U.S. patent application number 17/572791 was filed with the patent office on 2022-05-05 for bearing assembly with surface layer.
The applicant listed for this patent is Hamilton Sundstrand Corporation. Invention is credited to David J. Grulke, Steven Poteet.
Application Number | 20220136559 17/572791 |
Document ID | / |
Family ID | 1000006081294 |
Filed Date | 2022-05-05 |
United States Patent
Application |
20220136559 |
Kind Code |
A1 |
Poteet; Steven ; et
al. |
May 5, 2022 |
BEARING ASSEMBLY WITH SURFACE LAYER
Abstract
A bearing assembly is disclosed that includes a first component
with a first bearing surface, and a second component with a second
bearing surface. A fluid is disposed between the first bearing
surface and the second bearing surface supporting the first bearing
surface and the second bearing surface in a non-contact rotational
relationship. The first bearing surface, or the second bearing
surface, or both the first bearing surface and the second bearing
surface include a surface layer with solid lubricant 2D
nanoparticles in a matrix.
Inventors: |
Poteet; Steven; (Hamden,
CT) ; Grulke; David J.; (Tolland, CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hamilton Sundstrand Corporation |
Charlotte |
NC |
US |
|
|
Family ID: |
1000006081294 |
Appl. No.: |
17/572791 |
Filed: |
January 11, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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15401878 |
Jan 9, 2017 |
11221039 |
|
|
17572791 |
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Current U.S.
Class: |
384/112 |
Current CPC
Class: |
C10M 125/22 20130101;
C10M 2217/0443 20130101; F16C 33/1095 20130101; C10M 2201/041
20130101; F16C 17/024 20130101; C10N 2040/02 20130101; F16C 2240/48
20130101; C10M 2201/0413 20130101; F16C 17/102 20130101; C10N
2020/06 20130101; C10M 125/02 20130101; C10M 2201/087 20130101;
F16C 32/0633 20130101; C10M 2201/0623 20130101; F16C 33/107
20130101; C10M 2201/066 20130101; C10M 107/44 20130101; C10M
2201/0613 20130101; C10N 2050/08 20130101; C10M 125/26
20130101 |
International
Class: |
F16C 17/10 20060101
F16C017/10; F16C 17/02 20060101 F16C017/02; F16C 32/06 20060101
F16C032/06; C10M 107/44 20060101 C10M107/44; C10M 125/02 20060101
C10M125/02; C10M 125/26 20060101 C10M125/26; F16C 33/10 20060101
F16C033/10; C10M 125/22 20060101 C10M125/22 |
Claims
1.-17. (canceled)
18. A bearing comprising a support, a bump foil over the support, a
top foil over the bump foil, and a surface layer over the bump foil
comprising solid lubricant 2D nanoparticles in a matrix, said
nanoparticles having 1 to 20 atoms along a first dimension and
being present in the surface layer in a concentration of 35 wt. %
to 72 wt. % based on total weight of the surface layer.
19. The bearing of claim 18, wherein the solid lubricant 2D
nanoparticles comprise graphene, hexagonal boron nitride,
molybdenum disulfide or combinations thereof graphene.
20. The bearing of claim 18, wherein the solid lubricant 2D
nanoparticles have a thickness of 1 to 20 atomic layers and include
an x-y planar dimension of 10 nm to 25 .mu.m.
Description
BACKGROUND
[0001] Bearing assemblies are widely used to provide engagement
between a moving component or assembly (i.e., a rotor) and a
support or other structure that is stationary or that moves at a
different speed than the moving component or assembly. One
challenge faced by bearing assemblies is management of friction
between the moving and non-moving components or between components
moving at different speeds. Many bearing assemblies utilize one or
more rolling surfaces such as balls or other rollers disposed in a
raceway formed by race structures integrated with or attached to
the rotor and the support. Other bearing assemblies rely on
low-friction sliding surfaces for engagement between the rotor and
support. Another type of bearing assembly relies on the presence of
a fluid between the bearing surfaces to maintain the bearing
surfaces in a non-contact relationship. The fluid can be a liquid
or a gas, with the gas often provided under pressure sufficient to
maintain the bearing surfaces in a non-contact relationship. In
many cases, the fluid between the bearing surfaces is pressurized
air, and such bearings are commonly referred to as "air
bearings".
