Multipad hybrid conical foil bearing

A conical bearing includes a bearing sleeve, a bump foil, and a top foil. The bearing sleeve extends along an axis from a first open end to a second open end. The bearing sleeve has an axially tapered shape such that a first diameter of the bearing sleeve is greater than a second diameter of the bearing sleeve. An interior surface of the bearing sleeve has a non-circular profile. The bump foil is concentrically disposed within the bearing sleeve and includes bump foil pad segments extending circumferentially about the interior surface of the bearing sleeve. Each bump foil pad segment comprises a plurality of foil bumps and the plurality of foil bumps varies in stiffness along a circumference of the bump foil. The top foil is concentrically disposed within the bump foil and includes top foil pad segments extending circumferentially about an interior surface of the bump foil.

BACKGROUND

The present invention relates generally to foil bearings, and in particular to a conical foil bearing design.

Turbomachinery supported on hydrodynamic foil bearings typically requires a set of journal and thrust bearings to support radial and axial loads. Conical bearings support both radial and axial loads, which eliminates the need for thrust bearings. However, most foil journal bearings are cylindrical. Limited conical bearing designs, with cylindrical bores on either end of the sleeve, rely on uniform spring stiffness in a single or multipad configuration with limited capability to support dynamic operational loads.

SUMMARY

As discussed herein, a conical bearing includes a bearing sleeve, a bump foil, and a top foil. The bearing sleeve extends along an axis from a first open end to a second open end. The bearing sleeve has an axially tapered shape such that a first open end diameter of the bearing sleeve is greater than a second open end diameter of the bearing sleeve. An interior surface of the bearing sleeve has a non-circular profile. The bump foil is concentrically disposed within the bearing sleeve with respect to the axis and includes a plurality of bump foil pad segments extending circumferentially about the interior surface of the bearing sleeve. Each bump foil pad segment comprises a plurality of foil bumps and the plurality of foil bumps varies in stiffness along a circumference of the bump foil. The top foil is concentrically disposed within the bump foil with respect to the axis and includes a plurality of top foil pad segments extending circumferentially about an interior surface of the bump foil.

As further discussed herein, a shaft system includes a shaft and a conical bearing oriented about an end of the shaft. The conical bearing includes a bearing sleeve, a bump foil, and a top foil. The bearing sleeve extends along an axis from a first open end to a second open end. The bearing sleeve has an axially tapered shape such that a first open end diameter of the bearing sleeve is greater than a second open end diameter of the bearing sleeve. An interior surface of the bearing sleeve has a non-circular profile. The bump foil is concentrically disposed within the bearing sleeve with respect to the axis and includes a plurality of bump foil pad segments extending circumferentially about the interior surface of the bearing sleeve. Each bump foil pad segment comprises a plurality of foil bumps and the plurality of foil bumps varies in stiffness along a circumference of the bump foil. The top foil is concentrically disposed within the bump foil with respect to the axis and includes a plurality of top foil pad segments extending circumferentially about an interior surface of the bump foil.

As also discussed herein, a method of manufacturing a conical bearing includes manufacturing a bearing sleeve of the conical bearing such that the bearing sleeve extends about a central bearing sleeve cavity from a first open end to a second open end and has a tapered shape such that a first open end diameter of the bearing sleeve is greater than a second open end diameter of the bearing sleeve, and such that an interior surface of the bearing sleeve has a non-circular profile. A plurality of bump foil pad segments are manufactured, wherein each bump foil pad segment comprises a plurality of foil bumps and the plurality of foil bumps varies in stiffness along a length of the bump foil pad segment. A plurality of top foil pad segments are manufactured. The bump foil pad segments are assembled into a bump foil which extends about a central bump foil cavity from a first open end to a second open end and has a tapered shape such that a first open end diameter of the bump foil is greater than a second open end diameter of the bump foil. The top foil pad segments are assembled into a top foil which extends about a central top foil cavity from a first open end to a second open end and has a tapered shape such that a first open end diameter of the top foil is greater than a second open end diameter of the top foil. The bump foil is inserted into the central bearing sleeve cavity through the first open end of the bearing sleeve such that the bump foil is concentrically disposed within the bearing sleeve with respect to an axis about which the bearing sleeve extends. The top foil is inserted into the central bump foil cavity through the first open end of the bump foil such that the top foil is concentrically disposed within the bump foil with respect to the axis.

