U.S. patent application number 17/156933 was filed with the patent office on 2021-12-16 for hybrid power plant for aircraft.
The applicant listed for this patent is PRATT & WHITNEY CANADA CORP.. Invention is credited to Richard FREER, Eric LATULIPE, Jonatan TREMBLAY, Herve TURCOTTE, Patrick VALOIS.
Application Number | 20210388733 17/156933 |
Document ID | / |
Family ID | 1000005355720 |
Filed Date | 2021-12-16 |
United States Patent
Application |
20210388733 |
Kind Code |
A1 |
VALOIS; Patrick ; et
al. |
December 16, 2021 |
HYBRID POWER PLANT FOR AIRCRAFT
Abstract
An hybrid aircraft power plant, has: a gas turbine engine having
a high-pressure spool including a high-pressure compressor, a
high-pressure turbine, and a high-pressure shaft drivingly engaging
the high-pressure turbine to the high-pressure compressor, a
low-pressure spool including a low-pressure compressor, a
low-pressure turbine, and a low-pressure shaft drivingly engaging
the low-pressure turbine to the low-pressure compressor; an
electric motor drivingly engaged to the low-pressure shaft; and a
torque-transmitting device operatively connected to the HP-shaft
and having an engaged configuration in which the
torque-transmitting device drivingly engages the electric motor to
the high-pressure shaft and a disengaged configuration in which the
torque-transmitting device disconnects the electric motor from the
high-pressure shaft.
Inventors: |
VALOIS; Patrick; (Longueuil,
CA) ; TURCOTTE; Herve; (Sainte-Julie, CA) ;
FREER; Richard; (Saint-Basile-Le-Grand, CA) ;
TREMBLAY; Jonatan; (Longueuil, CA) ; LATULIPE;
Eric; (Sainte-Julie, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PRATT & WHITNEY CANADA CORP. |
Longueuil |
|
CA |
|
|
Family ID: |
1000005355720 |
Appl. No.: |
17/156933 |
Filed: |
January 25, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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16901383 |
Jun 15, 2020 |
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17156933 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02C 3/073 20130101;
F01D 15/10 20130101; F01D 15/12 20130101 |
International
Class: |
F01D 15/10 20060101
F01D015/10; F01D 15/12 20060101 F01D015/12; F02C 3/073 20060101
F02C003/073 |
Claims
1. An hybrid aircraft power plant, comprising: a gas turbine engine
having a high-pressure spool including a high-pressure compressor,
a high-pressure turbine, and a high-pressure shaft drivingly
engaging the high-pressure turbine to the high-pressure compressor,
a low-pressure spool including a low-pressure compressor, a
low-pressure turbine, and a low-pressure shaft drivingly engaging
the low-pressure turbine to the low-pressure compressor; an
electric motor drivingly engaged to the low-pressure shaft; and a
torque-transmitting device operatively connected to the HP-shaft
and having an engaged configuration in which the
torque-transmitting device drivingly engages the electric motor to
the high-pressure shaft and a disengaged configuration in which the
torque-transmitting device disconnects the electric motor from the
high-pressure shaft.
2. The hybrid aircraft power plant of claim 1, comprising a
transmission including the torque-transmitting device, the
transmission having an input drivingly engaged by the electric
motor, a first output drivingly engageable to the low-pressure
shaft, and a second output drivingly engageable to the
high-pressure shaft, the transmission operable in a first
configuration in which the electric motor is drivingly engaged to
the high-pressure shaft through the transmission and in a second
configuration in which the electric motor is disengaged from the
high-pressure shaft.
3. The hybrid aircraft power plant of claim 2, wherein the
torque-transmitting device is a clutch, the engaged configuration
corresponding to the first configuration of the transmission and
the disengaged configuration corresponding to the second
configuration of the transmission.
4. The hybrid aircraft power plant of claim 3, wherein the clutch
is a sprag clutch, the sprag clutch transmitting a torque from the
electric motor to the high-pressure shaft when the electric motor
rotates at a higher rotational speed than that of the high-pressure
shaft.
5. The hybrid aircraft power plant of claim 3, wherein the electric
motor is drivingly engaged to the low-pressure shaft in both of the
first configuration and the second configuration of the
transmission.
6. The hybrid aircraft power plant of claim 2, wherein the
transmission is further operable in a third configuration in which
the electric motor is drivingly engaged to the low-pressure shaft
through the transmission and in a fourth configuration in which the
low-pressure shaft is disengaged from the electric motor.
7. The hybrid aircraft power plant of claim 6, wherein the
transmission includes a second clutch between the electric motor
and the low-pressure shaft, the second clutch having an engaged
configuration corresponding to the third configuration of the
transmission and a disengaged configuration corresponding to the
fourth configuration of the transmission.
8. The hybrid aircraft power plant of claim 1, wherein the
torque-transmitting device is a continuously variable transmission
(CVT) having a CVT input drivingly engaged by the electric motor
and a CVT output drivingly engaging the high-pressure shaft, the
CVT operable to control a torque transmitted from the electric
motor to the high-pressure shaft.
9. The hybrid aircraft power plant of claim 8, comprising a second
CVT having a second CVT input drivingly engaged by the electric
motor and a second CVT output drivingly engaging the low-pressure
shaft, the second CVT operable to control a torque transmitted from
the electric motor to the low-pressure shaft.
10. The hybrid aircraft power plant of claim 1, wherein the
torque-transmitting device is a gear assembly having a master gear
drivingly engaged to the electric motor, a first slave gear
drivingly engaged to the high-pressure shaft, and a second slave
gear drivingly engaged to the low-pressure shaft, the master gear
is movable in a first position in which the master gear is meshed
with the first slave gear and disengaged from the second slave
gear, the master gear is movable in a second position in which the
master gear is meshed with the second slave gear and disengaged
from the first slave gear, the master gear is movable in a neutral
position in which the master gear and the electric motor are
disengaged from both of the first slave gear and the second slave
gear and disengaged from both of low-pressure shaft and the
high-pressure shaft.
11. The hybrid aircraft power plant of claim 1, wherein the
electric motor is drivingly engaged to the low-pressure shaft, the
torque-transmitting device being a sprag clutch operatively
connected to both of the high-pressure shaft and the low-pressure
shaft, the sprag clutch operable to transmit a torque from the
low-pressure shaft to the high-pressure shaft when a rotational
speed of the low-pressure shaft is greater than that of the
high-pressure shaft.
12. A method of starting a hybrid aircraft power plant including a
gas turbine engine and an electric motor drivingly engaged to an
electric motor, comprising: drivingly engaging the electric motor
to a high-pressure spool of the gas turbine engine; increasing a
rotational speed of the high-pressure spool to a target rotational
speed; igniting a mixture of air and fuel into a combustor of the
gas turbine engine when the rotational speed of the high-pressure
spool is at the target rotational speed; and transmitting a torque
between a low-pressure spool of the gas turbine engine and the
electric motor.
13. The method of claim 12, comprising disengaging the electric
motor from the high-pressure spool after the igniting of the
mixture of the air and the fuel in to the combustor.
14. The method of claim 12, wherein the drivingly engaging of the
electric motor to the high-pressure spool includes switching a
clutch from a disengaged configuration to an engaged configuration
or includes operating a continuously variable transmission in a
torque transmission mode.
