U.S. patent application number 16/269859 was filed with the patent office on 2019-06-06 for bearing apparatus including a bearing assembly having a continuous bearing element and a tilting pad bearing assembly.
The applicant listed for this patent is US SYNTHETIC CORPORATION, WAUKESHA BEARINGS CORPORATION. Invention is credited to Jair J. Gonzalez, Leonidas C. Leite, Sriram Venkatesan.
Application Number | 20190170186 16/269859 |
Document ID | / |
Family ID | 56092266 |
Filed Date | 2019-06-06 |
United States Patent
Application |
20190170186 |
Kind Code |
A1 |
Gonzalez; Jair J. ; et
al. |
June 6, 2019 |
BEARING APPARATUS INCLUDING A BEARING ASSEMBLY HAVING A CONTINUOUS
BEARING ELEMENT AND A TILTING PAD BEARING ASSEMBLY
Abstract
Embodiments of the invention relate to 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 2 inches.
Inventors: |
Gonzalez; Jair J.; (Provo,
UT) ; Leite; Leonidas C.; (Provo, UT) ;
Venkatesan; Sriram; (Waukesha, WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
US SYNTHETIC CORPORATION
WAUKESHA BEARINGS CORPORATION |
Orem
Pewaukee |
UT
WI |
US
US |
|
|
Family ID: |
56092266 |
Appl. No.: |
16/269859 |
Filed: |
February 7, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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15528709 |
May 22, 2017 |
10240631 |
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PCT/US15/62434 |
Nov 24, 2015 |
|
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16269859 |
|
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62087132 |
Dec 3, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16C 2206/60 20130101;
F16C 2206/04 20130101; F16C 2206/58 20130101; F16C 2206/82
20130101; F16C 2352/00 20130101; F16C 17/035 20130101; F16C 2206/56
20130101; F16C 17/065 20130101; F16C 33/043 20130101 |
International
Class: |
F16C 17/06 20060101
F16C017/06; F16C 33/04 20060101 F16C033/04; F16C 17/03 20060101
F16C017/03 |
Claims
1. A bearing apparatus, comprising a first bearing assembly
including: a first support ring; and a plurality of tilting pads
each of which includes a superhard bearing element having a
superhard bearing surface, each of the plurality of tilting pads
tilted and/or tiltably secured relative to the first support ring;
and a second bearing assembly including: a continuous superhard
bearing element including a continuous superhard bearing surface
that generally faces the superhard bearing element of each of the
plurality of tilting pads, the continuous superhard bearing element
having a maximum lateral width greater than about 12.7 cm.
2. The bearing apparatus of claim 1 wherein the superhard bearing
surface of at least one of the plurality of tilting pads includes
at least one of polycrystalline diamond, silicon carbide, silicon
nitride, cubic boron nitride, tantalum carbide, reaction-bonded
silicon carbide, reaction-bonded silicon nitride, or binderless
tungsten carbide.
3. The bearing apparatus of claim 1 wherein the maximum lateral
width is about 12.7 cm to about 30.5 cm.
4. The bearing apparatus of claim 1 wherein the maximum lateral
width is about 12.7 cm to about 17.8 cm.
5. The bearing apparatus of claim 1 wherein the maximum lateral
width is about 17.8 cm to about 25.4 cm.
6. The bearing apparatus of claim 1 wherein the continuous
superhard bearing element includes a superhard table bonded to a
substrate.
7. The bearing apparatus of claim 6 wherein the superhard table
includes polycrystalline diamond.
8. The bearing apparatus of claim 1 wherein the continuous
superhard bearing surface includes at least one of silicon carbide
or silicon nitride.
9. The bearing apparatus of claim 8 wherein the continuous
superhard bearing surface includes at least one additional material
added to the silicon carbide or silicon nitride, the at least one
additional material including at least one of diamond or boron
carbide.
10. The bearing apparatus of claim 9 wherein the at least one
additional material is added to the silicon carbide or silicon
nitride in an amount less than about 80 weight %.
11. The bearing apparatus of claim 1 wherein the continuous
superhard bearing surface of the continuous superhard bearing
element and the superhard bearing surface of at least one of the
plurality of tilting pads comprise different materials.
12. The bearing apparatus of claim 1 wherein the continuous
superhard bearing surface of the continuous superhard bearing
element includes silicon carbide and the superhard bearing surface
of at least one of the plurality of tilting pads includes
polycrystalline diamond.
13. The bearing apparatus of claim 1 wherein at least one of the
superhard bearing surface of at least one of the plurality of
tilting pads or the continuous superhard bearing element includes a
coating.
14. The bearing apparatus of claim 1 wherein at least one the
continuous superhard bearing surface of the continuous superhard
bearing element or the superhard bearing surface of at least one of
the plurality of tilting pads has a surface finish of less than
about 0.89 .mu.m.
15. The bearing apparatus of claim 14 wherein the surface finish is
about 0.13 .mu.m to about 0.25 .mu.m.
16. The bearing apparatus of claim 13 wherein the surface finish is
less than about 0.064 .mu.m.
17. The bearing apparatus of claim 1 wherein the continuous
superhard bearing element is brazed to the second support ring.
18. The bearing apparatus of claim 1 wherein the first bearing
assembly is a stator and the second bearing assembly is a
rotor.
19. A method of operating a bearing apparatus, the method
comprising: rotating a rotor relative to a stator; wherein at least
one of the stator or the rotor includes: a first support ring; and
a plurality of tilting pads each of which includes a superhard
bearing element having a superhard bearing surface, each of the
plurality of tilting pads tilted and/or tiltably secured relative
to the first support ring; wherein the other of the stator or rotor
includes: a continuous superhard bearing element including a
continuous superhard bearing surface that generally faces superhard
bearing element of each of the plurality of tilting pads, the
continuous superhard bearing element having a maximum lateral width
greater than about 12.7 cm.
20. A method for manufacturing a bearing assembly, the method
comprising forming a continuous superhard bearing element that
includes a continuous superhard bearing surface, the continuous
superhard bearing element having a maximum lateral width greater
than about 12.7 cm; forming a hole in the center of the continuous
superhard bearing element; providing a support ring including a
recess configured to receive the continuous superhard bearing
element; attaching the continuous superhard bearing element to the
support ring such that the continuous superhard bearing element is
secured in the recess of the support ring and the continuous
superhard bearing element; and smoothing the continuous superhard
bearing surface of the continuous superhard bearing element to
exhibit a surface finish of less than 0.64 .mu.m.
21. The method of claim 20 wherein forming a continuous superhard
bearing element that includes a continuous superhard bearing
surface includes forming the continuous superhard bearing surface
from a polycrystalline diamond table that is bonded to a substrate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/528,709 filed on May 22, 2017, which is a
U.S. national stage application of PCT Application No.
PCT/US2015/062434 filed on Nov. 24, 2015, which claims priority to
U.S. Provisional Application No. 62/087,132 filed on Dec. 3, 2014,
the disclosure of each of which is incorporated herein, in its
entirety, by this reference.
BACKGROUND
[0002] Wear-resistant, superhard compacts are utilized in a variety
of mechanical applications. For example, polycrystalline diamond
compacts ("PDCs") are used in drilling tools (e.g., cutting
elements, gage trimmers, etc.), machining equipment, bearing
apparatuses, wire-drawing machinery, and in other mechanical
apparatuses.
[0003] PDCs and other superhard compacts have found particular
utility as superhard bearing elements in thrust bearings within
pumps, turbines, subterranean drilling systems, motors,
compressors, generators, gearboxes, and other systems and
apparatuses. For example, a PDC bearing element typically includes
a superhard polycrystalline diamond layer that is commonly referred
to as a diamond table. The diamond table is formed and bonded to a
substrate using a high-pressure/high-temperature ("HPHT")
process.
[0004] A thrust-bearing apparatus includes a number of superhard
bearing elements affixed to a support ring. The superhard bearing
elements (e.g., a PDC bearing element) bear against other superhard
bearing elements of an adjacent bearing assembly during use.
Superhard bearing elements are typically brazed directly into a
preformed recess formed in a support ring of a fixed-position
thrust bearing.
[0005] Despite the availability of a number of different bearing
apparatuses including such PDCs and/or other superhard materials,
manufacturers and users of bearing apparatuses continue to seek
bearing apparatuses that exhibit improved performance
characteristics, lower cost, or both.
SUMMARY
[0006] Embodiments of the invention relate to bearing assemblies
and apparatuses, which may be operated hydrodynamically. The
disclosed bearing assemblies and apparatuses may be employed in
bearing apparatuses for use in pumps, turbines, compressors, turbo
expanders, or other mechanical systems.
