U.S. patent application number 13/595155 was filed with the patent office on 2014-08-07 for geared turbofan gas turbine engine with reliability check on gear connection.
The applicant listed for this patent is Michael E. McCune, Frederick M. Schwarz. Invention is credited to Michael E. McCune, Frederick M. Schwarz.
Application Number | 20140216053 13/595155 |
Document ID | / |
Family ID | 49001341 |
Filed Date | 2014-08-07 |
United States Patent
Application |
20140216053 |
Kind Code |
A1 |
McCune; Michael E. ; et
al. |
August 7, 2014 |
GEARED TURBOFAN GAS TURBINE ENGINE WITH RELIABILITY CHECK ON GEAR
CONNECTION
Abstract
A gas turbine engine includes a fan and a compressor. A
combustor drives a turbine, including a first turbine with a shaft
to drive the compressor. A fan drive turbine drives the fan through
a speed reduction. A sensor senses a speed of rotation of the fan
and communicates sensed speed information to a control. The control
develops an expected speed for the fan. A problem is identified
should the sensed speed be less than the expected speed by more
than a predetermined amount. A method is also described.
Inventors: |
McCune; Michael E.;
(Colchester, CT) ; Schwarz; Frederick M.;
(Glastonbury, CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
McCune; Michael E.
Schwarz; Frederick M. |
Colchester
Glastonbury |
CT
CT |
US
US |
|
|
Family ID: |
49001341 |
Appl. No.: |
13/595155 |
Filed: |
August 27, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13440085 |
Apr 5, 2012 |
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13595155 |
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13406635 |
Feb 28, 2012 |
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13440085 |
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Current U.S.
Class: |
60/779 ;
60/39.091 |
Current CPC
Class: |
F05D 2270/021 20130101;
F05D 2270/022 20130101; F02K 3/06 20130101; F05D 2260/40311
20130101; F05D 2260/80 20130101; F01D 21/003 20130101 |
Class at
Publication: |
60/779 ;
60/39.091 |
International
Class: |
F01D 21/00 20060101
F01D021/00 |
Claims
1. A gas turbine engine comprising: a fan; a compressor section
having at least one rotor; a combustor; a turbine system, including
a first turbine including a shaft to drive said least one rotor,
and at least a fan drive turbine, said fan drive turbine being
operable to drive said fan through a speed reduction; and a sensor
to sense a speed of rotation of said fan and communicate said
sensed speed to a control, said control being operable to develop
an expected speed for said fan and identify a problem should said
sensed speed be less than the expected speed by more than a
predetermined amount, said predetermined amount being intended to
identify a failure in at least one of gears, a connection and a
shaft in said speed reduction, or a shaft driven by said gears and
in turn driving said fan.
2. The gas turbine engine as set forth in claim 1, wherein said
sensor dynamically determining an angular position of a feature
rotating with the fan by measuring the time of arrival of the
feature, and this dynamically determined angular position being
utilized as the sensed speed, and compared to an expected angular
position of the fan feature, said expected angular position being
said expected speed.
3. The gas turbine engine as set forth in claim 1, wherein a sensor
is associated with said fan drive turbine to sense the angular
position of a feature on said fan drive turbine, and the sensed
angular position of said fan drive turbine feature being utilized
to determine said expected speed of said fan.
4. The gas turbine engine as set forth in claim 1, wherein the
expected speed of said fan is calculated based upon engine
variables.
5. The gas turbine engine as set forth in claim 1, wherein said
engine is shut down should said sensed speed of said fan differ
from said expected speed by more than a predetermined amount.
6. The gas turbine engine as set forth in claim 1, wherein said
control looks for progressive increase in the difference between
the sensed speed and the expected speed.
7. The gas turbine engine as set forth in claim 1, wherein an
intermediate turbine is positioned between said first and fan drive
turbines, and said intermediate turbine drives a compressor
stage.
8. The gas turbine engine as set forth in claim 1, wherein said
speed reduction includes at least one of a flexible coupling and a
spline connection to drive said fan.
9. The gas turbine engine as set forth in claim 8, wherein said
speed reduction directly drives said fan, through a fan shaft.
10-12. (canceled)
13. A method of operating a gas turbine engine comprising: a
turbine system having a first turbine including a shaft driving a
high pressure compressor, and at least a fan drive turbine driving
a fan through a speed reduction; and sensing a speed of rotation of
said fan and comparing a sensed speed to an expected speed for said
fan and identifying a problem should said sensed speed of said fan
be less than the expected speed by more than a predetermined
amount, said predetermined amount being intended to identify a
failure in at least one of gears, a connection and a shaft in said
speed reduction, or a shaft driven by said gears and in turn
driving said fan.
