WO2014143876A1

WO2014143876A1 - Bearing cage lubrication architecture

Info

Publication number: WO2014143876A1
Application number: PCT/US2014/028033
Authority: WO
Inventors: David L. Motto; Brian P. Cigal
Original assignee: United Technologies Corporation
Priority date: 2013-03-15
Filing date: 2014-03-14
Publication date: 2014-09-18

Abstract

A bearing assembly includes an inner race with an inner race oil passage and a bearing cage with a bearing cage oil passage in fluid communication with the inner race oil passage.

Description

BEARING CAGE LUBRICATION ARCHITECTURE

This application claims priority to U.S. Patent Appln. No. 61/786,894 filed March 15,

2013.

BACKGROUND

[0001] The present disclosure relates to rolling-element bearings, in particular for use in high speed applications such as, for example, in gas turbine engines.

[0002] A rolling-element bearing often includes an inner race, an outer race and an array of rolling elements such as balls, needles or rollers arranged within a bearing cage between the races for rotation at epicyclic speed. During rotation of the bearing, the rolling elements are under load and push against the bearing cage and rotate the bearing cage such that the bearing cage in turn pushes those rolling elements which are not under load. The bearing cage may tend not to remain concentric in the bearing but instead may tend to move in an eccentric path due to dynamic imbalance.

[0003] During rotation of the bearing, centrifugal force maintains the rolling elements in firm contact with the outer race so that the rolling elements tend to run at the outer race speed with any skid thereby more likely to occur between the rolling elements and the inner race. Centrifugal effects may also complicate retention of lubricating oil between the bearing cage and the rolling elements.

SUMMARY [0004] A bearing assembly according to one disclosed non-limiting embodiment of the present disclosure includes an inner race with an inner race oil passage and a bearing cage with a bearing cage oil passage in fluid communication with the inner race oil passage.

[0005] In a further embodiment of the present disclosure, the inner race oil passage defines an inner race passage axis and the bearing cage oil passage defines a bearing cage passage axis, and the bearing cage passage axis intersects the inner race passage axis.

[0006] In a further embodiment of any of the foregoing embodiments of the present disclosure, the bearing cage passage axis is angled with respect to the inner race passage axis.

[0007] In a further embodiment of any of the foregoing embodiments of the present disclosure, the bearing cage passage axis is angled at about 30-60 degrees with respect to the inner race passage axis.

[0008] In a further embodiment of any of the foregoing embodiments of the present disclosure, the bearing cage oil passage is L-shaped.

[0009] In a further embodiment of any of the foregoing embodiments of the present disclosure, the bearing cage oil passage includes a flared inlet.

[0010] In a further embodiment of any of the foregoing embodiments of the present disclosure, the bearing cage oil passage includes a flared outlet.

[0011] In a further embodiment of any of the foregoing embodiments of the present disclosure, the bearing cage oil passage includes an increased diameter inlet.

[0012] In a further embodiment of any of the foregoing embodiments of the present disclosure, the bearing cage oil passage includes an increased diameter outlet. [0013] In a further embodiment of any of the foregoing embodiments of the present disclosure, the inner race oil passage defines an inner race passage axis that does not intersect a rolling element.

[0014] A bearing assembly according to another disclosed non-limiting

embodiment of the present disclosure includes an inner race with an inner race oil passage which defines a race axis, a bearing cage with a bearing cage oil passage that defines a bearing cage axis, and the bearing cage axis intersects the race axis.

[0015] In a further embodiment of any of the foregoing embodiments of the present disclosure, the bearing cage passage axis is angled with respect to the inner race passage axis.

[0016] In a further embodiment of any of the foregoing embodiments of the present disclosure, the bearing cage passage axis is angled with respect to the inner race passage axis.

[0017] In a further embodiment of any of the foregoing embodiments of the present disclosure, the bearing cage oil passage is L-shaped.

[0018] In a further embodiment of any of the foregoing embodiments of the present disclosure, the inner race oil passage defines an inner race passage axis that does not intersect a rolling element.

[0019] A method of lubricating a bearing assembly according to another disclosed non-limiting embodiment of the present disclosure includes communicating a lubricant through a bearing cage. [0020] A further embodiment of any of the foregoing embodiments of the present disclosure includes communicating the lubricant at an angle through the bearing cage with respect to an inner race passage axis in an inner race.

