Patent Description:
The present disclosure relates to tools having polycrystalline diamond radial bearings, systems including the same, and methods of making and using the same.

Radial bearings are used in tools, machines, and components to bear load. One application of radial bearings is in motors, including drilling motors. When drilling a wellbore, a drill bit is sometimes rotated via a drilling motor, which may be coupled with the drill bit via a drive shaft extending from the motor, through a bearing housing, and to the drill bit. Such couplings typically include bearings positioned between the bearing housing and the drive shaft to allow rotation of the drive shaft while the bearing housing remains generally stationary within the wellbore or rotates with the drill string.

When polycrystalline diamond elements are used as radial bearings in drilling motors, typically the spacing between adjacent polycrystalline diamond elements is minimized in order to avoid edge contact between the engagement surface of the polycrystalline diamond elements and the opposing engagement surface. Minimizing the spacing between adjacent bearing elements reduces the space on the drill string available for sensors, actuators, or other discrete downhole components.

Also, when polycrystalline diamond elements are used as radial bearings in drilling tools, typically both the engagement surface and the opposing engagement surface are composed of polycrystalline diamond. This is, at least in part, because thermally stable polycrystalline diamond (TSP), either supported or unsupported by tungsten carbide, and polycrystalline diamond compact (PDC or PCD) have been considered as contraindicated for use in the machining of diamond reactive materials. Diamond reactive materials include ferrous metals, and other metals, metal alloys, composites, hardfacings, coatings, or platings that contain more than trace amounts of diamond catalyst or solvent elements including cobalt, nickel, ruthenium, rhodium, palladium, chromium, manganese, copper, titanium, or tantalum. Further, this prior contraindication of the use of polycrystalline diamond extends to so called "superalloys", including iron-based, cobalt-based and nickel-based superalloys containing more than trace amounts of diamond catalyst or solvent elements. The surface speeds typically used in machining of such materials typically ranges from about <NUM>/s to about <NUM>/s. Although these surface speeds are not particularly high, the load and attendant temperature generated, such as at a cutting tip, often exceeds the graphitization temperature of diamond (i.e., about <NUM>), which can, in the presence of diamond catalyst or solvent elements, lead to rapid wear and failure of components. Without being bound by theory, the specific failure mechanism is believed to result from the chemical interaction of the carbon bearing diamond with the carbon attracting material that is being machined. An exemplary reference concerning the contraindication of polycrystalline diamond for diamond catalyst or solvent containing metal or alloy machining is <CIT>. The contraindication of polycrystalline diamond for machining diamond catalyst or diamond solvent containing materials has long caused the avoidance of the use of polycrystalline diamond in all contacting applications with such materials.

Polycrystalline diamond radial bearings have been developed that have polycrystalline diamond bearing surfaces that mate with non-ferrous superhard materials or, much more commonly, with tightly-matched complementary polycrystalline diamond surfaces. As used herein, a "superhard material" is a material that is at least as hard as tungsten carbide (e.g., cemented tungsten carbide or tungsten carbide tiles). An exemplary reference concerning polycrystalline diamond radial bearings, either in contact with superhard materials or with matching polycrystalline diamond, is <CIT> As would be understood by one skilled in the art, hardness may be determined using the Vickers hardness test, which may be performed, for example, in accordance with ASTM E92-<NUM>.

So called high-performance polycrystalline diamond bearings are designed particularly for harsh environments, such as downhole drilling and pumping environments or wind turbine energy units, and utilize sliding, mated, overlapping polycrystalline diamond elements. This requires a large number of polycrystalline diamond elements, each shaped with an exacting outer profile. For example, rotor mounted polycrystalline diamond elements are shaped with a convex outer profile substantially matched to an outer diameter of the rotor. Stator polycrystalline diamond elements are shaped with a concave outer profile substantially matched to an inner diameter of the stator. This shaping of the polycrystalline diamond elements requires exacting precision and is expensive, requiring, for example, cutting with electrical discharge machining (EDM), lasers, or diamond grinding. The polycrystalline diamond elements must then be mounted in precise locations, at precise alignments and at precisely prescribed heights or exposures to ensure mated sliding engagement. The goal in such components is full-face contact of the polycrystalline diamond elements as bearing areas. Thus, the processes used to prepare such polycrystalline diamond elements are expensive and time consuming, with significant opportunities for variance resulting in scrapped parts. Failures in alignment and/or exposure are likely to produce so called "edge clashing" as the polycrystalline diamond elements rotate against each other producing fractured elements and ultimately resulting in bearing failure.

Less expensive radial bearings utilizing polycrystalline diamond have been proposed where a nearly full circumferential array of contoured polycrystalline diamond elements are mounted on a rotor with superhard material mounted on the stator. Although this approach requires fewer polycrystalline diamond elements than the previously described approaches, it still requires contouring of the rotor mounted elements. In addition, such so called superhard materials tend to be more brittle and prone to impact damage than the diamond reactive materials disclosed herein.

Additional significant references that inform the background of the technology of this application are from the <NPL>. These references report on the dynamic friction polishing of PDC faces utilizing dry sliding contact under load with a carbon attractive steel disk. Key findings in these references indicate that polishing rate is more sensitive to sliding rate than load and that the rate of thermo-chemical reaction between the steel disk and the diamond surface reduces significantly as the surface finish of the diamond surface improves. It is indicated that the thermo-chemical reaction between the steel disk and the PDC face does not occur at sliding speeds below <NUM>/s at a pressure of 27MPa. Copper and titanium were not typically listed in the early General Electric documentation on diamond synthesis but have been added later. Relevant references include "<NPL> and "<NPL>.

<CIT> discloses bearing apparatuses including a bearing assembly having a continuous superhard bearing element including a continuous superhard bearing surface and a tilting pad bearing assembly. The disclosed bearing apparatuses may be employed in pumps, turbines or other mechanical systems. In an embodiment, the bearing apparatus includes a first and second bearing assembly. The first bearing assembly includes a first support ring and a plurality of tilting pads. Each tilting pad is tilted and/or tiltably secured relative to the first support ring. The second bearing assembly includes a continuous superhard bearing element. The continuous superhard bearing element includes a continuous superhard bearing surface facing the plurality of tilting pads and exhibits a maximum lateral width greater than about <NUM> inches (<NUM>).

According to a first aspect of the present invention, there is provided a downhole tool for use in a downhole drill string, the downhole tool comprising: a drive shaftmovably coupled within a bearing housing, wherein the drive shaft has a first end and a second end; a rotor coupled with the second end of the drive shaft; a stator coupled with the rotor; and a bearing assembly interfacing engagement between the drive shaft and the bearing housing, the bearing assembly comprising: a plurality of spaced-apart polycrystalline diamond elements, wherein each polycrystalline diamond elements has an engagement surface; and an opposing engagement surface comprising a metal, the metal comprising at least <NUM> wt. % of a diamond catalyst or diamond solvent based on a total weight of the metal, wherein the opposing engagement surface is movably engaged with each of the engagement surfaces; wherein the plurality of polycrystalline diamond elements are coupled with the drive shaft and the opposing engagement surface is a surface on the bearing housing, or wherein the plurality of polycrystalline diamond elements are coupled with the bearing housing and the opposing engagement surface is a surface on the drive shaft.

According to a second aspect of the present invention, there is provided a method of bearing radial and thrust load in a drill string bearing assembly, the method comprising: coupling a drive shaft within a bearing housing, the drive shaft having a first end and a second end, wherein coupling the drive shaft within the bearing housing includes interfacing engagement between the drive shaft and the bearing housing with a bearing assembly, the bearing assembly comprising: a plurality of polycrystalline diamond elements, wherein each polycrystalline diamond elements has an engagement surface; and an opposing engagement surface comprising a metal, the metal comprising at least <NUM> wt. % of a diamond catalyst or diamond solvent based on a total weight of the metal, wherein the opposing engagement surface is movably engaged with each of the engagement surfaces; wherein the plurality of polycrystalline diamond elements are coupled with the drive shaft and the opposing engagement surface is a surface on the bearing housing, or wherein the plurality of polycrystalline diamond elements are coupled with the bearing housing and the opposing engagement surface is a surface on the drive; coupling a rotor with the second end of the drive shaft; coupling a stator with the rotor; and bearing radial and thrust loads on the drive shaft with the bearing assembly.

So that the manner in which the features and advantages of the systems, apparatus, and/or methods of the present disclosure may be understood in more detail, a more particular description briefly summarized above may be had by reference to the embodiments thereof which are illustrated in the appended drawings that form a part of this specification. It is to be noted, however, that the drawings illustrate only various exemplary embodiments and are therefore not to be considered limiting of the disclosed concepts as it may include other effective embodiments as well.

Systems, apparatus, and methods according to present disclosure will now be described more fully with reference to the accompanying drawings, which illustrate various exemplary embodiments. Concepts according to the present disclosure may, however, be embodied in many different forms and should not be construed as being limited by the illustrated embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough as well as complete and will fully convey the scope of the various concepts to those skilled in the art and the best and preferred modes of practice.

Embodiments of the present disclosure include tools (e.g., motors) and components thereof having polycrystalline radial bearings, systems including the same, and methods of making and using the same. The motors disclosed herein may be drilling motors for downhole drilling, including directional drilling, such as mud motors. The present invention includes drives shafts having polycrystalline diamond radial bearings thereon. The technology disclosed herein is applied to a drive shaft movably coupled within a housing. Definitions, Examples,.

