Electric submersible pump rotor assembly with bearing spacer configured for thrust washer support

Abstract

An exemplary rotor assembly for an ESP motor can comprise a rotor module concentrically disposed on a drive shaft; a bearing assembly concentrically disposed about the drive shaft in proximity to the rotor module; a thrust washer concentrically disposed about the drive shaft and axially between the bearing assembly and the rotor module; and an axial support flange disposed concentrically about the drive shaft and axially between the thrust washer and the rotor module. In some embodiments, the axial support flange can abut the thrust washer. Disclosed embodiments may reduce dishing of the thrust washer when the motor is in operation, which can be particularly useful in embodiments having concavities formed in an axial face of the bearing bushing or the thrust washer which can influence flow of lubrication fluid between the bushing and the thrust washer to create a hydrodynamic force.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part of and claims priority to U.S. patent application Ser. No. 18 / 644,477 filed Apr. 24, 2024, the entire contents of which are incorporated herein by reference.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.FIELD

[0003] This disclosure relates generally to the field of pumping. More particularly, this disclosure relates to the field of electric submersible pumps for use downhole in a well. Still more particularly, this disclosure relates to an electric submersible pump rotor assembly with a hydrodynamic bearing.BACKGROUND

[0004] Electric submersible pump (ESP) assemblies may be used to artificially lift fluid to the surface, for example in deep wells such as oil or water wells. ESP assemblies are commonly used in the oil and gas industry to extract fluids from underground reservoirs. By way of example, the artificial lift provided by ESP assemblies may be useful in situations when the reservoir does not have sufficient energy to allow the well to naturally produce effectively, or when an additional boost to production of the well is desired.

[0005] A typical ESP assembly comprises, from bottom to top, an electric motor, a seal unit, a pump intake, and a pump (e.g. typically a centrifugal pump), which are all mechanically connected together with shafts and shaft couplings. The electric motor supplies torque to the shafts, which provides power to the centrifugal pump. The electric motor is isolated from a wellbore environment by a housing and by the seal unit. The seal unit can act as an oil reservoir for the electric motor. The oil can function both as a dielectric fluid and as a lubricant in the electric motor. The seal unit also may provide pressure equalization between the electric motor and the wellbore environment.

[0006] The centrifugal pump is configured to transform mechanical torque received from the electric motor via a drive shaft to fluid pressure which can lift fluid up the wellbore. For example, the centrifugal pump typically has rotatable impellers within stationary diffusers. A shaft extending through the centrifugal pump is operatively coupled to the motor, and the impellers of the centrifugal pump are rotationally coupled to the shaft. In use, the motor can rotate the shaft, which in turn can rotate the impellers of the centrifugal pump relative to and within the stationary diffusers, thereby imparting pressure to the fluid within the centrifugal pump. The electric motor is generally connected to a power source located at the surface of the well using a cable and a motor lead extension. The ESP assembly is placed into the well and usually is inside a well casing. In a cased completion, the well casing separates the ESP assembly from the surrounding formation. In operation, perforations in the well casing allow well fluid to enter the well casing and flow to the pump intake for transport to the surface.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] For a more complete understanding of the present disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts.

[0008] FIG. 1 is a schematic illustration of an exemplary electric submersible pump (ESP) assembly disposed in a wellbore, according to an embodiment of the disclosure;

[0009] FIG. 2 is a cross-sectional view of an exemplary motor for the electric submersible pump assembly of FIG. 1, according to an embodiment of the disclosure;

[0010] FIG. 3 is an exploded isometric view of the motor of FIG. 2, according to an embodiment of the disclosure;

[0011] FIG. 4 is a partial cut-away isometric view of an exemplary ESP motor having a plurality of rotor modules with rotor assemblies therebetween, according to an embodiment of the disclosure;

[0012] FIG. 5 is an isometric view of an exemplary rotor assembly for an ESP motor of an ESP pump assembly, according to an embodiment of the disclosure;

[0013] FIG. 6A is schematic axial cross-section view of an exemplary rotor assembly, according to an embodiment of the disclosure;

[0014] FIG. 6B is a schematic axial cross-section view of another exemplary rotor assembly, according to an embodiment of the disclosure;

[0015] FIG. 7 is an axial cross-section view of yet another exemplary rotor assembly, according to an embodiment of the disclosure;

[0016] FIG. 8 is an enlarged portion of the axial cross-section view of the rotor assembly of FIG. 7, according to an embodiment of the disclosure;

[0017] FIG. 9 is an enlarged portion of the axial cross-section view of the rotor assembly of FIG. 7, showing the journal rotor assembly between two adjacent rotor modules, according to an embodiment of the disclosure;

[0018] FIG. 10 is an enlarged portion of the axial cross-section view of the rotor assembly of FIG. 7, showing the journal rotor assembly at the motor head end of the shaft, according to an embodiment of the disclosure;

[0019] FIG. 11 is an axial cross-section view of the rotor assembly of FIG. 7, according to an embodiment of the disclosure;

[0020] FIG. 12 is an enlarged portion of the axial cross-section view of the rotor assembly of FIG. 11, according to an embodiment of the disclosure;

[0021] FIG. 13 is an isometric view of an exemplary bushing assembly, according to an embodiment of the disclosure;

[0022] FIG. 14 is a perspective view of the bushing of FIG. 12 according to an embodiment of the disclosure;

[0023] FIG. 15A is a schematic diagram of the interface between the bushing and the thrust washer, according to an embodiment of the disclosure;

[0024] FIG. 15B is a schematic diagram of the interface between the bushing and the thrust washer, according to another embodiment of the disclosure;

[0025] FIG. 15C is a schematic diagram of the interface between the bushing and the thrust washer, according to yet another embodiment of the disclosure;

[0026] FIG. 16 is a perspective view of the bushing of FIG. 12, according to another embodiment of the disclosure;

[0027] FIG. 17 is a perspective view of the bushing of FIG. 12, according to yet another embodiment of the disclosure;

[0028] FIG. 18A is a perspective view of the bushing of FIG. 12, according to yet another embodiment of the disclosure;

[0029] FIG. 18B is a perspective view of the thrust washer of FIG. 12, according to the embodiment of FIG. 18A;

[0030] FIG. 19 is a schematic illustration of an exemplary axial load causing dishing of an exemplary thrust washer of an exemplary rotor assembly, according to an embodiment of the disclosure;

[0031] FIG. 20 is a partial axial cross-section view of an exemplary rotor assembly, according to an embodiment of the disclosure;

[0032] FIG. 20A is an isometric view of an exemplary thrust washer support with an exemplary thrust washer disposed thereon, according to an embodiment of the disclosure;

[0033] FIG. 20B is an isometric view of the thrust washer support of FIG. 20A without the thrust washer, according to an embodiment of the disclosure;

[0034] FIG. 21 is a schematic illustration of an exemplary axial load causing reduced dishing of an exemplary thrust washer of an exemplary rotor assembly which is supported by an exemplary axial support flange, according to an embodiment of the disclosure;

[0035] FIG. 22 is a partial axial cross-section view of another exemplary rotor assembly, according to an embodiment of the disclosure;

[0036] FIG. 22A is a partial isometric view of the thrust washer and thrust washer support of FIG. 22, according to an embodiment of the disclosure.

[0037] FIG. 23 is a partial axial cross-section view of yet another exemplary rotor assembly, according to an embodiment of the disclosure.DETAILED DESCRIPTION

[0038] It should be understood at the outset that although illustrative implementations of one or more embodiments are illustrated below, the disclosed systems and methods may be implemented using any number of techniques, whether currently known or not yet in existence. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, but may be modified within the scope of the appended claims along with their full scope of equivalents.

[0039] As used herein, orientation terms “upstream,”“downstream,”“up,” and “down” are defined relative to the direction of flow of well fluid in the well casing. “Upstream” is directed counter to the direction of flow of well fluid, towards the source of well fluid (e.g., towards perforations in well casing through which hydrocarbons flow out of a subterranean formation and into the casing). “Downstream” is directed in the direction of flow of well fluid, away from the source of well fluid. “Down” is directed counter to the direction of flow of well fluid, towards the source of well fluid. “Up” is directed in the direction of flow of well fluid, away from the source of well fluid.

[0040] Disclosed embodiments relate generally to rotor assemblies for an ESP motor (e.g. for use with a pump to form an ESP assembly for use downhole in a well to pump formation fluids from the well formation to the surface), with the rotor assemblies being configured to address differential thermal expansion and the related issues arising therefrom.

[0041] Turning now to FIG. 1, an exemplary producing well environment 100 is described. In an embodiment, the environment 100 comprises a wellhead 101 above a wellbore 102 located at the surface 103. A casing 104 is provided within the wellbore 102. For convenience of reference, FIG. 1 provides a directional reference comprising three coordinate axes—an X-axis 160 where positive displacements along the X-axis 160 are directed into the sheet and negative displacements along the X-axis 160 are directed out of the sheet; a Y-axis 162 where positive displacements along the Y-axis 162 are directed upwards on the sheet and negative displacements along the Y-axis 162 are directed downwards on the sheet; and a Z-axis 164 where positive displacements along the Z-axis 164 are directed rightwards on the sheet and negative displacements along the Z-axis 164 are directed leftwards on the sheet. In the embodiment of FIG. 1, the Y-axis 162 is approximately parallel to a central axis of a vertical portion of the wellbore 102.

[0042] An exemplary electric submersible pump (ESP) assembly 106 may be deployed downhole in a well within the casing 104 and may comprise an optional sensor unit 108, an electric motor 110 which may include a motor head 111, a seal unit 112, an electric power cable 113, a pump intake 114, a centrifugal pump 116, and a pump outlet 118 that couples the centrifugal pump 116 to a production tubing 120. The centrifugal pump 116 may be operatively coupled to the motor 110 by a shaft. In an embodiment, the ESP assembly 106 may employ radial and thrust bearings in several places, for example in the electric motor 110, in the seal unit 112, and / or in the centrifugal pump 116. In an embodiment, the ESP assembly 106 can comprise a gas separator that may employ one or more thrust bearings. The motor head 111 may couple the electric motor 110 to the seal unit 112. The electric power cable 113 may connect to a source of electric power at the surface 103 and to the electric motor 110, for example being configured to provide power from the source of electric power at the surface 103 to the electric motor 110.

[0043] In operation, the casing 104 is pierced by perforations 140, and reservoir fluid 142 flows through the perforations 140 into the wellbore 102. The fluid 142 flows downstream in an annulus formed between the casing 104 and the ESP assembly 106, is drawn into the pump intake 114, is pumped by the centrifugal pump 116, and is lifted through the production tubing 120 to the wellhead 101 to be produced at the surface 103. The fluid 142 may comprise hydrocarbons such as oil and / or gas, water, or both hydrocarbons and water.

[0044] While the example illustrated in FIG. 1 relates to land-based subterranean wells, similar ESP systems can be used in a subsea environment and / or may be used in subterranean environments located on offshore platforms, drill ships, semi-submersibles, drilling barges, etc. And while the wellbore is shown in FIG. 1 as being approximately vertical, in other embodiments, the wellbore may be horizontal, deviated, or any other type of well. Also, while the pump of the ESP is described with respect to FIG. 1 as a centrifugal pump, other types of pumps (such as a rod pump, a progressive cavity pump, any other type of pump suitable for the system, or combinations thereof) may be used instead.

[0045] As shown in FIGS. 2-3, an exemplary motor 110 of the ESP assembly includes a housing 205, a stator 210, a rotor 215, and a drive shaft 220. The housing 205 may comprise a hollow cylinder or tube and is configured to protect the internal components of the motor 110 from the external environment. The stator 210 may also comprise a hollow cylinder and is secured to the housing 205 (e.g. to the inner surface of the housing 205) so as to be stationary within the housing 205. The stator 210 may comprise a plurality of laminations, which may be thin sheets of steel, iron, or bronze, wrapped by a plurality of electrically conductive windings. When energized, the windings generate a rotating magnetic field for interaction with the rotor 215 to induce rotation of the rotor 215. The rotor 215 may also comprise a hollow cylinder and is concentrically arranged between the stator 210 and the drive shaft 220, for example with the drive shaft 220 typically extending longitudinally along the centerline of the motor 110, the rotor 215 disposed around the drive shaft 220, and the stator 210 disposed around the rotor 215, within the housing 205. The rotor 215 may be rotatable within the stator 210 and secured to the drive shaft 220, such that rotation of the rotor 215 drives the drive shaft 220. In embodiments, the motor 110 may be a two or more pole motor, a three-phase squirrel cage induction motor, a permanent magnet motor (PMM), a hybrid PMM, or other motor configuration.

