System and method for fluid dynamic bearing

Abstract

Disclosed herein are systems and methods for a hydrodynamic bearing (900, 700, 500, 1500) that can be included in an X-ray source (300, 104) of an X-ray imaging system (100), such as a CT imaging system. The hydrodynamic bearing (900, 700, 500, 1500) includes a stationary component and a rotating component configured to be attached to an X-ray source target (406, 310). A plurality of grooves (506, 416) formed in the stationary component are arranged in a groove pattern and are structured to generate pressure in a fluid interface (320, 408) during rotation of the rotating component, wherein one or more of a groove depth (704, 704), a groove angle (1140), a groove cross-sectional shape, a groove to land ratio, a diameter of the rotating component, and a diameter of the stationary component varies axially according to an expected thermal and structural deformation pattern (550, 650).

Description

Technical Field

[0001] This manual pertains to hydrodynamic bearings. Background Technology and Summary of the Invention

[0002] Hydrodynamic bearings, also known as liquid metal bearings, spiral groove bearings, or journal bearings, involve using liquid metal as a lubricant. This lubricant is placed in the gap between the shaft and the sleeve. Compared to other bearing types such as contact bearings or ball bearings, this reduces friction and extends the bearing's service life. These advantages of hydrodynamic bearings make them suitable for a variety of applications, such as medical imaging (e.g., computed tomography scans, X-ray imaging, etc.).

[0003] Due to the thermal properties of the materials constituting the shaft and sleeve, and the temperature profile generated under operating conditions, the shaft and / or sleeve of a hydrodynamic bearing may expand or contract. Such expansion and / or contraction can alter the geometry of the clearance between the shaft and sleeve, resulting in uneven clearance. That is, this clearance may vary along the axial direction of the hydrodynamic bearing, leading to a change in the flow pattern of the lubricant. Specifically, the net axial flow may change. Furthermore, the effects of this flow pattern change may include lubricant being pumped out of the bearing due to the change in flow pattern. Lubricant loss and the resulting insufficient bearing lubrication can lead to undesirable bearing dynamic characteristics, such as changes in stiffness and damping. In addition, other factors may exacerbate lubricant loss, including capillary forces due to sufficiently narrow clearances, rack rotation and centrifugal forces that cause changes in the liquid / gas (e.g., vacuum) interface, and lubricant squeeze flow that occurs without sufficient recovery pressure.

[0004] Therefore, this document discloses an embodiment of a hydrodynamic bearing that addresses at least some of the aforementioned problems. The hydrodynamic bearing may include: a rotating component; and a stationary component comprising a surface having a plurality of grooves arranged in a groove pattern and configured to generate pressure at a fluid interface during rotation of the rotating component, wherein one or more of the groove depth, the diameter of the rotating component, the groove-to-groove ratio, the groove cross-sectional shape, the groove angle, or the diameter of the stationary component varies axially according to a desired thermal and structural deformation mode.

[0005] In this way, lubricant loss due to heat and structural deformation of the shaft and / or sleeve under operating conditions (e.g., higher temperatures, higher loads, etc.) can be at least partially mitigated. For example, lubricant loss can be reduced or completely avoided because modifications to the shaft and / or sleeve (e.g., axially varying diameters and / or groove depths) offset the effects on pressure and lubricant flow patterns.

[0006] It should be understood that the above description of the invention is provided to present a series of concepts further described in the detailed embodiments in a simplified form. This is not intended to identify key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims following the detailed embodiments. Furthermore, the claimed subject matter is not limited to specific implementations that address any shortcomings pointed out above or in any part of this disclosure. Attached Figure Description

[0007] This disclosure will be better understood by referring to the following description of non-limiting embodiments, in which:

[0008] Figure 1 A perspective view of an exemplary computed tomography (CT) imaging system including an X-ray source is shown;

[0009] Figure 2 A schematic diagram of an exemplary CT imaging system including an X-ray source is shown;

[0010] Figure 3 A cross-sectional view of an exemplary X-ray source including a hydrodynamic bearing according to the present disclosure is shown;

[0011] Figure 4 A cross-sectional view of a portion of another exemplary X-ray source including a hydrodynamic bearing, according to this disclosure, is shown.

[0012] Figure 5 The expected thermal and structural deformation modes are shown;

[0013] Figure 6 The expected thermal and structural deformation modes are shown;

[0014] Figure 7 The thermal and structural deformation modes according to this disclosure and the corresponding hydrodynamic bearings are shown;

[0015] Figure 8 It shows Figure 7 The curves of thermal and structural deformation modes versus groove depth for corresponding hydrodynamic bearings;

[0016] Figure 9 The thermal and structural deformation modes according to this disclosure and the corresponding hydrodynamic bearings are shown;

[0017] Figure 10 It shows Figure 9 The curves of thermal and structural deformation modes versus groove depth for corresponding hydrodynamic bearings;

[0018] Figure 11 The shaft of the hydrodynamic bearing according to this disclosure is shown;

[0019] Figure 12 The shaft of the hydrodynamic bearing according to this disclosure is shown;

[0020] Figure 13 The shaft of the hydrodynamic bearing according to this disclosure is shown;

[0021] Figure 14 The shaft of the hydrodynamic bearing according to this disclosure is shown;

[0022] Figure 15 The shaft and sleeve of the hydrodynamic bearing according to this disclosure are shown; and

[0023] Figure 16 A flowchart of a method for manufacturing a hydrodynamic bearing according to the present disclosure is shown;

[0024] Figure 17 A graph showing the thermal and structural deformation modes versus groove depth of a corresponding hydrodynamic bearing according to this disclosure is presented. Detailed Implementation

[0025] The following description relates to a hydrodynamic bearing. The hydrodynamic bearing according to this disclosure may be included in an X-ray source or X-ray tube of an X-ray imaging system, such as a computed tomography (CT) imaging system. Figure 1 and Figure 2 An example of such an imaging system is illustrated in the text. Figure 3 and Figure 4 An example of an X-ray source is shown, including the hydrodynamic bearing of this disclosure. The hydrodynamic bearing of this disclosure can reduce lubricant (e.g., liquid metal) loss caused by the gap between a stationary component (e.g., a shaft) and a rotating component (e.g., a sleeve). Lubricant loss may be due to changes in the shape of the stationary and / or rotating components caused by thermal expansion or contraction due to temperature gradients, as well as elastohydrodynamics. Changes in the shape of the stationary and / or rotating components may additionally depend on structural loads and relative movement (e.g., rotation). Figure 5 and Figure 6An example of thermal and structural deformation modes within a hydrodynamic bearing caused by the operation of an X-ray source is shown. The anticipated changes in thermal and structural deformation modes may result from a specific heat distribution generated by relative rotational motion, which depends on the heat accumulated within the bearing, the rotational speed of the rotating components, the bearing geometry, and the corresponding lubricant flow pattern, leading to locations where heat accumulates disproportionately. Such thermal and structural deformation may alter the lubricant flow pattern (e.g., by changing local pressure), causing lubricant fluid to be pumped out of the conventional bearing. To reduce lubricant loss, the stationary and / or rotating components can be modified. More specifically, as an example of such modification, the depth of the herringbone groove in the stationary component can be axially varied according to the anticipated thermal and structural deformation based on its operating heat distribution and the load on the bearing. The groove depth can be as follows: Figure 12 As shown, it varies with the axial cross section, or as... Figures 7 to 10 The continuous variation is shown. For example, the profile of the trench depth can mirror the expected thermal and structural deformation patterns. Figures 7 to 10 and Figure 17 An example of a trench depth profile corresponding to the expected thermal and structural deformation mode is shown. In addition to modifying the trench depth, or as an alternative, the trench cross-sectional shape, the sill-to-groove ratio, and / or the trench angle can be modified to vary axially according to the expected thermal and structural deformation mode. Additionally or alternatively, such as Figure 11 As shown, the segments of the herringbone groove pattern can be made relatively longer than other segments. Additionally or alternatively, such as... Figure 13 As shown, some segments can be modified to be completely without grooves. Additional or alternative locations, such as... Figure 14 As shown, the outer diameter of the shaft can be modified to vary axially. Additionally or alternatively, such as... Figure 15 As shown, the inner diameter of the sleeve can be varied axially. In this way, the possibility of reduced load capacity, suboptimal stiffness and damping characteristics, and / or other consequences caused by lubricant loss from hydrodynamic bearings can be reduced (e.g., avoided). Furthermore, the number and / or complexity of seals in the system can be reduced because less fluid flow is directed at the seals. The method for manufacturing hydrodynamic bearings according to this disclosure... Figure 16 It is shown in the form of a flowchart.

[0026] It should be understood that the specific components and systems illustrated in the accompanying drawings and described in the following specification are exemplary embodiments of the inventive concept defined herein. For ease of discussion, the drawings are described in their entirety below. Therefore, similar elements may be referred to using similar reference numerals in this specification and will not be repeated.

[0027] Before further discussing the hydrodynamic bearings of the X-ray source, an example imaging system in which the X-ray source can be implemented is shown. Figure 1A schematic diagram of an embodiment of an X-ray imaging system 100 according to an exemplary embodiment is shown. This X-ray imaging system is configured to acquire raw image data and process the image data for display and / or analysis. It should be understood that various embodiments are applicable to numerous X-ray imaging systems that implement X-ray tubes, such as radiographic (RAD) imaging systems, mammography imaging systems, fluoroscopy imaging systems, tomography imaging systems, or computed tomography (CT) imaging systems. The following discussion of the X-ray imaging system 100 is merely an example of such a specific embodiment and is not intended to limit the modality.

