U.S. patent application number 15/112869 was filed with the patent office on 2018-06-14 for auxiliary oil system for geared gas turbine engine.
This patent application is currently assigned to UNITED TECHNOLOGIES CORPORATION. The applicant listed for this patent is UNITED TECHNOLOGIES CORPORATION. Invention is credited to William G. Sheridan.
Application Number | 20180163625 15/112869 |
Document ID | / |
Family ID | 57234803 |
Filed Date | 2018-06-14 |
United States Patent
Application |
20180163625 |
Kind Code |
A9 |
Sheridan; William G. |
June 14, 2018 |
AUXILIARY OIL SYSTEM FOR GEARED GAS TURBINE ENGINE
Abstract
A gas turbine engine comprises a fan drive turbine, a fan rotor,
and a gear reduction driven by the fan drive turbine to, in turn,
drive the gear architecture. A main oil supply system supplies oil
to components within the gear reduction, and an auxiliary oil
supply system. The auxiliary oil system operates to ensure that the
gear reduction will be adequately supplied with lubricant for at
least 30 seconds at power should the main oil supply system
fail.
Inventors: |
Sheridan; William G.;
(Southington, CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
UNITED TECHNOLOGIES CORPORATION |
Farmington |
CT |
US |
|
|
Assignee: |
UNITED TECHNOLOGIES
CORPORATION
Farmington
CT
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20170002738 A1 |
January 5, 2017 |
|
|
Family ID: |
57234803 |
Appl. No.: |
15/112869 |
Filed: |
January 2, 2015 |
PCT Filed: |
January 2, 2015 |
PCT NO: |
PCT/US15/10020 PCKC 00 |
371 Date: |
July 20, 2016 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61929150 |
Jan 20, 2014 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F05D 2260/84 20130101;
F05D 2270/09 20130101; F05D 2260/98 20130101; F05D 2220/323
20130101; F02K 3/06 20130101; F05D 2260/40311 20130101; F01D 25/20
20130101; F02C 7/06 20130101; F16H 57/08 20130101; F16H 57/04
20130101 |
International
Class: |
F02C 7/06 20060101
F02C007/06; F02K 3/06 20060101 F02K003/06; F01D 25/20 20060101
F01D025/20 |
Claims
1. A gas turbine engine comprising: a fan drive turbine, a fan
rotor, and a gear reduction driven by said fan drive turbine to, in
turn, drive said gear architecture, a main oil supply system for
supplying oil to components within said gear reduction, and an
auxiliary oil supply system; and said auxiliary oil system being
operable to ensure that the gear reduction will be adequately
supplied with lubricant for at least 30 seconds at power should the
main oil supply system fail.
2. The gas turbine engine as set forth in claim 1, wherein said
gear reduction includes a sun gear being driven by said fan drive
turbine to drive intermediate gears that engage a ring gear.
3. The gas turbine engine as set forth in claim 2, wherein said sun
gear, said intermediate gears and said ring gear are enclosed in a
bearing compartment, which captures oil removed via a scavenge line
connected to a main oil pump.
4. The gas turbine engine as set forth in claim 3, wherein said
main oil pump has a gutter that directs scavenged oil to a main oil
tank.
5. The gas turbine engine as set forth in claim 4, wherein oil in
said main oil tank feeds a main pump pressure stage which then
delivers oil to said gear reduction.
6. The gas turbine engine as set forth in claim 5, wherein oil from
said main pump pressure stage passes through a lubrication system
that includes at least one filter and at least one heat exchanger
to cool the oil.
7. The gas turbine engine as set forth in claim 4, wherein said
gear reduction is surrounded by an oil gutter that scavenges oil
and directs it to an auxiliary oil tank.
8. The gas turbine engine as set forth in claim 7, wherein said
auxiliary oil tank has an overflow conduit that allows excess oil
to fall to the bottom of said bearing compartment.
9. The gas turbine engine as set forth in claim 8, wherein said
auxiliary oil tank has a tube with holes at a vertically higher
location thereon, such that oil is drawn from said auxiliary oil
tank when it is full or under negative gravity conditions.
10. The gas turbine engine as set forth in claim 7, wherein said
gutter is at least 70% efficient, defined as the volume of oil
captured in said gutter being directed to said auxiliary oil tank
compared to a volume of oil that falls out of said gutter and is
scavenged by said main scavenge pump.
11. The gas turbine engine as set forth in claim 7, wherein said
auxiliary oil supply system includes an auxiliary pump.