[0002] Non-contact bearing assemblies such as air bearings can
provide effective management of significant frictional forces to
the bearing surfaces. However, friction on the bearing surfaces is
not necessarily eliminated for all operational conditions. For
example, in the case of pressurized air supplied to an aerostatic
or hydrostatic bearing, any interruption of the pressurized fluid
source can subject the bearing surfaces to frictional contact.
Also, non-standard operating conditions such as an overload on the
bearing assembly can overwhelm the fluid buffer and force the
components into frictional contact. In the case of aerodynamic or
hydrodynamic bearings that rely on the motion of the bearing
components themselves or on connected components to generate or
pressurize the fluid buffer, the bearing surfaces can come into
frictional contact during commencement or termination of the
components' motion (i.e., startup or shutdown).
BRIEF DESCRIPTION
[0003] In some embodiments of this disclosure, a bearing assembly
comprises a first component comprising a first bearing surface, and
a second component comprising a second bearing surface. A fluid is
disposed between the first bearing surface and the second bearing
surface supporting the first bearing surface and the second bearing
surface in a non-contact rotational relationship. The first bearing
surface, or the second bearing surface, or both the first bearing
surface and the second bearing surface include a surface layer
comprising solid lubricant 2D nanoparticles in a matrix.
[0004] In some embodiments, a bearing comprises a support, a bump
foil over the support, a top foil over the bump foil, and a surface
layer over the bump foil comprising solid lubricant 2D
nanoparticles in a matrix.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] Subject matter of this disclosure is particularly pointed
out and distinctly claimed in the claims at the conclusion of the
specification. The foregoing and other features, and advantages of
the present disclosure are apparent from the following detailed
description taken in conjunction with the accompanying drawings in
which:
[0006] FIG. 1 is a partial cross-sectional view of an example
embodiment of a journal bearing;
[0007] FIG. 2 is a partial exploded view of an example embodiment
thrust bearing; and
[0008] FIG. 3 is a schematic cross-sectional view of an air cycle
machine.
DETAILED DESCRIPTION
[0009] With reference now to the Figures, FIG. 1 is a
cross-sectional view of an example embodiment of a fluid film
journal bearing assembly (journal bearing 100). The journal bearing
100 includes a journal sleeve 102 that defines an outer diameter
surface 104 and an inner diameter surface 106. The journal sleeve
102 is substantially cylindrical and is arranged about a central
axis. It should be noted that the journal sleeve can have a
conventional cylindrical shape, or can be shaped with a
weight-reduced profile, or configured as other shapes or
configurations, and FIG. 1 merely presents an exemplary
configuration of a journal bearing 100.
[0010] In FIG. 1, a number of foils are arranged inside the journal
sleeve 102. The journal bearing 100 includes a bump foil 108, an
intermediate foil 110, and a top foil 122. The bump foil 108, the
intermediate foil 110, and the top foil 112 are each formed from
thin sheets of material (e.g., nickel-based alloys, steel, or
similar materials) wrapped in a generally cylindrical shape and
positioned in a bore of the journal sleeve 102. The bump foil 108
is corrugated, allowing a working fluid and/or cooling fluid to
flow through the spaces formed between adjacent corrugations. The
bump foil 108 is positioned adjacent to the inner diameter surface
106 of the journal sleeve 102. The foils 108, 110, and 112 are
retained relative to the journal sleeve 102 with bent portions 114
that engage a key slot 116. A rotating component 118, such as a
shaft can be positioned inside the journal bearing 100, radially
inward from the top foil 112. The rotating component 118 is
typically in close proximity to the top foil 112, but for ease of
illustration is shown in a partial exploded view with an
exaggerated distance between the top foil 112 and the rotating
component 118. During operation, moving air generated by action of
the rotating component 118 urges pressurized air radially outward
against the compliant foil structure 108, 110, and 112 to create a
fluid air layer separating the rotating component 118 and the
journal bearing 100.
