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Title:
TURBOCHARGER HAVING THRUST BEARING ASSEMBLY
Document Type and Number:
WIPO Patent Application WO/2019/075283
Kind Code:
A1
Abstract:
A thrust bearing assembly for a turbocharger includes a first thrust portion (50) disposed on a turbocharger shaft of the turbocharger, a second thrust portion ( 52) disposed on the turbocharger shaft and spaced axially from the first thrust portion, and a washer spacer (54) disposed on the turbocharger shaft axially between the first thrust portion and the second thrust portion. The thrust bearing assembly includes a thrust bearing (48) disposed axially between the first thrust portion and the second thrust portion and about the washer spacer. The thrust bearing including a first bearing surface to define a first gap with the first thrust portion, a second bearing surface that is opposed to the first bearing surface to define a second gap with the second thrust portion, and a seal extending toward the washer spacer to define a third gap with the washer spacer. The thrust bearing has a fluid passage extending to the washer spacer to provide fluid to the first gap and the second gap. The thrust bearing and the washer spacer cooperate to define a dynamic seal to reduce lubricant flow to the second bearing surface when thrust load is applied to the first bearing surface of the thrust bearing.

Inventors:
ASHTON, Zachary S. (31 Hickory Hills Dr, Arden, North Carolina, 28704, US)
LONGACRE, Christian C. (83 Mount Royal Dr, Arden, North Carolina, 28704, US)
BISCHOF, Kenneth Richard (61 Ashley Woods Dr, Arden, North Carolina, 28704, US)
MOSCETTI, Jason P. (106 Braemar Dr, Hendersonville, North Carolina, 28791, US)
Application Number:
US2018/055540
Publication Date:
April 18, 2019
Filing Date:
October 12, 2018
Export Citation:
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Assignee:
BORGWARNER INC. (Patent Department, 3850 Hamlin RoadAuburn Hills, Michigan, 48326, US)
International Classes:
F16C17/04; F01D11/02; F02C7/28; F04D29/10; F16C33/10; F16C33/74; F16J15/447
Foreign References:
EP2420651A22012-02-22
US20170067472A12017-03-09
Attorney, Agent or Firm:
LAPRAIRIE, David M. et al. (Howard & Howard, Attorneys PLLC450 West Fourth Stree, Royal Oak Michigan, 48067, US)
Download PDF:
Claims:
What is claimed is;

1. A thrust bearing assembly for a turbocharger comprising:

a first thrust portion disposed on a turbocharger shaft of the turbocharger;

a second thrust portion disposed on the turbocharger shaft and spaced axially from the first thrust portion;

a washer spacer disposed on the turbocharger shaft axially between the first thrust portion and the second thrust portion; and

a thrust bearing being disposed axially between the first thrust portion and the second thrust portion and about the washer spacer, the thrust bearing including a first bearing surface to define a first gap with the first thrust portion, a second bearing surface that is opposed to the first bearing surface to define a second gap with the second thrust portion, and a seal extending toward the washer spacer to define a third gap with the washer spacer, the thrust bearing having a fluid passage extending to the washer spacer to provide fluid to the first gap and the second gap, wherein the thrust bearing and the washer spacer cooperate to define a dynamic seal to reduce lubricant flow to the second bearing surface when thrust load is applied to the first bearing surface of the thrust bearing.

2. A thrust bearing assembly as set forth in claim 1 wherein the first thrust portion is either one of a first thrust washer and a flinger sleeve.

3. A thrust bearing assembly as set forth in claim 2 wherein the second thrust portion is a second thrust washer.

4. A thrust bearing assembly as set forth in claim 3 wherein the washer spacer is either one of a separate washer spacer and the washer spacer integrated into the flinger sleeve. 5. A thrust bearing assembly as set forth in claim 3 or claim 4 wherein each of the first thrust washer and the second thrust washer is mounted on the turbocharger shaft and includes a first face and a second face that is opposed to the first face.

6. A thrust bearing assembly as set forth in any one of claims 3-5 wherein the washer spacer has a first end that abuts the first face of the first thrust washer and a second end opposed to the first end, the second end abutting the first face of the second thrust washer.

7. A thrust bearing assembly as set forth in any one of claims 1-6 wherein the thrust bearing has a bottom surface at a radial depth less than a radial depth of the seal.

8. A thrust bearing assembly as set forth in any one of claims 1-6 wherein the thrust bearing has a chamfered surface on a bottom surface thereof on a load bearing side adjacent the second gap.

9. A thrust bearing assembly as set forth in claim 8 wherein the washer spacer has an outer surface that extends axially relative to a longitudinal axis of the turbocharger shaft.

10. A thrust bearing assembly as set forth in any one of claims 1-6 wherein the thrust bearing has a bottom surface that extends axially relative to a longitudinal axis of the turbocharger shaft.

