U.S. patent application number 13/598037 was filed with the patent office on 2014-07-24 for systems and methods to control variable stator vanes in gas turbine engines.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. The applicant listed for this patent is Wayne R. Bowen, Harry McFarland Jarrett, JR., Sasi Kumar Tippabhotla, Jayakrishna Velampati, Padmapriya Vijayakumar. Invention is credited to Wayne R. Bowen, Harry McFarland Jarrett, JR., Sasi Kumar Tippabhotla, Jayakrishna Velampati, Padmapriya Vijayakumar.
Application Number | 20140205424 13/598037 |
Document ID | / |
Family ID | 51207815 |
Filed Date | 2014-07-24 |
United States Patent
Application |
20140205424 |
Kind Code |
A1 |
Velampati; Jayakrishna ; et
al. |
July 24, 2014 |
Systems and Methods to Control Variable Stator Vanes in Gas Turbine
Engines
Abstract
Embodiments of the present application include a variable stator
vanes control mechanism for a gas turbine engine. The control
mechanism includes a moveable actuation rod in operative
communication with a first unison ring such that movement of the
actuation rod drives the first unison ring. The control mechanism
also includes a bell crank mechanism in operative communication
with the first unison ring and a second unison ring such that
movement of the first unison ring drives the second unison
ring.
Inventors: |
Velampati; Jayakrishna;
(Bangalore, IN) ; Jarrett, JR.; Harry McFarland;
(Greenville, SC) ; Bowen; Wayne R.; (West Chester,
OH) ; Vijayakumar; Padmapriya; (Bangalore, IN)
; Tippabhotla; Sasi Kumar; (Bangalore, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Velampati; Jayakrishna
Jarrett, JR.; Harry McFarland
Bowen; Wayne R.
Vijayakumar; Padmapriya
Tippabhotla; Sasi Kumar |
Bangalore
Greenville
West Chester
Bangalore
Bangalore |
SC
OH |
IN
US
US
IN
IN |
|
|
Assignee: |
GENERAL ELECTRIC COMPANY
Schenectady
NY
|
Family ID: |
51207815 |
Appl. No.: |
13/598037 |
Filed: |
August 29, 2012 |
Current U.S.
Class: |
415/1 ;
415/151 |
Current CPC
Class: |
F04D 29/563
20130101 |
Class at
Publication: |
415/1 ;
415/151 |
International
Class: |
F04D 27/00 20060101
F04D027/00 |
Claims
1. A variable stator vanes control mechanism for a gas turbine
engine, comprising: a first unison ring; a second unison ring; a
moveable actuation rod in operative communication with the first
unison ring such that movement of the actuation rod drives the
first unison ring in a first direction; and a bell crank mechanism
in operative communication with the first unison ring and the
second unison ring such that movement of the first unison ring in
the first direction drives the second unison ring in a second
direction.
2. The control mechanism of claim 1, wherein the second direction
is opposite the first direction.
3. The control mechanism of claim 1, wherein the second direction
is similar to the first direction.
4. The control mechanism of claim 1, wherein the bell crank
mechanism comprises: a pivot; a first turnbuckle operatively
connecting the first unison ring to the pivot; and a second
turnbuckle operatively connecting the second unison ring to the
pivot.
5. The control mechanism of claim 4, wherein the first turnbuckle
and the second turnbuckle are attached to the pivot such that
rotation of the pivot drives the first turnbuckle and the second
turnbuckle in opposite directions.
6. The control mechanism of claim 4, wherein a relative movement
between the first unison ring and the second unison ring can be
varied by varying the dimensions of the pivot, the first
turnbuckle, and the second turnbuckle.
7. The control mechanism of claim 1, wherein the first unison ring
is in operative communication with a plurality of variable stator
vanes.
8. The control mechanism of claim 1, wherein the second unison ring
is in operative communication with a plurality of variable stator
vanes.
9. The control mechanism of claim 1, wherein the bell crank
mechanism is at least partially secured to a casing of a
compressor.
10. The control mechanism of claim 1, wherein the moveable actuator
rod is at least partially secured to a casing of a compressor.
11. The control mechanism of claim 1, further comprising one or
more additional unison rings in operative communication with the
bell crank mechanism such that movement of the first unison ring in
the first direction drives the one or more additional unison rings
in the first or second direction respectively.