[0007] In an embodiment, a bearing apparatus includes a first
bearing assembly and a second bearing assembly. The first bearing
assembly includes a first support ring and a plurality of tilting
pads each of which includes a superhard bearing surface. 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 generally facing
the superhard bearing surface of each of the tilting pads.
Additionally, the continuous superhard bearing element has a
maximum lateral width greater than 5.1 cm (about 2 inches).
[0008] In an embodiment, the continuous superhard bearing element
or a superhard bearing element of at least one tilting pad may
include polycrystalline diamond, or a sintered or reaction-bonded
ceramic (e.g., reaction-bonded silicon carbide or reaction-bonded
silicon nitride). In an embodiment, the continuous superhard
bearing element or a superhard bearing element of at least one
tilting pad may have a surface finish less than about 0.64
micrometers (.mu.m) (about 25 microinches).
[0009] Other embodiments are related to methods of using and
manufacturing bearing apparatuses including a first bearing
assembly having a plurality of tilting pads and a second bearing
assembly having a continuous superhard bearing element.
[0010] Features from any of the disclosed embodiments may be used
in combination with one another, without limitation. In addition,
other features and advantages of the present disclosure will become
apparent to those of ordinary skill in the art through
consideration of the following detailed description and the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The drawings illustrate several embodiments of the present
disclosure, wherein identical reference numerals refer to identical
or similar elements or features in different views or embodiments
shown in the drawings.
[0012] FIG. 1A is an isometric view of a bearing assembly including
continuous superhard bearing element having a continuous superhard
bearing surface according to an embodiment.
[0013] FIG. 1B is an isometric partial cross-sectional view taken
along the line 1B-1B of the bearing assembly of FIG. 1A.
[0014] FIG. 2A is an isometric view of a tilting pad thrust-bearing
assembly according to an embodiment.
[0015] FIG. 2B is an isometric partial cross-sectional view taken
along line 2B-2B of the tilting pad thrust-bearing assembly shown
in FIG. 2A.
[0016] FIG. 2C is an isometric view of one of the tilting pads
shown in FIGS. 2A and 2B, with the tilting pad having a continuous
superhard bearing surface according to an embodiment.
[0017] FIG. 2D is a cross-sectional view taken along line 2D-2D of
the bearing tilting pad shown in FIG. 2C.
[0018] FIG. 3 is a top plan view of a tilting pad including
multiple segments having serrated ends that form seams between the
multiple segments according to another embodiment.
[0019] FIG. 4 is an isometric view of a tilting pad comprising a
continuous superhard bearing element according to another
embodiment.
[0020] FIG. 5A is an isometric cutaway view of an embodiment of a
thrust-bearing apparatus that may include a rotor having continuous
superhard bearing element and a stator including tilting pads, with
a housing shown in cross-section.
[0021] FIG. 5B is a partial cross-sectional schematic
representation of the thrust-bearing apparatus of FIG. 5A during
use taken along line 5B-5B thereof showing a fluid film that
develops between the tilting pads of the stator and the continuous
superhard bearing element of the rotor.
[0022] FIG. 6A is an exploded isometric view of a radial bearing
apparatus that may include a rotor having a continuous superhard
bearing element and a stator including tilting pads according to an
embodiment.
[0023] FIG. 6B is an isometric partial cross-sectional view of the
stator of the radial bearing apparatus of FIG. 6A according to an
embodiment.
[0024] FIG. 6C is an isometric partial cross-sectional view of the
rotor of the radial bearing apparatus of FIG. 6A according to an
embodiment.
[0025] FIG. 7 is a partial isometric cutaway view of a rotary
system of a turbine according to an embodiment.
DETAILED DESCRIPTION
[0026] Embodiments of the invention relate to bearing assemblies
and apparatuses, which may be operated hydrodynamically. The
disclosed bearing assemblies and apparatuses may be employed in
bearing apparatuses for use in pumps, turbines, compressors, turbo
expanders, or other mechanical systems. Motor assemblies including
at least one of such bearing assemblies or apparatus are also
disclosed, as well as methods of using and fabricating such bearing
assemblies and apparatuses utilizing superhard materials.
[0027] As will be discussed in more detail below, in one or more
embodiments, a bearing apparatus includes a first bearing assembly
and a second bearing assembly. The first bearing assembly includes
a first support ring and a plurality of tilting pads each of which
includes a superhard bearing surface. Each tilting pad is tilted
and/or tiltably secured relative to the first support ring. The
second bearing assembly includes a second support ring and a
continuous superhard bearing element that is secured to the second
support ring. The continuous superhard bearing element includes a
continuous superhard bearing surface generally facing the superhard
bearing surface of each of the tilting pads. In some embodiments,
the continuous superhard bearing element has a maximum lateral
width greater than about 5.1 cm (about 2 inches).
[0028] While the description herein provides examples relative to a
pump or turbine bearing apparatus, the bearing assembly and
apparatus embodiments disclosed herein may be used in any number of
applications. For instance, the bearing assemblies and apparatuses
may be used in subterranean drilling and motor assembly, motors,
compressors, turbo expanders, generators, gearboxes, other systems
and apparatuses, or combinations of the foregoing. Furthermore, the
bearing assemblies and apparatuses may also be operated
hydrodynamically, partially hydrodynamically, or not
hydrodynamically, if desired or needed.
[0029] FIGS. 1A and 1B are isometric and isometric partial
cross-sectional views, respectively, of a thrust-bearing assembly
100 including a continuous superhard bearing element 102 having a
continuous superhard bearing surface 104. Such a configuration may
improve wear performance as compared to an assembly in which the
overall bearing surface is formed of a plurality of segmented,
discontinuous bearing surfaces defined by the individual bearing
elements. Additionally, such a configuration may improve wear
performance and manufacturing costs as compared to an assembly in
which the overall bearing surface is formed of a plurality of
segmented bearing elements that form a substantially continuous
bearing surface. Wear performance may be improved because the
substantial absence of any discontinuities in the overall bearing
surface may minimize and/or prevent chipping and/or cracking of the
continuous bearing surface 104, promote fluid film development
and/or prevent fluid from leaking through seams formed between
adjacent superhard bearing segments, increase fluid film strength,
or combinations thereof.
[0030] The continuous superhard bearing element 102 includes a
continuous superhard bearing surface 104. The continuous superhard
bearing surface 104 has an integral construction such that a single
superhard bearing element forms the full continuous superhard
bearing surface 104. The continuous superhard bearing element 102
is attached to a support ring 106 in a fixed position. For example,
the support ring 106 may define a recess 114 that receives the
continuous superhard bearing element 102 partially therein. The
continuous superhard bearing element 102 may be secured within the
recess 114 to the support ring 106 by brazing, press-fitting, using
fasteners, clamping, other type of mechanical attachment, another
suitable technique, or combinations thereof. However, in other
embodiments, the support ring 106 may be omitted.
[0031] The support ring 106 may be made from a variety of different
materials. For example, the support ring 106 may comprise carbon
steel, stainless steel, copper (e.g., brass or bronze alloys),
tungsten carbide, or another suitable material.
[0032] The continuous superhard bearing surface 104 of the
continuous superhard bearing element 102 may exhibit a relatively
smooth surface finish. In an embodiment, a bearing apparatus
includes a thrust-bearing assembly that includes continuous
superhard bearing element 102 and another bearing assembly (e.g., a
tilting pad bearing assembly). As the thrust-bearing assembly that
includes the continuous superhard bearing element 102 rotates
relative to the other bearing surface of the other bearing
assembly, a fluid film may develop between the continuous superhard
bearing surface 104 of the continuous superhard bearing element 102
and the surface of the other bearing assembly, thereby increasing
the wear resistance and/or performance of the bearing apparatus. A
smooth surface finish may facilitate the formation of the fluid
film between the bearing surfaces of the bearing apparatus. For
example, a surface defect caused by a rough surface finish (e.g., a
bump, a ridge, etc.) on the continuous superhard bearing surface
104 of the continuous superhard bearing element 102 may prevent the
development of a sufficient fluid film at least proximate the
defect. The surface defect may also increase the friction or
contact between the bearing surfaces. Such conditions may result in
chipping, power losses, cracking or increased wear on both bearing
surfaces. As such, the continuous superhard bearing surface 104 of
the continuous superhard bearing element 102 and/or the surface of
the other bearing assembly may include a smooth surface finish. In
an embodiment, the surface finish of the continuous superhard
bearing surface 104 of the continuous superhard bearing element 102
or any other surface of the bearing apparatus (e.g., the tilting
pad bearing assembly) may have a surface finish less than about
0.89 .mu.m (about 35 microinches) (e.g., less than about 0.64 .mu.m
(about 25 microinches), less than about 0.38 .mu.m (about 15
microinches), less than about 0.25 .mu.m (about 10 microinches),
less than about 0.13 .mu.m (about 5 microinches)) as measured, for
example, by a profilometer by root mean square (RMS). In another
embodiment, the surface finish of the continuous superhard bearing
surface 104 of the continuous superhard bearing element 102 or any
other surface of the bearing apparatus may have a surface finish of
about 0.64 .mu.m (25 microinches) to about 0.89 .mu.m (about 35
microinches), about 0.38 .mu.m (about 15 microinches) to about 0.64
.mu.m (about 25 microinches), about 0.38 .mu.m (about 15
microinches) to about 0.51 .mu.m (about 20 microinches), about 0.25
.mu.m (about 10 microinches) to about 0.38 .mu.m (about 15
microinches), about 0.18 .mu.m (about 7 microinches) to about 0.25
.mu.m (about 10 microinches), about 0.13 .mu.m (about 5
microinches) to about 0.18 .mu.m (about 7 microinches), about 0.064
.mu.m (about 2.5 microinches) to about 0.13 .mu.m (about 5
microinches), less than about 0.064 .mu.m (about 2.5 microinches),
less than about 0.051 .mu.m (about 2 microinches), less than about
0.025 .mu.m (about 1 microinch), or submicrometers
(submicroinches). The surface finish of any bearing surface of the
bearing apparatuses disclosed herein may exhibit any of the
disclosed surface finishes and may be selected based on the type of
fluid used for lubrication of the bearing surfaces, the expected
fluid pressure or flow through the bearing apparatus, the expected
rate of rotation, the expected load in the bearing apparatus and
the expected tilting of any tilting pad in a bearing assembly,
other performance criteria, or combinations thereof.
