U.S. patent application number 13/346236 was filed with the patent office on 2012-05-03 for tapered bearings.
Invention is credited to Michael E. McCune, Lawrence E. Portlock.
Application Number | 20120102971 13/346236 |
Document ID | / |
Family ID | 38670975 |
Filed Date | 2012-05-03 |
United States Patent
Application |
20120102971 |
Kind Code |
A1 |
McCune; Michael E. ; et
al. |
May 3, 2012 |
TAPERED BEARINGS
Abstract
A gear support assembly for a turbine engine includes an
epicyclic gear arrangement and a first tapered bearing and a second
tapered bearing spaced apart from the first tapered bearing. The
first tapered bearing and the second tapered bearing are arranged
axially forward of the epicyclic gear arrangement and support the
epicyclic gear arrangement.
Inventors: |
McCune; Michael E.;
(Colchester, CT) ; Portlock; Lawrence E.;
(Bethany, CT) |
Family ID: |
38670975 |
Appl. No.: |
13/346236 |
Filed: |
January 9, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11504220 |
Aug 15, 2006 |
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13346236 |
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Current U.S.
Class: |
60/805 ;
475/331 |
Current CPC
Class: |
F16H 57/0458 20130101;
F16H 57/08 20130101; Y10T 29/49462 20150115; F05D 2240/70 20130101;
F16D 1/076 20130101; F05D 2240/55 20130101; F16H 1/28 20130101;
F02C 7/36 20130101; F16H 57/042 20130101; F05D 2260/40311 20130101;
F05D 2260/98 20130101; F16H 57/0482 20130101; F01D 5/027 20130101;
F16H 57/0402 20130101; F01D 25/18 20130101; F16H 57/0421 20130101;
F05D 2260/34 20130101; F02C 7/28 20130101; F16H 57/0424 20130101;
F16H 57/043 20130101; F16H 57/0486 20130101 |
Class at
Publication: |
60/805 ;
475/331 |
International
Class: |
F02C 7/36 20060101
F02C007/36; F02C 3/04 20060101 F02C003/04; F16H 57/08 20060101
F16H057/08 |
Claims
1. A gear support assembly for a turbine engine, comprising: an
epicyclic gear arrangement; a first tapered bearing and a second
tapered bearing spaced apart from the first tapered bearing, the
first tapered bearing and the second tapered bearing being arranged
axially forward of the epicyclic gear arrangement and supporting
the epicyclic gear arrangement.
2. The gear support assembly as recited in claim 1, wherein the
first tapered bearing and the second tapered bearing are located
radially inwards from a radially outer surface of the epicyclic
gear arrangement.
3. The gear support assembly as recited in claim 1, wherein the
first tapered bearing and the second tapered bearing are located
radially outwards of a radially inner surface of the epicyclic gear
arrangement.
4. The gear support assembly as recited in claim 1, including a
support arm extending forward from the epicyclic gear arrangement,
at least one of the first tapered bearing and the second tapered
bearing being mounted on the support arm.
5. The gear support assembly as recited in claim 4, wherein the
support arm is connected at one end at a radially outer location of
the epicyclic gear arrangement.
6. The gear support assembly as recited in claim 1, wherein at
least one of the first tapered bearing and the second tapered
bearing includes a cylindrical roller element.
7. The gear support assembly as recited in claim 6, wherein the
cylindrical roller element is supported on a tapered race.
8. The gear support assembly as recited in claim 1, wherein the
first tapered bearing and the second tapered bearing are spaced an
equivalent radial distance from a central axis of the epicyclic
gear arrangement.
9. The gear support assembly as recited in claim 1, wherein the
first tapered bearing includes a first roller element defining a
first rotational axis and the second tapered bearing includes a
second roller element defining a second rotational axis such that
the first rotational axis and the second rotational axis intersect
at a position that is radially inwards from the first roller
element and the second roller element.
10. The gear support assembly as recited in claim 1, wherein the
first tapered bearing includes a first roller element defining a
first rotational axis and the second tapered bearing includes a
second roller element defining a second rotational axis such that
the first rotational axis and the second rotational axis intersect
at a position that is radially inwards from a central axis of the
epicyclic gear arrangement.