15. The method of claim 12, wherein the drivingly engaging of the
electric motor to the high-pressure spool includes driving the
low-pressure spool with the electric motor and transmitting a
torque from the low-pressure shaft to the high-pressure shaft via a
sprag clutch.
16. The method of claim 12, wherein the drivingly engaging of the
electric motor to the high-pressure spool includes meshing a master
gear drivingly engaged to the electric motor with a first slave
gear drivingly engaged to the high-pressure spool, and wherein the
transmitting of the torque between the electric motor and the
low-pressure spool includes disengaging the master gear from the
first slave gear and meshing the master gear to a second slave gear
drivingly engaged to the low-pressure spool.
17. The method of claim 12, wherein the transmitting of the torque
between the electric motor and the low-pressure spool of the gas
turbine engine includes switching a clutch from a disengaged
configuration to an engaged configuration or includes operating a
continuously variable transmission in a torque transmission
mode.
18. An hybrid aircraft power plant, comprising: a gas turbine
engine having a high-pressure spool including a high-pressure
compressor, a high-pressure turbine, and a high-pressure shaft
drivingly engaging the high-pressure turbine to the high-pressure
compressor, a low-pressure spool including a low-pressure
compressor, a low-pressure turbine, and a low-pressure shaft
drivingly engaging the low-pressure turbine to the low-pressure
compressor; an electric motor drivingly engaged to an electric
motor, the electric motor drivingly engaged to the low-pressure
shaft; and means for selectively drivingly engaging the electric
motor to the high-pressure shaft.
19. The hybrid aircraft power plant of claim 18, wherein the means
are able to engage the electric motor to both of the high-pressure
shaft and to the low-pressure shaft simultaneously.
20. The hybrid aircraft power plant of claim 18, wherein the means
are able to drivingly engage the electric motor to the low-pressure
shaft while disengaging the electric motor from the high-pressure
shaft.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 16/901,383 filed Jun. 15, 2020, the entire
contents of which are incorporated by reference.
TECHNICAL FIELD
[0002] The application relates generally to hybrid power plants for
aircrafts including a gas turbine engine and an electric motor.
BACKGROUND OF THE ART
[0003] Hybrid electric aircraft propulsion systems combine
combustion and electric propulsion technologies. In an electric
propulsion system, electrical energy is converted to mechanical
energy by an electric motor to drive a rotor, such as a prolusion
fan or a propeller. There are environmental and cost benefits to
having at least a portion of the power for an aircraft propulsion
system to come from electric motors.
SUMMARY
[0004] In one aspect, there is provided an hybrid aircraft power
plant, comprising: a gas turbine engine having a high-pressure
spool including a high-pressure compressor, a high-pressure
turbine, and a high-pressure shaft drivingly engaging the
high-pressure turbine to the high-pressure compressor, a
low-pressure spool including a low-pressure compressor, a
low-pressure turbine, and a low-pressure shaft drivingly engaging
the low-pressure turbine to the low-pressure compressor; an
electric motor drivingly engaged to the low-pressure shaft; and a
torque-transmitting device operatively connected to the HP-shaft
and having an engaged configuration in which the
torque-transmitting device drivingly engages the electric motor to
the high-pressure shaft and a disengaged configuration in which the
torque-transmitting device disconnects the electric motor from the
high-pressure shaft.
[0005] In some embodiments, the hybrid aircraft power plant
includes a transmission including the torque-transmitting device,
the transmission having an input drivingly engaged by the electric
motor, a first output drivingly engageable to the low-pressure
shaft, and a second output drivingly engageable to the
high-pressure shaft, the transmission operable in a first
configuration in which the electric motor is drivingly engaged to
the high-pressure shaft through the transmission and in a second
configuration in which the electric motor is disengaged from the
high-pressure shaft.
[0006] In some embodiments, the torque-transmitting device is a
clutch, the engaged configuration corresponding to the first
configuration of the transmission and the disengaged configuration
corresponding to the second configuration of the transmission.
[0007] In some embodiments, the clutch is a sprag clutch, the sprag
clutch transmitting a torque from the electric motor to the
high-pressure shaft when the electric motor rotates at a higher
rotational speed than that of the high-pressure shaft.
[0008] In some embodiments, the electric motor is drivingly engaged
to the low-pressure shaft in both of the first configuration and
the second configuration of the transmission.
[0009] In some embodiments, the transmission is further operable in
a third configuration in which the electric motor is drivingly
engaged to the low-pressure shaft through the transmission and in a
fourth configuration in which the low-pressure shaft is disengaged
from the electric motor.
[0010] In some embodiments, the transmission includes a second
clutch between the electric motor and the low-pressure shaft, the
second clutch having an engaged configuration corresponding to the
third configuration of the transmission and a disengaged
configuration corresponding to the fourth configuration of the
transmission.
[0011] In some embodiments, the torque-transmitting device is a
continuously variable transmission (CVT) having a CVT input
drivingly engaged by the electric motor and a CVT output drivingly
engaging the high-pressure shaft, the CVT operable to control a
torque transmitted from the electric motor to the high-pressure
shaft.
[0012] In some embodiments, the power plant includes a second CVT
having a second CVT input drivingly engaged by the electric motor
and a second CVT output drivingly engaging the low-pressure shaft,
the second CVT operable to control a torque transmitted from the
electric motor to the low-pressure shaft.
[0013] In some embodiments, the torque-transmitting device is a
gear assembly having a master gear drivingly engaged to the
electric motor, a first slave gear drivingly engaged to the
high-pressure shaft, and a second slave gear drivingly engaged to
the low-pressure shaft, the master gear is movable in a first
position in which the master gear is meshed with the first slave
gear and disengaged from the second slave gear, the master gear is
movable in a second position in which the master gear is meshed
with the second slave gear and disengaged from the first slave
gear, the master gear is movable in a neutral position in which the
master gear and the electric motor are disengaged from both of the
first slave gear and the second slave gear and disengaged from both
of low-pressure shaft and the high-pressure shaft.
[0014] In some embodiments, the electric motor is drivingly engaged
to the low-pressure shaft, the torque-transmitting device being a
sprag clutch operatively connected to both of the high-pressure
shaft and the low-pressure shaft, the sprag clutch operable to
transmit a torque from the low-pressure shaft to the high-pressure
shaft when a rotational speed of the low-pressure shaft is greater
than that of the high-pressure shaft.
[0015] In another aspect, there is provided a method of starting a
hybrid aircraft power plant including a gas turbine engine and an
electric motor drivingly engaged to an electric motor, comprising:
drivingly engaging the electric motor to a high-pressure spool of
the gas turbine engine; increasing a rotational speed of the
high-pressure spool to a target rotational speed; igniting a
mixture of air and fuel into a combustor of the gas turbine engine
when the rotational speed of the high-pressure spool is at the
target rotational speed; and transmitting a torque between a
low-pressure spool of the gas turbine engine and the electric
motor.
[0016] In some embodiments, the electric motor is disengaged from
the high-pressure spool after the igniting of the mixture of the
air and the fuel in to the combustor.
[0017] In some embodiments, the drivingly engaging of the electric
motor to the high-pressure spool includes switching a clutch from a
disengaged configuration to an engaged configuration or includes
operating a continuously variable transmission in a torque
transmission mode.