Diamond Reactive Materials - As used herein, a "diamond reactive material" is a material that contains more than trace amounts of diamond catalyst or diamond solvent. As used herein, a diamond reactive material that contains more than "trace amounts" of diamond catalyst or diamond solvent, contains at least <NUM> percent by weight (wt. %) diamond catalyst or diamond solvent. In some aspects, the diamond reactive materials disclosed herein contain from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. % of diamond catalyst or diamond solvent. As used herein, a "diamond catalyst" is a chemical element, compound, or material capable of catalyzing graphitization of polycrystalline diamond, such as under load and at a temperature at or exceeding the graphitization temperature of diamond (i.e., about <NUM>). As used herein, a "diamond solvent" is a chemical element, compound, or material capable of solubilizing polycrystalline diamond, such as under load and at a temperature at or exceeding the graphitization temperature of diamond. Thus, diamond reactive materials include materials that, under load and at a temperature at or exceeding the graphitization temperature of diamond, can lead to wear, sometimes rapid wear, and failure of components formed of or including polycrystalline diamond, such as diamond tipped tools. Diamond reactive materials include, but are not limited to, metals, metal alloys, and composite materials that contain more than trace amounts of diamond catalyst or solvent elements. In some aspects, the diamond reactive materials are in the form of hardfacings, coatings, or platings. For example, and without limitation, the diamond reactive material may be ferrous, cobalt, nickel, ruthenium, rhodium, palladium, chromium, manganese, copper, titanium, tantalum, or alloys thereof. In some aspects, the diamond reactive material is a superalloy including, but not limited to, iron-based, cobalt-based and nickel-based superalloys. In certain aspects, the diamond reactive material is not and/or does not include (i.e., specifically excludes) so called "superhard materials. " As would be understood by one skilled in the art, "superhard materials" are a category of materials defined by the hardness of the material, which may be determined in accordance with the Brinell, Rockwell, Knoop and/or Vickers scales. For example, superhard materials include materials with a hardness value exceeding <NUM> gigapascals (GPa) when measured by the Vickers hardness test. As used herein, superhard materials include materials that are at least as hard as tungsten carbide tiles and/or cemented tungsten carbide, such as is determined in accordance with one of these hardness scales, such as the Brinell scale. One skilled in the art would understand that a Brinell scale test may be performed, for example, in accordance with ASTM E10-<NUM>; the Vickers hardness test may be performed, for example, in accordance with ASTM E92-<NUM>; the Rockwell hardness test may be performed, for example, in accordance with ASTM E18; and the Knoop hardness test may be performed, for example, in accordance with ASTM E384-<NUM>. The "superhard materials" disclosed herein include, but are not limited to, tungsten carbide (e.g., tile or cemented), infiltrated tungsten carbide matrix, silicon carbide, silicon nitride, cubic boron nitride, and polycrystalline diamond. Thus, in some aspects, the "diamond reactive material" is partially or entirely composed of material(s) (e.g., metal, metal alloy, composite) that is softer (less hard) than superhard materials, such as less hard than tungsten carbide (e.g., tile or cemented), as determined in accordance with one of these hardness tests, such as the Brinell scale.

Interfacing Polycrystalline Diamond with Diamond Reactive Materials - In some aspects, the present disclosure provides for interfacing the engagement between a rotor and stator with a polycrystalline diamond element in contact with a diamond reactive material. For example, the polycrystalline diamond element may be positioned and arranged on the stator for sliding contact with the rotor, where the rotor is formed of or includes at least some diamond reactive material. Alternatively, the polycrystalline diamond element may be positioned and arranged on the rotor for sliding contact with the stator, where the stator is formed of or includes at least some diamond reactive material. The polycrystalline diamond element may have an engagement surface for engagement with an opposing engagement surface of the diamond reactive material. As used herein, "engagement surface" refers to the surface of a material (e.g., polycrystalline diamond or diamond reactive materials) that is positioned and arranged within a bearing assembly such that, in operation of the bearing assembly, the engagement surface interfaces the contact between the two components (e.g., between the stator and the rotor). The "engagement surface" may also be referred to herein as the "bearing surface". In some aspects the opposing engagement surface includes or is composed of at least <NUM> wt. % of diamond reactive material, or from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. %, or from <NUM> to <NUM> wt. % of diamond reactive material.

Lapped or Polished - In certain applications, the polycrystalline diamond element, or at least the engagement surface thereof, is lapped or polished, optionally highly lapped or highly polished. Although highly polished polycrystalline diamond elements are preferred in at least some applications, the scope of this disclosure is not limited to highly polished polycrystalline diamond elements and includes polycrystalline diamond elements that are highly lapped or polished. As used herein, a surface is defined as "highly lapped" if the surface has a surface finish of 20µin (<NUM>) or about 20µin (<NUM>), such as a surface finish ranging from about <NUM> to about 22µin (<NUM> to about <NUM>. As used herein, a surface is defined as "polished" if the surface has a surface finish of less than about 10µin (<NUM>), or of from about <NUM> to about <NUM>µin (<NUM> to about <NUM>). As used herein, a surface is defined as "highly polished" if the surface has a surface finish of less than about 2µin (<NUM>), or from about <NUM>. 5µin (<NUM>) to less than about 2µin (<NUM>). In some aspects, engagement surface <NUM> has a surface finish ranging from <NUM>µin (<NUM>) to <NUM>µin (<NUM>), or from <NUM>µin (<NUM>) to <NUM>µin (<NUM>), or from <NUM>µin (<NUM>) to <NUM>µin (<NUM>), or from <NUM>µin (<NUM>) to <NUM>µin (<NUM>), or less than <NUM>µin (<NUM>), or less than <NUM>µin (<NUM>), or less than <NUM>µin (<NUM>), or any range therebetween. Polycrystalline diamond that has been polished to a surface finish of <NUM>. 5µin (<NUM>) has a coefficient of friction that is about half of standard lapped polycrystalline diamond with a surface finish of <NUM>-40µin (<NUM>-<NUM>). <CIT> and <CIT>. provide disclosure relevant to polishing of polycrystalline diamond. As would be understood by one skilled in the art, surface finish may be measured with a profilometer or with Atomic Force Microscopy. Table <NUM>, below, sets for a summary of coefficients of friction for various materials, including polished polycrystalline diamond, in both a dry, static state and a lubricated, static state, where the "first material" is the material that is moved relative to the "second material" to determine the CoF of the first material.

<FIG> depicts flow chart <NUM> of an emblematic generalized set of evaluation criteria for the use of the technology of this application in a dry, non-lubricated environment. As indicated by box <NUM>, first it is evaluated if the maximum sliding speed in an application is less than <NUM>/s. As used herein the "sliding speed", also referred to as the "sliding interface speed", is the speed with which two components in contact move relative to one another (e.g., the speed at which a rotor, in contact with a stator, moves relative to the stator). While <FIG> is described with respect to a rotor and stator, the same method may be applied a drive shaft and a bearing housing, or other components that are movably engaged.

If it is determined that the maximum sliding speed is not be less than <NUM>/s, then, as indicated by box <NUM>, it is determined that the evaluated application is not a candidate for use of a polycrystalline diamond element is sliding engagement with a diamond reactive material because the sliding speed is too high. One skilled in the art would understand that, in a lubricated or wet environment, the sliding interface speed can be significantly higher than in a dry, non-lubricated environment (as is herein evaluated).

If it is determined that the maximum sliding speed is less than <NUM>/s, then, as indicated by box <NUM>, the configuration (e.g., shape, size, and arrangement) of the polycrystalline diamond element is selected depending on the particular application at hand. Box <NUM> sets forth various non-limiting polycrystalline diamond element configurations for sliding engagement with diamond reactive materials in various bearing configurations. For example, a planar polycrystalline diamond element may be selected for use on a stator that is engaged with a cylindrical rotor formed of or including at least some diamond reactive material; a convex polycrystalline diamond element may be selected for use on a stator that is engaged with a cylindrical rotor formed of or including at least some diamond reactive material; a polycrystalline diamond element having a concave, or at least slightly concave, surface may be selected for use on a stator that is engaged with a cylindrical rotor formed of or including at least some diamond reactive material; a polycrystalline diamond element having a convex, or at least slightly convex, surface may be selected for use on a rotor that is engaged with a cylindrical stator formed of or including at least some diamond reactive material; a chisel shaped polycrystalline diamond element may be selected for use on a stator that is engaged with a grooved rotor formed of or including at least some diamond reactive material; a dome or hemisphere shaped polycrystalline diamond element may be selected for use on a stator that is engaged with a grooved rotor formed of or including at least some diamond reactive material; a planar polycrystalline diamond element may be selected for use on a conic shaped stator that is engaged with a conic shaped rotor formed of or including at least some diamond reactive material; a polycrystalline diamond element having a convex, or at least slightly convex, surface may be selected for use on a conic shaped stator that is engaged with a conic shaped rotor formed of or including at least some diamond reactive material; a polycrystalline diamond element having a convex, or at least slightly convex, surface may be selected for use on a conic shaped rotor that is engaged with a conic shaped stator formed of or including at least some diamond reactive material; a polycrystalline diamond element having a concave, or at least slightly concave, surface may be selected for use on a conic shaped stator that is engaged with a conic shaped rotor formed of or including at least some a diamond reactive material; a polycrystalline diamond element having a convex, or at least slightly convex, surface may be selected for use on a spherical shaped rotor that is engaged with a spherical shaped stator formed of or including at least some diamond reactive material; or a polycrystalline diamond element having a planar, convex, or at least slightly convex surface may be selected for use on a spherical shaped stator that is engaged with a spherical shaped rotor formed of or including at least some diamond reactive material. One skilled in the art would understand that the present disclosure is not limited to these particular selected shapes and contours, and that the shapes, including surface contouring, of the rotors, stators, polycrystalline diamond elements, and other application specific components may vary depending on the particular application.

After selecting the configuration, as set forth in box <NUM>, the maximum contact pressure per polycrystalline diamond element is calculated. As set forth in box <NUM>, the maximum contact pressure per polycrystalline diamond element is calculated based on the number of polycrystalline diamond elements and the anticipated load, including radial, axial, bending, or other loads. The maximum contact pressure may be determined by methods known to those skilled in the art.

After calculation of the maximum contact pressure per polycrystalline diamond element, the calculated maximum pressure per polycrystalline diamond element is multiplied by a safety factor, as set forth in box <NUM>. The application of the safety factor, over and above the maximum pressure determined in box <NUM>, may be set and applied at the discretion of a designer, for example. Thus, the safety factor, if applied, provides for a reduced pressure per polycrystalline diamond element relative to the maximum contact pressure per polycrystalline diamond element.

In box <NUM>, it is determined whether the calculated maximum pressure is below maximum allowable pressure for anticipated cycles of the apparatus. As would be understood by those skilled in the art, the fatigue on the diamond reactive material is the limiting factor. The load is at the diamond/diamond reactive material (e.g., metal) interface. The more the PDC elements in an assembly, the lower the instant load on the metal. S-N curves (contact stress to cycles) can be used to facilitate making the determination in box <NUM>.

If, per box <NUM>, it is determined that the calculated pressure is not below the maximum allowable pressure, then, as indicated in box <NUM>, additional polycrystalline diamond elements are deployed to the design configuration that was selected in box <NUM>. After these additional polycrystalline diamond elements are deployed, the thus modified design configuration is evaluated per boxes <NUM> and <NUM> before being, once again, assessed per the criteria of box <NUM>.

If, per box <NUM>, it is determined that the calculated pressure is below the maximum allowable pressure, then, as indicated in box <NUM>, the proposed design configuration is then created by deploying at least the minimum number of polycrystalline diamond elements indicated as required by the prior boxes <NUM>-<NUM> onto the components of the chosen design configuration of box <NUM> (e.g., attaching the minimum number of polycrystalline diamond elements onto the stator or rotor).