[0028] The X-ray imaging system 100 may be configured as one or more of an interventional radiography imaging system, a mammography imaging system, a fixed or mobile RAD imaging system, etc. Specifically, the X-ray imaging system 100 is configured to image a subject 112 (such as a patient, an inanimate object, one or more manufactured parts) and / or foreign objects (such as dental implants, stents, and / or contrast agents present in the body). In one embodiment, the X-ray imaging system 100 includes a gantry 102, which may further include at least one X-ray source 104 configured to project an X-ray radiation beam for imaging the subject 112 lying on the examination table 114. Specifically, the X-ray source 104 is configured to project an X-ray radiation beam toward a detector assembly 108 positioned on the opposite side of the gantry 102. In some embodiments, the X-ray tube 104 is configured to traverse different angular positions around the subject 112 to acquire desired projection data. Therefore, the rack 102 and the components mounted thereon can be configured to rotate about the rotation center 106 for acquiring projection data, for example, at different energy levels. Alternatively, in an embodiment where the projection angle relative to the subject 112 varies over time, the mounted components can be configured to move along a generally curved path rather than along a circumference.

[0029] although Figure 1 A single X-ray source 104 is depicted, but in some embodiments, multiple X-ray tubes and detectors may be employed to project multiple X-ray radiation beams for acquiring projection data at different energy levels corresponding to the patient. In some embodiments, the X-ray source 104 can achieve dual-energy gemstone spectral imaging (GSI) via rapid peak kilovolt (kVp) voltage switching. In some embodiments, the X-ray detector employed is a photon-counting detector capable of distinguishing X-ray photons of different energies. In other embodiments, two sets of X-ray tubes and detectors are used to generate dual-energy projections, one set configured for low kVp and the other for high kVp. Therefore, it should be understood that the methods described herein can be implemented using both single-energy acquisition techniques and dual-energy acquisition techniques.

[0030] In some CT imaging system configurations, an X-ray tube projects a cone-shaped beam of X-ray radiation, which is collimated to lie in the XYZ plane of a Cartesian coordinate system and is often referred to as the "imaging plane." The X-ray beam passes through the object being imaged, such as a patient or subject. After being attenuated by the object, the X-ray beam strikes an array of detector elements. The intensity of the attenuated X-ray beam received at the detector elements depends on the attenuation of the beam by the object. Each detector element in the array generates a separate electrical signal, which is a measurement of the X-ray beam attenuation at the detector location. Attenuation measurements from all detector elements are acquired individually to produce the transmission distribution.

[0031] In some CT systems, a gantry is used to rotate the X-ray tube and detector assembly around the object to be imaged within the imaging plane, causing the angle at which the radiation beam intersects the object to continuously change. A set of X-ray beam attenuation measurements (e.g., projection data) from the detector assembly at a single gantry angle is referred to as a “view.” A “scan” of the object comprises a set of views acquired at different gantry angles or viewing angles during a single rotation of the X-ray tube and detector. It is conceivable that the benefits of the methods described herein stem from medical imaging modalities beyond CT; therefore, as used herein, the term “view” is not limited to the uses described above regarding projection data from a single gantry angle. The term “view” is used to mean a data acquisition whenever multiple data acquisitions from different angles exist (whether from CT, positron emission tomography (PET), or single-photon emission CT (SPECT) acquisitions), and / or any other modality (including modalities yet to be developed) and their combinations in fusion implementations.

[0032] Projection data is processed to reconstruct an image corresponding to a two-dimensional slice obtained through an object, or, in some examples, to reconstruct an image corresponding to a three-dimensional rendering of the object, the projection data includes multiple views or scans. One method for reconstructing an image from a set of projection data is known in the art as filtered backprojection. Transmitted and emitted tomography reconstruction techniques also include statistical iterative methods, such as MLEM and ordered subset expectation reconstruction techniques, as well as iterative reconstruction techniques. This method converts attenuation measurements from scans into integers called “CT numbers” or “Henness units,” which are used to control the brightness of the corresponding pixels on a display device.

[0033] Figure 2 The block diagram 200 shows Figure 1 Further details of the X-ray imaging system 100. (See below) Figure 2As shown, the X-ray imaging system 100 includes an X-ray source 104 configured to project a beam of X-rays 206 through a subject 112. The subject 112 may include a human subject, luggage, or other object to be scanned. The X-ray source 104 may be one or more X-ray tubes that generate X-rays 206 having an energy spectrum typically ranging from thirty (30) keV to two hundred (200) keV. The X-rays 206 pass through the subject 112 and, after attenuation, are incident on an array of detectors 208 of a detector assembly 108. Each detector module in the detector assembly 108 generates an analog electrical signal representing the intensity of the incident X-ray beam (i.e., the attenuated beam after passing through the subject 112). In one embodiment, the detector assembly 108 is a scintillator-based detector assembly, which can be implemented as an energy integration detector; however, it is also contemplated that a direct conversion detector or a photon counting detector (e.g., a CdTe, CZT, Si detector, etc.) can also be implemented.

[0034] X-ray imaging system 100 includes an X-ray controller 210 that provides power and timing signals to X-ray source 104. The X-ray imaging controller 100 may also include a gantry motor controller 212 that controls the rotational speed and position of gantry 102. In some examples, the X-ray imaging system 100 may include a table motor controller 226 configured to control the position of examination table 114 where the patient 112 is located (e.g., via one or more motors of examination table 114). The rotation of gantry 102 and the operation of X-ray source 104 are controlled by a computing device 216 of the X-ray imaging system 100. The computing device 216 may include a processor 222 configured to send and receive signals from one or more of the X-ray controller 210, gantry motor controller 212, and table motor controller 226. Furthermore, the computing device 216 may receive signals from detector assembly 108 and generate an image corresponding to the scanned patient 112. X-ray imaging system 100 may include image reconstructor 230, which is configured to receive sampled and digitized X-ray data (e.g., from a data acquisition system of computing device 216) and perform high-speed image reconstruction. The reconstructed image may be applied as input to computing device 216 and stored in storage device 218.

[0035] The computing device 216 communicates with the processor 222 to enable the operator to use the operator console 220 to control scanning parameters and view the generated images. That is, the operator console 220 includes some form of operator interface, such as a keyboard, mouse, voice-activated controller, or any other suitable input device, which allows the operator to control the X-ray imaging system 100 and view reconstructed images or other data from the computing device 216 on the display unit 232. Additionally, the operator console 220 allows the operator to store the generated images in a storage device 218, which may include a hard disk drive, floppy disk, optical disk, etc. The operator can also use the operator console 220 to provide commands and instructions to the computing device 216 to control the X-ray controller 210, which provides power and timing signals to the X-ray source 104.

[0036] Figure 3 A portion of the X-ray source 300 is shown. Figures 3 to 7 , Figure 9 , Figure 11 and Figures 13 to 15 The diagram provides a rotation axis 350 and a radial axis 352 for reference, wherein the rotation axis 350 may be parallel to the y-axis and the radial axis 352 may be parallel to the z-axis. Figure 3 The X-ray source 300 shown is used as Figure 1 and Figure 2 An example of the depicted X-ray source 104. Therefore, Figure 3 The X-ray source shown may include those from Figure 1 and / or Figure 2 The functional and / or structural features of the X-ray source 104 shown are illustrated, and vice versa. Furthermore, alternative embodiments combining features from one or more systems within the system are envisioned.

[0037] X-ray source 300 includes a housing 302 having a low-pressure package 304 (e.g., a vacuum package) formed therein. It should be understood that a low-pressure package refers to a pressure relatively low relative to atmospheric pressure (e.g., ambient pressure). Therefore, the pressure within the package may be less than atmospheric pressure.

[0038] X-ray source 300 includes a hydrodynamic bearing system 305 having a sleeve 306 and a shaft 308. One of the sleeve 306 and the shaft 308 can be a rotating component, and the other can be a stationary component. X-ray source target 310 can be coupled to the rotating component. In the illustrated example, the sleeve 306 is the rotating component, and the shaft 308 is the stationary component. However, embodiments in which the sleeve 306 is the stationary component and the shaft 308 is the rotating component are contemplated. In such an example, the X-ray source target 310 can be coupled to the shaft 308 instead of the sleeve 306. It should be understood that the motion indicated by the descriptive terms "stationary" and "rotating" refers to the relative motion between components. However, as previously mentioned, the X-ray source can be integrated into a moving structure. For example, in the use case of a CT imaging system, the X-ray source can be integrated into a rotating gantry. Thus, in a smaller scale frame of reference, the shaft is stationary relative to the sleeve, but in a larger scale frame of reference, both components exhibit similar rotational motion within the gantry. However, in alternative use cases, the X-ray source can be integrated into a stationary structure relative to a larger scale reference frame.