[0011] As further shown in FIG. 1, a surface layer 120, which is
exposed to a bearing surface of a rotating component, is disposed
over (in this case, radially inward from) the top foil 112. The
surface layer 120 comprises solid lubricant 2D nanoparticles in a
matrix. In some embodiments, the surface layer can have a thickness
in a range with a low end of 2 nm, 8, nm, or 12 nm, and a high end
of 65 nm, 40 nm, or 20 nm. All possible combinations of the
above-mentioned range endpoints (excluding impossible combinations
where a low endpoint would have a greater value than a high
endpoint) are explicitly included herein as disclosed ranges. The
surface layers discussed herein can be included as a surface layer
on either or both of the bearing surfaces of relative motion. For
example, in the case of the example embodiment such as FIG. 1
showing a bearing assembly comprising a rotating member 118 and a
journal bearing 100, the surface layer can be on the surface of the
bearing surface on the radially inner surface of top foil 112 as
shown for surface layer 120 in FIG. 1, or the surface layer can be
on the radially outer surface of the rotating member 118, or the
surface layer can be on the surface of the bearing surface on the
radially inner surface of top foil 112 as shown for surface layer
120 in FIG. 1 and on the radially outer surface of the rotating
member 118.
[0012] The matrix of a surface layer such as surface layer 120 can
include any sort of matrix material, including but not limited to
polymers, ceramics, metal, or matrix materials that can form a
continuous phase. In some embodiments, the matrix material
comprises a polyamide polymer, a polyimide polymer, or a copolymer
comprising polyamide or polyimide segments. In some embodiments,
the matrix material comprises a polyamide-polyimide copolymer.
Various application techniques for creation or application of the
surface layer can be utilized by the skilled person. For example, a
surface layer can be applied as a polymer coating by spray
application of a liquid or powder coating composition comprising a
polymer matrix material and dispersed solid lubricant 2D
nanoparticles followed by curing to coalesce and solidify the
coating. In some embodiments, the solid lubricant 2D nanoparticles
are present in the surface layer at a concentration in a range with
a low end of 35 wt. %, 45 wt. %, or 58 wt. %, and a high end of 72
wt. %, 68 wt. %, or 62 wt. %, based on the total coating solids.
All possible combinations of the above-mentioned range endpoints
(excluding impossible combinations where a low endpoint would have
a greater value than a high endpoint) are explicitly included
herein as disclosed ranges. The surface layer can also include
various other materials. For example, in the case of polymer
coatings, the surface layer can include various polymer coating
additives (e.g., curing agents, antioxidants, coating aids,
fillers, etc.).
