U.S. patent application number 10/397482 was filed with the patent office on 2004-09-30 for diamond bearing with cooling/lubrication channels.
This patent application is currently assigned to Baker Hughes Incorporated. Invention is credited to John, Hendrik, Krafczyk, Andreas.
Application Number | 20040190804 10/397482 |
Document ID | / |
Family ID | 32989006 |
Filed Date | 2004-09-30 |
United States Patent
Application |
20040190804 |
Kind Code |
A1 |
John, Hendrik ; et
al. |
September 30, 2004 |
Diamond bearing with cooling/lubrication channels
Abstract
A thrust bearing comprises at least one diamond bearing segment,
wherein the segment has a front surface and a back surface. A
plurality of bearing pads extend a predetermined distance from the
front surface, each of the plurality of bearing pads has a load
surface substantially parallel to the front surface. The plurality
of bearing pads act cooperatively to provide a load bearing surface
area. The bearing pads are shaped and arranged in a predetermined
pattern to enhance the load carrying surface area, and the
predetermined pattern creates a plurality of flow micro-channels
between the bearing pads. In another aspect, a thrust bearing
comprises a diamond bearing surface, and a predetermined pattern of
cavities formed in the diamond bearing surface for providing a
fluid reservoir for lubricating and cooling the load surface.
Inventors: |
John, Hendrik; (Celle,
DE) ; Krafczyk, Andreas; (Celle, DE) |
Correspondence
Address: |
PAUL S MADAN
MADAN, MOSSMAN & SRIRAM, PC
2603 AUGUSTA, SUITE 700
HOUSTON
TX
77057-1130
US
|
Assignee: |
Baker Hughes Incorporated
Houston
TX
|
Family ID: |
32989006 |
Appl. No.: |
10/397482 |
Filed: |
March 26, 2003 |
Current U.S.
Class: |
384/420 |
Current CPC
Class: |
F16C 33/043 20130101;
F16C 2300/02 20130101; F16C 17/04 20130101; F16C 33/103 20130101;
F16C 33/1065 20130101; F16C 33/26 20130101; F16C 2206/04 20130101;
F16C 2240/42 20130101 |
Class at
Publication: |
384/420 |
International
Class: |
F16C 017/04 |
Claims
What is claimed is:
1. A diamond thrust bearing, comprising: a. at least one diamond
bearing segment, said segment having a front surface and a back
surface; and b. a plurality of bearing pads extending a
predetermined distance from said front surface, each of said
plurality of bearing pads having a load surface substantially
parallel to said front surface, said plurality of bearing pads
acting cooperatively to provide a load bearing surface area, said
bearing pads shaped and arranged in a predetermined pattern to
enhance the load carrying surface area, said predetermined pattern
creating a plurality of flow micro-channels between said bearing
pads.
2. The thrust bearing of claim 1, wherein the plurality of bearing
pads are integral with the bearing segment.
3. The thrust bearing of claim 1, wherein the plurality of bearing
pads comprise shaped diamond inserts mounted in said front
surface.
4. The thrust bearing of claim 1, further comprising at least one
flow macro-channel providing fluid to cool and lubricate said
bearing pads.
5. The thrust bearing of claim 1, further comprising a second
predetermined pattern formed on said back surface of said at least
one diamond bearing segment for enhancing attachment to a support
ring.
6. The thrust bearing of claim 1, wherein the plurality of bearing
pads are formed into said bearing segment by a pressing
operation.
7. The thrust bearing of claim 1, wherein the plurality of bearing
pads are formed into said bearing segment by at least one of (i)
electric discharge machining and (ii) laser ablation operation.
8. The thrust bearing of claim 1, wherein the flow channels are
formed to have a predetermined shape to reduce stresses at an
intersection of said bearing element and said front surface.
9. The thrust bearing of claim 1, wherein at least one edge of said
load surfaces is shaped to enhance hydrodynamic lubrication of said
load surface.
10. The thrust bearing of claim 1, wherein each of the plurality of
bearing pads has at least one cavity formed in said load surface of
said bearing pad for providing a fluid reservoir for lubricating
said load surface.
11. The thrust bearing of claim 4, wherein the at least one
macro-flow channel is located proximate at least one of (i) the
front surface of said bearing segment and (ii) the back surface of
said bearing segment.
12. A diamond thrust bearing, comprising: a. a diamond bearing
surface; and b. a predetermined pattern of cavities formed in said
diamond bearing surface for providing a fluid reservoir for
lubricating said load surface.