At box <NUM>, it is determined whether the minimum number of polycrystalline diamond elements, per box <NUM>, will fit on the chosen configuration of box <NUM>. If it is determined that, the minimum number of polycrystalline diamond elements will fit on the chosen configuration of box <NUM>, then the bearing assembly in the rotor and stator is produced, as shown in box <NUM>. If it determined that the minimum number of polycrystalline diamond elements will not fit on the chosen configuration of box <NUM>, then the chosen configuration of box <NUM> is determined to not be a candidate for use of a polycrystalline diamond element in sliding engagement with a diamond reactive material, per box <NUM>.

The designer of the bearing configuration would also have the option (not shown) of choosing an alternative bearing configuration from box <NUM> if the required minimum number of polycrystalline diamond elements will not fit on the originally chosen design configuration. Alternatively, the safety factor can be lowered to reduce the minimum number of polycrystalline diamond elements required. One skilled in the art would understand that the criteria set forth in <FIG> is exemplary only, that other criteria may be evaluated depending on the particular application, and that, for at least some applications, some of the criteria set forth in <FIG> may be left out without departing from the scope of this disclosure.

Various exemplary rotor and stator radial bearing assemblies will now be described with reference to <FIG>. In <FIG>, like reference numerals refer to like elements. For example, an exemplary assembly is identified with reference numeral "<NUM>" in <FIG> and is identified with reference numeral "<NUM>" in <FIG>.

<FIG> is a partial side view of a rotor and stator radial bearing assembly, and <FIG> is a cross-sectional view of the rotor and stator radial bearing assembly of <FIG> taken along line A-A. With reference to both <FIG>, rotor and stator radial bearing assembly <NUM> will be described.

Rotor and stator radial bearing assembly <NUM> includes stator <NUM> engaged with rotor <NUM>. Four planar polycrystalline diamond elements <NUM> are fitted into stator <NUM> to provide for sliding engagement between stator <NUM> and rotor <NUM>, where rotor <NUM> is formed of or includes at least some diamond reactive material. Polycrystalline diamond elements <NUM> are deployed (e.g., mechanically fitted) in stator <NUM> within loading ports <NUM>, which are ports formed in and/or positioned within stator body <NUM>. For example, and without limitation, each polycrystalline diamond element <NUM> may be press fit, glued, brazed, threaded, or otherwise mounted on stator <NUM> (or rotor in other applications) via methods known to those skilled in the art. One skilled in the art would understand that the present disclosure is not limited to these particular attachment methods or to the use of ports within the stator body, and that the polycrystalline diamond elements may be attached to the stator or rotor by any of a variety of methods. Further, while shown as including equally spaced, planar polycrystalline diamond elements, one skilled in the art would understand that the number, spacing, armament, shape, and size of the polycrystalline diamond elements may vary depending upon any number of various design criteria including, but not limited to, the criteria set forth in <FIG>. In some aspects, polycrystalline diamond elements are composed of thermally stable polycrystalline diamond, either supported or unsupported by tungsten carbide, or polycrystalline diamond compact.

Each polycrystalline diamond element <NUM> includes an engagement surface <NUM> (here shown as planar surfaces), and rotor <NUM> includes opposing engagement surface <NUM>. Polycrystalline diamond elements <NUM> are positioned on stator <NUM> in secure contact with rotor <NUM>, to limit lateral movement of rotor <NUM> while allowing for free sliding rotation of rotor <NUM> during operation. Polycrystalline diamond elements <NUM> are positioned and arranged such that engagement surfaces <NUM> are in contact (e.g., sliding contact) with opposing engagement surface <NUM>. Thus, engagement surfaces <NUM> and opposing engagement surface <NUM> interface the sliding contact between rotor <NUM> and stator <NUM>. In some embodiments, rotor <NUM> has a rotational velocity, engagement between engagement surface <NUM> and opposing engagement surface <NUM> defines a contact area that is independent of the rotational velocity of rotor <NUM>. In some embodiments, rotor <NUM> has a variable rotational velocity, and engagement surface <NUM> follows an engagement path on opposing engagement surface <NUM> that is constant through the variable rotational velocities.

<FIG> depict a rotor and stator such as would be used in a downhole pump or motor. However, one skilled in the art would understand that radial bearings for other applications, as well as discrete radial bearings, may be designed and manufactured in the same or similar manner in accordance with this disclosure. Non-limiting proximal and distal dimensions for such a discrete bearing are indicated by dashed lines <NUM> shown in <FIG>. As shown in <FIG>, optionally, a through bore <NUM> is provided in rotor <NUM>, which could be used in a discrete bearing, for example. As is evident in <FIG>, polycrystalline diamond elements <NUM> are deployed in stator <NUM> to radially support and provide sliding engagement with rotor <NUM>.

Although <FIG> depict an assembly that includes four polycrystalline diamond elements <NUM>, one skilled in the art would understand that less than four polycrystalline diamond elements, such as three polycrystalline diamond elements, or more than four polycrystalline diamond elements may be used depending on the particular application and configuration, such as the space available such polycrystalline diamond elements on the stator or rotor. Further, although <FIG> show a single circumferential set of polycrystalline diamond elements <NUM>, it would be understood by those skilled in the art that one or more additional circumferential sets of polycrystalline diamond elements may be deployed in the stator (or rotor) to increase lateral support and lateral load taking capability of the bearing assembly.

<FIG> depict rotor and stator radial bearing assembly <NUM>, which is substantially similar to that of <FIG>, with the exception that polycrystalline diamond elements <NUM> have convex engagement surfaces <NUM> rather than the flat, planar engagement surfaces of <FIG>.

With reference to <FIG>, rotor and stator radial bearing <NUM> includes convex polycrystalline diamond elements <NUM> fitted into stator body <NUM> of stator <NUM> to provide for sliding engagement with rotor <NUM>, formed of or including at least some diamond reactive material. Polycrystalline diamond elements <NUM> are deployed in stator <NUM> through loading ports <NUM>, and may be press fit, glued, brazed, threaded, or otherwise mounted using methods known to those skilled in the art. Polycrystalline diamond elements <NUM> are placed into a secure contacting position with rotor <NUM> to limit lateral movement of rotor <NUM> while allowing for free sliding rotation of rotor <NUM> during operation. As is evident from <FIG>, polycrystalline diamond elements <NUM> are deployed in stator <NUM> to radially support and provide sliding engagement with rotor <NUM>. <FIG> also shows optional through bore <NUM> such as could be used in a discrete bearing.

Although <FIG> depict a rotor and stator such as would be used in a downhole pump or motor, other assemblies, including discrete radial bearing assemblies, may be designed and manufactured in the same or substantially the same way. Non-limiting proximal and distal dimensions for such a discrete bearing are indicated by dashed lines <NUM>. Further, although <FIG> show four polycrystalline diamond elements <NUM>, it would be understood by those skilled in the art that fewer (e.g., three) or more polycrystalline diamond elements may be deployed in stator <NUM>. Additionally, although <FIG> show a single circumferential set of polycrystalline diamond elements <NUM>, it would be understood by those skilled in the art that one or more additional circumferential sets of polycrystalline diamond elements may be deployed in the stator to increase lateral support and lateral load taking capability of the bearing assembly.

As with assembly <NUM>, in operation engagement surface <NUM> interfaces with opposing engagement surface <NUM> to bear load between rotor <NUM> and stator <NUM>.

<FIG> depict rotor and stator radial bearing assembly <NUM>, which is substantially similar to that of <FIG>, with the exception that polycrystalline diamond elements <NUM> has concave, or at least slightly concave, engagement surfaces <NUM> rather than the flat, planar engagement surfaces of <FIG> or the convex engagement surfaces of <FIG>.

Slightly concave polycrystalline diamond elements <NUM> are fitted into stator body <NUM> of stator <NUM> to provide for sliding engagement with rotor <NUM>. Polycrystalline diamond elements <NUM> are deployed in stator <NUM> through loading ports <NUM>. Polycrystalline diamond elements <NUM> may be press fit, glued, brazed, threaded, or otherwise mounted using methods known to those skilled in the art. Polycrystalline diamond elements <NUM> are placed into secure contacting position with rotor <NUM> to limit lateral movement of rotor <NUM> while allowing for free sliding rotation of rotor <NUM> during operation.

As with assembly <NUM>, in operation engagement surface <NUM> interfaces with opposing engagement surface <NUM> to bear load between rotor <NUM> and stator <NUM>. The at least slight concavity of each polycrystalline diamond element <NUM> is oriented with the axis of the concavity, in line with the circumferential rotation of rotor <NUM>; thereby ensuring no edge contact between polycrystalline diamond elements <NUM> and rotor <NUM> and providing for linear area contact between polycrystalline diamond elements <NUM> and rotor <NUM>, generally with the deepest portion of the concavity. That is, engagement between polycrystalline diamond elements <NUM> and rotor <NUM> is exclusively interfaced by engagement surface <NUM> and opposing engagement surface <NUM>, such that edge or point <NUM> of polycrystalline diamond elements <NUM> do not make contact with rotor <NUM>. As such, only linear area contact, and no edge or point contact, occurs between polycrystalline diamond elements <NUM> and rotor <NUM>. As is evident from <FIG>, polycrystalline diamond elements <NUM> are deployed in stator <NUM> to radially support and provide sliding engagement with rotor <NUM>. <FIG> also shows optional through bore <NUM> such as could be used in a discrete bearing.

Although <FIG> depict a rotor and stator such as would be used in a downhole pump or motor, assemblies, including a discrete radial bearing assembly, may be designed and manufactured in the same or substantially the same way. Non-limiting proximal and distal dimensions for such a discrete bearing are indicated by dashed lines <NUM>. Further, although <FIG> show four polycrystalline diamond elements <NUM>, it would be understood by those skilled in the art that fewer (e.g., three) or more polycrystalline diamond elements may be deployed in stator <NUM>. Additionally, although <FIG> show a single circumferential set of polycrystalline diamond elements <NUM>, it would be understood by those skilled in the art that one or more additional circumferential sets of polycrystalline diamond elements may be deployed in the stator to increase lateral support and lateral load taking capability of the bearing assembly.

<FIG> depict rotor and stator radial bearing assembly <NUM>, which is substantially similar to that of <FIG>, with the exception that polycrystalline diamond elements <NUM>, having the convex, dome shaped engagement surfaces <NUM>, are installed on rotor <NUM> rather than on the stator.

