U.S. patent application number 13/210121 was filed with the patent office on 2012-08-09 for gas turbine engine braking method.
This patent application is currently assigned to ICR TURBINE ENGINE CORPORATION. Invention is credited to David William Dewis, Frank Wegner Donnelly.
Application Number | 20120201657 13/210121 |
Document ID | / |
Family ID | 46600736 |
Filed Date | 2012-08-09 |
United States Patent
Application |
20120201657 |
Kind Code |
A1 |
Donnelly; Frank Wegner ; et
al. |
August 9, 2012 |
GAS TURBINE ENGINE BRAKING METHOD
Abstract
The present disclosure discloses an engine braking system,
especially for vehicles powered by a gas turbine. The engine
braking system allows for control of engine braking force; control
of over-speed of the power turbine and further includes means of
recovering some or all of the braking energy of the engine braking
system. Dissipative engine braking devices include an auxiliary
compressor, or electrical generator, or an eddy current clutch or
an eddy current brake, or fluid pump. Several methods of
controlling the engine braking force of a dissipative braking
device are disclosed and include (1) a continuously variable
transmission ("CVT"); (2) an electrical generator and an optional
thermal storage device; (3) an eddy current clutch; and (4) a fluid
pump system. The various control devices may be operated
automatically by appropriate algorithms. One of these control
methods utilizes an eddy current clutch assembly. An innovative
configuration of eddy current clutch assembly based on a brushless
alternator is disclosed. Additional innovations include vehicle
braking systems that utilize some or all the braking features to
recoup a portion of braking energy available with either or both of
a hybrid transmission and a dissipative braking device such as a
compressor, an electrical generator or a fluid pump system.
Inventors: |
Donnelly; Frank Wegner;
(North Vancouver, CA) ; Dewis; David William;
(North Hampton, NH) |
Assignee: |
ICR TURBINE ENGINE
CORPORATION
Hampton
NH
|
Family ID: |
46600736 |
Appl. No.: |
13/210121 |
Filed: |
August 15, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61440746 |
Feb 8, 2011 |
|
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Current U.S.
Class: |
415/123 |
Current CPC
Class: |
Y02T 50/671 20130101;
F02C 6/20 20130101; Y02T 50/60 20130101 |
Class at
Publication: |
415/123 |
International
Class: |
F01D 15/12 20060101
F01D015/12 |
Claims
1. In a vehicle comprising a gas turbine engine and a transmission,
the gas turbine engine comprising at least one turbo-compressor
spool assembly, wherein the at least one turbo-compressor spool
assembly comprises a compressor in mechanical communication with a
turbine, the turbine outputting a gas, and a free power turbine in
fluid communication with the turbine, the free power turbine being
driven by the outputted gas, a system comprising: a braking device
in mechanical communication with the free power turbine and the
transmission to at least one of dissipate energy of the free power
turbine and provide a braking force to the vehicle, wherein at
least one of the following is true: (a) the braking device
comprises a compressor selectively mechanically engaged and
disengaged from the free power turbine and/or the transmission of
the vehicle by a clutch assembly: (b) the braking device comprises
a continuously variable transmission; (c) the braking device
comprises an electrical generator configured to generate a selected
amount of electrical energy; (d) the braking device comprises at
least one of an eddy current clutch and an eddy current brake; and
(e) the braking device comprises a fluid pump circuit.
2. The system of claim 1, wherein the transmission comprises: a
first gear assembly comprising a high speed bull gear in mechanical
communication with a first shaft, a high speed pinion gear in
mechanical communication with the free power turbine, and a power
take off pinion gear in mechanical communication with the braking
device, the high speed bull gear being in mechanical communication
with the high speed pinion and the power takeoff pinion; and a
second gear assembly comprising a low speed bull gear in mechanical
communication with a second shaft and a low speed pinion in
mechanical communication with the first shaft, the low speed bull
gear being in mechanical communication with the low speed
pinion.
3. The system of claim 2, wherein the transmission comprises: a
clutch assembly to selectively engage and disengage the braking
device with the transmission wherein: in a normal driving mode, the
clutch assembly disengages the braking device from the
transmission; and in a braking mode, the clutch assembly engages
the braking device with the transmission.
4. The system of claim 2, wherein (a) is true.
5. The system of claim 4, wherein the braking compressor comprises
at least one of an inlet and outlet nozzle of a variable area, and
wherein: in a normal driving mode, the nozzle has a first
cross-sectional area normal to gas flow; and in a braking mode, the
nozzle has a second cross-sectional area normal to gas flow, the
first cross-sectional area being different from the second
cross-sectional area, wherein less power is dissipated by the
braking compressor in the normal driving mode than in the braking
mode.
6. The system of claim 5, wherein output gas from the braking
compressor is at least one of used to charge a pneumatic storage
tank and quench a hot gas from a recuperator to assist in engine
turndown, the output gas being introduced into an exhaust flow
upstream of an input to a hot side of the recuperator.
7. The system of claim 1, wherein (b) is true and wherein the
continuously variable transmission is positioned mechanically
between a load and the free power turbine.
8. The system of claim 7, further comprising an increasing gearbox
positioned mechanically between the continuously variable
transmission and a braking compressor.
9. The system of claim 7, further comprising a clutch assembly to
selectively engage and disengage the continuously variable
transmission from mechanical communication with the free power
turbine and the transmission.
10. The system of claim 1, wherein (c) is true, wherein the
electrical generator is configured to generate the electrical
energy in response to free power turbine rotation.
11. The system of claim 10, wherein a control excitation of the
electrical generator is controlled to generate the selected amount
of electrical energy and wherein the generated electrical energy is
carried via a conductive path to at least one of a dynamic braking
grid, an electrical energy storage system, and a thermal energy
storage device.
12. The system of claim 11, wherein the generator is positioned
mechanically between a clutch assembly and a braking
compressor.
13. The system of claim 1, wherein (d) is true.
14. The system of claim 13, wherein the braking device comprises an
eddy current clutch positioned mechanically between a load and the
free power turbine and wherein the eddy current clutch comprises:
an exciter armature rigidly connected to an input shaft and at
least one diode; a main field coil mechanically connected to the at
least one diode; a main armature rigidly connected to an output
shaft; and an exciter field coil, the exciter field coil being
substantially fixed relative to the free power turbine and
activated by one of a direct current and alternating current
control system; wherein the exciter armature is electrically
connected to the at least one diode by one of an alternative
current and direct current wire and the at least one diode is
electrically connected to the main field coil by the other of an
alternating current and direct current wire; and wherein the
exciter armature, at least one diode and main field coil rotate
when the input shaft rotates.
15. The system of claim 1, wherein (e) is true.
16. The system of claim 15, wherein the fluid pump circuit is
engaged mechanically with the free power turbine and comprises: a
fluid pump; and a restrictor valve having a variable orifice size,
wherein the orifice size is varied to provide a variable retarding
force on at least one of the free power turbine and the
transmission.
17. The system of claim 16, wherein the pump is in mechanical and
fluid communication with a lubrication system of at least one of
the engine and the transmission.
18. The system of claim 1, further comprising: a spur gear
mechanically connected to the braking device; a plurality of planet
gears; a planet carrier in mechanical communication with the
plurality of planet gears; a sun gear in mechanical communication
with plurality of planet gears; and a ring gear in mechanical
communication with the spur gear and the plurality of planet gears,
wherein the spur gear is in mechanical communication with a first
braking device, wherein the sun gear is in mechanical communication
with a second braking device, and wherein a low input shaft is in
mechanical communication with the planet carrier and a clutch
assembly to selectively engage and disengage the first and second
braking devices from mechanical communication with the free power
turbine and the transmission.
19. In a vehicle comprising a gas turbine engine and a transmission
comprising at least one turbo-compressor spool assembly, the at
least one turbo-compressor spool assembly comprising a compressor
in mechanical communication with a turbine, the turbine outputting
a gas, a free power turbine in fluid communication with the
turbine, the free power turbine being driven by the outputted gas,
and a braking device in mechanical communication with the free
power turbine and the transmission, a method comprising: performing
at least one of the following steps: (a) in response to a sensed
revolutions-per-minute of the free power turbine, selectively
engaging and disengaging a braking device from mechanical
communication with the free power turbine, the braking device
retarding rotation of the free power turbine; (b) in response to a
sensed braking request of the vehicle, selectively engaging and
disengaging a braking device from mechanical communication with the
free power turbine, the braking device providing a braking force to
the vehicle; (c) varying, by an continuously variable transmission,
a gear ratio continuously between first and second gear ratios, the
gear ratio being for a mechanical linkage between a braking device
and the clutch assembly; (d) generating, by an electrical
generator, a selected amount of electrical energy to provide at
least one of a selected amount of retardation force against
rotation of the free power turbine and a selected amount braking
force to the vehicle; (e) applying torque by at least one of an
eddy current brake and eddy current clutch to provide at least one
of a selected amount of retardation force against rotation of the
free power turbine and a selected amount braking force to the
vehicle; and (f) intermittently operating a fluid pump in
mechanical communication with the free power turbine to provide at
least one of a selected amount of retardation force against
rotation of the free power turbine and a selected amount braking
force to the vehicle.
20. The method of claim 19, wherein the braking device is
selectively mechanically engaged and disengaged from the free power
turbine and/or the transmission of the vehicle by a clutch assembly
and wherein the transmission comprises: a first gear assembly
comprising a high speed bull gear in mechanical communication with
a first shaft, a high speed pinion gear in mechanical communication
with the free power turbine, and a power take off pinion gear in
mechanical communication with the braking device, the high speed
bull gear being in mechanical communication with the high speed
pinion and the power takeoff pinion; and a second gear assembly
comprising a low speed bull gear in mechanical communication with a
second shaft and a low speed pinion in mechanical communication
with the first shaft, the low speed bull gear being in mechanical
communication with the low speed pinion.
21. The method of claim 20, further comprising: selectively
disengaging the braking device with the transmission in a normal
driving mode; and selectively engaging the braking device with the
transmission in a braking mode.
22. The method of claim 19, wherein at least one of step (a) and
step (b) is performed.