[0033] The continuous superhard bearing element 102 may have a
maximum lateral width "W," such as a maximum diameter. In an
embodiment, the maximum lateral width "W" of the continuous
superhard bearing element 102 is greater than about 5.1 cm (about 2
inches) (e.g., greater than about 7.6 cm (about 3 inches), greater
than about 12.7 cm (about 5 inches). In another embodiment, the
maximum lateral width "W" of the continuous superhard bearing
element 102 is about 5.1 cm (about 2 inches) to about 7.6 cm (about
3 inches), about 7.6 cm (about 3 inches) to about 12.7 cm (about 5
inches), about 12.7 cm (about 5 inches) to about 17.8 cm (about 7
inches), about 17.8 cm (about 7 inches) to about 25.4 cm (about 10
inches), about 25.4 cm (about 10 inches) to about 30.5 cm (about 12
inches) (e.g., 28 cm (about 11 inches)), or about 30.5 cm (about 12
inches) to about 40.6 cm (about 16 inches). In some applications,
the maximum lateral width "W" of the continuous superhard bearing
element 102 may be less than about 5.1 cm (about 2 inches). The
maximum lateral width "W" of the continuous superhard bearing
element 102 may be limited at least partially based on the type of
material used for the continuous superhard bearing element 102.
[0034] The continuous superhard bearing element 102 may be formed
from of a variety of superhard materials. The term "superhard"
means a material having a hardness at least equal to the hardness
of tungsten carbide, silicon carbide, or silicon nitride. In an
embodiment, the continuous superhard bearing element 102 may
include polycrystalline cubic boron nitride, polycrystalline
diamond (e.g., formed by chemical vapor deposition or by HPHT
sintering), diamond crystals, silicon carbide, silicon nitride,
tantalum carbide, tungsten carbide (e.g., binderless tungsten
carbide, cobalt-cemented tungsten carbide), other metal carbides,
other superhard carbides, or combinations thereof. In another
embodiment, the continuous superhard bearing element 102 may be
composed of sintered or reaction-bonded silicon carbide, or
sintered or reaction-bonded silicon nitride. The sintered or
reaction-bonded silicon carbide, or sintered or reaction-bonded
silicon nitride may have additional materials therein. For example,
the additional materials in a sintered or reaction-bonded ceramic
may include diamond, polycrystalline diamond, cubic boron nitride,
a material exhibiting a hardness greater than the reaction-bonded
ceramic or a material exhibiting a thermal conductivity greater
than the reaction-bonded ceramic. Adding materials to the sintered
or reaction-bonded continuous superhard bearing element may
increase the thermal conductivity and/or wear resistance of
continuous superhard bearing element 102. For example, adding
diamond particles to sintered or reaction-bonded silicon carbide,
or sintered or reaction-bonded silicon nitride may increase the
wear resistance of the continuous superhard bearing element 102 by
more than 500%. In an embodiment, the diamond particles may be
added to the sintered or reaction-bonded ceramic in an amount less
that about 80 weight % (e.g., about 50 weight % to about 80 weight
%, about 25 weight % to about 50 weight %, or less than about 25
weight %). Suitable reaction-bonded ceramics from which the
superhard bearing element 102 may be made are commercially
available from M Cubed Technologies, Inc. of Newark, Del. In an
embodiment, the continuous superhard bearing element 102 may be
formed from a single material or a single piece of any of the
superhard materials disclosed herein.
[0035] In the illustrated embodiment, the continuous superhard
bearing element 102 includes a superhard table 108 defining the
continuous superhard bearing surface 104 and a substrate 110 to
which the superhard table 108 is bonded. In an embodiment, the
continuous superhard bearing element 102 may be a polycrystalline
diamond compact ("PDC"). The PDC includes a polycrystalline diamond
("PCD") table defining the superhard table 108 to which the
substrate 110 is bonded. For example, the substrate 110 may
comprise a cobalt-cemented tungsten carbide substrate. The PCD
table includes a plurality of directly bonded-together diamond
grains exhibiting diamond-to-diamond bonding therebetween (e.g.,
sp.sup.3 bonding), which define a plurality of interstitial
regions. A portion of, or substantially all of, the interstitial
regions of such the PCD table may include a metal-solvent catalyst
or a metallic infiltrant disposed therein that is infiltrated from
the substrate 110 or from another source. For example, the
metal-solvent catalyst or metallic infiltrant may be selected from
iron, nickel, cobalt, and alloys of the foregoing. The PCD table
may further include thermally-stable diamond in which the
metal-solvent catalyst or metallic infiltrant has been partially or
substantially completely depleted from a selected surface or volume
of the PCD table 108, for example, an acid leaching process.
[0036] For example, appropriately configured PDCs may be used as
the continuous superhard bearing element 102, which may be formed
in an HPHT processes. Suitable PDCs having a PCD table with a
maximum diameter over 6.4 cm (about 2.5 inches) are commercially
available from Iljin Diamond Co., Ltd. of Korea. For example,
diamond particles may be disposed adjacent to the substrate 110,
and subjected to an HPHT process to sinter the diamond particles to
form the PCD table that bonds to the substrate 110, thereby forming
the PDC. The temperature of the HPHT process may be at least about
1000.degree. C. (e.g., about 1200.degree. C. to about 1600.degree.
C.) and the cell pressure of the HPHT process may be at least 4.0
GPa (e.g., about 5.0 GPa to about 12 GPa or about 7.5 GPa to about
11 GPa) for a time sufficient to sinter the diamond particles.
[0037] The diamond particles may exhibit an average particle size
of about 50 .mu.m or less, such as about 30 .mu.m or less, about 20
.mu.m or less, about 10 .mu.m to about 18 .mu.m, or about 15 .mu.m
to about 18 .mu.m. In some embodiments, the average particle size
of the diamond particles may be about 10 .mu.m or less, such as
about 2 .mu.m to about 5 .mu.m or submicron. In some embodiments,
the diamond particles may comprise a relatively larger size and at
least one relatively smaller size. As used herein, the phrases
"relatively larger" and "relatively smaller" refer to particle
sizes (by any suitable method) that differ by at least a factor of
two (e.g., 30 .mu.m and 15 .mu.m). According to various
embodiments, the mass of diamond particles may include a portion
exhibiting a relatively larger size (e.g., 30 .mu.m, 20 .mu.m, 15
.mu.m, 12 .mu.m, 10 .mu.m, 8 .mu.m) and another portion exhibiting
at least one relatively smaller size (e.g., 6 .mu.m, 5 .mu.m, 4
.mu.m, 3 .mu.m, 2 .mu.m, 1 .mu.m, 0.5 .mu.m, less than 0.5 .mu.m,
0.1 .mu.m, less than 0.1 .mu.m). In one embodiment, the diamond
particles may include a portion exhibiting a relatively larger size
between about 10 .mu.m and about 40 .mu.m and another portion
exhibiting a relatively smaller size between about 1 .mu.m and 4
.mu.m. In some embodiments, the diamond particles may comprise
three or more different sizes (e.g., one relatively larger size and
two or more relatively smaller sizes), without limitation. The PCD
table 108 so-formed after sintering may exhibit an average diamond
grain size that is the same or similar to any of the foregoing
diamond particle sizes and distributions.
