Cooling for bearing and race assemblies

Abstract

A system and method for cooling a race and bearing assembly comprises a shaft for a turbine, and at least one channel configured in the shaft, wherein the shaft is configured to interface with a race and bearing assembly and the channels are configured to allow air to flow therethrough.

Description

Attorney Docket No. BEEHI-1038PCT Patent ApplicationCOOLING FOR BEARING AND RACE ASSEMBLIESCROSS REFERENCE TO RELATED PATENT APPLICATION

[0001] This application claims the priority and benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application Serial No. 63 / 696,622 filed September 19, 2024, entitled “COOLING FOR BEARING AND RACE ASSEMBLIES.” U.S. Provisional Patent Application Serial Number 63 / 696,622 is herein incorporated by reference in its entirety.TECHNICAL FIELD

[0002] Embodiments are related to bearings and races. Embodiments are further related to cooling bearing and race assemblies. Embodiments are further related to fabrication techniques. Embodiments are related to manufacturing methods and processes. Embodiments are further related to turbomachinery. Embodiments are directed to cooling grooves for bearing race assembles. Embodiments are further directed to air cooling configurations for flowing air below and around bearings.BACKGROUND

[0003] Bearings are ubiquitous, with applications in essentially every modern technology. In particular, physical systems that involve spinning or rotating parts make use of bearings to facilitate motion.

[0004] Bearings can be used to provide free linear movement or rotation around an axis. Bearings are often designed to reduce friction between moving parts so that the associated parts can move at high speed or at high RPM.

[0005] One exemplary application of bearings is in turbomachinery. Turbomachinery can be understood to include devices that transfer energy between a rotor and fluid (e.g. ambientAttorney Docket No. BEEHI-1038PCT Patent Application air). Turbines are an example of turbomachinery that transfers energy from a fluid to a rotor, facilitated by bearings that minimize friction to improve efficient energy transfer.

[0006] For many applications, including aerospace applications, conventional cooling techniques for bearings use oil to lubricate and remove heat.

[0007] For example, some greased bearings have fluids (e.g. fuel, or oil) impinging on them to help remove heat. High speed oil lubricated bearings may have lubrication which flows from up through the bearing. In these types of systems, cooling / lubricating oil is provided directly into the bearing.

[0008] However, there are numerous drawbacks to oil based cooling for bearings. For example, in some cases, such solutions require separate pumps, sumps, oil distribution assemblies, and / or additional space where formfactor is critically important.

[0009] Accordingly, there is a need in the art for improved race and bearing assembly cooling, as disclosed in the embodiments herein.Attorney Docket No. BEEHI-1038PCT Patent ApplicationBRIEF SUMMARY

[0010] The following summary is provided to facilitate an understanding of some of the innovative features unique to the embodiments disclosed and is not intended to be a full description. A full appreciation of the various aspects of the embodiments can be gained by taking the entire specification, claims, drawings, and abstract as a whole.

[0011] It is, therefore, one aspect of the disclosed embodiments to provide improved bearing and race cooling.

[0012] It is another aspect of the disclosed embodiments to provide air cooling for bearing and race assemblies.

[0013] It is another aspect of the disclosed embodiments to provide air flow channels for bearing and race cooling.

[0014] It is another aspect of the disclosed embodiments to provide manufacturing methods for bearing and race assemblies including shafts with cooling channels.

[0015] It is another aspect of the disclosed embodiments to provide means for airflow around bearing and race assemblies.

[0016] It is another aspect of the disclosed embodiments to provide methods and systems for cooling race and bearing assemblies via channels in a shaft associated with the assembly, which allow cooling air to pass directly under the bearing race to remove heat.