[0018] In some embodiments, the drivingly engaging of the electric
motor to the high-pressure spool includes driving the low-pressure
spool with the electric motor and transmitting a torque from the
low-pressure shaft to the high-pressure shaft via a sprag
clutch.
[0019] In some embodiments, the drivingly engaging of the electric
motor to the high-pressure spool includes meshing a master gear
drivingly engaged to the electric motor with a first slave gear
drivingly engaged to the high-pressure spool, and wherein the
transmitting of the torque between the electric motor and the
low-pressure spool includes disengaging the master gear from the
first slave gear and meshing the master gear to a second slave gear
drivingly engaged to the low-pressure spool.
[0020] In some embodiments, the transmitting of the torque between
the electric motor and the low-pressure spool of the gas turbine
engine includes switching a clutch from a disengaged configuration
to an engaged configuration or includes operating a continuously
variable transmission in a torque transmission mode.
[0021] In yet another aspect, there is provided an hybrid aircraft
power plant, comprising: a gas turbine engine having a
high-pressure spool including a high-pressure compressor, a
high-pressure turbine, and a high-pressure shaft drivingly engaging
the high-pressure turbine to the high-pressure compressor, a
low-pressure spool including a low-pressure compressor, a
low-pressure turbine, and a low-pressure shaft drivingly engaging
the low-pressure turbine to the low-pressure compressor; an
electric motor drivingly engaged to an electric motor, the electric
motor drivingly engaged to the low-pressure shaft; and means for
selectively drivingly engaging the electric motor to the
high-pressure shaft.
[0022] In some embodiments, the means are able to engage the
electric motor to both of the high-pressure shaft and to the
low-pressure shaft simultaneously.
[0023] In some embodiments, the means are able to drivingly engage
the electric motor to the low-pressure shaft while disengaging the
electric motor from the high-pressure shaft.
DESCRIPTION OF THE DRAWINGS
[0024] Reference is now made to the accompanying figures in
which:
[0025] FIG. 1 is a schematic side cross sectional view of an hybrid
aircraft power plant including a turboprop gas turbine engine, an
electric module, and a transmission in accordance with one
embodiment for engaging the electric module to the turboprop gas
turbine engine;
[0026] FIG. 2 is a schematic side cross sectional view of an hybrid
aircraft power plant including a turboshaft gas turbine engine
equipped with the electric module and transmission of FIG. 1;
[0027] FIG. 3 is a schematic side cross sectional view of a first
exemplary embodiment of the transmission depicted in FIGS. 1 and
2;
[0028] FIG. 4 is a schematic side cross sectional view of a second
exemplary embodiment of a transmission to couple the electric
module to the turboprop or turboshaft gas turbine engines of FIGS.
1 and 2;
[0029] FIG. 5 is a schematic side cross sectional view of a third
exemplary embodiment of a transmission to couple the electric
module to the turboprop or turboshaft gas turbine engines of FIGS.
1 and 2;
[0030] FIG. 6 is a schematic side cross sectional view of a fourth
exemplary embodiment of a transmission to couple the electric
module to the turboprop or turboshaft gas turbine engines of FIGS.
1 and 2;
[0031] FIG. 7 is a schematic side cross sectional view of a fifth
exemplary embodiment of a transmission to couple the electric
module to the turboprop or turboshaft gas turbine engines of FIGS.
1 and 2;
[0032] FIG. 8 is a schematic side cross sectional view of a sixth
exemplary embodiment of a transmission to couple the electric
module to the turboprop or turboshaft gas turbine engines of FIGS.
1 and 2;
[0033] FIG. 9 is a schematic side cross sectional view of a seventh
exemplary embodiment of a transmission to couple the electric
module to the turboprop or turboshaft gas turbine engines of FIGS.
1 and 2;
[0034] FIG. 10 is a schematic side cross sectional view of an
hybrid aircraft power plant in accordance with another embodiment
including a turboprop gas turbine engine and an electric
module;
[0035] FIG. 11 is a schematic side cross sectional view of an
hybrid aircraft power plant in accordance with yet another
embodiment including a turboshaft gas turbine engine equipped with
an electric module; and
[0036] FIG. 12 is a schematic view of a control system for
controlling an interaction between the electric module and the
turboprop or turboshaft gas turbine engines of FIGS. 1 and 2.
DETAILED DESCRIPTION
[0037] In at least some of the figures that follow, some elements
appear more than once (e.g. there may be two, three, etc. of a
given part in a given embodiment). Accordingly, only a first
instance of each given element may be labeled, to maintain clarity
of the figures.
[0038] Referring to FIG. 1, an hybrid aircraft power plant is shown
at 10. The hybrid aircraft power plant 10 is referred to herein
below simply as "power plant 10" for the sake of conciseness. The
power plant 10 includes a thermal module depicted here as a gas
turbine engine 11. The gas turbine engine 11 is shown in FIG. 1 as
being a turboprop gas turbine engine drivingly engaged to a
propeller 12 via a reduction gearbox 14.
[0039] The gas turbine engine 11 includes an inlet 21 at a rear of
the gas turbine engine 11 relative to a direction of travel T of
the power plant 10. The gas turbine engine 11 includes an exhaust
22 at a front of the power plant 10 relative to the direction of
travel T. The gas turbine engine 11 is therefore a reverse-flow
engine in that air flows from the inlet 21 to the exhaust 22 in an
annular gas path 23 from the rear to the front in the same
direction as the direction of travel T.
[0040] The gas turbine engine 11 includes a low-pressure (LP) spool
24 and a high-pressure (HP) spool 25. The term "spool" is herein
intended to broadly refer to drivingly connected turbine and
compressor rotors and is, thus, not limited to a compressor and
turbine assembly on a single shaft. It also includes a rotary
assembly with multiple shafts geared together. The LP spool 24
includes a LP compressor 24a, a LP or power turbine 24b, and a LP
shaft 24c drivingly engaging the LP turbine 24b to the LP
compressor 24a. The HP spool 25 includes a HP compressor 25a, a HP
turbine 25b, and a HP shaft 25c drivingly engaging the HP turbine
25b to the HP compressor 25a. The gas turbine engine 11 includes a
combustor 26 between the HP turbine 25b and the HP compressor 25a.
In the embodiment shown, the HP shaft 25c is hollow and the LP
shaft 24c extends within the HP shaft 25c. Other configurations are
contemplated.
[0041] Air enters the gas turbine engine 11 via the inlet 21 and
flows into the annular gas path 23 through the LP compressor 24a
and through the HP compressor 25a located downstream of the LP
compressor 24a relative to a direction of the flow into the annular
gas path 23. The air, now compressed, is mixed with fuel into the
combustor 26 and is ignited thereby generating combustion gases.
The combustion gases flow out of the combustor 26 into the HP
turbine 25b, which extracts energy from the combustion gases to
drive the HP compressor 25a via the HP shaft 25c. The combustion
gases then flow through the LP or power turbine 24b located
downstream of the HP turbine 25b relative to the direction of the
flow through the annular gas path 23. The LP turbine 24b extracts
power from the combustion gases to drive the LP compressor 24a via
the LP shaft 24c. The LP turbine 24b further drivingly engages the
propeller 12 via the reduction gearbox 14. The reduction gearbox 14
drives the propeller 12 via an output shaft 27.