23. The method of claim 22, wherein the braking device comprises at
least one of an inlet and outlet nozzle of a variable area and
wherein: in a normal driving mode, the nozzle has a first
cross-sectional area normal to the at least a portion of the gas
flow; and in a braking mode, the nozzle has a second
cross-sectional area normal to gas flow, the first cross-sectional
area being different from the second cross-sectional area, wherein
less power is dissipated by the braking device in the normal
driving mode than in the braking mode.
24. The method of claim 23, wherein output gas from the braking
compressor is at least one of used to charge a pneumatic storage
tank and quench a hot gas from a recuperator to assist in engine
turndown, the output gas being introduced into an exhaust flow
upstream of an input to a hot side of the recuperator.
25. The method of claim 19, wherein step (c) is performed.
26. The method of claim 25, further comprising positioning an
increasing gearbox positioned between the continuously variable
transmission and a braking compressor.
27. The method of claim 26, wherein step (d) is performed.
28. The method of claim 19, wherein a control excitation of the
electrical generator is controlled to generate the selected amount
of electrical energy and wherein the generated electrical energy is
carried via a conductive path to at least one of a dynamic braking
grid, an electrical energy storage system, and a thermal energy
storage device.
29. The method of claim 27, wherein the generator is positioned
mechanically between a clutch assembly and a load.
30. The method of claim 19, wherein step (e) is performed.
31. The method of claim 20, wherein the at least one of eddy
current brake and clutch is the eddy current clutch and wherein the
eddy current clutch comprises: applying one of a direct and
alternating electrical current to an exciter field coil to induce
the other of a direct and alternating current in an exciter
armature; rectifying the induced current to the one of direct and
alternating current and causing the one of the direct and
alternating current in a main field coil; causing a rotational
force in a main armature; wherein the exciter armature and main
field coil rotate when an input shaft rotates and the main armature
rotates when an output shaft rotates.
32. The method of claim 19, wherein step (f) is performed.
33. The method of claim 32, wherein the fluid pump is in
communication with a restrictor valve having a variable orifice
size, wherein the orifice size is varied to provide a variable
retarding force on at least one of the free power turbine and the
transmission.
34. The method of claim 33, wherein the fluid pump is in mechanical
communication with a lubrication system of at least one of the
engine and the transmission.
35. The method of claim 20, wherein the braking device further
comprises: a spur gear mechanically connected to the braking
device; a plurality of planet gears; a planet carrier in mechanical
communication with the plurality of planet gears; a sun gear in
mechanical communication with plurality of planet gears; and a ring
gear in mechanical communication with the spur gear and the
plurality of planet gears, wherein the spur gear is in mechanical
communication with a first braking device, wherein the sun gear is
in mechanical communication with a second braking device, and
wherein a low input shaft is in mechanical communication with the
planet carrier and clutch assembly to selectively engage and
disengage the first and second braking devices from mechanical
communication with the free power turbine and the transmission.
36. A vehicle, comprising: (a) an engine; (b) a transmission; (c) a
braking device to maintain or reduce the ground velocity of the
vehicle; and at least one of the following braking device control
devices: (C1) a continuously variable transmission positioned
mechanically with respect to the braking device, the transmission
and the engine; (C2) an electrical generator configured to generate
a selected amount of electrical energy to provide a selected amount
of retardation force against rotation of a shaft of the engine;
(C3) at least one of an eddy current clutch and eddy current brake
positioned mechanically with respect to the braking device, the
transmission and the engine; and (C4) a pump and restrictor valve
in fluid communication with the braking device.
37. The vehicle of claim 36, wherein the engine is a gas turbine
engine and comprises at least one turbo-compressor spool assembly,
wherein the at least one turbo-compressor spool assembly comprises
a compressor in mechanical communication with a turbine, the
turbine outputting a gas and a free power turbine in fluid
communication with the turbine, the free power turbine being driven
by the outputted gas, wherein the braking compressor is in
mechanical communication with the free power turbine to dissipate
power of the free power turbine.
38. The vehicle of claim 37, wherein the transmission comprises:
(B1) a first gear assembly comprising a high speed bull gear in
mechanical communication with a first shaft, a high speed pinion
gear in mechanical communication with the free power turbine, and a
power take off pinion gear in mechanical communication with the
braking compressor, the high speed bull gear being in mechanical
communication with the high speed pinion and the power takeoff
pinion; and (B2) a second gear assembly comprising a low speed bull
gear in mechanical communication with a second shaft and a low
speed pinion in mechanical communication with the first shaft, the
low speed bull gear being in mechanical communication with the low
speed pinion.
39. The vehicle of claim 36, further comprising: (C3) a clutch
assembly to selectively engage and disengage the braking compressor
with the transmission wherein: in a normal driving mode, the clutch
assembly disengages the braking compressor from the transmission;
and in a braking mode, the clutch assembly engages the braking
compressor with the transmission.
40. The vehicle of claim 37, wherein the braking compressor
comprises at least one of an inlet and outlet nozzle of a variable
area, and wherein: in a normal driving mode, the nozzle has a first
cross-sectional area normal to gas flow; and in a braking mode, the
nozzle has a second cross-sectional area normal to gas flow, the
first cross-sectional area being different from the second
cross-sectional area, wherein less power is dissipated by the
braking compressor in the normal driving mode than in the braking
mode.
41. The vehicle of claim 40 wherein output gas from the braking
compressor is at least one of used to charge a pneumatic storage
tank and quench a hot gas from a recuperator to assist in engine
turndown, the output gas being introduced into an exhaust flow
upstream of an input to a hot side of the recuperator.
42. The vehicle of claim 37, wherein (C1) is true.
43. The vehicle of claim 42, further comprising an increasing
gearbox positioned mechanically between the continuously variable
transmission and a braking compressor.
44. The vehicle of claim 42, further comprising a clutch assembly
to selectively engage and disengage the continuously variable
transmission from mechanical communication with the free power
turbine and the transmission.
45. The vehicle of claim 37, wherein (C2) is true.
46. The vehicle of claim 45, wherein a control excitation of the
electrical generator is controlled to generate the selected amount
of electrical energy and wherein the generated electrical energy is
carried via a conductive path to at least one of a dynamic braking
grid, an electrical energy storage system, and a thermal energy
storage device.
47. The vehicle of claim 46, wherein the generator is positioned
mechanically between a clutch assembly and a braking
compressor.
48. The vehicle of claim 37, wherein (C3) is true.
49. The vehicle of claim 48, wherein the eddy current clutch
comprises: an exciter armature rigidly connected to an input shaft
and at least one diode; a main field coil mechanically connected to
the at least one diode; a main armature rigidly connected to an
output shaft; and an exciter field coil, the exciter field coil
being substantially fixed relative to the free power turbine and
activated by one of a direct current and alternating current
control system; wherein the exciter armature is electrically
connected to the at least one diode by one of an alternative
current and direct current wire and the at least one diode is
electrically connected to the main field coil by the other of an
alternating current and direct current wire; and wherein the
exciter armature, at least one diode and main field coil rotate
when the input shaft rotates.
50. The vehicle of claim 37, wherein (C4) is true.
51. The vehicle of claim 50, wherein the fluid pump circuit
comprises: a fluid pump; and a restrictor valve having a variable
orifice size, wherein the orifice size is varied to provide a
variable load on the free power turbine.
52. The vehicle of claim 51, wherein the pump is in mechanical
communication with a lubrication system of at least one of the
engine and the transmission.
53. The braking device of claim 37, wherein the transmission
comprises: (B1) a spur gear mechanically connected to the braking
compressor; (B2) a plurality of planet gears; (B3) a planet carrier
in mechanical communication with the plurality of planet gears;
(B4) a sun gear in mechanical communication with plurality of
planet gears; and (B5) a ring gear in mechanical communication with
the spur gear and the plurality of planet gears, wherein the spur
gear is in mechanical communication with a first braking device,
wherein the sun gear is in mechanical communication with a second
braking device, and wherein a low input shaft is in mechanical
communication with the planet carrier and a clutch assembly to
selectively engage and disengage the first and second braking
devices from mechanical communication with the free power turbine
and the transmission.
54. A tangible or non-transient computer readable medium comprising
microprocessor-executable instructions operable to perform at least
the following steps: a) sensing at least one of a revolutions per
minute ("rpms") of a free power turbine, at least one of an on and
off state of a braking device clutch, at least one of an on and off
state of a transmission clutch, and a braking device control
setting; b) based on the sensed at least one of a revolutions per
minute ("rpms") of a free power turbine, at least one of an on and
off state of a braking device clutch, at least one of an on and off
state of a transmission clutch, and a braking device control
setting, determining that the free power turbine requires
over-speed control; c) in response to step (b), disengaging the
transmission clutch and engaging the braking device clutch; d)
reducing the rpms of the free power turbine by controlling an
amount of energy dissipation of the braking device; e) during step
(d), sensing rpms of the free power turbine and reducing the rpms
of the free power turbine until the rpms of the free power turbine
are reduced to less than or equal to a selected value; and f) when
the rpms of the free power turbine are less than the selected
value, disengaging the braking device clutch.
55. A tangible or non-transient computer readable medium comprising
microprocessor-executable instructions operable to perform at least
the following steps: a) sensing at least one of an on and off state
of braking device clutch, at least one of an on and off state of a
transmission clutch, a vehicle ground velocity, a transmission gear
setting, and a braking device control setting; b) based on the
sensed at least one of a vehicle ground velocity, at least one of
an on and off state of a braking device clutch, at least one of an
on and off state of a transmission clutch, and a braking device
control setting, determining that engine braking is required; c) in
response to step (b), engaging the braking device clutch and
engaging the transmission clutch for engine braking; d) increasing
a vehicle braking force opposing a direction of motion of the
vehicle by controlling an amount of energy dissipation of the
braking device; e) during step (d), sensing a vehicle ground
velocity and applying the engine braking force until the vehicle
ground velocity is less than or equal to a selected value; and f)
when the vehicle ground velocity is less than or equal to the
selected value, disengaging the braking device clutch.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present application claims the benefits, under 35 U.S.C.
