U.S. patent application number 09/845447 was filed with the patent office on 2002-11-14 for methods and systems for preventing gas turbine engine lube oil leakage.
Invention is credited to Granitz, Charles Robert, Haaser, Frederic Gardner, Khera, Awtar Singh, Przytulski, James Charles.
Application Number | 20020166317 09/845447 |
Document ID | / |
Family ID | 25295252 |
Filed Date | 2002-11-14 |
United States Patent
Application |
20020166317 |
Kind Code |
A1 |
Przytulski, James Charles ;
et al. |
November 14, 2002 |
METHODS AND SYSTEMS FOR PREVENTING GAS TURBINE ENGINE LUBE OIL
LEAKAGE
Abstract
A sump evacuation system for a gas turbine facilitates reducing
oil leakage from bearing assembly sumps in a cost-effective and
reliable manner. The engine includes at least one bearing assembly
housed within a sump pressurization cavity. The sump evacuation
system includes a sump pressurization cavity, a sump oil cavity, an
air/oil separator, and an air pump. The bearing assembly and the
sump oil cavity are coupled in flow communication with the sump
pressurization cavity, and the air/oil separator is coupled in flow
communication with the sump oil cavity. Furthermore, the air pump
is coupled in flow communication with the air/oil separator.
Inventors: |
Przytulski, James Charles;
(Fairfield, OH) ; Granitz, Charles Robert;
(Cincinnati, OH) ; Haaser, Frederic Gardner;
(Cincinnati, OH) ; Khera, Awtar Singh; (West
Chester, OH) |
Correspondence
Address: |
GENERAL ELECTRIC COMPANY
ANDREW C HESS
GE AIRCRAFT ENGINES
ONE NEUMANN WAY M/D H17
CINCINNATI
OH
452156301
|
Family ID: |
25295252 |
Appl. No.: |
09/845447 |
Filed: |
April 30, 2001 |
Current U.S.
Class: |
60/39.08 |
Current CPC
Class: |
F01D 25/125 20130101;
F01D 25/183 20130101; F05D 2260/6022 20130101; F01D 25/20 20130101;
F02C 7/06 20130101 |
Class at
Publication: |
60/39.08 |
International
Class: |
F02G 003/00; F02C
007/06 |
Claims
What is claimed is:
1. A method for operating a gas turbine engine to facilitate
reducing engine lubrication system leakage, the engine including at
least one bearing assembly and a sump evacuation system including a
sump oil cavity, a sump pressurization cavity, and an air pump, the
bearing assembly within the sump pressurization cavity, the air
pump in flow communication with the sump oil cavity, said method
comprising the steps of: supplying sump pressurization air to the
sump pressurization cavity; venting the sump oil cavity; and
reducing the operating pressure of the sump oil cavity in
comparison to the operating pressure of the sump pressurization
cavity.
2. A method in accordance with claim 1 wherein said step of
reducing the operating pressure of the sump oil cavity further
comprises operating the air pump to reduce the operating pressure
of the sump oil cavity relative to the sump pressurization
cavity.
3. A method in accordance with claim 1 wherein the sump evacuation
system includes an air/oil separator, said step of reducing the
operating pressure of the sump oil cavity further comprises the
steps of: coupling the air pump downstream from the air/oil
separator; and operating the air pump to reduce the operating
pressure of the sump oil cavity relative to the sump pressurization
cavity.
4. A method in accordance with claim 3 wherein said step operating
the air pump further comprises the step of operating the air pump
during engine low-power and idle operations to reduce the operating
pressure of the sump oil cavity relative to the sump pressurization
cavity.
5. A method in accordance with claim 3 wherein the engine includes
an accessory gear box, said step of operating the air pump further
comprises the step of coupling the air pump to the engine accessory
gear box.
6. A sump evacuation system for a gas turbine engine, said sump
evacuation system comprising: a sump pressurization cavity; a sump
oil cavity in flow communication with said sump pressurization
cavity; and an air pump in flow communication with said sump oil
cavity, said air pump configured to induce a vacuum within said
sump oil cavity relative to said sump pressurization cavity.