DETAILED DESCRIPTION

A conical bearing can incorporate foils, including a bump foil having varying bump pitch and/or bump height to better control bearing stiffness at locations which are expected to experience higher load during shaft rotation. The foils can be segmented and axially split for easier assembly. The bearing sleeve of the conical bearing can be additively manufactured to include features such as support slots or dovetails to retain the foil ends, anti-rotation tabs, cooling channels, and/or cooling holes. The cooling holes extending from the bearing sleeve's outer diameter to the inner diameter enable a hybrid bearing configuration for improved load-capacity of the bearing. The interconnecting holes further assist in heat dissipation from the bearing. The cooling channels on the outer diameter of the bearing sleeve can provide air flow passages to dissipate heat from the conical bearing via forced convection.

Each end of the conical bearing has a non-cylindrical inner diameter and can include a three-pad configuration. This allows the pads to be designed to control the geometry of each pad for offset. Additionally, the pads can be designed to be preloaded such that the center of curvature of the pad or lobe is not coincident with the geometric center of the bearing. Each lobe assists in hydrodynamic pressure generation from the leading edge to the trailing edge when the shaft is rotating counterclockwise. The sleeve inner diameter profile transitions from diverging to converging in order to assist in hydrodynamic pressure build up. The compliant bump foils on the leading edge engage with the bearing sleeve's inner diameter first. As the shaft speed increases along with the dynamic load, the bumps near the trailing edge start to become engaged with the sleeve, thus providing load support. In essence, bump foils compliance increases from leading to the trailing edge in the circumferential direction. The hydrodynamic air film thickness decreases from leading to the trailing edge. Additionally, the bump foils can be split axially along the length of the bearing to allow for improved bump foil stiffness. This axial split provides compliance to the dynamic load, minimizing foil deformation.

FIGS.1A-1Bare schematic sectional depictions of shaft system10. Shaft system10includes shaft12and bearing14.FIG.2is a schematic depiction of the load experienced by bearing14due to the rotation of shaft12within bearing14.FIGS.1A-2will be discussed in turn below.

As shown inFIG.1A, shaft12rests on bearing14when shaft12is not rotating due to gravity. As shaft12begins to rotate (shown inFIGS.1A-1B), it draws air and creates a hydrodynamic pressure wedge between the shaft12and bearing14. This hydrodynamic pressure wedge lifts shaft12off of the foil geometry of bearing14.FIG.2depicts the load W exerted by shaft12on bearing14and the hydrodynamic pressure P generated by bearing14during the rotation of shaft12. Hydrodynamic pressure P generated by bearing14varies at different points in the rotation of shaft12. Hydrodynamic pressure P is highest at particular points in the rotation of shaft12(which occur repeatedly at particular locations along bearing14). Hydrodynamic pressure typically increases along the leading edge16of the foil sections of bearing14and is greatest near the trailing edge18of each foil section (specifically, at or near point20, where the air film is also at a minimum). As described in more detail below, varying bump pitch and/or bump height, and axial split along the pad length within the foil geometry of bearing14allows for targeted dynamic stiffness control in these areas. This allows bearing liftoff to be more efficiently achieved, and bearing loading can be adjusted based on the expected loads and performance of the bearing.

FIG.3Ais a side view of conical bearing100about shaft102and disposed along axis X. Conical bearing100includes bearing sleeve104, bump foil106(shown inFIGS.4A-4B), and top foil108(shown inFIGS.4A-4B). Conical bearing100extends from inner end110to outer end112and includes exterior surface114and interior surface116(shown inFIG.5B). In the example shown inFIGS.3A-3C, bearing sleeve104includes cooling channels118.FIG.3Bis a perspective view of inner end110of conical bearing100.FIG.3Cis a perspective view of outer end112of conical bearing100.FIGS.3A-3Cwill be discussed concurrently.

Conical bearing100has a hollow, axially tapered shape such that the diameter of a first open end (such as inner end110) is greater than the diameter of an opposite second open end (such as outer end112). Outer end112and inner end110are shaped such that a section of shaft102can extend through interior cavity116(shown inFIG.5B) of conical bearing100. As described in more detail below in reference toFIGS.6A-6C, the tapered shape of conical bearing100can support both radial and axial loads exerted by shaft102during rotation. In some examples, conical bearing100has a length of between approximately 0.5 inches (approximately 12.7 millimeters) and approximately 3 inches (approximately 76.2 millimeters).

Bearing sleeve104forms an outer layer of conical bearing100with respect to the location of shaft102. Bearing sleeve104, including cooling channels118, can be additively manufactured. Bump foil106forms a middle layer of conical bearing100and is located on the interior of bearing sleeve104, being concentrically disposed within bearing sleeve104with respect to axis X when conical bearing100is assembled. Top foil108forms an inside layer of conical bearing100and is adjacent to shaft102, and is concentrically disposed within bump foil106with respect to axis X when conical bearing100is assembled. Bump foil106and top foil108can be single wrap foils, such that each of bump foil106and top foil108form a single layer about shaft102. Bump foil106and top foil108can be formed of the same material. In some examples, bump foil106and top foil108are formed of a high-strength nickel-based alloy.