13. A method of increasing the load capacity of a diamond bearing,
comprising: a. providing at least one diamond bearing segment
having a front surface and a back surface; and b. disposing a
plurality of bearing pads having a predetermined shape in a
predetermined pattern in the front surface of said at least one
diamond bearing segment, said predetermined shape and said
predetermined pattern substantially increasing a load bearing
surface area of said diamond bearing, said predetermined shape and
said predetermined pattern creating a plurality of flow
micro-channels between said bearing pads for cooling said diamond
bearing.
14. The method of claim 13, wherein the step of disposing a
plurality of bearing pads having a predetermined shape in a
predetermined pattern in the front surface of said at least one
diamond bearing segment includes forming said plurality of bearing
pads as an integral part of said at least one diamond bearing
segment.
15. The method of claim 13, wherein the step of disposing a
plurality of bearing pads having a predetermined shape in a
predetermined pattern in the front surface of said at least one
diamond bearing segment includes disposing shaped diamond inserts
in said front surface.
16. The method of claim 13, further comprising forming a second
predetermined pattern on the back surface of said diamond bearing
segment for attachment to a support ring.
17. The method of claim 13, further comprising disposing at least
one flow macro-channel proximate at least one of (i) the front
surface of said diamond bearing segment and (ii) the back surface
of said diamond bearing segment.
18. The method of claim 13, further comprising forming at least one
cavity in a load surface of each of said plurality of bearing pads
for providing a fluid reservoir.
19. The method of claim 13, further comprising shaping at least one
edge of a load surface of each of said plurality of bearing pads to
enhance hydrodynamic lubrication of said load surface.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to thrust bearings and more
particularly to diamond bearing segments with cooling and
lubrication channels.
[0003] 2. Description of the Related Art
[0004] Diamond bearings have found application in oil drilling and
other environments demanding high load carrying ability under
extreme wear conditions. As used herein, the term diamond includes
synthetic diamond such as polycrystalline diamond. When used as a
thrust bearing, a pair of load carrying structures containing
diamond pads, also called inserts, are arranged in opposition to
bear against one another. One such common arrangement for a thrust
bearing is shown in FIG. 1, where a load ring 1 has a number of
individual diamond bearing inserts 2 disposed concentrically
therein. The thrust load is carried by the bearing surface 3 of
each insert.
[0005] The load carrying capacity of such a bearing is limited by
the frictional heat build up in the diamond bearing inserts. The
heat buildup is related to the unit area loading of the bearing
insert and to the availability of cooling mechanisms to remove the
heat generated. A thermal limit is eventually reached beyond which
the inserts begin to degrade and ultimately may disintegrate.
Replacement of any bearing in a downhole environment is undesirable
due to the expense and downtime involved in pulling and repairing
such equipment.
[0006] The methods and apparatus of the present invention overcome
the foregoing disadvantages of the prior art by providing a novel
bearing having an increased surface area for lowering the unit
loading and integral flow channels for cooling the bearing.
SUMMARY OF THE INVENTION
[0007] The present invention contemplates a novel diamond bearing
having an increased surface area for lowering the unit loading and
integral flow channels for cooling the bearing.
[0008] In one aspect of the invention, a thrust bearing comprises
at least one diamond bearing segment, wherein the segment has a
front surface and a back surface. A plurality of bearing pads
extend a predetermined distance from the front surface, each of the
plurality of bearing pads has a load surface substantially parallel
to the front surface. The plurality of bearing pads act
cooperatively to provide a load bearing surface area. The bearing
pads are shaped and arranged in a predetermined pattern to enhance
the load carrying surface area, and the predetermined pattern
creates a plurality of flow micro-channels between the bearing
pads.
[0009] In another aspect, a thrust bearing comprises a diamond
bearing surface, and a predetermined pattern of cavities formed in
the diamond bearing surface for providing a fluid reservoir for
lubricating and cooling the load surface.