[0013] Various materials can be utilized as solid lubricant 2D
nanoparticles. As used herein, the term "2D" includes particles
with a smallest dimension, or thickness, of 1 to 20 molecular
layers, and one or more anisotropic dimensions along lines or
planes that diverge from the thickness. In some embodiments, the
anisotropic dimensions can extend beyond 100 nm, although this is
not necessary. In some embodiments, the 2D nanoparticles can have
an aspect ratio, defined as the ratio of the largest dimension to
the smallest dimension of at least 10. In some embodiments, the 2D
nanoparticles can have an aspect ratio, defined as the ratio of the
largest dimension to the smallest dimension of at least 100. In
some embodiments, the 2D nanoparticles can have an even higher
aspect ratio of at least 2500. Higher levels of aspect ratios can
be obtained at relatively complete levels of exfoliation, including
to the level of a single molecular layer. As mentioned above, the
2D nanoparticles can have a thickness ranging from 1 to 20
molecular layers. In some embodiments, the 2D nanoparticles can
have a thickness ranging from 1 to 15 molecular layers. In some
embodiments, the 2D nanoparticles can have a thickness ranging from
1 to 10 molecular layers. In some embodiments, the 2D nanoparticles
can have a thickness ranging from 1 to 5 molecular layers. In some
embodiments, the 2D nanoparticles can have a thickness ranging from
1 to 4 molecular layers. In some embodiments, the 2D nanoparticles
can have a thickness ranging from 1 to 3 molecular layers. In some
embodiments, the 2D nanoparticles can have a thickness ranging from
1 to 2 molecular layers. In some embodiments, the 2D nanoparticles
can have a thickness of 1 molecular layer. In some embodiments, the
2D nanoparticles can have a have a mean diameter in a range with a
low end of 10 nm, 90 nm, or 1 .mu.m, and a high end of 13 .mu.m, 7
.mu.m, or 5 .mu.m. Mean diameter for 2D nanoparticles can be
determined using commercially available electron microscopy
measurement tools. All possible combinations of the above-mentioned
range endpoints (excluding impossible combinations where a low
endpoint would have a greater value than a high endpoint) are
explicitly included herein as disclosed ranges. As the term
"lubricant" is used herein with respect to the solid 2D
nanoparticles, the solid 2D nanoparticles are considered as
"lubricant" nanoparticles if the coating has a coefficient of
friction that is less than a coefficient of friction of a
comparison coating of the same matrix material but without the
solid 2D nanoparticles. Examples of materials for the solid
lubricant 2D nanoparticles include graphene, hexagonal boron
nitride, or molybdenum disulfide. In some embodiments, the surface
layer can include lubricant materials in addition to the solid
lubricant 2D nanoparticles. Examples of such additional solid
lubricant particles or nanoparticles include particles or
nanoparticles of materials such as graphene, hexagonal boron
nitride, or hexagonal molybdenum disulfide of different particle
sizes than the solid lubricant 2D nanoparticles.
[0014] Solid 2D nanoparticles can be prepared by various
techniques. Graphene, for example, can be prepared by different
techniques including chemical vapor deposition onto a substrate up
to a target thickness followed by removal of graphene from the
substrate. Solid 2D nanoparticles, including graphene, hexagonal
boron nitride, and hexagonal molybdenum disulfide, can also be
prepared by exfoliation of a parent molecular three-dimensional
material such as graphite, unexfoliated hexagonal boron nitride, or
unexfoliated hexaganol molybdenum disulfide. Various exfoliation
techniques can be used, including mechanical exfoliation, sonic
exfoliation, thermal exfoliation, or chemical exfoliation. Many
exfoliation techniques can be controlled (e.g., by controlling
duration, reaction conditions such as agitation speed or
temperature, or materials, or both duration and reaction conditions
or materials) to produce solid 2D nanoparticles with particle size
and configuration in a target range.
[0015] The bearing assembly shown in FIG. 1 is just one of many
possible example embodiments. Another example embodiment is shown
in FIG. 2, in which an exploded view is shown of an example
embodiment of a hydrodynamic fluid film thrust bearing assembly
("thrust bearing 200"), which represents another type of foil
hydrodynamic bearing. As is apparent from the Figures, the thrust
bearing 200 of FIG. 2 has a different construction than the journal
bearing 100 of FIG. 1. This is because journal bearings, such as
shown in FIG. 1, operate with radial loads, whereas thrust
bearings, as shown in FIG. 2, operate with axial loads. However,
both types of bearings operate similarly by employing hydrodynamic
fluid films, such as air or other fluids, to both provide bearing
lubricant and cooling.