[0042] In some cases, it might be required to provide a boost of
power to the gas turbine engine 11 and/or to help starting the gas
turbine engine 11. The power plant 10 further includes an electric
module 30 configured for compounding power with the gas turbine
engine 11 in driving the propeller 12. The electric module 30 may
be engaged to the LP spool 24 and/or to the HP spool 25. In the
embodiment shown, a transmission 40 acts as an interface between
the electric module 30 and the LP and HP spools 24, 25. The
transmission 40 is secured to the rear of the turboprop gas turbine
engine 11. The electric module 30 is drivingly engaged to the gas
turbine engine 11 via the transmission 40. In the present
disclosure, the expression "electric module" may include one or
more electric motor(s) 32 drivingly engaged to a single shaft 31.
That is, the electric module 30 may include a plurality of electric
motors, disposed in series or in parallel, that compound their
power to drive the single shaft 31.
[0043] The transmission 40 is used to drivingly engage the electric
module 30 to the LP shaft 24c alone, to the HP shaft 25c alone,
and/or to both of the LP and HP shafts 24c, 25c. The transmission
40 may include clutches to selective engage or disengage the
electric module 30 from the LP and HP shafts 24c, 25c. The
transmission 40 may include a gearbox to divide a rotational input
received from the electric module 30 between the LP and HP shafts
24c, 25c. Many possible embodiments of the transmission are
described below.
[0044] In the embodiment shown, a series of intermediary shafts 49
are used to connect the transmission 40 to the HP shaft 25c. It
will be understood that any suitable connection may be used to
drivingly engage the transmission 40 to the HP shaft 25. The
intermediary shafts 49 may be drivingly engaged to one another
using bevel gears, universal joints, or any other suitable means.
One of the intermediary shafts 49 is located radially outside the
annular gas path 23 relative to an axis of rotation of the HP and
LP shafts 25c, 24c. Although said intermediary shafts 49 are shown
as being connected at a rear of the HP shaft 25c, they may
alternatively be connected at a front thereof.
[0045] Referring now to FIG. 2, a hybrid aircraft power plant is
shown at 110. The power plant 110 includes a gas turbine engine
111. The gas turbine engine 111 is shown in FIG. 2 as being a
turboshaft gas turbine engine drivingly engaged to an output shaft
112. The output shaft 112 may be engaged to any rotatable load such
as, for instance, a helicopter rotor. The power plant 110 includes
a thermal module corresponding to the gas turbine engine 111. The
power plant 110 includes the electric module 30 configured for
compounding power with the gas turbine engine 111 in driving the
output shaft 112.
[0046] The gas turbine engine 111 includes an inlet 121 at a front
of the gas turbine engine 111 relative to the direction of travel T
of the power plant 110. The gas turbine engine 111 includes an
exhaust 122 at a rear of the power plant 110 relative to the
direction of travel T. The gas turbine engine 111 is therefore a
through-flow engine in that air flows from the inlet 121 to the
exhaust 122 in an annular gas path 123 from the front to the rear
in an opposite direction as the direction of travel T.
[0047] The gas turbine engine 111 includes a low-pressure (LP)
spool and a high-pressure (HP) spool. The LP spool includes a LP
compressor 124a, a LP or power turbine 124b, and a LP shaft 124c
drivingly engaging the LP turbine 124b of the LP compressor 124a.
The HP spool includes a HP compressor 125a, a HP turbine 125b, and
a HP shaft 125c drivingly engaging the HP turbine 125b to the HP
compressor 125a. The gas turbine engine 111 includes a combustor
126 between the HP turbine 125b and the HP compressor 125a. In the
embodiment shown, the HP shaft 125c is hollow and the LP shaft 124c
extends within the HP shaft 125c. Other configurations are
contemplated.
[0048] Air enters the gas turbine engine 111 via the inlet 121 and
flows into the annular gas path 123 through the LP compressor 124a
and through the HP compressor 125a located downstream of the LP
compressor 124a relative to a direction of the flow into the
annular gas path 123. The air, now compressed, is mixed with fuel
into the combustor 126 and is ignited thereby generating combustion
gases. The combustion gases flow out of the combustor 126 into the
HP turbine 125b, which extracts energy from the combustion gases to
drive the HP compressor 125a via the HP shaft 125c. The combustion
gases then flow through the LP or power turbine 124b located
downstream of the HP turbine 125b relative to the direction of the
flow through the annular gas path 123. The LP turbine 124b extracts
power from the combustion gases to drive the LP compressor 124a via
the LP shaft 124c. The LP turbine 124b further drivingly engages
the output shaft 112 and the rotatable load connected thereto.
[0049] The power plant 110 includes the same electric module 30 and
transmission 40 described herein above with reference to FIG. 1.
The transmission 40 is secured closer to the front of the
turboshaft gas turbine engine 11. In the embodiment shown, the
transmission 40 is drivingly engaged to the LP and HP shafts 124c,
125c via first and second intermediary shafts 149a, 149b,
respectively, that extend generally transverse to the LP and HP
shafts 124c, 125c. Bevel gears may be used to drivingly engage the
two shafts 149a, 149b to the LP and HP shafts 124c, 125c. Other
configurations are contemplated.
[0050] It will be appreciated that the HP shaft 25c, 125c is
selectively drivingly engaged to the electric motor 30 via the
single shaft 31. A torque-transmitting device is used to
selectively engage the single shaft 31 to the HP shaft 25c, 125c.
The torque-transmitting device has an engaged configuration in
which the single shaft 31 is drivingly engaged to the high-pressure
shaft 25c, 125c and a disengaged configuration in which the single
shaft 31 is disengaged from the high-pressure shaft 25c, 125c. The
torque-transmitting device, as will be described below, may be any
suitable means able to selectively drivingly engage the HP shaft
25c, 125c to the electric motor 30. The torque-transmitting device
may be, for instance, a clutch, a sprag clutch, a gear assembly, a
continuously variable transmission (CVT), and so on. Any suitable
types of clutches may be used as explained below. Another
torque-transmitting device may be used to selectively drivingly
engage the LP shaft 24c, 124c to the electric motor 30 as explained
below. The means may be able to engage the electric motor to both
of the high-pressure shaft and to the low-pressure shaft
simultaneously. The means may be able to drivingly engage the
electric motor to the low-pressure shaft while disengaging the
electric motor from the high-pressure shaft.
[0051] Referring now to FIG. 3, the transmission 40 that may be
used with either one of the power plant 10 of FIG. 1 or with the
power plant 110 of FIG. 2 is described in greater detail below. The
transmission 40 is operable in a first configuration in which the
electric motor shaft 31 is drivingly engaged to the low-pressure
shaft 24c, 124c through the transmission 40 and in a second
configuration in which the low-pressure shaft 24c, 124c is
disengaged from the electric motor shaft 31. The transmission is
operable in a third configuration in which the electric motor shaft
31 is drivingly engaged to the high-pressure shaft 25c, 125c
through the transmission 40 and in a fourth configuration in which
the electric motor shaft 31 is disengaged from the high-pressure
shaft 25c, 125c.