11. A thrust bearing assembly as set forth in claim 10 wherein the washer spacer has an outer surface that extends axially at an angle relative to the longitudinal axis of the turbocharger shaft.

12. A thrust bearing assembly as set forth in any one of claims 1-6 wherein the thrust bearing has a chamfered surface on a bottom surface thereof on an unloaded bearing side adjacent the first gap.

13. A thrust bearing assembly as set forth in claim 12 wherein the washer spacer has an outer surface that extends axially relative to a longitudinal axis of the turbocharger shaft and includes a chamfered surface that is parallel to the chamfered surface of the thrust bearing.

14. A turbocharger comprising:

a turbine wheel to receive exhaust gas from an internal combustion engine;

a turbocharger shaft coupled to and rotatable by the turbine wheel, the turbocharger shaft extending along a longitudinal axis;

a compressor wheel coupled to and rotatable by the turbocharger shaft for compressing air to be delivered to the internal combustion engine;

a thrust bearing assembly on the turbocharger shaft to provide axial support for the turbocharger shaft; and

the thrust bearing assembly comprising a first thrust washer and a second thrust washer, each of the first thrust washer and the second thrust washer being mounted on the turbocharger shaft and including a first face, and a second face that is opposed to the first face, a washer spacer disposed on the turbocharger shaft axially between the first thrust washer and the second thrust washer, the washer spacer having a first end that abuts the first face of the first thrust washer and a second end opposed to the first end, the second end abutting the first face of the second thrust washer, and a thrust bearing being disposed axially between the first thrust washer and the second thrust washer and about the washer spacer, the thrust bearing including a first bearing surface to define a first gap with the first face of the first thrust washer, a second bearing surface that is opposed to the first bearing surface to define a second gap with the first face of the second thrust washer, and a seal extending toward the thrust bearing spacer to define a third gap with the washer spacer, the thrust bearing having a fluid passage extending to the washer spacer to provide fluid to the first gap and the second gap, wherein the thrust bearing and the washer spacer cooperate to define a dynamic seal to reduce lubricant flow to the second bearing surface when thrust load is applied to the first bearing surface of the thrust bearing.

15. A turbocharger as set forth in claim 14 wherein the thrust bearing has a bottom surface at a radial depth less than a radial depth of the seal.

16. A turbocharger as set forth in claim 14 or claim 15 wherein the thrust bearing has a chamfered surface on a bottom surface thereof on a load bearing side adjacent the second gap and the washer spacer has an outer surface that extends axially relative to a longitudinal axis of the turbocharger shaft.

17. A turbocharger as set forth in any one of claims 14-16 wherein the thrust bearing has a bottom surface that extends axially relative to a longitudinal axis of the turbocharger shaft and the washer spacer has an outer surface that extends axially at an angle relative to the longitudinal axis of the turbocharger shaft.

18. A turbocharger as set forth in any one of claims 14-17 wherein the thrust bearing has a chamfered surface on a bottom surface thereof on an unloaded bearing side adjacent the first gap and the washer spacer has an outer surface that extends axially relative to a longitudinal axis of the turbocharger shaft and includes a chamfered surface that is parallel to the chamfered surface of the thrust bearing.

19. A turbocharger comprising:

a turbine wheel to receive exhaust gas from an internal combustion engine;

a turbocharger shaft coupled to and rotatable by the turbine wheel, the turbocharger shaft extending along a longitudinal axis; a compressor wheel coupled to and rotatable by the turbocharger shaft for compressing air to be delivered to the internal combustion engine;

a thrust bearing assembly on the turbocharger shaft to provide axial support for the turbocharger shaft; and

the thrust bearing assembly comprising a flinger sleeve having a first thrust portion disposed on a turbocharger shaft of the turbocharger;

a second thrust portion disposed on the turbocharger shaft and spaced axially from the first thrust portion;

said flinger sleeve having a washer spacer disposed on the turbocharger shaft axially between the first thrust portion and the second thrust portion; and

a thrust bearing being disposed axially between the first thrust portion and the second thrust portion and about the washer spacer, the thrust bearing including a first bearing surface to define a first gap with the first thrust portion, a second bearing surface that is opposed to the first bearing surface to define a second gap with the second thrust portion, and a seal extending toward the washer spacer to define a third gap with the washer spacer, the thrust bearing having a fluid passage extending to the washer spacer to provide fluid to the first gap and the second gap, wherein the thrust bearing and the washer spacer cooperate to define a dynamic seal to reduce lubricant flow to the second bearing surface when thrust load is applied to the first bearing surface of the thrust bearing.

20. A turbocharger as set forth in claim 19 wherein the thrust bearing has a bottom surface at a radial depth less than a radial depth of the seal.