Convex polycrystalline diamond elements <NUM> are fitted into rotor body <NUM> of rotor <NUM> to provide for sliding engagement with stator <NUM>, which is formed of or includes at least some diamond reactive material. Polycrystalline diamond elements <NUM> are deployed in rotor <NUM> in sockets <NUM> formed into and/or positioned in rotor body <NUM>. Polycrystalline diamond elements <NUM> may be press fit, glued, brazed, threaded, or otherwise mounted using methods known to those skilled in the art. Polycrystalline diamond elements <NUM> are placed into a secure contacting position relative to stator <NUM> to limit lateral movement of rotor <NUM> while allowing for free sliding rotation of rotor <NUM> during operation. As is evident from <FIG>, polycrystalline diamond elements <NUM> are deployed in rotor <NUM> to radially support and provide sliding engagement with stator <NUM>. <FIG> also shows optional through bore <NUM> such as could be used in a discrete bearing.

Although <FIG> depict a rotor and stator such as would be used in a downhole pump or motor, other assemblies, including a discrete radial bearing assembly, may be designed and manufactured in the same or similar way. Non-limiting proximal and distal dimensions for such a discrete bearing are indicated by dashed lines <NUM>. Further, although <FIG> show four polycrystalline diamond elements <NUM>, one skilled in the art would understand that fewer (e.g., three) or more polycrystalline diamond elements may be deployed in rotor <NUM>. Additionally, although <FIG> show a single circumferential set of polycrystalline diamond elements <NUM>, it would be understood by one skilled in the art that one or more additional circumferential sets of polycrystalline diamond elements may be deployed in the rotor to increase lateral support and lateral load taking capability of the bearing assembly.

Thus, contrary to the embodiments shown in <FIG>, in the embodiment shown in <FIG>, the engagement surfaces <NUM> are on the rotor <NUM>, and the opposing engagement surface <NUM> is on the stator <NUM>.

<FIG> depict rotor and stator radial bearing assembly <NUM> with chisel shaped polycrystalline diamond elements <NUM> fitted into stator body <NUM> of stator <NUM> to provide for sliding engagement with rotor <NUM>, which is formed of or includes at least some diamond reactive material. Polycrystalline diamond elements <NUM> are deployed in stator <NUM> through loading ports <NUM>, which are formed in and/or positioned in stator body <NUM>. Polycrystalline diamond elements <NUM> may be press fit, glued, brazed, threaded, or otherwise mounted using methods known to those skilled in the art.

Polycrystalline diamond elements <NUM> are placed into a secure contacting position within radial/thrust surface groove <NUM> of rotor <NUM> to limit lateral and axial movement of rotor <NUM> while allowing for free sliding rotation of rotor <NUM> during operation. Chisel shaped polycrystalline diamond elements <NUM> are positioned, arranged, shaped, sized, and oriented to slidingly engage into the mating radial/thrust surface groove <NUM> of rotor <NUM>. Chisel shaped polycrystalline diamond elements <NUM> include engagement surface (defined by the chisel shaped polycrystalline diamond elements <NUM>), which interfaces in contact with opposing engagement surface, here the surface of radial/thrust surface groove <NUM>. It is evident from <FIG> that chisel shape polycrystalline diamond elements <NUM> are deployed in stator <NUM> to radially and axially support and provide sliding engagement with rotor <NUM>. <FIG> also depicts optional through bore <NUM> such as could be used in a discrete bearing. The embodiment shown in <FIG> may further act as a rotor catch.

Although <FIG> depict a rotor and stator such as would be used in a downhole pump or motor, other assemblies, including a discrete radial bearing assembly, may be designed and manufactured in the same or similar way. Non-limiting proximal and distal dimensions for such a discrete bearing are indicated by dashed lines <NUM>. Further, although <FIG> depict four polycrystalline diamond elements <NUM>, it would be understood by one skilled in the art that fewer (e.g., three) or more polycrystalline diamond elements <NUM> may be deployed in stator <NUM>. Additionally, although <FIG> depict a single circumferential set of polycrystalline diamond elements <NUM>, it would be understood by one skilled in the art that one or more additional circumferential sets of polycrystalline diamond elements may be deployed in the stator to increase lateral and axial support and lateral and axial load taking capability of the bearing assembly.

<FIG> depict rotor and stator radial bearing assembly <NUM>, which is substantially similar to that of <FIG>, with the exception that polycrystalline diamond elements <NUM> have dome or hemisphere shaped engagement surfaces <NUM> rather chisel shaped polycrystalline diamond elements.

Dome or hemisphere shaped polycrystalline diamond elements <NUM> are fitted into stator housing <NUM> of stator <NUM> to provide for sliding engagement with rotor <NUM>. Polycrystalline diamond elements <NUM> are deployed in stator <NUM> through loading ports <NUM> formed in and/or positioned in stator body <NUM>. Polycrystalline diamond elements <NUM> may be press fit, glued, brazed, threaded, or otherwise mounted using methods known to those skilled in the art. Polycrystalline diamond elements <NUM> are placed into a secure contacting position relative to radial/thrust surface groove <NUM> of rotor <NUM> to limit lateral and axial movement of rotor <NUM> while allowing for free sliding rotation of rotor <NUM> during operation. Dome or hemisphere polycrystalline diamond elements <NUM> slidingly engage the mating radial/thrust surface groove <NUM> of rotor <NUM>. Dome or hemisphere polycrystalline diamond elements <NUM> define engagement surface, which interfaces in contact with opposing engagement surface, here the surface of radial/thrust surface groove <NUM>. As is evident from <FIG>, dome or hemisphere polycrystalline diamond elements <NUM> are deployed in stator <NUM> to radially and axially support and provide sliding engagement with rotor <NUM>. <FIG> also shows optional through bore <NUM> such as could be used in a discrete bearing. The embodiment shown in <FIG> may further act as a rotor catch.

Although <FIG> depict a rotor and stator such as would be used in a downhole pump or motor, other assemblies, including a discrete radial bearing assembly, may be designed and manufactured in the same or similar way. Non-limiting proximal and distal dimensions for such a discrete bearing are indicated by dashed lines <NUM>. Further, although <FIG> depict four polycrystalline diamond elements <NUM>, it would be understood by those skilled in the art that fewer (e.g., three) or more polycrystalline diamond elements may be deployed in stator <NUM>. Additionally, although <FIG> depict a single circumferential set of polycrystalline diamond elements, it would be understood by those skilled in the art that one or more additional circumferential sets of polycrystalline diamond elements may be deployed in the stator to increase lateral and axial support and lateral and axial load taking capability of the bearing assembly.

<FIG> depict rotor and stator radial bearing assembly <NUM> including planar polycrystalline diamond elements <NUM> fitted into stator body <NUM> of stator <NUM> to provide for sliding engagement with rotor <NUM>, which is formed of or includes at least some diamond reactive material. Polycrystalline diamond elements <NUM> are deployed in stator <NUM> through loading ports <NUM> formed in and/or positioned in stator body <NUM>. Polycrystalline diamond elements <NUM> may be press fit, glued, brazed, threaded, or otherwise mounted using methods known to those skilled in the art.

Polycrystalline diamond elements <NUM> are placed into a secure contacting position relative to radial/thrust conical surface <NUM> of rotor <NUM> to limit lateral and upward axial movement of rotor <NUM> while allowing for free sliding rotation of rotor <NUM> during operation.

The planar polycrystalline diamond elements <NUM> slidingly engage the mating radial/thrust conical surface of rotor <NUM>, such that engagement surfaces <NUM> contact and interface with opposing engagement surface <NUM>. As is evident from <FIG>, polycrystalline diamond elements <NUM> are deployed in stator <NUM> to radially and axially support and provide sliding engagement with rotor <NUM>.

Although <FIG> depict four polycrystalline diamond elements <NUM>, it would be understood by those skilled in the art that fewer (e.g., three) or more polycrystalline diamond elements may be deployed in stator <NUM>. Further, although <FIG> depict a single circumferential set of polycrystalline diamond elements <NUM>, it would be understood that one or more additional circumferential sets of polycrystalline diamond elements may be deployed in the stator to increase lateral and axial support and lateral and axial load taking capability of the bearing assembly.

While <FIG> are described as a bearing arrangement between a rotor <NUM> and stator <NUM>, one skilled in the art would understand that the rotor may, instead, be a drive shaft, and the stator may, instead, be a bearing housing.

<FIG> depict rotor and stator radial bearing assembly <NUM>, which is substantially similar to that of <FIG>, with the exception that polycrystalline diamond elements <NUM> have convex engagement surfaces <NUM> rather than planar engagement surfaces.

Convex polycrystalline diamond elements <NUM> are fitted into stator body <NUM> of stator <NUM> to provide for sliding engagement with rotor <NUM>. Polycrystalline diamond elements <NUM> are deployed in stator <NUM> through loading ports <NUM> formed in and/or positioned in stator body <NUM>. Polycrystalline diamond elements <NUM> may be press fit, glued, brazed, threaded, or otherwise mounted using methods known to those skilled in the art.

Convex polycrystalline diamond elements <NUM> are placed into secure contacting position with radial/thrust conical surface <NUM> of rotor <NUM> to limit lateral and upward axial movement of rotor <NUM> while allowing for free sliding rotation of rotor <NUM> during operation. Polycrystalline diamond elements <NUM> slidingly engage the mating radial/thrust conical surface of rotor <NUM>, such that engagement surfaces <NUM> contact and interface with opposing engagement surface <NUM>.

As is evident from <FIG>, convex polycrystalline diamond elements <NUM> are deployed in stator <NUM> to radially and axially support and provide sliding engagement with rotor <NUM>.

Although <FIG> depict four polycrystalline diamond elements <NUM>, it would be understood by those skilled in the art that fewer (e.g., three) or more polycrystalline diamond elements may be deployed in stator <NUM>. Further, although <FIG> depict a single circumferential set of polycrystalline diamond elements <NUM>, it would be understood by those skilled in the art that one or more additional circumferential sets of polycrystalline diamond elements may be deployed in the stator to increase lateral and axial support and lateral and axial load taking capability of the bearing assembly.

<FIG> depict a rotor and stator radial and thrust bearing assembly <NUM> including convex polycrystalline diamond elements <NUM> fitted into rotor body <NUM> of rotor <NUM> to provide for sliding engagement with stator <NUM>, which is formed of or includes at least some diamond reactive material. Polycrystalline diamond elements <NUM> are deployed in rotor <NUM> in sockets <NUM> formed in and/or positioned in rotor body <NUM>. Polycrystalline diamond elements <NUM> may be press fit, glued, brazed, threaded, or otherwise mounted using methods known to those skilled in the art.

Convex polycrystalline diamond elements <NUM> are placed into a secure contacting position within radial/thrust conical surface <NUM> of stator <NUM> to limit lateral and upward axial movement of rotor <NUM> while allowing for free sliding rotation of rotor <NUM> during operation. The convex polycrystalline diamond elements <NUM> slidingly engage the mating radial/thrust conical surface of stator <NUM>, such that engagement surfaces <NUM> contact and interface with opposing engagement surface <NUM>. As is evident from <FIG>, convex polycrystalline diamond elements <NUM> are deployed in rotor <NUM> to radially and axially support and provide sliding engagement with subject material stator <NUM>.