[0052] The transmission 40 has an input 41, a first output 42, and
a second output 43. The transmission 40 includes a first clutch 44
and a second clutch 45. The first input 41 is drivingly engaged to
the electric module 30 via the single shaft 31. The first output 42
is drivingly engaged to the LP shaft 24c. The second output 43 is
drivingly engaged to the HP shaft 25c. The expression "clutch" as
used herein encompasses any device able to selectively drivingly
engage two elements with one another. For instance, any suitable
clutch may be used such as, for instance, friction clutch,
centrifugal clutch, dog/spline clutch, hydraulic clutch,
electromagnetic clutch, and so on. Each of the first and second
clutches 44, 45 has an engaged configuration in which the electric
module 30 is drivingly engaged to a respective one of the LP and HP
shafts 24c, 25c and a disengaged configuration in which the
electric module 30 is disengaged from the respective one of the LP
and HP shafts 24c, 25c. The engaged configuration of the first
clutch 44 corresponds to the first configuration of the
transmission 40. The disengaged configuration of the first clutch
44 corresponds to the second configuration of the transmission 40.
The engaged configuration of the second clutch 45 corresponds to
the third configuration of the transmission 40. And, the disengaged
configuration of the second clutch 45 corresponds to the fourth
configuration of the transmission 40.
[0053] In the embodiment of FIG. 3, the transmission 40 contains
two clutches so the state of each clutch at any one time may
determine the configuration of transmission 40. For example, there
may be four configurations possible for transmission 40: both
clutches 44, 45 engaged, both clutches 44, 45 disengaged, first
clutch 44 engaged while second clutch 45 is disengaged, and second
clutch 45 engaged while first clutch 44 is disengaged.
[0054] In the depicted embodiment, the transmission 40 includes a
gear assembly, also referred to as an accessory gearbox (AGB), 50
having a master gear 51 that is drivingly engaged to the single
shaft 31 that connects the electrical module 30 to the transmission
40. The gear assembly may be part of a gearbox that may be used to
drive other accessories, such as pumps, generators, and so on. The
transmission 40 has a first slave gear 52 meshed with the master
gear 51. The first slave gear 52 is drivingly engaged to the first
output 42 of the transmission 40 through the first clutch 44. The
transmission 40 has a second slave gear 53 meshed with the master
gear 51. The second slave gear 53 is drivingly engaged to the
second output 43 of the transmission 40 through the second clutch
45. It will be appreciated that any suitable gear assembly may be
used without departing from the scope of the present disclosure.
For instance, a planetary gear may be used. Alternatively, straps
and pulleys may be used. Any suitable means able to transmit a
rotational input may be used. Although only three gears are
depicted, more than three gears may be used to cater to distances
between the different shafts and/or to provide speed ratios.
[0055] Referring to FIGS. 1-3, the electric module 30 may be used
in a torque configuration or a speed configuration. In the torque
configuration, the electric module 30 compounds power with one or
both of the LP and HP shafts 24c, 25c, 124c, 125c. In the speed
configuration, the electric module 30 may be operated such that no
torque is provided by the electric module 30 to the one or both of
the LP and HP shafts 24c, 25c, 124c, 125c and that no energy is
used by the gas turbine engines 11, 111 to drive the electric motor
30. In other words, in the speed configuration, the electric module
30 is operated to minimize resistance on the LP and HP shafts 24c,
25c, 124c, 125c. In the speed configuration, the electric motor may
also be used to maintain a target spool rotational speed by
providing varying positive or negative torque if so desired.
[0056] The electric module 30 may be used for staring the gas
turbine engines 11, 111. In such a case, the second clutch 45 is
configured in its engaged configuration to drivingly engage the
electric module 30 to the HP shaft 25c via the gear assembly 50 and
the second clutch 45. Rotation of the HP spool is therefore induced
by powering the electric module 30. Once a desired rotational speed
of the HP shaft 25c, 125c is achieved, a mixture of air and fuel
into the combustion chamber 26, 126 may be ignited. The electric
module 30 may continue to drivingly engage the HP shaft 25c, 125c
until its rotational speed corresponds to an idle rotational speed.
Once the idle rotational speed is achieved, a torque target of the
electric module 30 may be set to zero to off-load the transmission
40. In some cases, the electric module 30 may be operated in
generator mode to extract energy from the HP shaft 25c, 125c.
Alternatively, the electric module 30 may be powered to a target
rotational speed to minimize a speed difference across the second
clutch 45. At some point, the second clutch 45 is switched to its
disengaged configuration to disengage the electric module 30 from
the HP shaft 25c, 125c. A rotational speed of the electric module
30 may be varied until a speed difference across the first clutch
44 is minimized. Once this speed matching is achieved, the first
clutch 44 may be switched to its engaged configuration to drivingly
engage the electric module 30 to the LP shaft 24c, 124c through the
gear assembly 50 and the first clutch 44. The electric module 30
may therefore be powered in torque mode to compound power with the
LP shaft 24c, 124c to help the gas turbine engine 11, 111 driving
the propeller 12 or the output shaft 112. In some cases, the
electric module 30 may be operated in generator mode to extract
energy from the LP shaft 24c, 124c to generate electricity. In some
other cases, the electric module 30 may be operated in speed mode
such that the electric module 30 does not provide any torque to the
LP shaft 24c, 124c and does not extract energy from the LP shaft
24c, 124c.
[0057] A plurality of alternative configurations of transmissions
are described herein below with reference to FIGS. 4-9.
[0058] Referring now to FIG. 4, a transmission in accordance with
another embodiment is shown at 140. The transmission 140 described
below with reference to FIG. 4 may be used with any of the
turboprop gas turbine engine 11 of FIG. 1 and with the turboshaft
gas turbine engine 111 of FIG. 2.
[0059] The transmission 140 includes an input 141 drivingly engaged
to the electric module 30 via the single shaft 31. The transmission
140 includes a first output 142 and a second output 143. In the
embodiment shown the first output 142 is permanently drivingly
engaged to the LP shaft 24c, 124c of the gas turbine engine 11,
111. That is, in this embodiment, the electric module 30 is
continuously and always engaged to the LP shaft 24c. The second
output 142 is selectively drivingly engageable to the HP shaft 25c
via the intermediary shafts 49 for the turboprop engine 11 of FIG.
1 and via the second intermediary shaft 149b for the turboshaft
engine 111 of FIG. 2 as explained above. The transmission 140
includes a clutch 145 that selectively engages the electric module
30 to the HP shaft 25c through the gear assembly 50 and the clutch
145. The clutch 145 has a disengaged configuration in which the
electric module 30 is disengaged from the HP shaft 25c, 125c and an
engaged configuration in which the electric module 30 is drivingly
engaged to the HP shaft 25c. 125c.
[0060] The electric module 30 may be operated in a power generation
mode in which the LP shaft 24c, 124c drives the electric module 30
as a generator to generate electricity. The electric module 30 may
be operated in a speed configuration in which a rotational speed of
the electric module 30 is selected to minimize a rotational
resistance on the LP shaft 24c, 124c. The electric module 30 may be
operated in a torque configuration in which the electric module 30
provides torque to compound power with the LP shaft 24c, 124c in
driving the propeller 12 or the output shaft 112.
[0061] Since the electric module 30 is, in the depicted embodiment,
permanently coupled to the LP shaft 24c, 124c, higher engine
starting torque may be required from the electric module 30 since
inertia of the LP spool and of the propeller 12 (FIG. 1) or of the
output shaft 112 (FIG. 2) would be added to that of the HP spool,
but may be a simpler mechanical arrangement. Moreover, less steps
may be required since only one clutch has to be disengaged after
the engine is started. The clutch 145 may be switched to its
disengaged configuration by electronic control, or mechanically
upon reaching a speed or torque threshold.