Bump foil106distributes the load exerted by shaft102on conical bearing100when shaft102rotates. As described in more detail below in reference toFIGS.6A-6C, bump foil106can have a varying stiffness due to variations in bump geometry along bump foil106. Bump foil106can be formed out of a flat sheet and shaped with a die.

FIG.4Ais a partially exploded view of conical bearing100, andFIG.4Bis an exploded view of conical bearing100and shaft102. Conical bearing100includes bearing sleeve104, bump foil106, and top foil108. Conical bearing100extends from inner end110(shown inFIGS.3A-3C and5B) to outer end112(shown inFIGS.3A-3C and5A), and includes exterior surface114(shown inFIGS.3A-3C and5A) and interior surface116(shown inFIG.5B). In the example depicted inFIGS.4A-5B, bearing sleeve104includes cooling channels118. Bump foil106is axially split and includes first bump foil section120and second bump foil section122(both shown inFIG.4A). Top foil108is axially split, and includes first top foil section124and second top foil section126. First bump foil section120and second bump foil section122can each include bump foil pad segments128(shown inFIG.4B). First top foil section124and second top foil section126can each include top foil pad segments130(shown inFIG.4B). Bearing sleeve104extends about central bearing sleeve cavity132from first open end134to second open end136. Bump foil106extends about central bump foil cavity138from first open end140to second open end142. Top foil108extends about central top foil cavity144from first open end146to second open end148. Exterior surface114of conical bearing100is the exterior surface of bearing sleeve104, and bearing sleeve104also includes interior surface150. Bump foil106has an exterior surface152and an interior surface154. Interior surface116of conical bearing100is the interior surface of top foil108, and top foil108also includes exterior surface156.FIG.5Ais a top plan view of outer end112of conical bearing100.FIG.5Bis a bottom plan view of inner end110of conical bearing100.FIGS.4A-5Bwill be discussed concurrently below.

As described in more detail below in reference toFIG.7C, the thickness of bearing sleeve104can vary to accommodate the shape of bump foil106, and interior surface150of bearing sleeve104can have a non-circular profile. In the example depicted inFIG.4A, each of first bump foil section120and second bump foil section122includes three bump foil pad segments128. Similarly, each of first top foil section124and second top foil section126includes three top foil pad segments130. In some examples, bump foil pad segments128can be evenly circumferentially distributed such that each bump foil pad segment128makes up approximately one third of the circumference of bump foil106. Similarly, top foil pad segments130can be evenly circumferentially distributed such that each top foil pad segment130makes up approximately one third of the circumference of top foil108.

The stiffness of bump foil106can be varied circumferentially along the length of each bump foil pad section128(from the leading edge to the trailing edge). To increase bearing stiffness and damping, the bump foil pitch can be increased from each leading edge to each trailing edge, the bump foil height can be decreased from each leading edge to each trailing edge, or a combination of decreased pitch and increased height can be used. In these designs, the bearing assembly clearance can decrease from the leading edge to the trailing edge.

Both bump foil pad segments128and top foil pad segments130can be insertable into bearing sleeve104through central bearing sleeve cavity132. Top foil pad segments130can be insertable into bump foil pad segments128after bump foil pad segments128are assembled into bump foil106and/or inserted into bearing sleeve104. As described in more detail below in reference toFIGS.8-9, each bump foil pad segment128and/or top foil pad segment130can include geometry which slots into, and is secured by, bearing sleeve support features.

In step202, a bearing sleeve of the conical bearing is manufactured. The bearing sleeve can extend about a central bearing sleeve cavity (such as central bearing sleeve cavity132, shown inFIGS.4A-4B) and can have a tapered shape such that the diameter of a first open end of the bearing sleeve (such as first open end134of bearing sleeve104, shown inFIGS.4A-4B) is greater than the diameter of a second open end of the bearing sleeve (such as second open end136of bearing sleeve104, shown inFIGS.4A-4B). The bearing sleeve can be additively manufactured and can, in some examples, include additively manufactured cooling channels and/or cooling holes. Additively manufacturing the bearing sleeve can include forming any of: at least one support slot in an interior surface of the bearing sleeve, at least one support dovetail in an interior surface of the bearing sleeve, a plurality of cooling channels in an exterior surface of the bearing sleeve, a plurality of cooling holes extending radially outward through the bearing sleeve such that an interior end of each cooling hole is adjacent to the central bearing sleeve cavity and an exterior end of each cooling hole is within a cooling channel, and/or any combination of forming these features. Additionally or alternatively, the cooling holes and/or cooling channels can be formed by subtractive manufacturing processes such as milling.