14. The method as set forth in claim 13, wherein said sensed speed
of rotation of said fan is sensed by dynamically determining an
angular position of a feature rotating with the fan by measuring
the time of arrival of the feature, and this dynamically determined
angular position being utilized as the sensed speed, and compared
to an expected angular position of the fan feature, the expected
angular position being said expected speed.
15. The method as set forth in claim 14, wherein sensing the
angular position of a feature rotating with said fan drive turbine,
and said sensed angular position of said feature on said fan drive
turbine being utilized to determine said expected angular position
of said feature rotating with said fan.
16. (canceled)
17. The method as set forth in claim 13, wherein if a progressive
increase in the difference between the sensed speed and the
expected speed is determined, a problem is identified.
18. The method as set forth in claim 13, wherein said fan drive
turbine drives said fan, and an intermediate turbine is positioned
between said first and fan drive turbines, and said intermediate
turbine drives an intermediate compressor.
19. The method as set forth in claim 13, wherein said speed
reduction includes at least one of a flexible coupling and a spline
connection to drive said fan through said speed reduction.
20. The method as set forth in claim 19, wherein said speed
reduction directly drives said fan through a fan shaft.
21. The method as set forth in claim 1, wherein said connection is
a spline and the shaft is flexible.
22. The gas turbine engine as set forth in claim 10, wherein said
predetermined amount being intended to identify a failure in at
least one of gears, a spline connection and a flexible shaft in
said speed reduction, or a shaft driven by said gears and in turn
driving said fan.
23. (canceled)
24. A gas turbine engine comprising: a fan; a compressor section
having a first and second rotor; a combustor; a turbine system,
including: a first turbine including a shaft to drive said second
rotor, at least a fan drive turbine, said fan drive turbine being
operable to drive said fan through a speed reduction; and an
intermediate turbine between said first turbine and said fan drive
turbine, with said intermediate turbine driving said first rotor;
and a sensor to sense a speed of rotation of said fan and
communicate said sensed speed to a control, said control being
operable to develop an expected speed for said fan and to identify
a problem should said sensed speed be less than the expected speed
by more than a predetermined amount, said predetermined amount
being intended to identify a failure in at least one of: gears, a
connection and a shaft in said speed reduction, said connection
including at least one of a flexible coupling and a spline
connection to drive said fan, said predetermined amount also
identifying a failure in said at least one of a flexible coupling
and an end said spline connection; or a shaft driven by said gears
and in turn driving said fan.
25. The gas turbine engine as set forth in claim 24, wherein said
sensor dynamically determining an angular position of a feature
rotating with the fan by measuring the time of arrival of the
feature, and this dynamically determined angular position being
utilized as the sensed speed, and compared to an expected angular
position of the fan feature, said expected angular position being
said expected speed.
26. The gas turbine engine as set forth in claim 24, wherein a
sensor is associated with said fan drive turbine to sense the
angular position of a feature on said fan drive turbine, and the
sensed angular position of said fan drive turbine feature being
utilized to determine said expected speed of said fan.
27. The gas turbine engine as set forth in claim 24, wherein said
engine is shut down should said sensed speed of said fan differ
from said expected speed by more than a predetermined amount.
28. The gas turbine engine as set forth in claim 24, wherein said
control looks for progressive increase in the difference between
the sensed speed and the expected speed.
29. The gas turbine engine as set forth in claim 24, wherein said
speed reduction directly drives said fan, through a fan shaft.
30. The A method of operating a gas turbine engine comprising:
providing a turbine system having: a first turbine including a
shaft driving a high pressure compressor, at least a fan drive
turbine driving a fan through a speed reduction; and an
intermediate turbine, with said intermediate turbine driving a low
pressure compressor; sensing a speed of rotation of said fan and
comparing a sensed speed to an expected speed for said fan;
identifying a problem should said sensed speed of said fan be less
than the expected speed by more than a predetermined amount, said
predetermined amount being intended to identify a failure in at
least one of: gears, a connection and a shaft in said speed
reduction, said connection including at least one of a flexible
coupling and a spline connection to drive said fan, said
predetermined amount also identifying a failure in said at least
one of a flexible coupling and an end said spline connection; or a
shaft driven by said gears and in turn driving said fan.
Description
RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/440,085, filed 5 Apr. 2012, which is a
continuation-in-part of U.S. patent application Ser. No.
13/406,635, filed on 28 Feb. 2012.