.sctn.119(e), of U.S. Provisional Application Ser. No. 61/440,746
entitled "Gas Turbine Engine Braking Method" filed on Feb. 8, 2011,
which is incorporated herein by reference.
FIELD
[0002] The present disclosure on relates generally to gas turbine
engine systems and specifically to a method and apparatus that can
provide control of power turbine over-speed and engine braking to a
vehicle.
BACKGROUND
[0003] There is a growing requirement for alternate fuels for
vehicle propulsion. These include fuels such as natural gas,
bio-diesel, ethanol, butanol, hydrogen and the like. Means of
utilizing fuels needs to be accomplished more efficiently and with
substantially lower carbon dioxide emissions and other air
pollutants such as NOxs.
[0004] The gas turbine or Brayton cycle power plant has
demonstrated many attractive features which make it a candidate for
advanced vehicular propulsion. Gas turbine engines have the
advantage of being highly fuel flexible and fuel tolerant.
Additionally, these engines burn fuel at a lower temperature than
reciprocating engines so produce substantially less NOxs per mass
of fuel burned.
[0005] However, the gas turbine does not allow the normal "engine
braking" or "compression braking" feature that is extensively used
in piston-type engines. The utility of these engines, especially
for use in large vehicles such as Class 8 trucks, can be
substantially improved by providing an engine braking capability
analogous to the Jacobs brake used by piston engine powered
trucks.
[0006] In addition, configurations of gas turbine engines which
employ a free power turbine require additional means to control
over-speeding of the free power turbine. Such over-speeding can
occur in vehicle or other applications, for example, when the load
is abruptly reduced or disconnected.
[0007] U.S. Pat. No. 3,817,343 "Installation for Brake of Motor
Vehicles Which Are Driven from a Gas Turbine" discloses a means for
the braking of motor vehicles which are driven by a gas turbine
engine comprising a free output or free power turbine, by means of
a rotary compressor that is arranged in or parallel to the
transmission and is in the power path from the free working turbine
to the driven wheels. U.S. Pat. No. 3,817,343 does not teach how to
control the braking force of the braking compressor nor how to
utilize the output of the braking compressor for recovering useful
energy.
[0008] There thus remains a need for compact, controllable engine
braking apparatus to improve engine braking performance so as to
assist the vehicle's foundation braking system. There is also a
need, for vehicles powered by gas turbine engines, for a means of
over-speed control of the free power turbine.
SUMMARY
[0009] Accordingly, it is an object of the present disclosure to
provide an engine braking system, especially for vehicles powered
by a gas turbine. The engine braking system of the present
disclosure allows for control of auxiliary engine braking force;
control of over-speed of the power turbine; generation of air used
for quenching hot recuperator gases to assist in engine turndown;
and further includes means of recovering some or all of the braking
energy of the engine braking system.
[0010] As mentioned, U.S. Pat. No. 3,817,343 teaches use of a
rotary compressor which can act as an auxiliary braking systems on
large vehicles such as Class 8 trucks. U.S. Pat. No. 3,817,343 does
not teach how to control the braking force nor does it teach how to
utilize the energy dissipated by the braking compressor.
[0011] Several braking devices are disclosed. These include energy
dissipative devices such as, for example, a compressor, an
electrical generator, a fluid pump system and an eddy current brake
or clutch. The present disclosure includes several methods of
controlling the engine braking force of a braking device. Such
control devices disclosed herein include (1) a continuously
variable transmission ("CVT"); (2) an electrical generator and an
optional thermal storage device; (3) an eddy current clutch; and
(4) a fluid pump system. As can be appreciated, the various control
devices may be controlled automatically by an appropriate control
algorithm which is responsive to the data from various shaft rpms,
free power turbine rpms and braking instructions.
[0012] One of these control methods utilizes an eddy current
clutch. An innovative configuration of eddy current clutch based on
a brushless alternator is disclosed.
[0013] Additional innovations disclosed herein include vehicle
braking systems that utilize some or all the braking features to
recoup a portion of braking energy available with either or both of
a hybrid transmission and a braking compressor.
[0014] It is noted that the engine braking system of the present
disclosure is a form of dynamic braking since the braking force
applied to the vehicle only exists when the vehicle is in motion
and when the engine braking system is caused to be connected to the
vehicle's drive train.
[0015] These and other advantages will be apparent from the
disclosure contained herein.
[0016] In one embodiment, a vehicle is disclosed comprising a gas
turbine engine and a transmission, the gas turbine engine
comprising at least one turbo-compressor spool assembly, wherein
the at least one turbo-compressor spool assembly comprises a
compressor in mechanical communication with a turbine, the turbine
outputting a gas, and a free power turbine in fluid communication
with the turbine, the free power turbine being driven by the
outputted gas, a system comprising a braking device in mechanical
communication with the free power turbine and the transmission to
at least one of dissipate energy of the free power turbine and
provide a braking force to the vehicle, wherein at least one of the
following is true: (a) the braking device comprises a compressor
selectively mechanically engaged and disengaged from the free power
turbine and/or the transmission of the vehicle by a clutch
assembly: (b) the braking device comprises a continuously variable
transmission; (c) the braking device comprises an electrical
generator configured to generate a selected amount of electrical
energy; (d) the braking device comprises at least one of an eddy
current clutch and an eddy current brake; and (e) the braking
device comprises a fluid pump circuit.
[0017] In another embodiment, a method is disclosed system for a
vehicle comprising a gas turbine engine and a transmission
comprising at least one turbo-compressor spool assembly, the at
least one turbo-compressor spool assembly comprising a compressor
in mechanical communication with a turbine, the turbine outputting
a gas, a free power turbine in fluid communication with the
turbine, the free power turbine being driven by the outputted gas,
and a braking device in mechanical communication with the free
power turbine and the transmission, the method comprising
performing at least one of the following steps: (a) in response to
a sensed revolutions-per-minute of the free power turbine,
selectively engaging and disengaging a braking device from
mechanical communication with the free power turbine, the braking
device retarding rotation of the free power turbine; (b) in
response to a sensed braking request of the vehicle, selectively
engaging and disengaging a braking device from mechanical
communication with the free power turbine, the braking device
providing a braking force to the vehicle; (c) varying, by an
continuously variable transmission, a gear ratio continuously
between first and second gear ratios, the gear ratio being for a
mechanical linkage between a braking device and the clutch
assembly; (d) generating, by an electrical generator, a selected
amount of electrical energy to provide at least one of a selected
amount of retardation force against rotation of the free power
turbine and a selected amount braking force to the vehicle; (e)
applying torque by at least one of an eddy current brake and eddy
current clutch to provide at least one of a selected amount of
retardation force against rotation of the free power turbine and a
selected amount braking force to the vehicle; and (f)
intermittently operating a fluid pump in mechanical communication
with the free power turbine to provide at least one of a selected
amount of retardation force against rotation of the free power
turbine and a selected amount braking force to the vehicle.
[0018] In yet another embodiment, a vehicle is disclosed,
comprising an engine, a transmission, a braking device to maintain
or reduce the ground velocity of the vehicle; and at least one of
the following braking device control devices: 1) a continuously
variable transmission positioned mechanically with respect to the
braking device, the transmission and the engine, 2) an electrical
generator configured to generate a selected amount of electrical
energy to provide a selected amount of retardation force against
rotation of a shaft of the engine, 3) at least one of an eddy
current clutch and eddy current brake positioned mechanically with
respect to the braking device, the transmission and the engine, and
a pump and restrictor valve in fluid communication with the braking
device.
[0019] In another embodiment, a tangible or non-transient computer
readable medium is disclosed comprising microprocessor-executable
instructions operable to perform at least the following steps: a)
sensing at least one of a revolutions per minute ("rpms") of a free
power turbine, at least one of an on and off state of a braking
device clutch, at least one of an on and off state of a
transmission clutch, and a braking device control setting; b) based
on the sensed at least one of a revolutions per minute ("rpms") of
a free power turbine, at least one of an on and off state of a
braking device clutch, at least one of an on and off state of a
transmission clutch, and a braking device control setting,
determining that the free power turbine requires over-speed
control; c) in response to step (b), disengaging the transmission
clutch and engaging the braking device clutch; d) reducing the rpms
of the free power turbine by controlling an amount of energy
dissipation of the braking device; e) during step (d), sensing rpms
of the free power turbine and reducing the rpms of the free power
turbine until the rpms of the free power turbine are reduced to
less than or equal to a selected value; and f) when the rpms of the
free power turbine are less than the selected value, disengaging
the braking device clutch.
[0020] In another embodiment, a tangible or non-transient computer
readable medium is disclosed comprising microprocessor-executable
instructions operable to perform at least the following steps: a)
sensing at least one of an on and off state of braking device
clutch, at least one of an on and off state of a transmission
clutch, a vehicle ground velocity, a transmission gear setting, and
a braking device control setting; b) based on the sensed at least
one of a vehicle ground velocity, at least one of an on and off
state of a braking device clutch, at least one of an on and off
state of a transmission clutch, and a braking device control
setting, determining that engine braking is required; c) in
response to step (b), engaging the braking device clutch and
engaging the transmission clutch for engine braking; d) increasing
a vehicle braking force opposing a direction of motion of the
vehicle by controlling an amount of energy dissipation of the
braking device; e) during step (d), sensing a vehicle ground
velocity and applying the engine braking force until the vehicle
ground velocity is less than or equal to a selected value; and f)
when the vehicle ground velocity is less than or equal to the
selected value, disengaging the braking device clutch.
[0021] The above-described embodiments and configurations are
neither complete nor exhaustive. As will be appreciated, other
embodiments of the invention are possible utilizing, alone or in
combination, one or more of the features set forth above or
described in detail below.
[0022] The following definitions are used herein:
[0023] The term "a" or "an" entity refers to one or more of that
entity. As such, the terms "a" (or "an"), "one or more" and "at
least one" can be used interchangeably herein. It is also to be
noted that the terms "comprising", "including", and "having" can be
used interchangeably.