[0046] Depending on the power requirements of the motor 110, the rotor 215 can be an assembly which typically includes a number of rotor modules, which together jointly form the rotor assembly 215, with each rotor module secured to the drive shaft 220. The rotational magnetic field of the stator 210 when energized can induce rotation of the rotor 215, and thereby the drive shaft 220, with the drive shaft 220 transmitting rotational torque from the motor 110 to the pump 116. As shown in FIG. 4, the rotor modules 405 (jointly forming the rotor 215) can be spaced apart from each other along the drive shaft 220, with a rotor bearing assembly 410 located between adjacent rotor modules 405. Rotor bearing assemblies 410 can also be located at the top of the uppermost rotor module 405 and / or the bottom of the lowermost rotor module 405 (e.g. at the top and bottom of the rotor). In some embodiments, the rotor bearing assembly 410 can be a hydrodynamic rotor bearing assembly. Typically, each rotor bearing assembly 410 is configured to support the rotor 215 at predefined axial positions to maintain correct radial alignment of the drive shaft 220 during motor operation.

[0047] As discussed in more detail below with respect to specific embodiments, rotor bearing assemblies 410 can comprise a journal sleeve and a bushing assembly. The journal sleeve may be concentrically disposed around and secured to the drive shaft 220 to rotate with the drive shaft 220. In embodiments, the inner journal sleeves can be configured to space each rotor module 405 evenly on the drive shaft 220. The outer bushing assembly may be concentrically located around the inner journal sleeve, and the bushing assembly may fixedly engage into the stator lamination (e.g. the bushing assembly is configured to engage the inner surface of the stator 210 to prevent rotation therein). The engagement into the stator lamination is required to ensure that the bushing assembly does not spin during operation, but instead provides a stationary surface within which the inner journal sleeve can rotate, to produce a hydrodynamic lubricating film.

[0048] During start-up and in operation, the rotor 215 may be heated, for example due to friction, and thereby expands radially and axially. Since materials with different coefficient of thermal expansion (CTE) may be used in rotor construction, the components of the rotor 215 (e.g. with different CTE) can expand at different rates. Further, the expansion between the drive shaft 220 and one or more of the components of the rotor 215 can vary.

[0049] A snap ring or similar end support structure can be installed at one end of the shaft to support the mass of the rotor assembly 215 components (e.g. with respect to gravity). The mass of each rotor module 405 can be transferred to the next (e.g. lower) rotor module 405 (e.g. through the rotor bearing assemblies 410 disposed between adjacent rotor modules 405). The components of the last (e.g. lowest / bottom) rotor module 405, such as the last thrust washer, may be subjected to the weight of all components above. The strength of this polymeric thrust washer, for example, could be the limiting factor for the number of rotor modules 405 that can be used in a rotor assembly 215.

[0050] Another snap ring can be installed at the opposite end of the shaft 220, at a pre-defined distance from the first / upper most rotor module 405 to ensure that there is enough expansion length (e.g. for thermal expansion). In other embodiments a spring loaded mechanism can fill the gap between the snap ring and rotor module 405. The rotor modules 405 can be (axially) loose on the shaft 220, and they can be operable to shift axially during installation into the stator 210 and / or during operation of the motor 110. The stator 210 may require allowance for the rotor 215 thermal growth, to ensure that the rotor end bearings cannot extend out from its support in the stator lamination stack.

[0051] In embodiments, various loads can be applied to one or more component of a rotor assembly, which can in some instances negatively impact the rotor assembly. For example, ESPs with certain types of motors (for example, permanent magnet motors) can exert a considerable load on the bearing due to the magnetic attraction to the stator. This can magnify the bearing load by two to ten times the gravitational load from the rotor mass. This force can create a large axially disposed frictional sliding force in the axial direction. A reaction load must be applied above this sliding force in order to move the bearing axially. In other words, the thrust capacity of the end of the bearing needs to be higher than the reaction load. In vertical operation of the motor, the gravitational weight of the outer bearing sleeve may bear down onto the thrust washer face. In other words, the outer bearing sleeve typically should have enough capacity to support this weight. In all orientations of the motor, the components may thermally expand to different degrees. This can lead to situations (due to the long lengths of the downhole motors) where the stationary outer bearing sleeve comes into axial contact with the rotor axial face due to the different relative rotor thermal growths. If the rotor thermal growth is larger than the axial gaps, high loads will be generated in the case in which outer bearing sleeve does not move. This load may climb until the applied “thermal growth” reaction force exceeds the sliding force.

[0052] The axial face of the conventional bearing may have insufficient load capacity to carry such loads and contact may occur between the rotating rotor face and the static bearing face. A thrust washer of the bearing may start to wear. Additionally, contact can generate heat that can cause the material to indent as its strength becomes too weak to resist the applied force. As the failure progresses, the static sleeve may dig into the washer, which may eventually cause the thrust washer to fail. The digging in also may also lead to increased radial load on the bearing, which can ultimately lead to a radial bearing failure. The eventual consequence of the bearing failures may be motor failure and ultimate failure of the ESP.

[0053] Turning now to the figures in detail for more specific examples, FIG. 5 illustrates a typical rotor assembly 215 of an electric motor 110 (for example, of an ESP assembly). In embodiments, the electric motor 110 can be a permanent magnet motor. Typically, the rotor assemblies 215 shown in the figures belong to such a permanent magnet motor (PMM). However, alternate embodiments may include an electric motor of any conventional type, i.e. an induction motor or a hybrid PMM containing elements of both permanent magnet and induction motors. The rotor assembly 215 of the PMM utilizes permanent magnets to generate the electromagnetic field, compared to induction motors where the magnetic field is generated by inducing a current in rotor interconnected bars made from copper.

[0054] A rotor assembly 215 embodiment can comprise a single drive shaft 220, a plurality of magnetic rotor modules 405, and a plurality of rotor bearing assemblies 410 (e.g. typically radial hydrodynamic rotor bearing assemblies). Typically, all rotor modules 405 and / or all rotor bearing assemblies 410 of a rotor assembly 215 can be substantially identical. A rotor bearing assembly 410 can be disposed between adjacent rotor modules 405. In some embodiments, the rotor assembly 215 can also include a pre-loading mechanism 505 (as shown in FIG. 5 for example), which can provide thermal expansion compensation for the rotor assembly 215. In the embodiment shown in FIG. 5, the pre-loading mechanism 505 is disposed at the non-drive end (e.g. the motor base) of the rotor assembly 215, and it can be configured to act against the gravitational load 520 created by all the rotor modules 405 and journal rotor bearing assemblies 410 installed on the shaft 220 (as well as addressing differential thermal expansion, for example). Alternatively, or in conjunction, the pre-loading mechanism 505 can be positioned at the drive end (e.g. the motor head) of the shaft 220, according to other embodiments and / or distributed throughout the assembly (e.g. with springs and / or snap rings at various locations along the length).

[0055] FIGS. 6A and 6B illustrate schematically alternate stacking embodiment options for components of a rotor assembly 215. In the embodiment of FIG. 6A, a journal sleeve 770 of a rotor bearing assembly 410 is installed between each adjacent pair of rotor modules 405. The journal sleeve 770 may be installed directly onto the drive shaft 220 (e.g. concentric with the drive shaft 220) and may axially contact any adjacent rotor modules 405 (which are also concentrically disposed on the drive shaft 220). This method of stacking the rotor modules 405 and journal sleeves 770 onto the shaft 220 may have all rotor module 405 components compressed between two adjacent journal sleeves 770 located on both sides of the rotor module 405. A thrust washer 730 may be trapped between the bearing and the rotor module.

[0056] An alternate stacking method is shown in FIG. 6B. For example, the cage rings 725, rotor bars 720, and the thrust washers 730 can be disconnected from (e.g. moved out of) the axial stack of supporting components of the rotor assembly. Each rotor module 405 (e.g. comprised here with respect to axial force transmission of only the lamination stack 740 and the end laminations 745, both made from steel) can be spaced by a steel support sleeve 750 (as will be discussed in more detail below with respect to specific embodiments). While the support sleeve 750 may be steel in some embodiments, in other embodiments, the support sleeve can be formed of other materials with CTE similar to that of the lamination stack 740, end laminations 745, and / or drive shaft 220. In embodiments, the bearing assembly can be disposed on the support sleeve 750, as discussed in more detail below. In some embodiments, the thrust washers 730 may be connected to the support sleeve 750 to prevent them moving axially as shown in later embodiments.

[0057] The thrust washer does not necessarily have to be a separate component. In some embodiments, the thrust washer can be absent, and instead the end face of the rotor module 405, case ring 725, bearing spacer 1210, or any other suitable element may have a face that acts as the face of the thrust washer. This end face may have any of the features (e.g., concavities 611, grooves 612, etc.) discussed herein with respect to the thrust washer.

[0058] FIG. 7 depicts a longitudinal cross-section of an exemplary rotor assembly 215 embodiment, illustrating the exemplary rotor assembly 215 embodiment in greater detail, showing the overall rotor assembly 215 construction. FIG. 8, FIG. 9, and FIG. 10 illustrate in more detail portions of the rotor assembly 215 of FIG. 7. For example, FIG. 8 illustrates an exemplary rotor module 405, illustrating interaction with other components based on the proposed stacking method shown in FIG. 7. FIG. 9 focuses on the proposed exemplary stacking method (e.g. using the support sleeve 750) which can be used between any two adjacent (e.g. magnetic) rotor modules 405 on the shaft 220. FIG. 10 focuses on the exemplary retention and stacking method at the drive end (e.g. at the motor head) of the shaft 220.

[0059] The magnetic rotor module 405 shown in FIG. 8 may include the lamination stack 740, the end laminations 745, the plurality of cage bars 720, and the plurality of cage rings 725. The lamination stack 740, plurality of cage bars 720 as a whole, and each cage ring 725 may be concentrically disposed about the drive shaft 220. The lamination stack 740 can be made from a plurality of stamped thin sheets of electrical steel, which may be assembled together by bonding, by clinching, or by use of interference fit, etc. to another component (e.g. the drive shaft 220). In embodiments, the lamination stack 740 can include the desired geometry (e.g. pockets) to accept a plurality of permanent magnets 605, which may be made from rare earth such as Samarium Cobalt or Neodymium Iron Boron. The end laminations 745 can be disposed on each end of the lamination stack 740, for example to trap the magnets in the lamination stack pockets. The end laminations 745 may be thicker steel than the lamination stack 740. The plurality of electrically conductive (e.g. copper) cage bars 720 can be installed inside a plurality of longitudinally extending holes in the lamination stack 740 (e.g. with the longitudinally extending holes disposed around the drive shaft 220), and may protrude from each end of the lamination stack 740. The electrically conductive (e.g. brass) cage rings 725, can be disposed on each end of the lamination stack 740, for example connected to the plurality of cage bars 720 by interference fit or soldering to create a squirrel cage (e.g. similar to an induction motor). In other embodiments, the permanent magnets 605 can be omitted, making the rotor module 405 a standard induction rotor module.