[0017] For example, in an embodiment, a bearing cooling system comprises a shaft and at least one channel formed in the shaft, wherein the shaft is configured to interface with a race and bearing assembly. In an embodiment, the at least one channel is formed on an external surface of the shaft. In an embodiment, the channels are configured to allow fluid to flow therethrough. In an embodiment, the fluid comprises air. In an embodiment, the bearing cooling system further comprises an air chamber formed by a housing associated with the turbine. In an embodiment, the at least one channel further comprises two sidewalls formedAttorney Docket No. BEEHI-1038PCT Patent Application in the shaft and a bottom surface nominally perpendicular to the two sidewalls. In an embodiment, the at least one channel further comprises two sidewalls meeting nominally at a trough, forming a “v” shape. In an embodiment, the at least one channel further comprises a tubular shape. In an embodiment, the at least one channel further comprises a plurality of channels. In an embodiment, the plurality of channels are equally spaced around a diameter of the shaft. In an embodiment, the shaft is configured for a turbomachine. In an embodiment, the turbomachine comprises a turbine.

[0018] In an embodiment, a cooling system for a turbomachine comprises a race and bearing assembly, a shaft, and a plurality of channels formed in an external surface of the shaft, wherein the shaft is configured to interface with the race and bearing assembly. In an embodiment, the plurality of channels are configured to allow fluid to flow proximate to the race and bearing assembly. In an embodiment the cooling system for a turbomachine further comprises an air chamber formed by a housing associated with the turbine. In an embodiment, each of the plurality of channels further comprise two sidewalls formed in the shaft and a bottom surface nominally perpendicular to the two sidewalls. In an embodiment, the plurality of channels are equally spaced around a diameter of the shaft.

[0019] In an embodiment, a method for cooling a bearing and race assembly comprises configuring a shaft to interface with the bearing and race assembly, forming a plurality of channels in the shaft, and flowing a fluid through the plurality of channels in the shaft. In an embodiment, the method for cooling a bearing and race assembly further comprises creating a pressure differential in an air chamber formed by a housing associated with the turbine, the pressure differential driving the fluid to flow through the plurality of channels in the shaft. In an embodiment, the plurality of channels are equally spaced around a diameter of the shaft.Attorney Docket No. BEEHI-1038PCT Patent ApplicationBRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying figures, in which like reference numerals refer to identical or functionally similar elements throughout the separate views and which are incorporated in and form a part of the specification, further illustrate the embodiments and, together with the detailed description, serve to explain the embodiments disclosed herein.

[0021] FIG. 1 depicts a turbine, with air cooling a bearing, in accordance with the disclosed embodiments;

[0022] FIG. 2 depicts an exploded view of a shaft with channels for air cooling, in accordance with the disclosed embodiments;

[0023] FIG. 3 depicts a diagram illustrating air flow in a channel for air cooling a bearing and race assembly, in accordance with the disclosed embodiments;

[0024] FIG. 4 depicts a diagram of another embodiment illustrating air flow in a channel for air cooling a bearing and race assembly, in accordance with the disclosed embodiments;

[0025] FIG. 5 depicts steps associated with a method for manufacturing a shaft, in accordance with the disclosed embodiments; and

[0026] FIG. 6 depicts steps associated with a method for cooling a bearing and race assembly, in accordance with the disclosed embodiments.Attorney Docket No. BEEHI-1038PCT Patent ApplicationDETAILED DESCRIPTION

[0027] The particular values and configurations discussed in the following non-limiting examples can be varied and are cited merely to illustrate one or more embodiments and are not intended to limit the scope thereof.

[0028] Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments are shown. The embodiments disclosed herein can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the embodiments to those skilled in the art. Like numbers refer to like elements throughout.

[0029] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprise" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0030] Throughout the specification and claims, terms may have nuanced meanings suggested or implied in context beyond an explicitly stated meaning. Likewise, the phrase “in one embodiment” as used herein does not necessarily refer to the same embodiment and the phrase “in another embodiment” as used herein does not necessarily refer to a different embodiment. It is intended, for example, that claimed subject matter include combinations of example embodiments in whole or in part.

[0031] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. ItAttorney Docket No. BEEHI-1038PCT Patent Application will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0032] It is contemplated that any embodiment discussed in this specification can be implemented with respect to any method, kit, reagent, or composition of the invention, and vice versa. Furthermore, compositions of the invention can be used to achieve methods of the invention.