[0039] Shaft 308 is shown attached (e.g., fixedly coupled) to housing 302 at a first axial end 314. In some embodiments, shaft 308 may be attached to housing 302 or other suitable X-ray source components at a second axial end opposite to the first axial end 314. In this embodiment, the bearing system is configured as a straddle bearing system. However, system embodiments in which shaft 308 is coupled at only one axial end to form a cantilever arrangement have been contemplated.

[0040] The hydrodynamic bearing system 305 includes a plurality of hydrodynamic bearings, including a journal bearing 316, a first thrust bearing 318, and a second thrust bearing 319. The first thrust bearing 318 and the second thrust bearing 319 are positioned on opposite axial sides of the flange 342 of the shaft 308. However, the system may include… Figure 3 The view in the image is obscured by the additional bearing. Journal bearing 316 is designed to support radial loads, and thrust bearing 318 is designed to support axial loads. In this way, the load on sleeve 306 is controlled, enabling it to rotate efficiently, where efficiency may be related to the rotational output (e.g., angular velocity, torque, etc.) relative to a given driving force.

[0041] Each bearing in the bearing assembly includes an interface 320 in which a working fluid (e.g., a liquid metal such as gallium indium tin liquid) acts as a lubricant and supports the load. The thickness of the interface 320 can be selected based on factors such as the type of liquid metal or other working fluid used in the bearing, the manufacturing tolerances of the components, and the expected system operating temperature. Thus, in one or more use case examples, the liquid metal interface 320 can be on the order of 5 micrometers (μm) to 40 μm. In one or more examples, the liquid metal used as the working fluid in the bearing assembly can include gallium, tin, indium, combinations thereof, etc. However, other working fluids besides liquid metals are also contemplated, such as grease, oil, combinations thereof, etc.

[0042] In the illustrated embodiment, the X-ray source target 310 is coupled (e.g., rotationally coupled) to the sleeve 306. However, alternative embodiments of the above-described X-ray source target 310 coupled to a rotating shaft assembly are contemplated. The X-ray source target 310 includes a focal spot 322, which serves as a surface for receiving an electron beam from the cathode 324 during operation of the X-ray source 300.

[0043] Cathode 324 can be controlled by a controller (such as...) Figure 2 The X-ray controller 210 shown receives signals to generate an electron beam oriented toward the surface of the X-ray source target 310. When the electron beam from the cathode 324 strikes the focal point 322 of the X-ray source target 310, an X-ray beam 326 is generated. The X-rays are emitted through an X-ray window 328 (e.g., an opening) in the housing 302.

[0044] The X-ray source 300 also includes a rotor 330 and a stator 332. In the illustrated embodiment, the rotor 330 is coupled to the sleeve 306 and is designed to apply rotational motion thereto. However, in the above-described embodiment where the shaft rotates, the rotor may be coupled to the shaft. The stator 332 is shown positioned outside the low-pressure package 304 (e.g., outside the housing 302). However, other suitable stator locations are contemplated. Typically, the rotor and stator may include windings, magnets, electrical connections, etc., which electromagnetically interact in response to, for example, [missing information - likely a specific energy source]. Figure 2 The X-ray controller 210 shown receives control commands and generates rotor rotation.

[0045] Figure 4 Another example of a hydrodynamic bearing system 400 is shown. It should be understood that... Figure 4 The bearing system 400 shown may be included in the above reference. Figures 1 to 3In the aforementioned X-ray source, the hydrodynamic bearing system 400 includes a shaft 402 and a sleeve 404. An X-ray source target 406 is shown attached to the sleeve 404. Therefore, during system use, the sleeve 404 rotates while the shaft 402 remains relatively stationary. However, as previously mentioned, embodiments in which the sleeve remains stationary while the shaft rotates are contemplated.

[0046] The hydrodynamic bearing system 400 includes a plurality of bearings. Each bearing includes a fluid interface 408 (e.g., a liquid metal interface) between a segment of shaft 402 and sleeve 404. It should be understood that the fluid interface extends circumferentially around shaft 402. In the illustrated embodiment, the bearings include a first journal bearing 410, a second journal bearing 412, a first thrust bearing 414, and a second thrust bearing 415. However, other bearing arrangements for the system are contemplated, such as arrangements with different numbers of journal bearings and / or thrust bearings. The journal bearings support radial loads, and the thrust bearings support axial loads.

[0047] Shaft 402 is shown having a herringbone groove 416 associated with a first journal bearing 410 and a second journal bearing 412. Sleeve 404 may also include grooves (e.g., helical grooves), schematically shown at 418. These grooves (e.g., herringbone and helical grooves) can work together to generate pressure in the working fluid (e.g., liquid metal) to support the bearing load. Supporting the bearing load prevents rotating parts from contacting stationary parts. Therefore, it should be understood that the bearings described herein can be self-acting bearings designed to generate pressure using the surface geometry at the bearing interface. Different geometries and arrangements of the grooves and the corresponding flow dynamics are further described below.

[0048] The first thrust bearing 414 and the second thrust bearing 415 include flanges 420 extending radially from the body 422 of the shaft 402 toward complementary segments 424 in the sleeve body. The first thrust bearing 414 and the second thrust bearing 415 may be located on opposite axial sides of the flanges 420. The bearing system 400 may also include a reservoir 426 positioned between the first journal bearing 410 and the second journal bearing 412. The reservoir 426 may be formed with an annular groove to maintain an additional volume of working fluid (e.g., liquid metal) in the bearing when needed.

[0049] The hydrodynamic bearing system 400 may also include one or more seals designed to reduce the amount of fluid leaking from the bearing. The seals may be rotary labyrinth seals, which provide a circuitous path to prevent the molten metal from flowing axially. However, other or alternative types of suitable seals or combinations of seals are contemplated, such as capillary seals, hydrodynamic seals, flange seals, foil seals, etc. For example, a first seal 428 is shown positioned axially outward from the first journal bearing 410 to reduce (e.g., prevent) lubricant flow through the first seal 428 in a direction generally indicated by arrow 429. Similarly, a second seal 430 is shown positioned axially outward from the thrust bearing 414 to reduce (e.g., prevent) lubricant flow through the second seal 430 in a direction generally indicated by arrow 432. However, other seal configurations are possible without departing from the scope of this disclosure.

[0050] Depending on the resulting heat distribution and the material properties of the bearing components (e.g., shafts, sleeves, and liquid metal lubricants) as well as the load applied to the bearing, hydrodynamic bearings may experience thermal and structural deformation during operation (e.g., rotation of rotating components such as sleeves).

[0051] For example, go to Figure 5 An exemplary thermal and structural deformation mode 550 of a hydrodynamic bearing 500 is shown, the bearing including a sleeve 504 circumferentially surrounding a shaft 502 with a gap 508 between them. The hydrodynamic bearing 500 can be modified according to the thermal and structural deformation mode 550 to produce a modified hydrodynamic bearing according to this disclosure, such as by performing the methods disclosed herein.

[0052] In the figure, the sleeve 504 is shown as a cross-section so that the shaft 502 can be seen. The sleeve 504 and the shaft 502 extend between a first end 552 and a second end 554, wherein the second end 554 is axially opposite the shaft 502 and its components and / or features, or components and / or features coupled thereto, to the first end 552. A rotation axis 350 extends centrally through the shaft 502 and the sleeve 504, such that under low load conditions (e.g., when such loads are applied as...), the shaft 502 is positioned such that... Figure 1 When the frame 102 is stationary, the shaft 502 and the sleeve 504 are concentric with each other. Under high load (e.g., when the frame is rotating), the axis of rotation 350 extending through the center of the shaft 502 can be slightly displaced or offset from the center of the sleeve 504, causing the shaft 502 and the sleeve 504 to be eccentric.

[0053] Shaft 502 may include flange 532, which is similar to Figure 4 The flange is 420. For clarity, Figures 5 to 7 , Figure 9 and Figures 11 to 15 The shaft 502 has been simplified herein; however, it should be understood that the shaft 502 and / or sleeve 504 may also include other features described herein, such as Figure 4 The storage device 426. In addition, the shaft 502 and the sleeve 504 may include one or more journal bearings and / or thrust bearings, as described above.

[0054] The outer diameter 512 of the outer surface 518 of shaft 502 can be axially constant under non-operating conditions (e.g., when in a rotating stationary state) (e.g., the same value measured at any axial position). Similarly, the inner diameter 514 of the inner surface 522 of sleeve 504 can be axially constant under non-operating conditions. Therefore, the outer surface 518 and inner surface 522 can be cylindrical under non-operating conditions. Furthermore, the radial thickness 520 of the gap 508 through which lubricant fluid flows can be axially constant under non-operating conditions.

[0055] Stationary components (e.g., shaft 502) may include grooves 506 (e.g., on outer surface 518) that resemble... Figure 4 The groove 416 can be configured to generate pressure in the gap 508 where a lubricant fluid (e.g., liquid metal) is disposed. The groove 506 can be arranged in a herringbone pattern or other configuration as shown. For example, alternative groove patterns may include wavy or spiral grooves. Grooves may be additionally or alternatively formed in rotating components (e.g., sleeve 504). The grooves in the rotating and stationary components can be arranged in different patterns.