[0024] The term automatic and variations thereof, as used herein,
refers to any process or operation done without material human
input when the process or operation is performed. However, a
process or operation can be automatic, even though performance of
the process or operation uses material or immaterial human input,
if the input is received before performance of the process or
operation. Human input is deemed to be material if such input
influences how the process or operation will be performed. Human
input that consents to the performance of the process or operation
is not deemed to be "material".
[0025] A bell housing is a term for the portion of the transmission
that covers the flywheel and the clutch or torque converter of the
transmission on vehicles powered by internal combustion engines.
This housing is bolted to the engine block and derives its name
from the bell-like shape that its internal components necessitate.
The starter motor is usually mounted here, and engages with a ring
gear on the flywheel. On the opposite end to the engine is usually
bolted to the gearbox. The above is the normal arrangement for an
in-line transmission system for a conventional rear wheel drive or
all wheel drive vehicle. The arrangement for a transverse mounted
engine and transmission for a front wheel drive vehicle has the
gear box and differential below the engine and consequently the
bell housing is a simple cover for the flywheel.
[0026] A bull gear is the larger of two gears that are in
engagement. The smaller gear is usually referred to as a pinion
gear.
[0027] A brushless alternator is composed of two alternators built
end-to-end on one shaft. Smaller brushless alternators may look
like one unit but the two parts are readily identifiable on the
large versions. The larger of the two sections is the main
alternator and the smaller one is the exciter. The exciter has
stationary field coils and a rotating armature (power coils). The
main alternator uses the opposite configuration with a rotating
field and stationary armature. A bridge rectifier, called the
rotating rectifier assembly, is mounted on a plate attached to the
rotor. Neither brushes nor slip rings are used, which reduces the
number of wearing parts. The main alternator has a rotating field
as described above and a stationary armature (power generation
windings). Varying the amount of current through the stationary
exciter field coils varies the 3-phase output from the exciter.
This output is rectified by a rotating rectifier assembly, mounted
on the rotor, and the resultant DC supplies the rotating field of
the main alternator and hence alternator output. The result of all
this is that a small DC exciter current indirectly controls the
output of the main alternator.
[0028] As used herein, a clutch is a device used to connect or
disconnect flow of power from one part of a transmission from
another. For example, in a typical reciprocating engine vehicle,
the clutch is the mechanism in the drive train that connects the
engine crankshaft to or disconnects it from the gearbox thus with
the remainder of the drive train.
[0029] The term computer-readable medium as used herein refers to
any tangible or non-transient storage and/or transmission medium
that participate in providing instructions to a processor for
execution. Such a medium may take many forms, including but not
limited to, non-volatile media, volatile media, and transmission
media. Non-volatile media includes, for example, NVRAM, or magnetic
or optical disks. Volatile media includes dynamic memory, such as
main memory. Common forms of computer-readable media include, for
example, a floppy disk, a flexible disk, hard disk, magnetic tape,
or any other magnetic medium, magneto-optical medium, a CD-ROM, any
other optical medium, punch cards, paper tape, any other physical
medium with patterns of holes, a RAM, a PROM, and EPROM, a
FLASH-EPROM, a solid state medium like a memory card, any other
memory chip or cartridge, a carrier wave as described hereinafter,
or any other medium from which a computer can read. A digital file
attachment to e-mail or other self-contained information archive or
set of archives is considered a distribution medium equivalent to a
tangible or non-transient storage medium. When the
computer-readable media is configured as a database, it is to be
understood that the database may be any type of database, such as
relational, hierarchical, object-oriented, and/or the like.
Accordingly, the disclosure is considered to include a tangible or
non-transient storage medium or distribution medium and prior
art-recognized equivalents and successor media, in which the
software implementations of the present disclosure are stored.
[0030] A Continuously Variable Transmission or CVT has a low gear
ratio and a high gear ratio with infinitely many ratios in-between.
The advantage of a CVT is the ability to keep the engine's RPMs in
their optimum power output range for all operating conditions. A
vehicle with a CVT transmission can be readily diagnosed with
software. Unlike traditional automatic transmissions, continuously
variable transmissions don't have a gearbox with a set number of
gears, which means they don't have interlocking toothed wheels. The
most common type of CVT operates on a pulley system that allows an
infinite variability between highest and lowest gears with no
discrete steps or shifts. Other types of CVTs include toroidal and
hydrostatic.
[0031] DC bus means DC link and the terms may be used
interchangeably.
[0032] The terms determine, calculate and compute and variations
thereof, as used herein, are used interchangeably and include any
type of methodology, process, mathematical operation or
technique.
[0033] A differential connects a drive shaft to axles. While the
differential may provide gear reduction, its primary purpose is to
change the direction of rotation.
[0034] A drive train is the part of a vehicle or power generating
machine that transmits power from the engine to the driven members,
such as the wheels on a vehicle, by means of any combination of
belts, fluids, gears, flywheels, electric motors, clutches, torque
converters, shafts, differentials, axles and the like.
[0035] An eddy current brake is a type of electromagnetic brake in
which torque is applied to a rotating shaft by means of eddy
currents induced by a magnetic field set up by a conductor carrying
direct current in a fixed member forming one side of the brake and
inducing an opposing current in a conductor in a rotating member
forming the other side of the brake.
[0036] An eddy current clutch is a type of electromagnetic clutch
in which torque is transmitted by means of eddy currents induced by
a magnetic field set up by a conductor carrying direct current in a
member forming one side of the clutch and inducing an opposing
current in a conductor in a rotating member forming the other side
of the clutch.
[0037] An energy storage system refers to any apparatus that
acquires, stores and distributes mechanical or electrical energy
which is produced from another energy source such as a prime energy
source, a regenerative braking system, a third rail and a catenary
and any external source of electrical energy. Examples are a
battery pack, a bank of capacitors, a pumped storage facility, a
compressed air storage system, an array of a heat storage blocks, a
bank of flywheels or a combination of storage systems.
[0038] An engine is a prime mover and refers to any device that
uses energy to develop mechanical power, such as motion in some
other machine. Examples are diesel engines, gas turbine engines,
microturbines, Stirling engines and spark ignition engines.
[0039] An engine braking device as used herein is an auxiliary
braking apparatus that dissipates engine power when engaged. When
engaged, the engine braking device may dissipate power from the
engine when the transmission clutch is not engaged and may increase
vehicle braking force when the transmission clutch is engaged.
[0040] A free power turbine as used herein is a turbine which is
driven by a gas flow and whose rotary power is the principal
mechanical output power shaft. A free power turbine is not
connected to a compressor in the gasifier section, although the
free power turbine may be in the gasifier section of the gas
turbine engine. A power turbine may also be connected to a
compressor in the gasifier section in addition to providing rotary
power to an output power shaft.
[0041] The foundation braking system of a vehicle, as used herein,
comprise the drum and/or disc brakes associated with all or most of
the wheels of a vehicle.
[0042] A gear box as used herein is a housing that includes at
least one gear set. Typically, a gear box on a vehicle includes
switchable gear sets to provide multiple gear ratios, with the
ability to switch between them as speed varies. Directional
(forward and reverse) control may also be provided. This switching
may be done manually or automatically.
[0043] A gear set as used herein is a single ratio gear
assembly.
[0044] Jake brake or Jacobs brake describes a particular brand of
engine braking system. It is used generically to refer to engine
brakes or compression release engine brakes in general, especially
on large vehicles or heavy equipment. An engine brake is a braking
system used primarily on semi-trucks or other large vehicles that
modifies engine valve operation to use engine compression to slow
the vehicle. They are also known as compression release engine
brakes.
[0045] A mechanical-to-electrical energy conversion device refers
an apparatus that converts mechanical energy to electrical energy
or electrical energy to mechanical energy. Examples include but are
not limited to a synchronous alternator such as a wound rotor
alternator or a permanent magnet machine, an asynchronous
alternator such as an induction alternator, a DC generator, and a
switched reluctance generator. A traction motor is a
mechanical-to-electrical energy conversion device used primarily
for propulsion.
[0046] The term module as used herein refers to any known or later
developed hardware, software, firmware, artificial intelligence,
fuzzy logic, or combination of hardware and software that is
capable of performing the functionality associated with that
element. Also, while the disclosure is presented in terms of
exemplary embodiments, it should be appreciated that individual
aspects of the disclosure can be separately claimed
[0047] A permanent magnet motor is a synchronous rotating electric
machine where the stator is a multi-phase stator like that of an
induction motor and the rotor has surface-mounted permanent
magnets. In this respect, the permanent magnet synchronous motor is
equivalent to an induction motor where the air gap magnetic field
is produced by a permanent magnet. The use of a permanent magnet to
generate a substantial air gap magnetic flux makes it possible to
design highly efficient motors. For a common 3-phase permanent
magnet synchronous motor, a standard 3-phase power stage is used.
The power stage utilizes six power transistors with independent
switching. The power transistors are switched in ways to allow the
motor to generate power, to be free-wheeling or to act as a
generator by controlling frequency.
[0048] Over-speed control of a free power turbine means control of
the rpms of a free power turbine by preventing the rpms from
increasing beyond a selected value. Typically, a free power turbine
will over-speed if the gas driving the turbine remains on while the
load (transmission or electrical generator for example) is rapidly
or abruptly turned off.
[0049] A pinion is the smaller of two gears that are in engagement.
The larger gear is usually referred to as a bull gear.
[0050] A planetary gear (also known as an epicyclic gear) is a gear
system consisting of one or more outer gears, or planet gears,
revolving about a central, or sun gear (also known as a sun
pinion). Typically, the planet gears are mounted on a planet
carrier plate which itself may rotate relative to the sun gear.
Planetary gearing systems also incorporate the use of an outer ring
gear or orbit gear which meshes with the planet gears. In this gear
system, the sun gear engages all three planet gears simultaneously.
All three are attached to a planet carrier plate, and they engage
the inside of the ring gear. Because there are three planet gears
instead of one, the arrangement is extremely rugged. The output
shaft may be attached to the ring gear, and the planet carrier may
be held stationary. Alternately the output shaft may be attached to
the planet carrier and the ring gear may be held stationary.
