Tilting fluid film bearings

Abstract

Various aspects relate to tilting fluid film bearings, such as bearings comprised of multiple tilting segments (302), and to rotating machinery such as turbines that include such bearings. In some examples, a slide bearing pad (304) of a tilting segment has a bearing side (310) and a pivot side (312) opposite the bearing side. The pivot side defines a socket (316) therein behind a central portion of the bearing side. A pad support (306) of the tilting segment has a ball surface (320) that extends into the socket. According to some embodiments, the ball surface or an inner surface (318) of the socket defines a radius of curvature that varies across a ball-socket interface (322). Some aspects include a method of feeding lubrication fluid to a tilting fluid film bearing segment.

Description

[0001] Atty Docket No.: 49379-0274WO1

[0002] TILTING FLUID FILM BEARINGS CROSS-REFERENCE TO RELATED APPLICATION This application claims the benefit of U.S. Provisional Application No.

[0003] 63 / 769,641 filed March 10, 2025, the disclosure of which is incorporated herein by reference in its entirety7.

[0004] TECHNICAL FIELD

[0005] This invention relates to fluid film bearings, and more particularly to such bearings comprised of multiple tilting segments, and to rotating machinery such as turbines that include such bearings.

[0006] BACKGROUND

[0007] Fluid film bearings avoid wear by maintaining a fluid film between sliding surfaces. A good example is a typical combustion engine crankshaft bearing, often formed of a soft metal like babbitt or a polymer. Hydrodynamic pressure is built between two converging surfaces. In some larger rotating machines, fluid film bearings are formed of multiple segments, each free to tilt a small amount to form a converging surface against a rotating shaft. Some such bearings are configured to cany7very high loads, which must be transmitted through the tilting bearing pad to the underlying structure. Certain types of turbines, such as wind turbines or tidal turbines, have very heavy rotating groups supported by shafts that need to be supported by bearings with as little drag as possible. Bearings in such turbines must be very reliable, as repairing or replacing such bearings can be very expensive and difficult. Furthermore, such turbines may operate at low shaft speeds and frequently stop. Improvements in fluid film bearing technology7are sought in order to improve the reliability7of such bearing systems for use in turbines, turbomachinery7and the like.

[0008] SUMMARY

[0009] One aspect of the invention features a tiltable plain bearing segment assembly that includes a slide bearing pad with two opposite broad sides including a bearing side and a pivot side, the bearing side having a bearing surface configured to form a bearing gap in cooperation with a load surface applying a load against the bearing side at a differentialAtty Docket No.: 49379-0274WO1

[0010] speed through a film of liquid, the pivot side defining a socket therein behind a central portion of the bearing side: and a pad support having a ball surface extending into the socket and bearing against an inner surface of the socket to form a ball-socket interface, such that the load applied against the bearing side is transmitted through the ball-socket interface while allowing some tilting of the slide bearing pad with respect to the pad support under load, about a pivot center defined by the ball-socket interface; wherein either the ball surface or the inner surface of the socket defines a radius of curvature that varies across the ball-socket interface.

[0011] In some examples, the ball-socket interface is configured such that the pivot center moves as the slide bearing pad tilts with respect to the pad support.

[0012] In some embodiments, the pad support comprises a domed disc.

[0013] In some cases, the domed disc includes a disc portion and a dome portion, and the ball surface is an upper surface of the dome portion.

[0014] In some embodiments, the tiltable plain bearing segment assembly further includes a seat holding the pad support, wherein the seat is fixedly coupled with the disc portion.

[0015] In some instances, the socket surface includes a central socket region defining a central socket radius of curvature, surrounded by an outer socket region defining an outer socket radius of curvature different than the central socket radius of curvature.

[0016] In some cases, the outer socket radius of curvature is larger than the central socket radius of curvature.

[0017] In some examples, the central socket region and the outer socket region blend together in a smooth transition.

[0018] In some instances, the socket surface further includes an intermediate socket region extending between the central socket region and the outer socket region, and the intermediate socket region defines an intermediate socket radius of curvature that is different than the central socket radius of curvature and the outer socket radius of curvature.

[0019] In some cases, the intermediate socket radius of curvature is larger than the central socket radius of curvature, and the outer socket radius of curvature is larger than the intermediate socket radius of curvature.

[0020] In some examples, the central socket region, the intermediate socket region, and the outer socket region blend together in smooth transitions.Atty Docket No.: 49379-0274WO1

[0021] In some instances, the ball surface includes a central ball region defining a central ball radius of curvature, surrounded by an outer ball region defining an outer ball radius of curvature different than the central ball radius of curvature.

[0022] In some cases, the outer ball radius of curvature is smaller than the central ball radius of curvature.

[0023] In some examples, the central ball region and the outer ball region blend together in a smooth transition.

[0024] In some embodiments, the ball surface further includes an intermediate ball region extending between the central ball region and the outer ball region, and the intermediate ball region defines an intermediate ball radius of curvature that is different than the central ball radius of curvature and the outer ball radius of curvature.

[0025] In some cases, the intermediate ball radius of curvature is smaller than the central ball radius of curvature, and the outer ball radius of curvature is smaller than the intermediate ball radius of curvature.

[0026] In some instances, the central ball region, the intermediate ball region, and the outer ball region blend together in smooth transitions.

[0027] In some embodiments, at least one of the ball surface or the socket surface includes an anti-wear coating overlaying a substrate.

[0028] In some examples, the pad support comprises a support seat extending laterally beyond the ball surface.

[0029] In some embodiments, the slide bearing pad is compliantly connected to the pad support on opposite sides of the ball surface, such that the slide bearing pad and, pad support form a unitary bearing cartridge.

[0030] In some cases, the tiltable plain bearing segment assembly further includes a fluid coupling connecting the slide bearing pad and the pad support and configured to supply a flow of lubricating fluid to the bearing side of the slide bearing pad.

[0031] In some instances, the fluid coupling includes a hollow rigid connector extending into respective bores in each of the slide bearing pad and the pad support and configured to angulate during tilting of the slide bearing pad with respect to the pad support.

[0032] In some examples, the slide bearing pad is a thrust bearing pad and the bearing surface is flat.