12. The gas turbine engine as set forth in claim 11, wherein said
gear reduction drives auxiliary gears which, in turn, drive said
auxiliary pump, such that whenever said gear reduction is turning,
it drives said auxiliary pump.
13. The gas turbine engine as set forth in claim 11, wherein said
auxiliary pump draws oil from the bottom of an oil sump and said
bottom of said oil sump is at lower elevation than a line leading
from said oil sump to said main pump scavenge stage.
14. The gas turbine engine as set forth in claim 13, wherein said
auxiliary pump also draws oil from said auxiliary oil tank.
15. The gas turbine engine as set forth in claim 13, wherein said
oil sump traps residual oil in said bearing compartment, such that
oil is supplied to said auxiliary pump under negative gravity
conditions as well as positive gravity conditions.
16. The gas turbine engine as set forth in claim 15, wherein said
auxiliary oil tank has a tube with holes at a vertically higher
location thereon, such that oil is drawn from said auxiliary oil
tank when it is full or under negative gravity conditions.
17. The gas turbine engine as set forth in claim 16, wherein oil is
also drawn from said auxiliary tank when said tank is full and
through overflow through said overflow conduit.
18. The gas turbine engine as set forth in claim 11, wherein said
auxiliary pump supplies oil to a conduit and then to a valve, and
said valve sensing pressure in a line associated with said main
lubricant supply.
19. The gas turbine engine as set forth in claim 18, wherein if
said sensed pressure is adequate, oil is supplied from said
auxiliary pump back into said main oil tank.
20. The gas turbine engine as set forth in claim 19, wherein if the
oil pressure associated with said main oil supply system is below
an adequate pressure, oil is sent from said auxiliary pump to said
gear reduction.
21. The gas turbine engine as set forth in claim 1, wherein said
auxiliary oil system being operable to allow the engine to operate
under windmill conditions in the air for up to 90 minutes.
22. The gas turbine engine as set forth in claim 21, wherein said
auxiliary oil system being operable to operate indefinitely on the
ground when windmilling with wind speeds below 85 mph or less.
23. The gas turbine engine as set forth in claim 22, wherein said
auxiliary oil system being operable to fly with the engine in an
aircraft under negative gravity conditions for at least 20
seconds.
24. The gas turbine engine as set forth in claim 21, wherein said
auxiliary oil system being operable to fly with the engine in an
aircraft under negative gravity conditions for at least 20
seconds.
25. The gas turbine engine as set forth in claim 1, wherein said
auxiliary oil system being operable to operate indefinitely on the
ground when windmilling with wind speeds below 85 mph or less.
26. The gas turbine engine as set forth in claim 1, wherein said
auxiliary oil system being operable to fly with the engine in an
aircraft under negative gravity conditions for at least 20 seconds.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to U.S. Provisional Patent
Application No. 61/929,150, filed Jan. 20, 2014.
BACKGROUND OF THE INVENTION
[0002] This application relates to an auxiliary oil system to
supplement a main oil supply system on a gas turbine engine with a
gear drive for a fan.
[0003] Gas turbine engines are known and, typically, include a fan
delivering air into a bypass duct as propulsion air and also
delivering air into a core engine. The core engine flow passes into
a compressor where it is compressed and then delivered into a
combustion section. The compressed air is mixed with fuel and
ignited in the combustion section and products of this combustion
pass downstream over turbine rotors driving them to rotate.
[0004] Historically, a turbine rotor drove the fan rotor at a
single speed. This led to compromise in the desired speed for both
the fan rotor and the turbine rotor. The fan rotor could not rotate
unduly fast and, thus, the turbine rotor typically rotated slower
than would be desired.
[0005] More recently, it has been proposed to include a gear
reduction between a fan drive turbine and the fan rotor. This has
allowed the fan to rotate at slower speeds and results in many
efficiencies.
[0006] However, the gear reduction requires adequate lubrication
and must be lubricated even under extreme flight conditions.
SUMMARY OF THE INVENTION
[0007] In a featured embodiment, a gas turbine engine comprises a
fan drive turbine, a fan rotor, and a gear reduction driven by the
fan drive turbine to, in turn, drive the gear architecture. A main
oil supply system supplies oil to components within the gear
reduction, and an auxiliary oil supply system. The auxiliary oil
system operates to ensure that the gear reduction will be
adequately supplied with lubricant for at least 30 seconds at power
should the main oil supply system fail.
[0008] In another embodiment according to the previous embodiment,
the gear reduction includes a sun gear driven by the fan drive
turbine to drive intermediate gears that engage a ring gear.