21. A turbocharger as set forth in claim 19 or claim 20 wherein the thrust bearing has a chamfered surface on a bottom surface thereof on a load bearing side adjacent the second gap and the washer spacer has an outer surface that extends axially relative to a longitudinal axis of the turbocharger shaft.

22. A turbocharger as set forth in any one of claims 19 to 21 wherein the thrust bearing has a bottom surface that extends axially relative to a longitudinal axis of the turbocharger shaft and the washer spacer has an outer surface that extends axially at an angle relative to the longitudinal axis of the turbocharger shaft.

23. A turbocharger as set forth in any one of claims 19 to 22 wherein the thrust bearing has a chamfered surface on a bottom surface thereof on an unloaded bearing side adjacent the first gap and the washer spacer has an outer surface that extends axially relative to a longitudinal axis of the turbocharger shaft and includes a chamfered surface that is parallel to the chamfered surface of the thrust bearing.

Description:
TURBOCHARGER HAVING THRUST BEARING ASSEMBLY

BACKGROUND OF INVENTION

1. Field of Invention

[0001] The present invention relates generally to turbochargers and, more specifically, to a turbocharger having a thrust bearing assembly with dynamic sealing.

2. Description of the Related Art

[0002] It is known to provide a turbocharger for an engine of a vehicle such as an automotive vehicle. An automotive turbocharger typically includes a compressor wheel and a turbine wheel on a common turbocharger shaft supported by bearings in a bearing housing. The turbine wheel of the turbocharger extracts energy from exhaust gas from the engine, and the extracted energy is transferred to the compressor wheel. The compressor wheel increases an intake air density into the engine, which in turn allows for a greater quantity of fuel to be burned for a given air-fuel ratio. As a result, the engine develops more power.

[0003] In typical turbocharger operation, the forces acting on the compressor wheel and turbine wheel in an axial direction are of differing magnitude and the axial force moves a rotor of the compressor wheel against one of the two sides of the thrust bearing. This action reduces the clearance and subsequent flow on the loaded side of the thrust bearing and increases the clearance and subsequent flow on the unloaded side. This directly opposes the goal of the thrust bearing to get fluid flow to the loaded side without wasting additional flow and efficiency to unloaded regions.

[0004] Therefore, it is desirable to provide a turbocharger with a new thrust bearing assembly to reduce oil flow rate and drag losses from the unloaded side. It is also desirable to provide a turbocharger with a thrust bearing assembly that increases fluid flow and load capacity to the loaded side. It is further desirable to provide a turbocharger with a thrust bearing assembly having dynamic sealing to aid in preventing compressor side oil leaks due to excessive thrust bearing fluid flow. Thus, there is a need in the art to provide a turbocharger with a thrust bearing assembly that meets at least one of these desires. SUMMARY OF THE INVENTION

[0005] The present invention provides a thrust bearing assembly for a turbocharger includes a first thrust portion disposed on a turbocharger shaft of the turbocharger, a second thrust portion disposed on the turbocharger shaft and spaced axially from the first thrust portion, and a washer spacer disposed on the turbocharger shaft axially between the first thrust portion and the second thrust portion. The thrust bearing assembly includes a thrust bearing disposed axially between the first thrust portion and the second thrust portion and about the washer spacer. The thrust bearing including a first bearing surface to define a first gap with the first thrust portion, a second bearing surface that is opposed to the first bearing surface to define a second gap with the second thrust portion, and a seal extending toward the washer spacer to define a third gap with the washer spacer. The thrust bearing has a fluid passage extending to the washer spacer to provide fluid to the first gap and the second gap. The thrust bearing and the washer spacer cooperate to define a dynamic seal to reduce lubricant flow to the second bearing surface when thrust load is applied to the first bearing surface of the thrust bearing.

[0006] One advantage of the present invention is that a new thrust bearing assembly is provided for a turbocharger having dynamic sealing. Another advantage of the present invention is that the thrust bearing assembly lowers mechanical losses via lower fluid flow rate. Yet another advantage of the present invention is that the thrust bearing assembly has a higher load capacity due to more fluid flow to the loaded surface. Still another advantage of the present invention is that the thrust bearing assembly reduces risk of compressor side fluid leak.

[0007] Other objects, features, and advantages of the present invention will be readily appreciated as the same becomes better understood after reading the subsequent description taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a sectional view of a turbocharger, according to one embodiment of the present invention.

[0009] Figure 2 is an enlarged view of a portion of the turbocharger of Figure 1. [0010] Figure 3 is an enlarged sectional view of one embodiment of a thrust bearing assembly, according to the present invention, shown in the portion of the turbocharger of Figure 2.

[0011] Figure 4 is a sectional view of another embodiment, according to the present invention, of the thrust bearing assembly of Figures 2 and 3.

