U.S. patent application number 13/792739 was filed with the patent office on 2014-09-11 for gas turbine engine with internal electromechanical device.
This patent application is currently assigned to PRATT & WHITNEY CANADA CORP.. The applicant listed for this patent is PRATT & WHITNEY CANADA CORP.. Invention is credited to Andreas ELEFTHERIOU, Richard KOSTKA, David MENHEERE.
Application Number | 20140252769 13/792739 |
Document ID | / |
Family ID | 51455195 |
Filed Date | 2014-09-11 |
United States Patent
Application |
20140252769 |
Kind Code |
A1 |
MENHEERE; David ; et
al. |
September 11, 2014 |
GAS TURBINE ENGINE WITH INTERNAL ELECTROMECHANICAL DEVICE
Abstract
A gas turbine engine including high and low pressure shafts, an
electromechanical device having a rotor and a stator coupled such
that the rotor is rotatable with respect to the stator, the rotor
having a device gear secured thereto, the device being secured to a
support structure in a bearing housing forming part of a bearing
assembly supporting a portion of the low pressure shaft extending
in proximity of the high pressure shaft and of the shaft gear, and
a coupling idle gear secured for rotation about a stationary gear
support mounted in the bearing housing, the idle gear being in
toothed engagement with the shaft gear and with the device gear. An
electromechanical device assembly for a gas turbine engine and a
method of operating an electromechanical device are also
provided.
Inventors: |
MENHEERE; David;
(Georgetown, CA) ; ELEFTHERIOU; Andreas;
(Woodbridge, CA) ; KOSTKA; Richard; (Bolton,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PRATT & WHITNEY CANADA CORP. |
Longueuil |
|
CA |
|
|
Assignee: |
PRATT & WHITNEY CANADA
CORP.
Longueuil
CA
|
Family ID: |
51455195 |
Appl. No.: |
13/792739 |
Filed: |
March 11, 2013 |
Current U.S.
Class: |
290/47 ; 29/596;
290/54; 415/124.2 |
Current CPC
Class: |
H02K 7/1823 20130101;
F05D 2220/766 20130101; H02K 15/14 20130101; F02C 7/36 20130101;
Y10T 29/49009 20150115; F02C 7/275 20130101; H02K 23/52
20130101 |
Class at
Publication: |
290/47 ;
415/124.2; 29/596; 290/54 |
International
Class: |
F02C 7/275 20060101
F02C007/275; H02K 23/52 20060101 H02K023/52; H02K 7/18 20060101
H02K007/18; F02C 7/36 20060101 F02C007/36; H02K 15/14 20060101
H02K015/14 |
Claims
1. A gas turbine engine comprising: a rotatable high pressure shaft
in driving engagement with at least one high pressure rotor of the
engine and having a shaft gear secured thereto; a low pressure
shaft in driving engagement with at least one low pressure rotor of
the engine and rotatable independently of the high pressure shaft;
an electromechanical device having a rotor and a stator coupled
such that the rotor is rotatable with respect to the stator, the
rotor having a device gear secured thereto, the device being
secured to a support structure in a bearing housing, the bearing
housing forming part of a bearing assembly supporting a portion of
the low pressure shaft extending in proximity of the high pressure
shaft and of the shaft gear; and a coupling idle gear secured for
rotation about a stationary gear support mounted in the bearing
housing, the idle gear being in toothed engagement with the shaft
gear and with the device gear.
2. The gas turbine engine as defined in claim 1, wherein the shaft
gear, device gear and idle gear are bevel gears.
3. The gas turbine engine as defined in claim 1, wherein the device
is operable as a generator to generate electrical power when the
rotor is rotated.
4. The gas turbine engine as defined in claim 1, wherein the device
is operable as a starter to rotate the rotor when the device is
electrically powered.
5. The gas turbine engine as defined in claim 1, wherein the
portion of the low pressure shaft is supported by first and second
bearing assemblies with the second bearing assembly being located
closer to the high pressure shaft than the first bearing assembly,
the device being secured between the first and second bearing
assemblies.
6. The gas turbine engine as defined in claim 5, wherein the stator
is secured to the support structure of the second bearing assembly
and the rotor is rotationally supported by the support structure of
the second bearing assembly.