[0016] In the example embodiment of FIG. 2, the thrust bearing 200
includes three layers, but may include more or fewer layers. A
first layer 202 comprises multiple arcuate top foils 204 that are
spaced circumferentially relative to one another about a central
axis. The top foils 204 are supported by a second layer 206 having
a corresponding number of arcuate bump foils 208 arranged
circumferentially beneath the top foils 204. The bump foils 208 are
corrugated to provide cushioning and accommodate a cooling airflow
through the thrust bearing 200. A third layer 210 is provided as an
annular main plate 212 that supports the bump foils 208. The three
layers 202, 206, and 210 can be secured to one another, for
example, by spot welding. A rotating component 214, such as a
thrust plate on an end of a rotating shaft can be positioned
adjacent to the top foils 204. The rotating component 214 is
typically in close proximity to the top foils 204, but for ease of
illustration is shown in a partial exploded view with an
exaggerated distance between the top foil 204 and the rotating
component 214. During operation, moving air generated by action of
the rotating component 214 urges pressurized air against the
compliant foil structure to create a fluid air layer separating the
rotating component 214 and the thrust bearing 200. As with the
journal bearing 100 of FIG. 1, the surface layer (not shown) can be
on the surface of the bearing surface on the radially inner surface
of top foil 204, or the surface layer can be on the radially outer
surface of the rotating component 214, or the surface layer can be
on the surface of the bearing surface on the radially inner surface
of top foil 204 and on the radially outer surface of the rotating
component 214.
[0017] In some embodiments, the above described hydrodynamic
bearings can be employed in an air cycle machine such as those
employed on aircraft. The hydrodynamic bearings provide a long
lasting bearing with minimal to no required maintenance. This is
because the bearings employ air as both a lubricating fluid and as
a cooling fluid, which means that separate lubricating or cooling
liquids are not typically required. An example embodiment of an air
cycle machine is shown in FIG. 3. As shown in FIG. 3, an air cycle
machine 300 is part of an environmental control system that is
configured to supply conditioned air, for example, to a cabin of an
aircraft. The air cycle machine 300 is a four-wheel air cycle
machine, with four rotors on a single shaft 304. The four rotors
are fixed together and are supported by bearing elements. There
are, thus, four bearings configured within the air cycle machine
300 which are arranged along an airflow passage 306, which is
represented by the path of arrows in FIG. 3. The air flow passage
306 provides air as both a lubricating fluid for the hydrodynamic
bearings and as a cooling air flow to remove heat generated by the
bearings during operation.
[0018] In the example configuration of FIG. 3, two of the four
bearings are thrust bearings and two are journal bearings, as
described above. The thrust bearings are located at the inlet side
of the airflow passage 306, with the journal bearings located
further downstream in the airflow passage 306. A first thrust
bearing 308 is configured as an outboard thrust bearing and a
second thrust bearing 310 is configured as an inboard thrust
bearing. After the thrust bearings 308 and 310, in the direction of
the airflow passage 306, a first journal bearing 312 is configured
as a turbine journal bearing and then, toward the outlet of the
airflow passage 306, a second journal bearing 314 is configured as
a fan journal bearing. The thrust bearings 308 and 310 are
configured to operate with axial loads, and the journal bearings
312 and 314 are configured to operate with radial loads within the
engine 302. As a non-limiting example, the air cycle machine 300
may operate at 20,000-50,000 RPM. However, other rotational speeds
of operation may be used.
[0019] While the present disclosure has been described in detail in
connection with only a limited number of embodiments, it should be
readily understood that the present disclosure is not limited to
such disclosed embodiments. Rather, the present disclosure can be
modified to incorporate any number of variations, alterations,
substitutions or equivalent arrangements not heretofore described,
but which are commensurate with the spirit and scope of the present
disclosure. Additionally, while various embodiments of the present
disclosure have been described, it is to be understood that aspects
of the present disclosure may include only some of the described
embodiments. Accordingly, the present disclosure is not to be seen
as limited by the foregoing description, but is only limited by the
scope of the appended claims.
* * * * *