[0038] More details about diamond particle sizes and diamond
particle size distributions that may be employed to form the PCD
table in any of the embodiments disclosed herein are disclosed in
U.S. patent application Ser. No. 13/734,354; U.S. Provisional
Patent Application No. 61/948,970; and U.S. Provisional Patent
Application No. 62/002,001. U.S. patent application Ser. No.
13/734,354; U.S. Provisional Patent Application No. 61/948,970; and
U.S. Provisional Patent Application No. 62/002,001 are each
incorporated herein, in their entirety, by this reference.
[0039] In an embodiment, the superhard table 108 may be integrally
formed with the substrate 110. For example, the superhard table 108
may be a sintered PCD table that is integrally formed with the
substrate 110. In such an embodiment, the infiltrated metal-solvent
catalyst from the substrate 110 may be used to catalyze formation
of diamond-to-diamond bonding between diamond grains of the
superhard table 108 from diamond powder during HPHT processing. In
another embodiment, the superhard table 108 may be a pre-formed
superhard table that has been HPHT bonded or brazed to the
substrate 110 in a second HPHT process after being initially formed
in a first HPHT process. For example, the superhard table 108 may
be a pre-formed PCD table that has been leached to substantially
completely remove metal-solvent catalyst used in the manufacture
thereof and subsequently HPHT bonded or brazed to the substrate 110
in a separate process.
[0040] In some embodiments, the superhard table 108 may be leached
to deplete a metal-solvent catalyst or a metallic infiltrant
therefrom in order to enhance the thermal stability of the
superhard table 108. For example, when the superhard table 108 is a
PCD table, the superhard table 108 may be leached to remove at
least a portion of the metal-solvent catalyst from a working region
thereof to a selected depth that was used to initially sinter the
diamond grains to form a leached thermally-stable region. The
leached thermally-stable region may extend inwardly from the
continuous superhard bearing surface 104 to a selected depth. In
one example, the depth of the thermally-stable region may be about
10 .mu.m to about 600 .mu.m. More specifically, in some
embodiments, the selected depth is about 50 .mu.m to about 100
.mu.m, about 200 .mu.m to about 350 .mu.m, or about 350 .mu.m to
about 600 .mu.m. The leaching may be performed in a suitable acid,
such as aqua regia, nitric acid, hydrofluoric acid, or mixtures of
the foregoing.
[0041] The substrate 110 may also be formed from any number of
different materials, and may be integrally formed with, or
otherwise bonded or connected to, the superhard table 108.
Materials suitable for the substrate 110 may include, without
limitation, cemented carbides, such as tungsten carbide, titanium
carbide, chromium carbide, niobium carbide, tantalum carbide,
vanadium carbide, or combinations thereof cemented with iron,
nickel, cobalt, or alloys thereof. For example, in an embodiment,
the substrate 110 comprises cobalt-cemented tungsten carbide.
However, in certain embodiments, the superhard tables 108 may be
omitted, and the continuous superhard bearing element 102 may be
made from a superhard material, such as cobalt-cemented tungsten
carbide. In other embodiments, the substrate 110 may be omitted and
the continuous superhard bearing element 102 may be a superhard
material, such as a polycrystalline diamond body that has been
leached to deplete metal-solvent catalyst therefrom or may be an
un-leached PCD body.
[0042] A hole 112 may be formed in the continuous superhard bearing
element 102 using a variety of techniques. The hole 112 may be
sized and configured to receive a rotating shaft of pump, turbine,
or other machine. In an embodiment, the hole 112 may be machined
into a disk from which the continuous superhard bearing element 102
is made using electrical discharge machining (e.g., plunge
electrical discharge machining and/or wire electrical discharge
machining), drilling, laser drilling, other suitable techniques, or
combinations thereof. For example, plunge electrical discharge
machining may be used to create a small starter though hole in the
disk from which the continuous superhard bearing element 102 is
made. Wire electrical discharge machining may then be used to
enlarge the small starter though hole to form the hole 112. In
another example, a laser is used to create the small starter
through hole or the laser may be used to form the hole 112. In
another embodiment, a sacrificial material that is more easily
removed than the superhard material from which the superhard
bearing element 102 is made may be used to define the hole 112 of
the continuous superhard bearing element 102. For example, a
sacrificial material (e.g., tungsten, tungsten carbide, hexagonal
boron nitride, or combinations thereof) is laterally surrounded by
unsintered diamond particles and is then subjected to an HPHT
process. The sacrificial material is then removed from the PCD
table so formed (e.g., mechanically, by blasting or via a leaching
process) from the PCD surrounding it to form the hole 112.
[0043] In another embodiment, the continuous superhard bearing
element 102 may include a coating that forms the continuous
superhard bearing surface 104. The coating may be formed using a
chemical vapor deposition technique, a physical vapor deposition
technique, or any other deposition technique. For example, diamond
may be deposited on a less hard surface to form the continuous
superhard bearing surface 104 using a chemical or physical vapor
deposition technique.
[0044] FIGS. 2A and 2B are isometric and isometric partial
cross-sectional views, respectively, of a tilting pad
thrust-bearing assembly 200 according to an embodiment. The tilting
pad thrust-bearing assembly 200 includes a support ring 218 that
carries a plurality of circumferentially spaced tilting pads 216.
The tilting pads 216 may include, for instance, fixed tilting pads,
adjustable tilting pads, self-establishing tilting pads, other
bearing pads or elements, or combinations of the foregoing.
Examples of tilting pad thrust-bearing assemblies for the tilting
pad thrust-bearing assembly 200 are disclosed in U.S. Pat. No.
8,545,103, the disclosure of which is incorporated herein, in its
entirety, by this reference.
[0045] The bearing surface of each of the tilting pads 216 of the
illustrated embodiment generally has a truncated pie-shaped
geometry or a generally trapezoidal geometry, and may be
distributed about a thrust axis 220, along which a thrust force may
be generally directed during use. Each tilting pad 216 may be
located circumferentially adjacent to another tilting pad 216, with
a circumferential space 222 or other offset therebetween. For
instance, the circumferential space 222 may separate adjacent
tilting pads 216 by a distance of about 2.0 mm to about 20.0 mm, or
a distance of about 3.5 mm to about 15 mm, although the separation
distance may be greater or smaller. For instance, as the size of
the tilting pad bearing assembly 200 increases, the size of the
tilting pads 216 and/or the size of the circumferential space 222
may also increase. For example, the tilting pads 216 may exhibit a
nominal radial width less than about 7.6 cm (about 3 inches) (e.g.,
less than about 5.1 cm (about 2 inches), less than about 2.5 cm
(about 1 inch), less than 1.3 cm (about 0.5 inches), between 0.64
cm (about 0.25 inches) to about 1.3 cm (about 0.5 inches), between
about 1.3 cm (about 0.5 inches) to about 2.5 cm (about 1 inch),
between about 2.5 cm (about 1 inch) to about 5.1 cm (about 2
inches)). In other embodiment, the tilting pads 216 may exhibit a
nominal radial width greater than about 7.6 cm (about 3
inches).
[0046] Each tilting pad 216 may include a discrete superhard
bearing element 224, such that the tilting pads 216 collectively
provide a non-continuous superhard bearing surface. The superhard
bearing element 224 may include a superhard table 226 that may be
bonded to a substrate 228. For example, the superhard bearing
element 224 may be formed from any of the materials and compacts
previously described with respect to the continuous superhard
bearing element 102.
[0047] To support the tilting pads 216 of the tilting pad
thrust-bearing assembly 200, the support ring 218 may define a
channel 230 and the tilting pads 216 may be placed within the
channel 230. In other embodiments, the support ring 218 may define
multiple pockets or otherwise define locations for the tilting pads
216. The tilting pads 216 may then be supported or secured within
the support ring 218 in any suitable manner. For instance, as
discussed hereafter, a pivotal connection may be used to secure the
tilting pads 216 within the support ring 218, although any other
suitable securement or attachment mechanism may also be utilized.
The support ring 218 may also include an inner, peripheral surface
defining a hole 212. The hole 212 may be generally centered about
the thrust axis 220, and may be adapted to receive a shaft (e.g., a
downhole drilling motor shaft). The support ring 218 may be formed
of the same materials as the support ring 106.