[0056] The shaded area 510 indicates the expected thermal and structural deformation mode 550 experienced by the sleeve 504 according to the heat distribution generated by the operation of the hydrodynamic bearing 500 (e.g., the relative rotational motion of the shaft 502 and the sleeve 504). That is, the shaded area 510 may include material of the sleeve 504 before operation (e.g., rotation) and may include negative space during operation. More specifically, in Figure 5 In the exemplary thermal and structural deformation mode 550 shown, the sleeve 504 changes under operating conditions such that, due to the heat distribution generated during operation, the cylindrical inner surface 522 of the sleeve 504 with a constant axial inner diameter 514 transforms under operating conditions into a tapered inner surface 524 with a variable axial inner diameter 516. More generally, the shape of the sleeve 504 changes due to thermal and structural deformation, causing its inner diameter to change axially. Figure 7 and Figure 8 An example of a modification to the depth of groove 506 is provided to counteract the effects of thermal and structural deformation modes 550 on the forces applied to the lubricant fluid disposed in gap 508, which could lead to insufficient lubrication.

[0057] As more heat can accumulate near flange 532, the intensity of thermal and structural deformation increases toward the second end 554. However, the thermal and structural deformation modes can vary for other shaft and / or sleeve geometries and operating conditions. Furthermore, different heat distributions are possible for the same bearing under different operating conditions (e.g., rotational speed, load, location within the system, etc.) or when included in different systems. For example, under thermal and structural deformation, the inner diameter of sleeve 504 can exhibit a non-linear profile axial fluctuation, rather than... Figure 5 The linear profile shown can be either linear or nonlinear, and may be axially asymmetric. That is, the thermal and structural deformation mode 550 may be asymmetric about the xz plane at the axial midpoint of the axial length 540 of the sleeve 504. In this way, lubricant fluid can be pumped axially out of the bearing.

[0058] For example, go to Figure 6 This illustrates another anticipated thermal and structural deformation mode 650 for the hydrodynamic bearing 500. Thermal and structural deformation modes 650 and 550 can differ due to varying system configurations and / or operating conditions, such as the rotational speed of sleeve 504, torque load, and differences in mass or geometry of the components coupled to shaft 502 and sleeve 504. However, similar to thermal and structural deformation mode 550, thermal and structural deformation mode 650 can be asymmetric about the plane at the axial midpoint of the axial length 540. The hydrodynamic bearing 500 can be modified according to thermal and structural deformation mode 650 to produce a modified hydrodynamic bearing according to this disclosure, such as by performing the methods disclosed herein.

[0059] The shaded area 610 indicates the thermal and structural deformation mode 650 experienced by the sleeve 504 according to the heat distribution generated by the operation of the hydrodynamic bearing 500 (e.g., the relative rotational motion of the shaft 502 and the sleeve 504). That is, the shaded area 610 may include material of the sleeve 504 before operation (e.g., rotation) and may include negative space during operation. More specifically, in Figure 6 In the exemplary thermal and structural deformation mode 650 shown, the sleeve 504 is altered such that the cylindrical inner surface 522 of the sleeve 504, which originally had a constant axial inner diameter 514, transforms under operating conditions into a curved inner surface 624 with a variable axial inner diameter 616 due to heat distribution during operation. More generally, similar to... Figure 5 As shown, the shape of sleeve 504 changes due to thermal and structural deformation, causing its inner diameter to change axially. However, the profile of the thermal and structural deformation mode 650 differs from that of the sleeve. Figure 5 The thermal and structural deformation mode 550 may be caused by the different operating conditions (e.g., rotational speed, load, etc.) under which the bearing 500 is expected to operate.

[0060] Therefore, sleeve 504 can be thermally deformed in various ways depending on its geometry and operating conditions. Additionally or alternatively, shaft 502 can be thermally deformed. That is, in other examples, only shaft 502 or both shaft 502 and sleeve 504 may undergo thermal and structural deformation. In any configuration where bearing 500 undergoes thermal and structural deformation, the geometry of clearance 508 can change. Structural deflection due to loads on bearing 500 can also cause the geometry of clearance 508 to change during rotation. For example, such thermal and structural deformation experienced by one or both of shaft 502 and sleeve 504 can cause changes in the radial dimensions and / or shape of clearance 508, resulting in an unintended flow pattern of the lubricant fluid (e.g., liquid metal) therein. Specifically, groove 506 can be arranged during manufacturing to guide fluid through clearance 508 with a desired flow pattern. However, when the geometry of clearance 508 changes due to thermal and structural deformation during operation, an unintended fluid pattern different from the desired flow pattern may occur. In some examples, unintended flow patterns may cause lubricant fluid to be pumped out of bearing 500, resulting in insufficient wear, damping and stiffness characteristics and / or other consequences caused by insufficient lubricant.

[0061] The hydrodynamic bearing of this disclosure can be modified based on anticipated thermal and structural deformation profiles to counteract the effects of thermal and structural deformation on lubricant flow, thereby retaining more (e.g., all) of the lubricant within the bearing. More specifically, the characteristics of the hydrodynamic bearing of this disclosure can depend on the anticipated thermal and structural deformation profiles of conventional bearings under anticipated operating conditions within a system such as an imaging system. For example, references are made below. Figure 16 The method further describes how the anticipated thermal and structural deformation profiles can be determined through predictive modeling and / or empirical testing of unmodified (e.g., conventional) bearings, and used to determine appropriate modifications to the sleeve and / or shaft. Therefore, Figure 5 and Figure 6 The thermal and structural deformation modes shown serve as non-limiting examples of expected thermal and structural deformation profiles for illustrative purposes. Figure 5 and Figure 6 Thermal and structural deformation profiles and reference Figures 7 to 10 The relationship between the corresponding hydrodynamic bearing examples according to this disclosure is described. Since the expected thermal and structural deformation modes can be axially asymmetric, as will be further described below, modifications can be axially asymmetric to counteract the axial pumping effect of the thermal and structural deformation modes. Figures 11 to 15 Additional examples of hydrodynamic bearings according to this disclosure are shown, which may correspond to different thermal and structural deformation modes.

[0062] Go to Figure 7 and Figure 8 , Figure 7An example of a bearing 700 is illustrated, having a groove depth 704 that varies axially according to thermal and structural deformation modes. Figure 8 The graph 800 shows the groove depth 704. The groove depth 704 can be the radial distance from which the groove 506 is recessed from the outer surface 518. Figure 7 The view 750 shown can be a yz cross section coplanar with the axis of rotation 350.

[0063] View 750 shows sleeve 504 and shaft 702, which is compared to Figure 5 and Figure 6 Shaft 502 in the middle has been modified according to thermal and structural deformation mode 550. Specifically, Figure 7 and Figure 8 The groove depth 704 pattern shown corresponds to the thermal and structural deformation mode 550. In this way, Figure 7 The bearing 700 shown may be a modified bearing according to this disclosure, wherein the modification is selected based on the anticipated thermal and structural deformation mode 550. Therefore, operating the bearing 700 under operating conditions that cause the bearing 500 to exhibit the thermal and structural deformation mode 550 may result in reduced fluid losses compared to operating the bearing 500 under the same operating conditions.

[0064] The curve 800 includes groove depths 704 and thermal and structural deformation modes 550, respectively represented by first trace 802 and second trace 804. The axial position may increase to the right along the horizontal axis 806 (e.g., from the first end 552 to the second end 554), and the radial position may increase upwards along the vertical axis 808 (e.g., radially outwards from axis 350). A first reference trace 812 shows the radial profile of the outer surface 518 of the shaft 502 under non-operating conditions. Therefore, when trace 802 is at reference trace 812, the groove depth can be zero, and trace 802 may not extend above reference trace 812. A second reference trace 814 shows the radial profile of the inner surface 522 of the sleeve 504 under non-operating conditions (e.g., without thermal deformation). The space between the first reference trace 812 and the second reference trace 814 represents the radially inserted gap 508 between the sleeve 504 and the shaft 702. Therefore, the first reference trace 812 and the second reference trace 814 are spaced apart from each other by a distance equal to the radial thickness 520.

[0065] Although the trench depth 704 is a discrete measurement, the first trace 802 is shown as continuous to represent all combinations of trenches independent of the trench arrangement (e.g., herringbone, spiral, number of trenches, trench spacing, etc.). That is, depending on the arrangement of the trenches 506, the point representing the trench depth can fall anywhere along the trace 802. For example, if the trench width 706 and / or the distance 708 between axially adjacent trenches 506 are... Figure 7 The different patterns shown in the diagram allow for adjustment of the groove depth 704, ensuring that the groove depth maintains the profile shown by the trace 802, in order to mitigate the effects of thermal and structural deformation modes 550 in a similar manner. The groove depth 704 can be circumferentially (e.g., radially) constant, such that for a given axial point along the horizontal axis 806, the groove depth 704 represents the groove depth at any circumferential location on the axis 702.

[0066] As shown in view 750 and graph 800, the depth 704 of the groove 506 varies axially. That is, trace 802 is not a horizontal line parallel to the horizontal axis 806. Therefore, the depth of the groove 506 in the modified shaft 702 differs from that of the shaft 502. Furthermore, the groove depth profile indicated by trace 802 is a mirror image of the thermal and structural deformation profile indicated by trace 804, with a third reference trace 816 equidistantly located between the first reference trace 812 and the second reference trace 814 as the boundary. In this way, the groove depth and the magnitude of thermal deformation can be proportional. Therefore, the groove depth 704 is axially asymmetric. Although shown as linear, reference traces 812, 814 can be non-linear, for example, in cases where the shaft and / or sleeve described below is modified to have axially varying dimensions (e.g., diameter). Furthermore, curve 800 represents the bearing under non-operating conditions (e.g., when the rotating component is stationary), and when under operating conditions, it may experience eccentricity, such that reference traces 812, 814 are separated by a distance different from the radial thickness 520.