[0033] In some embodiments, the slide bearing pad is a radial bearing pad and the bearing surface is concave.

[0034] In some instances, the socket surface is void of apertures.Atty Docket No.: 49379-0274WO1

[0035] In some examples, the ball-socket interface is configured such that the pivot center moves as the slide bearing pad tilts with respect to the pad support.

[0036] Another aspect of the invention features a tiltable plain bearing segment assembly that includes a slide bearing pad with two opposite broad sides including a bearing side and a pivot side, the bearing side having a bearing surface configured to form a bearing gap in cooperation with a load surface applying a load against the bearing side at a differential speed through a film of liquid; and a pad support positioned against the pivot side of the slide bearing pad, such that the load applied against the bearing side is transmitted to the pad support while allowing some tilting of the slide bearing pad about a pivot center defined by a ball-socket interface; wherein the slide bearing pad defines a groove formed about an entire perimeter of the slide bearing pad between the bearing side and the pivot side.

[0037] In some examples, the pivot side defines a socket therein behind a central portion of the bearing side, and the pad support has a ball surface extending into the socket and bearing against an inner surface of the socket to form the ball-socket interface.

[0038] In some embodiments, the groove is located between the bearing side and a point on the ball-socket interface that is nearest the bearing side.

[0039] In some cases, the groove extends inward to a circular neck defined by the slide bearing pad.

[0040] In some instances, the groove is defined between tapered surfaces and narrows in width from an outer opening of the groove.

[0041] In some embodiments, the groove has a depth, measured across a width of the slide bearing pad, that is at least 4 percent of a lateral extent of the width of the slide bearing pad.

[0042] Another aspect of the invention features a tiltable plain bearing segment assembly that includes a slide bearing pad with two opposite broad sides including a bearing side and a pivot side, the bearing side having a bearing surface configured to form a bearing gap in cooperation with a load surface applying a load against the bearing side at a differential speed through a film of liquid; and a pad support bearing against the pivot side of the slide bearing pad, such that the load applied against the bearing side is transmitted through a ball-socket interface between the pad support and slide bearing pad while allowing some tilting of the slide bearing pad with respect to the pad support under load, about a pivot center defined by the ball-socket interface; wherein the slide bearingAtty Docket No.: 49379-0274WO1

[0043] pad is compliantly connected to the pad support on opposite sides of the ball-socket interface, such that the slide bearing pad and pad support form a unitary’ bearing cartridge.

[0044] In some embodiments, the pivot side of the slide bearing pad defines a socket of the ball-socket interface behind a central portion of the bearing side.

[0045] In some cases, the pad support has a ball surface extending into the socket and bearing against an inner surface of the socket to form the ball-socket interface.

[0046] In some examples, the tiltable plain bearing segment assembly further includes a fluid coupling connecting the slide bearing pad and the pad support and configured to supply a flow of lubricating fluid to the bearing side of the slide bearing pad.

[0047] In some instances, the fluid coupling includes a hollow rigid connector extending into respective bores in each of the slide bearing pad and the pad support and configured to angulate during tilting of the slide bearing pad with respect to the pad support.

[0048] Another aspect of the invention features a bearing support system that includes a load surface; and multiple tiltable plain bearing segment assemblies according to any of the above embodiments, arranged to each bear against the load surface to support an applied load at a speed differential between the load surface and the bearing surfaces of the tiltable plain bearing segments.

[0049] In some examples, the load surface is a cylindrical surface of a rotor, and the bearing surfaces are curved.

[0050] In some cases, the bearing surfaces are concave.

[0051] In some instances, the bearing surfaces are convex.

[0052] In some examples, the bearing surfaces are spherical.

[0053] In some embodiments, the load surface is a flat surface of an axial load collar of a rotor, and the bearing surfaces are flat.

[0054] In some cases, the multiple tiltable plain bearing segment assemblies comprise at least six tiltable plain bearing segment assemblies.

[0055] Another aspect of the invention features a method of feeding a lubrication fluid to a fluid film bearing configured to tilt about a tilt axis that includes providing a bearing pad having a bearing surface extending across a broad side of the beanng pad, the bearing pad defining an aperture at the bearing surface and defining a lubrication channel extending from the aperture to a lubrication inlet on a face of the pad; and feeding lubrication fluid to the aperture to form a fluid film at the bearing surface, by feeding the lubrication fluid into the inlet; wherein the inlet extends into the pad in a direction parallel to the tilt axis.Atty Docket No.: 49379-0274WO1

[0056] In some examples, the aperture includes a lubrication slot adjacent a leading edge of the bearing surface and wherein the lubrication channel extends from the slot to the lubrication inlet.

[0057] In some embodiments, the lubrication fluid is fed by a fluid feed coupler extending into the inlet and configured to both rotate and angulate with respect to the bearing pad during tilting of the bearing pad.

[0058] In some cases, the fluid feed coupler is sealed to have a bore of the inlet by a compliant seal at a coupler surface curved about multiple axes.

[0059] In some instances, the compliant seal comprises an O-ring set into a groove defined in the curved coupler surface.

[0060] In some embodiments, the fluid feed coupler has an inlet end extending away from the bearing pad and disposed in a cartridge removably attached to a fixed end plate disposed adjacent the bearing pad, and the method includes inserting the fluid feed coupler into the bearing pad and attaching the cartridge to the end plate to retain the fluid feed coupler in the inlet.

[0061] Some embodiments include inserting the fluid feed coupler into the bearing pad comprises inserting the fluid feed coupler into the cartridge and then inserting the cartridge into the end plate.

[0062] In some cases, attaching the cartridge to the end plate includes threading the cartridge into a threaded hole of the end plate.

[0063] In some instances, the fluid feed coupler is elongate and has opposite, spherical ends.

[0064] In some examples, the bearing surface is arcuate and the bearing pad includes a radial bearing pad.

[0065] In some cases, the bearing surface is flat and the bearing pad comprises a thrust bearing pad.