[0048] In the illustrated embodiment, the tilting pad
thrust-bearing assembly 200 includes 10 tilt pads. In other
embodiments, more or less than 10 tilt pads may be used in the
tilting pad thrust-bearing assembly 200. For example, between 3 to
16 tilt pads (e.g., 3 to 6, 6 to 8, 8 to 10, or 10 to 12) may be
included in the tilting pad thrust-bearing assembly 200. The number
of tilt pads included in the tilting pad thrust-bearing assembly
200 may be chosen based on the expected load, the superhard
materials of the continuous superhard bearing element 102 and the
superhard bearing element 224, the size of the continuous superhard
bearing element 102, and the desired life of the bearing
apparatus.
[0049] In the embodiment illustrated in FIGS. 2A and 2B, the
tilting pads 216 may be used in connection with a runner or other
superhard bearing element (e.g., the continuous superhard bearing
element 102 shown in FIG. 1A). In general, the tilting pad bearing
assembly 200 may rotate relative to a runner or other bearing
assembly, while a lubricant or other fluid (e.g., seawater) floods
the tilting pad bearing assembly 200 and the runner/other bearing
assembly. For example, as the runner 100 is rotated relative to a
tilt pad bearing assembly 200, a fluid film separating the
runner/other bearing assembly from a superhard bearing element 224
may develop. For favorable use of the hydrodynamic forces within
the lubricant, the tilting pads 216 may tilt which may result in a
higher lubricant film thickness existing at a leading edge (i.e.,
an edge of a tilting pad 216 that would be traversed first by a
reference line on the runner while the runner 100 moves in the
direction of rotation), than at a trailing edge (i.e., an edge of a
tilting pad 216 over which such reference line is second to pass in
the direction of rotation), at which or near which a minimum film
thickness may develop. The tilt pads may be manufactured such that
respective superhard bearing surfaces thereof exhibit the same or
similar smooth surface finishes as the continuous superhard bearing
element 102, as previously described. Of course, in other
embodiments, the tilt pad bearing assembly 200 may rotate with
respect to the runner 100, if desired, without limitation.
[0050] In the illustrated embodiment, each of the plurality of
superhard bearing elements 224 is secured to a support plate 232
(FIG. 2B). The support plate 232 may, for example, be formed of a
metal, an alloy, a cemented carbide material, other material, or
any combination thereof. The substrate 228 of the superhard bearing
element 224 may be secured to the support plate 232 by brazing,
welding, or other method. In some embodiments, the support plate
232 may define a pocket into which the superhard bearing segments
may be tiltably or fixedly assembled and/or positioned. In an
embodiment, the support plate 232 has an integral construction such
that a single body may form substantially the full support plate
232. In other embodiments, multiple segments of one or more
materials may be used to form or define the support plate 232. In
another embodiment, multiple superhard bearing segments may be used
to form the superhard bearing element 224.
[0051] The degree to which the tilting pads 216 rotate or tilt may
be varied in any suitable manner. For instance, in an embodiment,
the tilting pads 216 may be tilted about respective radial axes
that extend generally radially from the thrust axis 220. In FIG.
2B, the support plate 232 may be attached to a pin 234. The pin 234
may, for example, be formed of a metal, an alloy, a cemented
carbide material, other material, or any combinations thereof. The
pin 234 may be allowed to at least partially rotate, or may
otherwise define or correspond to a tilt axis 236. For example,
according to some embodiments, the pin 234 is journaled or
otherwise secured within the support ring 218 in a manner that
allows the pin 234 to rotate relative to the support ring 218. The
pin 234 may be fixed to the support plate 232 such that as the pin
234 rotates relative to the support ring 218, the support plate 232
may also rotate or tilt relative to the tilt axis 236 of the pin
234. The pin 234 and support plate 232 may rotate or tilt between
zero and twenty degrees in some embodiments, such that the
superhard bearing element 224 of the respective tilting pads 216
may also tilt between about zero and about twenty degrees relative
to the pin 234 or other horizontal axis. In other embodiments, the
pin 234 and/or the superhard bearing element 224 may rotate between
about zero and about fifteen degrees, such as a positive or
negative angle (.theta.) of about 0.5 to about 3 degrees (e.g.,
about 0.5 to about 1 degree or less than 1 degree) relative to the
tilt axis 236 of the pin 234. In some cases, the support ring 218
may be configured for bidirectional rotation. In such a case, the
pin 234 may be allowed to rotate in clockwise and/or
counter-clockwise directions. For example, the superhard bearing
element 224 may thus tilt in either direction relative to the axis
of the pin 234 and/or the support ring 218. For instance, the
superhard bearing element 224 may be rotated to a position anywhere
between a positive or negative angle of about twenty degrees
relative to an axis of the pin 234, such as a positive or negative
angle (.theta.) of about 0.5 to about 3 degrees (e.g., about 0.5 to
about 1 degree or less than 1 degree) relative to the tilt axis 236
of the pin 234.
[0052] The pin 234 may be used to allow one or more tilting pads
216 to selectively rotate. For instance, the tilting pads 216 may
be self-establishing or limiting such that the tilting pads 216 may
automatically or otherwise adjust to a desired tilt or other
orientation based on the lubricant used, the axial forces applied
along the thrust axis, the rotational speed of the runner and/or
the tilting pad bearing assembly 200, other factors, or
combinations of the foregoing. In still other embodiments, the
tilting pads 216 may be fixed at a particular tilt, or may be
manually set to a particular tilt with or without being
self-establishing.
[0053] Further, the pin 234 represents a single mechanism for
facilitating rotation, translation, or other positioning of the
tilting pads 216 so as to provide tilting pad superhard bearing
element 224. In other embodiments, other mechanisms may be used. By
way of illustration, leveling links, pivotal rockers, spherical
pivots, other elements, or any combination of the foregoing may
also be used to facilitate positioning of the tilting pads 216 in a
tilted configuration. In an embodiment, the support plate 232 may
be used to facilitate rotation of a respective tilting pad 216. The
support plate 232 may, for instance, be machined or otherwise
formed to include a receptacle, an opening, or other structure into
which the pin 234 may be at least partially received or secured. In
embodiments in which the pin 234 is excluded, the support plate 232
may be machined or otherwise formed to include other components,
such as spherical pivot, pivotal rocker, or leveling link
interface. The support plate 232 may be formed of any suitable
material, such as steel or other alloy; however, in some
embodiments the support plate 232 is formed of a material that is
relatively softer than the substrate 228, such that the support
plate 232 may be relatively easily machined or formed into a
desired shape or form. In other embodiments, the support plate 232
can be eliminated and the substrate 228 may be directly machined or
formed to facilitate tilting of the tilting pad 216. Examples of
tilting mechanisms that may be used for tilting the tilting pads
disclosed herein are disclosed in U.S. Patent Published Application
No. 20140102810, the disclosure of which is incorporated herein, in
its entirety, by this reference.
[0054] In some embodiments, the tilt axis of the tilting pads 216
may be aligned with a radial reference line dividing (e.g.,
symmetrically) the bearing surface 223. For example, where the
support ring 218 may be configured for bi-directional rotation, the
tilt axis of the tilting pads 216 may be centered circumferentially
between opposing edges of the tilting pads 216 (e.g., the leading
edge and the trailing edge). In other embodiments, the tilt axis of
a tilting pad 216 may be offset relative to a center of the bearing
surface 223 of the tilting pad 216. For example, where the support
ring 218 is part of a rotor configured for only unidirectional
rotation, the axis of rotation of the tilting pad 216 may be offset
such that the axis of rotation is closer to one of the leading edge
or the trailing edge of the tilting pad 216. In other embodiments,
a tilt axis may be offset from a circumferential center of its
bearing surface despite a rotor being configured for bidirectional
rotation, or a tilt axis may be circumferentially centered despite
a rotor being configured for unidirectional rotation.
[0055] FIGS. 2C and 2D are isometric and cross-sectional views,
respectively, of a single one of the tilting pads 216 shown in
FIGS. 2A and 2B that may be used in connection with the tilting pad
bearing assembly 200 described above. The tilting pad 216 includes
the continuous superhard bearing element 224. As previously
discussed, each tilting pad 216 may include the superhard table 226
bonded to the substrate 228, and the substrate 228 may further be
secured within the support plate 232 by brazing, using high
temperature adhesives, press-fitting, fastening with fasteners, or
other suitable attachment mechanism. In the illustrated embodiment,
the support plate 232 may facilitate attachment of the substrate
228 to the support plate 232 by including an interior surface 238
that defines an interior pocket 240. The interior pocket 240 may be
sized to generally correspond to a size of the substrate 228. It is
noted that the support plate 232 merely represents one embodiment
for a support plate and other configurations may be used. For
example, according to another embodiment, a support plate may lack
a pocket or other receptacle. In still another embodiment, the
support plate may be eliminated.