[0067] Figure 9 and Figure 10 Another example of bearing 900 is shown (where groove depth 704 varies axially according to thermal and structural deformation modes) and a graph 1000 of groove depth 704 are also shown. Specifically, Figure 9 and Figure 10 The groove depth 704 pattern shown can correspond to Figure 6 Thermal and structural deformation modes 650. Figure 9 The view 950 shown can be a yz cross section coplanar with the axis of rotation 350.

[0068] View 950 shows sleeve 504 and shaft 902, with Figure 5 and Figure 6 Compared to shaft 502, this shaft has been modified according to thermal and structural deformation mode 650. Specifically, Figure 9 and Figure 10The groove depth 704 pattern shown corresponds to thermal and structural deformation mode 650. In this way, bearing 900 can be a modified bearing according to this disclosure, wherein the modification is selected according to the intended thermal and structural deformation mode 650. Therefore, operating bearing 900 under operating conditions that generate thermal and structural deformation mode 650 on bearing 500 can result in reduced fluid loss compared to operating bearing 500 under the same operating conditions.

[0069] Despite the fact that the trench 506 is Figure 7 and Figure 9 The groove 506 is shown as having a rectangular profile, but in other examples, it may have other cross-sectional shapes. For example, the groove 506 may have a circular profile instead of right-angled corners. Furthermore, different ratios of width 706 to distance 708 are also possible. Additionally, the width 706 may be adjusted, in addition to or as an alternative to depth 704, to counteract the thermal and structural deformation effects on lubricant flow.

[0070] The curve 1000 includes a groove depth 704, represented as a first trace 1002 and a second trace 1004, and thermal and structural deformation modes 650, respectively. Similar to... Figure 8 The first trace is 802. Figure 10 The first trace 1002 is shown as a continuous line to represent the trench depth of any trench arrangement (e.g., number, spacing, width, etc.).

[0071] As shown in view 950 and graph 1000, the depth 704 of the trench 506 varies axially. Furthermore, the trench depth profile indicated by trace 1002 is a mirror image of the thermal and structural deformation profile indicated by trace 1004 about a third reference trace 816. Additionally, the trench depth profile is axially asymmetric, which can cause a reaction to the axial pumping of lubricant fluid (e.g., liquid metal) applied by thermal and structural deformation.

[0072] For a given thermal and structural deformation profile, there may be more than one possible corresponding groove depth profile. That is, the groove depth profile may not be a mirror image of the expected thermal and structural deformation profile.

[0073] Go to Figure 17For comparative purposes, another example of the expected thermal and structural deformation profile of graph 1700 is shown as a profile with a corresponding groove depth. The unmodified (e.g., axially constant) groove depth is represented by reference line 1708. The expected thermal and structural deformation profile is represented by a first trace 1702. The first and second groove profiles are shown as a second trace 1704 and a third trace 1706, respectively. As described above and indicated by the second trace 1704, the grooves can be made deeper in deformed regions with more significant thermal and structural deformation (e.g., deformed region 1722). In such examples, the grooves can remain unmodified in undeformed regions without expected thermal or structural deformation (e.g., first undeformed region 1724 and second undeformed region 1726). Alternatively, as indicated by the third trace 1706, the grooves in regions experiencing thermal and structural deformation (e.g., deformed region 1722) can be made shallower, thereby reducing the pumping intensity in that region. In this way, the undeformed region can balance the impact on lubricant pumping caused by the deformed region. In some examples, the undeformed region can dominate pumping characteristics such that the change in the pressure contribution of the deformed region to lubricant pumping from an undeformed state (e.g., when stationary) to a state of thermal and structural deformation (e.g., during rotation) is negligible (e.g., 5% or less). In addition to reducing the trench depth at the deformed region, the trenches at the undeformed region can be made deeper to further ensure that the undeformed region dominates pumping characteristics.

[0074] Therefore, based on the expected thermal and structural deformation modes of an unmodified bearing under a set of operating conditions, the groove depth can be modified to vary axially according to the thermal and structural deformation profile to produce the hydrodynamic bearing of this disclosure, in which lubricant fluid is unlikely to leak from it. References below... Figures 11 to 15 Other modifications for producing the hydrodynamic bearings according to this disclosure are described.

[0075] Go to Figure 11 The image shows shaft 1102. Shaft 1102 includes grooves 506 arranged in a herringbone pattern, which can be conceptually divided into multiple segments. These segments include a first segment 1112, a second segment 1114, a third segment 1116, and a fourth segment 1118, defined by vertical dashed lines 1142 between them. Figure 11 The segments of the herringbone groove pattern shown can be divided into linear and parallel regions according to the segmentation of groove 506. In this way, the segment boundaries (e.g., at the vertical dashed line 1142) can extend through the apex of the herringbone groove. In other examples where the grooves are not arranged in a herringbone pattern, the segments can be divided according to other features of the groove pattern. For example, segment boundaries can be set at the inflection points of curved (e.g., sinusoidal) grooves.

[0076] The first segment 1112, the second segment 1114, the third segment 1116, and the fourth segment 1118 have a first axial length of 1122, a second axial length of 1124, a third axial length of 1126, and a fourth axial length of 1128, respectively. In some examples, segments 1112, 1114, 1116, and 1118 may all be approximately the same length. That is, lengths 1122, 1124, 1126, and 1128 may all be approximately equal. Alternatively, lengths 1122, 1124, 1126, and 1128 may be different from each other. For example, the first axial length 1122 may be longer or shorter than one or more of the second axial length 1124, the third axial length 1126, and the fourth axial length 1128. For example, the second axial length 1124 may be greater than the first axial length 1122, while the third axial length 1126 and the fourth axial length 1128 may be approximately equal to each other. For example, the fourth axial length 1128 can be greater than the third axial length 1126, while the first axial length 1122 and the second axial length 1124 can be approximately equal to each other. For example, the sum of the first axial length 1122 and the third axial length 1126 can be greater than or less than the sum of the second axial length 1124 and the fourth axial length 1128.

[0077] Lengths 1122, 1124, 1126, 1128, their ratios and / or the ratio of their sums, etc., can be determined based on the expected thermal and structural deformation modes (e.g., Figure 5 and Figure 6The respective thermal and structural deformation modes (550 or 650) and / or the pressure generated at the liquid metal interface are selected. For example, a segment expected to undergo a greater degree of thermal and structural deformation can be made relatively longer than a segment expected to undergo relatively less thermal and structural deformation (or none at all) to offset the effect of thermal and structural deformation on pumping strength. Lengthening a segment increases its pumping strength. Shortening a segment decreases its pumping strength. For example, if the amount of thermal and structural deformation in the second segment 1114 is expected to be greater than that in the first segment 1112, the pumping effect of the second segment 1114 may be weaker compared to the first segment 1112 due to the wider gap. Therefore, the second axial length 1124 can be made relatively longer than the first axial length 1122 by shortening the first axial length 1122 and / or extending the second axial length 1124. In this way, the pumping effects of the first segment 1112 and the second segment 1114 can be more equal under operating conditions (e.g., under thermal deformation and structural loading). Similar to groove depth, the segment lengths of segments not expected to experience the effects of thermal and structural deformation modes can be adjusted to counteract these effects. For example, if the bearing is expected to experience thermal and structural deformation that increases pumping intensity in the second segment 1114 while remaining constant in other segments, the second segment 1114 can be made shorter, and / or the other segments can be made longer to offset the effects of thermal and structural deformation on fluid flow.

[0078] Since the thermal and structural deformation modes can be axially asymmetric (e.g., planar asymmetry about the midpoint of the axis), the corresponding modified segment lengths can also be axially asymmetric. For example, the first axial length 1122 and the fourth axial length 1128 can be unequal to each other, and the second axial length 1124 and the third axial length 1126 can be unequal to each other. In this way, axial pumping can be designed to occur in an axial direction opposite to the expected thermal and structural deformation modes, thereby preventing fluid from being pumped out of the bearing under operating conditions.

[0079] In addition to changing the segment length, or as an alternative, the groove angle 1140 of groove 506 can be modified to vary axially. The groove angle 1140 can be an acute angle formed by a reference groove and an axis parallel to the axis of rotation 350. For example, the groove angle 1140 can vary by segment. More specifically, the groove angle 1140 can be modified in regions where greater thermal and structural deformation is expected to occur, in order to increase the pressure in such regions. Additionally or alternatively, the groove angle 1140 can be modified in regions where less thermal and structural deformation is expected (including zero), in order to decrease the pressure in such regions. The relationship between the groove angle and pressure can be non-monotonic. That is, depending on the initial (e.g., unmodified) groove angle, the groove pattern (e.g., segment length), the thermal and structural deformation mode, etc., increasing the groove angle may increase pressure in some examples and decrease pressure in others.