In step204, a plurality of bump foil pad segments (such as bump foil pad segments128, shown inFIG.4B) are manufactured. Each bump foil pad segment can include a plurality of foil bumps which varies in stiffness along a length of the bump foil pad segment. The bump foil pad segments can be formed out of a sheet of a sheet metal and can be shaped with a die to form the plurality of foil bumps.

In step206, a plurality of top foil pad segments (such as top foil pad segments130, shown inFIG.4B) are manufactured. The top foil pad segments can be formed out of a sheet metal.

In step208, the bump foil pad segments are assembled into a bump foil (such as bump foil106, shown inFIG.4A). The bump foil can extend about a central bump foil cavity (such as central bump foil cavity138, shown inFIG.4A) from a first open end (such as first open end140of bump foil106, shown inFIG.4A) to a second open end (such as second open end142of bump foil106, shown inFIG.4A) and can have a tapered shape such that the diameter of the first open end of the bump foil is greater than the diameter of the second open end of the bump foil.

In step210, the top foil pad segments are assembled into a top foil (such as top foil108, shown inFIG.4A). The top foil can extend about a central top foil cavity (such as central top foil cavity144, shown inFIG.4A) from a first open end (such as first open end146of top foil108, shown inFIG.4A) to a second open end (such as second open end148of top foil108, shown inFIG.4A) and can have a tapered shape such that the diameter of the first open end of the top foil is greater than the diameter of the second open end of the top foil.

In step212, the bump foil is inserted into the central bearing sleeve cavity through the first open end of the bearing sleeve. In some examples, one or more protruding sections of the bump foil can slide into a corresponding section on the interior surface of the bearing sleeve (such as support dovetails and/or support slots).

In step214, the top foil is inserted into the central bump foil cavity through the first open end of the bump foil. In some examples, one or more protruding sections of the top foil can slide into a corresponding section on the interior surface of the bearing sleeve (such as support dovetails and/or support slots).

FIG.7Ais a perspective view of an inner end of conical bearing300about shaft302. Conical bearing300includes bearing sleeve304, bump foil306, and top foil308(shown inFIGS.7B-7C). Conical bearing300extends from inner end310to outer end312and includes exterior surface314and interior surface316(shown inFIGS.7B-7C). In the example shown inFIGS.7A-7C, bearing sleeve304includes cooling channels318. Bump foil306includes foil bumps320(shown inFIG.7C).FIG.7Bis a cross-sectional view of conical bearing300along plane A (shown inFIG.7A).FIG.7Cis a cross-sectional view of a portion of conical bearing300along plane B (shown inFIG.7B).FIGS.7A-7Cwill be discussed concurrently below.

Conical bearing300can operate in substantially the same manner as conical bearing100(described above in reference toFIGS.3A-5B and7A-7C) with respect to the support of shaft302during rotation.

As shown inFIGS.7A and7C, bump foil306can have a varying geometry along its circumference in order to vary the stiffness of bump foil306. This can be achieved by, for example, varying the bump height and/or bump pitch of bump foil306along its circumference (as described above in reference toFIGS.4A-4B). As described above in reference toFIG.2, the loads exerted by shaft302vary based on the rotational position of shaft302. The stiffness of bump foil306can be varied to distribute the expected loads exerted by shaft302at different rotational positions. As shown inFIG.7C, the radius of bearing sleeve304can also be varied along the circumference of bearing sleeve304to accommodate the differing dimensions of bump foil306and the expected movement of shaft302during rotation. For example, radius R1of bearing sleeve304(aligning with an area of lesser bump height and greater bump pitch within bump foil306) is less than radius R2(aligning with an area of greater bump height and lesser bump pitch within bump foil306, as well as with the location of maximum pre-load on the bearing). The varying radius of bearing sleeve304can result in a non-circular profile of the interior surface of bearing sleeve304. This varying radius of bearing sleeve304is shown inFIG.7C(also shown inFIGS.2and5B), and can assist in generation of hydrodynamic pressure from the leading edge of each bump foil pad section to the trailing edge.

As shown inFIG.7B, shaft302exerts force on conical bearing300as shaft302rotates. Shaft302exerts radial force on conical bearing300along direction Fradialand exerts axial force on conical bearing300along direction Faxial. As the loads exerted by shaft302vary based on the rotational position of shaft302, conical bearing300can distribute the varying loads exerted by shaft302through the variable stiffness of bump foil306.

As shown inFIG.7C, bump foil306can include a plurality of foil bumps320. Each foil bump320has a bump height H and a bump pitch p. Foil bumps320can vary in height and/or pitch along the circumference of bump foil306in order to vary the stiffness of bump foil306. As described above in reference toFIG.2, the loads exerted by shaft302vary based on the rotational position of shaft302. The stiffness of bump foil306can be tailored at different points to achieve the necessary load distribution.