11. A turbine engine comprising: a compressor section; a combustor
arranged in fluid receiving communication with the compressor
section; a turbine section arranged in fluid receiving
communication with the combustor; an epicyclic gear arrangement
coupled to be driven by the turbine section; and a first tapered
bearing and a second tapered bearing spaced apart from the first
tapered bearing, the first tapered bearing and the second tapered
bearing being arranged axially forward of the epicyclic gear
arrangement and supporting the epicyclic gear arrangement.
12. The turbine engine as recited in claim 11, including a fan
located axially forward of the compressor section, wherein a
forward one of the first tapered bearing and the second tapered
bearing is located at an equivalent axial position of the fan.
13. The turbine engine as recited in claim 11, including a fan
located axially forward of the compressor section, wherein a
forward one of the first tapered bearing and the second tapered
bearing is located at an equivalent axial position of the fan and a
rear one of the first tapered bearing and the second tapered
bearing is located at a non-equivalent axial position of the
fan.
14. The turbine engine as recited in claim 11, wherein the first
tapered bearing and the second tapered bearing are located radially
inwards from a radially outer surface of the epicyclic gear
arrangement.
15. The turbine engine as recited in claim 11, including a support
arm extending forward from the epicyclic gear arrangement, at least
one of the first tapered bearing and the second tapered bearing
being mounted on the support arm.
16. The turbine engine as recited in claim 15, wherein the support
arm is connected at one end at a radially outer location of the
epicyclic gear arrangement.
17. The turbine engine as recited in claim 11, wherein at least one
of the first tapered bearing and the second tapered bearing
includes a second cylindrical roller element.
18. The turbine engine as recited in claim 17, wherein the
cylindrical roller element is supported on a tapered race.
19. The turbine engine as recited in claim 11, wherein the first
tapered bearing and the second tapered bearing are spaced an
equivalent radial distance from a central axis of the epicyclic
gear arrangement.
20. The turbine engine as recited in claim 11, wherein the first
tapered bearing includes a first roller element defining a first
rotational axis and the second tapered bearing includes a second
roller element defining a second rotational axis such that the
first rotational axis and the second rotational axis intersect at a
position that is radially inwards from the first roller element and
the second roller element.
21. The turbine engine as recited in claim 11, wherein the first
tapered bearing includes a first roller element defining a first
rotational axis and the second tapered bearing includes a second
roller element defining a second rotational axis such that the
first rotational axis and the second rotational axis intersect at a
position that is radially inwards from a central axis of the
epicyclic gear arrangement.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present disclosure is a continuation of U.S. patent
application Ser. No. 11/504,220, filed Aug. 16, 2006.
BACKGROUND OF THE INVENTION
[0002] This invention relates to a ring gear used in an epicyclic
gear train of a gas turbine engine.
[0003] Gas turbine engines typically employ an epicyclic gear train
connected to the turbine section of the engine, which is used to
drive the turbo fan. In a typical epicyclic gear train, a sun gear
receives rotational input from a turbine shaft through a compressor
shaft. A carrier supports intermediate gears that surround and mesh
with the sun gear. A ring gear surrounds and meshes with the
intermediate gears. In arrangements in which the carrier is fixed
against rotation, the intermediate gears are referred to as "star"
gears and the ring gear is coupled to an output shaft that supports
the turbo fan.
[0004] Typically, the ring gear is connected to the turbo fan shaft
using a spline ring. The spline ring is secured to a flange of the
turbo fan shaft using circumferentially arranged bolts. The spline
ring includes splines opposite the flange that supports a splined
outer circumferential surface of the ring gear. The ring gear
typically includes first and second portions that provide teeth
facing in opposite directions, which mesh with complimentary
oppositely facing teeth of the star gears.
[0005] An epicyclic gear train must share the load between the
gears within the system. As a result, the splined connection
between the ring gear and spline ring is subject to wear under high
loads and deflection. Since the spline connection requires radial
clearance, it is difficult to get a repeatable balance of the turbo
fan assembly. Balance can also deteriorate over time with spline
wear.