[0066] Another aspect of the invention features a fluid inlet adapter that includes a cartridge housing with an external thread and defining an interior channel extending from an inlet end of the cartridge hosing to a smooth bore extending inward from an outlet end of the cartridge housing; and an elongated, hollow and rigid fluid coupling having a first end slidingly disposed within the smooth bore and a second end extending away from the cartridge housing, wherein each end of the coupling has a partially spherical outer surface into which an o-ring groove is defined, the coupling configured to angulate, rotate andAtty Docket No.: 49379-0274WO1

[0067] translate within the smooth bore with an o-ring held within the groove of the first end sealing against the smooth bore.

[0068] In some embodiments, the fluid inlet adapter further includes a removable clip defined within a groove defined adjacent a distal end of the smooth bore and arranged to prevent removal of the coupling from the cartridge housing.

[0069] In some examples, the interior channel of the cartridge housing is configured, at the inlet end of the cartridge housing, to accommodate a pipe fitting to couple the fluid inlet adapter to a source of pressurized fluid.

[0070] Various implementations of the invention can provide a particularly robust fluid film bearing arrangement capable of withstanding very high radial loads and operating at low speeds and with frequent stops. The design of this arrangement provides simplified routing of hydraulic oil for bearing function, and can enable efficient replacement of individual bearing segments without excessive disassembly. These attributes may be particularly useful in wind and tidal turbines and in propeller shaft support, but may also be useful in other types of machinery.

[0071] The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

[0072] DESCRIPTION OF DRAWINGS FIG. 1 is a schematic side view of a wind turbine system.

[0073] FIG. 2 is a schematic representation of the rotating portion of the wind turbine system.

[0074] FIGS. 3A-3E are various views of a radial bearing and a bearing segment of the radial bearing. FIG. 3A is a perspective view of the radial bearing. FIG. 3B is a side cross-sectional view of the bearing segment. FIG. 3C is a top perspective view of the bearing segment. FIG. 3D is another side cross-sectional view of the bearing segment. FIG. 3E is a bottom perspective view of the bearing segment.

[0075] FIG. 4 is a schematic representation including both a partial side cross-sectional view and a top view of a ball or socket of a bearing segment having multiple radii of curvature.

[0076] FIGS. 5A-5D are various views of an axial bearing and a bearing segment of the axial bearing. FIG. 5A is a schematic front view of the axial bearing. FIG. 5B is a topAtty Docket No.: 49379-0274WO1

[0077] perspective view of the bearing segment. FIG. 5C is a side cross-sectional view of the bearing segment. FIG. 5D is a bottom perspective view of the bearing segment.

[0078] FIG. 6 is a side cross-sectional view of a bearing segment having a ball surface that extends beyond a socket surface.

[0079] FIG. 7 is a side cross-sectional view of a releasable unitary bearing cartridge. FIGS. 8A and 8B are views of a bearing segment having a bearing pad that defines a circumferential groove.

[0080] FIG. 9 is a perspective cross-sectional view of a bearing segment having a convex bearing pad.

[0081] FIG. 10 is a perspective view of a spherical bearing pad of a bearing segment. FIGS. 11A-11H are various views of a bearing pad oil feed system including an inlet adapter assembly. FIG. 11 A is a partial cross-sectional view of the bearing pad oil feed system. FIG. 1 IB is a perspective view of the inlet adapter assembly. FIG. 11C is a side cross-sectional view of the inlet adapter assembly. FIG. 1 ID is a perspective view of a bearing pad and a feed plate of the bearing pad oil feed system. FIG. 1 IE is a detail perspective view of the feed plate on the bearing pad. FIG. 1 IF is a detail side cross-sectional view of the feed plate on the bearing pad. FIG. 11G is a detail perspective view of the feed plate. FIG. 11H is detail side cross-sectional view of the feed plate on the bearing pad.

[0082] FIG. 12 is a side cross-sectional view of a thrust bearing pad oil feed system. FIG. 13 is a side cross-sectional view of a bearing pad oil feed system.

[0083] FIGS. 14A and 14B are views of a bearing pad oil feed system. FIG. 14A is a perspective cross-sectional view of the bearing pad oil feed system. FIG. 14B is atop cross-sectional view of possible positions of the bearing pad oil feed system.

[0084] Like reference symbols in the various drawings indicate like elements.

[0085] DETAILED DESCRIPTION

[0086] One aspect of the present invention relates to a tiltable plain bearing segment assembly designed to improve the performance and durability of bearings used in turbine applications (e.g., wind turbines, tidal turbines, etc.).

[0087] Ball-and-socket bearing systems designed for high-speed, low-load applications may present certain challenges when applied to wind turbines. For example, the concentrated load on a single spot can lead to excessive mechanical stress and wear on the pad, ball, and socket, resulting in a reduced lifespan and increased maintenance costs.Atty Docket No.: 49379-0274WO1

[0088] Additionally, the need for larger and more robust components to mitigate these issues in turbine applications leads to material waste and higher production costs.

[0089] In various implementations, the tiltable plain bearing segment assembly has a monolithic socket-pad assembly, where the socket is integrated into the pad, forming a single, unified component. This integration helps reduce the number of separate parts to two (pad and ball, with the socket being part of the pad), simplifying the assembly process and reducing the risk of errors. The integrated design can also improve load distribution, reducing fatigue on both the pad and the ball, and resulting in a more even distribution of stresses, thereby increasing the overall potential lifespan of the bearing.

[0090] From a manufacturing perspective, the components described herein can be produced using conventional machining and manufacturing techniques, such as CNC machining and grinding, without the need for specialized equipment or expertise. This reduces production costs and simplifies the manufacturing process.

[0091] Referring first to FIG. 1, wind turbine system 100 includes a nacelle 102, turbine blades 104. a hub 106, and a tower 108. The nacelle 102, the turbine blades 104. and the hub 106 are part of a rotor assembly that sits atop the tower 108. Turbine system 100 generates electricity from wind and may float off-shore or be land-based. The nacelle 102 can also include a yaw mechanism (not shown) that allows it to rotate to face the wind direction.