FIG.8is a cross-sectional view of a portion of conical bearing400and a portion of shaft402. Conical bearing400includes bearing sleeve404, bump foil406, and top foil408. Conical bearing400extends from an inner end (not shown inFIG.8) to an outer end (not shown inFIG.8). Bearing sleeve404includes cooling channel410and support slot412. Bump foil406includes bump foil leading edge414, bump foil trailing edge416, and foil bumps418. Top foil408includes top foil leading edge420and top foil trailing edge422.

Conical bearing400can operate in substantially the same manner as conical bearing100(described above in reference toFIGS.3A-5B and7A-7C) with respect to the support of shaft402during rotation.

Bump foil leading edge414and top foil leading edge420can extend radially outward from the center of bump foil406and top foil408, respectively. Support slot412can be shaped to match the geometry (for example, the length and angle) of bump foil leading edge414and top foil leading edge420. In the example shown inFIG.8, support slot412is a slot which extends radially outward from the center of bearing sleeve404and which extends axially along bearing sleeve404in the same manner as cooling channel410. When conical bearing400is assembled, bump foil leading edge414and top foil leading edge420can be slidably inserted into support slot412to secure the respective bump foil or top foil pad segment within bearing sleeve404. Additionally, support slot412can secure bump foil leading edge414and top foil leading edge420during rotation of shaft402by pinning the foils in place at their respective leading edges. In designs including one or more support slots412, bump foil trailing edge416and top foil trailing edge422are left free. In examples where each of bump foil406and top foil408include three pad sections extending circumferentially about the foil, bearing sleeve404can include three support slots412.

FIG.9is a cross-sectional view of a portion of conical bearing500and a portion of shaft502. Conical bearing500includes bearing sleeve504, bump foil506, and top foil508. Conical bearing500extends from an inner end (not shown inFIG.9) to an outer end (not shown inFIG.9). Bearing sleeve504includes cooling channel510and support dovetail512. Bump foil506includes bump foil leading edge514, bump foil trailing edge516, and foil bumps518. Top foil508includes top foil leading edge520and top foil trailing edge522. Support dovetail512can include leading edge side524and trailing edge side526.

Conical bearing500can operate in substantially the same manner as conical bearing100(described above in reference toFIGS.3A-5B and7A-7C) with respect to the support of shaft502during rotation.

Top foil leading edge520and top foil trailing edge522can each have a stepped shape. In this manner, a portion of both top foil leading edge520and top foil trailing edge522can extend radially outward from the center of top foil508. A radially outermost portion of both top foil leading edge520and top foil trailing edge522can extend circumferentially from the radially extending portions, in the same manner as the rest of top foil508. Support dovetail512can extend radially inward toward the center of bearing sleeve504and can be shaped to match the geometry (for example, the length, shape, and angle) of top foil leading edge520and top foil trailing edge522. In the example shown inFIG.9, support dovetail512includes two recessed areas (leading edge side524and trailing edge side526) to receive the corresponding geometry of bump foil506and top foil508. When conical bearing500is assembled, top foil leading edge520can be slidably inserted into leading edge side524of support dovetail512to secure the leading edge of the respective top foil pad segment within bearing sleeve504. Similarly, top foil trailing edge522can be slidably inserted into trailing edge side526of support dovetail516to secure the trailing edge of the respective top foil pad segment within bearing sleeve504. Additionally, support dovetail512can secure bump foil leading edge514and top foil leading edge520during rotation of shaft502by retaining the foils in place at their respective leading edges. Similarly, support dovetail512can secure bump foil trailing edge516and top foil trailing edge522during rotation of shaft502by retaining the foils in place at their respective trailing edges. In this manner, in designs including one or more support dovetails512, bump foil leading edge514, bump foil trailing edge516, top foil leading edge520, and top foil trailing edge522are secured by the geometry of support dovetail(s)512. In examples where each of bump foil506and top foil508include three pad sections extending circumferentially about the foil, bearing sleeve504can include three support dovetails512which align with the end of each pad section.

FIG.10Ais a perspective view of conical bearing600oriented about shaft602. Conical bearing600includes bearing sleeve604, bump foil606, and top foil608. Conical bearing600extends from inner end610to outer end612. In the example shown inFIGS.10A-10B, bearing sleeve604includes cooling channels614and anti-rotation tabs616.FIG.10Bis a side view of conical bearing600at inner end612.FIGS.10A-10Bwill be discussed concurrently.

Conical bearing600can be made in substantially the same way, and operate in substantially the same manner with respect to the support of shaft602during rotation, as conical bearing100(described above in reference toFIGS.3A-7C).