7. A sump evacuation system in accordance with claim 6 further
comprising an said air/oil separator coupled to an engine accessory
gear box, such that said air/oil separator in flow communication
with said air pump.
8. A sump evacuation system in accordance with claim 6 wherein said
sump oil cavity within said sump pressurization cavity.
9. A sump evacuation system in accordance with claim 6 wherein said
air pump down stream from said sump oil cavity.
10. A sump evacuation system in accordance with claim 6 further
comprising an air/oil separator in flow communication with said air
pump, said air pump downstream from said air/oil separator, said
air/oil separator downstream from said sump oil cavity.
11. A sump evacuation system in accordance with claim 6 wherein
said air pump configured to operate during engine idle and
low-power operations.
12. A sump evacuation system in accordance with claim 6 wherein the
engine includes an exhaust system, said air pump in flow
communication with the engine exhaust system.
13. A gas turbine engine comprising: at least one bearing assembly;
and a sump evacuation system configured to supply lubrication to
said bearing assembly, said sump evacuation system comprising a
sump pressurization cavity, a sump oil cavity, and an air pump,
said bearing assembly and said sump oil cavity in flow
communication with said sump pressurization cavity, said air/oil
separator in flow communication with said sump oil cavity, said air
pump configured to reduce an operating pressure of said sump oil
cavity relative to said to said sump pressurization cavity.
14. A gas turbine engine in accordance with claim 13 wherein said
sump evacuation system air pump downstream from said sump oil
cavity.
15. A gas turbine engine in accordance with claim 14 wherein said
sump evacuation system further comprises an air/oil separator
coupled upstream from said sump evacuation system air pump.
16. A gas turbine engine in accordance with claim 14 further
comprising an engine accessory gear box, said sump evacuation
system air/oil separator coupled to said engine accessory gear
box.
17. A gas turbine engine in accordance with claim 14 further
comprising an engine exhaust system, said sump evacuation system
air pump in flow communication with said engine exhaust system.
18. A gas turbine engine in accordance with claim 14 wherein said
sump evacuation system air pump configured to operate during engine
idle and low-power operations.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates generally to gas turbine engines, and
more specifically to sump evacuation systems used with gas turbine
engine engines.
[0002] A gas turbine engine typically includes at least one bearing
assembly that rotatably supports a shaft. The bearing assembly is
lubricated with oil, and heat from other engine components is
absorbed and dissipated by the same oil. Accordingly, bearing
assemblies are housed within sumps that include a supply pump that
supplies lubricating oil under pressure to the bearing assemblies,
and a scavenge pump that removes lubricating oil from the sump. The
scavenge pump causes the return oil to pass through a heat
exchanger prior to returning the oil to a tank or reservoir. The
bearing assembly sumps also include seal assemblies that facilitate
minimizing oil leakage from the sumps along the rotor shaft.
[0003] To further facilitate reducing oil from leaking from the
bearing assembly sumps, at least some known bearing assembly sumps
are also housed within pressurized cavities. The cavities include
seal labyrinths that extend around the rotor shaft. During
operation, compressed air is supplied to each surrounding
pressurized cavity to maintain a positive pressure around the
bearing assembly sump. Thus, oil leakage from the bearing assembly
sump having the lower operating pressure to the pressurized cavity
having the higher operating pressure is facilitated to be
reduced.
[0004] However, during some engine operating conditions, the
pressurization of the air supplied to the pressurized cavity may be
insufficient to prevent the oil from leaking from the bearing
assembly sump or seals. Moreover, because such leakage may be
excessive, identifying a source of such leakage, and repairing the
engine to prevent future leakage, may be a time-consuming and
costly process.
BRIEF SUMMARY OF THE INVENTION
[0005] In an exemplary embodiment, a sump evacuation system for a
gas turbine facilitates reducing oil leakage from bearing assembly
sumps in a cost-effective and reliable manner. The engine includes
at least one bearing assembly. The sump evacuation system includes
a sump pressurization cavity, a sump oil cavity, and an air pump.
The bearing assembly is housed within the sump oil cavity and is
coupled in flow communication with the sump pressurization cavity.
The air pump is coupled in flow communication with the sump oil
cavity.