12. A method to control variable stator vanes in a gas turbine
engine, comprising: actuating a moveable actuation rod in operative
communication with a first unison ring such that movement of the
actuation rod drives the first unison ring in a first direction;
and driving a bell crank mechanism in operative communication with
the first unison ring and a second unison ring such that movement
of the first unison ring in the first direction drives the second
unison ring in a second direction.
13. The method of claim 12, wherein the second direction is
opposite the first direction.
14. The method of claim 12, wherein the second direction is similar
to the first direction.
15. A variable stator vanes control mechanism for a gas turbine
engine, comprising: a compressor having a compressor casing; a
first unison ring disposed about the compressor casing; a second
unison ring disposed about the compressor casing; a moveable
actuation rod attached to the compressor casing and in operative
communication with the first unison ring such that movement of the
actuation rod drives the first unison ring in a first direction
about the compressor casing; and a bell crank mechanism attached to
the compressor casing and in operative communication with the first
unison ring and the second unison ring such that movement of the
first unison ring about the compressor casing in the first
direction drives the second unison ring in a second direction about
the compressor casing.
16. The control mechanism of claim 15, wherein the second direction
is opposite the first direction.
17. The control mechanism of claim 15, wherein the second direction
is similar to the first direction.
18. The control mechanism of claim 15, wherein the bell crank
mechanism comprises: a pivot; a first turnbuckle operatively
connecting the first unison ring to the pivot; and a second
turnbuckle operatively connecting the second unison ring to the
pivot.
19. The control mechanism of claim 18, wherein a relative movement
between the first unison ring and the second unison ring can be
varied by varying the dimensions of the pivot, the first
turnbuckle, and the second turnbuckle.
20. The control mechanism of claim 15, wherein the first unison
ring and the second unison ring are in operative communication with
a plurality of respective variable stator vanes.
Description
FIELD OF THE INVENTION
[0001] Embodiments of the present application relate generally to
gas turbine engines and more particularly to systems and methods to
control variable stator vanes in gas turbine engines.
BACKGROUND OF THE INVENTION
[0002] During operation of a gas turbine engine using a multi-stage
axial compressor, a turbine rotor is turned at high speeds by a
turbine so that air is continuously induced into the compressor.
The air is accelerated by rotating blades and swept rearwards onto
adjacent rows of variable stator vanes. Each rotor blade/variable
stator vane stage increases the pressure of the air.
[0003] In addition to translating the kinetic energy of the air
into pressure, the variable stator vanes also serve to correct the
deflection given to the air by the rotor blades and to present the
air at the correct angle to the next stage of rotor blades.
Pivoting the variable stator vanes permits the flow capacity of the
compressor or turbine to be changed, thereby ensuring that the flow
capacity is always at an optimum value for the particular operating
conditions of the gas turbine engine. Accordingly, there is a need
to control the angle of the variable stator vanes.
BRIEF DESCRIPTION OF THE INVENTION
[0004] Some or all of the above needs and/or problems may be
addressed by certain embodiments of the present application.
According to one embodiment, there is disclosed a variable stator
vane control mechanism for a gas turbine engine. The control
mechanism includes a moveable actuation rod in operative
communication with a first unison ring such that movement of the
actuation rod drives the first unison ring in a first direction.
The control mechanism also includes a bell crank mechanism in
operative communication with the first unison ring and a second
unison ring such that movement of the first unison ring in the
first direction drives the second unison ring in a second
direction.
[0005] According to another embodiment, there is disclosed a method
to control variable stator vanes in a gas turbine engine. The
method includes actuating a moveable actuation rod in operative
communication with a first unison ring such that movement of the
actuation rod drives the first unison ring in a first direction.
The method also includes driving a bell crank mechanism in
operative communication with the first unison ring and a second
unison ring such that movement of the first unison ring in the
first direction drives the second unison ring in a second
direction.
[0006] Further, according to another embodiment, there is disclosed
a variable stator vanes control mechanism for a gas turbine engine.
The gas turbine engine may include a compressor having a compressor
casing. The control mechanism may include a moveable actuation rod
attached to the compressor casing and in operative communication
with a first unison ring such that movement of the actuation rod
drives the first unison ring in a first direction about the
compressor casing. The control mechanism may also include a bell
crank mechanism attached to the compressor casing and in operative
communication with the first unison ring and a second unison ring
such that movement of the first unison ring about the compressor
casing in the first direction drives the second unison ring in a
second direction about the compressor casing.