Bearing sleeve604can include one or more anti-rotation tabs616. Anti-rotation tabs616can be built with bearing sleeve604during the additive manufacturing build process, such that bearing sleeve604is a monolithic structure. Alternatively, anti-rotation tabs616can be built separately, and bearing sleeve604can be assembled after construction. Anti-rotation tabs616help to prevent rotation of bearing sleeve604during operation (that is, during rotation of shaft602). In some examples, anti-rotation tabs616can be fitted against corresponding holes within the support housings (not shown) for conical bearing600. This can help limit the rotation of bearing sleeve604within the support housing if shaft602were to catch against bearing sleeve604.

FIG.11Ais a perspective view of conical bearing700oriented about shaft702. Conical bearing700includes bearing sleeve704, bump foil706, and top foil708(shown inFIG.11C). Conical bearing700extends from inner end710to outer end712. In the example shown inFIGS.11A-11C, conical bearing includes cooling channels714and cooling holes716.FIG.11Bis a top plan view of a portion of bearing sleeve704including cooling channel714and cooling holes716.FIG.11Cis an interior perspective view of conical bearing700, including bearing sleeve704, bump foil706, top foil708, cooling holes716, foil bumps718, and support dovetail720.FIGS.11A-11Cwill be discussed concurrently.

Conical bearing700can operate in substantially the same manner as conical bearing100(described above in reference toFIGS.3A-5B and7A-7C) with respect to the support of shaft702during rotation.

Cooling channels714can extend axially along the exterior surface of bearing sleeve704. In examples of conical bearing700which include foil geometry support features (such as support dovetail720shown inFIG.11C), a cooling channel714can be located radially outward from the support feature. Each cooling hole716can extend from an exterior end722(shown inFIG.11B) to an interior end724(shown inFIG.11C). Exterior ends722of cooling holes716can be situated within a cooling channel714, and cooling holes716can extend radially inward through bearing sleeve704toward bump foil706and top foil708. In examples of conical bearing700which include foil geometry support features (such as support dovetail720), cooling holes716can extend through the support feature such that interior ends724are adjacent to an interior cavity of conical bearing700.

Cooling channels714and cooling holes716can facilitate cooling flow about shaft702. High pressure air, or another fluid, can be directed along the exterior of bearing sleeve704along cooling channels714, and additionally or alternatively can be injected into conical bearing700to enable hybridization of the bearing by combining hydrodynamic and hydrostatic bearing for improved load capacity. Conical bearing700can utilize both hydrodynamic and hydrostatic air to more efficiently cool both conical bearing700and shaft702, and provide increased air film stiffness to support high dynamic loads. Cooling channels714can provide air flow passages to dissipate heat from conical bearing700via forced convection. Cooling holes716can supply additional cooling flow to conical bearing700via radial injection using a process fluid. Additionally or alternatively, a high pressure process fluid can be drawn into cooling holes716from an external source, such as compressor bleed air. This provides hydrostatic air to increase air film stiffness and improve bearing load capacity. Cooling holes716thus act as a control orifice to regulate bearing supply pressure hydrostatically.

It should be understood that any of the features described above in reference toFIGS.3A-11Ccan be combined into a single conical bearing. For example, a single conical bearing can incorporate any combination of axial splits in the bump foil and/or top foil, pad segments forming the bump foil and/or top foil, varying bump height, varying bump pitch, one or more support slots, one or more support dovetails, one or more anti-rotation tabs, cooling channels, and cooling holes.

A conical bearing as described herein provides numerous advantages. Integrating the axial and radial support elements removes the need for shimming and allows for the elimination of thrust bearings in the bearing system. This reduces the mass and complexity of rotor assemblies, and further can reduce the possible points of failure within the bearing system. Additionally, varying bump foil stiffness achieved through the variation of bump height and/or bump pitch accounts for changes in the direction of the loads exerted by the shaft. The conical bearing designs described herein are scalable and can be suitable for aerospace or non-aerospace applications. Axially split foil components can reduce global deformation of the bearing assembly by allowing each of the split components to locally deform independently of each other. The bearing sleeve of the conical bearing can be additively manufactured to include features such as support slots or dovetails to retain the foil ends, anti-rotation tabs, cooling channels, and/or cooling holes, which can further improve the reliability and performance of the conical bearing. Finally, the cooling components can enable hybrid (both hydrodynamic and hydrostatic) cooling of the bearing (that is, axially along the bearing, as well as through the cooling holes within the cooling channels).