[0092] Referring to FIG. 2, nacelle 102 has a housing 110 enclosing functional subsystems of the turbine system, including a shaft 202 connecting the hub 106 to an electrical generator 204, one or more radial bearings 206 (e.g., journal bearings) supporting the shaft, and / or one or more axial bearings 208 (e.g., thrust bearings) resisting axial loads applied to the hub 106. The bearings receive and support loads of the shaft 202 while allowing the shaft 202 to move as desired in at least one degree of freedom.

[0093] Kinetic energy from wind interfacing with the turbine blades 104 causes the shaft 202 to rotate. The generator 204 is coupled with the shaft 202 and is configured to convert the kinetic energy to electrical energy. In some implementations, the generator 204 includes a gearbox connecting the shaft to the generator, e.g., to increase the rotational speed at the generator 204.

[0094] The radial bearings 206 include a first radial bearing 206a and a second radial bearing 206b spaced apart along the shaft 202. The radial bearings 206 are configured to bear radial loads of the shaft 202, such as loads generally applied in a radial direction thatAtty Docket No.: 49379-0274WO1

[0095] is not parallel to the longitudinal axis of the shaft 202. including the weight of the rotating components. The axial bearings 208 include a first axial bearing 208a and a second axial bearing 208b. The axial bearings 208 are configured to bear axial loads of the shaft 202, such as loads generally applied in an axial direction parallel to the longitudinal axis of the shaft 202. The shaft 202 has a thrust collar 210 located, in the axial direction, between the first axial bearing 208a and the second axial bearing 208b. Axial loads in a direction toward the turbine blades 104 are supported by the first axial bearing 208a, and axial loads in a direction toward the generator 204 are supported by the second axial bearing 208b. In many cases, the axial loads pushing the shaft toward the generator are the larger axial loads and, in some cases, the first axial bearing 208a may be omitted or designed for much lower loads.

[0096] Referring to FIGS. 3A-3E, a radial bearing 300 (FIG. 3A) includes multiple radial bearing segment assemblies (or “bearing segments,” for short), such as a bearing segment 302 having a bearing pad 304, a pad support 306, and / or a seat 308 (FIG. 3B). While this example generally refers to a radial bearing application, one or more aspects of the bearing segment 302 can also be included in other types of bearings or bearing segments (e.g., those used in axial and / or thrust bearing applications, etc.) in various implementations.

[0097] The bearing pad 304 is a slide bearing pad with two opposite broad sides including a bearing side 310 and a pivot side 312. The bearing side 310 has a bearing surface 314 configured to form a bearing gap in cooperation with a load surface (e.g., the shaft 202 in FIG. 2) applying a load against the bearing side 310 at a differential speed through a film of liquid. The pivot side 312 defines a socket 316 behind a central portion of the bearing side 310. The socket 316 has an inner surface 318 (or “socket surface”) facing towards the pad support 306. In various implementations, the socket 316 is defined by a closed surface (e.g., a surface void of apertures) of the bearing pad 304.

[0098] The pad support 306 has a ball surface 320 extending into the socket 316 and bearing against the socket surface 318 to form a ball-socket interface 322, such that the load applied against the bearing side 310 is transmitted through the ball-socket interface 322 while allowing some tilting of the bearing pad 304 with respect to the pad support 306 under load, about a pivot center 323 defined by the ball-socket interface 322 in a plane containing the pivot center. According to various implementations, the ball surface 320 and / or the socket surface 318 defines a radius of curvature that varies across the ball-socket interface 322. Additionally, or alternatively, the ball-socket interface 322Atty Docket No.: 49379-0274WO1

[0099] is configured such that the pivot center moves slightly as the bearing pad 304 tilts with respect to the pad support 306. Thus, the pivot center can be an instantaneous pivot center defined by the ball-socket interface 322 with the bearing pad 304 at a particular tilt orientation relative to the pad support 306. In some non-limiting examples, a maximum amount of tilt of the bearing pad 304 is less than 2 degrees. In some cases, the maximum amount of tilt is less than 1 degree (e.g., about 0.8 degrees).

[0100] If the radius of curvature is uniform (like a perfect sphere) across the ball-socket interface 322, the pivot center will remain fixed as the bearing pad 304 tilts (e.g., in directions 324 indicated in FIG. 3B) relative to the pad support 306. However, if the radius of curvature varies across the ball-socket interface 322, the pivot center may shift as the bearing pad 304 pivots.

[0101] In some examples, the socket 316 spans a lateral distance, rim to rim across the pivot side 312 of the pad, that is at least 20 percent, preferably at least 50 percent, of an overall length of the bearing surface 314 in a direction of relative motion at the bearing surface 314. Furthermore, in some examples, the ball-socket interface 322 includes at least a point that is nearer the bearing surface 314 than to the pivot center.

[0102] The seat 308 holds pad support 306. In some implementations, the pad support 306 is a domed disc that includes a disc portion and a dome portion. The ball surface 320 is an upper surface of the dome portion. In some examples, the dome portion extending into the socket 316 has an overall height (e.g., referring to the associated coordinate system, the overall height is in the x-z direction) that is less than 60 percent of the overall height of the bearing pad 304 along a central axis of the dome portion. In a non-limiting example, the overall height of the dome portion is about 20 millimeters, and the overall height of the bearing pad 304 is about 110 millimeters. The disc portion is at least partially disposed within a central portion of the seat 308, and the dome portion extends from the disc portion toward the pad support 306. As discussed herein with reference to FIG. 9, the bearing pad 304 can be compliantly connected to the seat 308 (e.g., on opposite sides of the ball surface 320), such that the bearing pad 304, the pad support 306, and the seat 308 form a unitary bearing cartridge (e.g., unitary bearing cartridge 914 in FIG. 9). The unitary bearing cartridge is removable (as a unit) from the radial bearing 300.

[0103] As indicated in FIG. 3D, in some cases the ball surface 320 and / or the socket surface 318 features an anti-wear coating 330 covering the surface. The layer of anti-Atty Docket No.: 49379-0274WO1

[0104] wear coating 330 may have a total thickness of between 0.1 and 10 microns in a direction of a radius of curvature of the ball-socket interface 322.

