U.S. patent application number 16/369632 was filed with the patent office on 2020-10-01 for bearing housing with flexible joint.
The applicant listed for this patent is PRATT & WHITNEY CANADA CORP.. Invention is credited to Guy LEFEBVRE, Remy SYNNOTT.
Application Number | 20200308982 16/369632 |
Document ID | / |
Family ID | 1000004024339 |
Filed Date | 2020-10-01 |
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United States Patent
Application |
20200308982 |
Kind Code |
A1 |
LEFEBVRE; Guy ; et
al. |
October 1, 2020 |
BEARING HOUSING WITH FLEXIBLE JOINT
Abstract
There is disclosed a gas turbine engine including a bearing
housing having at least two bearings axially spaced from one
another relative to a central axis. The bearing housing has a case
between the at least two bearings having a joint configured for
relative axial movement between the bearing supports. A method of
operating a bearing assembly including the bearing housing is also
disclosed.
Inventors: |
LEFEBVRE; Guy;
(St-Bruno-de-Montarville, CA) ; SYNNOTT; Remy;
(St-Jean-Sur Richelieu, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PRATT & WHITNEY CANADA CORP. |
Longueuil |
|
CA |
|
|
Family ID: |
1000004024339 |
Appl. No.: |
16/369632 |
Filed: |
March 29, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F05D 2220/32 20130101;
F05D 2240/54 20130101; F16C 2360/23 20130101; F05D 2240/91
20130101; F16C 19/16 20130101; F05D 2260/15 20130101; F01D 25/164
20130101; F01D 5/027 20130101 |
International
Class: |
F01D 25/16 20060101
F01D025/16 |
Claims
1. A gas turbine engine comprising a bearing housing having at
least two bearing supports axially spaced from one another relative
to a central axis, the bearing housing having a case between the at
least two bearing supports, the case having a joint configured for
relative axial movement between the at least two bearing
supports.
2. The bearing assembly of claim 1, wherein the joint comprises
flexible sheet metal portions.
3. The bearing assembly of claim 1, wherein the joint is defined by
a kink in the case of the bearing housing located between the at
least two bearing supports.
4. The bearing assembly of claim 3, wherein the kink is created by
an intersection of two frustoconical case sections of the case
providing a non-zero angle between the two frustoconical case
sections.
5. The bearing assembly of claim 4, wherein the kink is a
radially-outward most location of the case, the joint, in use,
radially moving toward the central axis upon an increase of an
axial distance between the at least two bearing supports.
6. The bearing assembly of claim 1, further comprising at least two
securing members each being axially aligned with a respective one
of the at least two bearing supports relative to the central axis,
the securing members secured to a casing of the gas turbine
engine.
7. The bearing assembly of claim 1, wherein the case defines
apertures for receiving bosses, the apertures being
circumferentially equidistantly distributed about the central
axis.
8. The bearing assembly of claim 7, wherein each of the apertures
is engaged by a respective one of an oil feed boss configured to be
fluidly connected to a lubricant system of the gas turbine engine
and for injecting lubricant in a bearing cavity, an oil scavenging
boss for draining used lubricant out of the bearing cavity, and a
non-functional boss.
9. The bearing assembly of claim 1, wherein the case is
axisymmetric relative to the central axis.
10. A gas turbine engine comprising a shaft rotatable about a
central axis, the shaft supported by at least two bearings
supported by at least two bearing supports of a bearing housing,
the bearing housing having a case including an elbow section
located between the at least two bearing supports, the case forming
a joint allowing relative axial movement between the at least two
bearing supports.
11. The gas turbine engine of claim 10, wherein the case is
axisymmetric relative to the central axis.
12. The gas turbine engine of claim 10, wherein the joint comprises
a flexible sheet metal portion.
13. The gas turbine engine of claim 10, wherein the joint is
defined by a kink in a case of the bearing housing located between
the at least two bearing supports.
14. The gas turbine engine of claim 13, wherein the kink is created
by intersection of two frustoconical case sections of the case
providing a non-zero angle between the two frustoconical case
sections.
15. The gas turbine engine of claim 13, wherein the kink is a
radially-outward most location on the case, the joint, in use,
radially moving toward the central axis upon an increase of an
axial distance between the at least two bearing supports.
16. The gas turbine engine of claim 10, further comprising at least
two securing members each being axially aligned with a respective
one of the at least two bearing supports relative to the central
axis, the securing members secured to a casing of the gas turbine
engine.
17. The gas turbine engine of claim 10, wherein the case defines
apertures for receiving bosses, the apertures being
circumferentially equidistantly distributed about the central
axis.