BACKGROUND OF THE INVENTION
[0002] This application relates to a gas turbine engine wherein a
fan rotor is driven through a geared connection, and wherein safety
monitoring is performed to ensure that the geared connection has
not failed.
[0003] Gas turbine engines are known, and typically include a fan
delivering air into a compressor. The air is compressed in the
compressor and delivered downstream into a combustion section. The
air is mixed with fuel and ignited, and products of this combustion
pass downstream over turbine rotors.
[0004] There are any number of distinct types of gas turbine
engines. Two common types are so-called "two spool" and "three
spool."
[0005] In a two spool gas turbine engine, there are typically a
pair of compressors and a pair of turbines each having singular or
multiple stages. A shaft connects a high pressure turbine to a high
pressure compressor, and is known as a "high spool." A lower
pressure turbine is connected by a shaft to a low pressure
compressor and is known as a "low spool." The terms "low" and
"high" are relative to each other. Historically, the low spool
shaft also drives the fan rotor, all at one speed with the low
spool.
[0006] Another type of gas turbine engine architecture utilizes a
third spool. In such gas turbine engines there is also an
intermediate spool. A third turbine drives the fan rotor as the
"low spool."
[0007] More recently, a gear reduction has been incorporated
between the drive shaft of a turbine section and the fan rotor.
This feature may be used in two or three spool gas turbine
engines.
[0008] When a gear reduction is used, a resilient coupling may be
provided between the gear train components and the drive shaft
and/or the fan shaft. This transmission path provides any number of
potential failure points. Should the transmission fail, the fan may
no longer be driven. This could prove undesirable, as the speed of
the turbine section driving the fan is typically limited by the
torque required to drive the fan. Once the connection fails, the
turbine section driving the fan could reach undesirably high
speeds.
[0009] In some respects this concern is magnified for three spool
gas turbine engines compared to two spool gas turbine engines. In a
two spool engine, if the gear connection to the fan fails, the low
pressure turbine is still driving the low pressure compressor, and
thus it typically will not reach speeds as undesirably high as
might be the case with the three spool design.
SUMMARY OF THE INVENTION
[0010] In a featured embodiment, a gas turbine engine has a fan, a
compressor section, a combustor, and a turbine system. The turbine
section includes a first turbine having a shaft to drive the
compressor, and at least a fan drive turbine. The fan drive turbine
is operable to drive the fan through a speed reduction. A sensor
senses a speed of rotation of the fan and communicates the sensed
speed to a control. The control is operable to develop an expected
speed for the fan and identify a problem should the sensed speed be
less than the expected speed by more than a predetermined
amount.
[0011] In another embodiment according to the previous embodiment,
the sensor dynamically determines an angular position of a feature
rotating with the fan by measuring the time of arrival of the
feature. This dynamically determined angular position is utilized
as the sensed speed and compared to an expected angular position of
the fan feature. The expected angular position is the expected
speed.
[0012] In another embodiment according to any of the previous
embodiments, a sensor is associated with the fan drive turbine to
sense the angular position of a feature on the fan drive turbine.
The sensed angular position of the fan drive turbine feature is
utilized to determine the expected speed of the fan.
[0013] In another embodiment according to any of the previous
embodiments, the expected speed of the fan is calculated based upon
engine variables.
[0014] In another embodiment according to any of the previous
embodiments, the engine is shut down should the sensed speed of the
fan differ from the expected speed by more than a predetermined
amount.
[0015] In another embodiment according to any of the previous
embodiments, the control looks for progressive increase in the
difference between the sensed speed and the expected speed.
[0016] In another embodiment according to any of the previous
embodiments, an intermediate turbine is positioned between the
first and fan drive turbines, and the intermediate turbine drives a
compressor stage.
[0017] In another embodiment according to any of the previous
embodiments, the speed reduction includes at least one of a
flexible coupling and a spline connection to drive the fan.
[0018] In another embodiment according to any of the previous
embodiments, the speed reduction directly drives the fan through a
fan shaft.
[0019] In another featured embodiment, a gas turbine engine has a
fan, a compression section including at least a first compressor
and a second compressor downstream of the first compressor, a
combustor, and a turbine system. The turbine system has a first
turbine including a shaft to drive the second compressor, and at
least a fan drive turbine. The fan drive turbine is operable to
drive the fan through a speed reduction, an intermediate turbine
positioned between the first and fan drive turbines. The
intermediate turbine drives the first compressor. A sensor senses
rotation information of the fan and communicates the sensed
information to a control. The control is operable to develop
expected information for the fan and identify a problem should the
sensed information be different than the expected information by
more than a predetermined amount. A sensor is associated with the
fan drive turbine to sense rotation information of the fan drive
turbine. Information relative to the fan drive turbine is utilized
to determine the expected information of the fan. The engine is
shut down should the sensed information differ from the expected
information by more than a predetermined amount. The sensed
rotation information is based upon a time of arrival of a feature
that rotates with the fan. The expected speed is developed by
sensing a time of arrival of a feature rotating with the fan drive
turbine to develop said expected information.