Planetary gear sets can produce different gear ratios depending on
which gear is used as the input, which gear is used as the output
and which gear is held stationary. For instance, if the input is
the sun gear the ring gear is held stationary and the output shaft
is attached to the planet carrier, a particular gear ratio is
obtained. In this case, the planet carrier and planets orbit the
sun gear, so instead of the sun gear having to rotate six times for
the planet carrier to rotate once, it has to spin seven times. This
is because the planet carrier circles the sun gear once in the same
direction as it was spinning, subtracting one revolution from the
sun gear. So in this case, a 7:1 reduction is obtained. If the sun
gear is held stationary and the output is from the planet carrier
and the input is to the ring gear, a 1.17:1 gear reduction would be
obtained.
[0051] A prime power source refers to any device that uses energy
to develop mechanical or electrical power, such as motion in some
other machine. Examples are diesel engines, gas turbine engines,
microturbines, Stirling engines, spark ignition engines and fuel
cells.
[0052] A power control apparatus refers to an electrical apparatus
that regulates, modulates or modifies AC or DC electrical power.
Examples are an inverter, a chopper circuit, a boost circuit, a
buck circuit or a buck/boost circuit.
[0053] Power density as used herein is power per unit volume (watts
per cubic meter).
[0054] A recuperator is a heat exchanger that transfers heat
through a network of tubes, a network of ducts or walls of a matrix
wherein the flow on the hot side of the heat exchanger is typically
exhaust gas and the flow on cold side of the heat exchanger is
typically gas (for example, air or a fuel-air mixture) entering the
combustion chamber.
[0055] Regenerative braking is the same as dynamic braking except
the electrical energy generated is recaptured and stored in an
energy storage system for future use.
[0056] Specific power as used herein is power per unit mass (watts
per kilogram).
[0057] Spool means a group of turbo machinery components on a
common shaft.
[0058] A thermal energy storage module is a device that includes
either a metallic heat storage element or a ceramic heat storage
element with embedded electrically conductive wires. A thermal
energy storage module is similar to a heat storage block but is
typically smaller in size and energy storage capacity.
[0059] As used herein, a transmission is the part of a vehicle or
power generating machine that transmits power from the output shaft
of an engine to a drive shaft by means of any combination of belts,
fluids, gears, flywheels, electric generators, clutches, torque
converters and the like. A transmission may be a manual
transmission or an automatic transmission. A transmission may be an
all-mechanical apparatus or an apparatus with both mechanical and
electrical components. The latter may also be called a hybrid
transmission. In British usage, the term transmission typically
refers to the whole drive train, including gearbox, clutch, drive
shaft, differential and axles. In American usage for reciprocating
engines, the transmission is often taken to be the gearbox between
the clutch assembly in the bell housing and the drive shaft. The
more general definition is used herein (power transmission
apparatuses from the output shaft of an engine to a drive shaft)
unless specifically defined otherwise.
[0060] A traction motor is a motor used primarily for propulsion
such as commonly used in a locomotive. Examples are an AC or DC
induction motor, a permanent magnet motor and a switched reluctance
motor.
[0061] A turbine is any machine in which mechanical work is
extracted from a moving fluid by expanding the fluid from a higher
pressure to a lower pressure.
[0062] Turbine Inlet Temperature (TIT) as used herein refers to the
gas temperature at the outlet of the combustor which is closely
connected to the inlet of the high pressure turbine and these are
generally taken to be the same temperature.
[0063] A turbo-compressor spool assembly as used herein refers to
an assembly typically comprised of an outer case, a radial
compressor, a radial turbine wherein the radial compressor and
radial turbine are attached to a common shaft. The assembly also
includes inlet ducting for the compressor, a compressor rotor, a
diffuser for the compressor outlet, a volute for incoming flow to
the turbine, a turbine rotor and an outlet diffuser for the
turbine. The shaft connecting the compressor and turbine includes a
bearing system.
[0064] Any reference to a braking compressor is assumed to include
other dissipating apparatuses such as electric motors or other
mechanical, fluid, magnetic, electrical and/or electromagnetic
devices that consume energy.
[0065] The phrases "at least one", "one or more", and "and/or" are
open-ended expressions that are both conjunctive and disjunctive in
operation. For example, each of the expressions "at least one of A,
B and C", "at least one of A, B, or C", "one or more of A, B, and
C", "one or more of A, B, or C" and "A, B, and/or C" means A alone,
B alone, C alone, A and B together, A and C together, B and C
together, or A, B and C together.
[0066] The preceding is a simplified summary of the disclosure to
provide an understanding of some aspects of the disclosure. This
summary is neither an extensive nor exhaustive overview of the
disclosure and its various aspects, embodiments, and/or
configurations. It is intended neither to identify key or critical
elements of the disclosure nor to delineate the scope of the
disclosure but to present selected concepts of the disclosure in a
simplified form as an introduction to the more detailed description
presented below. As will be appreciated, other aspects,
embodiments, and/or configurations of the disclosure are possible
utilizing, alone or in combination, one or more of the features set
forth above or described in detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0067] The present disclosure may take form in various components
and arrangements of components, and in various steps and
arrangements of steps. The drawings are only for purposes of
illustrating the preferred embodiments and are not to be construed
as limiting the disclosure. In the drawings, like reference
numerals refer to like or analogous components throughout the
several views
[0068] FIG. 1 is a schematic of a prior art gas turbine engine
architecture.
[0069] FIG. 2 is a schematic of a gas turbine engine architecture
with a prior art braking compressor connected to a
transmission.
[0070] FIG. 3 is a schematic of a gas turbine engine architecture
with a prior art braking compressor connected to a free power
turbine.
[0071] FIG. 4 is a schematic of prior art control for a braking
compressor.
[0072] FIGS. 5a and 5b illustrate an example, in end view, of how a
braking compressor can be geared.
[0073] FIG. 6 illustrates an example, in plan view, of how a
braking compressor can be geared.
[0074] FIG. 7 illustrates an example, in plan view, of how a
braking compressor can be controlled using a Continuously Variable
Transmission ("CVT").
[0075] FIG. 8 illustrates in detail a braking compressor combined
with a high speed generator and thermal energy storage module.
[0076] FIG. 9 illustrates, in plan view, an example of how a
braking compressor can be used with a high speed generator and
thermal energy storage module.
[0077] FIG. 10 illustrates a brushless eddy current clutch with DC
excitation.
[0078] FIG. 11 illustrates a brushless eddy current clutch with AC
excitation.
[0079] FIG. 12 illustrates an example, in plan view, of how a
braking compressor can be controlled using an eddy current
clutch.
[0080] FIG. 13 illustrates a fluid pump circuit for dissipating
energy.
[0081] FIG. 14 is an isometric view of prior art planetary
gears.
[0082] FIGS. 15a and 15b illustrate how a planetary gear system can
be used for control of a braking compressor.
[0083] FIG. 16 illustrates an example, in plan view, of how a
braking compressor can be controlled using a fluid pump and
planetary gear system.
[0084] FIG. 17 is a schematic of a hybrid braking system for a gas
turbine engine.
[0085] FIG. 18 is a schematic of a first alternate hybrid braking
system for a gas turbine engine.
[0086] FIG. 19 is a schematic of a second alternate hybrid braking
system for a gas turbine engine.
[0087] FIGS. 20a and 20b are flow charts for free power turbine
over-speed control.
[0088] FIGS. 21a and 21b are flow charts for engine braking
control.
DETAILED DESCRIPTION
Prior Art
Preferred Engine
[0089] A preferred engine type is a high efficiency gas turbine
engine because it typically has lower NOx emissions, is more fuel
flexible, fuel tolerant and has lower maintenance costs. For
example, an intercooled recuperated gas turbine engine in the 10 kW
to 750 kW range is available with thermal efficiencies above 40%. A
schematic of an intercooled recuperated gas turbine engine is shown
in FIG. 1.
[0090] FIG. 1 is schematic of the component architecture of a prior
art multi-spool gas turbine engine. Air (or in some configurations,
an air-gaseous fuel mix) is ingested into a low pressure compressor
1. The outlet of the low pressure compressor 1 passes through an
intercooler 2 which removes a portion of heat from the gas stream
at approximately constant pressure. The gas then enters a high
pressure compressor 3. The outlet of high pressure compressor 3
passes through a recuperator 4 where a significant portion of the
heat from the exhaust gas is transferred, at approximately constant
pressure, to the gas flow from high pressure compressor 3. The
further heated gas from recuperator 4 is then directed to a
combustor 5 where a fuel is reacted or burned, adding a small mass
of fuel and substantial energy to the gas flow at approximately
constant pressure. The gas emerging from combustor 5 then enters a
high pressure turbine 6 where work is done by high pressure turbine
6 to operate high pressure compressor 3. The gas from high pressure
turbine 6 then enters a low pressure turbine 7 where work is done
by low pressure turbine 7 to operate low pressure compressor 1. The
gas from low pressure turbine 7 then enters a free power turbine 8.
The shaft of free power turbine 8, in turn, drives a transmission
11 which may be an electrical, mechanical or hybrid transmission
for a vehicle. Alternately, the shaft of the free power turbine can
drive an electrical generator or alternator. This engine design is
described, for example, in U.S. patent application Ser. No.
12/115,134 filed May 5, 2008, entitled "Multi-Spool Intercooled
Recuperated Gas Turbine", which is incorporated herein by this
reference.
[0091] Variations of this engine architecture may include a
reheater and/or thermal energy storage devices such as described,
for example, in U.S. patent application Ser. No. 13/175,564,
entitled "Improved Multi-Spool Intercooled Recuperated Gas Turbine"
and U.S. patent application Ser. No. 12/777,916, entitled "Gas
Turbine Energy Storage and Conversion System", both of which are
incorporated herein by reference.
