Bidirectional hydrodynamic thrust bearing

Abstract

A thrust bearing assembly including a flexible thrust washer sandwiched between first and second races. The thrust washer includes notches between adjacent support regions. When a thrust load is applied to the bearing assembly, the thrust washer elastically flexes at the notched or unsupported regions and creates undulations in the washer's dynamic surface to create an initial hydrodynamic fluid wedge with respect to the corresponding dynamic surface of the second race. The gradually converging geometry created by these undulations promotes a strong hydrodynamic action that wedges a lubricant film of a predictable magnitude into the dynamic interface between the thrust washer and the second race in response to relative rotation. This lubricant film physically separates the dynamic surfaces of the thrust washer and second race from each other, thus minimizing asperity contact, and reducing friction, wear and bearing-generated heat, while permitting operation at higher load and speed combinations.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the preferred embodiment thereof which is illustrated in the appended drawings, which drawings are incorporated as a part hereof.

It is to be noted however, that the appended drawings illustrate only a typical embodiment of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

In the Drawings:

FIG. 1 is a plan view of a hydrodynamic thrust bearing assembly according to a preferred embodiment of the present invention;

FIG. 1A is a section view taken along lines 1A-1A of FIG. 1;

FIG. 1B is a fragmentary section view taken along lines 1B-1B of FIG. 1;

FIG. 1C is an enlarged fragmentary section view similar to FIG. 1B, and showing elastic deflection under thrust loading with the deflection exaggerated for purpose of illustration;

FIG. 2 is a cross-sectional elevation view of an alternate embodiment of the hydrodynamic thrust bearing assembly of the present invention;

FIG. 2A is a cross-sectional elevation view of the hydrodynamic thrust bearing assembly of FIG. 2 shown in conjunction with a shaft and housing;

FIGS. 3 and 4 are plan views of alternate embodiments of the hydrodynamic thrust bearing assembly of the present invention;

FIG. 5 is a perspective view of an alternate embodiment of the thrust washer according to the present invention;

FIG. 5A is an enlarged fragmentary cross-sectional view of the thrust washer of FIG. 5;

FIG. 6 is a cross-sectional elevation view of an alternate embodiment of the thrust washer according to the present invention;

FIG. 7 is a view similar to FIG. 1B of another embodiment of the thrust washer according to the present invention, the thrust washer having a weakening slot in the notch;

FIG. 8 is a view similar to FIG. 1B of another embodiment of the thrust washer according to the present invention;

FIG. 8A is an enlarged fragmentary section view similar to FIG. 8, and showing elastic deflection under thrust loading with the deflection exaggerated for purpose of illustration; and

FIGS. 9 and 10 are perspective views of alternate embodiments of the thrust washer according to the present invention.

Claims

1. A hydrodynamic bearing assembly for supporting and guiding a relatively rotatable member, the hydrodynamic bearing assembly comprising: a first race having a static race surface;a second race having a dynamic race surface; anda thrust washer positioned between said first race and said second race, said thrust washer having a dynamic washer surface facing said dynamic race surface and a plurality of notches defined by a plurality of pedestals, said plurality of pedestals facing said static race surface,wherein each of said plurality of notches defines a washer flexing region.

2. The hydrodynamic bearing assembly of claim 1, further comprising an anti-rotation projection preventing rotational slippage between said first race and said thrust washer.

3. The hydrodynamic bearing assembly of claim 2, wherein said anti-rotation projection projects from said first race and engages an anti-rotation recess in said thrust washer.

4. The hydrodynamic bearing assembly of claim 2, wherein said anti-rotation projection projects from said thrust washer and engages said first race.

5. The hydrodynamic bearing assembly of claim 1, wherein said thrust washer includes a lubricant passage.

6. The hydrodynamic bearing assembly of claim 5, wherein said lubricant passage is a recessed slot in said dynamic washer surface.

7. The hydrodynamic bearing assembly of claim 5, wherein said lubricant passage is a hole that passes through said thrust washer from said dynamic washer surface to one of said plurality of notches.

8. The hydrodynamic bearing assembly of claim 7, further comprising a weakening geometry located substantially midway between an adjacent pair of said plurality of pedestals.