[0020] In another embodiment according to the previous embodiment,
the speed reduction includes at least one of a flexible coupling
and a spline connection to drive the fan through the speed
reduction.
[0021] In another embodiment according to any of the previous
embodiments, the speed reduction directly drives the fan through a
fan shaft.
[0022] In another featured embodiment, a method of operating a gas
turbine engine includes a shaft driving a high compressor, and at
least a fan drive turbine driving a fan through a speed reduction.
A speed of rotation of the fan is sensed and compared to an
expected speed for the fan. A problem is identified should the
sensed speed of the fan be less than the expected speed by more
than a predetermined amount.
[0023] In another embodiment according to the previous embodiment,
the sensed speed of rotation of the fan is sensed by dynamically
determining an angular position of a feature rotating with the fan
by measuring the time of arrival of the feature. This dynamically
determined angular position is utilized as the sensed speed, and
compared to an expected angular position of the fan feature. The
expected angular position is the expected speed.
[0024] In another embodiment according to any of the previous
embodiments, the angular position of a feature rotating with the
fan drive turbine is sensed and utilized to determine the expected
angular position of the feature rotating with the fan.
[0025] In another embodiment according to any of the previous
embodiments, the expected speed is calculated based upon engine
variables.
[0026] In another embodiment according to any of the previous
embodiments, if a progressive increase in the difference between
the sensed speed and the expected speed, a problem is
identified.
[0027] In another embodiment according to any of the previous
embodiments, the fan drive turbine drives the fan. An intermediate
turbine is positioned between the first and fan drive turbines. The
intermediate turbine drives an intermediate compressor.
[0028] In another embodiment according to any of the previous
embodiments, the speed reduction includes at least one of a
flexible coupling and a spline connection to drive the fan through
the speed reduction.
[0029] In another embodiment according to any of the previous
embodiments, the speed reduction directly drives the fan through a
fan shaft.
[0030] These and other features of this invention will be best
understood from the following specification and drawings, the
following of which is a brief description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 schematically shows a first embodiment.
[0032] FIG. 2 schematically shows a second embodiment.
DETAILED DESCRIPTION
[0033] FIG. 1 shows a gas turbine engine 20 which has three spools.
A fan 22 delivers bypass air B and core airflow C. The core airflow
C passes into an intermediate pressure compressor 24. The air
compressed by the intermediate pressure compressor 24 passes into a
high pressure compressor 26. The air is compressed and delivered
across a combustion section 28, where it is ignited. Products of
this combustion pass downstream into a high pressure turbine 30. A
high spool is defined by the high pressure turbine 30, which drives
the shaft 32, which in turn drives the high pressure compressor
26.
[0034] The products of combustion pass downstream of the high
pressure turbine 30 into an intermediate pressure turbine 34. The
intermediate pressure turbine 34 drives a shaft 36, which in turn
drives the intermediate pressure compressor 24 as an intermediate
spool. From the intermediate pressure turbine 34 the products of
combustion pass downstream over a low pressure turbine 38. The low
pressure turbine 38 is driven to rotate, and in turn rotates the
shaft 40. The shaft 40 drives a gear transmission 42 to rotate the
fan 22. The speed reduction mechanism 42 is typically an epicyclic
gear reduction unit, so that the fan rotates at a slower speed than
the low pressure turbine 38, which is the fan driving turbine. As
known, the terms "low," "high," and "intermediate" are relative to
each other.
[0035] The gear transmission 42 includes gear components, and a
coupling and/or a spline connection 46, shown somewhat
schematically. This feature 46 may also be a flexible connection
allowing for the engine to bend under thrust loads without causing
mis-aligned input to the gearbox. In addition, the gear components
42 typically drive a fan shaft 44 which is connected to drive the
fan 22. It will be understood that this figure is quite schematic,
and a worker of ordinary skill in the art would recognize the types
of flexible couplings, etc., along with the drive connections which
may be used between these components.
[0036] As mentioned above, should any of the components 42/44/46
fail, then the low pressure turbine 38 might begin to rotate at
undesirably high speeds, as it is no longer called upon to drive
the fan rotor 22.