7. The gas turbine engine as defined in claim 5, wherein the device
is enclosed in a housing of the first bearing assembly.
8. The gas turbine engine as defined in claim 1, wherein the low
and high pressure shafts are concentric with the low pressure shaft
extending through the high pressure shaft, the portion of the low
pressure shaft supported by the bearing assembly extending beyond
the high pressure shaft.
9. The gas turbine engine as defined in claim 1, wherein the gear
support is connected to the support structure.
10. An electromechanical device assembly for a gas turbine engine,
said assembly comprising: a rotor mounted on a rotor support, the
rotor support having a device gear secured thereto; a stator
mounted on a stator support, the rotor and stator supports being
coupled such that the rotor is rotatable about the stator to
generate at least one of electrical and mechanical power, the
stator support being secured to a bearing support adapted to be
part of a bearing assembly of a low pressure shaft of the engine; a
shaft gear adapted to be secured to a high pressure shaft of said
engine; and a coupling idle gear in toothed engagement with the
device gear and with the shaft gear, the coupling gear being
adapted to be rotationally supported by a stationary gear support
in a bearing housing of the bearing assembly.
11. The assembly as defined in claim 10, wherein the coupling idle
gear is a disc gear having circumferential bevelled gear teeth, the
device gear and the shaft gear also having circumferential bevelled
gear teeth.
12. The assembly as defined in claim 10, wherein the device is
operable as a generator to generate electrical power when the rotor
is rotated.
13. The assembly as defined in claim 10, wherein the device is
operable as a starter to rotate the rotor when the device is
electrically powered.
14. A method of operating an electromechanical device of a gas
turbine engine, the method comprising: mounting the device in a
bearing housing about a low pressure shaft of the engine with a
rotor of said device having a device gear connected thereto;
securing a shaft gear to a high pressure shaft of the engine; and
coupling the device and shaft gears through direct engagement with
a coupling idle gear rotationally supported on a stationary gear
support mounted in the bearing housing.
15. The method as defined in claim 14, wherein the device is
mounted in the bearing housing between first and second bearing
assemblies supporting a portion of the low pressure shaft
protruding from the high pressure shaft.
16. The method as defined in claim 15, wherein the second bearing
assembly is closer to the high pressure shaft than the first
bearing assembly, and mounting the device includes securing the
device to a bearing support of the second bearing assembly.
17. The method as defined in claim 16, wherein mounting the device
further includes enclosing the device in a bearing housing of the
first bearing assembly.
18. The method as defined in claim 14, wherein mounting the device
includes securing a stator of the device to a bearing support of a
bearing assembly supporting the low pressure shaft, securing the
rotor to a rotor support having the device gear integrally formed
therewith, and rotationally mounting the rotor support to the
bearing support for rotational displacement around the low pressure
shaft.
Description
TECHNICAL FIELD
[0001] The application relates generally to gas turbine engines
and, more particularly, to electromechanical devices in such an
engine.
BACKGROUND OF THE ART
[0002] A known method of installing an internal starter/generator
in a gas turbine engine includes attaching the rotating component
of the internal starter/generator cantilevered from the forward end
of the high pressure shaft of the engine. This usually results in
additional rotating weight on the high pressure shaft and as such
may have an adverse effect on the dynamics of the high pressure
shaft. As such, the addition of an internal starter/generator to an
engine not originally designed to accept one may necessitate a
redesign of the high pressure shaft to support the additional loads
associated with the starter/generator, displacement of bearing
supports to accommodate the starter/generator which may require a
redesign of the low pressure shaft, and/or changes in the low
pressure shaft support structure requiring retesting the engine for
blade-off and bird-ingestion, any of which may result in
substantial development costs.
