion in a radial direction and engages a corresponding surface of the housing.

34. The assembly of claim 32 further comprising a passage formed in the housing for introducing oil to the clearance.

35. The assembly of claim 31 wherein the cage and the housing are annular.

36. A method of manufacturing a bearing assembly comprising providing a rotor, surrounding the rotor with a cage, surrounding the cage with a housing, forming at least one axially-extending groove formed in the cage to form a cantilevered portion extending between the groove and the corresponding surface of the housing to form a mechanical spring, and forming at least one axially-extending groove formed in the housing to form a cantilevered portion extending between the groove and the corresponding surface of the cage to form another mechanical spring.

37. The method of claim 36 wherein a portion of the radial outer surface of the cage extends in a slightly spaced relation to a corresponding portion of the inner surface of the housing to form a clearance.

38. The method of claim 37 wherein another portion of the radial outer surface of the cage projects from the first-mentioned portion a radial direction and engages a corresponding surface of the housing.

39. The method of claim 37 further comprising introducing oil to the clearance.

40. The method of claim 36 further comprising providing a tilt pad in the cage which engages the rotor, and adjusting the thickness of the cantilevered portions, and therefore the thickness of the mechanical springs, relative to the bearing thickness of the tilt pads.