Prior Art Engine Braking Using a Compressor
[0092] U.S. Pat. No. 3,817,343 entitled "Installation for Brake of
Motor Vehicles Which Are
[0093] Driven from a Gas Turbine" teaches a rotary compressor which
acts as a dissipating apparatus that can convert shaft power into
an air discharge by converting mechanical energy into kinetic and
heat energy of a gas, namely air. This apparatus can have utility
for braking systems on vehicles, especially large vehicles such as
Class 8 trucks. The dissipating compressor disclosed in U.S. Pat.
No. 3,817,343 does not teach how to control the braking force nor
does it teach how to utilize the energy dissipated by the braking
compressor.
[0094] Braking Compressor Locations
[0095] FIG. 2 is a schematic of a prior art gas turbine engine
architecture with braking compressor connected to a transmission.
The engine of FIG. 2 is identical to the engine shown in FIG. 1. A
braking compressor 12 is shown connected to a transmission 9 by
clutch apparatus 11. Transmission 9 connects the output shaft of
free power turbine 8 to the vehicle's drive shaft. The transmission
may be an electrical, mechanical or hybrid transmission.
Transmission 9 may be, for example, a mechanical transmission
appropriate to a reciprocating engine. If so, it can be adapted to
a gas turbine engine which may include a braking compressor
capability. This can be accomplished by adding a reducing gear
assembly to reduce rpms from the turbine output to the rpms of a
conventional transmission and a second clutch as described in FIG.
6. As can be appreciated, this configuration can be used on any
transmission with any engine. As will be discussed subsequently,
clutch 11 is optional. As can be appreciated, other dissipating
devices can be used in place of a braking compressor. These
include, for example, an electrical generator or a fluid pump
system.
[0096] FIG. 3 is a schematic of a prior art gas turbine engine
architecture with braking compressor connected to a free power
turbine. The engine of FIG. 3 is identical to that of FIG. 1. A
braking compressor 12 is shown connected to a free power turbine 8
by clutch apparatus 11. This configuration can be applied to a
vehicle with any type of transmission. This means of driving
braking compressor 12 is dependent on the packaging of the gas
turbine engine components. For example, if the low pressure turbine
outlet is connected directly to the free power turbine inlet, it
may be preferable to use the arrangement shown in FIG. 2. As will
be discussed subsequently, clutch 11 is optional.
Control of Braking Compressor Air Flow
[0097] FIG. 4 is a schematic of prior art control for a braking
compressor. In FIG. 4a, a braking compressor 12 is shown connected
to a transmission 9 by a clutch assembly 11. There is an inlet air
flow control device 13 to control the flow of inlet air 15 and an
outlet air flow control device 14 to control the flow of outlet air
16. The braking compressor 12 may have either an inlet air flow
control device 13 or an outlet air flow control device 14 or both.
The inlet air flow device may be a valve, a variable position
nozzle or the like. If there is only an inlet air flow control
device, then there would have to be a throat on the outlet of the
braking compressor to allow pressure buildup so that the compressor
could extract energy. The outlet air flow device may be a valve, a
variable position nozzle, an iris opening plate, a venturi throat
or the like. If there is only an outlet air flow control device,
then there may or may not be an inlet air flow control device. The
control of the braking compressor is such that surge and stall of
the compressor are avoided.
[0098] In FIG. 4b, a braking compressor 12 is shown connected to a
free power turbine 8 by a clutch assembly 11. There is an inlet air
flow control device 13 to control the flow of inlet air 15 and an
outlet air flow control device 14 to control the flow of outlet air
16. The braking compressor 12 may have either an inlet air flow
control device 13 or an outlet air flow control device 14 or both.
The inlet air flow device may be a valve, a variable position
nozzle or the like. If there is only an inlet air flow control
device, then there would have to be a throat on the outlet of the
braking compressor to allow pressure buildup so that the compressor
could extract energy. The outlet air flow device may be a valve, a
variable position nozzle, an iris opening plate, a venturi throat
or the like. If there is only an outlet air flow control device,
then there may or may not be an inlet air flow control device. The
control of the braking compressor is such that surge and stall of
the compressor are avoided.
Present Disclosure
[0099] In this disclosure, a braking compressor is often used to
illustrate a braking device that can dissipate energy either from
an over-speeding free turbine or to provide the effect of engine
braking. As can be appreciated, other dissipating apparatuses can
be used to dissipate energy either from an over-speeding free
turbine or to provide the effect of engine braking. These include
electric generators, pump systems, eddy current brakes and clutches
or other mechanical, fluid, magnetic, electrical and/or
electromagnetic devices that consume energy.
[0100] The method and apparatus of the present disclosure can be
adapted to either a vehicle powered by a gas turbine engine, by a
reciprocating piston engine or indeed any engine. If applied to an
engine running in the rpm range of 10,000 rpm or less, increasing
gears will normally be required to engage a braking compressor in
order for the braking power to be developed by an auxiliary
compressor which, for a reasonable size, will be more compact and
efficient at higher rpms, typically in the range of about 40,000
rpm to about 150,000 rpm.
[0101] An innovation of the present disclosure is the use of one or
more control devices and methods to control the amount of energy
dissipated by a braking compressor or other energy dissipating
braking device. As can be appreciated, it may be desirable to
dissipate large or small amounts of energy depending on the speed
of the vehicle and the desired braking force. Hard braking at high
speeds while going down hill can require large amounts of braking
energy to be dissipated by an engine braking system in addition to
that dissipated by the foundation braking system. Light braking at
low speeds can be provided by the foundation braking system or by
engine braking. The latter may be preferred since it may save undue
wear and tear on the foundation braking system.
[0102] Another advantage of these control methods is that they may
be used to route some of the engine braking energy to energy
storage devices rather than simply dissipating this energy.
[0103] Such control devices disclosed herein include (1) a
continuously variable transmission ("CVT"); (2) an electrical
generator and an optional thermal storage device; (3) an eddy
current clutch; and (4) a fluid pump system. The control devices
can be operated automatically by a computer to provide the desired
amount of braking force, for example, in response to the vehicle
operator depressing a brake petal. In the case of the electrical
generator or fluid pump system, these may be used both to dissipate
braking energy as well as control the amounts and rate of braking
energy dissipation.
[0104] Additional innovations disclosed herein include vehicle
braking systems that utilize some or all the braking features to
recoup a portion of braking energy available with either or both of
a hybrid transmission and an energy dissipating braking
apparatus.
[0105] In the present disclosure relating to a braking compressor,
attention will be focused on the design of subsonic compressors.
The braking compressor of the present disclosure can be a single
centrifugal compressor, a two-stage centrifugal compressor, or a
centrifugal and axial compressor combination. As an example,
consider a vehicle with a 375 kW engine. In order to provide
significant engine braking, a braking compressor would have to
dissipate power in the range of about 150 kW to about 400 kW. To
achieve this range of power dissipation in a compact apparatus, a
compressor system capable of a pressure ratio in the range of about
6:1 to about 12:1 would normally be required.
Gear Configurations and Ratios
[0106] FIG. 5 illustrates an example, in end view, of how a braking
compressor or other engine braking apparatus can be geared for the
configuration of FIG. 3 (braking compressor associated with the
free power turbine). As shown in FIG. 5a, high speed pinion 43
drives a high speed bull gear 41 where high speed pinion 43 is
attached to the shaft of a free power turbine. The typical
reduction between high speed pinion 43 and high speed bull gear 41
is commonly in the range of about 2:1 to about 10:1 and more
commonly in the range of about 4:1 to about 7:1. Another pinion 45
is attached to high speed bull gear 41 and drives low speed bull
gear 42. The typical reduction between high speed bull gear 41 and
low speed bull gear 42 is commonly in the range of about 2:1 to
about 10:1 and more commonly in the range of about 4:1 to about
7:1. A shaft 46 attached to low speed bull gear 42 is connected to
a clutch and gear box as described in FIG. 6. A second high speed
pinion 44 drives a power take-off shaft which operates the braking
compressor or other dissipating apparatus of the present
disclosure. FIG. 5b illustrates the gear engagement of pinions 43
and 44 with bull gear 41. Similar tooth engagement applies to
pinion 45 and low speed bull gear 42. As can be appreciated the
specific gear configuration may be any type of gear such as, for
example, spur, helical, double helical, bevel or hypoid gears.
[0107] In the following, the present disclosure is illustrated for
a braking compressor. As can be appreciated, the same gearing and
control methods can be applied to other energy dissipating devices
such, as for example, an electrical generator or a fluid pump.
[0108] FIG. 6 illustrates an example, in plan view, of how a prior
art braking compressor (that is a braking compressor with an inlet
and/or outlet air flow control device) may be operated with a
mechanical transmission and a gas turbine engine. This figure shows
free power turbine 8 with its output shaft 61 driving a
transmission defined by boundary 9 (dashed lines) that transmits
power from output shaft 61 to drive shaft 52. Transmission
components located inside a bell housing are contained to the left
of boundary 10 (dash-dot line) and extending to the left edge of
transmission boundary 9. Free power turbine output shaft 61
includes a high speed pinion 43 which drives a high speed bull gear
41. Shaft 64 is attached to high speed bull gear 41 and includes a
pinion 45 that drives low speed bull gear 42. Shaft 65 is attached
to low speed bull gear 42 and to clutch assembly 51. Shaft 66
attaches the other side of clutch assembly 51 to gearbox 50 which
contains switchable gear sets that can provide multiple gear
ratios, with the ability to switch between them as speed varies.
This switching may be done manually or automatically and may
include the ability to provide forward and reverse directional
control. Gearbox 50 transmits power to drive shaft 52 which, in
turn, is attached to one or more differentials 53. Differentials 53
drive axles 54 which power wheels 55. This figure is an example of
how a gas turbine engine can be used with a mechanical transmission
to propel a vehicle. As part of the present disclosure, a power
take-off pinion 44 is attached to shaft 63 which is attached to a
second clutch assembly 11. Shaft 62 is attached to the other side
of clutch assembly 11 and to braking compressor 12. As can be
appreciated, braking compressor 12 can be replaced with any
dissipating apparatus such as, for example, an electrical motor
that dissipates energy at the required power. As can be further
appreciated, the energy from the dissipating apparatus can be
utilized for useful purposes. For example, if the dissipating
apparatus is a compressor, it can be used to charge a pneumatic
energy storage apparatus which can be used to energize a pneumatic
braking system. Alternately, for example, if the dissipating
apparatus is an electrical motor, it can be used to charge an
electrical energy storage system such as a battery pack, a
capacitor bank or a system of flywheels.