SUMMARY OF THE INVENTION
[0006] A gear support assembly for a turbine engine according to an
exemplary aspect of the present disclosure comprises an epicyclic
gear arrangement, a first tapered bearing and a second tapered
bearing spaced apart from the first tapered bearing, the first
tapered bearing and the second tapered bearing being arranged
axially forward of the epicyclic gear arrangement and supporting
the epicyclic gear arrangement.
[0007] In a further non-limiting embodiment of any of the foregoing
assembly embodiments, the first tapered bearing and the second
tapered bearing are located radially inwards from a radially outer
surface of the epicyclic gear arrangement.
[0008] In a further non-limiting embodiment of any of the foregoing
assembly embodiments, the first tapered bearing and the second
tapered bearing are located radially outwards of a radially inner
surface of the epicyclic gear arrangement.
[0009] A further non-limiting embodiment of any of the foregoing
assembly embodiments includes a support arm extending forward from
the epicyclic gear arrangement, and at least one of the first
tapered bearing and the second tapered bearing is mounted on the
support arm.
[0010] In a further non-limiting embodiment of any of the foregoing
assembly embodiments, the support arm is connected at one end at a
radially outer location of the epicyclic gear arrangement.
[0011] In a further non-limiting embodiment of any of the foregoing
assembly embodiments, at least one of the first tapered bearing and
the second tapered bearing includes a cylindrical roller
element.
[0012] In a further non-limiting embodiment of any of the foregoing
assembly embodiments, the cylindrical roller element is supported
on a tapered race.
[0013] In a further non-limiting embodiment of any of the foregoing
assembly embodiments, the first tapered bearing and the second
tapered bearing are spaced an equivalent radial distance from a
central axis of the epicyclic gear arrangement.
[0014] In a further non-limiting embodiment of any of the foregoing
assembly embodiments, the first tapered bearing includes a first
roller element defining a first rotational axis and the second
tapered bearing includes a second roller element defining a second
rotational axis such that the first rotational axis and the second
rotational axis intersect at a position that is radially inwards
from the first roller element and the second roller element.
[0015] In a further non-limiting embodiment of any of the foregoing
assembly embodiments, the first tapered bearing includes a first
roller element defining a first rotational axis and the second
tapered bearing includes a second roller element defining a second
rotational axis such that the first rotational axis and the second
rotational axis intersect at a position that is radially inwards
from a central axis of the epicyclic gear arrangement.
[0016] A gas turbine engine according to an exemplary aspect of the
present disclosure comprises a compressor section, a combustor
arranged in fluid receiving communication with the compressor
section, a turbine section arranged in fluid receiving
communication with the combustor, an epicyclic gear arrangement
coupled to be driven by the turbine section and a first tapered
bearing and a second tapered bearing spaced apart from the first
tapered bearing, the first tapered bearing and the second tapered
bearing being arranged axially forward of the epicyclic gear
arrangement and supporting the epicyclic gear arrangement.
[0017] A further non-limiting embodiment of any of the foregoing
embodiments includes a fan located axially forward of the
compressor section, wherein a forward one of the first tapered
bearing and the second tapered bearing is located at an equivalent
axial position of the fan.
[0018] A further non-limiting embodiment of any of the foregoing
embodiments includes a fan located axially forward of the
compressor section, wherein a forward one of the first tapered
bearing and the second tapered bearing is located at an equivalent
axial position of the fan and a rear one of the first tapered
bearing and the second tapered bearing is located at a
non-equivalent axial position of the fan.
[0019] In a further non-limiting embodiment of any of the foregoing
embodiments, the first tapered bearing and the second tapered
bearing are located radially inwards from a radially outer surface
of the epicyclic gear arrangement.
[0020] A further non-limiting embodiment of any of the foregoing
embodiments includes a support arm extending forward from the
epicyclic gear arrangement, and at least one of the first tapered
bearing and the second tapered bearing being mounted on the support
arm.