Although <FIG> depict four polycrystalline diamond elements <NUM>, it would be understood by those skilled in the art that fewer (e.g., three) or more polycrystalline diamond elements may be deployed in rotor <NUM>. Further, although <FIG> depict a single circumferential set of polycrystalline diamond elements <NUM>, it would be understood by those skilled in the art that one or more additional circumferential sets of polycrystalline diamond elements may be deployed in the rotor to increase lateral and axial support and lateral and axial load taking capability of the bearing assembly.

<FIG> depict rotor and stator radial and thrust bearing assembly <NUM> including concave, or at least slightly concave, polycrystalline diamond elements <NUM> fitted into stator body <NUM> of stator <NUM> to provide for sliding engagement with rotor <NUM>, which is formed of or includes at least some diamond reactive material. Polycrystalline diamond elements <NUM> are deployed in stator <NUM> through loading ports <NUM> formed and/or positioned therethrough. Polycrystalline diamond elements <NUM> may be press fit, glued, brazed, threaded, or otherwise mounted using methods known to those skilled in the art.

Polycrystalline diamond elements <NUM> are placed into a secure contacting position within radial/thrust conical surface <NUM> of rotor <NUM> to limit lateral and upward axial movement of rotor <NUM> while allowing for free sliding rotation of rotor <NUM> during operation. Polycrystalline diamond elements <NUM> are oriented with the axis of the concavity in line with the circumferential rotation of the rotor <NUM> to ensure no edge or point contact, and thus ensure only linear area contact generally with the deepest portion of the concavity. The slightly concave polycrystalline diamond elements <NUM> slidingly engage the radial/thrust conical surface of rotor <NUM>, such that engagement surfaces <NUM> contact and interface with opposing engagement surface <NUM>.

As is evident from <FIG>, slightly concave polycrystalline diamond elements <NUM> are deployed in stator <NUM> to radially and axially support and provide sliding engagement with rotor <NUM>.

Although <FIG> depict four polycrystalline diamond elements <NUM>, it would be understood by those skilled in the art that fewer (e.g., three) or more polycrystalline diamond elements may be deployed in stator <NUM>. Further, although <FIG> show a single circumferential set of polycrystalline diamond elements <NUM>, it would be understood by those skilled in the art that one or more additional circumferential sets of polycrystalline diamond elements may be deployed in the stator to increase lateral and axial support and lateral and axial load taking capability of the bearing assembly.

<FIG> depict rotor and stator radial and thrust bearing assembly <NUM>, including convex polycrystalline diamond elements <NUM> are fitted into rotor body <NUM> of rotor <NUM> to provide for sliding engagement with stator <NUM>. Polycrystalline diamond elements <NUM> are deployed in rotor <NUM> in sockets <NUM> formed in and/or positioned in rotor body <NUM>. Polycrystalline diamond elements <NUM> may be press fit, glued, brazed, threaded, or otherwise mounted using methods known to those skilled in the art.

Convex polycrystalline diamond elements <NUM> are placed into a secure contacting position within radial/thrust concave curved surface <NUM> of stator <NUM> to limit lateral and upward axial movement of rotor <NUM> while allowing for free sliding rotation of rotor <NUM> during operation. Convex polycrystalline diamond elements <NUM> slidingly engage the mating radial/ thrust concave curved surface of stator <NUM>, such that engagement surfaces <NUM> engage with radial/thrust concave curved surface <NUM>. In the embodiment of <FIG> and 121B, the radial/thrust concave curved surface <NUM> is or forms the opposing engagement surface. In the assembly <NUM>, the contact areas on the convex polycrystalline diamond elements <NUM> are generally circular. However, one skilled in the art would understand that the polycrystalline diamond elements are not limited to having such a contact area.

As is evident from <FIG>, convex polycrystalline diamond elements <NUM> are deployed in rotor <NUM> to radially and axially support and provide sliding engagement with stator <NUM>.

<FIG> depict a partial side view of a rotor and stator radial and thrust bearing assembly <NUM> including planar (or domed, not shown) polycrystalline diamond elements <NUM> fitted into stator body <NUM> of stator <NUM> to provide for sliding engagement with rotor <NUM>, which is formed of or includes at least some diamond reactive material. Polycrystalline diamond elements <NUM> are deployed in stator <NUM> through loading ports <NUM> formed in and/or positioned in stator body <NUM>. Polycrystalline diamond elements <NUM> may be press fit, glued, brazed, threaded, or otherwise mounted using methods known to those skilled in the art.

Polycrystalline diamond elements <NUM> are placed into a secure contacting position with radial/thrust convex curved surface <NUM> of rotor <NUM> to limit lateral and upward axial movement of rotor <NUM> while allowing for free sliding rotation of rotor <NUM> during operation. Radial/thrust convex curved surface <NUM> is or forms the opposing engagement surface. Polycrystalline diamond elements <NUM> slidingly engage the radial/thrust convex curved surface <NUM> of rotor <NUM>, such that engagement surface <NUM> is engaged with the opposing engagement surface (i.e., radial/thrust convex curved surface <NUM>). In the assembly <NUM>, the contact areas on the planar or domed polycrystalline diamond elements are typically circular. However, one skilled in the art would understand that the polycrystalline diamond elements may have different contact areas.

As is evident from <FIG>, planar polycrystalline diamond elements <NUM> are deployed in stator <NUM> to radially and axially support and provide sliding engagement with rotor <NUM>.

Although <FIG> show four polycrystalline diamond elements <NUM>, it would be understood by those skilled in the art that fewer (e.g., three) or more polycrystalline diamond elements may be deployed in stator <NUM>. Further, although <FIG> depict a single circumferential set of polycrystalline diamond elements <NUM>, it would be understood by those skilled in the art that one or more additional circumferential sets of polycrystalline diamond elements may be deployed in the stator to increase lateral and axial support and lateral and axial load taking capability of the bearing assembly.

As is evident in view of <FIG>, some aspects of the present disclosure include high-performance radial bearings incorporating polycrystalline diamond elements in sliding engagement with curved or cylindrical surfaces formed of or including at least some diamond reactive material. Some such aspects include high-performance radial bearings where a diamond reactive material containing rotor is put into sliding contact with preferably three or more polycrystalline diamond elements mounted on a stator. The polycrystalline diamond elements of the stator are preferably planar faced, but may also be slightly concave, convex, or any combination of the three. The facial contours of the polycrystalline diamond elements of the stator need not, and preferably do not, match the curve of the circumference of the stator. Although three or more polycrystalline diamond elements are preferred, the technology of the application may be practiced with as few as one or two polycrystalline diamond elements, such as where the polycrystalline diamond elements are used to reduce wear and friction on the gravitational low side of a stator in a horizontally oriented positive displacement pump or opposite the scribe side of a directional drilling assembly.

In certain applications, the bearing assemblies disclosed herein are configured to resist thrust load. At least some embodiments of the bearing assemblies disclosed herein are capable of simultaneously handling components of both radial and thrust loads.

At least some embodiments of the bearing assemblies disclosed are economically viable and of a relatively large diameter.

In some aspects, the polycrystalline diamond elements are subjected to edge radius treatment. Edge radius treatment of polycrystalline diamond elements are well known in the art. In some embodiments of the technology of this application that employ planar or concave polycrystalline diamond elements, it is preferred to employ edge radius treatment of such polycrystalline diamond elements. One purpose of employing an edge radius treatment is to reduce or avoid potential for outer edge cutting or scribing at the outer limits of the linear engagement area of a given polycrystalline diamond elements with the opposing engagement surface (e.g., a curved surface.

In certain applications, the polycrystalline diamond elements disclosed herein have increased cobalt content transitions layers between the outer polycrystalline diamond surface and a supporting tungsten carbide slug, as is known in the art.

The polycrystalline diamond elements may be supported by tungsten carbide, or may be unsupported, "standalone" polycrystalline diamond elements that are mounted directly to the bearing component.

The polycrystalline diamond elements may by non-leached, leached, leached and backfilled, thermally stable, coated via chemical vapor deposition (CVD), or processed in various ways as known in the art.

The polycrystalline diamond elements may have diameters as small as <NUM> (about <NUM>/<NUM>") or as large as <NUM> (about <NUM>"), depending on the application and the configuration and diameter of the bearing. Typically, the polycrystalline diamond elements have diameters between <NUM> (about <NUM>/<NUM>") and <NUM> (about <NUM>").

Although the polycrystalline diamond elements are most commonly available in cylindrical shapes, it is understood that the technology of the application may be practiced with polycrystalline diamond elements that are square, rectangular, oval, any of the shapes described herein with reference to the Figures, or any other appropriate shape known in the art. In some applications, the radial bearings have one or more convex, contoured polycrystalline diamond elements mounted on a rotor (or stator) in sliding contact with a stator (or rotor).

In some applications, the polycrystalline diamond elements are deployed in rings along the bearing component. A non-limiting example is a ring of five planar face polycrystalline diamond elements deployed on a distal portion of a stator and another ring of five planar face polycrystalline diamond elements deployed on a proximal portion of the stator. Thus, the high-performance polycrystalline diamond elements bearing assemblies can be deployed to ensure stable operation along the length of the stator/rotor interface, while requiring less total polycrystalline diamond elements than are used in prior, existing assemblies.

The polycrystalline diamond elements may be arranged in any pattern, layout, spacing or staggering within the bearing assembly to provide the desired support, without concern for the need for overlapping contact with polycrystalline diamond elements engagement surfaces on the opposing bearing component.

The polycrystalline diamond elements disclosed herein are, in some embodiments, not shaped to conform precisely to the opposing engagement surface. In certain embodiments, the sliding interface contact area of the engagement surface of the polycrystalline diamond element is less than <NUM>%, or less than <NUM>%, or less than <NUM>%, or less than <NUM>% of the total surface area of the polycrystalline diamond element. As used herein, the "contact area" of the engagement surface refers to the surface area of the engagement surface that is in contact with the opposing engagement surface. In some embodiments, the engagement surface is in sliding engagement with the opposing engagement surface along a contact area, the opposing engagement surface rotates about an axis of rotation, and any imaginary line extending from and normal to the contact area surface is at an angle relative to the axis of rotation. In some embodiments, the engagement surface is in sliding contact with the opposing engagement surface through a substantial portion of its use profile.