[0080] These segments can have different groove depths, resulting in stepped or other discontinuous groove depth profiles, different from the reference. Figures 7 to 10 The description describes the continuous trench depth profile. In this way, in some examples, trench segments within each segment may have the same depth, but trench segments in different segments may have different depths. The segment trench depth can vary in addition to or as an alternative to segment length. For example, in an example where the trench depth is axially constant, the segment lengths may be non-uniform. In an example where the trench depth differs in each segment, the segment lengths may be equal. As an alternative example, each segment may have a different length and trench depth than one or more segments in other segments.

[0081] For illustrative purposes, turn to Figure 12 A graph 1200 is shown with a groove depth profile indicated by trace 1202, wherein different groove segments have different depths. Trace 1202 is discontinuous at the vertical dashed line 1142 indicating the segment boundaries, causing the groove depth to change abruptly at the segment transitions, rather than as... Figures 7 to 10 The example shows a continuous variation. Other combinations of segment-to-groove depths are also possible depending on the corresponding expected thermal and structural deformation modes. Furthermore, although... Figure 11 and Figure 12 The example illustrates four segments, but in other examples, there may be more or fewer than four segments depending on the groove arrangement, shaft dimensions (e.g., diameter and axial length), etc.

[0082] In addition, return Figure 7The groove-to-groove ratio, which is equal to the ratio of the axial distance 708 between the grooves 506 to the groove width 706, can vary axially according to the expected thermal and structural deformation mode (such as the thermal and structural deformation mode 550 shown therein). For example, in regions where relatively larger thermal and structural deformation is expected, such as at the second end 554 in thermal and structural deformation mode 550, the groove width 706 can be made larger and / or the axial distance 708 can be made shorter. Additionally or alternatively, in regions where relatively smaller thermal and structural deformation is expected, the groove width 706 can be made smaller and / or the axial distance 708 can be made longer. Similar to the groove depth 704, the groove width 706 and the axial distance 708 can have continuous or discrete (e.g., segment-based) profiles.

[0083] Furthermore, in some examples, the cross-sectional shape of groove 506 can be modified to vary axially according to the expected thermal and structural deformation modes. For example, the corners of groove 506 can be rounded with varying corner radii to affect the pressure on the lubricant fluid in gap 508, thereby counteracting the effects of thermal and structural deformation. The corners at the open ends and / or closed ends of groove 506 can be modified (e.g., rounded). Thus, the cross-sectional shape can be a rectangle with sharp (e.g., 90-degree) corners, a rectangle with curved corners, or any other shape that affects the pressure on the lubricant fluid in a way that counteracts thermal and structural deformation modes, as shown. For example, groove 506 can be modified to taper radially inward, thereby forming a trapezoidal or triangular cross-sectional shape. The cross-sectional shape can be different for each groove in the groove. Alternatively, the cross-sectional shape can be the same for grooves within the same segment.

[0084] Furthermore, in some examples, one or more segments can be modified to be without grooves in order to counteract the expected thermal and structural deformation modes. For example, go to Figure 13 The diagram shows a shaft 1302 comprising segments without grooves. Shaft 1302 includes a first segment 1112, a second segment 1114, a third segment 1116, and a fourth segment 1118, defined by a vertical dashed line 1142 between them. One or more of lengths 1122, 1124, 1126, and 1128 may be... Figure 11 The difference shown is due to the addition of grooveless segments, such as fifth segment 1304 and sixth segment 1306, which have a fifth length 1308 and a sixth length 1310, respectively, and these segments are defined by vertical dashed lines 1142. Thus, segments of a grooved pattern can be defined by features of the groove (e.g., the vertices of the herringbone pattern) and / or the absence of the groove.

[0085] The groove depth of the fifth segment 1304 and the sixth segment 1306 can be zero, making the surfaces of the fifth segment 1304 and the sixth segment 1306 groove-free (e.g., smooth). For example, shaft 1102 can be modified to shaft 1302 by filling the grooves to form a smooth surface. Alternatively, shaft 1102 can be machined in certain areas to flatten the grooves by removing material between them, thereby eliminating the grooves in those areas. Filling the grooves may result in a relatively larger circumferential average diameter of the groove-free segments 1304, 1306 compared to removing material between them. Therefore, the diameter of the groove-free segments can be considered when selecting a method for removing the grooves. Again, a new shaft (e.g., constructed from a blank, rather than modifying shaft 1102) can be manufactured with the same characteristics as shaft 1102 except for segments 1304 and 1306.

[0086] In addition to or as alternatives to the modifications described herein, removing the grooves from one or more segments can counteract the expected thermal and structural deformation modes. For example, the groove pattern can be as follows: Figure 13 The arrangement shown (e.g., the trench is discontinuous due to the absence of trench segments) and the trench can be modified to vary continuously or along the axial direction of the segments. That is, except in the axial region including the absence of trench segments, the trench depth can follow a pattern such as... Figures 7 to 10 The continuous profile shown, or each segment may have a segment-specific groove depth that is different from one or more other segments (e.g., approximately the same groove depth throughout a given segment).

[0087] Go to Figure 14 Another possible modification to the shaft of the hydrodynamic bearing according to this disclosure is an axial change in its outer diameter. For example, Figure 14 The diagram illustrates shaft 1402, where the outer diameter 512 is modified to vary axially along a portion of shaft 1402. The difference between the outer diameter 512 and the minimum diameter 1408 of the axially varied outer diameter 1410 can be proportional to the profile of the expected thermal and structural deformation mode. Furthermore, the axial length 1406 of shaft 1402 affected by the outer diameter 512 modification (which can extend up to the entire axial length of shaft 1402) can be selected based on the expected thermal and structural deformation mode. Additionally, the profile of the axially varied outer diameter 1410 can reflect the expected thermal and structural deformation mode. For example, the smaller the axially varied outer diameter 1410 at a given axial location, the less significant the expected effect on the modified pressure at that axial location due to thermal and structural deformation of the shaft and / or sleeve. The dashed boundary 1404 indicates the unmodified shaft (e.g., [missing information]) used to predict the expected thermal and structural deformation mode. Figure 5 and Figure 6 The axial outer diameter of the shaft 502 is constant.

[0088] It should be understood that, although shown separately herein for clarity, modifications to the shafts described above may also be combined. For example, the shaft of a hydrodynamic bearing according to this disclosure may include one or more of the modifications described herein, including such modifications. Figures 7 to 10 and Figure 12 The axially varying groove depth is shown, such as Figure 11 The varying axial segment lengths shown are as follows: Figure 13 The grooveless segment shown, and as... Figure 14 The diameter varies axially. In such examples combining two or more modifications, the intensity of the modifications can be reduced to achieve synergistic effects rather than overcorrecting the thermal degradation pattern. For example, the axis of both a groove depth varying axially and a segment length varying axially may include a groove depth profile that mimics the thermal and structural deformation profile, but is not a mirror image as illustrated in the examples herein. As a more specific example, refer to... Figure 7 and Figure 8 In examples where axially varying groove depths are combined with another shaft modification (e.g., when segment lengths are unequal and / or the shaft diameter varies axially), the first trace 802, illustrating the groove depth 704 profile, may have a slope closer to zero than the second trace 804, illustrating the thermal and structural deformation mode 550. Such a combination may be helpful in addressing thermal and structural deformation profiles, which may require grooves with depths exceeding their possible range due to the relative size of the shaft diameter. Additionally or alternatively, combined shaft modifications may be advantageous when addressing more complex thermal and structural deformation profiles where modifying the groove depth alone cannot fully mitigate their effects. Similar reasoning can be applied to other combinations of shaft modifications. For example, if the minimum diameter may be too small when the outer diameter is axially varied alone according to the intensity of thermal and structural deformation (e.g., due to material constraints), another modification can be combined with an axial variation of the outer diameter to effectively increase the minimum diameter.

[0089] In addition to the above references Figures 7 to 14 In addition to or as an alternative to the one or more shaft modifications described, the sleeve of the hydrodynamic bearing may be modified to counteract thermal and structural deformation.

[0090] For an example of sleeve modification, refer now. Figure 15 The diagram illustrates a hydrodynamic bearing 1500 according to the present disclosure, which includes a shaft 502 and a sleeve 1504. The dashed boundary 1510 indicates an unmodified sleeve having an axially constant inner diameter 514 (e.g., Figure 5 and Figure 6 The shape of the sleeve 504.

[0091] Compared to sleeve 504, sleeve 1504 is modified such that its inner diameter 1506 varies axially under non-operating conditions. Therefore, the radial dimension 1508 of clearance 508 varies axially under non-operating conditions. In this way, the inner surface 1512 of sleeve 1502 is not cylindrical. The inner diameter 1506 can be larger in axial regions where expected thermal and structural deformation is less significant. Therefore, the greater the magnitude of expected thermal and structural deformation at axial locations, the smaller the difference between the unmodified inner diameter (e.g., diameter 514) and the axially varied inner diameter 1506. The profile of the inner diameter 1506 is shown as linear and thus corresponds to thermal and structural deformation modes with linear profiles, such as... Figure 5 The thermal and structural deformation mode 550 is described; however, the inner diameter 1506 can be adjusted according to the expected thermal and structural deformation mode and / or whether it is combined with shaft modifications such as those described above, including nonlinear diameter profiles of the bending profile. For example, if both the groove depth of the groove 506 and the inner diameter 1506 are axially varied, the magnitude of each modification can be reduced. In detail, in such an example, the profiles of the groove depth and the inner diameter can have a reduced slope compared to the expected linear thermal and structural deformation mode. Other combinations of shaft and / or sleeve modifications can be similarly applied to achieve the effect of counteracting the influence on lubricant flow during thermal deformation under operating conditions.