[0060] FIG. 9 shows a rotor bearing assembly 410, which may support the rotor at predefined axial positions to maintain radial alignment of the shaft 220 during the motor operation. The rotor bearing assembly 410 can comprise an inner journal sleeve 770 and an outer bushing assembly 510, for example with the bushing 610 configured to be disposed concentrically about the journal sleeve 770. In some embodiments, the inner journal sleeve 770 can be secured to the shaft 220 through a support sleeve 750 (which typically may be steel or some other material with CTE similar to the lamination stack 740, the end laminations 745, and / or the drive shaft 220). For example, anti-rotation elements 1120 (e.g. helical springs or elastomeric rings) may rotationally fix the journal sleeve 770 to the support sleeve 750, so that the journal sleeve 770 rotates with the support sleeve 750 (and thereby the shaft 220). The support sleeve 750 may be concentrically disposed about the drive shaft 220 (e.g. between two adjacent rotor modules 405) and can be configured to rotate with the drive shaft 220 while being able to slide axially with respect to the shaft 220. For example, the support sleeve 750 can be keyed to the shaft 220 (e.g. with one or more keys in corresponding longitudinally extending key slots in the shaft) so as to be allowed to slide along the shaft 220 axially while rotating with the shaft 220. In other embodiments the inner journal sleeve 770 may be directly mounted and keyed to the shaft 220. A thrust washer 730 may be trapped between the bearing and the rotor module.

[0061] The anti-rotation element's 1120 secondary function can be to axially center the inner journal sleeve 770 between the two adjacent rotor modules 405. The outer bushing assembly 510 may be concentrically located around the journal sleeve 770 and may engage into the stator lamination. The engagement into the stator lamination may ensure that the bushing assembly 510 does not spin during operation. Rather, the bushing assembly 510 can provide a stationary surface for journal sleeve 770 to rotate in, which may allow it to produce hydrodynamic lubricating film. The support sleeve 750 also can space each rotor module 405 evenly on the shaft 220. The support sleeve 750 in FIG. 9 is configured to provide axial support to the lamination stack 740 of adjacent rotor modules 405 through the end laminations 745, for example touching / abutting the adjacent end lamination 745 on both adjacent magnetic rotor modules 405 (e.g. on either side) at the contact surface 1018. The adjacent cage rings 725 of the magnetic rotor modules 405 of FIG. 9 may be concentrically disposed around the steel support sleeve 750, having a radial clearance round the steel support sleeve 750. In this embodiment, the thrust washers 730 can be mounted onto the support sleeve 750, on both ends (e.g. with the rotor bearing assembly 410 disposed therebetween). For example, a thrust washer 730 may be disposed between the rotor bearing assembly 410 and the adjacent rotor module 405. In embodiments, the thrust washers 730 can be mounted on the support sleeve 750 by an interference fit method, although other methods of assembly can be implemented, such as anti-rotation keys / tabs and axial retaining shoulders / spigots. The design of the support sleeve 750 can create defined axial clearances 1016 and 1017 between the thrust washer 730 and the rotor bearing assembly 410 and the cage ring 725 of the magnetic rotor module 405, respectively. Clearance 1016 may allow the thrust washers 730 to not contact the bushing assembly 510 during the motor operation (e.g. when the rotor assembly 215 is rotating inside the stator assembly 210). In other embodiments this gap may close and result in thrust force on the thrust washer 730.

[0062] The end arrangement depicted in FIG. 10 can comprise a snap ring 1205 located in a corresponding groove (e.g. in the exterior of the shaft 220) at a predefined distance from the shaft end on the shaft 220, and a spacer ring 1212 (e.g. axially abutting the snap ring) which may be designed to correspond to the profile of the cage ring 725 of the magnetic rotor module 405. The spacer ring 1212 can be installed concentrically with the steel support 750 with a radial clearance 1019 around the steel support sleeve 750. The spacer ring 1212 can touch / abut the support sleeve 750 axially at the contact area 1018. Other embodiments may include a spring loading mechanism. Clearance 1016 may allow the thrust washers 730 to not contact the bushing assembly 510 during the motor operation (e.g. when the rotor assembly 215 is rotating inside the stator assembly 210). In other embodiments this gap may close and result in thrust force on the thrust washer 703.

[0063] An exemplary outer bushing assembly 510, of the sort which might be used in an ESP motor for use downhole in a well as part of an ESP, is shown in FIGS. 13 and 14. The outer bushing assembly 510 can comprise a bushing 610, one or more anti-rotation tabs 606, one or more biasing elements 705, and one or two retention rings 615. Although FIGS. 13 and 14 illustrates an exemplary embodiment having a plurality of anti-rotation tabs 606, with a corresponding plurality of biasing elements 705, the disclosure is not so limited. The bushing 610 may comprise one or more spring recess 710 extending inward from an outer surface of the bushing 610, one or more axial slot 715 on the outer surface of the bushing 610 (e.g. extending axially, such as approximately parallel to the longitudinal axis of the bushing), and one or more slots 619 of the outer surface having a smaller outer diameter than a main body portion of the bushing 610 (e.g. an inwardly / inset stepped portion). Each axial slot 715 may intersect the corresponding spring recess 710 and axial face 614. The bushing 610 may have additional circular cut outs (e.g. channels 616) to allow oil to bypass the bearing 410. In embodiments, the bushing 610 is substantially cylindrical about a longitudinal axis.

[0064] FIG. 11 illustrates a longitudinal cross-section of an exemplary rotor assembly 215 of an alternate embodiment (e.g. configured for intermediate pre-compression), showing the overall rotor assembly 215 construction. A detailed view of a portion of FIG. 11 is further illustrated in FIG. 12, which focuses on the proposed stacking system of FIG. 11 between any two adjacent magnetic rotor modules 405 on the shaft 220 (e.g. with bearing assembly 410 disposed therebetween on a support sleeve 750).

[0065] Referring to FIGS. 12 and 14, a rotor bearing assembly 410 for an ESP may include a drive shaft 220; a journal sleeve 770 concentrically disposed about and rotationally fixed to the drive shaft 220; a bushing 610 concentrically disposed about and configured to rotate with respect to the journal sleeve 770; and a thrust washer 730 encircling the drive shaft 220. In some embodiments, concavities 611 may be formed in an axial face 614 of the bushing 610 and / or an axial face 731 of the thrust washer 730. The axial face 614 of the bushing 610 may be disposed proximate to the axial face 731 of the thrust washer 730, with the gap or open space of the concavities 611 disposed therebetween. The concavities 611 may be configured to influence flow of lubrication fluid (e.g., oil) between the bushing 610 and the thrust washer 730 to create a hydrodynamic force against the bushing 610 and the thrust washer 730 when the drive shaft 220 rotates. The hydrodynamic force may repel the bushing 610 from the washer 730 (e.g., the bushing 610 may experience force in an axial direction away from the washer 730 and the washer 730 may experience force in an axial direction away from the bushing 610). This may prevent the bushing 610 and the washer 730 from touching, and thus wear on the washer 730 may be greatly reduced or eliminated. Essentially, the washer 730 may ride on an oil film configured to act as a hydrodynamic bearing.

[0066] Grooves 612 may be formed in the axial face 614 of the bushing or the axial face 731 of the thrust washer 730. The grooves 612 may be on whichever surface the concavities 611 are on. The grooves 612 may be configured to guide lubrication fluid radially outward particularly when the clearance 1016 as shown in FIGS. 9, 10 & 12 is closed when thrust washer 730 is in contact with bushing 610. Centrifugal force may carry the fluid through the grooves 612 from an area proximate the inner circumferential surface 618 of the bushing 610 to the outer circumferential surface 617 of the bushing 610 or from the inner circumferential surface 733 of the thrust washer 730 to the outer circumferential surface 732 of the thrust washer 730. The axial face 614 of the bushing 610 may be approximately parallel to the axial face 731 of the thrust washer 730. The concavities 611 may include a converging wedge shape. The converging wedge shape may act as a ramp for the fluid so that the fluid will be forced into a small space between the bushing 610 and the washer 730 and thus cause a pressure increase and thus force. This hydrodynamic force may prevent contact between the bushing 610 and the thrust washer 730 when the drive shaft 220 rotates. The grooves 612 may extend deeper than the concavities 611. In some embodiments, grooves 612 may be formed in the concavities 611. In some embodiments, grooves 612 may be disposed between the concavities 611. In some embodiments, grooves 612 may be formed both in the concavities 611 and between the concavities 611.

[0067] In the embodiment of FIG. 12, the thrust washer is disposed on a thrust washer support 1210 (e.g. with the thrust washer support 1210 concentrically disposed on the shaft 220 and the thrust washer 730 concentrically disposed (e.g. seated) on the thrust washer support 1210). Axially, the thrust washer support 1210 can be disposed between the end lamination 745 and the support sleeve 750. The thrust washer supports 1210 can contact the steel support sleeve 750 at contact areas each side of the steel support sleeve 750. The thrust washer 730 can be disposed concentrically around the thrust washer support 1210 (e.g. with the thrust washer support 1210 disposed radially between the thrust washer 730 and the drive shaft 220), and in some embodiments can be trapped between the steel support sleeve 750 and a portion of the thrust washer support 1210 (e.g. as shown in FIG. 12), creating the axial clearances 1016 and 1017. Clearance 1016 (e.g. the bearing gap) can be configured with the goal of the thrust washers 730 not contacting the bearing bushing assembly 610 during the motor operation (e.g. when rotor assembly 215 is rotating inside the stator assembly 210). In embodiments, the clearance 1017 (e.g. the module gap) can be configured to accommodate the differential thermal expansion of the cage rings 725 and cage bars 720 in the axial direction with respect to the steel lamination stack 740 of the magnetic rotor module 405.

[0068] In embodiments, the concavities may each comprise a shallow, converging wedge shape, for example in which the span of the concavity is significantly greater (e.g. for example 500-10,000; 500-5,000, 5,000-10,000; 1,000-10,000; 1,000-5,000; 3,000-10,000; 3,000-5,000; 5,000-7,000; 7,000-10,000, 500-1,000; 500-3,000; 1,000-3,000, or 3,000-10,000) than its depth and / or with the depth narrowing towards one or more edges. In some embodiments, the concavities may have a curvature / arc with a radius which is orders of magnitude greater than its depth (e.g., arc multiple), for example 500-10,000; 500-5,000, 5,000-10,000; 1,000-10,000; 1,000-5,000; 3,000-10,000; 3,000-5,000; 5,000-7,000; 7,000-10,000, 500-1,000; 500-3,000; 1,000-3,000, or 3,000-10,000 times its depth. For example, the radius of curvature for the concavities may be greater than or approximately 200 mm (e.g. 100-1000 mm) while the depth of the concavities may be approximately 0.01-0.5 mm, 0.05-0.4 mm, 0.05-0.25 mm, 0.05-0.1 mm, 0.1-0.5 mm, or 0.1-0.25 mm.

[0069] Referring to FIG. 15A, the concavity 611 may have an arcuate profile in which an angle between the arcuate profile and the axial face 614 of the bushing 610 (or the axial face 731 of the thrust washer 730) decreases moving towards the center of the concavity. The shape may a segment of a circle, a segment of an oval, a parabola, or an irregular shape, and / or may form a scallop. In some embodiments, the profile is symmetrical, which may have the advantage of allowing the bushing 610 to rotate clockwise or counterclockwise with no change in the hydrodynamic effect of the concavities 611. In some embodiments, the profile may be asymmetrical (for example, similar to half of the concavity shown in FIG. 15A). The groove 612, if formed in the concavity 611, may be formed at the center of the arcuate profile or offset with respect to the center of the arcuate profile. In FIG. 15, the solid line represents the profile of the concavity 611 with the optional groove 612 and the dashed line 612A represents the profile of the concavity 611 without the optional groove 612.

[0070] Referring to FIG. 15B, the concavity may alternatively have a V-shaped profile. That is, a depth of the concavity 611 may increase or decrease in a linear fashion moving from one side of the concavity 611 to the other, or the depth of the concavity 611 may decrease moving from a center of the concavity 611 to an end of the concavity 611. For example, the concavities may each comprise one or more chamfer, having a very shallow angle (e.g. 0.005-0.05 degrees, 0.01-5 degrees, 0.01-0.1 degrees, 0.01-2.5 degrees, 0.1-2.5 degrees, 0.01-1 degrees, 0.1-10 degrees, or 0.05-0.1 degrees). The dashed line shows an embodiment where in the absence of the groove 612 the profile levels out towards the center, but in other embodiments the profile comes together at an angle (e.g., sharp or rounded). In some embodiments, the leveled-out portion could be relatively longer or shorter than what is shown in FIG. 15B. The groove 612 may be formed at the center of the V-shaped profile. The groove 612 is shown in FIG. 15 as having an arcuate profile but in other embodiments, the groove 612 could have a square, triangular, or irregularly shaped profile. An exemplary rectangular embodiment is denoted with reference numeral 612A.