[0037] As used herein the term `speed` is construed to mean the
time at which an applicable engine component arrives at a
particular rotation location, which arrival time may be compared to
the time of arrival of another engine component. Similarly, the
term `overspeed` is construed to define the situation in which an
applicable engine component arrives at a particular rotation
location sooner than it should as compared to the arrival time of
another component that is intended to have an arrival time that is
historically consistent between the two features. Conversely, the
term `underspeed` is construed to define the situation in which an
applicable engine component arrives at a particular rotation
location later than it should as compared to the historical arrival
time of another component. Also, the "term time of arrival" relates
to the relative time of arrival of two features: a reference
feature at one end of the spool assembly relative to a feature at
or near the other end of the spool and this time of arrival
difference can optionally be converted into a difference in the
angular dimension of the two features.
[0038] More generally, the term "speed" can be taken to be any sort
of rotation information with regard to the position of a feature
rotating with the fan, and a way of reaching an expected value for
that rotation information.
[0039] A sensor 45 is positioned adjacent blades of the fan rotor
22 or at the tip of the fan blades tip or at bumps or other
features on the shaft 44 driving the fan hub. It should be
understood that any type of sensor may be utilized, however, one
disclosed sensor senses the time of arrival of an edge of the
blades at their tip associated with the fan rotor 22. Such sensors
are known, and have been utilized for any number of
applications.
[0040] The time-of-arrival information from a sensor 45 is
delivered to an electronic engine control 100. A second sensor 242
senses the time of arrival of bumps or other features on the shaft
40, and provides the information to the control 100. Again, any
other type sensor may replace sensor 242 as long as the sensor and
the accompanying control can precisely measure the time of arrival
of a bump or other timing feature.
[0041] The sensor 242 is shown positioned on the shaft 40, and
intermediate the low pressure turbine 38 and the gear connection
42. An alternative position 142 is shown on the opposed side of the
shaft 40 from the low pressure turbine 38.
[0042] The control 100 takes in time of arrival information of each
bump on the shaft individually from the sensor 45 and compares it
to time of arrival of individual bumps or other timing features on
the rotor from the sensor 242 or 142. The control 100 develops an
expected time of arrival based upon the speed sensed by sensors
242/142 and a gear ratio across the speed reduction 42 (any, or
all, of wind up produced in the shaft through normal idle,
take-off, climb and cruise operation and also the transient wind up
caused by power changes accelerations and decelerations may also be
utilized).
[0043] The control 100 may be programmed to anticipate differences
in the arrival time and speed providing for allowable shifts caused
by power, ambient temperature, altitude, and creep. The control 100
may also be programmed to compensate for shaft windup due to torque
levels, and with possible corrections for transient conditions such
as the exertion of power and the time since such an exertion began.
In addition, manufacturing tolerances and rotor assembly
circumstances may be taken out at an engine's initial run, or after
heavy maintenance, and thus are cancelled out or not interpreted as
a concern.
[0044] The sensors 45, 142 and 242 may be any type of sensor. The
locations may be as shown, however, any other location which is
able to provide rotation information of the rotor 22, and a
location on the opposed side of the gear connection 42 may be
utilized.
[0045] If the arrival time or other rotation speed information of
the fan 22 is significantly in error, then the engine may be shut
down as a precaution should the turbine overspeed. If the arrival
time of other speed information of the fan rotor 22 progressively
becomes more and more different from that which is expected, the
engine may be shut down or it may be flagged for inspection or
maintenance. This decision may be made based on a rate of
deterioration and the extent of the angular difference between the
features ahead of and behind the gearbox.
[0046] FIG. 2 shows an alternative embodiment, wherein a sensor 242
or 142 is not used. Instead, information 200 is utilized, which
provides some other variable, which allows an expectation of the
time of arrival or other speed to be seen by the sensor 45. As an
example, the amount of fuel being delivered into the engine would
provide an expected thrust level, and an expected speed of the fan.
Any number of other engine related variables can be relied upon to
provide this information such as fuel flow, high rotor speed,
altitude, flight mach number and/or ambient temperature to provide
the basis for calculating air flow and the input energy to the fan
drive turbine and ultimately the fan across the gear system.
Otherwise, the system will operate as in the first embodiment.
[0047] While a three spool design is shown it should be understood
that the teachings may extend to a two spool design. In some
respects, the teachings can extend to any number of gas turbine
engine configurations, including a configuration which has a single
compressor stage driven by a turbine stage with a fan drive turbine
driving only a fan. Of course, the teachings would also extend to
the standard two-spool design wherein the fan drive turbine also
drives an intermediate or low stage compressor.
[0048] 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.
* * * * *