18. The gas turbine engine of claim 17, wherein each of the
apertures is engaged by a respective one of an oil feed boss
configured to be fluidly connected to a lubricant system of the gas
turbine engine and for injecting lubricant in a bearing cavity, an
oil scavenging boss for draining used lubricant out of the bearing
cavity, and a non-functional boss.
19. A method of operating a bearing assembly for a gas turbine
engine, comprising: supporting at least two bearings being axially
spaced apart relative to a central axis; receiving a first axial
load at least at one of the at least two bearings and receiving a
second axial load greater than the first axial load at the other of
the at least two of the bearings; and bending a case
interconnecting the at least two bearings to axially move the at
least two bearings relative to one another relative to the central
axis as a result of a difference between the first axial load and
the second axial load.
20. The method of claim 19, wherein bending the case includes
moving a joint connecting two case sections of the case toward the
central axis.
Description
TECHNICAL FIELD
[0001] The application relates generally to gas turbine engines
and, more particularly, to bearing housing assemblies used in such
engines.
BACKGROUND OF THE ART
[0002] In a gas turbine engine, a rotary shaft holding
compressor/fan and turbine blades is rotatably mounted within a
casing via bearings. The bearings are typically located radially
inwards relative to the annular flow path formed by duct walls of
the casing. A bearing housing usually encloses the bearings and
defines a bearing cavity for receiving lubricant for lubricating
the bearings. Due to the forces inherent to gas turbine engine
operation, and as they are the interface between shafts and a
support structure, the bearings are exposed lo loads, vibrations,
etc that may affect their performance over time.
SUMMARY
[0003] In one aspect, there is provided a gas turbine engine
comprising a bearing housing having at least two bearings axially
spaced from one another relative to a central axis, the bearing
housing having a case between the at least two bearings having a
joint configured for relative axial movement between the bearing
supports.
[0004] In another aspect, there is provided a gas turbine engine
comprising a shaft rotatable about a central axis, the shaft
supported by at least two bearings supported by a common bearing
housing, the bearing housing having a case including an elbow
section located between the at least two bearings forming a joint
allowing relative axial movement between the bearing supports.
[0005] In yet another aspect, there is provided a method of
operating a bearing assembly for a gas turbine engine, comprising:
supporting at least two bearings being axially spaced apart
relative to a central axis; receiving a first axial load at least
at one of the at least two bearings and receiving a second axial
load greater than the first axial load at the other of the at least
two of the bearings; and bending a case interconnecting the at
least two bearings to axially move the at least two bearings
relative to one another relative to the central axis as a result of
a difference between the first axial load and the second axial
load.
DESCRIPTION OF THE DRAWINGS
[0006] Reference is now made to the accompanying figures in
which:
[0007] FIG. 1 is a schematic cross-sectional view of a gas turbine
engine;
[0008] FIG. 2 is a schematic cross-sectional view of a portion of
the gas turbine engine of FIG. 1 in accordance with one
embodiment;
[0009] FIG. 3 is an enlarged view of a portion of FIG. 2;
[0010] FIG. 4 is a schematic three-dimensional view of a bearing
housing of the gas turbine engine of FIG. 1 in accordance with one
embodiment; and
[0011] FIG. 5 is a front view of the bearing housing of FIG. 4.
DETAILED DESCRIPTION
[0012] FIG. 1 illustrates a gas turbine engine 10 of a type
preferably provided for use in subsonic flight, generally
comprising in serial flow communication a fan 12 through which
ambient air is propelled, a compressor section 14 for pressurizing
the air, a combustor 16 in which the compressed air is mixed with
fuel and ignited for generating an annular stream of hot combustion
gases, and a turbine section 18 for extracting energy from the
combustion gases. The fan 12, the compressor section 14, and the
turbine section 18 are rotatable about a central axis 11.
[0013] The compressor section 14, fan 12 and turbine section 18
have rotating components which can be mounted on one or more shafts
20, 22, which, in this embodiment, rotate concentrically around the
central axis 11. Bearings 24 are used to provide smooth relative
rotation between a shaft (20 or 22) and casings 26, 28 (FIG. 2)
(non-rotating component), and/or between the two shafts 20, 22
which rotate at different speeds.
[0014] Referring now to FIG. 2, a cross-sectional view of a portion
of the turbine section 18 is illustrated. A bearing assembly is
generally shown at 100. The bearing assembly 100 is located
radially inwardly of vanes 18a of the turbine section 18 relative
to the central axis 11.