[0105] Referring to FIG. 4, a surface 400 of a ball or socket of a bearing segment has multiple radii of curvature. The surface 400 has a central region 402 defining a central radius of curvature Rl. The central region 402 is surrounded by an intermediate region 404 defining an intermediate radius of curvature R2 different than the central radius of curvature Rl. The intermediate region 404 is surrounded by an outer region 406 defining an outer radius of curvature R3 different than the intermediate radius of curvature R2. The intermediate region 404 extends between the central region 402 and the outer region 406. In some examples, an overall surface area of the outer region 406 is smaller than the overall surface area of each of the central region 402 and the intermediate region 404.

[0106] The central region 402 transitions to the intermediate region 404 at transition T1 (e.g., a smooth transition), which is at a distance dl from a center 408 of the surface 400. The intermediate region 404 transitions to the outer region 406 at transition T2 (e.g., a smooth transition), which is at a distance d2 from the center 408.

[0107] The surface 400 has a radius R4, e.g., extending from the center 408 to an outermost extent of the outer region 406, as indicated in FIG. 4. According to some implementations, the transition T1 from the central region 402 to the intermediate region 404 occurs at a distance dl that is between 20 percent and 85 percent of the radius R4. In some implementations, the transition T2 from the intermediate region 404 to the outer region 406 occurs at a distance d2 that is between 80 percent and 99.9 percent of the radius R4.

[0108] In a non-limiting example, the distance dl is about 160 millimeters, the distance d2 is about 210.5 millimeters, and the radius R4 is about 220 millimeters. In this example, the central radius of curvature Rl is about 200 millimeters, the intermediate radius of curvature R2 is about 199.375 millimeters, and the outer radius of curvature R3 is about 10 millimeters.

[0109] In the examples described with reference to FIG. 4, the surface 400 of the ball or the socket has three discrete radii of curvature, while the other has a constant radius of curvature. In other examples, either the ball surface or the socket surface has a continuously variable radius of curvature, or a central region with a constant radius of curvature surrounded by a region of continuously variable curvature.Atty Docket No.: 49379-0274WO1

[0110] Referring back to FIG. 3B, an angle theta is an included angle defined by the overall bearing surface 314, an angle alpha is an included angle defined by an overall ball surface 320, and an angle beta is an included angle defined by the overall socket surface 318. In some non-limiting examples, the angle alpha ranges from 40 degrees to 75 degrees. In some non-limiting examples, the angle alpha ranges from 60 degrees to 70 degrees (e.g.. about 67 degrees). In a non-limiting example, the angle theta is about 35 degrees, the angle alpha is about 67 degrees, and the angle beta is about 16.7 degrees.

[0111] Referring to FIGS. 5A-5D, an axial bearing 500 (also referred to herein as a thrust bearing) (FIG. 5A) includes multiple axial bearing segments, such as a bearing segment 502 having a bearing pad 504 and a pad support 506. While this example generally refers to an axial bearing application, one or more aspects of the bearing segment 502 can also be included in other types of bearings or bearing segments (e.g., those used in radial bearing applications) in various implementations.

[0112] The bearing pad 504 is a slide bearing pad with two opposite broad sides including a bearing side 508 and a pivot side 510. The bearing side 508 has a bearing surface 512 configured to form a bearing gap in cooperation with a load surface (e.g., the thrust collar 210 in FIG. 2) applying a load against the bearing side 508 at a differential speed through a film of liquid. The pivot side 510 defines a socket 514 behind a central portion of the bearing side 508. The socket 514 has an inner surface 516 (or ‘‘socket surface7’) facing towards the pad support 506.

[0113] The pad support 506 has a ball surface 518 extending into the socket 514 and bearing against the socket surface 516 to form a ball-socket interface 520, such that the load applied against the bearing side 508 is transmitted through the ball-socket interface 520 while allowing some tilting of the bearing pad 504 with respect to the pad support 506 under load, about a pivot center defined by the ball-socket interface 520. According to various implementations, the ball surface 518 or the socket surface 516 defines a radius of curvature that varies across the ball-socket interface 520. Additionally, or alternatively, the ball-socket interface 520 is configured such that the pivot center moves slightly as the bearing pad 504 tilts with respect to the pad support 506. Thus, the pivot center can be an instantaneous pivot center defined by the ball-socket interface 520 with the bearing pad 504 at a particular tilt orientation relative to the pad support 506.

[0114] Referring to FIG. 6, a bearing segment 600 includes a bearing pad 602 and a pad support 604. In this example, a ball surface 606 of the pad support 604 laterally extends beyond the socket surface 608 of the bearing pad 602.Atty Docket No.: 49379-0274WO1

[0115] The ball surface 606 or the socket surface 608 defines a radius of curvature that varies across the ball-socket interface 610. As shown in FIG. 6 the ball surface 606 has a central ball region 612 defining a central ball radius of curvature, surrounded by an outer ball region 614 defining an outer ball radius of curvature different than the central ball radius of curvature. In the illustrated example, the outer ball radius of curvature is smaller than the central ball radius of curvature. The central ball region 612 and the outer ball region 614 blend together in a smooth transition. Alternatively, the socket can be configured with central 616 and outer 618 regions with differing curvature, in some cases transitioning smoothly.

[0116] In a non-limiting example, the central region of the ball surface 606 and / or socket surface 608 defines a central radius of curvature of about 200 millimeters, and the outer region of the ball surface 606 an / or the socket surface 608 defines an outer radius of curvature of about 10 millimeters.

[0117] Referring to FIG. 7, a bearing segment 700 includes a bearing pad 702, a pad support 704, a seat 706, and one or more connectors 708. The seat 706 holds the pad support 704. The bearing pad 702 is compliantly connected to the seat 706 via the connectors 708. Each of the connectors 708 include an elongated structure 710 coupled, at opposite ends, with the bearing pad 702 and the seat 706. The connectors 708 also include spring mechanisms 712 (and / or other compliant mechanism), enabling a compliant connection between the bearing pad 702 and the seat 706.