[0071] Referring to FIG. 15C, the concavity 611 may have an actuate profile in which an angle between the arcuate profile and the axial face 614 of the bushing 610 (or the axial face 731 of the thrust washer 730) increases moving towards a center of the concavity 611. In embodiments, such concavities may be similar in shape to the chamfer of FIG. 15B, but with a radius of curvature (e.g. fillet radius) in place of a linear angled surface. The groove 612 may be formed at the center of the actuate profile, at another location within the arcuate profile, or be absent from the concavity 611 altogether. In the embodiment shown in FIG. 15C where there is a groove 612, the groove 612 may start at or be disposed between inflection points of the curve defining the concavity 611. In embodiments where there is no groove 612 in the concavity 611, the profile of the concavity 611 may have a flat portion (e.g., in the middle of the concavity 611) or may have a U-shaped curvature in the middle or at another location on the concavity 611.

[0072] In view of the various profiles shown in FIG. 15, it can be seen that fluid may enter the concavity 611 from one direction, be drawn into the concavity 611, and then be expelled out of the concavity on the other side. When the fluid is expelled, it may be forced into a small gap between the bushing 610 and the thrust washer 730 (e.g. formed by a converging wedge portion of the concavity and / or narrowing of the depth of the concavity, for example with the volume of fluid being forced into a progressively shallower gap) and thus maintain separation of the thrust washer 730 and the bushing 610 while the shaft 220 turns. That is, the fluid dynamics caused by the concavity may repel the bushing 610 from the thrust washer 730 so that they do not touch when the shaft 220 rotates. The configuration / shape of the concavities may be selected to provide the hydrodynamic force for separating the busing 610 and thrust washer 730 due to fluid dynamics, effectively providing a hydrodynamic bearing between the busing 619 and the thrust washer 730. Although the exemplary embodiments of FIG. 15 shows that the concavity 611 and the optionally the groove 612 are formed on the bushing 610 and the thrust washer 730 is flat, in some embodiments, the concavity 611 and optionally the groove 612 are formed on the thrust washer 730 and the bushing 610 is flat. Regardless, the opening / gap formed by the concavities 611 may be disposed between the axial faces of the bushing 610 and the thrust washer 730. In some embodiments, the width of the groove 612 is one quarter or less the width of the concavity 611. In some embodiments, the concavities 611 are equally spaced around the bushing 610 or the thrust washer 730 (e.g., they are spaced apart by a constant interval). In some embodiments, the number of concavities 611 is ten, but any number greater than one is within the scope of the present disclosure (e.g. 2-10, 3-10, 4-10, 6-10, 8-10, 4-8, or 6-8 concavities may be spaced around the bushing 610 or thrust washer 730). In some embodiments, the number of grooves 612 is eight to twelve, but any number greater than one is within the scope of the present disclosure. In some embodiments, the number of grooves 612 may equal the number of concavities 611 (for example, with each concavity 611 having a corresponding groove 612 therein).

[0073] It should be noted that FIGS. 15A-C are not to scale, but purposefully exaggerate the depth of the concavity (e.g. with respect to the radius of curvature) for ease of viewing various elements thereof.

[0074] Referring again to FIGS. 12 and 14, the concavities 611 and the grooves 612 may be formed in the axial face 614 of the bushing 610. Channels 616 may be formed in an outer circumferential surface 617 of the bushing 610 and / or extend from the axial face 614 of the bushing 610 to another axial face 614 of the bushing 610. The channels 616 may be approximately parallel to each other. The concavities 611 and / or the grooves 612 may extend from the inner circumferential surface 618 of the bushing towards the outer circumferential surface 617 of the bushing 610 such that the concavities 611 and / or the grooves 612 span across the entire axial face 614 of the bushing 610. The concavities 611 and / or the grooves 612 may have radial symmetry. In the embodiment of FIG. 14, the grooves 612 may be angularly aligned with the channels 616 and / or the concavities 611 may be angularly aligned with the channels 616. In the embodiment of FIG. 16, the grooves 612 may be angularly offset from the channels 616 and / or the concavities 611 may be angularly offset from the channels 616. In some embodiments, edges of the concavities 611 do not overlap with the channels 616. The location of the concavities 611 can be arbitrarily selected to maximize the axial force.

[0075] In some embodiments, such as the embodiment of FIG. 17, additional grooves 612 may be disposed between the concavities 611 which may also have grooves 612. The grooves 612 disposed between the cavities 611 may be wider and / or deeper than the grooves 612 disposed in the concavities 611. Any suitable combination or arrangement of stand-alone concavities 611, stand-alone grooves 612, and / or grooves 612 formed in concavities 611 is within the scope of the present disclosure.

[0076] Referring to FIGS. 18A and 18B, the axial face 614 of the bushing 610 may be substantially flat (i.e., there may be no concavities 611 nor grooves 612 on the axial face 614 of the bushing 610) in some embodiments. In embodiments, the outer circumferential surface 617 of the bushing 610 may also be unbroken (i.e., there may be no channels 616 formed in the outer circumferential surface 617). Instead, channels 616 may be formed in an outer circumferential surface 732 of the thrust washer 730 (e.g., extending from the axial face 731 of the thrust washer 730 to another axial face 731 of the thrust washer 730). The concavities 611 and the grooves 612 may extend from an inner circumferential surface 733 of the thrust washer 730 towards an outer circumferential surface 732 of the thrust washer 730 such that the concavities 611 and the grooves 612 span across the entire axial surface 731 of the thrust washer 730. Any configuration of concavities 611, grooves 612 and / or channels 616 disclosed herein as being applied to the bushing 610 may also be applied to the thrust washer 730 or the end face of the rotor module 405, case ring 725, spacer ring 1210, or any other suitable element.

[0077] Referring again to FIG. 12, the thrust washer 730 may be concentrically disposed about the drive shaft 220. The journal sleeve 770 may be disposed between the drive shaft 220 and the bushing 610. An outer diameter of the thrust washer 730 may be greater than or equal to an inner diameter of the bushing 610. In some embodiments, the outer diameter of the thrust washer 730 may extend to be adjacent to at least half of the axial face of the bushing 610. In some embodiments, an outer diameter of the thrust washer 730 may be approximately equal to an outer diameter of the bushing 610 or may be greater than the outer diameter of the bushing 610. In some embodiments, the thrust washer 730 may extend radially outward at least as far as the inner diameter of the bushing 610 but no more than the outer diameter of the bushing 610. There may be two thrust washers 730 (i.e., a washer 730 and another washer 730), and the bushing 610 may be disposed between the two thrust washers 730. The length of the bushing 610 may be approximately the same as the length of the inner journal sleeve 770. The bushing 610 and / or the inner journal sleeve 770 may be disposed entirely within a plane defined by an inner axial face 731 of the thrust washer 730 and an inner axial face 731 of the other thrust washer 730. The axial faces of the inner journal sleeve 770 may be proximate to the inner axial faces 731 of the washer 730 and may be coplanar with the axial faces 614 of the bushing 610. The axial faces 614 of the bushing 610 may be approximately parallel to the inner axial faces 731 of the thrust washers 730. Based on this disclosure, persons of skill will understand various embodiments relating to concavities 611 that may be configured to influence flow of lubrication fluid (e.g., oil) between the bushing 610 and the thrust washer 730 to create (e.g. axial) hydrodynamic force against the bushing 610 and the thrust washer 730 when the drive shaft 220 rotates, and this disclosure is not limited to the specific examples illustrated herein.

[0078] In typical ESP motor designs, the bearing assemblies can be allowed to slide within the stator bore. However, to do this they need to overcome friction. In permanent magnet motors, the side forces on the rotor can be especially high, which means the frictional slide forces can also be high. Such a slide force can react axially on to the thrust washer, and typically may be high enough (e.g. sufficiently radially outward) that the thrust washer will deform to form a dish shape. Excessive dishing can lead to contact of the thrust washer with other rotor assembly components and / or damage to the thrust washer and / or other rotor assembly components. In extreme cases, dishing may lead to failure of the thrust washer, another rotor assembly component, the rotor assembly as a whole, and / or the motor.

[0079] Additionally, axial forces can be generated on the thrust washer due to thermal growth, which may contribute to dishing of the thrust washer. In a typical thermal growth scenario (e.g. as discussed above), the bushing assembly can be initially fixed in position (e.g. axially), for example in the motor's stator inside the motor's housing. However, the rotating rotor assembly is typically free to move axially due to the low frictional coefficients of an operating fluid film bearing. For example, axial movement can be created by either the rotor assembly having a different temperature than the stator and / or housing, or by the rotor assembly materials having dissimilar thermal growth coefficients (e.g. CTE) to the stator and / or housing materials. In embodiments, the rotor assembly can be prevented from moving at the head end by a thrust bearing, which can result in thermal growth of the rotor assembly relative to the stator being directed to the base end of the motor (although in other embodiments the thrust bearing could be located at the base end of the motor and / or thermal growth could be towards the head end). As motors can be very long, this thermal growth can be substantial and can typically exceed the bearing gap (e.g. the gap between the thrust washer and the bearing assembly), resulting in contact between the thrust washer and the bearing assembly (e.g. its bushing). If the bearing assembly (e.g. bushing) does not slide, further thermal growth can lead to increasingly high axial forces on the axial faces of the thrust washers (which may cause dishing).

[0080] Thrust washers are typically constructed of polymeric material, for example having an elastic modulus that is significantly lower than the metal or ceramic materials from which the other components of the motor are typically constructed (and thus can be more susceptible to dishing and / or damage). The bearing assembly can also be subjected to a high radial load, for example caused by the gravitational weight of the rotor assembly along with the radial magnetic pull of the rotor modules (e.g. in a PMM rotor) (e.g. and hence the rotor assembly towards the stator.) As a consequence, the axial load required to slide the bearing can also be high (for example with the axial force given by the radial force multiplied by a friction coefficient), and by extension, the thrust washers can be required to carry a significant axial load. In embodiments, application of a high axial load (e.g. radially outward from the base of the thrust washer) to the thrust washer at a force radius well above an exemplary thrust support sleeve's outer diameter can cause the thrust washer to significantly dish (e.g. form a conical form), for example by up to 0.5 mm.

[0081] Additional axial forces on the thrust washer can be generated in rotor assembly embodiments using bearing assemblies and / or thrust washers forming axial concavities (e.g. similar to FIGS. 13-18B). For example, rotor assembly embodiments can include a set of hydrodynamic bearing features (e.g. concavities) on the axial end / face of the bearing assembly and / or thrust washer. These features typically operate with very narrow film thicknesses (e.g. approximately 20 μm) and / or can generate axial forces between the bearing assembly and the adjacent thrust washer. A significant dish of 0.5 mm could severely limit the effectiveness of these features. And even without these features, a significantly dish of the thrust washer could contact the flat axial end of the bearing assembly (e.g. bushing), which may result in significant stress to and / or cutting into the thrust washer. Over time this issue could lead to failure of the thrust washer, and additional loads could result in failed bearings.

[0082] FIG. 19 illustrates schematically an exemplary axial force causing dishing of an exemplary thrust washer 730 of a rotor assembly. In FIG. 19, the axial force acts on the thrust washer 730 at a force radius, which is radially outward from the outer radius (e.g. approximately mid height of the bush face 614) of the exemplary thrust washer support 1210 on which the thrust washer 730 is disposed, resulting in significant dishing (e.g. the dish as shown, which can lead to the thrust washer contacting another component of the rotor assembly). In embodiments, dishing of the thrust washer can include axial deflection of the thrust washer 730 (e.g. the upper portion of the thrust washer) towards another component of the rotor assembly. In some embodiments, dishing can be towards the rotor module, for example.