[0021] In a further non-limiting embodiment of any of the foregoing
embodiments, the support arm is connected at one end at a radially
outer location of the epicyclic gear arrangement.
[0022] In a further non-limiting embodiment of any of the foregoing
embodiments, at least one of the first tapered bearing and the
second tapered bearing includes a second cylindrical roller
element.
[0023] In a further non-limiting embodiment of any of the foregoing
embodiments, the cylindrical roller element is supported on a
tapered race.
[0024] In a further non-limiting embodiment of any of the foregoing
embodiments, the first tapered bearing and the second tapered
bearing are spaced an equivalent radial distance from a central
axis of the epicyclic gear arrangement.
[0025] In a further non-limiting embodiment of any of the foregoing
embodiments, the first tapered bearing includes a first roller
element defining a first rotational axis and the second tapered
bearing includes a second roller element defining a second
rotational axis such that the first rotational axis and the second
rotational axis intersect at a position that is radially inwards
from the first roller element and the second roller element.
[0026] In a further non-limiting embodiment of any of the foregoing
embodiments, the first tapered bearing includes a first roller
element defining a first rotational axis and the second tapered
bearing includes a second roller element defining a second
rotational axis such that the first rotational axis and the second
rotational axis intersect at a position that is radially inwards
from a central axis of the epicyclic gear arrangement.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 is a partial cross-sectional view of a front portion
of a gas turbine engine illustrating a turbo fan, epicyclic gear
train and a compressor section.
[0028] FIG. 2A is an enlarged cross-sectional view of the epicyclic
gear train shown in FIG. 1.
[0029] FIG. 2B is an expanded view of a portion of FIG. 1;
[0030] FIG. 3 is an enlarged cross-sectional view of an example
ring gear similar to the arrangement shown in FIG. 2.
[0031] FIG. 4 is a view of the ring gear shown in FIG. 3 viewed in
a direction that faces the teeth of the ring gear in FIG. 3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0032] A portion of a gas turbine engine 10 is shown schematically
in FIG. 1. The turbine engine 10 includes a fixed housing 12 that
is constructed from numerous pieces secured to one another. A
compressor section 14 having compressor hubs 16 with blades are
driven by a turbine shaft 25 about an axis A. A turbo fan 18 is
supported on a turbo fan shaft 20 that is driven by a compressor
shaft 24, which supports the compressor hubs 16, through an
epicyclic gear train 22.
[0033] In the example arrangement shown, the epicyclic gear train
22 is a star gear train. Referring to FIG. 2, the epicyclic gear
train 22 includes a sun gear 30 that is connected to the compressor
shaft 24, which provides rotational input, by a splined connection.
A carrier 26 is fixed to the housing 12 by a torque frame 28 using
fingers (not shown) known in the art. The carrier 26 supports star
gears 32 using journal bearings 34 that are coupled to the sun gear
30 by meshed interfaces between the teeth of sun and star gears 30,
32. Multiple star gears 32 are arranged circumferentially about the
sun gear 30. Retainers 36 retain the journal bearings 34 to the
carrier 26. A ring gear 38 surrounds the carrier 26 and is coupled
to the star gears 32 by meshed interfaces. The ring gear 38, which
provides rotational output, is secured to the turbo fan shaft 20 by
circumferentially arranged fastening elements, which are described
in more detail below.
[0034] FIG. 2B is an expanded view of a portion of FIG. 2A. As
shown in FIG. 2B, a gearbox assembly 90, which is shown as an
epicyclic gear arrangement, is arranged about a central axis 90a.
The gearbox assembly 90 is supported in part by a forward, first
bearing 96 and a rear, second bearing 98 that is spaced apart from
the forward bearing 96. The forward bearing 96 and the rear bearing
98 are mounted on a support arm 92. The support arm 92 extends
axially forwardly from the gearbox assembly 90 and is connected at
one end 92a at a radially outer location of the gearbox assembly
90.