[0012] Figure 5 is a sectional view of yet another embodiment, according to the present invention, of the thrust bearing assembly of Figures 2 and 3.

[0013] Figure 6 is a sectional view of still another embodiment, according to the present invention, of the thrust bearing assembly of Figures 2 and 3.

[0014] Figure 7 is a sectional view of a further embodiment, according to the present invention, of the thrust bearing assembly of Figures 2 and 3.

[0015] Figure 8 is a sectional view of a still further embodiment, according to the present invention, of the thrust bearing assembly of Figures 2 and 3 illustrating a first operational position of the thrust bearing assembly.

[0016] Figure 9 is a view similar to Figure 8 illustrating a second operational position of the thrust bearing assembly.

DETAILED DESCRIPTION OF THE INVENTION

[0017] Referring now to the figures, where like numerals are used to designate like structure unless otherwise indicated, a turbocharger 20, according to one embodiment of the present invention, is shown in Figure 1. As illustrated in Figure 1 , the turbocharger 20 includes a housing, generally indicated at 22, having a turbine housing 24, a shaft or bearing housing 26, and a compressor housing 28. The turbine housing 26 has a turbine exhaust gas inlet 30 to receive exhaust gas from an internal combustion engine (not shown) and a turbine exhaust gas outlet 32. The compressor housing 28 has a compressor ambient air inlet 34 to receive ambient airflow as indicated by the arrow and a compressor air discharge outlet (not shown) to deliver compressed air to the internal combustion engine. The turbocharger 20 also includes a rotatable turbine wheel, generally indicated at 36, disposed in the turbine housing 24 and a rotatable compressor wheel, generally indicated at 38, disposed in the compressor housing 28. The turbocharger 20 further includes a rotatable turbocharger shaft 40 coupled to the turbine wheel 36 and the compressor wheel 38 and rotationally supported by bearings in the bearing housing 26.

[0018] Referring to Figures 1 and 2, the turbocharger shaft 40 extends along a longitudinal axis A. The turbine wheel 36 is solidly affixed to one end of the turbocharger shaft 40, becoming a shaft and wheel assembly, and the compressor wheel 38 is coupled to the other end of the turbocharger shaft 40 by a suitable mechanism such as threads or a nut. In the embodiment illustrated, the turbocharger 20 includes a bearing housing cover 41 and a thrust bearing assembly, generally indicated at 42, disposed in the bearing housing 26 and surrounding the turbocharger shaft 40 at an axial location between the compressor wheel 38 and a compressor-side journal bearing 43. The thrust bearing assembly 42 provides axial support for the turbocharger shaft 40. It should be appreciated that an example of a turbocharger having a thrust bearing assembly is disclosed in U.S. Patent Application Publication No. 2017/0067472 to Day et al, the entire disclosure of which is hereby expressly incorporated by reference.

[0019] Referring to Figures 2 and 3, in one embodiment of the turbocharger 20, the thrust bearing assembly 42 includes a flinger sleeve 44, a thrust washer sub-assembly, generally indicated at 46, and a thrust bearing 48. The bearing housing cover 41 can be securely sealed to the bearing housing 26, and cooperates with the flinger sleeve 44 to seal fluid such as oil from the compressor wheel 38 and to keep compressed air from leaking into the bearing housing 26. The flinger sleeve 44 is surrounded by the bearing housing cover 41 and provides a predetermined axial spacing between the compressor wheel 38 and the thrust washer subassembly 46. The flinger sleeve 44 is a hollow cylinder that defines an inner passageway that receives the turbocharger shaft 40. The flinger sleeve 44 is fixed to the turbocharger shaft 40, for example by being clamped in the axial direction between the compressor wheel 38 and the thrust bearing assembly 42. In one embodiment, a first end of the flinger sleeve 44 abuts a hub of the compressor wheel 38, and an opposed second end of the flinger sleeve 44 abuts the thrust washer sub-assembly 46. It should be appreciated that the outer surface of the second end includes radially-outwardly protruding flanges or arms 47 that fling fluid clear of piston rings (not shown) surrounding the turbocharger shaft 40, whereby fluid leakage is reduced.

[0020] The thrust washer sub-assembly 46 transfers shaft axial loads to the thrust bearing 48. The thrust washer sub-assembly 46 includes a first thrust portion or washer 50, a second thrust portion or washer 52, and a cylindrical washer spacer 54. Each of the first thrust washer 50, the second thrust washer 52, and the thrust bearing 48 are disposed about the turbocharger shaft 40. The thrust bearing 48 is disposed between the first and second thrust washers 50 and 52, respectively. Each of the first thrust washer 50 and second thrust washer 52 are a thin, flat or planar plate having a center through-opening 56 and a peripheral edge 58 that defines a circular profile. One side of each thrust washer 50, 52 defines an inward face 60, or "thrust face" that abuts the washer spacer 54 and the thrust bearing 48. Another side of each thrust washer 50, 52 opposed to the inward face 60 defines an outward face 62. The outward face 62 of the first thrust washer 50 abuts the flinger sleeve 44, and the outward face 62 of the second thrust washer 52 abuts a shoulder 64 of the turbocharger shaft 40. The thrust washers 50 and 52 are made of a metal material such as steel.