[0009] In another embodiment according to any of the previous
embodiments, the sun gear, the intermediate gears and the ring gear
are enclosed in a bearing compartment, which captures oil removed
via a scavenge line connected to a main oil pump.
[0010] In another embodiment according to any of the previous
embodiments, the main oil pump has a gutter that directs scavenged
oil to a main oil tank.
[0011] In another embodiment according to any of the previous
embodiments, oil in the main oil tank feeds a main pump pressure
stage which then delivers oil to the gear reduction.
[0012] In another embodiment according to any of the previous
embodiments, oil from the main pump pressure stage passes through a
lubrication system that includes at least one filter and at least
one heat exchanger to cool the oil.
[0013] In another embodiment according to any of the previous
embodiments, the gear reduction is surrounded by an oil gutter that
scavenges oil and directs it to an auxiliary oil tank.
[0014] In another embodiment according to any of the previous
embodiments, the auxiliary oil tank has an overflow conduit that
allows excess oil to fall to the bottom of the bearing
compartment.
[0015] In another embodiment according to any of the previous
embodiments, the auxiliary oil tank has a tube with holes at a
vertically higher location thereon, such that oil is drawn from the
auxiliary oil tank when it is full or under negative gravity
conditions.
[0016] In another embodiment according to any of the previous
embodiments, the gutter is at least 70% efficient, defined as the
volume of oil captured in the gutter directed to the auxiliary oil
tank compared to a volume of oil that falls out of the gutter and
is scavenged by the main scavenge pump.
[0017] In another embodiment according to any of the previous
embodiments, the auxiliary oil supply system includes an auxiliary
pump.
[0018] In another embodiment according to any of the previous
embodiments, the gear reduction drives auxiliary gears which, in
turn, drive the auxiliary pump, such that whenever the gear
reduction is turning, it drives the auxiliary pump.
[0019] In another embodiment according to any of the previous
embodiments, the auxiliary pump draws oil from the bottom of an oil
sump and the bottom of the oil sump is at lower elevation than a
line leading from the oil sump to the main pump scavenge stage.
[0020] In another embodiment according to any of the previous
embodiments, the auxiliary pump also draws oil from the auxiliary
oil tank.
[0021] In another embodiment according to any of the previous
embodiments, the oil sump traps residual oil in the bearing
compartment, such that oil is supplied to the auxiliary pump under
negative gravity conditions as well as positive gravity
conditions.
[0022] These and other features may be best understood from the
following drawings and specification.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 shows a schematic of a gas turbine engine.
[0024] FIG. 2 is a schematic of an oil supply system.
DETAILED DESCRIPTION
[0025] FIG. 1 schematically illustrates a gas turbine engine 20.
The gas turbine engine 20 is disclosed herein as a two-spool
turbofan that generally incorporates a fan section 22, a compressor
section 24, a combustor section 26 and a turbine section 28.
Alternative engines might include an augmentor section (not shown)
among other systems or features. The fan section 22 drives air
along a bypass flow path B in a bypass duct defined within a
nacelle 15, while the compressor section 24 drives air along a core
flow path C for compression and communication into the combustor
section 26 then expansion through the turbine section 28. Although
depicted as a two-spool turbofan gas turbine engine in the
disclosed non-limiting embodiment, it should be understood that the
concepts described herein are not limited to use with two-spool
turbofans as the teachings may be applied to other types of turbine
engines including three-spool architectures.
[0026] The exemplary engine 20 generally includes a low speed spool
30 and a high speed spool 32 mounted for rotation about an engine
central longitudinal axis A relative to an engine static structure
36 via several bearing systems 38. It should be understood that
various bearing systems 38 at various locations may alternatively
or additionally be provided, and the location of bearing systems 38
may be varied as appropriate to the application.
[0027] The low speed spool 30 generally includes an inner shaft 40
that interconnects a fan 42, a first (or low) pressure compressor
44 and a first (or low) pressure turbine 46. The inner shaft 40 is
connected to the fan 42 through a speed change mechanism, which in
exemplary gas turbine engine 20 is illustrated as a geared
architecture 48 to drive the fan 42 at a lower speed than the low
speed spool 30. The high speed spool 32 includes an outer shaft 50
that interconnects a second (or high) pressure compressor 52 and a
second (or high) pressure turbine 54. A combustor 56 is arranged in
exemplary gas turbine 20 between the high pressure compressor 52
and the high pressure turbine 54. A mid-turbine frame 57 of the
engine static structure 36 is arranged generally between the high
pressure turbine 54 and the low pressure turbine 46. The
mid-turbine frame 57 further supports bearing systems 38 in the
turbine section 28. The inner shaft 40 and the outer shaft 50 are
concentric and rotate via bearing systems 38 about the engine
central longitudinal axis A which is collinear with their
longitudinal axes.