[0109] In normal driving mode, clutch assembly 51 is engaged so
that power from free power turbine 8 is transmitted to wheels 55 by
the drive train. Clutch assembly 51 may be disengaged when the
engine is idling or when the engine is turned off In normal driving
mode, clutch assembly 11 is usually disengaged. If free power
turbine 8 is sensed to be over-speeding, then clutch assembly 11
may be engaged to control free power turbine over-speeding by
extracting energy. Over-speeding can occur when the load on the
free power turbine is abruptly decreased or removed.
[0110] In braking mode, clutch assembly 51 may be engaged or
disengaged. In braking mode, when clutch assembly 51 is disengaged,
clutch assembly 11 may be engaged to prevent free power turbine
from over-speeding which can occur when the its load is abruptly
removed. In braking mode, when clutch assembly 51 is engaged,
clutch assembly 11 may be engaged to transmit braking energy back
through the drive train to the braking compressor, thereby
providing engine braking in the same way that a Jacobs brake
provides additional braking for a reciprocating engine.
[0111] It was stated previously that clutch assembly 11 may be
optional. With clutch assembly 11 disengaged, there is no parasitic
load on the free power turbine when braking compressor 12 is not
required. It is possible to eliminate clutch assembly 11 and use
the outlet nozzle of the braking compressor to control braking.
When not required, the outlet nozzle can be opened fully so that
there is substantially no load and therefore substantially no
energy extracted by the braking compressor. The rotor or rotors of
the braking compressor apparatus can be allowed to rotate with
substantially no pressure differential until braking is required
and this will result in a small parasitic load on the free power
turbine. For engine braking or control of free power turbine
over-speed, the outlet nozzle on the braking compressor can be
closed to extract energy at a selected rate with or without clutch
assembly 11 as part of the system. Eliminating clutch assembly 11
would result in a small parasitic load to the vehicles engine.
Thus, if overall engine and transmission efficiency are to be
optimized, then retaining clutch assembly 11 would be preferable,
especially if the vehicle is a long haul vehicle.
[0112] As can be appreciated, a braking compressor can also be used
in conjunction with a hybrid transmission or an all electric
transmission. A hybrid transmission is considered to be a
transmission that can be operated as an electrical transmission or
a mechanical transmission, depending on vehicle speed. For example,
the free power turbine can drive an electrical generator and the
electrical generator can drive a traction motor. At higher speeds,
the electrical generator and traction motor can be locked up so
that the transmission becomes a purely mechanical transmission. For
any type of transmission, free power turbine 8 can be connected to
a pinion and bull gear arrangement such as pinions 43, 44 and bull
gear 41 to utilize a braking compressor for engine braking and free
power turbine over-speed control.
[0113] As can be appreciated, the amount of braking force supplied
by either or both of an inlet and outlet vanes of the braking
compressor may be controlled automatically by an appropriate
control algorithm which is responsive to the data from various
shaft rpms, free power turbine rpms and brake pedal force.
[0114] As will be described in FIGS. 7,9,12 and 16, FIG. 6 is the
basic transmission and gearing configuration for embodiments
wherein various innovative control apparatuses are used to modulate
braking compressor performance.
[0115] If a braking compressor is used, the output air from the
braking compressor can be discharged to the atmosphere, or it can
be used to charge a pneumatic storage tank, or it can be used for
quenching hot recuperator gases to assist in engine turndown. In
the latter case, as the vehicle is braking, the cool output air
from the braking compressor can be injected into the exhaust flow
upstream of the entrance to the hot side of the recuperator (see
FIG. 1 for an example of a recuperated gas turbine engine). This
will rapidly lower the temperature of the hot side recuperator air
and consequently reduce the energy transferred from the recuperator
hot side to the recuperator cold side. Since the rate of fuel
injection is usually reduced during braking, the combined effect of
fuel reduction and lowered energy transfer through the recuperator
will more rapidly reduce the power output of the combustor. The net
effect will be to more rapidly slow down the downstream turbines,
including the free power turbine.
Control Using a Continuously Variable Transmission ("CVT")
[0116] FIG. 7 illustrates an example, in plan view, of how a
braking compressor can be controlled using a CVT. Depending on the
rpm capability of the CVT, the CVT may be connected to the braking
compressor via an increasing gear. The CVT is connected to the
power train by a clutch assembly. As is well-known, a CVT has a low
gear ratio and a high gear ratio with infinitely many ratios
in-between. The advantage of a CVT is the ability to keep the
braking compressor rpms in their desired range for all braking
conditions. The free power turbine, the apparatuses contained
within the transmission, the drive shaft, differential and wheels
are the same as those of FIG. 6. As part of the present disclosure,
a power take-off pinion 44 is attached to shaft 63 which is
attached to a second clutch assembly 11. Shaft 62 is attached to
the other side of clutch assembly 11 and to the input side of CVT.
The output side of CVT 15 is shown attached to an increasing
gearbox 16 by shaft 67. Gearbox 16 is then attached to a braking
compressor 12 by shaft 68. If the rpm range of the CVT is high
enough, increasing gearbox 16 may not be required. As can be
appreciated, braking compressor 12 can be replaced with any
dissipating apparatus such as an electrical motor that dissipates
energy at the required power level. As can be further appreciated,
the energy from the dissipating apparatus can be utilized for
useful purposes. For example, if the dissipating apparatus is a
compressor, it can be used to charge a pneumatic energy storage
apparatus which can be used to energize a pneumatic braking system.
Alternately, for example, if the dissipating apparatus is an
electrical motor, it can be used to charge an electrical energy
storage system such as a battery pack, a capacitor bank or a system
of flywheels.
[0117] In normal driving mode, clutch assembly 51 is engaged so
that power from free power turbine 8 is transmitted to wheels 55 by
the drive train. Clutch assembly 51 may be disengaged when the
engine is idling or when the engine is turned off. In normal
driving mode, clutch assembly 11 is usually disengaged. If free
power turbine 8 is sensed to be over-speeding, then clutch assembly
11 may be engaged to control free power turbine over-speeding by
extracting energy. Over-speeding can occur when the load on the
free power turbine is abruptly decreased or removed. The CVT may be
controlled to provide a light to heavy braking action by
continuously varying the CVT gear ratio as described below.
[0118] In braking mode, clutch assembly 51 may be engaged or
disengaged. In braking mode, when clutch assembly 51 is disengaged,
clutch assembly 11 may be engaged to prevent free power turbine
from over-speeding which can occur when the load is abruptly
removed. In braking mode, when clutch assembly 51 is engaged,
clutch assembly 11 may be engaged to transmit braking energy back
through the drive train to the braking compressor via CVT 15,
thereby providing a continuously variable engine braking in the
same way that a Jacobs brake provides such braking for a
reciprocating engine. The increasing gearbox may be optional and is
typically used to provide higher compressor rpms and additional
braking energy at low speeds.
[0119] Consider the schematic of FIG. 7 for the example of a gas
turbine engine with an approximate peak output shaft power of about
350 kW. Such an engine might be operated at a high speed road power
output of about 175 kW to about 275 kW. Typical free power turbine
8 rotor speed is in the range of about 80,000 to about 120,000
rpms. The pinion 43 to bull gear 41 gear ratio may be approximately
7:1 so that shaft 64 rotates in the range of about 10,000 to about
12,500 rpms. The pinion 45 to bull gear 42 gear ratio may be also
approximately 7:1 so that shaft 65 and 66 when engaged rotates in
the range of about 1,250 to about 1,560 rpms.
[0120] A CVT has a low gear ratio and a high gear ratio with
infinitely many ratios in-between. For example, the lowest gear
ratio may be 0.2:1 and the highest about 1.2:1. Thus the total
range of gear ratios is about 6:1 from lowest to highest.
[0121] Consider a large vehicle at a speed of about 70 mph. The
wheel axles 54 would rotate at 588 rpms for a 40-inch wheel
diameter. With a differential gear ratio of 3, the main drive shaft
52 would rotate at 1,765 rpms. In high gear (1:1), shaft 64 would
rotate at 12,353 rpms and shaft 62 at 86,471 rpms. If CVT 15 is in
its lowest gear setting (0.2:1), then shaft 67 rotates at 17,394
rpms. If gear box 16 is set at 2:1, then the braking compressor
would rotate at 34,588 rpms which would be considered light
braking.
[0122] Now consider the same vehicle at a speed of about 10 mph.
The wheel axles 54 would rotate at 84 rpms. The main drive shaft 52
would rotate at 252 rpms. In low gear (4:1), shaft 64 would rotate
at 7,059 rpms and shaft 62 at 49,412 rpms. If CVT 15 is in its
highest gear setting (1.2:1), then shaft 67 rotates at 59,294 rpms.
If gear box 16 is set at 2:1, then the braking compressor would
rotate at 118,589 rpms which would be considered heavy braking.
[0123] As can be appreciated, the gear settings may be controlled
automatically by an appropriate control algorithm which is
responsive to the data from various shaft rpms, free power turbine
rpms and brake pedal force.
[0124] Control Using a Electrical Generator and Thermal Energy
Storage Module
[0125] FIG. 8 illustrates in detail a braking compressor combined
with a high speed electrical generator and thermal energy storage
module. Shaft 67 rotates generator 19 which rotates shaft 68. Shaft
68 drives braking compressor 12 which has an air inlet path 101 and
a compressed air output path 102. A thermal energy storage ("TES")
unit 72 is located in the discharge high-velocity air stream on the
output side of braking compressor 12. Such a thermal energy storage
device is described in U.S. patent application Ser. No. 12/777,916,
entitled "Gas Turbine Energy Storage and Conversion System" which
is incorporated herein by reference. Electrical generator 19 may be
engaged to generate a selected amount of electrical energy by means
of its control excitation to provide a selected amount of
retardation force on the rpms of shafts 67 and 68. The electrical
current output by generator 19 is carried via conductive path 77
and dissipated in TES unit 72 where a grid of wires is heated via
Joule heating. The heat energy generated in the wire grid is
carried away in the high velocity output air stream 102. As can be
appreciated, the electrical energy generated by generator 19 can be
re-directed to charge a battery or to a TES device located inside
the pressure boundary of the gas turbine engine as described in
U.S. patent application Ser. No. 12/777,916. The system described
in FIG. 8 can provide a higher retarding force than the compressor
alone and can provide control of the rpms and hence the amount of
energy dissipated by braking compressor 12. Electrical generator 19
may be a brushless alternator to avoid the need for rotating
electrical connections.