SUMMARY
[0003] In one aspect, there is provided a gas turbine engine
comprising: a rotatable high pressure shaft in driving engagement
with at least one high pressure rotor of the engine and having a
shaft gear secured thereto; a low pressure shaft in driving
engagement with at least one low pressure rotor of the engine and
rotatable independently of the high pressure shaft; an
electromechanical device having a rotor and a stator coupled such
that the rotor is rotatable with respect to the stator, the rotor
having a device gear secured thereto, the device being secured to a
support structure in a bearing housing, the bearing housing forming
part of a bearing assembly supporting a portion of the low pressure
shaft extending in proximity of the high pressure shaft and of the
shaft gear; and a coupling idle gear secured for rotation about a
stationary gear support mounted in the bearing housing, the idle
gear being in toothed engagement with the shaft gear and with the
device gear.
[0004] In another aspect, there is provided an electromechanical
device assembly for a gas turbine engine, said assembly comprising:
a rotor mounted on a rotor support, the rotor support having a
device gear secured thereto; a stator mounted on a stator support,
the rotor and stator supports being coupled such that the rotor is
rotatable about the stator to generate at least one of electrical
and mechanical power, the stator support being secured to a bearing
support adapted to be part of a bearing assembly of a low pressure
shaft of the engine; a shaft gear adapted to be secured to a high
pressure shaft of said engine; and a coupling idle gear in toothed
engagement with the device gear and with the shaft gear, the
coupling gear being adapted to be rotationally supported by a
stationary gear support in a bearing housing of the bearing
assembly.
[0005] In a further aspect, there is provided a method of operating
an electromechanical device of a gas turbine engine, the method
comprising: mounting the device in a bearing housing about a low
pressure shaft of the engine with a rotor of said device having a
device gear connected thereto; securing a shaft gear to a high
pressure shaft of the engine; and coupling the device and shaft
gears through direct engagement with a coupling idle gear
rotationally supported on a stationary gear support mounted in the
bearing housing.
DESCRIPTION OF THE DRAWINGS
[0006] Reference is now made to the accompanying figures in
which:
[0007] FIG. 1 is a schematic cross-sectional view of a gas turbine
engine;
[0008] FIG. 2 is a schematic cross-sectional side view illustrating
a portion of a gas-turbine engine and an internal electromechanical
device in accordance with a particular embodiment;
[0009] FIG. 3 is a schematic cross-sectional view illustrating a
portion of a gas-turbine engine and an internal electromechanical
device in accordance with another particular embodiment;
[0010] FIG. 4 is a schematic cross-sectional view illustrating a
portion of a gas-turbine engine and a step in the assembly of an
internal electromechanical device therein, in accordance with a
particular embodiment; and
[0011] FIG. 5 is a schematic sectional side view showing a low
pressure shaft assembly, illustrating another step in the assembly
of the starter generator in accordance with a particular
embodiment.
DETAILED DESCRIPTION
[0012] FIG. 1 illustrates a gas turbine engine 10 of a type
preferably provided for use in subsonic flight, generally
comprising in serial flow communication a fan 12 through which
ambient air is propelled, a compressor section 14 for pressurizing
the air, a combustor 16 in which the compressed air is mixed with
fuel and ignited for generating an annular stream of hot combustion
gases, and a turbine section 18 for extracting energy from the
combustion gases. A high pressure shaft 19 drivingly interconnects
high pressure rotors of the compressor and turbine sections 14, 18.
A low pressure shaft 20 rotatable independently from the high
pressure shaft 19 drivingly interconnects the fan 12 and low
pressure rotor(s) of the turbine section 18. Although not shown,
the low pressure shaft 20 may also support additional low pressure
rotor(s) of the compressor section 14. The low pressure shaft 20 is
hollow and extends through the high pressure shaft 19 beyond each
end thereof. Although the engine 10 is illustrated as a turbofan
engine, alternately the engine may be any other adequate type of
gas turbine engine, such as for example a turboprop or a turboshaft
engine.
[0013] Referring to FIG. 2, the portion of the low pressure shaft
20 protruding from the high pressure shaft 19 is supported by first
and second spaced apart bearing assemblies 42, 50 each received in
a respective beating cavity 33, 29, the first bearing assembly 42
being located closer to the end of the low pressure shaft 20, and
as such further from the high pressure shaft 19, than the second
bearing assembly 50. An electromechanical device 21 is described
herein and is installed between the two spaced apart bearing
assemblies 50, 42 about the low pressure shaft 20 to be driven by
the high pressure shaft 19. In a particular embodiment, the
electromechanical device is a starter/generator. The
electromechanical device 21 is an internal device as it is received
radially inwardly with respect to the flowpath of the engine. In a
particular embodiment, the internal electromechanical device 21 is
received within one or more bearing housings.