[0021] A further embodiment of any of the foregoing embodiments of the present disclosure includes communicating the lubricant through an L-shaped passage in the bearing cage.

[0022] A further embodiment of any of the foregoing embodiments of the present disclosure includes offsetting an outlet from an inner race passage from an inlet to a bearing cage oil passage for communicating the lubricant through the bearing cage.

[0023] A further embodiment of any of the foregoing embodiments of the present disclosure includes skewing a bearing cage oil passage for communicating the lubricant through the bearing cage.

[0024] The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, the following description and drawings are intended to be exemplary in nature and non-limiting.

BRIEF DESCRIPTION OF THE DRAWINGS [0025] Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows:

[0026] Figure 1 is a schematic cross-section of an example gas turbine engine architecture;

[0027] Figure 2 is a partial perspective section view of a bearing assembly;

[0028] Figure 3 is a longitudinal section view of a bearing assembly according to one disclosed non-limiting embodiment;

[0029] Figure 4 is a longitudinal section view of a bearing assembly according to another disclosed non-limiting embodiment;

[0030] Figure 5 is a longitudinal section view of a bearing assembly according to another disclosed non-limiting embodiment;

[0031] Figure 6 is a longitudinal section view of a bearing assembly according to another disclosed non-limiting embodiment;

[0032] Figure 7 is a face view of a bearing cage with cage oil passages skewed according to another disclosed non-limiting embodiment; and

[0033] Figure 8 is a face view of a bearing cage with cage oil passages radially directed according to another disclosed non-limiting embodiment.

DETAILED DESCRIPTION

[0034] Figure 1 schematically illustrates a gas turbine engine 20. The gas turbine engine 20 is disclosed herein as a two-spool turbofan that generally incorporates a fan section 22, a compressor section 24, a combustor section 26 and a turbine section 28. Alternative engine architectures might include an augmentor section and exhaust duct section (not shown) among other systems or features. The fan section 22 drives air along a bypass flowpath while the compressor section 24 drives air along a core flowpath for compression and communication into the combustor section 26 then expansion thru the turbine section 28. Although depicted as a turbofan in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engines such as a low bypass augmented turbofan, turbojets, turboshafts, and three-spool (plus fan) turbofans wherein an intermediate spool includes an intermediate pressure compressor ("IPC") between a Low Pressure Compressor ("LPC") and a High Pressure Compressor ("HPC"), and an intermediate pressure turbine ("IPT") between the high pressure turbine ("HPT") and the Low pressure Turbine ("LPT").

[0035] The engine 20 generally includes a low spool 30 and a high spool 32 mounted for rotation about an engine central longitudinal axis A relative to an engine case structure 36 via several bearing compartments 38. The low spool 30 generally includes an inner shaft 40 that interconnects a fan 42, a low pressure compressor 44 ("LPC") and a low pressure turbine 46 ("LPT"). The inner shaft 40 drives the fan 42 directly or thru a geared architecture 48 to drive the fan 42 at a lower speed than the low spool 30. An exemplary reduction transmission is an epicyclic transmission, namely a planetary or star gear system.

[0036] The high spool 32 includes an outer shaft 50 that interconnects a high pressure compressor 52 ("HPC") and high pressure turbine 54 ("HPT"). A combustor 56 is arranged between the HPC 52 and the HPT 54. The inner shaft 40 and the outer shaft 50 are concentric and rotate about the engine central longitudinal axis "A" which is collinear with their longitudinal axes.

[0037] Core airflow is compressed by the LPC 44 then the HPC 52, mixed with fuel and burned in the combustor 56, then expanded over the HPT 54 and the LPT 46. The turbines 54, 46 rotationally drive the respective low spool 30 and high spool 32 in response to the expansion. The main engine shafts 40, 50 are supported at a plurality of points by the bearing compartments 38. It should be understood that various bearing compartments 38 at various locations may alternatively or additionally be provided.