[0006] During low-power or idle engine operations, the sump
evacuation system is activated to facilitate preventing oil from
inadvertently leaking from the sump oil cavity. More specifically,
the sump evacuation system air pump draws air from the sump oil
cavity, such that an operating pressure within the sump oil cavity
is reduced below that of an operating pressure within the sump
pressurization cavity. As a result, the oil is prevented from
leaking from the lower pressure sump oil cavity during low-power or
idle engine operations in a cost-effective and reliable manner.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is schematic illustration of a gas turbine engine
including an engine lubrication system;
[0008] FIG. 2 is a schematic illustration of a known lubrication
system that may be used with the gas turbine engine shown in FIG.
1; and
[0009] FIG. 3 is a schematic illustration of a sump evacuation
system used with the lubrication system shown in FIG. 2.
DETAILED DESCRIPTION OF THE INVENTION
[0010] FIG. 1 is a schematic illustration of a gas turbine engine
10 including a low pressure compressor 12, a high pressure
compressor 14, and a combustor 16. Engine 10 also includes a high
pressure turbine 18 and a low pressure turbine 20. Compressor 12
and turbine 20 are coupled by a first shaft 22, and compressor 14
and turbine 18 are coupled by a second shaft 24. In one embodiment,
engine 10 is an LM2500 or LM2500+ engine commercially available
from General Electric Company, Cincinnati, Ohio.
[0011] Engine 10 also includes a plurality of bearing assemblies 26
that rotatably support shafts 22 and 24. Each bearing assembly 26
is coupled in flow communication to a lubrication system 28 that
supplies oil to each bearing assembly 26 for cooling and
lubricating each bearing assembly 26. Lubrication system 28 is
known in the art and includes supply and scavenge pump assembly 30
that is driven by an accessory drive or gear box 32, as is known in
the art. More specifically, a supply portion (not shown in FIG. 1)
of assembly 30 provides oil from a supply source (not shown) under
pressure to sumps (not shown in FIG. 1) of bearing assemblies 26 to
cool and lubricate each bearing (not shown in FIG. 1). A scavenge
portion (not shown in FIG. 1) of assembly 30 withdraws lubricating
oil from the bearing assembly sumps and returns the oil to the
supply source via a heat exchange device (not shown).
[0012] During engine operation, air flows through low pressure
compressor 12 and compressed air is supplied from low pressure
compressor 12 to high pressure compressor 14. The highly compressed
air is delivered to combustor 16. Airflow (not shown in FIG. 1)
from combustor 16 drives turbines 18 and 20 and exits gas turbine
engine 10 through a nozzle 36.
[0013] FIG. 2 is a schematic illustration of lubrication system 28,
including a bearing assembly 40 that rotatably supports a rotor
shaft 42. In one embodiment, rotor shaft 42 is similar to rotor
shaft 22 shown in FIG. 1. In another embodiment, rotor shaft 42 is
similar to rotor shaft 24 shown in FIG. 1. Bearing assembly 40 is
housed within a sump oil cavity 44, and is in flow communication
with lubrication system supply and scavenge portions 46 and 48,
respectively. More specifically, lubrication system supply portion
46 provides oil from a supply source (not shown) under pressure to
sump oil cavity 44 to cool and lubricate each bearing assembly
bearing 50. Furthermore, lubrication system scavenge portion 48
withdraws lubricating oil from sump oil cavity 44 and returns the
oil to the supply source.
[0014] In the exemplary embodiment, sump oil cavity 44 includes a
plurality of seal assemblies 60 to facilitate oil supplied under
pressure from lubrication system supply portion 46 from
inadvertently leaking from cavity 44 along shaft 42. Each seal
assembly 60 includes an air seal portion 62 and an oil seal portion
64. Oil seal portion 64 is coupled within each seal assembly 60
with a plurality windback threads 65. Furthermore, each oil seal
portion 64 includes an oil slinger 66, such that oil entering each
seal assembly 60 along rotor shaft 42 is returned into sump oil
cavity 44 when shaft 42 is rotating. Sump oil cavity 44 also
includes a sump vent 70 that is coupled to a sump evacuation system
(not shown in FIG. 2).