[0014] Referring to FIG. 2, there is shown the manner in which the
device 21 is supported about the low pressure shaft 20. As herein
shown, the device 21 is provided with a stator 22 and a rotational
rotor 23 which is rotatable about the stator 22. The stator 22 is
housed in a stationary stator support 24 which is secured to a
bearing support 25' of the second bearing assembly 50. The rotor 23
is secured to an arm of a rotor support 25. A ring gear 25'' is
secured to an arm of the rotor support 25. The device gear 25'' has
a series of circumferential teeth 32. A ring gear 26 is further
secured about the end of the high pressure shaft 19 and rotated
therewith. The shaft gear 26 has a series of bevelled gear teeth 27
thereabout.
[0015] In order to transfer the drive between the shaft gear 26 and
the device gear 25'' to produce electricity by the device 21 when
in a generator mode and/or to use the device 21 to drive the high
pressure shaft 19 when in a starter mode, these gears have to be
coupled. In the embodiment shown, this is achieved by mounting a
coupling idle gear 28 in the bearing cavity 29 associated with the
second bearing assembly 50. The coupling idle gear 28 has
circumferential teeth gear 31 which are in toothed engagement with
the bevel gear teeth 27 of the shaft gear 26 and the bevel gear
teeth 32 of the device gear 25''. As herein shown, the coupling
idle gear 28 has a hub 40 which is configured for rotational
displacement in a support assembly 30 secured to stationary
components of bearing support 25'. When the high pressure shaft 19
is rotated, it will cause rotation of the coupling idle gear 28
which in turn rotates the device gear 25'' thereby displacing the
rotor support 25 and the rotor 23 about the stator 22 of the device
to produce electricity. Additionally or alternately, when the rotor
23 is rotated as the device 21 is powered, the device gear 25''
rotates the idle gear 28 which in turn rotates the high pressure
shaft 19 through the shaft gear 26. It is pointed out that the
rotating components of the device 21 are fully supported
independent of other rotating engine components by the same
structure as the bearing support 25' associated with the second
bearing assembly 50. In a particular embodiment, replacement of an
external starter/generator driven by a power shaft by the device 21
driven by the intermediate coupling idle gear 28 supported in the
bearing cavity 29 allows for the bearing support 25' to remain at
the same location so that the shaft dynamics of the low pressure
shaft 20 may be maintained, and so that the dynamics of the high
pressure shaft 19 may be unaffected by the device installation.
[0016] In summary, the method of operating the device 21 generally
comprises the steps of mounting the electromechanical device 21
about the low pressure shaft 20 of a gas turbine engine with the
rotor 23 of the device 21 mounted on the rotor support 25, having
the device gear 25'' secured thereto, and supported about the low
pressure shaft 20 by the bearing support 25'. The method further
comprises securing the shaft gear 26 about the high pressure shaft
19. Still further, the method comprises coupling the shaft gear 26
to the device gear 25'' through the coupling idle gear 28
rotationally supported by a stationary gear support immovably
mounted in the bearing cavity 29.
[0017] It can be appreciated that the ratio between the number of
the bevelled gear teeth of the shaft gear 26, the coupling idle
gear 28 and the device gear 25'' determines the rotational speed of
the rotor 23 in relation to the high pressure shaft speed.
Accordingly, the rotor drive speed can be stepped up or down.
[0018] Referring to FIG. 3, there is shown a further embodiment of
a gear coupling ratio between the high pressure shaft 19 and the
device gear 25'', allowing for a step- up speed relationship. As
herein shown, a shaft ring gear 35 has a conical section 45
rearwardly projecting in the bearing cavity 29. Circumferential
teeth 46 are disposed about the larger outer periphery of the
conical section 45 and are in toothed engagement with the teeth 31'
of a smaller coupling idle gear 28'. The teeth 31' of the coupling
idle gear 28' are also in toothed engagement with the teeth 32 of
the device gear 25''. Accordingly, it can be seen that by modifying
the size of the shaft gears 26, 35 and the coupling idle gear 28,
28' that the relative rotational speed of the rotor 23 with respect
to that of the high pressure shaft 19 can be modified.