[0015] The bearing assembly 100 includes bearings 110 and a bearing
housing 120 enclosing the bearings 110. The bearing housing 120 is
used for defining a bearing cavity C circumferentially extending
around the axis 11. The bearing cavity C is used for receiving
lubricant from a lubrication system S for lubricating the bearings
110. The bearing 110 and the bearing housing 120 are described in
succession herein below.
[0016] Still referring to FIG. 2, two bearings 110 are shown and
are axially offset from each other relative to the central axis 11.
It is understood that the gas turbine engine 10 may include more
than two bearings. For the sake of clarity, only one of the two
bearings 110 is described herein below using the singular form, but
the description may apply to both of the bearings 110.
[0017] The bearing 110 is used to allow a rotation of the shaft 20
relative to the bearing housing 120 and to substantially maintain a
radial position of the shaft 20 relative to the casing 28 of the
gas turbine engine 10. The bearing 110 may include an inner race
112 secured to the shaft 20, an outer race 114 secured to the
bearing housing 120 and/or rolling elements 116 located radially
between the inner and outer races 112, 114. The rolling elements
116 may be spherically, cylindrically, frustoconically shaped,
among examples. Any suitable bearing known in the art may be
used.
[0018] Since the shaft 20 may rotate at a relatively high speed
relative to the casing 28, proper lubrication of the bearings 110
may be required. As aforementioned, the lubrication system S
injects the lubricant within the bearing cavity C. It might be
desirable to keep the lubricant within the bearing cavity C. This
function may be carried by the bearing housing 120 and sealing
members (not shown).
[0019] In the depicted embodiment, the bearing housing 120 includes
a case 122 that circumferentially extends all around the central
axis 11. The case 122 extends at least axially relative to the axis
11 and may span a distance between the two bearings 110.
[0020] Two bearing supports 124 (or more if more bearings are
present) are secured at axial extremities of the case 122. Each of
the two bearing supports 124 is in engagement with a respective one
of the outer races 114 of the bearings 110. The two bearing
supports 124 are stiffer than the case to be able to withstand
loads applied thereto from the shaft 22 via the bearing 110. In the
embodiment shown, a radial thickness of the two bearing supports
124 is greater than that of the case 122. The bearings 110, and the
bearing supports 124, may be spaced apart by an axial distance
greater than a diameter of the shaft 22. As shown, the axial
distance between the two bearing supports 124 is greater than a
chord length of the vanes 18a of the turbine section 18.
[0021] The bearing housing 120 further includes securing members
126 for attaching the bearing housing 120 to the casing 26 of the
gas turbine engine 10. In the embodiment shown, the securing
members 126 are flanges, also referred to as hairpins, 128
extending radially outwardly from the case 122. The flanges 128 may
extend circumferentially all around the central axis 11. In other
words, the flanges 128 may be annular walls. Securing members 126
may have other configurations, such as tabs, non-flange annular
walls, an annular bracket, etc.
[0022] The securing members 126 are configured to be secured to
connecting members 28a extending radially inwardly from the casing
28. In the embodiment shown, fasteners are used to secure the
securing members 126 (e.g., the flanges 128) to the connecting
members 28a of the engine casing 28. Other fixation means are
contemplated. In the embodiment shown, each of the securing members
126 is axially aligned with a respective one of the bearing
supports 124. In the depicted embodiment, the flanges 128 extend
radially outwardly from the bearing supports 124 relative to the
central axis 11.
[0023] In the depicted embodiment, each of the flanges 128 is
securable to a respective one of the connecting members 28a of the
casing 28. Interfaces I between the flanges 128a and the connecting
members 28a are located on sides of the flanges 128a that face
axially rearward relative to the central axis 11. This might allow
to insert the bearing housing 120 within the casing 28 in an axial
direction relative to the central axis 11.
[0024] In some cases, it might be advantageous to vary the
stiffness of the two bearing supports 124 of the bearing housing
120. However, increasing the stiffness of one of the two bearing
supports 124 may indirectly increase that of the other. Moreover,
if the two bearing supports 124 of the bearing housing 120 vary in
their respective stiffness, they might react differently to
temperature variations. In other words, if the bearing housing 120
is installed in the turbine section 18, one of the two bearing
supports 124 might subjected to different thermal expansion than
the other which might include thermal stresses. This phenomenon may
be enhanced by the high temperature gradients in the turbine
section 18. More specifically, the casing 28 might be more affected
to the temperature of exhaust gases circulating in the turbine
section 18 than the bearing housing 120 as the casing 28 is closer
to the exhaust gases. This might create thermal stress.