[0021] The washer spacer 54 is formed of a metal material such as steel, and has an inner diameter dimensioned to receive the turbocharger shaft 40 therein with minimal clearance. The washer spacer 54 also includes opposed axial-end faces 66, 68. The washer spacer 54 is interposed between the first and second thrust washers 50 and 52, and serves to maintain a predetermined axial spacing between the first and second thrust washers 50 and 52. In particular, the axial-end faces 66, 68 abut the respective inward face 60 of each of the first and second thrust washers 50 and 52. Thus, the axial load, due to clamping the compressor wheel 38 against the shaft shoulder 64, is transferred from the washer spacer 54 to the respective thrust washers 50 and 52. In one embodiment, the washer spacer 54 may be a separate washer spacer. In another embodiment, the washer spacer 54 may be integrated with either the finger sleeve 54 or thrust washer 52 or part of both.

[0022] In the illustrated embodiment, the thrust washer sub-assembly 46 includes the first thrust washer 50, the second thrust washer 52 and the washer spacer 54 that are formed separately, and then assembled with the turbocharger shaft 40 in the above-described configuration at the time of manufacture of the turbocharger 20. However, in other embodiments, the first and second thrust washers 50 and 52 and the washer spacer 54 are pre- assembled into the above-described thrust washer sub-assembly 46 prior to building the turbocharger 20. Providing the first and second thrust washers 50 and 52 and the washer spacer 54 as a pre-assembled unit ensures that these each of these components are assembled in the correct orientation (for example, with the respective thrust faces 60 facing the washer spacer 54). In addition, any adhesive used, for instance, to hold the components in the pre-assembled configuration, would only be needed until the thrust washer sub-assembly 46 had been assembled with the turbocharger 20. Thereafter, a rotor clamping load would retain the thrust washer sub-assembly 46 in the desired configuration. In still other embodiments, the first and second thrust washers 50 and 52, respectively, and the washer spacer 54 are formed as a single, monolithic element that can be assembled as a unit with the turbocharger shaft 40 at the time of manufacture of the turbocharger 20.

[0023] The thrust bearing 48 is a flat or planar plate and includes a body 70 having a first bearing surface 72 facing the first thrust washer 50 and a second bearing surface 74 facing opposite the first bearing surface 72 and facing the second thrust washer 52. The first bearing surface 72 and the first thrust washer 50 cooperate to define a first gap 76. The washer spacer 54 has an outward surface 77 and the second bearing surface 74 and the second thrust washer 52 cooperate to define a second gap 78. The thrust bearing 48 defines a fluid passage 80 for delivering fluid such as oil to the turbocharger shaft 40 and the first and second bearing surfaces 72 and 74 via the first and second gaps 76 and 78, respectively. In one embodiment, the fluid passage 80 extends radially and axially into the body 70 at an angle. The thrust bearing 48 also includes a seal 82 extending radially from the body 70 toward the washer spacer 54. The seal cooperates with a protrusion on the washer spacer 54 to define a third gap 83. It should be appreciated that the seal 82 is formed by an annular groove 84 extending radially into a bottom of the thrust bearing 48 to define different radial clearances between the seal 82 and the bottom of the thrust bearing 48.

[0024] The thrust bearing 48 is supported on the outer surface 77 of the washer spacer 54. The thrust bearing 48 is stationary and held against the bearing housing 26. The thrust bearing 48 has an anti-rotation feature (not shown). For example, the thrust bearing 48 may be pegged to prevent rotation relative to the bearing housing 26 and the thrust washer sub assembly 46. The thrust bearing 48 is large relative to the first and second thrust washers 50 and 52, respectively. It should be appreciated that axial loads of the turbocharger shaft 40 are transmitted to the thrust bearing 48 via the thrust face 60 of the respective thrust washers 50, 52.