[0033] It will be understood that particular embodiments described herein are shown by way of illustration and not as limitations of the invention. The principal features of this invention can be employed in various embodiments without departing from the scope of the invention. Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation, numerous equivalents to the specific procedures described herein. Such equivalents are considered to be within the scope of this invention and are covered by the claims.

[0034] The use of the word “a” or “an” when used in conjunction with the term “comprising” in the claims and / or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” The use of the term “or” in the claims is used to mean “and / or” unless explicitly indicated to refer to alternatives only or the alternatives are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and “and / or.” Throughout this application, the term “about” is used to indicate that a value includes the inherent variation of error for the device, the method being employed to determine the value, or the variation that exists among the study subjects.

[0035] As used in this specification and claim(s), the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive orAttorney Docket No. BEEHI-1038PCT Patent Application open-ended and do not exclude additional, unrecited elements or method steps.

[0036] The term “or combinations thereof” as used herein refers to all permutations and combinations of the listed items preceding the term. For example, “A, B, C, or combinations thereof” is intended to include at least one of: A, B, C, AB, AC, BC, or ABC, and if order is important in a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB. Continuing with this example, expressly included are combinations that contain repeats of one or more item or term, such as BB, AAA, AB, BBC, AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan will understand that typically there is no limit on the number of items or terms in any combination, unless otherwise apparent from the context.

[0037] All of the compositions and / or methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the compositions and / or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit, and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims.

[0038] The embodiments disclosed herein are directed to systems and methods for cooling race and bearing assemblies. The disclosed embodiments leverage conduction and convection to remove heat. The embodiments provide air flow under the bearing, as well as through and over the bearing, to cool the bearing. The disclosed embodiments can further minimize the conduction path to the bearing with holes or channels which allow for cooler air to flow between the bearing and hotter hardware in a turbomachine such as a turbine.

[0039] FIG. 1 illustrates a turbomachine assembly 100 in accordance with the disclosed embodiments. The figure shows the turbine 102, as well as the aft frame 104 which supports a bearing. The turbomachine assembly 100 can comprise a turbine 102 or other such device with a shaft and associated bearings. A bearing with an outer race is provided in a structure,Attorney Docket No. BEEHI-1038PCT Patent Application and an inner race supports the shaft or hardware with an integral stub shaft. The stub shaft is a subset of the turbine wheel or larger shaft; it is a smaller section where the bearing is interfacing.

[0040] FIG. 2 illustrates aspects of the disclosed embodiments. In this view a shaft 202 is shown. The bearing inner race is connected to the shaft 202. The shaft 202 can be configured to include one or more channels 204 formed in or on the external surface 216 of the shaft 202. This view shows the shaft 202 on the aft side 214 of the turbine 200. The channels 204 are configured to allow cooling air to pass directly under the bearing race to remove heat via convection. The channels 204 can comprise two sidewalls, first sidewall 206 and second sidewall 208 formed in the shaft 202, and a bottom surface 210 nominally perpendicular to the two sidewalls. In other embodiments, the channel(s) 204 can have a tubular or cylindrical cross-sectional shape, or other such shape.

[0041] The axial shoulder against which the bearing is pressed, can also be configured to be intermittent to allow for the passage of air. The blocks 212 form the intermittent shoulder the bearing pushes against. In some cases, the shaft 202 may actually be hotter than the bearing. The intermittent features further help reduce the temperature of the bearing, by reducing the contact area with a hotter shaft 202.

[0042] FIG. 3 provides further details of a system 300, in accordance with the disclosed embodiments. As illustrated, a turbine 302 is connected to a stub shaft 304, in operable relation to a tie-bolt 306 and nut 308. As illustrated, the stub shaft 304 is part of the turbine 302. However, it should be understood that, in certain embodiments, the stub shaft 304 can be a separate part that is fixed to the turbine 302.