[0062] Referring now to FIG. 5, another configuration of a
transmission is shown at 240. The transmission 240 includes an
input 241 drivingly engaged to the electric module 30 via the
single shaft 31. The transmission 240 includes a first output 242
and a second output 243. In the embodiment shown, the transmission
240 includes a master pulley 251 that is drivingly engaged to the
input 241 of the transmission 240. The master pulley 251 is
drivingly engaged to a pulley of a first continuously variable
transmission (CVT) 252 and to a pulley of a second CVT 253. The
first CVT 252 is drivingly engaged to the first output 242 of the
transmission 240 and the second CVT 253 is drivingly engaged to the
second output 243 of the transmission 240. In other words, the
electric module 30 is drivingly engageable to the LP shaft 24c,
124c via the first CVT 252. The electric module 30 is drivingly
engageable to the HP shaft 25c, 125c via the second CVT 253. The
expression "CVT" as used herein encompasses any type of
transmission with continuously variable speed ratio between the
input and output. The concept is hereby described and illustrated
for a belt and pulley type of CVT. Alternatively, friction discs or
hydraulic types CVTs may be used.
[0063] The first and second CVTs 252, 253 are operable to vary a
speed ratio between their respective inputs driven by the master
pulley 251 and their respective outputs engaged respectively to the
LP and HP shafts. The first and second CVTs 252, 253 may be
electronically controlled or may be mechanically controlled as a
function of a transmitted torque. In the embodiment shown, the
electric module 30 may be operated in a speed configuration in
which a rotational speed of the electric module 30 is selected to
minimize a rotational resistance on the LP shaft 24c, 124c or HP
shaft 25c, 125c. The electric module 30 may be operated in a torque
configuration in which the electric module 30 provides torque to
compound power with the LP shaft 24c, 124c or HP shaft 25c, 125c.
When starting the engine, the second CVT 253 is configured to be
able to transmit a rotational input from the electric module 30 to
the second output 243 of the transmission 240. When the gas turbine
engine 11, 111 reaches a speed threshold, a speed ratio generated
by the second CVT 253 may be selected to avoid torque transmission
through the second CVT 253. After the engine 11, 111 is started,
the first CVT 252 may be configured to allow the electric module 30
to transfer torque to the LP shaft 24c, 124c. The electric module
30 may also be used in generator mode to extract energy, via the
transmission 240, from the HP shaft 25c, 125c, or from the LP shaft
24c, 124c.
[0064] Referring now to FIG. 6, a transmission in accordance with
another embodiment is shown at 340. The transmission 340 may be
used with either of the power plant 10 of FIG. 1 and with the power
plant 110 of FIG. 2 and is described in greater detail below.
[0065] The transmission 340 has an input 341, a first output 342,
and a second output 343. The transmission 340 includes a first
clutch 344 and a sprag clutch 345. The input 341 is drivingly
engaged to the electric module 30 via the single shaft 31. The
input 341 is selectively drivingly engageable to the LP shaft 24c,
124c via the first clutch 344 and drivingly engageable to the HP
shaft 25c, 125c via the sprag clutch 345.
[0066] The transmission 340 includes the gear assembly 50 described
above with reference to FIG. 3. The sprag clutch 345 allows torque
transmission from the electric module 30 to the HP shaft 25c, 125c
when a rotational speed at an input of the sprag clutch 345 is
greater than that at an output of the sprag clutch 345. Hence, when
starting the engine 11, 111, the HP shaft 25c, 125c is not
rotating. A torque generated by the electric module 30 is
transmitted via the single shaft 31 to the gear assembly 50 and
from the gear assembly 50 to the HP shaft 25c, 125c via the sprag
clutch 345. Once the HP shaft 25c, 125c reaches a rotational speed
threshold, air and fuel in the combustion chamber 26, 126 are
ignited. At some point, a rotational speed of the HP shaft 25c,
125c increases such that a rotational speed at the output of the
sprag clutch 345 is greater than a rotational speed at its input.
The HP shaft 25c, 125c becomes effectively disengaged from the
electric module 30 and the HP shaft 25c, 125c may rotate without
receiving or providing a torque to the electric module 30. In other
words, the HP shaft 25c, 125c becomes disengaged from the electric
module 30 once the HP shaft 25c, 125c reaches a given rotational
speed threshold and, in the present embodiment, when the
intermediary shaft 49 (FIG. 1) and second intermediary shaft 149b
rotate faster than the second slave gear 53.
[0067] After the engine 11, 111 is started, the first clutch 344
may be switched to its engaged configuration and the electric
module 30 may be operated in torque mode such that a torque
generated by the electric module 30 is transmitted to the LP shaft
24c, 124c via the first clutch 344 and the gear assembly 50. In
some cases, the electric module 30 may be operated in generator
mode to extract energy from the LP shaft 24c, 124c.
[0068] Referring now to FIG. 7, a transmission in accordance with
another embodiment is shown at 440. The transmission 440 may be
used with either of the power plant 10 of FIG. 1 and with the power
plant 110 of FIG. 2 and is described in greater detail below.
[0069] In the embodiment shown, the electric module 130 includes an
electric motor 132 in driving engagement with a shaft 131. The
shaft 131 is movable axially about an axis of rotation of the shaft
131 and relative to the electric motor 132 along a direction
depicted by arrow A in FIG. 7. The shaft 131 may be a splined shaft
to allow a sliding motion relative to the electric motor 132. An
actuator 133 is operatively connected to the shaft 131 to move the
shaft along arrow A. The gear assembly 350 includes a master gear
351 that is drivingly engaged to the shaft 131. The master gear 351
is fixedly connected to the shaft 131. The master gear 351 may be
monolithic with the shaft 131. The shaft 131 and the master gear
351 secured thereto are movable between a first position in which
the master gear 351 is meshed with the first slave gear 352 and in
which the electric module 130 is in driving engagement with the LP
shaft 24c, 124c; a second position in which the master gear 351 is
meshed with the second slave gear 353 and in which the electric
module 130 is in driving engagement with the HP shaft 25c, 125c;
and a neutral position depicted in FIG. 7 in which the electric
module 130 is disengaged from both of the LP and HP shafts 24c,
124c, 25c, 125c.
[0070] The actuator 133 is therefore operable to move the shaft 131
along the arrow A to selectively mesh the master gear 351 with
either the first slave gear 352 or with the second slave gear 353
or to dispose the master gear 351 in its neutral position. The
actuator 133 may be a solenoid, a hydraulic actuator, a pneumatic
actuator, or any other suitable actuators.
[0071] Referring now to FIG. 8, a transmission in accordance with
another embodiment is shown at 540. The transmission 540 may be
used with either of the power plant 10 of FIG. 1 and with the power
plant 110 of FIG. 2 and is described in greater detail below.