[0025] The thrust bearing assembly 42 also includes dynamic seal between the seal 82 of the thrust bearing 48 and another component of the turbocharger 20 (e.g. one of the first and second thrust washers 50, 52, or a sleeve (not shown) or washer spacer 54 disposed about the turbocharger shaft 40) when thrust load is applied to the first bearing surface 72 of the thrust bearing 48. The application of thrust load to the first bearing surface 72 reduces a distance or clearance of the third gap 83 between the seal 82 of the thrust bearing 48 and the other component such that fluid, for example oil, does not readily flow beyond the dynamic seal. Specifically, the dynamic seal limits fluid flow to the second gap 78 such that fluid flows at least as readily to the first gap 76 as fluid flows to the second gap 78. As such, when thrust load is applied to the first bearing surface 72 of the thrust bearing 48, thereby decreasing the width of the first gap 76, the dynamic seal ensures that fluid still flows readily to the first gap 76. In one embodiment, the first gap 76 is larger than the third gap 83 and the third gap 83 is larger than the second gap 76. For example, the first gap 76 may be approximately 0.05 millimeters to approximately 0.08 millimeters, the second gap 78 may be approximately 0.005 millimeters to approximately 0.02 millimeters and the third gap 83 may be approximately 0.01 millimeters to 0.05 millimeters. It should be appreciated that the first gap 76 is typically larger than the second gap 78.

[0026] The turbocharger 20 includes a lubrication system (not shown) for the turbocharger journal bearings and the thrust bearing assembly 42 in the bearing housing 26. In the turbocharger 20 illustrated in FIG. 1, the thrust bearing 48 is also a hydrodynamic or fluid film type of bearing. In this configuration, the stationary thrust bearing 48 is fed fluid such as oil from a fluid gallery (not shown) to feed the bearing 48. The fluid is driven into a wedge shape by the relative motion of the thrust washer 50 and the thrust washer area of the flinger sleeve 44, which rotates along with the turbocharger shaft 40, against a static thrust ramp and pad. The thrust bearing 48 controls the axial position of the rotating assembly. It should be appreciated that, for an exemplary 76 mm turbine wheel—sized turbocharger, the fluid flow is provided at a rate of about 4200 to 6200 grams per minute.

[0027] In another embodiment illustrated in Figure 4, the outer surface 77 of the washer spacer 54 may extend axially relative to the longitudinal axis A and a bottom surface 86 of the thrust bearing 48 may have a chamfered or angled surface 79 on the load bearing side adjacent the second gap 78. In yet another embodiment illustrated in Figure 5, the bottom surface 86 of the washer spacer 54 may extend axially relative to the longitudinal axis A and the outer surface 77 of the washer spacer 54 may be chamfered or angled relative to the longitudinal axis A. In a further embodiment illustrated in Figure 6, the outer surface 77 of the washer spacer 54 may extend axially relative to the longitudinal axis A and the thrust bearing 48 may have the chamfered or angled surface 79 on the unloaded bearing side adjacent the first gap 76 with a mating or parallel surface on either the thrust bearing spacer 54 or flinger sleeve 44. It should be appreciated that the embodiments of Figures 4-6 provide a biased chamfer along a spacer/thrust bearing interface for biased thrust bearing fluid flow.

[0028] Referring to Figure 7, in still another embodiment, the thrust bearing assembly 42 eliminates the first washer 50. In this embodiment, the arm 47 of the flinger sleeve 44 is the first thrust portion that forms the first gap 76 with the thrust bearing 48 such that a compressor direction axial thrust will close the second gap 78 to a first predetermined amount such as five microns (0.005 mm) and open the first gap 76 to a second predetermined amount such as sixty - five microns (0.065 mm). The third gap 83 will also close a third predetermined amount such as five microns (0.005 mm) forcing more fluid to the loaded thrust surface of the second gap 78. It should be appreciated that the third gap 83 should be relatively small, for example near line to line radially. It should also be appreciated that the non-sealing surface between the flinger sleeve 44and thrust bearing 48 should be greater than the second predetermined amount. It should be further appreciated that the flinger sleeve 44 also forms the washer spacer instead of a separate washer spacer 54.

[0029] Referring to Figures 8 and 9, in a further embodiment, the thrust bearing assembly 42 eliminates the first washer 50. In this embodiment, the arm 47 of the flinger sleeve 44 is the first thrust portion that forms the first gap 76 with the thrust bearing 48. As illustrated, the first gap 76 has an axial distance C2, the second gap 78 has an axial distance CI, and the third gap 83 has an axial distance C3. In a first operational position of Figure 8, the application of a compressor direction thrust load 90 to the first washer 52 reduces the axial distance CI of the second gap 78, opens the axial distance C2 of the first gap 76, and reduces the axial distance C3 of the third gap 83 between the seal 82 of the thrust bearing 48 and the washer spacer 54 keeping fluid on top of the washer spacer 54. For example, the axial distance of CI is less than the axial distance of C2 and the axial distance of C3 is less than the axial distance of C2 and greater than the axial distance of CI. In one embodiment, C2 may be approximately 0.05 millimeters to approximately 0.08 millimeters, CI may be approximately 0.005 millimeters to approximately 0.02 millimeters, and C3 may be approximately 0.01 millimeters to 0.05 millimeters. In a second operational position of Figure 9, the application of a turbine direction thrust load 92 to the finger sleeve 44 reduces the axial distance C2 of the first gap 76, opens the axial distance CI of the second gap 78, and opens the axial distance C3 of the third gap 83. For example, the axial distance of C3 is greater than the axial distance of CI and the axial distance of C2. It should be appreciated that the gaps 76, 78, and 83 are slightly exaggerated in Figures 8 and 9.