[0056] In the illustrated embodiment, a superhard bearing surface
223 of the superhard bearing element 224 (e.g., the superhard table
226) is substantially planar, although such an embodiment is merely
illustrative. In other embodiments, the superhard bearing surface
223 of the superhard bearing element 224 may be curved, or have
another contour or topography. Moreover, outer edges of the
superhard bearing element 224 may optionally include a chamfer 242.
The chamfer 242 may be formed by placing a chamfer on the
individual outer edge regions of the superhard bearing element 224
or, if present, the superhard table 226. The superhard bearing
element 224 may also take a number of other forms. For example, in
FIG. 2C, the superhard bearing surface 223 is substantially
pie-shaped with a chamfered edge. In other embodiments, the edges
of a superhard bearing element 224 may define other shapes,
including radiused, arcuate, generally circular, generally
elliptical, generally trapezoidal, other shaped surfaces, or may
form a sharp edge, or combinations thereof.
[0057] FIGS. 3 and 4 illustrate top plan and isometric views,
respectively, of different embodiments of tilting pads that may be
employed in a tilting pad bearing assembly according to an
embodiment. FIG. 3 illustrates a tilting pad 316 that may include a
plurality of superhard bearing segments 344a-d, each of which
includes a superhard bearing element 324 that may include a
superhard table 326 bonded to a substrate (not shown). The
superhard table 326 and substrate (not shown) is optionally bonded
or otherwise connected to a support plate 332. Each superhard table
326 includes a superhard bearing surface 327 that collectively form
a larger, substantially continuous superhard bearing surface.
[0058] The superhard bearing segments 344a-d each may include an
outer edge region 346 and an interior edge region 348. The
superhard bearing segments 344a-d may be configured with a serrated
geometry at the interior edge regions 348. Such a configuration may
allow adjacent superhard bearing segments 344a-d to mate and at
least partially interlock, while also defining seams 350 of a
geometry that limits fluid leakage radially through the gaps
between adjoining superhard bearing segments 344a-d.
[0059] The illustrated and described seams 350 between adjacent
superhard bearing segments 344 are merely illustrative, and seams
350 between superhard bearing segments 344 and/or configurations of
interior edge regions 348 of superhard bearing segments 344 may
have any number of configurations. For, instance, a set of
interconnecting superhard bearing segments may have substantially
straight, serrated, saw-toothed, sinusoidal-like, curved, or
otherwise shaped interior edge regions, or any combination of the
foregoing. Moreover, some portions of an interior edge region may
have one configuration of shape while another portion of an
interior edge region on the same superhard bearing segment may have
a different configuration or shape. Accordingly, different
superhard bearing segments may also include different mating
geometry or other configurations. The plurality of superhard
bearing segments 344a-d may have a coating thereon that at least
partially fills the seams 350. The coating may be applied using
chemical vapor deposition, physical vapor deposition, other
deposition techniques or combinations thereof. Additionally,
sealant materials may at least partially fill the seams 350, such
as braze alloy, tungsten carbide, polycrystalline diamond, other
ceramic materials, or combinations thereof.
[0060] As discussed herein, a tilting pad bearing assembly
including superhard bearing segments may be utilized where certain
conditions are met, or in any number of other circumstances or
industries. For instance, an application may be identified where it
would benefit to use a superhard bearing element including a
superhard material. However, the superhard material may have
associated production limits (e.g., size, availability, etc.).
Where the superhard bearing element has a size, shape, or other
feature(s) exceeding such production limits, the superhard bearing
element may be fashioned out of multiple individual segments that
collectively define a superhard bearing surface of the superhard
bearing element. In other cases, however, the type of material used
in the superhard bearing element may not have the same production
limits as PDCs or other superhard materials, or the superhard
bearing element may be sized small enough to allow a single
superhard or other material to be used to form the superhard
bearing surface.
[0061] FIG. 4 illustrates an embodiment in which a tilting pad 416
may have a size and/or comprise a material configured such that a
single segment may form a substantially continuous surface of the
superhard bearing element 424. In particular, the tilting pad 416
may include a superhard table 426 bonded to a substrate 428. The
substrate 428 may in turn be bonded to a support plate 432.
Optionally, the support plate 432 is oversized relative to the
substrate 428; however, the support plate 432 may also be about the
same size or smaller than the substrate 428. In this embodiment, a
single element may define substantially the entire superhard
bearing element 424. For instance, the element may exhibit a length
and/or width that may measure approximately 15 mm by 10 mm, such
that a single superhard table 426 made from polycrystalline diamond
or other materials may be fashioned into the desired shape, even in
the absence of providing multiple interlocking, adjoining, or
adjacent segments. In other embodiments, the element may have other
sizes and may even exceed a maximum size available for PDCs. For
instance, other superhard materials (e.g., tungsten carbide,
reaction-bonded ceramics, reaction-bonded ceramics containing
diamond particles) or any other superhard material disclosed herein
may be used to form the superhard bearing element 424 using a
single, integral segment.
[0062] Any of the above-described embodiments including a bearing
assembly having a continuous superhard bearing element and/or a
tilting pad bearing assembly may be employed in a thrust-bearing
apparatus. For example, a thrust-bearing apparatus may include a
rotor configured as the thrust-bearing assembly 100 and a stator
configured as the tilting pad thrust-bearing assembly 200, although
any combination of the bearing assemblies with the continuous
superhard bearing element and a tilting pad bearing assembly may be
employed in other embodiments. FIGS. 5A is an isometric cutaway
view of a thrust-bearing apparatus 500 according to an embodiment.
FIG. 5B is a partial cross-sectional schematic representation of a
thrust-bearing apparatus 500 during use. One of the bearing
assemblies is a stator while the other bearing assembly is a rotor.
In the illustrated embodiment, the tilting pad bearing assembly is
a stator 552 and the bearing assembly having the continuous
superhard bearing element is a rotor 554. The stator 552 and rotor
554 may be configured as any of the described embodiments of
bearing assemblies. The terms "rotor" and "stator" refer to
rotating and stationary components of the tilting pad bearing
apparatus 500, respectively, although the rotating and stationary
status of the illustrated embodiments may also be reversed.
[0063] The stator 552 may include a support ring 506 and a
plurality of tilting pads 516 mounted or otherwise attached to a
support ring 518, with each of the tilting pads 516 having a
superhard bearing element. The tilting pads 516 may be tilted
and/or tilt relative to a rotational axis 520 of the thrust-bearing
apparatus 500 and/or one or more surfaces of the support ring 506.
The tilting pads 516 may be fixed at a particular tilt, may be
manually adjusted to exhibit a particular tilt, may self-establish
at a particular tilt, or may be otherwise configured.
[0064] The rotor 554 may be configured in any suitable manner,
including in accordance with any of the embodiments described
herein. The rotor 554 may include a support ring 506 connected to
continuous superhard bearing element 502. The continuous superhard
bearing element 502 of the rotor 554 is generally adjacent to the
superhard bearing elements of the stator 552. A fluid film may
develop between the continuous superhard bearing element 502 of the
rotor 554 and the superhard bearing element of the stator 552. The
continuous superhard bearing element 502 may be mounted or
otherwise attached to a support ring 518 by brazing, a press-fit,
mechanical fasteners, or in another manner.
[0065] As shown in FIG. 5A, a shaft 556 may be coupled to the
support ring 506 and operably coupled to an apparatus capable of
rotating the shaft section 556 in a direction R (or in an opposite
direction). For example, the shaft 556 may extend through and may
be secured to the support ring 506 of the rotor 554 by
press-fitting or a threaded connection that couples the shaft 556
to the support ring 506, or by using another suitable technique. A
housing 558 may be secured to the support ring 518 of the stator
552 by, for example, press-fitting or threadly coupling the housing
558 to the support ring 518, and may extend circumferentially about
the shaft 556, the stator 552, and the rotor 554.
[0066] The operation of the thrust-bearing apparatus 500 is
discussed in more detail with reference to FIG. 5B. FIG. 5B is a
partial cross-sectional schematic representation in which the shaft
556 and housing 558 are not shown for clarity. In operation,
lubrication, drilling fluid, mud, or some other fluid may be pumped
between the shaft 556 and the housing 558, and between the tilting
pads 516 of the stator 552 and the continuous superhard bearing
element 502 of the rotor 554. More particularly, rotation of the
rotor 554 at a sufficient rotational speed may sweep the fluid onto
superhard bearing elements of the stator 552 and may allow a fluid
film 560 to develop between the continuous superhard bearing
element 502 of the rotor 554 and the superhard bearing element of
the stator 552. The fluid film 560 may develop under certain
operational conditions in which the rotational speed of the rotor
554 is sufficiently great and the thrust load is sufficiently
low.