[0083] To avoid these types of scenarios and ensure good operation of the hydrodynamic bearing features on the axial end of the bearing assembly, thrust washers 730 of exemplary rotor assemblies can be maintained as flat as possible, for example by eliminating or minimizing the dish (e.g. dishing caused by one or more such axial forces on the thrust washer). As discussed in greater detail below, disclosed embodiments can include a thin high-diameter flange (e.g. an axial support flange) to back up the adjacent thrust washer, minimizing dishing of the supported thrust washer and / or addressing issues arising from such axial forces. In some embodiments, exemplary axial support flanges can be configured to ensure that dishing of the thrust washer is less (e.g. typically significantly less) than the film thickness of the hydrodynamic bearing features and / or the bearing or module gap. By way of example, the radial extension, thickness, location, and / or materials of the axial support flange can be selected to adequately support the thrust washer and thereby ensure that the thrust washer does not significantly dish. In some embodiments, to maximize stiffness, the axial support flange can also be mechanically part of a thrust washer support.

[0084] Turning now to the figures for more detailed description, FIG. 20 illustrates a portion of an exemplary rotor assembly 215 embodiment configured to help address excessive dishing of the thrust washers 730, for example by axially supporting the thrust washers 730. In many respects, the rotor assembly 215 of FIG. 20 may be similar to other embodiments described herein, but may also be configured to axially support the thrust washer(s) 730 to minimize dishing. In FIG. 20, an exemplary rotor assembly 215 for an ESP motor comprises a rotor module 405 concentrically disposed on a drive shaft 220; a bearing assembly 410 concentrically disposed about the drive shaft 220 in proximity to the rotor module 405 (e.g. in FIG. 20, the bearing assembly 410 is disposed between two rotor modules 405); a thrust washer 730 concentrically disposed about the drive shaft 220 and axially between the bearing assembly 410 and the rotor module 405 (e.g. in FIG. 20, a thrust washer 730 is disposed on either side of the bearing assembly 410, between the bearing assembly 410 and the rotor module 405 disposed adjacent that side / end of the bearing assembly 410); and an axial support flange 2007 (e.g. high-diameter flange) disposed concentrically about the drive shaft 220 and axially between the thrust washer 730 and the adjacent rotor module 405. The axial support flange 2007 is disposed in proximity to (e.g. backs-up) the thrust washer 730. Typically, the axial support flange 2007 can abut (e.g. axially contact) the thrust washer 730, for example on an axial surface proximal to the rotor module 405 and distal to the bearing bushing assembly 410 (e.g. the thrust washer can be (axially) snug up against the axial support flange). Typically, the rotor module 405 can be configured to rotate with the drive shaft 220, while being operable to slide axially on the drive shaft 220 (e.g. they are keyed together). Typically, an outer diameter of the thrust washer 730 may be greater than or equal to an inner diameter of the bushing assembly 410 (e.g. the outer diameter of the journal sleeve 770) and / or an outer diameter of the thrust washer 730 may be approximately equal to or less than an outer diameter of the bushing assembly 610.

[0085] The bearing assembly 410 of FIG. 20 comprises a journal sleeve 770 concentrically disposed about the drive shaft 220 (e.g. configured to rotate with the drive shaft, while being operable to slide axially with respect to the drive shaft) and a bushing assembly 610 disposed concentrically about the journal sleeve 770, wherein the journal sleeve 770 is free to rotate within (e.g. with respect to) the bushing assembly 610 (e.g. which is typically fixed in place with respect to the stator, with the journal sleeve rotating therein with the drive shaft). In embodiments, rotation of the journal sleeve 770 relative to the bushing assembly 610 can produce hydrodynamic lubrication film. In embodiments, the axial support flange 2007 can be configured to limit axial deflection of the supported thrust washer 730. For example, the axial support flange 2007 can be sufficiently stiff, thick, and / or supportive to limit axial deflection of the thrust washer 730 (e.g. dishing, for example bending deflection towards the adjacent rotor module 405) to less than 100 micron, less than 50 micron, approximately 10-50 micron, less than approximately 10 micron, 2-10 micron, 5-10 micron, or 7-10 micron. In embodiments, the axial support flange 2007 can extend radially outward at least approximately (+ / −4 mm) to an outer diameter 2020 of the journal sleeve 770 (for example, an embodiment of the axial support flange 2007 may extend radially approximately (+ / −4 mm) to the outer diameter of the journal sleeve 770). In embodiments, the axial support flange 2007 can extend radially less than the outer diameter 617 of the bushing assembly 610. Typically, the axial support flange 2007 can comprise steel, and the thrust washer 730 can comprise a polymer (e.g. a flexible / elastic polymer).

[0086] Some rotor modules 405 comprise a lamination stack 740 (e.g. concentrically disposed about the drive shaft 220 and typically configured to rotate with the drive shaft 220), a plurality of cage bars 720 disposed axially within the lamination stack 740 (e.g. within axially extending holes in the lamination stack) and concentrically disposed about the drive shaft 220 (e.g. as a cylindrical cage jointly formed by the cage bars which is concentrically disposed around the drive shaft), a cage ring 725 connected to the plurality of cage bars 720 at each end of the lamination stack 740 and concentrically disposed about the drive shaft 220, and / or end laminations 745 at each end of the lamination stack 740. In some embodiments, the end laminations 745 can be formed of steel, for example steel similar to the lamination stack 740. In some embodiment, the cage rings 725 can be axially outward of the adjacent end lamination 745, for example with the cage ring 725 disposed between the end lamination 745 and the thrust washer 730.

[0087] In some embodiments, the axial support flange 2007 may not extend radially outward beyond the cage bars 720. As shown in FIG. 20, in some embodiments the cage ring 725 can include a flange gap 2012 on its axially exterior surface (e.g. in proximity to the axial support flange 2007), and the flange gap 2012 typically extends radially beyond the axial support flange 2007 (e.g. just beyond). In embodiments having a flange gap 2012 in the cage ring 725, the flange gap 2012 typically does not extend radially outward beyond the cage bars 720 (e.g. the flange gap 2012 may extend radially outward less than the inner diameter of the cage). In embodiments, a module gap 1017 typically extends axially between the thrust washer 730 and the rotor module 405 (e.g. between the thrust washer 730 and the lamination stack 740, cage ring 725, and / or cage bars 720), and the flange gap 2012 can have a width (e.g. extending axially between the axial support flange 2007 and the cage ring 725) approximately equal to the module gap 1017 and / or no less than the module gap 1017. In some embodiments, the rotor module 405 can further comprise one or more magnets concentrically disposed about the drive shaft 220 and axially disposed between the end laminations 745 (e.g. for a PMM motor).

[0088] As shown in FIG. 20, the rotor assembly 215 can further comprise a thrust washer support 1210 (e.g. a bearing spacer) which is disposed concentrically on the drive shaft 220 and axially between the rotor module 405 and the bearing assembly 410. In embodiments, the axial support flange 2007 can be disposed on (e.g. extend radially outward from) the thrust washer support 1210. For example, the axial support flange 2007 can be an integral portion of the thrust washer support 1210. In some embodiments, the thrust washer 730 can be mounted on (e.g. concentrically disposed on) the thrust washer support 1210. For example, the thrust washer 730 can be mounted on a seating surface 2003 of the thrust washer support 1210 (which is typically an integral portion of the thrust washer support). The seating surface 2003, which for example can be configured to receive the thrust washer 730 for seating, with the thrust washer 730 mounted on / concentrically disposed on the seating surface 2003, can be disposed axially between the axial support flange 2007 and the bearing bushing assembly 610 and / or the support sleeve 750. In some embodiments, the thrust washer support 1210 and / or the thrust washer 730 can include an anti-rotation feature 2016 (e.g. configured to limit / restrain / prevent rotation of the thrust washer 730 with respect to the thrust washer support 1210 and / or to rotationally fix the thrust washer 730 to the thrust washer support 1210, for example with the thrust washer configured to rotate with the thrust washer support. For example, the thrust washer 730 can be keyed to the thrust washer support 1210 (e.g. to the seating surface) 2003, as illustrated in FIG. 20A. In embodiments, the thrust washer support seating surface 2003 can comprise one or more key or keyway and the mating / corresponding thrust washer 730 can comprise one or more corresponding keyway or key (e.g. radially oriented) (e.g. jointly forming the anti-rotation feature 2016). In some embodiments, a plurality (e.g. 2-4) key-keyway can be approximately evenly spaced circumferentially about the thrust washer 730 and seating surface 2003.

[0089] In some embodiments, the thrust washer support 1210 can also include a module spacing portion 2004 which is disposed axially between the axial support flange 2007 and the rotor module 405 (e.g. the adjacent end lamination 745). Typically, the module spacing portion 2004 is an integral portion of the thrust washer support 1210. In some embodiments, the cage ring 725 can be disposed radially outward of the module spacing portion 2004. Often, there may be a radial gap therebetween, for example with the cage ring 725 not contacting the module spacing portion 2004. In some embodiments, the module spacing portion 2004 of the thrust washer support 1210 can extend radially beyond the seating surface 2003, but extend radially less than the axial support flange 2007. For example, the axial support flange 2007 may extend radially at least twice as far as the module spacing portion 2004 and / or the module spacing portion 2004 may extend radially less than half of the outer diameter of the journal sleeve 770. In some embodiments, a spring 2030 can be disposed between the module spacing portion 2004 of the thrust washer support 1210 and the rotor module 405 (e.g. the adjacent end lamination 745).

[0090] In the embodiment shown in FIG. 20, a (e.g. bearing) support sleeve 750 can be concentrically disposed on the drive shaft 220, with the support sleeve 750 disposed (e.g. radially) between the bearing assembly 410 (e.g. the journal sleeve 770) and the drive shaft 220. The support sleeve 750 can be configured to provide axial support to the rotor module 410 (e.g. along with the thrust washer support 1210). Typically, the support sleeve 750 is configured to rotate with the drive shaft 220, while being operable to slide axially on the drive shaft 220 (e.g. it is keyed to the drive shaft), and the journal sleeve 770 can be secured to the support sleeve 750 to rotate with the drive shaft 220. For example, the journal sleeve 770 can be secured to the support sleeve 750 by one or more anti-rotation elements 1120 (e.g. helical springs or elastomeric rings). In FIG. 20, the thrust washer support 1210 (e.g. bearing spacer) can be disposed axially between the support sleeve 750 and the rotor module 405, for example with the thrust washer support 1210 (axially) abutting (e.g. contacting) the support sleeve 750 (and typically the adjacent rotor module or a spring disposed therebetween).

[0091] In embodiments, the thrust washer 730 can be mounted on the thrust washer support 1210 such that the thrust washer 730 is not disposed in the axial load path of the rotor stack (e.g. rotor module(s)) and the bearing assembly and / or support sleeve). For example, the thrust washer support 1210 may carry the axial load of the rotor stack, with the thrust washer 730 radially displaced from the axial load by resting atop the thrust washer support 1210 (e.g. the thrust washer does not experience axial load from the rotor module or the support sleeve / bearing assembly). In some embodiments, the thrust washer support 1210 can be configured to rotate with the drive shaft 220, while being operable to slide axially on the drive shaft 220. For example, the thrust washer support 1210 can be keyed to the drive shaft 220. In some embodiments, the thrust washer support 1210 can have a CTE similar to the lamination stack 740 and / or support sleeve 750. And while the journal sleeve 770 of the bearing assembly 410 in FIG. 20 rests atop the support sleeve 750, in some embodiments, the journal sleeve 770 can be concentrically disposed directly on the drive shaft 220 (e.g. and the journal sleeve can be configured to rotate with the drive shaft while being operable to slide axially on the drive shaft).

[0092] As briefly discussed above, FIG. 20A illustrates an exemplary thrust washer 730 mounted on an exemplary thrust washer support 1210 having an axial support flange. FIG. 20B illustrates the example thrust washer support 1210 (shown without a thrust washer mounted thereon), showing the axial support flange 2007. As shown in FIG. 20A, the thrust washer 730 can be keyed to the thrust washer support 1210 (e.g. so that the thrust washer rotates with the thrust washer support). For example, corresponding key and keyway (e.g. anti-rotation feature 2016) can rotationally fix the thrust washer 730 to the thrust washer support 1210. In embodiments, the axial support flange 2007 (e.g. extending from the thrust washer support) can abut the thrust washer 730. In some embodiments, the thrust washer support 1210 can be rotationally fixed to the drive shaft 220 (although typically allowed to slide axially on the drive shaft), for example using a key, such that the thrust washer 730 mounted on the thrust washer support 1210 also rotates with the drive shaft 220.