[0072] In the embodiment shown, the electric module 230 includes an
electric motor 232 in driving engagement with a shaft 231. The
electric motor 232 is received within a housing 234. The housing
234 is secured to an enclosure 454 of the gear assembly 450. The
shaft 231 and the electric motor 232 are axially slidably movable
within the housing 234 along arrow A about an axis of rotation of
the shaft 231. An actuator 233 is operatively connected to the
electric motor 232 to axially move the electric motor 232 and the
shaft 231 along arrow A. The gear assembly 450 includes a master
gear 451 that is drivingly engaged to the shaft 231. The master
gear 451 is fixedly connected to the shaft 231. The master gear 451
may be monolithic with the shaft 231. The electric motor 232, the
shaft 231, and the master gear 451 secured to the shaft 231 are
movable between a first position in which the master gear 451 is
meshed with the first slave gear 452 and in which the electric
module 230 is in driving engagement with the LP shaft 24c, 124c; a
second position in which the master gear 451 is meshed with the
second slave gear 453 and in which the electric module 230 is in
driving engagement with the HP shaft 25c, 125c; and a neutral
position depicted in FIG. 8 and in which the electric module 230 is
disengaged from both of the LP and HP shafts 24c, 124c, 25c,
125c.
[0073] The actuator 233 is therefore operable to move the shaft 231
and the electric motor 232 along the arrow A to selectively mesh
the master gear 451 with either the first slave gear 452 or with
the second slave gear 453 or to dispose the master gear 451 in its
neutral position. The actuator 233 may be a solenoid, a hydraulic
actuator, a pneumatic actuator, or any other suitable
actuators.
[0074] Referring now to FIG. 9, a transmission in accordance with
another embodiment is shown at 640. The transmission 640 may be
used with either of the power plant 10 of FIG. 1 and with the power
plant 110 of FIG. 2 and is described in greater detail below.
[0075] In the embodiment shown, the electric module 330 includes an
electric motor 332 in driving engagement with a shaft 331. The
master gear 551 of the gear assembly 550 is drivingly engaged to
the shaft 331 and is axially slidable relative to the shaft 331
about an axis of rotation of the shaft 331. A spline coupling may
be used between the master gear 551 and the shaft 331. An actuator
333 secured within an enclosure of the gear assembly 550 is
operatively connected to the master gear 551 to axially move the
master gear 551 along the shaft 331.
[0076] The master gear 551 is movable between a first position in
which the master gear 551 is meshed with the first slave gear 552
and in which the electric module 330 is in driving engagement with
the LP shaft 24c, 124c; a second position in which the master gear
551 is meshed with the second slave gear 553 and in which the
electric module 330 is in driving engagement with the HP shaft 25c,
125c; and a neutral position depicted in FIG. 9 and in which the
electric module 330 is disengaged from both of the LP and HP shafts
24c, 124c, 25c, 125c.
[0077] The actuator 333 is therefore operable to move the master
gear 551 to selectively mesh the master gear 551 with either the
first slave gear 552 or with the second slave gear 553 or to
dispose the master gear 551 in its neutral position. The actuator
333 may be a solenoid, a hydraulic actuator, a pneumatic actuator,
or any other suitable actuators.
[0078] Referring to FIGS. 7-9, to start the gas turbine engine 11,
111, the electric module 130, 230, 330 is drivingly engaged to the
HP shaft 25c, 125c by moving the master gear 351, 451, 551 in
meshing engagement with the second slave gear 353, 453, 553. The
electric module 130, 230, 330 is set in torque mode or in speed
mode. The electric module 130, 230, 330 is operated to reach torque
or speed targets to assist ignition (rotate the HP shaft 25c, 125c
at optimum ignition conditions until a temperature rise in the gas
turbine engine 11, 111 is observed) and then helps the HP shaft
25c, 125c accelerate to an idle rotational speed. In some cases,
when the electric module 130, 230, 330 is drivingly engaged to the
HP shaft 25c, 125c, the electric module 130, 230, 330 may be
operated in torque mode to provide torque assist or in power
extraction mode to generate electricity.
[0079] The HP shaft 25c, 125c may be disengaged from the electric
module 130, 230, 330 either by setting a torque target of the
electric module 130, 230, 330 to zero to off-load the transmission
440, 540, 640 or by setting a speed target of the electric module
130, 230, 330 to match a speed of the second slave gear 353, 453,
553 such that speed is matched but that there is no torque
transmission between the electric module and the HP shaft. At which
point, the electric module 130, 230, 330 may be disengaged from the
HP shaft 25c, 125c. In the embodiment shown, the disengagement of
the electric module 130, 230, 330 from the HP shaft 25c, 125c is
done by disengaging the master gear 351, 451, 551 from the first
slave gear 353, 453, 553.
[0080] In some cases, the electric module 130, 230, 330 may be shut
down. To do so, the electric module may be set to speed mode and
the speed may be set to a minimum controllable speed or to zero to
decelerate the motor rapidly. Then, the electric module 130, 230,
330 may be turned off. Alternatively, the electric module 130, 230,
330 may be simply turned off and let to slow down on its own.
[0081] In some other cases, it may be desired to connect to LP
shaft 24c, 124c to the electric module 130, 230, 330 while the LP
shaft 24c, 124c is rotating. To do so, the electric module 130,
230, 330 may be operated in speed mode to match rotational speeds
of the master gear 351, 452, 551 and first slave gear 352, 452,
552. Once the speeds of the master gear and of the first slave gear
are matched, they may be meshed with one another to drivingly
engage the electric module 130, 230, 330 to the LP shaft 24c,
124c.
[0082] In some cases, it may be desired to drivingly engage the
electric module 130, 230, 330 to the LP shaft 24c, 124c while the
LP shaft 24c, 124c is not rotating, that is, when the HP shaft 25c,
125c is rotating but not the LP shaft because a brake is applied on
the propeller 12 or output shaft 112. The electric module 130, 230,
330 is first turned off and when the shaft 131, 231, 331 and the
master gear 351, 451, 551 are at rest, the electric module 130,
230, 330 is drivingly engaged to the LP shaft 24c, 124c by meshing
the master gear 351, 451, 551 to the first slave gear 352, 452,
552. Once the electric module 130, 230, 330 is drivingly engaged to
the LP shaft 24c, 124c, the electric module 130, 230, 330 may be
set in torque mode and a positive torque target may be sent to the
electric module 130, 230, 330 such that the electric module 130,
230, 330 and the LP shaft 24c, 124c compound their power to drive
the propeller 12 and output shaft 112. Alternatively, a negative
torque target may be sent to the electric module 130, 230, 330 such
that power is extracted from the LP shaft 24c, 124c to generate
electricity with the electric module 130, 230, 330.
[0083] The embodiments of the transmission 440, 540, 640 described
above with reference to FIGS. 7-9 may reduce drag or losses of the
electric module 130, 230, 330 when running on fuel power only. This
is possible by the possibility to set the master gear 351, 451, 551
in a neutral position in which the electric module 130, 230, 330 is
disengaged from both of the HP and LP shafts. Moreover, it may be
advantageous to have the possibility to disengage the electric
module 130, 230, 330 from both of the HP and LP shafts in a
situation where a malfunction occurs with the electric module 130,
230, 330.
[0084] Referring now to FIG. 10, an hybrid power plant in
accordance with another embodiment is shown at 210. The hybrid
power plant 210 includes the electric module 30 and the turboprop
gas turbine engine 11 described above with reference to FIG. 1.