[0067] In an embodiment, the tilting pads 516 may be positioned at
a fixed tilt angle or at a configurable or self-establishing tilt
angle. The tilting pads 516 of the stator 552 may have a leading
edge 562 at a different position than a trailing edge 564 relative
to the rotor 554. For instance, in FIG. 5B, the tilting pads 516
may be tilted such that a greater separation exists between the
tilting pads 516 and the continuous superhard bearing element 502
at a leading edge 562 (illustrated on one tilting pad 516) than at
a trailing edge 564 (illustrated on another tilting pad 516, for
clarity). Under such circumstances, the lubricant film 560 may have
a variable thickness across the tilting pad 516. In this particular
embodiment, a higher lubricant film thickness may exist at the
leading edge 562 than at the trailing edge 564.
[0068] Under certain operational conditions, the pressure of the
fluid film 560 may be sufficient to substantially prevent contact
between the continuous superhard bearing element 502 of the rotor
554 and the superhard bearing elements of the stator 552 and thus,
may substantially reduce wear of the continuous superhard bearing
element 502 and the superhard bearing elements. When the thrust
loads exceed a certain value and/or the rotational speed of the
rotor 554 is reduced, the pressure of the fluid film 560 may not be
sufficient to substantially prevent the continuous superhard
bearing element 502 of the rotor 554 and the superhard bearing
elements of the stator 552 from contacting each other. Under such
operational conditions, the thrust-bearing apparatus 500 is not
operated as a hydrodynamic bearing. Thus, under certain operational
conditions, the thrust-bearing apparatus 500 may be operated as a
hydrodynamic bearing apparatus and under other conditions the
thrust-bearing apparatus 500 may be operated so that the continuous
superhard bearing element 502 and superhard bearing elements of the
tilting pad 516 contact each other during use or a partially
developed fluid film is present between the continuous superhard
bearing element 502 and superhard bearing elements of the tilting
pad 516. However, the superhard bearing elements of the plurality
of tilting pads 516 and continuous superhard bearing element 502
may comprise superhard materials that are sufficiently
wear-resistant to accommodate repetitive contact with each other,
such as during start-up and shut-down of a system employing the
thrust-bearing apparatus 500 or during other operational conditions
not favorable for forming the fluid film 560. In still other
embodiments, a backup roller or other bearing (not shown) may also
be included for use during certain operational conditions, such as
during start-up, or as the fluid film 560 develops.
[0069] In an embodiment, the continuous superhard bearing element
502 and one or more of the plurality of tilt pads 516 may be formed
from different materials. For example, the continuous superhard
bearing element 502 may be formed from any of the reaction-bonded
ceramics disclosed herein (e.g., reaction-bonded silicon carbide or
reaction-bonded silicon nitride with or without diamond) and the
bearing elements of each tilt pads 516 may be formed from a PDC or
any other type of polycrystalline diamond element disclosed herein.
Because the superhard bearing surface of the continuous superhard
bearing element 502 and one or more tilt pads 516 may include
different materials, a non-diamond bearing surface may wear
preferentially relative to wear of a polycrystalline diamond
bearing surface. Providing such a bearing assembly including
different material bearing surfaces may provide for better heat
transfer and better maintenance of the fluid film 560 between the
superhard bearing surfaces of the continuous superhard bearing
element 502 and the superhard bearing elements of the tilting pad
516 than if all the superhard bearing surfaces included the same
non-diamond superhard material (e.g., where both include silicon
carbide).
[0070] Polycrystalline diamond and reaction-bonded ceramics
containing diamond particles have substantially higher thermal
conductivity than superhard carbides, such as sintered silicon
carbide, reaction-bonded silicon carbide, or tungsten carbide.
Because one of the superhard bearing surfaces of the continuous
superhard bearing element 502 or the superhard bearing element of
the tilting pad 516 includes polycrystalline diamond or
reaction-bonded ceramics containing diamond particles, heat
generated during use (e.g., at non-diamond bearing surfaces) may be
better dissipated as a result of its proximity or contact with
polycrystalline diamond bearing surfaces. Thus, a bearing assembly
including a polycrystalline diamond or reaction-bonded ceramics
containing diamond particles bearing surfaces may provide increased
wear resistance as compared to a bearing assembly in which all the
bearing surfaces include a non-diamond superhard materials (e.g.,
silicon carbide), but at significantly lower cost than would be
associated with a bearing assembly in which both of the opposed
bearing surfaces include only polycrystalline diamond.
[0071] In an embodiment, at least one superhard bearing element of
the stator 552 may include at least one non-diamond superhard
bearing surface, such as only including non-diamond bearing
surfaces. Meanwhile the rotor 554 may include a polycrystalline
diamond continuous superhard bearing element 502. The stator 552
within the tilting pad bearing apparatus 500 often fails before the
rotor 554. In some instances, this may occur because the stator 552
bearing surfaces are often subjected to unequal heating and wear.
For example, wear on the stator 552 is often unequal as a result of
a small number of stator 552 bearing elements beings somewhat more
"prominent" than the other stator 552 bearing elements. As a
result, contact, heating, and wear during use may be preferentially
associated with these more prominent stator 552 bearing elements.
For example, the bulk of the load and resulting wear may be borne
by, for example, the one to three most prominent bearing elements,
while the other stator 552 bearing elements may show little wear by
comparison. Such wear may result from the difficulty of perfectly
aligning the bearing elements of the bearing assembly.
[0072] Because the stator 552 may typically wear faster than the
rotor, in an embodiment the stator 552 bearing elements may not
include diamond, but include a non-diamond superhard material, as
the stator 552 may fail first. In such an embodiment, the stator
552 may be replaced once failure or a given degree of wear occurs.
In another embodiment, the stator 552 may include at least one, one
or more, or only diamond bearing surfaces, and the rotor 554 may
not include a diamond bearing surface. It is currently believed
that having at least one diamond surface and at least one
non-diamond surface facilitates faster breaking in of the bearing
surfaces as the less hard bearing surfaces wear/break in relatively
faster. In other embodiments, both the continuous superhard bearing
element 502 and the superhard bearing elements of each tilt pads
516 may be formed from a PDC, diamond or any other type of
polycrystalline diamond element disclosed herein. In another
embodiment, both the continuous superhard bearing element 502 and
the superhard bearing elements of each tilt pads 516 may be formed
from non-polycrystalline diamond materials such as reaction-bonded
ceramics or other superhard materials. In yet another embodiment,
the continuous superhard bearing element 502 may be formed from
non-polycrystalline diamond materials such as reaction-bonded
ceramics or other superhard materials, and the superhard bearing
elements of each tilt pads 516 may be PDCs or other type of
polycrystalline diamond elements.
[0073] The concepts used in the thrust-bearing assemblies and
apparatuses described herein may also be employed in radial bearing
assemblies and apparatuses. FIGS. 6A to 6C are isometric, exploded,
and isometric partial cross-sectional views, respectively, of a
radial bearing apparatus 600 according to yet another embodiment.
The radial bearing apparatus 600 may include an inner race 654
(e.g., a runner or rotor) that may have an interior surface 668
defining an hole 612 for receiving a shaft or other component. The
inner race 654 may also include a continuous superhard bearing
element 602 positioned at or near an exterior surface 670 of the
inner race 654. The continuous superhard bearing element 602 may
include a convexly-curved continuous superhard bearing surface 604
and may be formed from any of the materials previously discussed
for use with the continuous superhard bearing element 102.
[0074] The support ring 606 of the inner race 654 may include a
circumferentially-extending recess that receive the continuous
superhard bearing element 602. The continuous superhard bearing
element 602 may be secured within the recess or otherwise secured
to the support ring 606 by brazing, press-fitting, using fasteners,
or another suitable technique. The support ring 606 may also define
an interior surface 668 defining an opening 612 that is capable of
receiving, for example, a shaft (not shown) or other apparatus.
[0075] The radial bearing apparatus 600 may further include an
outer race 652 (e.g., a stator) configured to extend about and/or
receive the inner race 654. The outer race 652 may include a
plurality of circumferentially-spaced tilting pads 616, each of
which may include a superhard bearing element 624. A superhard
bearing surface of the superhard bearing element 624 may be
substantially planar, although in other embodiments the surface of
the superhard bearing element 616 may be a concavely-curved
superhard bearing surface to generally correspond to shapes of
convexly-curved continuous superhard bearing surface 604 of the
inner race 654. The terms "rotor" and "stator" refer to rotating
and stationary components of the radial bearing system 600,
respectively. Thus, if the inner race is configured to remain
stationary, the inner race may be referred to as the stator and the
outer race may be referred to as the rotor.