[0035] In the example, the forward bearing 96 and the rear bearing
98 are located axially forward of the gearbox assembly 90 and are
spaced an equivalent radial distance along line G from the central
axis 90a. That is, the bearings 96 and 98 are generally axially
aligned. In the illustrated example, the forward bearing 96 is
located at an equivalent axial position of the fan 20, as
represented by the radial line R1, and the rear bearing 98 is
located at a non-equivalent axial position of the fan 20, as
represented by the radial line R2.
[0036] As further shown in FIG. 2B, the forward bearing 96 and the
rear bearing 98 are tapered bearings. In the example, the forward
bearing 96 includes a first cylindrical roller element 96a that is
supported between a tapered inner race 96b and a tapered outer race
96c. The rear bearing 98 includes a second cylindrical roller
element 98a that is supported between a tapered inner race 98b and
a tapered outer race 98c. The first cylindrical roller element 96a
defines a first rotational axis 96d and the second cylindrical
roller element 98a defines a second rotational axis 98d. As shown,
the rotational axes 96d and 98d intersect at a position that is
radially inwards from the first cylindrical roller element 96a and
the second cylindrical roller element 98a. Thus, the intersection
point is radially inwards of line G. As also shown, the point of
intersection is also radially inwards of a radially outer surface
90b of the gearbox assembly 90 and radially outwards of a radially
inner surface 90c of the gearbox assembly 90.
[0037] Referring to FIGS. 3 and 4, the ring gear 38 is a two-piece
construction having first and second portions 40, 42. The first and
second portions 40, 42 abut one another at a radial interface 45. A
trough 41 separates oppositely angled teeth 43 (best shown in FIG.
4) on each of the first and second portions 40, 42. The arrangement
of teeth 43 forces the first and second portions 40, 42 toward one
another at the radial interface 45. The back side of the first and
second portions 40, 42 includes a generally S-shaped outer
circumferential surface 47 that, coupled with a change in
thickness, provides structural rigidity and resistance to
overturning moments. The first and second portions 40, 42 have a
first thickness T1 that is less than a second thickness T2 arranged
axially inwardly from the first thickness T1. The first and second
portions 40, 42 include facing recesses 44 that form an internal
annular cavity 46.
[0038] The first and second portions 40, 42 include flanges 51 that
extend radially outward away from the teeth 43. The turbo fan shaft
20 includes a radially outwardly extending flange 70 that is
secured to the flanges 51 by circumferentially arranged bolts 52
and nuts 54, which axially constrain and affix the turbo fan shaft
20 and ring gear 38 relative to one another. Thus, the spline ring
is eliminated, which also reduces heat generated from windage and
churning that resulted from the sharp edges and surface area of the
splines. The turbo fan shaft 20 and ring gear 38 can be
rotationally balanced with one another since radial movement
resulting from the use of splines is eliminated. An oil baffle 68
is also secured to the flanges 51, 70 and balanced with the
assembly.
[0039] Seals 56 having knife edges 58 are secured to the flanges
51, 70. The first and second portions 40, 42 have grooves 48 at the
radial interface 45 that form a hole 50, which expels oil through
the ring gear 38 to a gutter 60 that is secured to the carrier 26
with fasteners 61 (FIG. 2). The direct radial flow path provided by
the grooves 48 reduces windage and churning by avoiding the axial
flow path change that existed with splines. That is, the oil had to
flow radially and then axially to exit through the spline
interface. The gutter 60 is constructed from a soft material such
as aluminum so that the knife edges 58, which are constructed from
steel, can cut into the aluminum if they interfere. Referring to
FIG. 3, the seals 56 also include oil return passages 62 provided
by first and second slots 64 in the seals 56, which permit oil on
either side of the ring gear 38 to drain into the gutter 60. In the
example shown in FIG. 2, the first and second slots 64, 66 are
instead provided in the flange 70 and oil baffle 68,
respectively.
[0040] Although a preferred embodiment of this invention has been
disclosed, a worker of ordinary skill in this art would recognize
that certain modifications would come within the scope of this
invention. For that reason, the following claims should be studied
to determine the true scope and content of this invention.
* * * * *