[0118] In the illustrated example, the connectors 708 are located on opposite sides of the ball surface, such that the bearing pad 702, the pad support 704, and the seat 706 form a unitary bearing cartridge 714. The unitary bearing cartridge 714 defines a releasable attachment point 716 arranged to connect the unitary bearing cartridge 714 to a tool (not shown) to remove the bearing cartridge 714 as a unit in a direction parallel to the load surface. The bearing pad 702 shown in FIG. 7 is a radial bearing pad. In other examples, the bearing pad can be a thrust bearing pad. The connectors 708 can be threaded bolts and the springs 712 can be coil springs or Belleville washers that provide a preload to hold the ball against the socket but allow some relative movement under load. The principal purpose of the connectors 708 is to hold the components of the segment 700 together for insertion and removal. Once the segment 700 is installed, the connectors 708 are no longer necessary'. In applications where the pad and ball structure can be removed by an appropriate fixture that holds them together, the connectors 708 can be omitted. InAtty Docket No.: 49379-0274WO1

[0119] another example (not shown), the pivot side of the slide bearing pad bears against a back side of a ball insert disposed within a socket of the pad support.

[0120] Referring to FIGS. 8 A and 8B, a bearing segment 800 includes a bearing pad 802 and a pad support 804. The bearing pad 802 defines a groove 806 formed circumferentially betw een a bearing side 808 and a pivot side 810 of the bearing pad 802 and extending about an entire perimeter of the pad. The purpose of this undercut around the perimeter of the bearing pad 802 is to allow some flexibility of the edges of the pad 802 to avoid load concentrations. For example, the groove 806 can be a waist groove and / or a neck groove. In some implementations, the groove 806 is located between the bearing side 808 and a point on the ball-socket interface 812 that is nearest the bearing side 808.

[0121] As shown, the bearing pad 802 includes an upper wall 814 and a lower wall 816 that flare outwardly in opposite directions from the smallest circumference of the groove 806. The upper wall 814 includes at least a portion of the bearing side 808. The lower wall 816 includes at least a portion of the pivot side 810. The smallest circumference of the groove 806 delimits the upper wall 814 from the lower wall 816. An underside 818 of the upper wall 814 has a positive slope. A topside 820 of the lower wall 816 has a negative slope.

[0122] In some examples, the inner radius 822 of the groove 806 is at least 5 millimeters or higher. A depth 824 of the groove 806, from the edge of the bearing pad 802, is preferably at least 4 percent of an overall lateral extent of the bearing surface, or in this example, 14 millimeters.

[0123] Referring to FIG. 9, a bearing segment 900 includes a convex bearing pad 902, a pad support 904, and a seat 906. The convex pad 902 has a convex bearing surface 908.

[0124] Referring to FIG. 10, a spherical bearing pad 1000 has a bearing surface 1002 with curvature in each of two orthogonal directions. In some examples, the bearing segment 900 in FIG. 9 can include the spherical bearing pad 1000 instead of the convex bearing pad 902.

[0125] Referring to FIGS. 11A-11H, a bearing pad oil feed system 1100 includes a radial pad 1102 and an inlet adapter assembly 1104.

[0126] Referring first to FIGS. UD and HE, the radial pad 1102 has a feed plate 1106, which is screwed and doweled in place on the leading edge of the radial pad 1102 to define an oil feed slot 1108 at the leading edge of the curved bearing surface 1110. In this example, bearing surface 1110 is arcuate as the bearing pad is a radial bearing padAtty Docket No.: 49379-0274WO1

[0127] that slides against the other cylindrical surface of a shaft, and the slot 1108 extends along a flat, leading edge of the bearing surface 1110. In another example (not shown), the bearing surface is flat and the bearing pad comprises a thrust bearing pad. The feed plate 1106 can be removed, if required, for servicing. Referring also to FIG. 11G, the feed plate 1106 has two feed galleries 1112, one near each end, which feed the oil feed slot 1108. In other examples, the feed plate 1106 can have one feed gallery. Bleed grooves 1114 extend through to the pad sides at either end of the slot 1108 to flush debris from the slot 1108 as needed, or to regulate flow into the fluid film interface. The feed plate 1106 is supported by a ledge 1116 of the radial pad 1102, as shown in FIG. 1 IF.

[0128] As shown in FIG. 11H. the two feed galleries 1112 are arranged for hydraulic communication with respective lubrication oil inlets 1118 on either lateral side of the pad 1102, to allow the pad 1102 to be fed from either side depending on the machine setup. The unused feed will be plugged with a set screw at the unused oil inlet 1118. The active oil inlet 1118 is connected to one of the feed galleries 1112 via intersecting passages 1120 defined in the pad 1102.

[0129] Refernng next to FIGS. 11 A-l 1C, the radial pad 1102 is fed by the inlet adapter assembly 1104 threaded into a tapped hole 1122 in a stationary endplate 1124 forming a wall of the cavity7in which the bearing pad 1102 tilts. By endplate we do not mean to imply that the endplate is itself removable. It may be a stationary wall of the bearing housing. The connection between the inlet adapter assembly 1104 and hole 1122 is sealed with a bonded seal 1126 (e.g., at surface 1127). Hole 1122 in the endplate 1124 is aligned with inlet 1118 in the pad 1102, such that one end of the coupler 1128 of the inlet adapter assembly 1104 extends into a smooth bore of the pad inlet when the inlet adapter assembly 1104 is installed in the endplate 1124. The other end of the coupler 1128 is disposed within a smooth bore of a cartridge 1130 of the inlet adapter assembly 1104, which defines a hole leading from a threaded pipe fitting connection 1132 at a hex end of the cartridge 1130, such that once the inlet adapter assembly 1104 is installed a pipe or hose can be attached to supply pressurized oil to the coupler 1128 through the cartridge 1130. From the inlet adapter assembly 1104 oil enters the radial pad 1102 through oil inlet 1118 and then is communicated to the bearing face oil feed slot 1108 by cross channel 1120. Inlet 1118 is tapped inward of the smooth bore to allow it to be plugged with a socket set screw, if needed.