[0093] By providing axial support (e.g. backing-up) the thrust washer 730 with an adjacent axial support flange 2007, dishing of the thrust washer 730 can be reduced. FIG. 21 illustrates schematically the reduction in dishing of the thrust washer 730 due to an exemplary axial support flange 2007. Typically, the axial support flange 2007 is configured to reduce dishing (e.g. axial deflection) of the thrust washer 730 so that during motor operation the thrust washer 730 does not contact an adjacent component of the rotor assembly (e.g. in FIG. 21 the rotor module). For example, in FIG. 21 dishing (e.g. during normal motor operation) can be no more than 100 micron, no more than 50 micron, approximately 10-50 micron, no more than 10 micron, 2-10 micron, 5-10 micron, or 7-10 micron.

[0094] FIG. 22 illustrates an alternate rotor assembly embodiment 215. In the example of FIG. 22, the thrust washer 730 can be concentrically disposed on the support sleeve 750. For example, the thrust washer 730 can be disposed in proximity to an axial end of the support sleeve 750. A separate thrust washer support 1210 (e.g. without a seating surface) can axially abut the support sleeve 750. Typically, the axial support flange 2007 is disposed at an axial end of the thrust washer support 1210 in proximity to the thrust washer 730 and / or support sleeve 750 (e.g. distal to the rotor module), and the axial support flange 2007 can abut the thrust washer 730. In embodiments, the thrust washer support 1210 can include a module spacing portion 2004 which is disposed axially between the axial support flange 2007 and the rotor module 405 (e.g. the adjacent end lamination). Typically, the module spacing portion 2004 can be configured to provide the module gap 1017 between the axial support flange 2007 and the rotor module 405 (e.g. the adjacent cage ring). In FIG. 22, the module spacing portion 2004 of the thrust washer support 1210 extends radially less than the axial support flange 2007. For example, the axial support flange 2007 can extend radially outward at least twice as far as the module spacing portion 2004 and / or the module spacing portion 2004 can extend radially less than half of the outer diameter of the journal sleeve 770). In embodiments, the module support portion 2004 and the axial support flange 2007 can be integral to the thrust washer support 1210 (e.g. the thrust washer support 1210 is a single, integral element having the module spacing portion 2004 and the axial support flange 2007). In the embodiment of FIG. 22, the cage ring 725 is disposed radially outward of the module spacing portion 2004 (e.g. with a radial gap therebetween). In some embodiments, a spring can be disposed between the module spacing portion 2004 of the thrust support sleeve 1210 and the rotor module 405 (e.g. the adjacent end lamination), for example similar to that shown in FIG. 20.

[0095] In some embodiments, the support sleeve 750 and / or the thrust washer 730 can include an anti-rotation feature 2212 (e.g. configured to limit / restrain / prevent rotation of the thrust washer 730 with respect to the support sleeve 750 and / or to rotationally fix the thrust washer 730 to the support sleeve 750). For example, the thrust washer 730 can be keyed (e.g. radially) to the support sleeve 750, for example with corresponding one or more key and keyway (jointly forming anti-rotation feature 2212) as illustrated in FIG. 22A. In some embodiments, a plurality (e.g. 2-4) of keys and keyways can be approximately evenly spaced circumferentially about the thrust washer 730 and support sleeve 750. While the thrust washer 730 is mounted on the support sleeve 750 in FIG. 22, in some embodiments, the thrust washer 730 can be disposed directly on the drive shaft 220, for example via sliding and / or interference fit (e.g. with a separate thrust support sleeve 1210 axially contacting the thrust washer 730 with its axial support flange 2007, similar to the description above). See for example FIG. 23 for an illustration.

[0096] While the discussion above (e.g. for FIGS. 20, 22, and 23) relates to the interaction between the bearing assembly 410 and an adjacent rotor module 405, it should be clear from the figures that typically there can be a second rotor module 405 disposed adjacent to the bearing assembly 410 opposite the first rotor module 405 (e.g. one rotor module 405 disposed in proximity to each axial end of the bearing assembly 410). For example, embodiments can further comprise: a second (e.g. similar) rotor module, wherein the support sleeve and / or bearing assembly is disposed axially between the two rotor modules (e.g. the first and second rotor modules); a second axial support flange and / or thrust washer support, disposed between the support sleeve / bearing assembly and the second rotor module, wherein the second axial support flange and / or thrust washer support is similar to the first axial support flange and / or thrust washer support; and a second thrust washer concentrically disposed about the drive shaft and axially disposed between the support sleeve / bearing assembly and the second rotor module, wherein the second thrust washer is similar to the first thrust washer. Typically, the second axial support flange axially abuts the second thrust washer and is disposed between the second thrust washer and the second rotor module. In some embodiments, the second thrust washer can be disposed on the seating surface of the second thrust washer support. In some embodiments, the second thrust washer can be disposed on the support sleeve. In some embodiments, the second thrust washer can be disposed directly on the drive shaft. Typically, the second thrust washer and second axial support flange and / or thrust washer support can be disposed / oriented / configured similarly to the first thrust washer and first axial support flange and / or thrust washer support (e.g. with the second rotor module, second axial support flange and / or thrust washer support, and second thrust washer mirroring those on the first / opposite side or end of the support sleeve / bearing assembly). In embodiments, the first and second of similar elements can be similarly configured and / or oriented.

[0097] As previously mentioned, concavities (e.g. scallops) can be formed in an axial face of the bushing assembly 610 (e.g. the bushing of the bushing assembly) or an axial face of the thrust washer 730 (e.g. in embodiments such as illustrated in FIG. 20, FIG. 22, or FIG. 23). For example, the axial face of the bushing assembly 610 can be disposed proximate to the axial face of the thrust washer 730, and the concavities can be configured to influence flow of lubrication fluid between the bushing assembly 610 and the thrust washer 730 to create a hydrodynamic force against the bushing assembly 610 and the thrust washer 730 when the drive shaft rotates. Typically, the hydrodynamic force may prevent contact between the bushing assembly 610 and the thrust washer 730 (e.g. no contact between the axial face of the bushing assembly and the axial face of the thrust washer) when the drive shaft rotates. Such hydrodynamic force can exert (e.g. act as) an axial force on the thrust washer 730 (e.g. of the sort which may cause dishing of the thrust washer, and which can be reduced by the axial support flange 2007). In embodiments, the axial hydrodynamic force may be experienced by the thrust washer 730 even though the thrust washer 730 is disposed out of the axial load path of the rotor stack (e.g. disposed on the thrust washer support 1210 or support sleeve 750). In embodiments, the hydrodynamic force may act to axially push the thrust washer 730 away from the adjacent bearing assembly.

[0098] Referring to FIGS. 1, 12, 14, 20, 22, and / or 23, an exemplary electric submersible pump 106 for pumping fluid in a wellbore 102 may include a centrifugal pump 116; a drive shaft 220 configured to transmit torque to the centrifugal pump 116; a stator 210 configured to drive the drive shaft 220; a journal sleeve 770 concentrically disposed about and rotationally fixed to the drive shaft 220; a bushing 610 concentrically disposed about and configured to rotate with respect to the journal sleeve 770; and a thrust washer 730 encircling the drive shaft 220. The bushing 610 may contact and slide against (e.g. rotate with respect to) the inner journal sleeve 770. The inner journal sleeve 770 may be fixed with respect to the adjacent support sleeve 750, which is fixed with respect to the shaft 220. Oil (or other lubrication fluid) may flow through the bore 221 in the drive shaft 220 and into the oil hole 222. The oil may then enter the gap between the bushing 610 and the thrust washer 730. Concavities 611 may be formed in an axial face 614 of the bushing 610 or an axial face 731 of the thrust washer 730. The axial face 614 of the bushing 610 may be disposed proximate to the axial face 614 of the thrust washer 730 (e.g. with the gap formed by the concavities therebetween). The concavities may be configured to influence flow of lubrication fluid (e.g., oil) between the bushing 610 and the thrust washer 730 to create a hydrodynamic force against the bushing 610 and the thrust washer 730 (e.g. separating the two) when the drive shaft 220 rotates. In other words, the concavities may be configured to influence flow of lubrication fluid (e.g., oil) between the bushing 610 and the thrust washer 730 to create a hydrodynamic film between the bushing 610 and the thrust washer 730 when the drive shaft 220 rotates, which provides the hydrodynamic forces that tend to separate the bushing from the thrust washer (or alternatively, separate the bushing from another component in proximity to the axial face of the bushing). The hydrodynamic film may provide a hydrodynamic bearing effect between the bushing and the thrust washer. The drive shaft 220 may be oriented in the wellbore 102 vertically. A first slot 619 may formed in the outer circumferential surface 617 of the bushing 610 proximate the axial face 614 of the bushing. A second slot 619 may be formed in the outer circumferential surface 617 of the bushing 610 proximate another axial face 614 of the bushing 610. An anti-rotation tab 606 may be secured in a longitudinal slit (e.g., axial slot 715) in the outer circumferential surface 617 of the bushing 610 by a first retention ring 615 disposed in the first slot 619 and a second retention ring 615 disposed in the second slot 619. The anti-rotation tab 606 may be inserted inside a slot in the stator 210.

[0099] Because of the configuration of the rotor bearing assembly 410, and in particular because of the configuration of the concavities 611, life of the rotor bearing assembly 410 may be greatly extended as compared with the conventional art. For example, adding the concavities 611 having the arc radius of 500-10,000; 500-5,000; 5,000-10,000, 1,000-10,000; 1,000-5,000; 3,000-5,000; 3,000-10,000, 5,000-7,000; or 7,000-10,000 times the depth can extend the life of the rotor bearing assembly 410 significantly, for example one thousand-fold. Depending on the application (for example, the operating speed, operating temperature, oil grade, and dimension of the parts), the hydrostatic force generated by the concavities 611 may be in the range of 5 to 1,000 Newtons, or alternately 5-500 Newtons, 5-100 Newtons, 50-1,000 Newtons, 50-500 Newtons, 50-100 Newtons, 100-1,000 Newtons, 100-500 Newtons, 500-1,000 Newtons, 500-750 Newtons, 750-1,000 Newtons, or more. The improved longevity as compared with the conventional art may allow the ESP to pump fluid in the well with reduced downtime, thus improving efficiency and reducing costs in extracting oil.

[0100] Exemplary method embodiments for assembling a rotor assembly (e.g. for an ESP motor) can comprise: disposing a bearing assembly concentrically about a drive shaft; disposing a rotor module concentrically on the drive shaft adjacent to the bearing assembly, wherein the rotor module is configured to rotate with the drive shaft while being operable to slide axially on the drive shaft; disposing a thrust washer concentrically about the drive shaft and axially between the rotor module and the bearing assembly; and disposing an axial support flange concentrically about the drive shaft and axially between the thrust washer and the rotor module, wherein the axial support flange axially abuts / contacts the thrust washer. Some embodiments can further comprise providing a thrust washer, wherein an outer diameter of the thrust washer is greater than or equal to an inner diameter of the bushing assembly (e.g. the outer diameter of the journal sleeve), and / or wherein an outer diameter of the thrust washer is approximately equal to or less than an outer diameter of the bushing assembly. Some embodiments can further comprise providing the axial support flange, wherein the axial support flange is sufficiently stiff / thick / supportive (e.g. is configured) to limit axial deflection of the thrust washer (e.g. dishing, for example bending deflection towards the adjacent rotor module) to less than 100 micron, approximately 10-100 micron, less than 50 micron, approximately 10-50 micron, less than approximately 10 micron, 2-10 micron, 5-10 micron, or 7-10 micron. Limiting axial deflection / dishing in this manner can be beneficial for the operation of concavities to generate hydrostatic force (as discussed above).