[0007] Other embodiments, aspects, and features of the invention
will become apparent to those skilled in the art from the following
detailed description, the accompanying drawings, and the appended
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Reference will now be made to the accompanying drawings,
which are not necessarily drawn to scale, and wherein:
[0009] FIG. 1 is a schematic of an example diagram of a gas turbine
engine with a compressor, a combustor, and a turbine, according to
an embodiment.
[0010] FIG. 2 is a schematic of an example portion of a compressor
assembly, according to an embodiment.
[0011] FIG. 3 is a perspective view of a portion of a compressor
assembly, according to an embodiment.
[0012] FIG. 4 is a perspective view of a portion of a compressor
assembly, according to an embodiment.
[0013] FIG. 5 is a perspective view of a portion of a compressor
assembly, according to an embodiment.
[0014] FIG. 6 is a perspective view of a portion of a compressor
assembly, according to an embodiment.
[0015] FIG. 7 is a perspective view of a portion of a compressor
assembly, according to an embodiment.
[0016] FIG. 8 is a perspective view of a portion of a compressor
assembly, according to an embodiment.
[0017] FIG. 9 is a perspective view of a portion of a compressor
assembly, according to an embodiment.
[0018] FIG. 10 is a perspective view of a portion of a compressor
assembly, according to an embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0019] Illustrative embodiments will now be described more fully
hereinafter with reference to the accompanying drawings, in which
some, but not all embodiments are shown. The present application
may be embodied in many different forms and should not be construed
as limited to the embodiments set forth herein. Like numbers refer
to like elements throughout.
[0020] Illustrative embodiments are directed to, among other
things, systems and methods to control variable stator vanes in gas
turbine engines. FIG. 1 shows a schematic view of a gas turbine
engine 10 as may be used herein. As is known, the gas turbine
engine 10 may include a compressor 12. The compressor 12 compresses
an incoming flow of air 14. The compressor 12 delivers the
compressed flow of air 14 to a combustor 16. The combustor 16 mixes
the compressed flow of air 14 with a pressurized flow of fuel 18
and ignites the mixture to create a flow of combustion gases 20.
Although only a single combustor 16 is shown, the gas turbine
engine 10 may include any number of combustors 16. The flow of
combustion gases 20 is in turn delivered to a turbine 22. The flow
of combustion gases 20 drives the turbine 22 so as to produce
mechanical work. The mechanical work produced in the turbine 22
drives the compressor 12 via a shaft 24 and an external load 26
such as an electrical generator and the like.
[0021] The gas turbine engine 10 may use natural gas, various types
of syngas, and/or other types of fuels. The gas turbine engine 10
may be any one of a number of different gas turbine engines offered
by General Electric Company of Schenectady, N.Y., including, but
not limited to, those such as a 7 or a 9 series heavy duty gas
turbine engine and the like. The gas turbine engine 10 may have
different configurations and may use other types of components.
[0022] Other types of gas turbine engines also may be used herein.
Multiple gas turbine engines, other types of turbines, and other
types of power generation equipment also may be used herein
together.
[0023] FIG. 2 depicts a section of the compressor 12 of the gas
turbine engine 10 of FIG. 1. The compressor 12 includes a tubular
casing 28. Sets of variable stator vanes 30 are mounted within the
casing 28 circumferentially about the central axis of the
compressor 12. Corresponding sets of rotor vanes 32 are mounted
downstream of each set of variable stator vanes 30. Each variable
stator vane 30 terminates at the casing 28 in a stem 34. The stem
34 is rotatable in a bush bearing 36 on the outside of the casing
28.
[0024] Located externally of the casing 28 and adjacent to each set
of variable stator vanes 30 are unison rings 38 extending
circumferentially about the casing 28. The vane stems 34 of each
set of variable stator vanes 30 are connected to the corresponding
unison ring 38 by a respective lever 40. One end of the lever 40 is
clamped to the end of the vane stem 34 by a bolt 42 so that there
is no relative movement between the stem 34 and the lever 40. The
other end of the lever 40 is connected to the unison ring 38 by a
pin 44 rotatable in a bush bearing located in the unison ring
38.
[0025] The unison ring 38 is arranged so that it may be rotated
about the central axis of the compressor section 12 in either
direction of arrow 9. Consequently, rotation of the unison ring 38
causes rotation of each variable stator vane 30 via the levers 40
and thus enables the variable stator vanes 30 to assume required
angles of incidence to the incoming air.