[0085] In the embodiment shown, the electric module 30 is directly
and permanently drivingly engaged to the LP shaft 24c. The LP shaft
24c is drivingly engaged to the HP shaft 25c via a sprag clutch
745. During engine start, the electric module 30 provides a torque
to accelerate the LP shaft 24c directly and to accelerate the HP
shaft 25c via the LP shaft 24c and via the sprag clutch 745 until
the HP shaft 25c reaches a desired speed that is sufficient to
sustain combustion in the combustion chamber 26. When combustion
starts, the HP shaft 25c accelerates and becomes disengaged from
the LP shaft 24c that rotates at a lower rotational speed than that
of the HP shaft 25c. After engine start, the electric module 30 may
be used as a generator to extract energy from the LP shaft 24c or
may be used to compound power with the LP shaft 24c to drive the
propeller 12.
[0086] It will be understood that, in an alternate embodiment, the
sprag clutch 745 may be replaced by any other suitable kind of
clutches (e.g., viscous clutch) that is operable to selectively
engage or disengage the LP shaft 24c from the HP shaft 25c.
[0087] Referring now to FIG. 11, an hybrid power plant in
accordance with another embodiment is shown at 310. The hybrid
power plant 310 includes the electric module 30 and the turboshaft
gas turbine engine 111 described above with reference to FIG.
2.
[0088] In the embodiment shown, the electric module 30 is directly
and permanently drivingly engaged to the LP shaft 124c. The LP
shaft 124c is drivingly engaged to the HP shaft 125c via a sprag
clutch 745. During engine start, the electric module 30 provides a
torque to accelerate the LP shaft 124c directly and to accelerate
the HP shaft 125c via the LP shaft 124c and the sprag clutch 745
until the HP shaft 125c reaches a desired speed that is sufficient
to sustain combustion in the combustion chamber 126. When
combustion starts, the HP shaft 125c accelerates and becomes
disengaged from the LP shaft 124c since the LP shaft 124c rotates
at a lower rotational speed than that of the HP shaft 125c. After
engine start, the electric module 30 may be used as a generator to
extract energy from the LP shaft 124c or may be used to compound
power with the LP shaft 124c to drive the output shaft 112.
[0089] It will be understood that, in an alternate embodiment, the
sprag clutch 745 may be replaced by any other suitable kind of
clutches (e.g., viscous clutch) that is operable to selectively
engage or disengage the LP shaft 124c from the HP shaft 125c.
[0090] Referring now to FIG. 12, a control system for the hybrid
power plants 10, 110, 210, 310 is shown at 1000. The control system
1000 includes a controller 1002 having a processing unit 1004
communicating with a computer-readable medium 1006. The
computer-readable medium 1006 has instructions stored thereon
executable by the processing unit 1004 for receiving speed data of
the electric module 30, 130, 230, 330 from a speed sensor 1008
operatively connected to the controller 1002 and/or for receiving
torque data of the electric module 30, 130, 230, 330 from a torque
sensor 1010 operatively connected to the controller 1002. The
controller 1002 is further operatively connected to the
transmission 40, 140, 240, 340, 440, 540, 640 and to the electric
module 30, 130, 230, 330.
[0091] The instructions executable by the processing unit 1004 are
configured to control operation of the electric module 30, 130,
230, 330 and of the transmission 40, 140, 240, 340, 440, 540, 640.
That is, the controller 1002 is able to set the electric module 30,
130, 230, 330 in the torque mode or in the speed mode. When a
torque target is provided to the electric module 30, 130, 230, 330,
the controller 1002 varies a torque generated by the electric
module 30, 130, 230, 330 until the torque sensor 1008 notifies the
controller 1002 that the target torque is reached. Similarly, when
a speed target is provided to the electric module 30, 130, 230,
330, the controller 1002 varies a speed of the electric module 30,
130, 230, 330 until the speed sensor 1010 notifies the controller
1002 that the speed target is reached.
[0092] The instructions executable by the processing unit 1004 are
configured to control operation of the different clutches 44, 45,
145, 344, of the different actuators 133, 233, 333, and of the
different continuously variable transmissions 252, 253. Namely, the
controller 1002 is able to control all of the steps described above
to start the gas turbine engine 11, 111 and to selectively engage
the electric module 30, 130, 230, 330 to the LP shaft 24c, 124c
either to assist in driving the propeller 12 (FIG. 1) and output
shaft 112 (FIG. 2) or to operate the electric module 30, 130, 230,
330 in generation mode to extract energy from the LP shaft 24c,
124c to generate electricity.
[0093] In the embodiment shown, the electric motor includes a motor
controller 1012 or inverter that is operable to adjust current to
achieve either a torque or a speed target determined by the
controller 1002. In other words, the electric motor may include its
own motor controller 1012 operatively connected to the controller
1002. The torque sensors and speed sensors may be operatively
connected to the motor controller 1012 or to the controller 1002 as
shown. The controller 1002 may also receive torque and speed
information electronically from the motor controller 1012. The
controller 1002 may command transmission actuators as needed, based
on the instructions stored on the computer readable medium 1006 and
based on external signals such as command inputs, speeds and torque
information.
[0094] For starting a hybrid aircraft power plant, the
high-pressure spool is drivingly engaged to the electric motor; a
rotational speed of the high-pressure spool is increased to a
target rotational speed; a mixture of air and fuel is ignited into
a combustor of the gas turbine engine when the rotational speed of
the high-pressure spool is at the target rotational speed; and a
torque is transmitted between a low-pressure spool of the gas
turbine engine and the electric motor.
[0095] In some embodiments, the electric motor is disengaged from
the high-pressure spool after the igniting of the mixture of the
air and the fuel in to the combustor.
[0096] In some cases, the drivingly engaging of the electric motor
to the high-pressure spool includes switching a clutch from a
disengaged configuration to an engaged configuration or includes
operating a continuously variable transmission in a torque
transmission mode. In some cases, the drivingly engaging of the
electric motor to the high-pressure spool includes driving the
low-pressure spool with the electric motor and transmitting a
torque from the low-pressure shaft to the high-pressure shaft via a
sprag clutch. In some cases, the drivingly engaging of the electric
motor to the high-pressure spool includes meshing a master gear
drivingly engaged to the electric motor with a first slave gear
drivingly engaged to the high-pressure spool, and wherein the
transmitting of the torque between the electric motor and the
low-pressure spool includes disengaging the master gear from the
first slave gear and meshing the master gear to a second slave gear
drivingly engaged to the low-pressure spool. In some cases, the
transmitting of the torque between the electric motor and the
low-pressure spool of the gas turbine engine includes switching a
clutch from a disengaged configuration to an engaged configuration
or includes operating a continuously variable transmission in a
torque transmission mode.
[0097] The present disclosure may allow to have a single electric
motor for providing or extracting torque to/from the HP and LP
spools. Having a single electric motor may save weight, reduce
factory standard cost, and size of the power plant.
[0098] The embodiments described in this document provide
non-limiting examples of possible implementations of the present
technology. Upon review of the present disclosure, a person of
ordinary skill in the art will recognize that changes may be made
to the embodiments described herein without departing from the
scope of the present technology. For example, although the electric
modules and transmissions have been described as being coupled to
turboprop and turboshaft gas turbine engines, the electric modules
and transmissions of the present disclosure may be alternatively
coupled to a turbofan gas turbine engine. Yet further modifications
could be implemented by a person of ordinary skill in the art in
view of the present disclosure, which modifications would be within
the scope of the present technology.
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