[0019] Referring now to FIGS. 4 and 5, there will be described the
method of assembling the device 21 in a gas turbine engine and
about the low pressure shaft 20 thereof and between bearing
assemblies 42, 50.
[0020] The method comprises mounting the rotational rotor 23 of the
device 21 on the rotor support 25 which is provided with the device
gear 25''. The bearings 47 of the rotor support 25 are installed on
a support sleeve 48 of the rotor support 25. The stator 22 of the
device 21 is secured to the stator support 24. The rotor support 25
of the rotor 23 is coupled to a stator housing 49 to rotate about
the stator housing with the stator 22 immovably supported therein.
The stator support 24 is then secured to the bearing support 25' of
the second bearing assembly 50. The second bearing assembly 50 is
then secured, herein by press-fitting it on the low pressure shaft
20. The stator support 24 and the rotor support 25 of the rotor 23
coupled for rotation thereabout are then installed over the bearing
assembly 50 to form a low pressure shaft assembly as shown in FIG.
5.
[0021] As shown in FIG. 4, the bearing support 25' is provided with
an annular flange 51 which is fitted over the second bearing
assembly 50 and the bearings 47 supported on the support sleeve 48
of the rotor support 25 are retained in position by a ledge on the
surface of the flange 51. This secures the bearings and the support
sleeve 48 captive but rotatable on its bearing support.
Accordingly, the internal stator generator with its connection to
the bearing support 25' is now mounted on the low pressure shaft
20, as shown in FIG. 5.
[0022] As shown in FIG. 4, the bearing support 25' is also provided
with a connecting portion 52 having a flange 52' which is immovably
connected to a flange 54' of the bearing housing 54 by a series of
bolts 53 thereabout. The bearing housing 55 of the first bearing
assembly 42 is also provided with a flange 55' which is
interconnectable with the flanges 52' and 54' of the second bearing
housing 54 and the connecting portion 52 for connection therewith.
This is done by different bolts after the flanges 52' and 54' are
interconnected.
[0023] Before the first bearing housing 55 is secured over the
device 21, the power cable 56 are routed from inside the second
bearing housing 54 through the bearing support 25' and over the
stator support 24. The power cable 56 is then secured to cable
connectors 57 mounted exteriorly on the front end of the stator
support 24. The device gear 25'' may be coupled to the coupling
idle gear 28 during the mounting of the bearing support 25' over
the bearings or thereafter. The method therefore also driveably
engaging the high pressure shaft 19 and the rotor 23 of the device
21 and in the particular embodiment shown this includes by securing
the shaft gear 26 to the high pressure shaft 19, rotationally
installing the idle gear 28 on a support 30 in the second bearing
cavity 29 or attached to a gear support 60 securable or integrally
formed on the outer face of the bearing support 25' of the second
bearing assembly 50, and meshing the idle gear 28 with the shaft
gear 26 and the device gear 25'', as shown in FIG. 3.
[0024] In a particular embodiment the idle gear 28 is engaged with
the device gear 25'' and assembled with the low pressure shaft
assembly (including the device 21 and the bearing support 25'). The
shaft gear 26 is assembled to the high pressure shaft 19 before the
installation of the low pressure shaft assembly to the second
bearing housing 54. Assembly of the low pressure shaft assembly to
the second bearing housing 54 engages the teeth of the idle gear 28
and of the shaft gear 26.
[0025] In an alternate embodiment, the idle gear 28, 28' may be
replaced by any other adequate type of member allowing a driving
engagement, including but not limited to a lay shaft.
[0026] The above description is meant to be exemplary only, and one
skilled in the art will recognize that changes may be made to the
embodiments described without departing from the scope of the
invention disclosed. For example, by modifying the gear ratios, a
desired rotor drive speed can be obtained and modified. Still other
modifications which fall within the scope of the present invention
will be apparent to those skilled in the art, in light of a review
of this disclosure, and such modifications are intended to fall
within the appended claims.
* * * * *