[0028] The core airflow is compressed by the low pressure
compressor 44 then the high pressure compressor 52, mixed and
burned with fuel in the combustor 56, then expanded over the high
pressure turbine 54 and low pressure turbine 46. The mid-turbine
frame 57 includes airfoils 59 which are in the core airflow path C.
The turbines 46, 54 rotationally drive the respective low speed
spool 30 and high speed spool 32 in response to the expansion. It
will be appreciated that each of the positions of the fan section
22, compressor section 24, combustor section 26, turbine section
28, and fan drive gear system 48 may be varied. For example, gear
system 48 may be located aft of combustor section 26 or even aft of
turbine section 28, and fan section 22 may be positioned forward or
aft of the location of gear system 48.
[0029] The engine 20 in one example is a high-bypass geared
aircraft engine. In a further example, the engine 20 bypass ratio
is greater than about six (6), with an example embodiment being
greater than about ten (10), the geared architecture 48 is an
epicyclic gear train, such as a planetary gear system or other gear
system, with a gear reduction ratio of greater than about 2.3 and
the low pressure turbine 46 has a pressure ratio that is greater
than about five. In one disclosed embodiment, the engine 20 bypass
ratio is greater than about ten (10:1), the fan diameter is
significantly larger than that of the low pressure compressor 44,
and the low pressure turbine 46 has a pressure ratio that is
greater than about five 5:1. Low pressure turbine 46 pressure ratio
is pressure measured prior to inlet of low pressure turbine 46 as
related to the pressure at the outlet of the low pressure turbine
46 prior to an exhaust nozzle. The geared architecture 48 may be an
epicycle gear train, such as a planetary gear system or other gear
system, with a gear reduction ratio of greater than about 2.3:1. It
should be understood, however, that the above parameters are only
exemplary of one embodiment of a geared architecture engine and
that the present invention is applicable to other gas turbine
engines including direct drive turbofans.
[0030] A significant amount of thrust is provided by the bypass
flow B due to the high bypass ratio. The fan section 22 of the
engine 20 is designed for a particular flight condition--typically
cruise at about 0.8 Mach and about 35,000 feet. The flight
condition of 0.8 Mach and 35,000 ft, with the engine at its best
fuel consumption--also known as "bucket cruise Thrust Specific Fuel
Consumption (`TSFC`)"--is the industry standard parameter of lbm of
fuel being burned divided by lbf of thrust the engine produces at
that minimum point. "Low fan pressure ratio" is the pressure ratio
across the fan blade alone, without a Fan Exit Guide Vane ("FEGV")
system. The low fan pressure ratio as disclosed herein according to
one non-limiting embodiment is less than about 1.45. "Low corrected
fan tip speed" is the actual fan tip speed in ft/sec divided by an
industry standard temperature correction of [(Tram .degree.
R)/(518.7.degree. R)].sup.0.5. The "Low corrected fan tip speed" as
disclosed herein according to one non-limiting embodiment is less
than about 1150 ft/second.
[0031] FIG. 2 shows an oil supply system 99 for the gear reduction
such as gear reduction 48 in the gas turbine engine 20 of FIG. 1.
The gear reduction 48 includes a sun gear 100 which is driven by a
fan drive turbine (such as turbine 46 of FIG. 1) and engages a
plurality of intermediate gears 102. In some embodiments, the
intermediate gears 102 may be planet gears of a planetary epicyclic
gear system. In other embodiments, the intermediate gears 102 may
be star gears of a star epicyclic gear system. In some embodiments,
the intermediate gears 102, in turn, drive a ring gear 103 which
drives a fan drive shaft to, in turn, rotate a fan (such as fan
rotor 42). Other planetary gear arrangements would come within the
scope of this application and the above is merely one example for a
gear reduction which may be utilized to drive a fan rotor. For
example, in other embodiments, a planetary gear carrier (not shown)
driven by planetary gears may drive the fan shaft.
[0032] Oil supply 104 is shown schematically delivering oil to the
planet gears 102. It should be understood the oil is supplied to
other components such as journal pins, bearings, etc. associated
with the gear architecture illustrated in FIG. 2.