[0130] As shown in FIG. 11C. the inlet adapter assembly 1104 is a pre-assembled unit consisting of the cartridge 1130 and coupler 1128, sometimes referred to herein as aAtty Docket No.: 49379-0274WO1

[0131] dolley. The dolley is elongated and hollow, for communicating lubricating oil from one end to the other. Each end of the dolley has a partially spherical surface into which is set an o-ring 1134 disposed in an appropriate groove. The shape of each dolley end, and the positioning of the o-ring 1134, allows the dolley to both translate axially, and tilt in any direction about an axis perpendicular to its longitudinal axis, while maintaining a seal against the smooth bore surfaces in which the spherical ends rest. This allows the coupler 1128 to maintain a pressurized oil connection throughout the range of tilt motion of the pad in use. The o-ring 1134 connections also allow the dolley to accommodate some amount of twisting of one end connection with respect to the other about its longitudinal axis, as such rotation will occur due to the dolley extending along a direction parallel with a tilt axis of the bearing. The cartridge 1130 has an external thread 1136 for mounting to the endplate 1124 or other static part of the bearing housing, and an internal thread 1138 for accepting a pipe or hose fitting. The cartridge 1130 has an external hex 1140 on the end for installation via a spanner or socket. The smooth bore 1142 of the cartridge 1130 has a groove for an internal spring clip 1144 fitted to prevent the coupler 1128 or dolley 1128 from falling out prior to installation. Small pin hole 1146 is designed to allow the clip 1144 to be removed using a pin to remove the dolley 1128.

[0132] While the above oil feed system has been described with respect to feeding oil to a leading edge slot of a tilting bearing pad face to maintain a hydrodynamic pressure film during shaft rotation, in other examples the system feeds a central aperture defined in the bearing face to generally force the two relatively sliding surfaces apart at low or zero speed differentials, a process known as ‘jacking’. Such ajacking oil feed system would also advantageously use a pad oil inlet extending into a side of the pad, as discussed above.

[0133] Referring to FIG. 12, a similar coupler 1128 can also be used to feed a thrust bearing pad 1202. The thrust bearing pad 1202 has a pivot side configured to pivot on a cartridge 1204 (e.g., a removable thrust cartridge), w hich is coupled with a cartridge mounting ring 1206. Opposite the pivot side, the thrust bearing pad 1202 has a bearing side that faces a thrust collar 210 (e.g.. thrust collar 210 in FIG. 2). In this example, an inlet adapter assembly 1104 as shown in FIGS. 11B and 11C is threaded into a cover plate 1210, with the dolley 1128 extending into the pad 1202 in a direction parallel to the pivot axis of the pad 1202. The dolley 1128 spans a radial gap betw een the pad 1202 and the cover plate 1210. The dolley 1128 has sufficient clearance to the bores in the pad 1202 and cover plate 1210 to allow the desired tilting of the pad 1202 on theAtty Docket No.: 49379-0274WO1

[0134] cartridge 1204. One or more channels within the pad 1202 form a pathway to communicate lubricating oil received through the dolley 1128 to the lubrication slot at the leading edge of the pad 1202.

[0135] Referring to FIG. 13, a similar coupler 1128 can also be used to feed a bearing pad 1302 from an associated pad support 1304. In this example, an inlet adapter assembly 1104 as shown in FIGS. 1 IB and 11C is threaded into the pad support 1304, with the dolley 1128 extending into the pad 1302 in a direction perpendicular to the pivot axis of the pad 1302. The dolley 1128 has sufficient clearance to the bores in the pad 1302 and cartridge to allow the desired tilting of the pad 1302 about the ball. While the inlet is shown forward of the ball, in a shaft rotation direction, the inlet may instead be placed alongside the ball, or otherwise as needed to provide clearance for fasteners connecting ball support 1304 and pad 1302, as shown in FIG. 7. A cross-channel 1306 communicates the lubricating oil from the inlet to the lubrication slot at the leading edge of the pad 1302.

[0136] Referring to FIG. 14A, a coupler 1128 can be used without an associated cartridge to feed a bearing pad 1402 from an associated pad support 1404 via a bore 1406 in the pad support 1034. The bore 1406 extends toward the pad 1402 from an inlet 1408 at a bottom surface 1410 of the ball support 1404. As previously discussed, the pad 1402 and the ball support 1404 can be connected to form a module (e g., the unitary bearing cartridge 714 in FIG. 7). In some examples, when such a module is installed in a bearing housing (not shown), the inlet 1408 can be aligned with a hole in the housing, such that lubrication fluid can flow through the housing and into the ball support 1404 via the inlet 1408 and the bore 1406. One end of the coupler 1128 extends into the pad 1402 in a direction perpendicular to the pivot axis of the pad 1402. An opposite end of the coupler 1128 extends into the pad support 1404 in the direction perpendicular to the pivot axis of the pad 1402. The coupler 1128 receives the lubrication fluid via the bore 1408 and communicates the lubrication fluid to a bore 1412 in the pad 1402. The bore 1412 communicates the lubrication fluid to a cross-channel 1414 in the pad 1402, which then communicates the lubricating fluid to the lubrication slot at the leading edge 1416 of the pad 1402.

[0137] Referring to FIG. 14B, a position of the coupler 1128 (corresponding to the position shown in FIG. 14A) and various alternative positions 1418 are shown. The coupler 1128 is preferably positioned in the forward half of the pad, to facilitate routing the lubricating fluid to the forward slot, as indicated in FIG. 14B.Atty Docket No.: 49379-0274WO1

[0138] While a number of examples have been described for illustration purposes, the foregoing description is not intended to limit the scope of the invention, which is defined by the scope of the appended claims. There are and will be other examples and modifications within the scope of the following claims.

Claims

Atty Docket No.: 49379-0274WO1WHAT TS CLAIMED IS:

1. A tiltable plain bearing segment assembly (302), comprising:a slide bearing pad (304) with two opposite broad sides including a bearing side (310) and a pivot side (312), the bearing side (310) having a bearing surface (314) configured to form a bearing gap in cooperation with a load surface applying a load against the bearing side (310) at a differential speed through a film of liquid, the pivot side (312) defining a socket (316) therein behind a central portion of the bearing side (310); anda pad support (306) having a ball surface (320) extending into the socket (316) and bearing against an inner surface (318) of the socket (316) to form a ball-socket interface (322), such that the load applied against the bearing side (310) is transmitted through the ball-socket interface (322) while allowing some tilting of the slide bearing pad (304) with respect to the pad support (306) under load, about a pivot center (323) defined by the ballsocket interface (322);wherein either the ball surface (320) or the inner surface (318) of the socket (316) defines a radius of curvature that varies across the ball-socket interface (322).