9. The hydrodynamic bearing assembly of claim 1, further comprising a weakening geometry located substantially midway between an adjacent pair of said plurality of pedestals.

10. The hydrodynamic bearing assembly of claim 1, further comprising a lubricant lubricating a dynamic interface between said dynamic race surface and said dynamic washer surface during relative rotation therebetween.

11. The hydrodynamic bearing assembly of claim 10, wherein during relative rotation between said dynamic race surface and said dynamic washer surface, said dynamic interface is lubricated substantially the same during either clockwise or counter-clockwise relative rotation.

12. The hydrodynamic bearing assembly of claim 1, wherein each said notch of said plurality of notches is substantially bilaterally symmetrical.

13. The hydrodynamic bearing assembly of claim 1, wherein said second race includes a plurality of pressure communication holes.

14. The hydrodynamic bearing assembly of claim 13, wherein each of said plurality of pressure communication holes passes substantially axially through said second race.

15. The hydrodynamic bearing assembly of claim 1, wherein said second race includes a peripheral undercut defining a flexible ledge.

16. The hydrodynamic bearing assembly of claim 1, wherein: said second race has a second race outside diameter and a second race inside diameter; andsaid first race has a first race outside diameter and a first race inside diameter,wherein said second race outside diameter is larger than said first race outside diameter, and said second race inside diameter is larger than said first race inside diameter.

17. The hydrodynamic bearing assembly of claim 1, wherein: said second race has a second race outside diameter and a second race inside diameter; andsaid first race has a first race outside diameter and a first race inside diameter,wherein said second race outside diameter is smaller than said first race outside diameter, and said second race inside diameter is smaller than said first race inside diameter.

18. The hydrodynamic bearing assembly of claim 1, wherein said thrust washer includes at least one weakening geometry intermediate two of said plurality of pedestals.

19. The hydrodynamic bearing assembly of claim 1, wherein each of said plurality of pedestals includes an end surface and at least a portion of said end surfaces is roughened to increase friction between said plurality of pedestals and said static race surface.

20. The hydrodynamic bearing assembly of claim 1, wherein at least a portion of said static race surface is roughened to increase friction between said plurality of pedestals and said static race surface.

21. The hydrodynamic bearing assembly of claim 1, wherein said dynamic race surface of said second race is silver plated.

22. A load responsive, hydrodynamic bearing assembly for supporting and guiding a first member rotatable relative to a second member, the bearing assembly comprising: a first race having a static race surface;a ring shaped second race having a dynamic race surface; anda ring shaped, flexible thrust washer positioned between said first race and said second race, said flexible thrust washer having a plurality of notches defined by a plurality of pedestals, said plurality of pedestals facing said static race surface, said flexible thrust washer having a dynamic washer surface facing said dynamic race surface,wherein a plurality of flexing regions are defined by said plurality of notches.

23. The hydrodynamic bearing assembly of claim 22, wherein during rotation of the first member relative to the second member, said dynamic race surface rotates relative to said dynamic washer surface forming a dynamic interface therebetween.

24. The hydrodynamic bearing assembly of claim 23, wherein said flexible thrust washer is rotationally stationary relative to said first race.

25. The hydrodynamic bearing assembly of claim 23, wherein said plurality of notches are open-ended notches such that said static race surface is not in contact with said flexible thrust washer at said plurality of flexing regions.

26. The hydrodynamic bearing assembly of claim 25, further comprising a lubricant lubricating said dynamic interface between said dynamic race surface and said dynamic washer surface during relative rotation therebetween.

27. The hydrodynamic bearing assembly of claim 26, wherein said lubricant is a pressurized lubricant and a film of lubricant is swept into said dynamic interface during relative rotation between said dynamic race surface and said dynamic washer surface.

28. The hydrodynamic bearing assembly of claim 26, wherein said flexible thrust washer elastically deforms in use to provide a hydrodynamic fluid wedge at said dynamic interface between said dynamic washer surface and said dynamic race surface.

29. The hydrodynamic bearing assembly of claim 27, wherein said pressurized lubricant establishes separation between said dynamic race surface and said dynamic washer surface.