[0033] Oil is supplied from a line 106 delivered from a main oil
supply pump 108. A pressure stage of the main oil supply pump 108
receives oil from an oil tank 142. The oil in the oil tank 142
feeds the main pump 108 and is then conditioned in a lubrication
system 110 that may contain filters to clean the oil and heat
exchangers to cool the oil, as known. The oil then passes back to
the gear architecture 48 through the line 106.
[0034] A bearing compartment 112 surrounds the gear reduction 48.
The bearing compartment 112 has oil removed via a scavenge line
180, which returns the oil to a scavenge side 109 of the main pump
108, which, in turn, delivers the oil back to the oil tank 142.
[0035] The gear architecture is surrounded by an oil gutter 114,
shown schematically, that scavenges oil from the gear architecture
and directs it to an auxiliary tank 116. When tank 116 is full, an
overflow conduit 117 allows excess oil to fall to the bottom of the
bearing compartment 112. The gutter 114 is at least 70% efficient.
This means that up to 30% of the oil falls out of the gutter and is
scavenged by the main scavenge pump 109 through line 180. The 70%
that is captured in the gutter is directed into the tank 116.
[0036] The detail of the oil supply 104, the gutter 114 and the
gears generally may be as shown in U.S. Patent Application
2008/0116010, now U.S. Pat. No. 8,215,454, issued Jul. 10, 2012.
The details of those features are incorporated herein by reference.
The gear system and, in particular, the intermediate gears 102
drive auxiliary gears 190 and 191 which are shown schematically
driving an auxiliary pump 124. Thus, as long as the gears 102 or
103 are being rotated, the gears 190 and 191 will drive the
auxiliary pump 124.
[0037] The pump 124 draws oil from a sump 126 at a bottom of the
compartment 112 through a line 128. The sump 126 is at a lower
elevation than the main scavenge line 180 and also draws oil from
the tank 116 through the line 122. Sump 126 will trap any residual
oil in the bearing compartment 112.
[0038] There are challenges with the auxiliary pump with regard to
negative gravity conditions. Further, if there is a break in the
main oil supply system or windmilling of the engine when the engine
is otherwise shut down, it is desirable for the engine to be able
to maintain operation for at least 30 seconds at power without
damage if the main oil line (108/106, etc.) ruptures. This will
provide a pilot time to shut the engine down.
[0039] It is also desirable to allow the engine to windmill in the
air for up to 90 minutes without damage if it is shut down for
other reasons than oil system failure. It is also desirable to
allow the engine to windmill indefinitely on the ground with wind
speeds below 85 mph or less. As known, windmilling refers to a
condition where the engine is shut down, however, air being forced
into the fan rotates the fan, in turn, causing components to
rotate.
[0040] Finally, it is desirable to allow an aircraft to fly under
negative gravity conditions for at least 20 seconds.
[0041] All of these raise challenges with regard to operating the
engine and supplying oil to the gear components.
[0042] The arrangement of the components, as described above, allow
these conditions to be met.
[0043] The auxiliary pump 124 draws oil from the sump 126. Pump 124
also draws oil from a line 122. The tank 116 has a tube 118 with
holes 120 at a vertically higher location, such that oil is only
drawn from the tank 116 to the line 122 when it is full or under
negative gravity conditions. Otherwise, oil is drained from the
tank 116 by overflow through the conduit 117.
[0044] The auxiliary pump 124 supplies oil to the conduit 130 and
then to a valve 132. Valve 132 senses a pressure (through line 140)
in the main line 144. If the pressure is acceptable, oil from the
line 130 is sent by the valve 132 back to the tank 142 through a
line 199. Thus, if the pressure is acceptable, the oil is recycled
for reuse during normal operation. On the other hand, if the
pressure on the main line 144 is low, oil is sent into a conduit
200 and then passes into the conduit 106 to bypass the main
lubrication system and feed the gear reduction 48 to ensure that
the conditions as described above are met.
[0045] The conditions as described above are met in large part,
since the auxiliary oil tank 116, and the tube 118, has the holes
120 only at the top, such that oil is only drawn from the tank 116,
through the line 122 when it is full, or under negative G
conditions. Further, since the sump 126 is at a lower elevation
than a main scavenge line 180, the auxiliary pump 124 will always
be supplied with oil, in both positive and negative G conditions.
Further, the auxiliary pump 124, in combination with the valve 132,
ensure that oil will be supplied in adequate amounts during the
conditions set forth above.
[0046] Although an 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.
* * * * *