[0015] Sump oil cavity 44 is encased within a sump pressurization
cavity 80. Sump pressurization cavity 80 is in flow communication
with an air source and receives compressed air 82 for pressurizing
sump pressurization cavity 80. In one embodiment, compressed air 82
is supplied from high pressure compressor 14. Sump pressurization
cavity 80 includes a plurality of air seal assemblies 86 to
facilitate compressed air 82 supplied to sump pressurization cavity
80 from inadvertently escaping sump pressurization cavity 80 along
shaft 42. In one embodiment, seal assemblies 86 are known as seal
labyrinth seals. Sump oil cavity sump vent 70 extends through sump
pressurization cavity 80.
[0016] FIG. 3 is a schematic illustration of a sump evacuation
system 90 used with lubrication system 28. In the exemplary
embodiment, sump evacuation system 90 includes an air/oil separator
92 and an air pump 94. Air/oil separator 92 is known in the art and
is driven by accessory drive or gear box 32, as is known in the
art. More specifically, air/oil separator 92 includes an inlet 94
and an exhaust 96. In an alternative embodiment, sump evacuation
system 90 does not include air/oil separator 92. Separator inlet 94
is coupled to sump oil cavity sump vent 70, and is know in the art,
separates air exiting sump oil cavity 44 from oil that may have
been carried along with the air.
[0017] Separator exhaust 96 is coupled to air pump 94. More
specifically, air pump 94 is downstream from air/oil separator 92
and includes an intake 98 and an exhaust 100. Air pump intake 98 is
coupled in flow communication with air/oil separator exhaust 96,
and air pump exhaust 100 is coupled in flow communication with a
known engine exhaust and vent system 102 that discharges exhaust
from engine 10. In an alternative embodiment, air pump exhaust 100
is not coupled to vent system 102, but is instead coupled in flow
communication with a known off-engine static air/oil separator.
Sump evacuation system air pump 94 is electrically coupled to an
engine control system (not shown) that controls operation of air
pump 94 and sump evacuation system 90.
[0018] During normal engine operation, oil and compressed air 82
are supplied to sump oil cavity 44, and engine pressures are
sufficient to facilitate reducing inadvertent oil leakage from sump
oil cavity 44. More specifically, during normal engine operation,
compressed air 82 raises an operating pressure within sump
pressurization cavity 80 to be above that of an operating pressure
within sump oil cavity 44. Accordingly, compressed air 82 is forced
into sump oil cavity 44 through sump oil cavity seal assemblies 60,
thus preventing oil from inadvertently leaking from sump oil cavity
44 through seal assemblies 60.
[0019] However, during engine low-power or idle operations, engine
pressures may not be sufficient to facilitate preventing oil from
inadvertently leaking from sump oil cavity 44 through seal
assemblies 60. During such operating conditions, the engine
controller activates sump evacuation system 90 to facilitate
preventing oil from inadvertently leaking from sump oil cavity 44.
More specifically, operation of sump evacuation system air pump 94
draws air from sump oil cavity 44 through air/oil separator 92,
such that an operating pressure within sump oil cavity 44 is
reduced below that of an operating pressure within sump
pressurization cavity 80. As a result, compressed air 82 supplied
to sump pressurization cavity 80 has an operating pressure that is
greater than that of the oil within sump oil cavity 44, and the oil
is prevented from leaking through sump oil cavity seal assemblies
60.
[0020] The above-described sump evacuation system is cost-effective
and highly reliable. The sump evacuation system includes an air
pump that is coupled to the air/oil separator which in-turn is
coupled to the sump oil cavity sump vent. The sump evacuation
system is electrically coupled to an engine control system such
that the evacuation system is activated during low-power and idle
engine operating conditions. During such engine operating
conditions, the air pump reduces an operating pressure within the
bearing assembly sump cavity such that oil leakage from the cavity
is facilitated to be prevented in a cost-effective and reliable
manner.
[0021] While the invention has been described in terms of various
specific embodiments, those skilled in the art will recognize that
the invention can be practiced with modification within the spirit
and scope of the claims.
* * * * *