2. The tiltable plain bearing segment assembly (302) of claim 1, wherein the ball-socket interface (322) is configured such that the pivot center (323) moves as the slide bearing pad (304) tilts with respect to the pad support (306), and / or wherein the pad support (306) comprises a support seat (308) extending laterally beyond the ball surface (320).

3. The tiltable plain bearing segment assembly (302) of claim 1 or 2, wherein the pad support (306) comprises a domed disc, in particular a domed disc comprising a disc portion and a dome portion, wherein the ball surface (320) is an upper surface of the dome portion, particularly wherein the tiltable plain bearing segment assembly (302) comprises a support seat (308) holding the pad support (306), and wherein the support seat (308) is fixedly coupled with the disc portion.

4. The tiltable plain bearing segment assembly (302) of any one of claims 1 to 3, wherein the socket surface (318) comprises a central socket region (402) defining a central socket radius of curvature, surrounded by an outer socket region (406) defining an outerAtty Docket No.: 49379-0274WO1socket radius of curvature different than the central socket radius of curvature, particularly wherein the outer socket radius of curvature is larger than the central socket radius of curvature, and particularly wherein the central socket region (402) and the outer socket region (406) blend together in a smooth transition.

5. The tiltable plain bearing segment assembly (302) of claim 4, wherein the socket surface (318) further comprises an intermediate socket region (404) extending between the central socket region (402) and the outer socket region (406), wherein the intermediate socket region (404) defines an intermediate socket radius of curvature that is different than the central socket radius of curvature and the outer socket radius of curvature, particularly wherein the intermediate ball radius of curvature is larger than the central socket radius of curvature, particularly wherein the outer socket radius of curvature is larger than the intermediate socket radius of curvature, and particularly wherein the central socket region (402), the intermediate socket region (404), and the outer socket region (406) blend together in smooth transitions.

6. The tiltable plain bearing segment assembly (302) of any one of claims 1 to 5, wherein the ball surface (320) comprises a central ball region (402) defining a central ball radius of curvature, surrounded by an outer ball region (406) defining an outer ball radius of curvature different than the central ball radius of curvature, particularly wherein the outer ball radius of curvature is smaller than the central ball radius of curvature, and particularly wherein the central ball region (402) and the outer ball region (406) blend together in a smooth transition.

7. The tiltable plain bearing segment assembly (302) of claim 6, wherein the ball surface (320) further comprises an intermediate ball region (404) extending between the central ball region (402) and the outer ball region (406), and wherein the intermediate ball region (404) defines an intermediate ball radius of curvature that is different than the central ball radius of curvature and the outer ball radius of curvature, particularly wherein the intermediate ball radius of curvature is smaller than the central ball radius of curvature, particularly wherein the outer ball radius of curvature is smaller than the intermediate ballAtty Docket No.: 49379-0274WO1radius of curvature, and particularly wherein the central ball region (402), the intermediate ball region (404), and the outer ball region (406) blend together in smooth transitions.

8. The tiltable plain bearing segment assembly (302) of any one of claims 1 to 7, wherein at least one of the ball surface (320) or the socket surface (318) comprises an antiwear coating (330) overlaying a substrate, and / or wherein the socket surface (318) is void of apertures, and / or wherein the slide bearing pad (304) is compliantly connected to the pad support (306) on opposite sides of the ball surface (320), such that the slide bearing pad (304) and pad support (306) form a unitary bearing cartridge (714).

9. The tiltable plain bearing segment assembly (302) of any one of claims 1 to 8, further comprising a fluid coupling (1128) connecting the slide bearing pad (304) and the pad support (306) and configured to supply a flow of lubricating fluid to the bearing side (310) of the slide bearing pad (304), in particular wherein the fluid coupling (1128) comprises a hollow rigid connector extending into respective bores in each of the slide bearing pad (304) and the pad support (306) and configured to angulate during tilting of the slide bearing pad (304) with respect to the pad support (306).

10. The tiltable plain bearing segment assembly (302) of any one of claims 1 to 9, wherein the slide bearing pad (304) is a thrust bearing pad (504) and wherein the bearing surface (314) is flat.

11. The tiltable plain bearing segment assembly (302) of any one of claims 1 to 9, wherein the slide bearing pad (304) is a radial bearing pad (304) and wherein the bearing surface (314) is concave.

12. The tiltable plain bearing segment assembly (302) of any one of claims 1 to 11, wherein the slide bearing pad (304) defines a groove (806) formed about an entire perimeter of the slide bearing pad (304) between the bearing side (310) and the pivot side (312).Atty Docket No.: 49379-0274WO113. The tiltable plain bearing segment assembly (302) of claim 12, wherein: the groove (806) is located between the bearing side (310) and a point on the ballsocket interface (322) that is nearest the bearing side (310); and / orthe groove (806) extends inward to a circular neck defined by the slide bearing pad (304); and / orthe groove (806) is defined between tapered surfaces and narrows in width from an outer opening of the groove (806); and / orthe groove (806) has a depth, measured across a width of the slide bearing pad (304), that is at least 4 percent of a lateral extent of the width of the slide bearing pad (304).

14. A bearing support system (100), comprisinga load surface (202); andmultiple tiltable plain bearing segment assemblies (302) according to any of claims 1 to 13, arranged to each bear against the load surface (202) to support an applied load at a speed differential between the load surface (202) and the bearing surfaces (314) of the tiltable plain bearing segments (302).

15. The bearing support system (100) of claim 14, wherein:the load surface (202) is a cylindrical surface of a rotor (202), and wherein the bearing surfaces (314) are curved, particularly wherein the bearing surfaces (314) are concave (314), convex (908), or spherical (1002); orthe load surface (202) is a flat surface of an axial load collar (210) of a rotor (202), and wherein the bearing surfaces are flat; and / orthe multiple tiltable plain bearing segment assemblies (302) comprise at least six tiltable plain bearing segment assemblies (302).

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