[0038] In one example, the gas turbine engine 20 is a high-bypass geared aircraft engine with a bypass ratio greater than about six (6: 1). The geared architecture 48 can include an epicyclic gear train, such as a planetary gear system or other gear system. The example epicyclic gear train has a gear reduction ratio of greater than about 2.3:1, and in another example is greater than about 2.5:1. The geared turbofan enables operation of the low spool 30 at higher speeds which can increase the operational efficiency of the LPC 44 and LPT 46 to render increased pressure in a relatively few number of stages. [0039] A pressure ratio associated with the LPT 46 is pressure measured prior to the inlet of the LPT 46 as related to the pressure at the outlet of the LPT 46 prior to an exhaust nozzle of the gas turbine engine 20. In one non-limiting embodiment, the bypass ratio of the gas turbine engine 20 is greater than about ten (10:1), the fan diameter is significantly larger than that of the LPC 44, and the LPT 46 has a pressure ratio that is greater than about five (5:1). It should be understood, however, that the above parameters are only exemplary of one embodiment of a geared architecture engine and that the present disclosure is applicable to other gas turbine engines including direct drive turbofans, where the rotational speed of the fan 42 is the same (1 :1) of the LPC 44.

[0040] In one example, a significant amount of thrust is provided by the bypass flow path due to the high bypass ratio. The fan section 22 of the gas turbine engine 20 is designed for a particular flight condition - typically cruise at about 0.8 Mach and about 35,000 feet. This flight condition, with the gas turbine engine 20 at its best fuel consumption, is also known as bucket cruise Thrust Specific Fuel Consumption (TSFC). TSFC is an industry standard parameter of fuel consumption per unit of thrust.

[0041] Fan Pressure Ratio is the pressure ratio across a blade of the fan section 22 without the use of a Fan Exit Guide Vane system. The relatively low Fan Pressure Ratio according to one example gas turbine engine 20 is less than 1.45. Low Corrected Fan Tip Speed is the actual fan tip speed divided by an industry standard temperature correction of ("Tram" / 518.7)⁰'⁵ in which "Tram" represents about 0.0 degrees F due to the flight velocity of about 0.8 Mach. The Low Corrected Fan Tip Speed according to one example gas turbine engine 20 is less than about 1150 fps (351 m/s).

[0042] With reference to Figure 2, the bearing compartments 38 and the geared architecture 48, for example, may include one or more bearing assemblies 60. Each bearing assembly 60 typically includes an outer race 62, an inner race 64 and an array of rolling elements 66 held within a respective bearing cage 68 about a bearing axis of rotation B. It should be appreciated that although balls are shown as the rolling elements 66, various other rolling elements such as pins and rollers will also benefit herefrom. Furthermore, although the bearing compartments 38 and the geared architecture 48 are disclosed locations for the bearing assembly 60, the bearing assembly 60 disclosed herein is not limited to only such uses.

[0043] With reference to Figure 3, the inner race 64 includes a multiple of first oil passages 70 and a multiple of second oil passages 72 each along a respective first and second race passage axis 74, 76 which extend radially from the bearing axis of rotation B. The multiple of first oil passages 70 are generally parallel to a respective first face 78 and the multiple of second oil passages 72 are generally parallel to a respective second face 80 of the inner race 64. The multiple of first oil passages 70 and a multiple of second oil passages 72 flank the rolling elements 66. That is, the first and second race axis 74, 76 do not intersect the rolling elements 66 but do intersect the bearing cage 68.

[0044] The multiple of first oil passages 70 and the multiple of second oil passages 72 intersect a respective multiple of first bearing cage oil passages 82 and a multiple of second bearing cage oil passages 84 within the bearing cage 68. Each of the multiple of first bearing cage oil passages 82 and each of the multiple of second bearing cage oil passages 84 are defined along respective first and second bearing cage oil passages axes 86, 88 that are angled with respect to the first and second race axis 74, 76. That is, the first and second bearing cage oil passages axes 86, 88 intersect the respective first and second race axis 74, 76.

[0045] In one disclosed non-limiting embodiment, the first and second bearing cage oil passages axes 86, 88 define an angle between about 30-60 degrees to direct oil toward the rolling elements 66. In another disclosed non-limiting embodiment, the first and second bearing cage oil passages axes 86, 88 are L-shaped to direct oil toward the rolling elements 66 (Figure 4).