[0043] In certain embodiments, the turbine 302 (with integral stub shaft 304) is part of a rotor that includes a compressor and shaft. In this configuration the tie-bolt 306 passes down the center of the rotor to hold these three pieces together. One end of the tie-bolt 306 is fixed to the compressor. The nut 308 is threaded onto the other end and used to hold the rotor assembly together by reacting against the turbine stub shaft 304.Attorney Docket No. BEEHI-1038PCT Patent Application

[0044] A channel, such as channel 202, can be formed between the stub shaft 304 and inner race 310 for the bearing 312. The bearing 312 is further mounted in a housing 314 with inner race 310 and outer race 322. The inner race 310 can be positioned against a spacer 316. The spacer 316 can comprise a washer between the tie-bolt nut 308 and the bearing 312. In some embodiments there is no spacer, and the nut 308 can just react against the stub shaft 304.

[0045] The channel 202 can comprise multiple channels formed along the length of the shaft 304 (for example, as illustrated in FIG. 2). In certain embodiments, the channels 202 can be formed with nominally vertical sidewalls perpendicular to the bottom surface of the channel, forming a three sided channel in the shaft 304. The plurality of channels 202 can be equally spaced around a diameter of the shaft 304.

[0046] Parameters of the channel(s) 202 can be adjusted according to the constraints of a particular application. For example, the width of the channels 202, the number of channels 202, and the flow area through each of the channels 202 can be varied as necessary to achieve the desired cooling. In certain embodiments, the shape of the channels 202 can also be selected to be cylindrical, tubular, or in the shape of a “V”, in accordance with design considerations and to maximize cooling for the particular application.

[0047] Fluid 318 can flow into the cooling air chamber 320. The cooling air chamber 320 can comprise a space formed by the housing 314. The fluid 318 can flow from the cooling air chamber 320 through the channel(s) 202. The cooling air 318 reduces the bearing 312 temperature convectively. The cooling air 318 (which is now hotter since it has accepted heat from the bearing 312) then flows out of the channel(s) 202 through the housing 314 and exits the system 300, for example into a buffer cavity. It should be appreciated that the fluid 318 can comprise air, or any other such fluid that can flow through the channels 202. In most cases, the fluid can be embodied as a gas.

[0048] FIG. 4 illustrates aspects of another embodiment of a system 400 for cooling a bearing and race assembly in accordance with the disclosed embodiments. In this embodiment, the system 400 can comprise a full annular channel 404 provided beneath aAttorney Docket No. BEEHI-1038PCT Patent Application portion of shaft 304, supporting the bearing 312, for the cooling air 318 to flow. Radial holes 408 are disposed between the rest of the shaft and bearing that allow fluid to exit. The bearing 312 sits on a continuous shaft section 402 of the stub shaft 304. The stub shaft 304 can be in operable relation to the tie-bolt 306 and nut 308.

[0049] The relation of the stub shaft section 402 and the tie bolt 306 is selected such that an annulus 404 is formed, which allows the cooling fluid to flow therethrough. The bearing 312 is further mounted in a housing 314 between inner race 310 and outer race 322. The inner race 310 is positioned against a nut 406.

[0050] The cooling air 318 flows beneath the section 402 of shaft 304. A series of slots, holes, or orifices 408 separate the section of shaft 402 connected to the bearing 312 from the rest of the shaft 304.

[0051] The cooling air (or fluid) 318 can flow into the cooling air chamber 320 formed by the housing 314. The air 318 can flow from the cooling air chamber 320 through the annular channel 404. The holes 408 allow the cooling air 318 to flow beneath and around the bearing 312, and can reduce conduction from the bulk of the shaft to the bearing 312. The cooling air 318 thereby reduces the bearing 312 temperature. The air 318 then flows out of the channel through the housing 314 and exits the system 400 to the rear.

[0052] FIG. 5 illustrates steps associated with a method 500 for manufacturing a shaft with fluid cooling channels as disclosed herein. The method starts at 505.