[0030] Accordingly, the turbocharger 20 of the present invention provides a thrust bearing assembly 42 having a dynamic seal that reduces mechanical losses associated with conventional thrust bearing assemblies. The turbocharger 20 of the present invention has the thrust bearing assembly 42 with improved resistance to wear compared to conventional thrust bearing assemblies because the load capacity is increased. The turbocharger 20 of the present invention provides the thrust bearing assembly 42 that reduces lubricant flow towards the compressor piston ring seal (not shown), thereby reducing the risk of leakage to a compressor side of the turbocharger 20.

[0031] The present invention has been described in an illustrative manner. It is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation.

[0032] Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described.

[0033] Although the present invention is defined in the attached claims, it is to be understood that the invention can alternatively also be defined in accordance with the following embodiments:

1. A thrust bearing assembly for a turbocharger comprising:

a first thrust portion disposed on a turbocharger shaft of the turbocharger;

a second thrust portion disposed on the turbocharger shaft and spaced axially from the first thrust portion;

a washer spacer disposed on the turbocharger shaft axially between the first thrust portion and the second thrust portion; and

a thrust bearing being disposed axially between the first thrust portion and the second thrust portion and about the washer spacer, the thrust bearing including a first bearing surface to define a first gap with the first thrust portion, a second bearing surface that is opposed to the first bearing surface to define a second gap with the second thrust portion, and a seal extending toward the washer spacer to define a third gap with the washer spacer, the thrust bearing having a fluid passage extending to the washer spacer to provide fluid to the first gap and the second gap, wherein the thrust bearing and the washer spacer cooperate to define a dynamic seal to reduce lubricant flow to the second bearing surface when thrust load is applied to the first bearing surface of the thrust bearing.

2. A thrust bearing assembly as set forth in embodiment 1 wherein a first thrust portion is either one of a first thrust washer and a flinger sleeve.

3. A thrust bearing assembly as set forth in embodiment 1 or embodiment 2 wherein a second thrust portion is a second thrust washer.

4. A thrust bearing assembly as set forth in any one of embodiments 1-3 wherein a washer spacer is either one of a separate washer spacer and a washer spacer integrated into a flinger sleeve.

5. A thrust bearing assembly as set forth in any one of embodiments 1-4 wherein each of a first thrust washer and a second thrust washer is mounted on the turbocharger shaft and includes a first face and a second face that is opposed to the first face.

6. A thrust bearing assembly as set forth in any one of embodiments 1-5 wherein a washer spacer has a first end that abuts a first face of a first thrust washer and a second end opposed to the first end, the second end abutting a first face of a second thrust washer.

7. A thrust bearing assembly as set forth in any one of embodiments 1-6 wherein a thrust bearing has a bottom surface at a radial depth less than a radial depth of the seal.

8. A thrust bearing assembly as set forth in any one of embodiments 1-6 wherein a thrust bearing has a chamfered surface on a bottom surface thereof on a load bearing side adjacent the second gap.

9. A thrust bearing assembly as set forth in embodiment 8 wherein a washer spacer has an outer surface that extends axially relative to a longitudinal axis of the turbocharger shaft.

10. A thrust bearing assembly as set forth in any one of embodiments 1-6 wherein a thrust bearing has a bottom surface that extends axially relative to a longitudinal axis of the turbocharger shaft.

11. A thrust bearing assembly as set forth in embodiment 10 wherein a washer spacer has an outer surface that extends axially at an angle relative to the longitudinal axis of the turbocharger shaft. 12. A thrust bearing assembly as set forth in any one of embodiments 1-6 wherein a thrust bearing has a chamfered surface on a bottom surface thereof on an unloaded bearing side adjacent the first gap.

13. A thrust bearing assembly as set forth in embodiment 12 wherein a washer spacer has an outer surface that extends axially relative to a longitudinal axis of the turbocharger shaft and includes a chamfered surface that is parallel to a chamfered surface of a thrust bearing.