30. The hydrodynamic bearing assembly of claim 22, wherein said dynamic washer surface is substantially planar.

31. The hydrodynamic bearing assembly of claim 30, wherein said dynamic race surface is substantially planar.

32. The hydrodynamic bearing assembly of claim 30, wherein said flexible thrust washer includes a plurality of lubricant passages.

33. The hydrodynamic bearing assembly of claim 32, wherein said plurality of lubricant passages comprise a plurality of recessed slots in said dynamic washer surface.

34. The hydrodynamic bearing assembly of claim 32, wherein said plurality of lubricant passages comprise a plurality of holes that pass through said flexible thrust washer from said dynamic washer surface to one of said plurality of notches.

35. The hydrodynamic bearing assembly of claim 30, wherein said second race includes a plurality of pressure communication holes.

36. The hydrodynamic bearing assembly of claim 35, wherein each of said plurality of pressure communication holes passes substantially axially through said second race.

37. The hydrodynamic bearing assembly of claim 23, wherein said flexible thrust washer elastically deforms in use to provide a hydrodynamic fluid wedge at said dynamic interface between said dynamic washer surface and said dynamic race surface.

38. The hydrodynamic bearing assembly of claim 22, further comprising a lubricant lubricating a dynamic interface between said dynamic race surface and said dynamic washer surface during relative rotation therebetween.

39. The hydrodynamic bearing assembly of claim 38, wherein during relative rotation between said dynamic race surface and said dynamic washer surface, said dynamic interface is lubricated substantially the same during either clockwise or counter-clockwise relative rotation.

40. The hydrodynamic bearing assembly of claim 22, wherein each said notch of said plurality of notches is substantially bilaterally symmetrical.

41. A hydrodynamic bearing assembly comprising: a first race having a first race dynamic surface;a second race having a second race dynamic surface; anda thrust washer positioned between said first race and said second race, said thrust washer having a first dynamic washer surface facing said first race dynamic surface and a second dynamic washer surface facing said second race dynamic surface, said thrust washer having a plurality of notches extending generally radially through said thrust washer, said plurality of notches separated by a plurality of pedestals,wherein each of said plurality of notches defines first and second washer flexing regions.

42. The hydrodynamic bearing assembly of claim 41, wherein said plurality of notches is located midway between said first and second dynamic washer surfaces.

43. The hydrodynamic bearing assembly of claim 41, wherein said plurality of notches is located closer to one said dynamic washer surface than to the other said dynamic washer surface.

44. The hydrodynamic bearing assembly of claim 41, wherein each of said plurality of notches includes a weakening geometry extending generally radially through said thrust washer.

45. The hydrodynamic bearing assembly of claim 44, wherein said weakening geometry is located substantially midway between an adjacent pair of said plurality of pedestals.

46. The hydrodynamic bearing assembly of claim 41, wherein said thrust washer includes a peripheral undercut defining a flexible ledge.

47. The hydrodynamic bearing assembly of claim 41, wherein said thrust washer includes a lubricant passage.

48. The hydrodynamic bearing assembly of claim 47, wherein said lubricant passage is a recessed slot in at least one of said dynamic washer surfaces.

49. The hydrodynamic bearing assembly of claim 47, wherein said lubricant passage is a hole that passes through said thrust washer from one of said dynamic washer surfaces to one of said plurality of notches.

50. The hydrodynamic bearing assembly of claim 41, further comprising a lubricant lubricating a dynamic interface between said first race dynamic surface and said first dynamic washer surface during relative rotation therebetween.

51. The hydrodynamic bearing assembly of claim 50, wherein during relative rotation between said first race dynamic surface and said first dynamic washer surface, said dynamic interface is lubricated substantially the same during either clockwise or counter-clockwise relative rotation.

52. The hydrodynamic bearing assembly of claim 50, wherein said lubricant is a pressurized lubricant and a film of lubricant is swept into said dynamic interface during relative rotation between said first race dynamic surface and said first dynamic washer surface.

53. The hydrodynamic bearing assembly of claim 41, wherein said thrust washer elastically deforms in use to provide a hydrodynamic fluid wedge at a dynamic interface between said first dynamic washer surface and said first race dynamic surface.

54. The hydrodynamic bearing assembly of claim 41, wherein each said notch of said plurality of notches is substantially bilaterally symmetrical.