[0053] For certain applications, the relative cooling for a given race and bearing assembly can be identified at step 510. For example, some race and bearing assemblies may be mounted to another component of the system that is a heat source. In such cases the depth and width of the channels, along with the channels’ shape, and the total number of channels can be selected to provide more cooling. In other cases, the race and bearing assembly might be connected to a heat sink. In such cases less cooling may be necessary. The depth and width of the channels, along with the channels’ shape, and number of channels can be selected to provide less cooling in such applications.Attorney Docket No. BEEHI-1038PCT Patent Application

[0054] Similarly, at step 515, the structural load requirements for the shaft can be identified. The load requirements for the shaft will differ according to the application for the shaft. Applications with higher load requirements will have a different structural integrity requirement for the shaft than applications with lower load requirements. The load requirements for the shaft may dictate certain design criteria for the channels formed in the shaft.

[0055] At step 520 the design parameters for the shaft, and channels formed therein can be selected. The design parameters for the channel will depend on both the necessary cooling identified at step 510, and the structural requirements identified at step 515.

[0056] At step 525, the part can be manufactured to the specifications established at step 520, so that the resulting shaft, and channels therein, provide the necessary cooling and structural integrity. It should be appreciated that, in certain embodiments, additive manufacturing can be used to manufacture the part. In other embodiments, other manufacturing processes can be used. The method ends at step 530.

[0057] FIG. 6 illustrates steps associated with a method 600 for cooling a bearing and race assembly, in accordance with the disclosed embodiments. The method starts at step 605.

[0058] At step 610 a fluid (which can be air, or other such fluids) can be directed into a housing. Most commonly the fluid is directed into the housing by operation of a turbine. In such embodiments, the fan associated with the turbine will create airflow, so motion of the entire turbine is not required to provide the necessary fluid flow. In other embodiments, other mechanisms may be used to generate airflow at step 610. The airflow can comprise fluid at a lower temperature than the temperature of the bearing and race assembly.

[0059] At step 615, the fluid flow enters the cooling air chamber, creating a pressure differential. The pressure differential allows some of the air in the cooling air chamber to flow into the channels formed in the shaft at step 620. The air flow conductively and / or convectively transfers heat away from the proximate race and bearing assembly, as well as the stub shaft, as shown at step 625.Attorney Docket No. BEEHI-1038PCT Patent Application

[0060] The heated air is then vented out of the system at step 630. The method thus transfers heat energy away from the race and bearing assembly effectively cooling the race and bearing assembly. The method ends at step 635.

[0061] Based on the foregoing, it can be appreciated that a number of embodiments, preferred and alternative, are disclosed herein.

[0062] In an embodiment, a system and method for cooling a race and bearing assembly comprises a shaft for a turbine, and at least one channel configured in the shaft, wherein the shaft is configured to interface with a race and bearing assembly and the channels are configured to allow air to flow therethrough.

[0063] It should be appreciated that variations of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. For example, in an embodiment, a bearing cooling system comprises a shaft and at least one channel formed in the shaft, wherein the shaft is configured to interface with a race and bearing assembly. In an embodiment, the at least one channel is formed on an external surface of the shaft. In an embodiment, the channels are configured to allow fluid to flow therethrough. In an embodiment, the fluid comprises air. In an embodiment, the bearing cooling system further comprises an air chamber formed by a housing associated with the turbine. In an embodiment, the at least one channel further comprises two sidewalls formed in the shaft and a bottom surface nominally perpendicular to the two sidewalls. In an embodiment, the at least one channel further comprises two sidewalls meeting nominally at a trough, forming a “v” shape. In an embodiment, the at least one channel further comprises a tubular shape. In an embodiment, the at least one channel further comprises a plurality of channels. In an embodiment, the plurality of channels are equally spaced around a diameter of the shaft. In an embodiment, the shaft is configured for a turbomachine. In an embodiment, the turbomachine comprises a turbine.