DISCUSSION OF POSSIBLE EMBODIMENTS

A conical bearing includes a bearing sleeve, a bump foil, and a top foil. The bearing sleeve extends along an axis from a first open end to a second open end. The bearing sleeve has an axially tapered shape such that a first open end diameter of the bearing sleeve is greater than a second open end diameter of the bearing sleeve. An interior surface of the bearing sleeve has a non-circular profile. The bump foil is concentrically disposed within the bearing sleeve with respect to the axis and includes a plurality of bump foil pad segments extending circumferentially about the interior surface of the bearing sleeve. Each bump foil pad segment comprises a plurality of foil bumps and the plurality of foil bumps varies in stiffness along a circumference of the bump foil. The top foil is concentrically disposed within the bump foil with respect to the axis and includes a plurality of top foil pad segments extending circumferentially about an interior surface of the bump foil.

The conical bearing of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:

A conical bearing according to an exemplary embodiment of the present invention, among other possible things, includes a bearing sleeve, a bump foil, and a top foil. The bearing sleeve extends along an axis from a first open end to a second open end. The bearing sleeve has an axially tapered shape such that a first open end diameter of the bearing sleeve is greater than a second open end diameter of the bearing sleeve. An interior surface of the bearing sleeve has a non-circular profile. The bump foil is concentrically disposed within the bearing sleeve with respect to the axis and includes a plurality of bump foil pad segments extending circumferentially about the interior surface of the bearing sleeve. Each bump foil pad segment comprises a plurality of foil bumps and the plurality of foil bumps varies in stiffness along a circumference of the bump foil. The top foil is concentrically disposed within the bump foil with respect to the axis and includes a plurality of top foil pad segments extending circumferentially about an interior surface of the bump foil.

A further embodiment of the foregoing conical bearing, wherein the plurality of foil bumps varies in height along the circumference of the bump foil.

A further embodiment of any of the foregoing conical bearings, wherein the plurality of foil bumps varies in pitch along the circumference of the bump foil.

A further embodiment of any of the foregoing conical bearings, wherein the plurality of foil bumps varies in height and pitch along the circumference of the bump foil.

A further embodiment of any of the foregoing conical bearings, wherein the bump foil is axially split such that the bump foil comprises a first bump foil section and a second bump foil section.

A further embodiment of any of the foregoing conical bearings, wherein each of the first bump foil section and the second bump foil section comprise three bump foil pad segments.

A further embodiment of any of the foregoing conical bearings, wherein each bump foil pad segment extends circumferentially about one third of the circumference of the bump foil.

A further embodiment of any of the foregoing conical bearings, wherein the top foil is axially split such that the top foil comprises a first top foil section and a second top foil section.

A further embodiment of any of the foregoing conical bearings, wherein each of the first top foil section and the second top foil section comprises three top foil pad segments.

A further embodiment of any of the foregoing conical bearings, wherein the bearing sleeve comprises a plurality of cooling channels extending axially along an exterior surface of the bearing sleeve.

A further embodiment of any of the foregoing conical bearings, further comprising a plurality of cooling holes extending radially outward through the bearing sleeve such that an interior end of each cooling hole is adjacent to an interior cavity of the conical bearing and an exterior end of each cooling hole is within a cooling channel.

A shaft system includes a shaft and a conical bearing oriented about an end of the shaft. The conical bearing includes a bearing sleeve, a bump foil, and a top foil. The bearing sleeve extends along an axis from a first open end to a second open end. The bearing sleeve has an axially tapered shape such that a first open end diameter of the bearing sleeve is greater than a second open end diameter of the bearing sleeve. An interior surface of the bearing sleeve has a non-circular profile. The bump foil is concentrically disposed within the bearing sleeve with respect to the axis and includes a plurality of bump foil pad segments extending circumferentially about the interior surface of the bearing sleeve. Each bump foil pad segment comprises a plurality of foil bumps and the plurality of foil bumps varies in stiffness along a circumference of the bump foil. The top foil is concentrically disposed within the bump foil with respect to the axis and includes a plurality of top foil pad segments extending circumferentially about an interior surface of the bump foil.

A shaft system according to an exemplary embodiment of the present invention, among other possible things, includes a shaft and a conical bearing oriented about an end of the shaft. The conical bearing includes a bearing sleeve, a bump foil, and a top foil. The bearing sleeve extends along an axis from a first open end to a second open end. The bearing sleeve has an axially tapered shape such that a first open end diameter of the bearing sleeve is greater than a second open end diameter of the bearing sleeve. An interior surface of the bearing sleeve has a non-circular profile. The bump foil is concentrically disposed within the bearing sleeve with respect to the axis and includes a plurality of bump foil pad segments extending circumferentially about the interior surface of the bearing sleeve. Each bump foil pad segment comprises a plurality of foil bumps and the plurality of foil bumps varies in stiffness along a circumference of the bump foil. The top foil is concentrically disposed within the bump foil with respect to the axis and includes a plurality of top foil pad segments extending circumferentially about an interior surface of the bump foil.