A key performance criterion is that the polycrystalline diamond element is configured and positioned in such a way as to preclude any edge or point contact with the opposing engagement surface or component. For a planar faced polycrystalline diamond element placed on the stator, such polycrystalline diamond elements typically experience less than full face contact with the rotor. That is, as the rotor rotates against the polycrystalline diamond elements, the engagement surface contact area is less than full face. For polycrystalline diamond elements, mounted on either the rotor or stator, that are at least slightly domed or convex, such polycrystalline diamond elements exhibit a small, generally circular engagement surface contact area. If the convex polycrystalline diamond elements, mounted on either the rotor or stator, are saddle shaped, then the polycrystalline diamond elements exhibit a small linear area engagement surface contact area. For slightly concave polycrystalline diamond elements that are deployed on the stator, a somewhat narrow linear engagement surface contact area is exhibited on each polycrystalline diamond element.

As previously described, the polycrystalline diamond elements may be mounted directly to the bearing element (e.g., stator or rotor) via methods known in the art including, but not limited to, brazing, gluing, press fitting, shrink fitting, or threading. Additionally, the polycrystalline diamond elements may be mounted in a separate ring or rings. The ring or rings may then be deployed on the bearing element (rotor or stator) via methods known in the art including, but not limited to, gluing, press fitting, thread locking, or brazing.

Planar face or domed polycrystalline diamond elements may be mounted in a manner to allow them to rotate about their own axis. Reference is made to <CIT>, as a non-limiting example of a method to allow the polycrystalline diamond element to spin about its own axis while in facial contact with subject material.

In some aspects, the opposing engaging surface of the diamond reactive material is pre-saturated with carbon (e.g., prior to engagement with the engagement surface). Such pre-saturation reduces the ability of the diamond reactive material to attract carbon through graphitization of the surface of the polycrystalline diamond. The pre-saturation of the diamond reactive material surface contact area may be accomplished via any method known in the art.

In certain applications, a solid lubricant source, for example, a graphite or hexagonal boron nitride stick or inclusion, either energized or not energized, is in contact with the opposing engagement surface formed of or including at least some the diamond reactive material. In some embodiments, the sliding engagement between engagement surface and opposing engagement surface is non-lubricated.

The present disclosure include drilling tools (e.g., motors) and components thereof, such as drive shafts and bearing housings, that include polycrystalline radial bearing assemblies thereon. As used herein, downhole tools and downhole drilling tools may be or include, but are not limited to, rotary steerable tools, turbines, jars, reamers, agitators, MWD tools, LWD tools, and drilling motors. Drill strings may include a number of segments, including drill piping or tubulars extending from the surface, a mud motor (i.e., a positive displacement progressive cavity mud powered motor) and a drill bit. The mud motor may include a rotor catch assembly, a power section, a transmission, a bearing package (bearing assembly), and a bit drive shaft with a bit box. The power section generally includes a stator housing connected to and part of the drill string, and a rotor. The radial bearings shown and described with reference to <FIG> may be incorporated into a such drilling motors (e.g., at the drive shaft and bearing housing). With reference to <FIG>, some embodiments include a bottom hole assembly (BHA) or a portion thereof, including assembly <NUM>. Assembly <NUM> includes rotor <NUM> movably coupled within a bore of stator <NUM>. Rotor <NUM> is coupled with transmission <NUM>, which is positioned and movably coupled within a bore of transmission housing <NUM>. Transmission <NUM> is coupled with drive shaft <NUM>, which is positioned and movably coupled within a bore of bearing housing <NUM>. Drive shaft <NUM> is coupled with bit shaft <NUM>, and bit shaft <NUM> is coupled with or integral with drill bit <NUM>. Stator <NUM> is coupled with transmission housing <NUM>, which is coupled with bearing housing <NUM>, which is coupled with shaft housing <NUM>. In operation, the mud motor (rotor <NUM> and stator <NUM>) is powered by energy harvested from drilling mud as the mud passes through the power section. The drilling mud is pumped at high pressures and volumes from the surface down the internal cavities of a drill string and through the power section. Mud passing through the power section rotates rotor <NUM> with respect to stator <NUM>. Rotor <NUM>, in-turn, drives rotation, through a transmission driveline (transmission <NUM>), drive shaft <NUM>, and bit shaft <NUM>, to drill bit <NUM>. Assembly <NUM> may be generally tubular, and may include one or more tubular subunits or subs to, for example and without limitation, facilitate assembly thereof. One having ordinary skill in the art with the benefit of this disclosure would understand that the specific sub arrangement of assembly <NUM> depicted and described herein is merely exemplary and is not intended to limit the scope of this disclosure. In some embodiments, assembly <NUM> includes one or more external stabilizers <NUM> to, for example and without limitation, position assembly <NUM> within a wellbore. External stabilizers <NUM> may be, for example and without limitation, one or more radial protrusions. External stabilizers <NUM> may be positioned and sized depending on the wellbore in which assembly <NUM> is to be used. While drive shaft <NUM> is shown as coupled with rotor <NUM> via transmission <NUM>, in some embodiments, drive shaft <NUM> is coupled directly to rotor <NUM>. Also, while drive shaft <NUM> is shown as coupled with drill bit <NUM> via bit shaft <NUM>, in some embodiments drive shaft <NUM> is coupled directly to drill bit <NUM>. <FIG> is a simplified schematic showing the basic arrangement and coupling between rotor <NUM>, drive shaft <NUM>, and drill bit <NUM>, such that rotor <NUM> drives shaft <NUM>, which in-turn drives bit <NUM>.

Drive shaft <NUM> is coupled with bearing housing <NUM> via one or more bearings <NUM>, which are or include polycrystalline diamond elements. In some embodiments, bearings <NUM> are radiused conical bearings, also referred to in the art as angle, taper, or cup/cone bearings, including cup portion <NUM> coupled with cone portion <NUM>. <FIG> depict more detailed views of radiused conical bearings. With reference to <FIG>, radiused conical bearing 1552a includes cup portion <NUM> and cone portion <NUM>. As shown in <FIG>, cone portion <NUM> includes bearing surface <NUM>. Bearing surface <NUM> has a plurality of polycrystalline diamond elements <NUM> thereon, and extending therefrom. Each polycrystalline diamond element <NUM> has an engagement surface <NUM>, and cup portion <NUM> has opposing engagement surface <NUM>. Cup portion <NUM> and cone portion <NUM> may be generally annular and configured to contact at engagement surfaces <NUM> and opposing engagement surface <NUM>. Bearing surface <NUM> and opposing engaging surface <NUM> may be generally frustoconical in shape, such that bearing 1552a resists longitudinal or thrust loading as well as resisting radial loading between cup portion <NUM> and cone portion <NUM>, while allowing relative rotation between cup portion <NUM> and cone portion <NUM>. As such, bearing 1552a may act as both a radial and thrust bearing. Opposing engagement surface <NUM> is or includes a diamond reactive material, such as steel. <FIG> depicts bearing 1552b, which is identical to bearing 1552a, with the exception that polycrystalline diamond elements <NUM> are positioned and extend from surface <NUM>, as opposed to surface <NUM>. In some embodiments, when engagement surfaces <NUM> are engaged with opposing engagement surface (<NUM> or <NUM>), less than an entirety of each engagement surface <NUM> is engaged with the opposing engagement surface. In some embodiments, less than <NUM>%, less than <NUM>%, less than <NUM>%, less than <NUM>%, less than <NUM>%, less than <NUM>%, or less than <NUM>% of a surface area of each engagement surface <NUM> is engaged with the opposing engagement surface. With reference to <FIG>, engagement surface <NUM> of polycrystalline diamond element <NUM> is shown, with contact area 1573a indicating the portion of the surface area of engagement surface <NUM> that would be in contact with the opposing engagement surface in a bearing assembly, with the remainder of contact area 1573b of engagement surface <NUM> not in contact with the opposing engagement surface. That is, contact area 1573a defines the area of contact of engagement surface <NUM> after a bearing load is applied thereto. The contact area 1573a is, of course, for exemplary purposes only and is only intended to illustrate that the contact area 1573a is less than an entirety of available surface area on engagement surface <NUM>. As shown, contact area 1573a may be or define a line contact or linear contact <NUM>, such that when engagement surface <NUM> is in sliding engagement with an opposing engagement surface, the sliding contact occurs along line contact <NUM>. In some embodiments, engagement surface <NUM> is in sliding engagement with an opposing engagement surface along contact area 1573a, the opposing engagement surface rotates about an axis of rotation, and any imaginary line extending from and normal to contact area <NUM> surface is at an angle relative to said axis of rotation. In some embodiments, engagement surface <NUM> is in sliding contact with an opposing engagement surface through a substantial portion of its use profile.

In some embodiments, the opposing engagement surface does not have any polycrystalline diamond elements or any other bearing elements, and is a single, continuous surface. In some such embodiments, the engagement surfaces are multiple, discrete, spaced-apart surfaces that are each positioned to engage with the same opposing engagement surface. When engaged, in operation, the multiple, discrete, spaced-apart engagement surfaces may maintain constant contact with the single continuous, opposing engagement surface. In some embodiments, the sliding engagement between the engagement surfaces and the opposing engagement surface is non-lubricated. In some embodiments, the drive shaft has a rotational velocity, the engagement between the engagement surface and opposing engagement surface defines a contact area, and the contact area is independent of the rotational velocity of the drive shaft. In some such embodiments, the drive shaft has a variable rotational velocity, and the engagement surfaces follow an engagement path on the opposing engagement surface that is constant through the variable rotational velocities.

With reference to <FIG>, the cup portion shown and described in <FIG> may be a portion of bearing housing <NUM>, and the cone portion may be a portion of drive shaft <NUM>.

With reference to <FIG>, bearings 1452a and 1452b may be positioned such that bearings 1452a and 1452b retain drive shaft <NUM> both longitudinally and radially. In some embodiments, bearings 1452a and 1452b may be oriented in opposing directions, as shown by mounting orientations 1463a and 1463b. Although described herein as utilizing two bearings 1452a and 1452b, one having ordinary skill in the art with the benefit of this disclosure would understand that any number of bearings may be utilized without deviating from the scope of this disclosure. <FIG> also depicts the effective bearing spread <NUM>.

<FIG> depict portions of a drill string assembly without the outer housing thereon, including transmission <NUM>, drive shaft <NUM>, bit shaft <NUM>, and drill bit <NUM>. Drive shaft <NUM> includes cone portions <NUM>, each engaged with a plurality of polycrystalline diamond elements <NUM>. While not shown, the polycrystalline diamond elements <NUM> are coupled on a cup portion of a bearing housing (not shown) surrounding drive shaft <NUM>, which may be the same as that shown in <FIG>, and are positioned on the bearing housing such that the polycrystalline diamond elements <NUM> engaged with drive shaft <NUM>. Each polycrystalline diamond element <NUM> includes an engagement surface <NUM>, for engagement with an opposing engagement surface of cone portions <NUM>. As shown in <FIG>, the bearing element spacing <NUM> between adjacent polycrystalline diamond elements <NUM> is relatively narrow. As used herein, "bearing element spacing" refers to the distance between adjacent polycrystalline diamond elements. In some embodiments, the bearing element spacing <NUM> is sufficiently narrow, such that bearing element spacing <NUM> is less than a width <NUM> of each adjacent polycrystalline diamond element <NUM>.