[0092] Go to Figure 16 A flowchart of a method 1600 for manufacturing a hydrodynamic bearing according to this disclosure is shown. It should be understood that method 1600 can be performed to manufacture any stationary and rotating components (e.g., shafts and sleeves) in a bearing system, as referenced above. Figures 1 to 15 As described. Furthermore, method 1600 can be executed via one or more manufacturing devices including a controller and memory. Thus, the manufacturing devices can implement method 1600 in response to, for example, programming commands and / or user commands.

[0093] Method 1600 begins at 1602, where the expected thermal and structural deformation modes are determined (e.g., Figure 5 and Figure 6 Each of the respective thermal and structural deformation modes 550 or 650), wherein the expected thermal and structural deformation mode is in the bearing (e.g., Figure 5 and Figure 6 The bearing 500) is expected to undergo geometric changes during operation. The bearing includes a sleeve, a shaft, and grooves arranged in a groove pattern (on the sleeve and / or shaft), wherein the inner diameter of the sleeve (e.g., Figure 5 and Figure 6 The constant inner diameter 514), the outer diameter of the shaft (e.g., Figure 5 and Figure 6The constant outer diameter (512), groove cross-sectional shape, groove ratio, groove angle, and groove depth are axially constant. In at least some examples, the shaft is a stationary component and the sleeve is a rotating component, but in other examples the opposite may be true. Grooves may be formed in either the sleeve or the shaft. Expected thermal and structural deformation modes can be calculated using predictive modeling and / or via empirical testing using an X-ray source, where a hydrodynamic bearing with a constant sleeve inner diameter, constant shaft outer diameter, constant groove cross-sectional shape, constant groove ratio, constant groove angle, and constant shaft groove depth (e.g., Figure 5 and Figure 6 The bearing 500). Thermal and structural deformation modes (e.g., Figure 5 or Figure 6 Each thermal and structural deformation mode (550 or 650) may be influenced by material properties and the heat distribution generated during operation. Therefore, the thermal and structural deformation modes may depend on one or more of the following: groove geometry (e.g., herringbone pattern, depth, cross-sectional shape, etc.), relative dimensions, material, etc. In addition to the physical aspects of the bearing design, the thermal and structural deformation modes may also depend on the rotational motion of rotating components (e.g., sleeves) during operation. Therefore, for a given bearing, there may be more than one potential thermal and structural deformation mode, each corresponding to expected operating conditions such as rotational speed, torque load, etc. Therefore, predictive modeling and / or empirical verification techniques can be adapted to account for the effects of rotational metrics (e.g., angular velocity, torque, etc.) and configurations within the system (e.g., X-ray sources in an imaging system), such as orientation within the system, other components of the system, etc.

[0094] Method 1600 proceeds to 1604, wherein the shaft is modified according to thermal and structural deformation modes. In one example, the modification can be manufactured using laser processing. In such an example, the laser dwell time and number of passes can be used to control modifications such as the profile (e.g., position, depth, etc.) of the outer surface of the shaft, the inner surface of the sleeve, and / or the grooves. However, in other examples, electrochemical machining, grinding (e.g., grinding of circular protrusions), and / or sanding can be used to manufacture the modification. Other methods of processing the modifications described herein are also possible without departing from the scope of this disclosure. Furthermore, in some examples, modifying the bearing may include (e.g., from raw materials) manufacturing a new shaft and / or sleeve with the desired modification (e.g., the difference relative to the unmodified bearing used at 1602 to determine the expected thermal and structural deformation modes), rather than directly adjusting (e.g., machining) the bearing parts used at 1602. Thus, as used herein, modifications may include laser processing, electrochemical machining, grinding, sanding, and / or modification. In at least some of the examples described above, the modification may be axially asymmetrical (e.g., asymmetrical relative to the axial midpoint of the bearing) in order to counteract the axial lubricant pumping effect of the expected thermal and structural deformation modes.

[0095] In at least some examples, 1604 includes 1606, wherein one or more of the sleeve inner diameter, shaft outer diameter, groove cross-sectional shape, and groove depth are modified to vary axially according to the determined thermal and structural deformation modes. Modifications may include machining the shaft and / or sleeve, and / or forming new shafts and / or sleeves having the desired variations of the shaft and sleeve used when determining the thermal and structural deformation modes at 1602. For example, some grooves in the groove may be made deeper than others. Additionally or alternatively, some grooves in the groove may be rounded, sharp, tapered, or otherwise reshaped. Additionally or alternatively, a portion of the shaft may be machined to have a smaller outer diameter. Additionally or alternatively, a portion of the sleeve may be machined to have a larger inner diameter.

[0096] In some examples, 1604 also includes 1608, where the groove pattern is modified according to the determined thermal and structural deformation patterns. The groove pattern can be modified to have different segment lengths. Additionally or alternatively, the groove pattern can be modified to include segments without grooves (e.g., groove-free segments). Additionally or alternatively, the groove ratio and / or groove angle can be modified to vary continuously or segmentally. Because the grooves are configured to generate pressure at the fluid interface during the rotation of a rotating component (e.g., a shaft), modifying the groove pattern can modify the flow pattern of the lubricant.

[0097] Method 1600 ends after 1604. By completing method 1600, a hydrodynamic bearing according to this disclosure is formed. The hydrodynamic bearing can then be incorporated into a system (e.g., a CT imaging system) under conditions corresponding to the thermal and structural deformation modes determined at 1602, while reducing lubricant loss. Because the modification counteracts the effects of thermal and structural deformation on the local pressure driving the lubricant fluid flow, the modified hydrodynamic bearing is less likely to experience lubricant insufficiency compared to bearings with a constant axial sleeve inner diameter, a constant axial shaft outer diameter, and a constant axial shaft groove depth.

[0098] The technical effect of the hydrodynamic bearings disclosed herein is to reduce lubricant loss (e.g., insufficient lubricant) caused by thermal and structural deformation by modifying the geometry of the hydrodynamic bearing according to the expected thermal and structural deformation patterns. In this way, the effects of thermal and structural deformation on the lubricant flow pattern can be at least partially mitigated, thereby reducing the likelihood of lubricant being pumped out of the bearing. Therefore, during the operation of a system including the hydrodynamic bearings of this disclosure (e.g., an imaging system), the characteristics of the hydrodynamic bearings, such as damping capacity and stiffness, can be maintained. Furthermore, since less fluid is pumped toward the seals, the number and / or complexity of one or more seals in the system including the bearing can be reduced.

[0099] This disclosure also provides support for a hydrodynamic bearing comprising: a rotating component and a stationary component, the stationary component including a surface having a plurality of grooves arranged in a groove pattern and configured to generate pressure at a fluid interface during rotation of the rotating component, wherein one or more of the following: groove depth, diameter of the rotating component, sill-to-groove ratio, groove cross-sectional shape, groove angle, or diameter of the stationary component varies axially according to a desired thermal and structural deformation mode. In a first example of the system, the rotating component is a sleeve circumferentially surrounding a stationary component, the stationary component being a shaft. In a second example of the system, optionally including the first example, the profile of the groove depth is a mirror image of the desired thermal and structural deformation mode. In a third example of the system, optionally including one or both of the first and second examples, the groove pattern includes segments without grooves. In a fourth example of the system, optionally including one or more of the first to third examples, or each of them, the groove pattern is a herringbone pattern including axially arranged segments, and the grooves are parallel and linear within each segment. In a fifth example, which optionally includes one or more of the first to fourth examples, or each of them, the segments have different axial lengths. In a sixth example, which optionally includes one or more of the first to fifth examples, or each of them, the fluid interface comprises liquid metal disposed in the gap between the rotating component and the stationary component. In a seventh example, which optionally includes one or more of the first to sixth examples, or each of them, the groove depth, the diameter of the rotating component, the groove-to-groove ratio, the groove cross-sectional shape, the groove angle, and / or the diameter of the stationary component varies symmetrically or asymmetrically axially. In an eighth example, which optionally includes one or more of the first to seventh examples, or each of them, the hydrodynamic bearing is included in the X-ray source of the imaging system. In a ninth example, which optionally includes one or more of the first to eighth examples, or each of them, the hydrodynamic bearing comprises one or more journal bearings and / or thrust bearings.