[0025] Still referring to FIG. 2, the case 122 of the bearing
housing 120 includes an elbow or joint 132 that allows relative
axial movement between the bearing supports 124 and between the
bearings 110. In the embodiment shown, the case 120 is axisymmetric
relative to the central axis 11, though the case 120 may not be
axisymmetric. In the depicted embodiment, the case is made of
flexible sheet metal.
[0026] The joint 132 may be defined by a kink 134 in the case 122.
In the depicted embodiment, the kink 134 is created by an
intersection of two generally continuous case sections 122a that
are joined together at the kink 134--in the context that the case
122 may be a monolithic piece. The case sections 122a may be
frustoconical. Each of the two case sections 122a extends from a
respective one of the bearing supports 124 toward the other of the
bearing supports 124. The two case sections 122a define an angle
.theta. at the kink 134. The angle .theta. between the two case
sections 122a is variable to allow the axial movements between the
at least two bearings 110. The angle .theta. is oriented radially
inward and is obtuse. In an embodiment, the angle .theta. is
greater than 90 degrees and less than 170 degrees. The kink 34 may
be referred to as a bend, a deflection, etc.
[0027] In the embodiment shown, the joint 132 is located at a
radially-outward most location of the case 122. The joint 132 is
able to move radially inwardly toward the central axis with an
increase of the angle .theta. and with an increase of an axial
distance relative to the central axis 11 between the two bearings
110. Stated differently, the case 122 is getting straighter when
the axial distance between the two bearings 110 increases.
[0028] Still referring to FIG. 2, as the case 122 is flexible at
the joint 132, the bearing supports 124 might be able to directly
transfer radial loads from one of the bearings 110 to the casing 28
of the gas turbine engine 10 without transferring said radial loads
to the other of the bearings 110.
[0029] Referring now to FIGS. 2-6, the case 122 defines apertures
122b configured for receiving bosses 136. In the embodiment shown,
the apertures 122b are circumferentially equidistantly distributed
about the central axis 11. Stated otherwise, a circumferential
distance taken along the central axis between two adjacent ones of
the apertures 122b and of the bosses 136 is constant. In other
words, the case 122 is axisymmetric with the bosses 136a, 136b,
136c. As shown more specifically on FIG. 5, the bosses and
apertures are spaced apart from one another by 120 degrees. The
bosses 136 may be welded on the case 122.
[0030] In the depicted embodiment, three apertures 122b are defined
through the case 122; each of the three apertures 122b being
engaged by a respective one of an oil feed boss 136a, an oil
scavenging boss 136b, and a non-functional boss 136c. The
non-functional boss 136c is merely a piece of metal and might not
connected to any other component of the engine 10. The
non-functional boss 136 may be used to even the stress distribution
by maintaining an axisymmetric architecture. In other words, a
weight distribution on the bearing housing 120 may be axisymmetric
because of the non-functional boss 136c.
[0031] As shown more clearly on FIGS. 3 and 5, the oil scavenging
boss 136b is located at a lower portion of the case 122 such that
lubricant may flow naturally by gravity toward the oil scavenging
boss 136b and the corresponding one of the apertures 122b.
[0032] Referring back to FIGS. 2-3, the two case sections 122a
slope radially outwardly toward the joint 132. The oil scavenging
boss 136b may be located proximate to the joint 132 such that oil
flows naturally against the case sections 122a toward the oil
scavenging boss 136b by gravity.
[0033] For operating the bearing assembly 100, a first axial load
is received at least at one of the at least two bearings 110 and a
second axial load greater than the first axial load is received at
the other of the at least two of the bearings; the case is bent to
axially move the at least two bearings relative to one another
relative to the central axis as a result of a difference between
the first axial load and the second axial load. In the depicted
embodiment, bending the case 122 includes moving the joint 132
connecting the two case sections 122a of the case toward the
central axis 11.
[0034] The disclosed bearing housing 120 might allow for an axial
thermal displacement in relation to the casing 28 of the engine 10.
In a particular embodiment, the disclosed housing 120 allows for a
dual bearing housing hairpin connection that support at least two
bearings 110 in a single housing 120. Having the bosses 136 evenly
distributed might allow for an uniform stress distribution all
around the bearing housing 120.
[0035] The above description is meant to be exemplary only, and one
skilled in the art will recognize that changes may be made to the
embodiments described without departing from the scope of the
invention disclosed. Still other modifications which fall within
the scope of the present invention will be apparent to those
skilled in the art, in light of a review of this disclosure, and
such modifications are intended to fall within the appended
claims.
* * * * *