[0101] Some method embodiments can further comprise disposing a thrust washer support concentrically on the drive shaft and axially between the bearing assembly and the rotor module, wherein the thrust washer support is configured to rotate with the drive shaft while being operable to slide axially on the drive shaft, and the axial support flange extends radially outward from the thrust washer support. Some embodiments (e.g. relating to FIG. 20) can further comprise providing a thrust washer support having a seating surface extending from the axial support flange axially towards the bearing assembly and a module spacing portion extending axially from the axial support flange towards the rotor module (e.g. end lamination), and wherein disposing the thrust washer comprises disposing the thrust washer onto the seating surface. In some embodiments, disposing the thrust washer on the seating surface can comprise rotationally fixing (e.g. keying) the thrust washer to the seating surface of the thrust washer support. Some embodiments can further comprise providing the rotor module, wherein the rotor module comprises a cage ring adjacent to the thrust washer and / or axial support flange, and the cage ring comprises a flange gap. Some method embodiments can further comprise disposing a support sleeve concentrically on the drive shaft, wherein the support sleeve is configured to rotate with the drive shaft while being operable to slide axially on the drive shaft, and the bearing assembly (e.g. journal sleeve) is concentrically disposed on the support sleeve. In some embodiments the thrust washer support can axially abut the support sleeve.

[0102] In some embodiments (e.g. relating to FIG. 22), disposing the thrust washer can comprise concentrically disposing the thrust washer on the support sleeve, the thrust washer support can be disposed between the support sleeve and the rotor module (e.g. abuts the support sleeve and / or the rotor module), and the axial support flange can be disposed at an axial end of the thrust washer support in proximity to the thrust washer and / or support sleeve. In some embodiments, disposing the thrust washer on the support sleeve can comprise rotationally fixing (e.g. keying) the thrust washer to the support sleeve. Some method embodiments can further comprise providing the thrust washer support, wherein the thrust washer support comprises a module spacer portion extending axial from the axial support flange towards the rotor module / end lamination.

[0103] Some method embodiments can further comprise providing the thrust washer and the bearing assembly, wherein the bearing assembly comprises a bushing, and wherein concavities (e.g. scallops) can be formed in (e.g. be disposed on) an axial face of the bushing or an axial face of the thrust washer, wherein the axial face of the bushing can be disposed proximate to the axial face of the thrust washer, and wherein the concavities can be configured to influence flow of lubrication fluid between the bushing and the thrust washer to create a hydrodynamic force (e.g. axial) against the bushing and the thrust washer when the drive shaft rotates. Some embodiments can include disposing a spring axially between the thrust washer support and an end lamination of the rotor module. In embodiments, the methods can relate to any rotor assembly embodiments described herein. Persons of skill will understand that one or more of the disclosed method embodiments can relate to one or more of the disclosed rotor assembly embodiments.

[0104] Additionally, an exemplary method of using a rotor assembly (e.g. for an ESP motor) can comprise: assembling the rotor assembly (e.g. at a wellsite) using any of the disclosed method embodiments; assembling the ESP motor with the rotor assembly therein; assembling an ESP assembly comprising the ESP motor coupled to an ESP pump; inserting / placing the ESP assembly downhole in a wellbore; and / or pumping formation fluids from the wellbore to the surface using the ESP assembly. In embodiments, the rotor assembly can comprise any one of the disclosed rotor assembly embodiments.Additional Disclosure

[0105] The following are non-limiting, specific embodiments in accordance with the present disclosure:

[0106] In a first embodiment, a rotor assembly for an ESP motor comprises: a rotor module concentrically disposed on a drive shaft, wherein the rotor module is configured to rotate with the drive shaft, while being operable to slide axially on the drive shaft; a bearing assembly concentrically disposed about the drive shaft in proximity to the rotor module; a thrust washer concentrically disposed about the drive shaft and axially between the bearing assembly and the rotor module; and an axial support flange (e.g. a high-diameter flange) disposed concentrically about the drive shaft and axially between the thrust washer and the rotor module, wherein the axial support flange axially is adjacent to (e.g. abuts) the thrust washer; wherein the bearing assembly comprises a journal sleeve concentrically disposed about the drive shaft and a bushing assembly disposed concentrically about the journal sleeve, wherein the journal sleeve is free to rotate within the bushing assembly.

[0107] A second embodiment can include the rotor assembly of the first embodiment, wherein the axial support flange is configured to limit axial deflection of the thrust washer to less than 100 micron, 10-100 micron, less than 50 micron, 10-50 micron, or less than 10 micron (e.g. 2-10 micron).

[0108] A third embodiment can include the rotor assembly of the first or second embodiment, wherein the journal sleeve comprises an outer diameter, and the axial support flange extends radially outward at least approximately to the outer diameter of the journal sleeve (e.g. + / −5 mm, 4 mm, 3 mm, 2 mm, or 1 mm); and wherein the bushing assembly comprises an outer diameter, and the axial support flange extends radially outward no more than (e.g. less than) the outer diameter of the bushing assembly and / or no more than the outer diameter of the thrust washer.

[0109] A fourth embodiment can include the rotor module of any one of the first to third embodiments, wherein: the rotor module comprises: a lamination stack concentrically disposed about the drive shaft and configured to rotate with the drive shaft, a plurality of cage bars disposed axially within the lamination stack and concentrically disposed about the drive shaft, a cage ring connected to the plurality of cage bars at each end of the lamination stack and concentrically disposed about the drive shaft, and / or end laminations at each end of the lamination stack; and / or the axial support flange does not extend radially outward as far as the cage bars (e.g. the cage) and / or the cage ring outer diameter.

[0110] A fifth embodiment can include the rotor module of the fourth embodiment, wherein the cage ring comprises a flange gap on an axially exterior surface, and the flange gap extends radially outward beyond the axial support flange. In some embodiments, the flange gap does not extend radially outward as far as the cage bars (e.g. the cage) and / or the cage ring outer diameter. In some embodiments, the flange gap extends radially approximately the same amount as the axial support flange (e.g. from 0-4 mm beyond the axial support flange).

[0111] A sixth embodiment can include the rotor module of any one of the first to fifth embodiments, further comprising a thrust washer support which is disposed concentrically on the drive shaft and axially between the rotor module and the bearing assembly, wherein the axial support flange extends radially outward from the thrust washer support. In some embodiments, the thrust washer support can be rotationally fixed to the drive shaft (while typically being able to slide axially thereon).

[0112] A seventh embodiment can include the rotor module of the sixth embodiment, wherein the thrust washer support comprises a seating surface which extends axially from the axial support flange towards the bearing bushing assembly, and the thrust washer is concentrically disposed on the seating surface. In some embodiments, the thrust washer can be rotationally fixed to the thrust washer support seating surface (e.g. by an ani-rotation feature).

[0113] An eighth embodiment can include the rotor module of the seventh embodiment, wherein the thrust washer support further comprises a module spacing portion which extends axially from the axial support flange towards the rotor module, and wherein the module spacing portion of the thrust washer support extends radially beyond the seating surface, but extends radially less than the axial support flange. In some embodiments, the seating surface, module spacing portion and axial support flange are all integral to the thrust washer support.

[0114] A ninth embodiment can include the rotor module of any one of the seventh to eighth embodiments, further comprising a support sleeve concentrically disposed on the drive shaft, wherein the support sleeve is disposed radially between the bearing assembly and the drive shaft, and wherein the thrust washer support is disposed axially between the support sleeve and the rotor module. In embodiments, the thrust washer support abuts the support sleeve and / or the thrust washer support and the support sleeve axially support the rotor module.

[0115] A tenth embodiment can include the rotor module of the sixth embodiment, further comprising a support sleeve concentrically disposed on the drive shaft, wherein: the support sleeve is disposed radially between the bearing assembly and the drive shaft; the thrust washer support is disposed axially between the support sleeve and the rotor module; the thrust washer is concentrically disposed on the support sleeve (e.g. at an axial end); the thrust washer support axially abuts the support sleeve; and the axial support flange is disposed at an axial end of the thrust washer support in proximity to the support sleeve and / or abuts / contacts the thrust washer. In some embodiments, the thrust washer can be rotationally fixed to the support sleeve (e.g. by an anti-rotation feature).

[0116] An eleventh embodiment can include the rotor module of any one of the first to tenth embodiments, wherein concavities (e.g. scallops) are formed in an axial face of the bushing assembly or an axial face of the thrust washer, wherein the axial face of the bushing assembly is disposed proximate to the axial face of the thrust washer, and wherein the concavities are configured to influence flow of lubrication fluid between the bushing assembly and the thrust washer to create a hydrodynamic force (e.g. axially) against the bushing assembly and the thrust washer when the drive shaft rotates. Any one of the disclosed rotor bearings configured to create hydrodynamic force (e.g. using concavities) can be used in the rotor module of any one of the first to eleventh embodiments.

[0117] In a twelfth embodiment, a method for assembling a rotor assembly for an ESP motor comprises: disposing a bearing assembly concentrically about a drive shaft; disposing a rotor module concentrically on the drive shaft adjacent to the bearing assembly, wherein the rotor module is configured to rotate with the drive shaft while being operable to slide axially on the drive shaft; disposing a thrust washer concentrically about the drive shaft and axially between the rotor module and the bearing assembly; and disposing an axial support flange concentrically about the drive shaft and axially between the thrust washer and the rotor module, wherein the axial support flange axially contacts (e.g. abuts) the thrust washer.

[0118] A thirteenth embodiment can include the method of the twelfth embodiment, further comprising: providing the bearing assembly, wherein the bearing assembly has a journal sleeve and a bushing assembly; providing a thrust washer, wherein an outer diameter of the thrust washer is greater than an inner diameter of the bushing assembly (e.g. an outer diameter of the journal sleeve) and an outer diameter of the thrust washer is less than an outer diameter of the bushing assembly; and providing the axial support flange, wherein the axial support flange is configured to limit axial dishing of the thrust washer to less than 50 micron, 10-50 micron, or less than 10 micron. For example, the axial support flange may extend radially at least approximately to the outer diameter of the journal sleeve, may comprise steel, and / or may have sufficient thickness to provide the necessary stiffness / support.

[0119] A fourteenth embodiment can include the method of the thirteenth embodiment, wherein: the journal sleeve of the bearing assembly comprises an outer diameter, and the axial support flange extends radially at least approximately to the outer diameter of the journal sleeve; and the axial support flange extends radially less than the outer diameter of the bushing assembly.

[0120] A fifteenth embodiment can include the method of any one of the twelfth to fourteenth embodiments, further comprising disposing a thrust washer support concentrically on the drive shaft and axially between the bearing assembly and the rotor module, and wherein the axial support flange extends radially outward from the thrust washer support. In some embodiments, the thrust washer support can be configured to rotate with the drive shaft while being operable to slide axially on the drive shaft.

[0121] A sixteenth embodiment can include the method of the fifteenth embodiment, further comprising providing a thrust washer support, wherein the thrust washer support has a seating surface extending from the axial support flange axially towards the bearing assembly and a module spacing portion extending axially from the axial support flange towards the rotor module, wherein disposing the thrust washer concentrically about the drive shaft comprises disposing the thrust washer onto the seating surface and / or rotationally fixing the thrust washer to the seating surface of the thrust support sleeve. Some embodiments can also comprise disposing a support sleeve concentrically on the drive shaft, wherein the thrust washer support is axially disposed between the support sleeve and the rotor module (e.g. abutting the support sleeve).

[0122] A seventeenth embodiment can include the method of the fifteenth embodiment, further comprising disposing a support sleeve concentrically on the drive shaft, wherein: the support sleeve is configured to rotate with the drive shaft while being operable to slide axially on the drive shaft, and the bearing assembly is concentrically disposed on the support sleeve; disposing the thrust washer concentrically about the drive shaft comprises concentrically disposing the thrust washer on the support sleeve; the thrust washer support is axially disposed between the support sleeve and the rotor module; the axial support flange is disposed at an axial end of the thrust washer support in proximity to the support sleeve; and / or disposing the thrust washer on the support sleeve comprises rotationally fixing the thrust washer to the support sleeve.