[0026] FIGS. 3 and 4 depict an embodiment of a variable stator
vanes control mechanism 100. The variable stator vanes control
mechanism 100 enables the transfer of motion from one unison ring
to another using only one actuator. The variable stator vanes
control mechanism 100 may include a moveable actuation rod 102. The
moveable actuation rod 102 may be in operative communication with a
first unison ring 104 such that movement of the actuation rod 102
drives the first unison ring 104 in a first direction 106 about the
central axis of the casing 108. Rotation of the first unison ring
104 causes rotation of each variable stator vane 110 connected to
the first unison ring by the levers 112.
[0027] The variable stator vanes control mechanism 100 may also
include a bell crank mechanism 114. The bell crank mechanism 114
may be in operative communication with the first unison ring 104.
The bell crank mechanism 114 may also be in operative communication
with a second unison ring 116 such that movement of the first
unison ring 104 in the first direction 106 translates movement, by
way of the bell crank mechanism 114, to the second unison ring 116
in a second direction 118 that is opposite the first direction 106
of the first unison ring 104. Rotation of the second unison ring
116 causes rotation of each variable stator vane 110 connected to
the second unison ring 116 by the levers 112.
[0028] Still referring to FIGS. 3 and 4, the bell crank mechanism
114 may include a pivot 120, a first turnbuckle 122, and a second
turnbuckle 124. The first turnbuckle 122 operatively connects the
first unison ring 104 to the pivot 120. Similarly, the second
turnbuckle 124 operatively connects the second unison ring 116 to
the pivot 120. The first turnbuckle 122 and the second turnbuckle
124 are attached to the pivot 120 such that rotation of the pivot
120 drives the first turnbuckle 122 and the second turnbuckle 124
in opposite directions.
[0029] In operation, the movable actuator rod 102 actuates the
first unison ring 104 thereby rotating the first unison ring 104 in
the first direction 106 about the casing 108. As the first unison
ring 104 rotates about the casing 108 in the first direction 106,
it drives the first turnbuckle 122. The first turnbuckle 122 then
applies a pivoting force to the pivot 120. The pivoting of the
pivot 120 causes the second turnbuckle 124 to drives the second
unison ring 116 thereby causing the second unison ring 116 to
rotate in the second direction 118 about the casing 108. In this
embodiment, the second direction 118 and the first direction 106
are opposite of each other. The rotation of the first unison ring
104 and the second unison ring 116 causes the respective variable
stator vanes 110 attached to each unison ring to rotate in opposite
directions due to the movement of the levers 112. Accordingly, the
angle of the variable stator vanes 110 may be adjusted with the
variable stator vanes control mechanism 100.
[0030] As described above, the first direction 106 and the second
direction 118 are relative to each other. Accordingly, the first
direction 106 and the second direction 118 may be any direction
about the casing 108. Moreover, the moveable actuation rod 102 may
be in operative communication with the first unison ring 104, the
second unison ring 106, or the bell crank mechanism 114.
[0031] In certain embodiments, the bell crank mechanism 114 may be
at least partially secured to the casing 108 of the compressor. In
other embodiments, the moveable actuator rod 102 may be at least
partially secured to the casing 108 of the compressor. One will
appreciate, however, that the bell crank mechanism 114 and the
moveable actuator rod 102 may be at least partially secured at any
location on or about the gas turbine engine.
[0032] A relative movement between the first unison ring 104 and
the second unison ring 116 and the angle of the variable stator
vanes 110 may be adjusted by varying the dimensions of the pivot
12, the first turnbuckle 122, and the second turnbuckle 124.
Moreover, the angle of the variable stator vanes 110 may be varied
by varying the length of the levers 112.
[0033] In an embodiment, as depicted in FIG. 5, the variable stator
vanes control mechanism 100 may enable the transfer of motion from
one unison ring to another using only one actuator. In this
embodiment, however, the first unison ring and the second unison
ring may rotate in the same direction. For example, the bell crank
mechanism 114 may include a pivot 120, a first turnbuckle 122, and
a second turnbuckle 124. The first turnbuckle 122 operatively
connects the first unison ring 104 to the pivot 120. Similarly, the
second turnbuckle 124 operatively connects the second unison ring
116 to the pivot 120. The first turnbuckle 122 and the second
turnbuckle 124 may be attached to the pivot 120 such that rotation
of the pivot 120 drives the first turnbuckle 122 and the second
turnbuckle 124 in the same direction. Accordingly, in operation,
the movable actuator rod actuates the first unison ring 104 thereby
rotating the first unison ring 104 in a first direction 106 about
the casing 108. As the first unison ring 104 rotates about the
casing 108 in the first direction 106, it drives the first
turnbuckle 122. The first turnbuckle 122 then applies a pivoting
force to the pivot 120. The pivoting of the pivot 120 causes the
second turnbuckle 124 to drive the second unison ring 116 thereby
causing the second unison ring 116 to rotate in the first direction
about the casing 108. The rotation of the first unison ring 104 and
the second unison ring 116 causes the respective variable stator
vanes 110 attached to each unison ring to rotate in the same
direction due to the movement of the levers 112.