[0100] This disclosure also provides support for an X-ray source having a hydrodynamic bearing, the X-ray source comprising: a sleeve and a shaft, the shaft including an outer surface having a plurality of grooves configured to generate pressure at a liquid metal interface during rotation of the sleeve about the shaft, wherein one or more of the sleeve inner diameter, shaft outer diameter, groove angle, groove cross-sectional shape, sill-to-slot ratio, and groove depth vary axially according to a desired thermal and structural deformation mode. In a first example of the system, the effects of the thermal and structural deformation mode and the axial variation on the fluid flow pattern at the liquid metal interface are offset, thereby preventing fluid from being pumped out of the hydrodynamic bearing. In a second example of the system, optionally including the first example, the sleeve inner diameter, shaft outer diameter, groove angle, groove cross-sectional shape, sill-to-slot ratio, and / or groove depth vary axially asymmetrically. In a third example of the system, optionally including one or both of the first and second examples, the desired thermal and structural deformation mode depends on the material properties of the sleeve and shaft and the operating conditions. In a fourth example, which optionally includes one or more of the first to third examples, or each of them, the system comprises multiple grooves arranged in a groove pattern that varies axially such that the segments of the groove pattern have different lengths and / or some segments have no grooves. In a fifth example, which optionally includes one or more of the first to fourth examples, or each of them, the system comprises multiple grooves arranged in a groove pattern having segments, wherein the sleeve inner diameter, shaft outer diameter, groove angle, groove cross-sectional shape, sill-to-groove ratio, and / or groove depth vary continuously or axially according to the segments. In a sixth example, which optionally includes one or more of the first to fifth examples, or each of them, the profile of the groove depth is proportional to the expected thermal and structural deformation modes, and deeper grooves are located at positions where the expected thermal and structural deformation modes have greater amplitudes. In a seventh example, which optionally includes one or more of the first to sixth examples, or each of them, the grooves in the deformation region where thermal and structural deformation is expected are made shallower, thereby reducing the pumping intensity of the deformation region and allowing the undeformed region to balance the effect on lubricant pumping caused by the deformation region. In an eighth example, which optionally includes one or more of the first to seventh examples, or each of them, the hydrodynamic bearing includes a journal bearing and / or a thrust bearing. In a ninth example, which optionally includes one or more of the first to eighth examples, or each of them, the multiple grooves are herringbone grooves.

[0101] Figures 1 to 7 , Figure 9 , Figure 11 , Figures 13 to 15 and Figure 17 An exemplary configuration with approximate locations is shown. Figures 3 to 4The figures are shown approximately to scale; however, other relative dimensions may also be used. As used herein, unless otherwise specified, the term “approximately” is understood to mean ±5% of the range.

[0102] In at least one example, if shown as being in direct contact or directly connected to each other, such elements may be referred to as being in direct contact or directly connected, respectively. Similarly, in at least one example, elements shown as being adjacent to each other may be referred to as being adjacent to each other, respectively. For example, components placed in coplanar contact may be referred to as being in coplanar contact. Furthermore, in at least one example, elements positioned spaced apart from each other and having only space between them without other components may be described as such. Moreover, elements shown as being above / below each other, on opposite sides of each other, or on the left / right side of each other may be described relative to each other. Additionally, as shown, in at least one example, the topmost element or point of the element may be referred to as the “top” of the component, and the bottommost element or point of the element may be referred to as the “bottom” of the component. As used herein, top / bottom, upper / lower, above / below may be relative to the vertical axis of the figure and may be used to describe the positioning of elements in the figure relative to each other. Thus, in one example, an element shown as being above other elements is vertically positioned above the other elements. For example, the shapes of the elements depicted in the figures may be described as having those shapes (e.g., such as circular, straight, planar, curved, rounded, chamfered, angled, etc.). Furthermore, in at least one example, elements shown as intersecting each other may be described as intersecting elements or intersecting with each other. Additionally, in one example, an element shown as being inside or outside another element may be described as such. Moreover, these components may be described as relating to the reference axes included in the figures.

[0103] Unless otherwise specified, features described as axial may be approximately parallel to the referenced axis. Unless otherwise specified, features described as anti-axial may be approximately perpendicular to the referenced axis. Unless otherwise specified, features described as radial may circumferentially surround or extend outward from an axis, such as the referenced axis; or a component or feature previously described as radial relative to the referenced axis.

[0104] Features described as longitudinal can be approximately parallel to the longitudinal axis. A transverse axis can be perpendicular to both the longitudinal and vertical axes. Features described as transverse can be approximately parallel to the transverse axis. A vertical axis can be perpendicular to both the transverse and longitudinal axes. Features described as vertical can be approximately parallel to the vertical axis.

[0105] It should be understood that the configurations and routines disclosed herein are exemplary in nature, and these specific implementations should not be considered limiting, as many variations are possible. Furthermore, unless explicitly stated otherwise, the terms “first,” “second,” “third,” etc., are not intended to indicate any order, position, quantity, or importance, but are merely used as markers to distinguish one element from another. The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations disclosed herein, as well as other features, functions, and / or characteristics.

[0106] The following claims specifically point to certain combinations and sub-combinations that are considered novel and non-obvious. These claims may refer to a "one" element or a "first" element or its equivalent. Such claims should be understood to include combinations of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and / or properties may be claimed by amending these claims or by presenting new claims in this application or related applications. Such claims, whether broader or narrower in scope than the original claims, identical or different, are considered to be included within the subject matter of this disclosure.

Claims

1. A hydrodynamic bearing (900, 700, 500, 1500), said hydrodynamic bearing comprising: Rotating components; and A stationary component comprising a surface having a plurality of grooves (506, 416) arranged in a groove (506) pattern and configured to generate pressure at a fluid interface (320, 408) during rotation (106) of the rotating component, wherein one or more of the groove (506) depth (704), the diameter (514) of the rotating component, the tier-to-groove ratio (506), the groove cross-sectional shape, the groove angle (1140), or the diameter of the stationary component varies axially according to a desired thermal and structural deformation mode (650, 550).

2. The hydrodynamic bearing (900, 700, 500, 1500) according to claim 1, wherein the rotating component is a sleeve (504, 404, 1502, 306, 1504) circumferentially surrounding the stationary component, and the stationary component is a shaft (1402, 702, 402, 308, 1302, 1102, 502, 902).

3. The hydrodynamic bearing (900, 700, 500, 1500) according to claim 1, wherein the profile of the groove (506) depth (704, 704) is a mirror image of the expected thermal and structural deformation mode (650, 550, 650, 550).

4. The hydrodynamic bearing (900, 700, 500, 1500) according to claim 1, wherein the groove pattern includes segments (1304) without grooves.

5. The hydrodynamic bearing (900, 700, 500, 1500) according to claim 1, wherein the groove pattern is a herringbone pattern comprising axially arranged segments (1112), and the grooves (506, 416) are parallel and linear within each segment of the segments (1112).

6. The hydrodynamic bearing (900, 700, 500, 1500) according to claim 5, wherein the segments (1304, 1112) have different axial lengths (1122).

7. The hydrodynamic bearing (900, 700, 500, 1500) according to claim 1, wherein the fluid interface (320, 408) comprises liquid metal disposed in the gap (508) between the rotating component and the stationary component.

8. The hydrodynamic bearing (900, 700, 500, 1500) according to claim 1, wherein the hydrodynamic bearing (900, 700, 500, 1500) comprises one or more journal bearings and / or thrust bearings.

9. An X-ray source (300, 104) having hydrodynamic bearings (900, 700, 500, 1500), said X-ray source (300, 104) comprising: Sleeves (504, 404, 1502, 306, 1504); and A shaft (1402, 702, 402, 308, 1302, 1102, 502, 902) includes an outer surface (518) having a plurality of grooves (506, 416) configured to generate pressure in a liquid metal interface (320, 320) during rotation of the sleeve (504, 404, 1502, 306, 1504) about the shaft (1402, 702, 402, 308, 1302, 1102, 502, 902), wherein one or more of the sleeve inner diameter (514), shaft outer diameter (512), groove angle (1140), groove cross-sectional shape, sill-to-groove ratio, and groove depth (704) vary axially according to a desired thermal and structural deformation mode (650, 550).

10. The X-ray source (300, 104) according to claim 9, wherein the effects of the thermal and structural deformation modes (650, 550) and the axial changes on the fluid flow pattern in the liquid metal interface (320, 320) are offset, thereby preventing fluid from being pumped out of the hydrodynamic bearing (900, 700, 500, 1500).

11. The X-ray source (300, 104) according to claim 9, wherein the inner diameter of the sleeve (514), the outer diameter of the shaft (512), the groove angle (1140), the cross-sectional shape of the groove, the stage-to-groove ratio and / or the groove depth (704) vary axially asymmetrically.

12. The X-ray source (300, 104) according to claim 9, wherein the plurality of grooves (506, 416) are arranged in a groove (506) pattern, the groove pattern being axially varied such that segments (1112) of the groove pattern have different lengths (1122) and / or some segments of the segments (1304) have no grooves (506, 416).

13. The X-ray source (300, 104) of claim 9, wherein the contour of the depth (704, 704) of the groove (506) is proportional to the expected thermal and structural deformation mode (650, 550, 650, 550), and deeper grooves (506, 416) are positioned at locations with greater amplitude of the expected thermal and structural deformation mode (650, 550, 650, 550).

14. The X-ray source (300, 104) of claim 9, wherein the grooves (506, 416) are made shallower in the deformation region where thermal and structural deformation is expected to occur, thereby reducing the pumping intensity of the deformation region and causing the undeformed region to balance the effect of the deformation region on lubricant pumping.

15. The X-ray source (300, 104) according to claim 9, wherein the hydrodynamic bearing (900, 700, 500, 1500, 500) comprises journal bearing (900, 700, 500) and / or thrust bearing (900, 700, 500).

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