14. A turbocharger comprising:

a turbine wheel to receive exhaust gas from an internal combustion engine;

a turbocharger shaft coupled to and rotatable by the turbine wheel, the turbocharger shaft extending along a longitudinal axis;

a compressor wheel coupled to and rotatable by the turbocharger shaft for compressing air to be delivered to the internal combustion engine;

a thrust bearing assembly on the turbocharger shaft to provide axial support for the turbocharger shaft; and

the thrust bearing assembly comprising a first thrust washer and a second thrust washer, each of the first thrust washer and the second thrust washer being mounted on the turbocharger shaft and including a first face, and a second face that is opposed to the first face, a washer spacer disposed on the turbocharger shaft axially between the first thrust washer and the second thrust washer, the washer spacer having a first end that abuts the first face of the first thrust washer and a second end opposed to the first end, the second end abutting the first face of the second thrust washer, and a thrust bearing being disposed axially between the first thrust washer and the second thrust washer and about the washer spacer, the thrust bearing including a first bearing surface to define a first gap with the first face of the first thrust washer, a second bearing surface that is opposed to the first bearing surface to define a second gap with the first face of the second thrust washer, and a seal extending toward the thrust bearing spacer to define a third gap with the washer spacer, the thrust bearing having a fluid passage extending to the washer spacer to provide fluid to the first gap and the second gap, wherein the thrust bearing and the washer spacer cooperate to define a dynamic seal to reduce lubricant flow to the second bearing surface when thrust load is applied to the first bearing surface of the thrust bearing.

15. A turbocharger as set forth in embodiment 14 wherein a thrust bearing has a bottom surface at a radial depth less than a radial depth of the seal. 16. A turbocharger as set forth in embodiment 14 or embodiment 15 wherein a thrust bearing has a chamfered surface on a bottom surface thereof on a load bearing side adjacent the second gap and a washer spacer has an outer surface that extends axially relative to a longitudinal axis of the turbocharger shaft.

17. A turbocharger as set forth in any one of embodiments 14-16 wherein a thrust bearing has a bottom surface that extends axially relative to a longitudinal axis of the turbocharger shaft and a washer spacer has an outer surface that extends axially at an angle relative to the longitudinal axis of the turbocharger shaft.

18. A turbocharger as set forth in any one of embodiments 14-17 wherein a thrust bearing has a chamfered surface on a bottom surface thereof on an unloaded bearing side adjacent the first gap and a washer spacer has an outer surface that extends axially relative to a longitudinal axis of the turbocharger shaft and includes a chamfered surface that is parallel to a chamfered surface of a thrust bearing.

19. A turbocharger comprising:

a turbine wheel to receive exhaust gas from an internal combustion engine;

a turbocharger shaft coupled to and rotatable by the turbine wheel, the turbocharger shaft extending along a longitudinal axis;

a compressor wheel coupled to and rotatable by the turbocharger shaft for compressing air to be delivered to the internal combustion engine;

a thrust bearing assembly on the turbocharger shaft to provide axial support for the turbocharger shaft; and

the thrust bearing assembly comprising a flinger sleeve having a first thrust portion disposed on a turbocharger shaft of the turbocharger;

a second thrust portion disposed on the turbocharger shaft and spaced axially from the first thrust portion;

said flinger sleeve having a washer spacer disposed on the turbocharger shaft axially between the first thrust portion and the second thrust portion; and

a thrust bearing being disposed axially between the first thrust portion and the second thrust portion and about the washer spacer, the thrust bearing including a first bearing surface to define a first gap with the first thrust portion, a second bearing surface that is opposed to the first bearing surface to define a second gap with the second thrust portion, and a seal extending toward the washer spacer to define a third gap with the washer spacer, the thrust bearing having a fluid passage extending to the washer spacer to provide fluid to the first gap and the second gap, wherein the thrust bearing and the washer spacer cooperate to define a dynamic seal to reduce lubricant flow to the second bearing surface when thrust load is applied to the first bearing surface of the thrust bearing.

20. A turbocharger as set forth in embodiment 19 wherein a thrust bearing has a bottom surface at a radial depth less than a radial depth of the seal.

21. A turbocharger as set forth in embodiment 19 or embodiment 20 wherein a thrust bearing has a chamfered surface on a bottom surface thereof on a load bearing side adjacent the second gap and a washer spacer has an outer surface that extends axially relative to a longitudinal axis of the turbocharger shaft.

22. A turbocharger as set forth in any one of embodiments 19-21 wherein a thrust bearing has a bottom surface that extends axially relative to a longitudinal axis of the turbocharger shaft and a washer spacer has an outer surface that extends axially at an angle relative to the longitudinal axis of the turbocharger shaft.

23. A turbocharger as set forth in any one of embodiments 19-22 wherein a thrust bearing has a chamfered surface on a bottom surface thereof on an unloaded bearing side adjacent the first gap and a washer spacer has an outer surface that extends axially relative to a longitudinal axis of the turbocharger shaft and includes a chamfered surface that is parallel to a chamfered surface of a thrust bearing.