[0034] The embodiments as depicted in FIGS. 3-5 may include one or
more additional unison rings in operative communication with the
bell crank mechanism such that movement of the first unison ring in
the first direction drives the one or more additional unison rings
in the first or second direction respectively.
[0035] FIG. 6 depicts an embodiment of a variable stator vanes
control mechanism 200. The variable stator vanes control mechanism
200 enables the transfer of motion from one unison ring to another
using only one actuator. The variable stator vanes control
mechanism 200 may include a moveable actuation rod 202 in operative
communication with a first unison ring 204. The moveable actuation
rod 202 may actuate the first unison ring 204. The variable stator
vanes control mechanism 200 may also include a linkage 206 in
operative communication with the first unison ring 204 and a second
unison ring 208 such that movement of the first unison ring 204
drives the second unison ring 208. This embodiment is similar to
the previously described embodiments, except that it does not
include the bell crank mechanism. Instead, this embodiment provides
a direct linkage 206 between the unison rings 204 and 208.
Accordingly, in this embodiment, the linkage 206 translates
movement from the actuated first unison ring 204 to the second
unison ring 208 in the same direction. In certain aspects, the
linkage 206 may pull the second unison ring 208. In other aspects,
the linkage 206 may push the second unison ring 208.
[0036] Still referring to FIG. 6, in operation, the movable
actuator rod 202 is attached to the casing 210 and actuates the
first unison ring 204 thereby rotating the first unison ring 204
about the casing 210. As the first unison ring 204 rotates about
the casing 210, it drives the linkage 206. The linkage 206 may be a
turnbuckle. The linkage 206 then applies a force to the second
unison ring 208 thereby causing the second unison ring 208 to
rotate about the casing 210. In this embodiment, the first unison
ring 204 and the second unison ring 206 rotate in the same
direction about the casing 210. The rotation of the first unison
ring 204 and the second unison ring 206 causes the respective
variable stator vanes attached to each unison ring by way of the
respective levers 212 to rotate. Accordingly, the angle of the
variable stator vanes may be adjusted with the variable stator
vanes control mechanism 200.
[0037] The embodiment as depicted in FIG. 6 may include one or more
additional unison rings in operative communication with one or more
additional linkages such that movement of the first unison ring in
the first direction drives the one or more additional unison rings
respectively.
[0038] FIGS. 7 and 8 depict an embodiment of a variable stator
vanes control mechanism 300. The variable stator vanes control
mechanism 300 enables the actuation of multiple unison rings using
only one actuator. The variable stator vanes control mechanism 300
may include a moveable actuation rod 302. The moveable actuation
rod 302 may be in operative communication with a torque shaft 304
such that the movable actuation rod 302 rotates the torque shaft
304. A first unison ring 306 may be in operative communication with
the torque shaft 304 via a turnbuckle 305 such that rotation of the
torque shaft 304 drives the first unison ring 306 in a first
direction 308 about a central axis of the casing 310. Rotation of
the first unison ring 306 causes rotation of each variable stator
vane 312 connected to the first unison 306 ring by the levers 314.
Similarly, a second unison ring 316 may be in operative
communication with the torque shaft 304 via a turnbuckle 307 such
that rotation of the torque shaft 304 drives the second unison ring
316 in a second direction 318 about the central axis of the casing
310. Rotation of the second unison ring 316 causes rotation of each
variable stator vane 312 connected to the second unison 316 ring by
the levers 314.
[0039] As described above, the first direction 308 and the second
direction 318 are relative. The first direction 308 and the second
direction 318 may be the same direction or different directions
about the casing 310. For example, in embodiments where the first
direction and the second direction are the same, the turnbuckles
305 and 307 may be attached on the same side of the torque shaft.