[0046] A bearing cage oil passage inlet 90, 92 of the first and second bearing cage oil passages 82, 84 need not align specifically with a race oil passage outlet 94, 96 to the first and second oil passages 70, 72. That is, the bearing cage oil passage inlet 90, 92 may be axially offset along the bearing axis B with respect to the associated race oil passage outlet 94, 96. In one disclosed non-limiting embodiment, the bearing cage oil passage inlet 90, 92 are offset outward toward the respective first and second face 78, 80.

[0047] Oil from the multiple of first oil passages 70 and the multiple of second oil passages 72 is directed to the bearing cage oil passage inlet 90, 92 and thence to the rolling elements 66. The bearing cage oil passage inlet 90, 92 and the bearing cage oil passage outlet 94, 96 of the first and second bearing cage oil passages 82, 84 may be flared 102 (Figure 5) and/or of an increased diameter 104 (Figure 6) to facilitate oil flow. Furthermore, the first and second bearing cage oil passages axes 86, 88 may be raked to define a pitch with respect to the bearing axis B to further facilitate oil flow (Figure 7). That is, the first and second bearing cage oil passages axes 86, 88 maybe skewed and not radially arranged with respect to the bearing axis B (Figure 8). It should be appreciated that various combinations maybe provided.

[0048] Although the different non-limiting embodiments have specific illustrated components, the embodiments of this invention are not limited to those particular

combinations. It is possible to use some of the components or features from any of the non- limiting embodiments in combination with features or components from any of the other non- limiting embodiments.

[0049] It should be understood that relative positional terms such as "forward," "aft," "upper," "lower," "above," "below," and the like are with reference to the normal operational attitude of the vehicle and should not be considered otherwise limiting.

[0050] It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom.

[0051] Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure.

[0052] The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.

Claims

CLAIMS What is claimed is:

1. A bearing assembly comprising:

an inner race with an inner race oil passage; and

a bearing cage with a bearing cage oil passage in fluid communication with said inner race oil passage.

2. The assembly as recited in claim 1, wherein said inner race oil passage defines an inner race passage axis and said cage oil passage defines a bearing cage passage axis, said cage passage axis intersects said inner race passage axis.

3. The assembly as recited in claim 2, wherein said cage passage axis is angled with respect to said inner race passage axis.

4. The assembly as recited in claim 2, wherein said cage passage axis is angled at about 30-60 degrees with respect to said inner race passage axis.

5. The assembly as recited in claim 1, wherein said cage oil passage is L-shaped.

6. The assembly as recited in claim 1, wherein said cage oil passage includes a flared inlet.

7. The assembly as recited in claim 1, wherein said cage oil passage includes a flared outlet.

8. The assembly as recited in claim 1, wherein said cage oil passage includes an increased diameter inlet.

9. The assembly as recited in claim 1, wherein said cage oil passage includes an increased diameter outlet.

10. The assembly as recited in claim 1, wherein said inner race oil passage defines an inner race passage axis that does not intersect a rolling element.

11. A bearing assembly comprising:

an inner race with an inner race oil passage which defines a race axis; and a bearing cage with a bearing cage oil passage that defines a bearing cage axis, said cage axis intersects said race axis.

12. The assembly as recited in claim 11, wherein said cage passage axis is angled with respect to said inner race passage axis.

13. The assembly as recited in claim 11, wherein said cage passage axis is angled with respect to said inner race passage axis.

14. The assembly as recited in claim 11, wherein said cage oil passage is L-shaped.

15. The assembly as recited in claim 1, wherein said inner race oil passage defines an inner race passage axis that does not intersect a rolling element.

16. A method of lubricating a bearing assembly, comprising: communicating a lubricant through a bearing cage.

17. The method as recited in claim 16, further comprising communicating the lubricant at an angle through the bearing cage with respect to an inner race passage axis in an inner race.

18. The method as recited in claim 16, further comprising communicating the lubricant through an L-shaped passage in the bearing cage.

19. The method as recited in claim 16, further comprising offsetting an outlet from an inner race passage from an inlet to a bearing cage oil passage for communicating the lubricant through the bearing cage.

20. The method as recited in claim 16, further comprising skewing a bearing cage oil passage for communicating the lubricant through the bearing cage.