[0010] Examples of the more important features of the invention
thus have been summarized rather broadly in order that the detailed
description thereof that follows may be better understood, and in
order that the contributions to the art may be appreciated. There
are, of course, additional features of the invention that will be
described hereinafter and which will form the subject of the claims
appended hereto.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] For detailed understanding of the present invention,
references should be made to the following detailed description of
the preferred embodiment, taken in conjunction with the
accompanying drawings, in which like elements have been given like
numerals, wherein:
[0012] FIG. 1 is a schematic drawing showing a prior art diamond
bearing;
[0013] FIG. 2A is a schematic drawing of a diamond bearing assembly
according to one preferred embodiment of the present invention;
[0014] FIG. 2B is a cross section of a portion of a bearing
assembly as depicted in FIG. 2A;
[0015] FIG. 2C is a schematic drawing of an interface between
moving bearing surfaces according to one embodiment of the present
invention;
[0016] FIG. 3 is a schematic drawing of a diamond bearing segment
according to one embodiment of the present invention;
[0017] FIG. 4 is a schematic drawing of a diamond bearing according
to one embodiment of the present invention;
[0018] FIG. 5 is a schematic drawing of a diamond bearing segment
having a hexagonal pattern of bearing pads according to one
embodiment of the present invention;
[0019] FIG. 6 is a schematic drawing of a diamond bearing segment
having a rhomboidal pattern of bearing pads according to one
embodiment of the present invention;
[0020] FIG. 7 is a schematic drawing of a diamond bearing segment
having a hexagonal pattern of bearing pads and a macro-channel
according to one embodiment of the present invention;
[0021] FIG. 8 is a schematic drawing of a diamond bearing segment
having a triangular pattern of bearing pads according to one
embodiment of the present invention;
[0022] FIG. 9 is a schematic drawing of a diamond bearing segment
having a circular or button pattern of bearing pads according to
one embodiment of the present invention;
[0023] FIG. 10 is a schematic drawing of a diamond bearing segment
having a rhomboidal pattern of bearing pads where each pad has a
cavity according to one embodiment of the present invention;
[0024] FIG. 11 is a schematic drawing of a diamond bearing segment
having a diamond bearing surface with a pattern of fluid holding
cavities in the surface according to one embodiment of the present
invention;
[0025] FIG. 12 is a schematic drawing of a diamond bearing segment
having a diamond bearing surface with a pattern of annular fluid
holding cavities in the surface according to one embodiment of the
present invention; and
[0026] FIG. 13 is a schematic drawing of a diamond bearing assembly
having cooling channels located beneath at least one diamond
bearing segment according to one embodiment of the present
invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0027] In one preferred embodiment, a diamond bearing assembly 4,
FIG. 2A, has multiple bearing segments 5 attached to a bearing
support ring 15, see FIG. 2B. A pattern of bearing pads 8 are
disposed in the front surface 12 of the bearing segment 5 and each
bearing pad 8 has an associated load surface 9. The bearing pads 8
are triangularly shaped such that the total area of all the load
surfaces 9 of bearing assembly 4 is substantially greater than the
corresponding load surface area of the prior art bearing of FIG. 1.
The bearing pads 8 are spaced such that flow micro-channels 11 are
created between the bearing pads 8. The micro-channels 11 provide a
path for a fluid to flow for cooling and lubricating the bearing
pads 8. As will be appreciated by one skilled in the art, the outer
housings (not shown) surrounding and supporting such a bearing may
force the cooling/lubricating fluid to flow from an outer diameter
18 of the bearing support ring 15 to an inner diameter 19 as shown
in FIG. 2A. Alternatively, the fluid may be forced to flow from the
inner diameter to the outer diameter.
[0028] The multiple bearing segments 5 are arranged on support ring
15 such that macro-channels 21 are formed between the bearing
segments 5 to provide a larger volume of coolant flow through the
bearing assembly 4. The macro-channels may be sized, using
techniques known in the art, to provide a predetermined pressure
differential across the bearing assembly thereby ensuring a fluid
flow through the bearing micro-channels sufficient to cool and
lubricate the bearing pads 8.
[0029] FIG. 2B shows a section through a bearing section A-A of
FIG. 2A in which the bearing pads 8 are integral with the bearing
segment 5. The bearing surface 9 extends a predetermined distance
from the surface 12. In this preferred embodiment, as shown in FIG.
2B, the entire bearing segment 5 is made of a diamond material,
such as for example, polycrystalline diamond. The bearing pads 8
may be press formed during the manufacture of bearing segment 5.
Alternatively, the bearing pads may be formed by removing material
from a formed diamond surface using techniques known in the art.
Such techniques include, but are not limited to, electric discharge
machining (EDM) and laser ablation techniques. The removal of such
material results in the raised pads and the interrelated
micro-channels.
[0030] The multiple bearing segments 5 are bonded to the bearing
ring 15 using any of a number of techniques known in the art. Such
bonding techniques include, but are not limited to, brazing,
sintering, and diffusion bonding. The bearing ring is commonly a
tungsten carbide material. Alternatively, a steel ring may be
used.
[0031] In one preferred embodiment, the back side of the bearing
segment 5 is formed to have a pattern of locking pads 16 extending
from back surface 14, see FIG. 2B. The locking pads act to improve
the bonding of the bearing segments 5 to the bearing ring 15. The
pattern of locking pads 16 may be similar to the pattern of bearing
pads 8. Alternatively, the pattern of locking pads 16 may be
determined using available numerical modeling techniques such that
the pattern of locking pads 16 acts to reduce stress concentrations
induced in bearing segment 5 by the compressional loading on
bearing pads 8 and the thermal stresses induced by the frictional
heating of the bearing pads 8. Such numerical modeling techniques,
such as finite element analysis, are known to one skilled in the
art and commercial packages are available for performing such an
analysis. Such an analysis is application dependent on the size,
shape, and loading characteristics of such a bearing system and a
locking pad pattern shape may be determined without undue
experimentation by one skilled in the art.