<FIG> depict portions of a drill string assembly without the outer housing thereon. The portion of the drill string assembly shown in <FIG> is identical to that of <FIG>, with the exception that the bearing element spacing in <FIG> is greater than the bearing element spacing in <FIG>. The drill string assembly shown in <FIG> includes transmission <NUM>, drive shaft <NUM>, bit shaft <NUM>, and drill bit <NUM>. Drive shaft <NUM> includes cone portions <NUM> engaged with a plurality of polycrystalline diamond elements <NUM>, which are coupled on cup portion of a bearing housing (not shown), which may be the same as the bearing housing (<NUM>) shown in <FIG>. Each polycrystalline diamond element <NUM> includes an engagement surface <NUM>, for engagement with an opposing engagement surface of cone portions <NUM>. As shown in <FIG>, the bearing element spacing <NUM> between adjacent polycrystalline diamond elements <NUM> is wide relative to that of <FIG>. In some embodiments, the bearing element spacing <NUM> is sufficiently wide, such that bearing element spacing <NUM> is greater than a width <NUM> of each adjacent polycrystalline diamond element <NUM>. In some embodiments, bearing element spacing <NUM> is at least <NUM>%, at least <NUM>%, at least <NUM>%, at least <NUM>%, at least <NUM>%, or at least <NUM>% greater than width <NUM>.

<FIG> depict portions of the drive shaft and bearing elements thereof. Drive shaft <NUM> is engaged with, at cup portion <NUM>, a plurality of polycrystalline diamond elements <NUM>. Each polycrystalline diamond element <NUM> has an engagement surface <NUM>, is supported via supports <NUM> (e.g., tungsten carbide), and is coupled on a cone portion of a bearing housing, <NUM>, which may be the same as the bearing housing (<NUM>) shown in <FIG>. As shown, each engagement surface <NUM> is planar. As shown in <FIG>, edge contact between the polycrystalline diamond and drive shaft <NUM> is avoided.

<FIG> is a cross-sectional view of a portion of a drill string assembly substantially identical to that of <FIG>, with the exception that the drive shaft has a bearing ring positioned thereabout.

Bearing ring <NUM> is coupled about the outer circumference of drive shaft <NUM>, at cup portion <NUM> of drive shaft <NUM>. Bearing ring <NUM> may be composed of the same material as drive shaft <NUM>, or may be composed of a different material than drive shaft <NUM>. In some embodiments bearing ring <NUM> is composed of a material that has higher wear-resistance than the material that drive shaft <NUM> is composed of. Bearing ring <NUM> includes or defines opposing engagement surface <NUM> for engagement with diamond engagement surface <NUM>. In some embodiments, bearing ring <NUM> is replaceable, such that after a certain degree of wear to bearing ring <NUM>, bearing ring <NUM> may be removed from drive shaft <NUM> and a new and/or replacement bearing ring <NUM> may then be coupled onto drive shaft <NUM>. Thus, the use of bearing ring <NUM> may increase the usable lifetime of drive shaft <NUM> because the wear only or mostly occurs on the replaceable bearing ring <NUM> and not on drive shaft <NUM>. Bearing ring <NUM> may encircle drive shaft <NUM>. Bearing ring <NUM> is not limited to the shape shown in <FIG>. While the bearing ring is shown and described as being coupled about the drive shaft and positioned for engagement with the polycrystalline diamond elements that are on the bearing housing, the bearing assembly disclosed herein is not limited to this particular arrangement. For example, the bearing ring may be coupled about an inner surface of the bearing housing and positioned for engagement with the polycrystalline diamond elements that are on the outer surface of the drive shaft.

As shown in <FIG>, the cone component, or a portion thereof, of the conical bearing assemblies can be discrete. That is, in some embodiments the cone component, or a portion thereof, is not integral with the mandrel or drive shaft, but is a discrete component that is coupled therewith. Such an arrangement provides for the opposing engagement surface to have selected or engineered properties that are different from that of the mandrel or drive shaft (e.g., being composed of a different material composition). Such selected or engineered properties may include superior performance properties, such as higher wear-resistance properties in comparison to the mandrel or drive shaft surface. Also, such an arrangement, in some embodiments, provides for ease of repair and replacement, as well as a lower cost for repair and replacement.

<FIG> is a cross-sectional view of a portion of a drill string assembly substantially identical to that of <FIG>, with the exception that the drive shaft and bearing housing each have a bearing ring positioned thereabout. As shown in <FIG>, both the cup and cone components of the conical bearing assemblies disclosed herein can be discrete components. That is, drive shaft <NUM> includes bearing ring 1899a coupled thereabout (i.e., not integral with the drive shaft). Also, bearing housing <NUM> includes bearing ring 1899b coupled therewith, and not integral therewith. Polycrystalline diamond element <NUM> is coupled with bearing ring 1899b, and includes diamond engagement surface <NUM> engaged with opposing engagement surface <NUM> of bearing ring 1899a.

While the polycrystalline diamond element is shown and described as coupled with bearing ring 1899b on bearing housing <NUM> in <FIG>, in other embodiments the polycrystalline diamond elements are coupled with bearing ring 1899a on drive shaft <NUM>, such that the diamond engagement surface of the polycrystalline diamond elements engage with an opposing engagement surface of bearing ring 1899b (or of bearing housing <NUM>, in embodiments where bearing ring 1899b is not used). In some embodiments, the polycrystalline diamond elements are coupled with the drive shaft <NUM> (when bearing ring 1899a is not used), and the polycrystalline diamond elements are engaged with an opposing engagement surface of bearing ring 1899b (or of bearing housing <NUM>, in embodiments where bearing ring 1899b is not used).

In some embodiments, the bearing ring, the bearing housing, the drive shaft, or combinations thereof are composed, at least partially, of a "hardened material" as defined in <CIT>.

The bearing rings disclosed herein, including the embodiments shown in <FIG>, can be used as sacrificial surfaces and/or components. That is, the bearing rings can be used to bear loads such that the surfaces of the bearing rings are worn. Worn bearing rings can be then be replaced without having to replace an entirety of the bearing assembly. Thus, in some embodiments, the bearing rings can provide for easier and more cost-effective repair and/or replacement of the bearing assemblies disclosed herein.

In some embodiments, the additional space on the drive shaft and/or in the bearing housing that is available due to increased spatial distance between adjacent polycrystalline diamond elements is utilized to deploy one or more additional downhole components on the drill string assembly. For example, in a drive shaft in accordance with <FIG>, space <NUM> between adjacent polycrystalline diamond elements may be used to deploy additional downhole components on or within the associated bearing housing.

With reference to <FIG>, drive shaft <NUM> is depicted engaged with a plurality of polycrystalline diamond elements <NUM>, which are coupled with a bearing housing (not shown) that is the same or similar to the bearing housing (<NUM>) shown in <FIG>. Spaces <NUM>, positioned between adjacent polycrystalline diamond elements <NUM>, may accommodate downhole components <NUM>. While downhole components <NUM> are shown positioned between each set of adjacent polycrystalline diamond elements <NUM>, the drive shafts disclosed herein are not limited to including a downhole component between each set of adjacent polycrystalline diamond elements. In some embodiments, at least one space between adjacent polycrystalline diamond elements lacks a downhole component. In some embodiments, at least one space between adjacent polycrystalline diamond elements includes multiple downhole components. The downhole components may be embedded in, attached to, or otherwise coupled with the bearing housing. By incorporating downhole components where there would otherwise be bearing elements (e.g., polycrystalline diamond elements) or empty space, the available space on the bearing housing is more efficiently utilized. As such, the bearing housing may be incorporated with additional functionalities and capabilities that would otherwise not be available, or at least would otherwise occupy additional surface area on the bearing housing or other part of the drill string assembly. That is, spacing the polycrystalline diamond elements apart provides additional surface area on the drill string assembly that would otherwise not be available for use; thereby, increasing the potential functionality of the bearing housing and utilization of the space thereon. Each of the plurality of downhole components <NUM> may be the same, or the plurality of downhole components <NUM> may include multiple different downhole components. Each downhole component <NUM> may be or include a mechanical downhole component, an electromechanical downhole component, a sensor, communication components, or recording components. For example, and without limitation, each downhole component <NUM> may be or include a mechanical or electromechanical downhole component, such as a dynamic lateral pad (DLP), a dynamic lateral cutter (DLC), a mandrel driven generator, one or more batteries, an actuator, an extendable sensor (e.g., a sensor in face of a DLP), an extendable reamer blade, a caliper, or a rotary electrical connection, such as a slip ring, a rotary union, or a fiber optic rotary joint. Each downhole component <NUM> may be or include a sensor, such as an azimuth sensor (gyroscope), an inclination sensor (inclinometer, gyroscope, magnometer), an accelerometer (to measure vibrations), an acoustic sensor, a gamma ray sensor (e.g., a scintillation crystal), a density sensor (deinsimeter), a resistivity sensor (electrodes, current generator), a temperature sensor (thermocouple), a pressure sensor (pressure transducers), a magnetic field sensor, a torque sensor, a weight on bit (WOB) sensor, a bending moments sensor (strain gage), an RPM sensor (e.g., accelerometers, tachometers), a linear displacement sensor (e.g., for use with calipers, pads), such as a linear variable differential transformer (LVDT) sensor, a porosity, lithology, permeability or rock strength sensor (e.g., piezoelectric transducers and receivers, such as for sonic and ultrasonic components, or a nuclear magnetic resonance sensor. Each downhole component <NUM> may be or include a communication and/or recording component, such as a pulser, a data storage, a transmitter, or a microprocessor. As used herein DLPs and DLCs are those shown and described in <CIT>.

In some embodiments, the spacing between adjacent polycrystalline diamond elements can be selected and/or determined such that a desired downhole component can be positioned therein. For example, if it is know that a temperature sensor of a particular size is needed, the bearing assembly can be designed such that at least one spacing between two adjacent polycrystalline diamond elements is of sufficient size that the temperature sensor can be positioned therein, while still attaining sufficient bearing capacity for the particular drilling operation. Thus, in some embodiments the number of polycrystalline diamond elements in the bearing assembly is not maximized but is, instead, designed to be sufficient to bear expected load while also being spaced apart enough to provide space for additional downhole components. In some embodiments, adjacent polycrystalline diamond elements are spaced apart on the conical radial bearing to provide axial space on the drill string that would otherwise not be available for downhole components. In some embodiments, additional space for placement of downhole components on the drill string is formed by maintaining a standard bit-to-bend length while also using the bearing technology disclosed herein (e.g., having spaced apart adjacent polycrystalline diamond elements in accordance with <FIG>) that only requires a portion of the standard bit-to-bend length. That is, the additional unneeded bit-to-bend length may be utilized for incorporation of additional downhole components onto the drill string.