Conversely, in embodiments where the first direction and the second
direction are different, the turnbuckles 305 and 307 may be
attached on opposite sides of the torque shaft. The first direction
308 and the second direction 318 may be any direction about the
casing 310. Moreover, the moveable actuation rod 302 may be in
operative communication with the first unison ring 306, the second
unison ring 316, or the torque shaft 304.
[0040] In operation, the movable actuator rod 302 is attached to
the casing 310 and actuates the torque shaft 304 thereby rotating
the torque shaft 304. The turnbuckle 305 connects the first unison
ring 306 to the torque shaft 304, and the turnbuckle 307 connects
the second unison ring 316 to the torque shaft 304. As the torque
shaft 304 rotates, the turnbuckles 305 and 307 drive the first
unison ring 306 and the second unison ring 316 about the compressor
casing 310. The rotation of the first unison ring 306 and the
second unison ring 316 causes the respective variable stator vanes
attached to each unison ring by the respective levers 314 to
rotate. Accordingly, the angle of the variable stator vanes may be
adjusted with the variable stator vanes control mechanism 300. One
will appreciate that one or more additional unison rings may be in
communication with the torque shaft by one or more respective
turnbuckles.
[0041] In certain embodiments, the moveable actuator rod 302 may be
at least partially secured to the casing 310 of the compressor. One
will appreciate, however, that the moveable actuator rod 302 may be
at least partially secured at any location on or about the gas
turbine engine. Moreover, the torque shaft 304 may be rotatably
supported about the casing 310 of the compressor by a support
structure 320. The support structure 320 may be any configuration
that facilitates the rotation of the torque shaft about the
compressor casing 310.
[0042] FIGS. 9 and 10 depict an embodiment of a variable stator
vanes control mechanism 400. The variable stator vanes control
mechanism 400 enables the actuation of two variable stator vanes
stages using only one actuator and a system of gears. The actuator
engages the gear system which engages the two stages of variable
stator vanes thereby adjusting the variable stator vanes.
[0043] The variable stator vanes control mechanism 400 may include
a moveable actuation rod 402. The moveable actuation rod 402 may be
attached to the casing 404 or any other location on or about the
gas turbine engine. The moveable actuation rod 402 may also be
attached to a gear ring 406. The gear ring 406 may be disposed
about the compressor casing 404 such that the gear ring 406 rotates
about the compressor casing 404 when actuated by the moveable
actuation rod 402. A rub block 408 may be disposed between the
casing 404 and the gear ring 406 to facilitate smooth rotation of
the gear ring 406 about the casing 404.
[0044] A number of variable stator vanes 410 may be disposed on a
first side 412 and a second side 414 of the gear ring 406. The
variable stator vanes 410 form a first compressor stage and a
second compressor stage respectively on each side of the gear ring
406. The variable stator vanes 410 may include gear stems 416. The
gear stems 416 may be in operative communication with the gear ring
406.
[0045] In operation, the movable actuation rod 402 is attached to
the casing 404 and actuates the gear ring 406 thereby rotating the
gear ring 406 about the casing 404. The gear stems 416 of the
variable stator vanes 410 are in operative communication with the
gear ring 406 such that as the gear ring 406 rotates about the
casing 404, the gear stems 416 of the variable stator vanes 410 are
rotated. The rotation of the gear stems 416 adjusts the angle of
the variable stator vanes 410.
[0046] In certain embodiments, the rotation of the variable stator
vanes 410 may be controlled by the addition of gears or gear train
type mechanisms operatively disposed between the gear stems and the
gear ring. For example, as depicted in FIGS. 9 and 10, additional
gears 418 are operatively disposed between the gear ring 406 and
the respective gear stems 416 of the first compressor stage. The
addition of additional gears 418 enables the first compressor stage
of variable stator vanes and the second compressor stage of
variable stator vanes to rotate in the same direction. In contrast,
if the gear stems 416 of the variable stator vanes 410 were in
direct communication with the gear ring 406, the variable stator
vanes 410 would rotate in opposite directions.
[0047] One will appreciate that any number of additional gears or
gear train type mechanisms may be operatively disposed between the
gear ring and the gear stems to facilitate a desired rotation.
Moreover, the gear ratio and the number of gear teeth may be
adjusted to control the schedule between variable stator vane
stages.
[0048] Although embodiments have been described in language
specific to structural features and/or methodological acts, it is
to be understood that the disclosure is not necessarily limited to
the specific features or acts described. Rather, the specific
features and acts are disclosed as illustrative forms of
implementing the embodiments.
* * * * *