[0076] Rotation of a shaft (not shown) secured to the inner race
654 may effect rotation of the inner race 654 relative to the outer
race 652. Drilling fluid or other fluid or lubricant may be pumped
between the continuous superhard bearing surface 604 of the
continuous superhard bearing element 602 of the inner race 654 and
the surface of the superhard bearing element 624 of the outer race
652. When the inner race 654 rotates, the leading edge sections of
the tilting pads 616 may sweep lubricant (e.g., drilling fluid or
other lubricant) onto the surface of the superhard bearing element
624 of the outer race 652. As previously described with respect to
the hydrodynamic tilting pad bearing apparatus 500, at sufficient
rotational speeds for the inner race 654, a fluid film may develop
between the superhard bearing element 624 of the tilting pads 618
and the continuous superhard bearing element 602, and may develop
sufficient pressure to maintain the superhard bearing element 624
and the continuous superhard bearing element 602 apart from each
other. Accordingly, wear on the superhard bearing element 624 and
continuous superhard bearing element 602 may be reduced compared to
when direct contact between superhard bearing element 624 and
continuous superhard bearing element 602 occurs.
[0077] As further illustrated in FIGS. 6A and 6B, the outer race
652 includes a support ring 618 extending about an axis 620. The
support ring 618 may include an interior channel 630 configured to
receive a set of tilting pad 616 superhard bearing elements 624
distributed circumferentially about the axis 620. Each tilting pad
616 may include a superhard table 626. The superhard bearing
element 624 may be curved (e.g., concavely-curved) or substantially
planar and, in some embodiments, may include a peripheral chamfer.
The tiling pad 616 may be formed from any of the superhard
materials and structures disclosed herein. In other embodiments,
the superhard bearing element 624 may be otherwise curved, lack a
chamfered edge, may have another contour or configuration, or any
combination of the foregoing. Each superhard table 626 may be
bonded to a corresponding substrate 628. Further, each superhard
bearing element 624 may be tilted circumferentially relative to an
imaginary cylindrical surface. The superhard tables 626 and
substrates 628 may be fabricated from the same materials described
above for the tilting pads 216 shown in FIGS. 2A and 2B.
[0078] Each superhard bearing element 624 of a corresponding
tilting pad 616 may be tilted in a manner that facilities sweeping
in of a lubricant or other fluid to form a fluid film between the
inner race 654 and the outer race 652. Each tilting pad 616 may be
tilted and/or tilt about an axis that is generally parallel to the
central axis 620. As a result, each tilting pad 616 may be tilted
at an angle relative to the inner and outer surfaces of the ring
618 and in a circumferential fashion such that the leading edges of
the tilting pads 616 are about parallel to the central axis 620.
The leading edge may help to sweep lubricant or another fluid onto
the surfaces of the superhard bearing elements 624 of the stator
652 to form a fluid film in a manner similar to the tilting pads
516 shown in FIGS. 5A and 5B. More particularly, when the inner
race 654 is concentrically positioned relative to the outer race
652, the leading edges may be offset relative to the outer edge of
the outer race 652, and by a distance that is larger than a
distance between the outer race 652 and a trailing edge of the
superhard bearing surface 624. It should be noted that in other
embodiments, the radial bearing apparatus 600 may be configured as
a journal bearing. In such an embodiment, the inner race 654 may be
positioned eccentrically relative to the outer race 652.
[0079] In some embodiments, the tilting pad 616 may be formed from
a plurality of superhard bearing segments (not shown) that
collectively define a respective tilting pad 616. Each superhard
bearing segment may be substantially identical, or the superhard
bearing segments may be different relative to other of the
superhard bearing segments. In some embodiments, the superhard
bearing segments each include a superhard table 626 bonded to a
substrate 628 as described herein. Optionally, the substrate 628
may be connected or supported relative to a support plate 632, the
support ring 618, or other material or component. Additionally,
seams (not shown) may be formed between circumferentially and/or
longitudinally adjacent to the superhard bearing elements 604. The
edges of the superhard bearing segments 626 may have any number of
configurations or shapes, and may correspond to or interlock with
adjoining edges in any number of different manners. Further,
sealant materials may be disposed within a gap (not shown) that may
be formed between adjacent superhard bearing segments to help
further prevent fluid leakage through the seams.
[0080] FIG. 7 is a partial isometric cutaway view of an embodiment
of a turbine system 700, such as a wind turbine system, which may
incorporate any of the bearing apparatus embodiments disclosed
herein. The turbine system 700 may include a housing 758 and a main
gear shaft 756 operably connected to another device such as a wind
turbine, i.e., blades attached to a hub, (not shown). At least one
rotor 754 including a continuous superhard bearing element 702 may
be operably connected to the main shaft 756. For example, the rotor
754 may be configured as the bearing assembly 100 shown in FIG. 1
or any other bearing assembly including a continuous superhard
bearing element disclosed herein. At least one stator 752 including
a plurality of tilting pads may be connected to the housing 758.
For example, the stator 752 may be configured as the bearing
assembly 200 shown in FIG. 2A or any other tilting pad bearing
assembly disclosed herein. The stator 752 or the rotor 754 may be a
split bearing (e.g., manufactured in multiple components) to
facilitate assembly. The shaft 756 may extend through a central
hole 712 in the rotor 754 and stator 752 and may be secured to each
rotor 754 by press fitting or otherwise attaching the gear shaft
756 to each rotor 754 bearing assembly, threadly coupling the shaft
756 to each rotor 754 bearing assembly, or another suitable
technique. In the illustrated embodiment, the wind turbine system
includes two bearing apparatuses. However, in other embodiments,
the wind turbine system may include one or more bearing apparatuses
(e.g., one bearing apparatus, or three or more bearing
apparatuses).
[0081] In an embodiment, the rotor 754 may include a support ring
706 and a continuous superhard bearing element 702 attached or
bonded to the support ring 706. The continuous superhard bearing
element 702 includes a continuous superhard bearing surface 704.
The continuous superhard bearing element 702 may include a
superhard table 708 bonded to a substrate 710. Similarly, the
stator 752 may include a support ring 718 having a channel 730
therein and a plurality of tilt pads 716 positioned inside the
channel 730. The plurality of tilting pads 716 may include a
superhard bearing element 724 that may have a superhard bearing
table 726 bonded to a substrate 728. The plurality of tilting pads
716 may further include a support plate 732 above a pin 734 wherein
the superhard bearing element 724 is bonded or attached to the
support place 732. While the stator 752 bearing assembly and the
rotor bearing assembly 754 is shown including only one row of the
superhard bearing elements 724 and 702, respectively, the stator
752 bearing assembly and the rotor bearing assembly 754 may include
two rows, three rows, or any number of suitable rows of the
superhard bearing elements.
[0082] In an embodiment, wind may turn the blades on the wind
turbine (not shown), which in turn may rotate the main shaft 756
about a rotation axis 720. The main shaft 756 may rotate the rotor
754 bearing assembly about the rotation axis 720. As shown, the
main shaft 756 may go through a gear transmission box 766. For
example, the main shaft 774 may be connected to a first gear 776
that turns a second gear 778 or vice versa. The first gear 776 may
be larger than the second gear 778. The second smaller gear 778 may
be connected to a shaft 780 that turns a generator (not shown) to
produce electricity.
[0083] As wind speed increases and energy builds within the system
700, the high thermal conductivity of a diamond or other high
thermal conductivity bearing element may help remove heat from the
contact surface between the surfaces of the bearing assemblies.
Such a configuration may help reduce the likelihood of temperature
induced strength reductions and/or failure in the bearing
assemblies. Further, in an embodiment where either the continuous
superhard bearing element 702 and at least one of the superhard
bearing elements 724 of the tilt pads 716 are formed of more than
one material, the modulus contrast between materials may help
provide resistance to shock and vibration loading. Such a
configuration may help reduce the likelihood of fretting, micro
pitting, and/or other types of wear in the rotor 754 and stator 752
bearing assemblies. This may be advantageous given the frequent
starts and stops of the system 700. Moreover, in an embodiment,
differences between the elasticity of superhard materials may help
reduce the likelihood of adhesion.
[0084] While the bearing apparatus including the rotor 754 and the
stator 752 is shown in a turbine application, the bearing apparatus
may be used in other diverse applications. For example, the bearing
apparatuses disclosed herein may be used in subterranean drilling
and motor assembly, motors, pumps, compressors, generators,
gearboxes, and other systems and apparatuses, or in any combination
of the foregoing.
[0085] While various aspects and embodiments have been disclosed
herein, other aspects and embodiments are contemplated. The various
aspects and embodiment disclosed herein are for purposes of
illustration and are not intended to be limiting. Additionally, the
words "including," having," and variants thereof (e.g., "includes"
and "has") as used herein, including the claims, shall be open
ended and have the same meaning as the word "comprising" and
variants thereof (e.g., "comprise" and "comprises").
* * * * *