<FIG> depicts additional space <NUM> on bearing housing <NUM> that may be available when using the conical bearing assemblies disclosed herein, with polycrystalline diamond elements <NUM> arranged in a spaced-apart configuration, such as is shown in <FIG>. <FIG> is identical to <FIG>, with the exception that additional downhole components 2000a and 2000b are positioned in additional spaces <NUM>.

In some embodiments, the bearings disclosed herein may be sealed bearing packages. In other embodiments, the bearings disclosed herein may be unsealed bearing package.

One skilled in the art would understand that the drill string assembly and drilling motor disclosed herein is not limited to the particular arrangement of parts shown and described with reference to <FIG>. For example, while the drive shaft is described as being connected with the rotor, the drive shaft may be integral with and an extension of the rotor. Also, the drill bit is described as being connected with the drive shaft, the drill bit or a portion thereof may be integral with and an extension of the drive shaft.

One skilled in the art would understand that the features shown and described with respect to <FIG> with respect to rotors and stators can be combined with and/or applied to the drive shaft and bearing housing assembly described with reference to <FIG>. For example, the same or similar polycrystalline diamond elements may be used, and may be mounted in the same or similar way. Also, a drive shaft and bearing housing in accordance with <FIG> may be coupled with a rotor and stator in accordance with <FIG>.

In some embodiments, the bearing housing functions as an antenna for communication between the downhole components incorporated into or on the bearing housing and other components, such as other downhole components or surface components at the surface (i.e., not downhole). For example, the bearing housing, or a portion thereof, may be composed of an electrically conductive material that is capable of transmitting data signals to and/or from downhole components, such as a copper alloy. For example, the downhole components incorporated into or on the bearing housing may include a sensor that is coupled with the bearing housing such that sensor measurement data from sensor may be transmitted along bearing housing, or a portion thereof, when bearing housing is configured to function as an antenna.

The bearing assemblies disclosed herein may form a portion of a machine or other apparatus or system. In some such aspects, the proximal end of the stator may be connected to another component, such as a drill string or motor housing by threaded connection, welding, or other connection means as known in the art. In some aspects, if the bearing assembly is used in a downhole application, the distal end of the rotor may be augmented by a thrust bearing and may carry a threaded connection for the attachment of a drill bit, or the distal end of the rotor may be a drill bit directly formed on and/or positioned on the end of the mandrel of the rotor. The component connections are not limited to downhole applications, and can be applied to other applications, for example wind turbine energy generators, or marine applications.

Furthermore, discrete versions of the bearing assemblies described herein may be used in a broad array of other applications including, but not limited to, heavy equipment, automotive, turbines, transmissions, rail cars, computer hard drives, centrifuges, medical equipment, pumps, and motors.

In certain aspects, the bearing assemblies disclosed herein are suitable for deployment and use in harsh environments (e.g., downhole). In some such aspects, the bearing assemblies are less susceptible to fracture than bearing assemblies where a polycrystalline diamond engagement surface engages with another polycrystalline diamond engagement surface. In certain aspects, such harsh environment suitable radial bearings provide enhanced service value in comparison with bearing assemblies that include a polycrystalline diamond engagement surface engaged with another polycrystalline diamond engagement surface. Furthermore, the bearing assemblies disclosed herein may be capable of being spaced apart at greater distances that the spacings required when using bearing assemblies that include a polycrystalline diamond engagement surface engaged with another polycrystalline diamond engagement surface.

In certain applications, the bearing assemblies disclosed herein can act as a rotor catch, such as in downhole applications.

In lubricated environments, the bearing assemblies may benefit from the hydrodynamic effect of the lubricant creating a clearance between the moving and stationary elements of the bearing assembly.

In an effort to develop a robust cam follower interface for use in Applicants' previously referenced "Drilling Machine" of <CIT> (the '<NUM> Application), Applicants designed and constructed an advanced test bench. The test bench employed a <NUM> RPM electric gearmotor driving a hard-faced ferrous rotor mandrel inside a hard-faced ferrous stator housing. The mandrel incorporated a non-hard faced offset camming cylinder midway along its length. The rotor/stator assembly was fed a circulating fluid through the use of a positive displacement pump. Candidate cam follower interface mechanisms were placed in contact and under load with the camming cylinder of the rotor mandrel. Employing the test bench, candidate interface mechanisms were tested for survivability and wear under loads ranging from <NUM> to <NUM> lbf (<NUM> to <NUM> N) either in clear water or in sand laden drilling fluid.

The Applicants conducted testing of the ferrous camming cylinder in sliding contact with polished polycrystalline diamond surfaces without deleterious effects or apparent chemical interaction. Ferrous materials are attractive for bearing applications due to their ready availability, ease of forming and machining, higher elasticity, and lower cost than so called superhard materials.

The testing program conducted by the Applicants has established that, even at relatively high loads and high RPM speeds, a successful load interface between polycrystalline diamond and diamond reactive materials can be employed in bearing applications.

A key finding has been that, as long as polycrystalline diamond elements are not put into edge or point contact with diamond reactive materials, which, it is believed, could lead to machining and chemical interaction, the polycrystalline diamond can experience sliding contact with diamond reactive materials at the typical bearing loads and speeds called for in many applications. This unexpected and surprising success of the Applicants' testing has led to the development of new high performance radial bearings.

The testing program included tests of a curved ferrous surface in high load facial linear area contact with planar polycrystalline diamond under rotation. This testing produced a slightly discolored Hertzian contact area on the face of the PDC about <NUM>" (<NUM>) in width along the entire ½"(<NUM>) wide face of the polycrystalline diamond. The width of the contact area can be explained by the cam offset, vibration in the system and by slight deformation of the ferrous metal under load. It is estimated that the total contact area on the ½" (<NUM>) polycrystalline diamond element face, at any given point in time, is about <NUM>%, or less, of the total area of the polycrystalline diamond element face. The configuration employed in the testing demonstrates that even a small surface area on the face of a polycrystalline diamond element can take significant load.

Additional testing of a spherical ferrous ball under load and rotation against a planar polycrystalline diamond face produced a small, approximately <NUM> diameter, discolored Hertzian contact area in the center of the polycrystalline diamond element. As in the contact explanation above, it is believed, without being bound by theory, that the diameter of the discoloration is a result of slight vibration in the test apparatus and by slight deformation of the ferrous metal under load.

Tests <NUM> and <NUM> summarize failed tests of individual steel balls rolling in a steel cup under load. Test <NUM> summarizes the results of a more successful test of a steel ball supported by a single polished PDC element in a steel cup. Test <NUM> summarizes a very successful test of a single steel ball supported by an array of three polished polycrystalline diamond elements in a steel cup. Tests <NUM> through <NUM> summarize increasingly rigorous tests each of a single polished polycrystalline diamond element in sliding contact with a rotating ferrous cam surface. Test <NUM> summarizes a comparative test of a single polished polycrystalline diamond element versus a single unpolished polycrystalline diamond element, each in sliding contact with a rotating ferrous cam surface. The final test shows a significant increase in coefficient of friction when the unpolished polycrystalline diamond element was used. The conditions and results presented in Table <NUM> are emblematic of the potential use of polycrystalline diamond on diamond reactive material and are not to be considered limiting or fully encompassing of the technology of the application.

It was found that applications of polycrystalline diamond elements in a radial bearing can employ far less than the full face of the elements and still take significant load. This finding means effective polycrystalline diamond element containing radial bearings can be designed and manufactured without the need for full face contact of the polycrystalline diamond elements with the opposing surface. Employing this finding in the technology of the present application means it is possible to manufacture radial bearings with far less processing of the polycrystalline diamond elements used and substantially reducing the risk of edge clashing, or of the instigation of machining of a diamond reactive material opposing surface.

Without being bound by theory, in operation, running a cam and cam follower in a liquid cooled, lubricated environment, allows for higher speeds and loads to be attained without commencing a thermo-chemical reaction. Further, a polycrystalline diamond face that has been polished, notably, provides a lower thermo-chemical response.

From the descriptions and figures provided above it can readily be understood that the bearing assembly technology of the present application may be employed in a broad spectrum of applications, including those in downhole environments. The technology provided herein additionally has broad application to other industrial applications.

Furthermore, while shown and described in relation to engagement between surfaces in a radial bearing assembly, one skilled in the art would understand that the present disclosure is not limited to this particular application and that the concepts disclosed herein may be applied to the engagement between any diamond reactive material surface that is engaged with the surface of a diamond material.

Claim 1:
A downhole tool for use in a downhole drill string, the downhole tool comprising:
a drive shaft (<NUM>, <NUM>, <NUM>) movably coupled within a bearing housing (<NUM>, <NUM>, <NUM>), wherein the drive shaft (<NUM>, <NUM>, <NUM>) has a first end and a second end;
a rotor (<NUM>) coupled with the second end of the drive shaft (<NUM>, <NUM>, <NUM>);
a stator (<NUM>) coupled with the rotor (<NUM>); and
a bearing assembly (<NUM>) interfacing engagement between the drive shaft (<NUM>, <NUM>, <NUM>) and the bearing housing (<NUM>, <NUM>, <NUM>), the bearing assembly comprising:
a plurality of spaced-apart polycrystalline diamond elements (<NUM>, <NUM>, <NUM>), wherein each polycrystalline diamond elements (<NUM>, <NUM>, <NUM>) has an engagement surface (<NUM>, <NUM>); and
an opposing engagement surface (<NUM>, <NUM>, <NUM>) comprising a metal, the metal comprising at least <NUM> wt.% of a diamond catalyst or diamond solvent based on a total weight of the metal, wherein the opposing engagement surface (<NUM>, <NUM>, <NUM>) is movably engaged with each of the engagement surfaces (<NUM>, <NUM>);
wherein the plurality of polycrystalline diamond elements (<NUM>, <NUM>) are coupled with the drive shaft (<NUM>, <NUM>) and the opposing engagement surface (<NUM>) is a surface on the bearing housing (<NUM>, <NUM>), or wherein the plurality of polycrystalline diamond elements (<NUM>, <NUM>, <NUM>) are coupled with the bearing housing (<NUM>, <NUM>, <NUM>) and the opposing engagement surface (<NUM>) is a surface on the drive shaft (<NUM>, <NUM>, <NUM>).