[0064] In an embodiment, a cooling system for a turbomachine comprises a race and bearing assembly, a shaft, and a plurality of channels formed in an external surface of theAttorney Docket No. BEEHI-1038PCT Patent Application shaft, wherein the shaft is configured to interface with the race and bearing assembly. In an embodiment, the plurality of channels are configured to allow fluid to flow proximate to the race and bearing assembly. In an embodiment the cooling system for a turbomachine further comprises an air chamber formed by a housing associated with the turbine. In an embodiment, each of the plurality of channels further comprise two sidewalls formed in the shaft and a bottom surface nominally perpendicular to the two sidewalls. In an embodiment, the plurality of channels are equally spaced around a diameter of the shaft.

[0065] In an embodiment, a method for cooling a bearing and race assembly comprises configuring a shaft to interface with the bearing and race assembly, forming a plurality of channels in the shaft, and flowing a fluid through the plurality of channels in the shaft. In an embodiment, the method for cooling a bearing and race assembly further comprises creating a pressure differential in an air chamber formed by a housing associated with the turbine, the pressure differential driving the fluid to flow through the plurality of channels in the shaft. In an embodiment, the plurality of channels are equally spaced around a diameter of the shaft.

[0066] It should be understood that various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.

Claims

Attorney Docket No. BEEHI-1038PCT Patent ApplicationCLAIMSWhat is claimed is:1 . A bearing cooling system comprising: a shaft; and at least one channel formed in the shaft, wherein the shaft is configured to interface with a race and bearing assembly.

2. The bearing cooling system of claim 1 wherein the at least one channel is formed on an external surface of the shaft.

3. The bearing cooling system of claim 1 wherein the at least one channel is configured to allow fluid to flow therethrough.

4. The bearing cooling system of claim 3 wherein the fluid comprises air.

5. The bearing cooling system of claim 1 further comprising: an air chamber formed by a housing associated with a turbine.

6. The bearing cooling system of claim 1 wherein the at least one channel further comprises: two sidewalls formed in the shaft; and a bottom surface nominally perpendicular to the two sidewalls.

7. The bearing cooling system of claim 1 wherein the at least one channel further comprises: two sidewalls meeting nominally at a trough, forming a “v” shape.

8. The bearing cooling system of claim 1 wherein the at least one channel further comprises: a tubular shape.

9. The bearing cooling system of claim 1 wherein the at least one channel further comprises: a plurality of channels.Attorney Docket No. BEEHI-1038PCT Patent Application10. The bearing cooling system of claim 9 wherein the plurality of channels are equally spaced around a diameter of the shaft.1 1 . The bearing cooling system of claim 1 wherein the shaft is configured for a turbomachine.

12. The bearing cooling system of claim 11 wherein the turbomachine comprises: a turbine.

13. A cooling system for a turbomachine comprising: a race and bearing assembly; a shaft; and a plurality of channels formed in an external surface of the shaft, wherein the shaft is configured to interface with the race and bearing assembly.

14. The cooling system for a turbomachine of claim 13 wherein the plurality of channels are configured to allow fluid to flow proximate to the race and bearing assembly.

15. The cooling system for a turbomachine of claim 13 further comprising: an air chamber formed by a housing associated with a turbine.

16. The cooling system for a turbomachine of claim 13 wherein each of the plurality of channels further comprises: two sidewalls formed in the shaft; and a bottom surface nominally perpendicular to the two sidewalls.

17. The cooling system for a turbomachine of claim 13 wherein the plurality of channels are equally spaced around a diameter of the shaft.

18. A method for cooling a bearing and race assembly comprising: configuring a shaft to interface with the bearing and race assembly;Attorney Docket No. BEEHI-1038PCT Patent Application forming a plurality of channels in the shaft; and flowing a fluid through the plurality of channels in the shaft.

19. The method for cooling a bearing and race assembly of claim 18 further comprising: creating a pressure differential in an air chamber formed by a housing associated with a turbine, the pressure differential driving the fluid to flow through the plurality of channels in the shaft.

20. The method for cooling a bearing and race assembly of claim 18 wherein the plurality of channels are equally spaced around a diameter of the shaft.

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