A further embodiment of the foregoing shaft system, wherein the plurality of foil bumps varies in height and pitch along the circumference of the bump foil according to an expected load exerted on the conical bearing by the shaft during rotation of the shaft.

A method of manufacturing a conical bearing includes manufacturing a bearing sleeve of the conical bearing such that the bearing sleeve extends about a central bearing sleeve cavity from a first open end to a second open end and has a tapered shape such that a first open end diameter of the bearing sleeve is greater than a second open end diameter of the bearing sleeve, and such that an interior surface of the bearing sleeve has a non-circular profile. A plurality of bump foil pad segments are manufactured, wherein each bump foil pad segment comprises a plurality of foil bumps and the plurality of foil bumps varies in stiffness along a length of the bump foil pad segment. A plurality of top foil pad segments are manufactured. The bump foil pad segments are assembled into a bump foil which extends about a central bump foil cavity from a first open end to a second open end and has a tapered shape such that a first open end diameter of the bump foil is greater than a second open end diameter of the bump foil. The top foil pad segments are assembled into a top foil which extends about a central top foil cavity from a first open end to a second open end and has a tapered shape such that a first open end diameter of the top foil is greater than a second open end diameter of the top foil. The bump foil is inserted into the central bearing sleeve cavity through the first open end of the bearing sleeve such that the bump foil is concentrically disposed within the bearing sleeve with respect to an axis about which the bearing sleeve extends. The top foil is inserted into the central bump foil cavity through the first open end of the bump foil such that the top foil is concentrically disposed within the bump foil with respect to the axis.

A method of manufacturing a conical bearing according to an exemplary embodiment of the present invention, among other possible things, includes manufacturing a bearing sleeve of the conical bearing such that the bearing sleeve extends about a central bearing sleeve cavity from a first open end to a second open end and has a tapered shape such that a first open end diameter of the bearing sleeve is greater than a second open end diameter of the bearing sleeve, and such that an interior surface of the bearing sleeve has a non-circular profile. A plurality of bump foil pad segments are manufactured, wherein each bump foil pad segment comprises a plurality of foil bumps and the plurality of foil bumps varies in stiffness along a length of the bump foil pad segment. A plurality of top foil pad segments are manufactured. The bump foil pad segments are assembled into a bump foil which extends about a central bump foil cavity from a first open end to a second open end and has a tapered shape such that a first open end diameter of the bump foil is greater than a second open end diameter of the bump foil. The top foil pad segments are assembled into a top foil which extends about a central top foil cavity from a first open end to a second open end and has a tapered shape such that a first open end diameter of the top foil is greater than a second open end diameter of the top foil. The bump foil is inserted into the central bearing sleeve cavity through the first open end of the bearing sleeve such that the bump foil is concentrically disposed within the bearing sleeve with respect to an axis about which the bearing sleeve extends. The top foil is inserted into the central bump foil cavity through the first open end of the bump foil such that the top foil is concentrically disposed within the bump foil with respect to the axis.

A further embodiment of the foregoing method, wherein manufacturing the bearing sleeve comprises additively manufacturing the bearing sleeve.

A further embodiment of any of the foregoing methods, wherein additively manufacturing the bearing sleeve comprises forming at least one support slot in the interior surface of the bearing sleeve. Inserting the bump foil into the central bearing sleeve cavity comprises inserting a portion of at least one bump foil pad segment into the at least one support slot. Inserting the top foil into the central bump foil cavity comprises inserting a portion of at least one top foil pad segment into the at least one support slot.

A further embodiment of any of the foregoing methods, wherein additively manufacturing the bearing sleeve comprises forming at least one support dovetail in the interior surface of the bearing sleeve. Inserting the bump foil into the central bearing sleeve cavity comprises inserting a portion of at least one bump foil pad segment into the at least one support dovetail. Inserting the top foil into the central bump foil cavity comprises inserting a portion of at least one top foil pad segment into the at least one support dovetail.

A further embodiment of any of the foregoing methods, wherein additively manufacturing the bearing sleeve comprises forming a plurality of cooling channels in an exterior surface of the bearing sleeve.

A further embodiment of any of the foregoing methods, wherein additively manufacturing the bearing sleeve comprises forming a plurality of cooling holes extending radially outward through the bearing sleeve such that an interior end of each cooling hole is adjacent to the central bearing sleeve cavity and an exterior end of each cooling hole is within a cooling channel.

A further embodiment of any of the foregoing methods, wherein manufacturing the plurality of bump foil pad segments comprises shaping a sheet metal with a die to form the plurality of foil bumps, and wherein the plurality of foil bumps varies in height and pitch along the length of each bump foil pad segment according to an expected load exerted on the conical bearing by the shaft during rotation of the shaft.