[0123] An eighteenth embodiment can include the method of any one of the twelfth to seventeenth embodiments, further comprising providing the thrust washer and the bearing assembly, wherein the bearing assembly comprises a bushing, and wherein concavities are formed in an axial face of the bushing or an axial face of the thrust washer, wherein the axial face of the bushing is disposed proximate to the axial face of the thrust washer, and wherein the concavities are configured to influence flow of lubrication fluid between the bushing and the thrust washer to create a hydrodynamic force (e.g. axially) against the bushing and the thrust washer when the drive shaft rotates.

[0124] A nineteenth embodiment can include the method of any one of the twelfth to eighteenth embodiments, wherein the rotor assembly comprises any one of the disclosed embodiments (e.g. any one of the first to eleventh embodiments).

[0125] In a twentieth embodiment, a method of using a rotor assembly (e.g. for an ESP motor) comprises: assembling the rotor assembly using any one of the twelfth to nineteenth embodiments; assembling the ESP motor with the rotor assembly therein; assembling an ESP assembly comprising the ESP motor coupled to an ESP pump; disposing / inserting the ESP assembly downhole in a wellbore; and / or pumping formation fluids from the wellbore to the surface using the ESP assembly.

[0126] A twenty-first embodiment can include the method of the twentieth embodiment, wherein the rotor assembly comprises any one of the disclosed embodiments (e.g. any one of the first to eleventh embodiments).

[0127] While embodiments have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of this disclosure. The embodiments described herein are exemplary only and are not intended to be limiting. Many variations and modifications of the embodiments disclosed herein are possible and are within the scope of this disclosure. For example, the various elements or components may be combined or integrated in another system or certain features may be omitted or not implemented. Also, techniques, systems, subsystems, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other techniques, systems, subsystems, or methods without departing from the scope of this disclosure. Other items shown or discussed as directly coupled or connected or communicating with each other may be indirectly coupled, connected, or communicated with. Method or process steps set forth may be performed in a different order. The use of terms, such as “first,”“second,”“third” or “fourth” to describe various processes or structures is only used as a shorthand reference to such steps / structures and does not necessarily imply that such steps / structures are performed / formed in that ordered sequence (unless such requirement is clearly stated explicitly in the specification).

[0128] Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example, whenever a numerical range with a lower limit, Rl, and an upper limit, Ru, is disclosed, any number falling within the range is specifically disclosed. In particular, the following numbers within the range are specifically disclosed: R=Rl+k*(Ru−Rl), wherein k is a variable ranging from 1 percent to 100 percent with a 1 percent increment, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent, . . . 50 percent, 51 percent, 52 percent, . . . , 95 percent, 96 percent, 97 percent, 98 percent, 99 percent, or 100 percent. Moreover, any numerical range defined by two R numbers as defined in the above is also specifically disclosed. Language of degree used herein, such as “approximately,”“about,”“generally,” and “substantially,” represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the language of degree may mean a range of values as understood by a person of skill or, otherwise, an amount that is + / −10%.

[0129] Use of broader terms such as comprises, includes, having, etc. should be understood to provide support for narrower terms such as consisting of, consisting essentially of, comprised substantially of, etc. When a feature is described as “optional,” both embodiments with this feature and embodiments without this feature are disclosed. Similarly, the present disclosure contemplates embodiments where this “optional” feature is required and embodiments where this feature is specifically excluded. The use of the terms such as “high-pressure” and “low-pressure” is intended to only be descriptive of the component and their position within the systems disclosed herein. That is, the use of such terms should not be understood to imply that there is a specific operating pressure or pressure rating for such components. For example, the term “high-pressure” describing a manifold should be understood to refer to a manifold that receives pressurized fluid that has been discharged from a pump irrespective of the actual pressure of the fluid as it leaves the pump or enters the manifold. Similarly, the term “low-pressure” describing a manifold should be understood to refer to a manifold that receives fluid and supplies that fluid to the suction side of the pump irrespective of the actual pressure of the fluid within the low-pressure manifold.

[0130] Accordingly, the scope of protection is not limited by the description set out above but is only limited by the claims which follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated into the specification as embodiments of the present disclosure. Thus, the claims are a further description and are an addition to the embodiments of the present disclosure. The discussion of a reference herein is not an admission that it is prior art, especially any reference that can have a publication date after the priority date of this application. The disclosures of all patents, patent applications, and publications cited herein are hereby incorporated by reference, to the extent that they provide exemplary, procedural, or other details supplementary to those set forth herein.

[0131] Use of the phrase “at least one of” preceding a list with the conjunction “and” should not be treated as an exclusive list and should not be construed as a list of categories with one item from each category, unless specifically stated otherwise. A clause that recites “at least one of A, B, and C” can be infringed with only one of the listed items, multiple of the listed items, and one or more of the items in the list and another item not listed.

[0132] As used herein, the term “or” is inclusive unless otherwise explicitly noted. Thus, the phrase “at least one of A, B, or C” is satisfied by any element from the set {A, B, C} or any combination thereof, including multiples of any element.

[0133] As used herein, the term “and / or” includes any combination of the elements associated with the “and / or” term. Thus, the phrase “A, B, and / or C” includes any of A alone, B alone, C alone, A and B together, B and C together, A and C together, or A, B, and C together.

Claims

1. A rotor assembly for an ESP motor comprises:a rotor module concentrically disposed on a drive shaft, wherein the rotor module is configured to rotate with the drive shaft, while being operable to slide axially on the drive shaft;a bearing assembly concentrically disposed about the drive shaft in proximity to the rotor module;a thrust washer concentrically disposed about the drive shaft and axially between the bearing assembly and the rotor module; andan axial support flange disposed concentrically about the drive shaft and axially between the thrust washer and the rotor module, wherein the axial support flange axially abuts the thrust washer;wherein the bearing assembly comprises a journal sleeve concentrically disposed about the drive shaft and a bushing assembly disposed concentrically about the journal sleeve, wherein the journal sleeve is free to rotate within the bushing assembly.

2. The rotor assembly of claim 1, wherein the axial support flange is configured to limit axial dishing of the thrust washer to less than 100 micron.

3. The rotor assembly of claim 1, wherein the journal sleeve comprises an outer diameter, and the axial support flange extends radially outward at least approximately to the outer diameter of the journal sleeve; and wherein the bushing assembly comprises an outer diameter, and the axial support flange extends radially outward less than the outer diameter of the bushing assembly.

4. The rotor assembly of claim 1, wherein:the rotor module comprises:a lamination stack concentrically disposed about the drive shaft and configured to rotate with the drive shaft,a plurality of cage bars disposed axially within the lamination stack and concentrically disposed about the drive shaft, anda cage ring connected to the plurality of cage bars at each end of the lamination stack and concentrically disposed about the drive shaft; andthe axial support flange does not extend radially outward as far as the cage bars.

5. The rotor assembly of claim 4, wherein the cage ring comprises a flange gap on an axially exterior surface, and the flange gap extends radially outward beyond the axial support flange.

6. The rotor assembly of claim 1, further comprising a thrust washer support which is disposed concentrically on the drive shaft and axially between the rotor module and the bearing assembly, wherein the axial support flange extends radially outward from the thrust washer support.

7. The rotor assembly of claim 6, wherein the thrust washer support comprises a seating surface which extends axially from the axial support flange towards the bearing bushing assembly, and the thrust washer is concentrically disposed on the seating surface.

8. The rotor assembly of claim 7, wherein the thrust washer support further comprises a module spacing portion which extends axially from the axial support flange towards the rotor module, and wherein the module spacing portion of the thrust washer support extends radially beyond the seating surface, but extends radially less than the axial support flange.

9. The rotor assembly of claim 7, further comprising a support sleeve concentrically disposed on the drive shaft, wherein the support sleeve is disposed radially between the bearing assembly and the drive shaft, and wherein the thrust washer support is disposed axially between the support sleeve and the rotor module.

10. The rotor assembly of claim 6, further comprising a support sleeve concentrically disposed on the drive shaft, wherein:the support sleeve is disposed radially between the bearing assembly and the drive shaft;the thrust washer support is disposed axially between the support sleeve and the rotor module;the thrust washer is concentrically disposed on the support sleeve;the thrust washer support axially abuts the support sleeve; andthe axial support flange is disposed at an axial end of the thrust washer support in proximity to the support sleeve.

11. The rotor assembly of claim 1, wherein concavities are formed in an axial face of the bushing assembly or an axial face of the thrust washer, wherein the axial face of the bushing assembly is disposed proximate to the axial face of the thrust washer, and wherein the concavities are configured to influence flow of lubrication fluid between the bushing assembly and the thrust washer to create a hydrodynamic force against the bushing assembly and the thrust washer when the drive shaft rotates.

12. A method for assembling a rotor assembly for an ESP motor comprising:disposing a bearing assembly concentrically about a drive shaft;disposing a rotor module concentrically on the drive shaft adjacent to the bearing assembly, wherein the rotor module is configured to rotate with the drive shaft while being operable to slide axially on the drive shaft;disposing a thrust washer concentrically about the drive shaft and axially between the rotor module and the bearing assembly;disposing an axial support flange concentrically about the drive shaft and axially between the thrust washer and the rotor module, wherein the axial support flange axially contacts the thrust washer.

13. The method of claim 12, further comprising:providing a bearing assembly, wherein the bearing assembly has a journal sleeve and a bushing assembly;providing a thrust washer, wherein an outer diameter of the thrust washer is greater than an inner diameter of the bushing assembly and an outer diameter of the thrust washer is less than an outer diameter of the bushing assembly; andproviding the axial support flange, wherein the axial support flange is configured to limit axial dishing of the thrust washer to less than 100 micron.

14. The method of claim 13, wherein:the journal sleeve of the bearing assembly comprises an outer diameter, and the axial support flange extends radially at least approximately to the outer diameter of the journal sleeve; andthe axial support flange extends radially less than the outer diameter of the bushing assembly.

15. The method of claim 12, further comprising disposing a thrust washer support concentrically on the drive shaft and axially between the bearing assembly and the rotor module, wherein the thrust washer support is configured to rotate with the drive shaft while being operable to slide axially on the drive shaft, and the axial support flange extends radially outward from the thrust washer support.

16. The method of claim 15, further comprising providing the thrust washer support, wherein the thrust washer support has a seating surface extending from the axial support flange axially towards the bearing assembly and a module spacing portion extending axially from the axial support flange towards the rotor module, wherein disposing the thrust washer concentrically about the drive shaft comprises disposing the thrust washer onto the seating surface and rotationally fixing the thrust washer to the seating surface.

17. The method of claim 15, further comprising disposing a support sleeve concentrically on the drive shaft, wherein:the support sleeve is configured to rotate with the drive shaft while being operable to slide axially on the drive shaft, and the bearing assembly is concentrically disposed on the support sleeve;disposing the thrust washer concentrically about the drive shaft comprises concentrically disposing the thrust washer on the support sleeve;the thrust washer support is axially disposed between the support sleeve and the rotor module;the axial support flange is disposed at an axial end of the thrust washer support in proximity to the support sleeve; anddisposing the thrust washer on the support sleeve comprises rotationally fixing the thrust washer to the support sleeve.

18. The method of claim 12, further comprising providing the thrust washer and the bearing assembly, wherein the bearing assembly comprises a bushing, and wherein concavities are formed in an axial face of the bushing or an axial face of the thrust washer, wherein the axial face of the bushing is disposed proximate to the axial face of the thrust washer, and wherein the concavities are configured to influence flow of lubrication fluid between the bushing and the thrust washer to create a hydrodynamic force against the bushing and the thrust washer when the drive shaft rotates.

19. An ESP motor comprising the rotor assembly of claim 1.

20. A method of using a rotor assembly for an ESP motor comprises:assembling the rotor assembly using the method of claim 12;assembling the ESP motor with the rotor assembly therein;assembling an ESP assembly comprising the ESP motor coupled to an ESP pump;inserting the ESP assembly downhole in a wellbore; andpumping formation fluids from the wellbore to the surface using the ESP assembly.

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