[0032] The bottom comers 20 of micro-channels 11, see FIG. 2B, may
be formed to reduce stress concentration at the corners. Such
comers 20 are commonly formed with a predetermined radius to reduce
such stress concentrations. The actual shape may be determined
using the analytical modeling techniques described previously. In
one preferred embodiment, the comer 20 has a radius substantially
equal to half of the width of micro-channel 11.
[0033] In another preferred embodiment, an upper edge 21(see FIGS.
2B, 2C) of bearing pad 8 is formed to provide an entrance ramp such
that fluid 22 is forced into the interface 23 by the relative
motion of mating bearing 30. This action acts to lubricate the
bearing and to draw heat away from the bearing surfaces 9. The form
of the upper edge 21 may be a chamfer, a radius, or any other
suitable shape that provides a wedging action to the fluid 22.
[0034] The bearing segments previously discussed with respect to
FIGS. 2A, B, C and 3, have bearing pads 8 as an integral part of
bearing segment 5. Alternatively, the bearing pads 8 may be
individual shaped diamond inserts that are bonded or captured in a
metallic matrix bearing ring using techniques known in the art.
Commonly, such a metallic matrix is a tungsten carbide
material.
[0035] In one preferred embodiment, see FIG. 4, a diamond bearing
45 is shown with a plurality of hexagonal bearing pads 41 arranged
in a concentric pattern on bearing ring 40. Micro-channels 42 are
formed between the bearing pads 41. The bearing pads 41 are
integral to the bearing ring 40 and are formed using any of the
techniques described above.
[0036] FIGS. 5-9 show other examples of patterns and shapes of
diamond bearing segments similar to that shown in FIG. 2. FIG. 5
shows a bearing segment 50 having a hexagonal pattern of bearing
pads 51 and flow micro-channels 52. FIG. 6 shows a bearing segment
60 having rhomboidal pattern of bearing pads 61 and flow
micro-channels 62. FIG. 7 shows a bearing segment 70 having a
hexagonal pattern similar to that of FIG. 5 but with a
macro-channel 73 extending across the bearing segment 70 to provide
additional fluid flow to the bearing pads 51. FIG. 8 shows a
bearing segment 80 having a triangular pattern that is a variation
of that shown in FIG. 2. FIG. 9 shows a bearing segment 90 having a
spaced pattern of circular, or button, shaped bearing pads 91 and
flow micro-channels 92.
[0037] FIG. 10 shows a bearing segment 100 having bearing pads 101
and flow micro-channels 102. A cavity 103 is formed in bearing
surface 104 of each bearing pad 101. The cavity 103 acts as a fluid
reservoir and acts to help provide fluid into the bearing interface
23 (see FIG. 2C) to lubricate and cool the bearing pads 101.
[0038] The exemplary bearings described above have bearing pads
integrally formed with the bearing segment. . Alternatively, the
bearing pads may be individual shaped diamond inserts that are
bonded or captured in a metallic matrix bearing ring using
techniques known in the art. Commonly, such a metallic matrix is a
tungsten carbide material.
[0039] FIG. 11 shows a diamond segment 110 having a continuous
diamond surface 112 and a pattern of fluid cavities 111 disposed in
the surface 112. The cavities 111 act as fluid reservoirs to
lubricate and cool the bearing surface 112. FIG. 12 shows a diamond
segment 120 having a continuous diamond surface 122 and a pattern
of annular fluid cavities 121 disposed in the surface 122. The
cavities 121 act as fluid reservoirs to lubricate and cool the
bearing surface 122.
[0040] In another preferred embodiment, FIG. 13 shows a portion of
a bearing assembly 139 having bearing segment 130, similar to those
described previously Bearing segment 130 has bearing pads 131 and
flow micro-channels 132. Bearing segment 130 is bonded to bearing
ring 135 that has macro flow channels 133, formed therein, for
flowing fluid 134 through the channels 134 and cooling the back
side of bearing segment 130. The number and shape of such flow
channels 133 may be determined, without undue experimentation, from
analytical methods previously described to provide adequate cooling
to the bearing pads 131 to prevent degradation.
[0041] It will be appreciated by one skilled in the art that all of
the exemplary bearing surfaces described herein, have substantially
greater bearing surface area than that of prior art bearings.
[0042] The foregoing description is directed to particular
embodiments of the present invention for the purpose of
illustration and explanation. It will be apparent, however, to one
skilled in the art that many modifications and changes to the
embodiment set forth above are possible. It is intended that the
following claims be interpreted to embrace all such modifications
and changes.
* * * * *