[0126] In this example, the discharge air from braking compressor
12 is used to dissipate heat stored in TES unit 72. As can be
appreciated, the electrical energy from generator 19 may be
dissipated by other means such as, for example, a dynamic braking
grid located elsewhere on the vehicle and whose energy can be
dissipated by air flow past the vehicle.
[0127] In the configuration of FIG. 9, the generator 19, when
excited, can be operated to apply additional braking torque to
shaft 67. The generator can also be driven in parallel to braking
compressor 12 as described for another control device in FIG.
16.
[0128] FIG. 9 illustrates an example, in plan view, of how a
braking compressor can be controlled using a high speed generator
and thermal energy storage module. Depending on the rpm capability
of the high speed generator, the high speed generator may be
connected to the braking compressor via an increasing gear. The
high speed generator is connected to the power train by a clutch
assembly.
[0129] In the example of FIG. 9, an electric generator that uses
field coils rather than permanent magnets is depicted. This type of
generator requires a current to be present in the field coils for
the device to be able to produce a retarding torque. If the field
coils are not powered, the rotor in the generator can spin without
producing any output electrical energy. As is well-known, this type
of high speed generator has a wide range of electrical output
depending on the level of excitation applied. The advantage of the
high speed generator is its ability to increase the amount of
braking force by generating while the braking compressor is
operative. The free power turbine, the apparatuses contained within
the transmission, the drive shaft, differential and wheels are the
same as those of FIG. 6. As part of the present disclosure, a power
take-off pinion 44 is attached to shaft 63 which is attached to a
second clutch assembly 11. Shaft 62 is attached to the other side
of clutch assembly 11 and to the input side of the high speed
generator 19. The output side of high speed generator 19 is
attached to a braking compressor 12 by shaft 68. As can be
appreciated, the electrical output of the high speed generator 19
can be utilized for useful purposes. For example, electrical output
of the high speed generator 19 can be used to charge an electrical
energy storage system such as a battery pack, a capacitor bank or a
system of flywheels.
[0130] In normal driving mode, clutch assembly 51 is engaged so
that power from free power turbine 8 is transmitted to wheels 55 by
the drive train. Clutch assembly 51 may be disengaged when the
engine is idling or when the engine is turned off In normal driving
mode, clutch assembly 11 is usually disengaged. If free power
turbine 8 is sensed to be over-speeding, then clutch assembly 11
may be engaged to control free power turbine over-speeding by
extracting energy. Over-speeding can occur when the load on the
free power turbine is abruptly decreased or removed. The high speed
generator 19 may be controlled to provide a light to heavy braking
action by continuously varying the applied excitation.
[0131] In braking mode, clutch assembly 51 may be engaged or
disengaged. In braking mode, when clutch assembly 51 is disengaged,
clutch assembly 11 may be engaged to prevent free power turbine
from over-speeding which can occur when the load is abruptly
removed. In braking mode, when clutch assembly 51 is engaged,
clutch assembly 11 may be engaged to transmit braking energy back
through the drive train to the braking compressor via the high
speed generator 19, thereby providing a continuously variable
engine braking force in the same way that a Jacobs brake provides
such braking for a reciprocating engine. An increasing gearbox
between the high speed generator and the braking compressor may be
used if the rpm capability of the high speed generator is too
low.
[0132] As can be appreciated, the thermal energy storage module
need not be present, especially if the electrical output of the
high speed generator is used to provide auxiliary power, charge an
energy storage system or if a dynamic braking grid already
exists.
[0133] As can be appreciated, the amount of excitation applied to
the electrical generator may be controlled automatically by an
appropriate control algorithm which is responsive to the data from
various shaft rpms, free power turbine rpms and brake pedal
force.
[0134] As can be further appreciated, the braking compressor 12 can
be eliminated and generator 19 can be used as the energy
dissipation device. Control of braking power and energy would be by
the amount of excitation applied to the generator. The output of
the generator can be re-directed to charge a battery or to a TES
device located inside the pressure boundary of the gas turbine
engine or to a dynamic braking grid.
[0135] Control Using an Eddy Current Clutch Assembly
[0136] Eddy current clutches are well-known. The following is an
innovative approach to an eddy current clutch based on a brushless
alternator. A brushless alternator is composed of two alternators
built end-to-end on one shaft. FIG. 10 illustrates an example of a
brushless eddy current clutch assembly with DC excitation. This is
an apparatus that can be used to provide a clutching function
between a vehicle's drive train and a braking apparatus such as a
braking compressor, in order to activate an engine braking
function. For example, the brushless eddy current clutch assembly
of FIG. 10 can be the clutch assembly 11 in FIG. 6. The control
function of the brushless eddy current clutch assembly of FIG. 10
can therefore be understood in relation to the engine braking role
of clutch assembly 11 in FIG. 6. As shown in FIG. 10, the input is
shaft 1 which rotates when the free power turbine (such as shown in
FIG. 6) rotates. Input shaft 1 is mechanically connected to exciter
armature 3 which, in turn is mechanically connected to diode board
4 which is, in turn, mechanically connected main field coil 5.
Exciter armature 3 is electrically connected to diode board 4 by 3
phase AC wires 12 and diode board 4 is electrically connected to
main field coil 5 by DC wires 13. Exciter armature 3, diode board 4
and main field coil 5 all rotate when input shaft 1 rotates. When
there is no excitation field in exciter field coil 2, then there is
no field generated in main field coil 5 and the main armature 6
does not rotate. Since main armature 6 is mechanically connected to
housing 10 which is mechanically connected to output shaft 7, there
is no rotation of output shaft 7 when there is no exciter field.
Exciter field coil 2 is mechanically mounted in housing 8 which is
fixed in position with respect to the free power turbine. The
exciter field can be activated by variable DC control system 11
which can provide a selected amount of DC current to stationary
exciter field coil 2.
[0137] As the DC current in exciter field coil 2 is increased, an
AC current is induced in rotating exciter armature 3. This AC
current is rectified in diode board 4 and causes a DC current in
main field coil 5. The DC current in main field coil 5 then induces
eddy currents in main armature 6. Main armature 6 may be a wound
coil or it may be a solid block of conductor (for example aluminum
which is an excellent conductor and is low density). The eddy
currents induced in main armature 6 cause a rotational force in
main armature 6 which tends rotate main armature 6 so as to reduce
these eddy currents. As main armature 6 rotates, its housing 10 and
hence output shaft 7 rotate with it. As the current in exciter
field coil 2 is increased further, main armature 6 which is
connected to housing 10 and output shaft 7 rotates faster and
faster until it is rotating almost as fast as input shaft 1.
Typically the output shaft can be caused to rotate within a few
percent of the rotation speed of the input shaft. Thus by varying
the DC control 11, the slippage between the input and output shaft
can be varied between full disengagement to almost complete lock-up
(1 or 2% slippage).
[0138] It is also possible to reverse the generator of FIG. 10 so
that shaft 7 is the input shaft from the drive train and shaft 1 is
the output shaft to the braking compressor. FIG. 11 illustrates an
example of a brushless eddy current clutch assembly with AC
excitation. The mechanical and electrical connections are the same
as those of FIG. 10. However, the DC excitation control is replaced
by an AC excitation control. When there is no excitation current,
then only shaft 7, housing 10 and main armature 6 rotate. When an
AC field in exciter field is applied in coil 2, this will induce a
field in exciter armature 3 and this will be rectified by diode
board 4 and create a DC current in main field coil 5. The rotation
of main armature 6 will then cause eddy currents to flow in main
armature 6 and this will cause a rotational torque in main field
coil 5 which will rotate shaft 1. Once the rotation of shaft 1
begins, the AC input to exciter field coil 3 can be controlled by
an appropriate algorithm to regulate the degree of clutch
engagement required.
[0139] FIG. 12 illustrates an example, in plan view, of how a
braking compressor can be controlled using an eddy current clutch
assembly. Depending on the rpm capability of the eddy current
clutch assembly, one side of the eddy current clutch is connected
to the braking compressor via an increasing gear. The other side of
the eddy current clutch is connected to the power train. As is
well-known, an eddy current clutch assembly has a continuously
variable range of clutching action from zero engagement to almost
totally locked (a small amount of residual slippage in the range of
about 1 or 2% from being fully locked), depending on the current
controlling the clutch. The advantage of an eddy current clutch
assembly is that it performs the function of a clutch and as well
as a control device to keep the braking compressor rpms in their
desired range for all braking conditions. The free power turbine,
the apparatuses contained within the transmission, the drive shaft,
differential and wheels are the same as those of FIG. 6. As part of
the present disclosure, a power take-off pinion 44 is attached to
shaft 63 which is attached to eddy current clutch assembly 11.
Shaft 67 is attached to the other side of eddy current clutch
assembly 11 and to the input side of an increasing gearbox 16.
Gearbox 16 is then attached to a braking compressor 12 by shaft 68.
As can be appreciated, braking compressor 12 can be replaced with
any dissipating apparatus such as an electrical motor that
dissipates energy at the required power. As can be further
appreciated, the energy from the dissipating apparatus can be
utilized for useful purposes. For example, if the dissipating
apparatus is a compressor, it can be used to charge a pneumatic
energy storage apparatus which can be used to energize a pneumatic
braking system. Alternately, for example, if the dissipating
apparatus is an electrical motor, it can be used to charge an
electrical energy storage system such as a battery pack, a
capacitor bank or a system of flywheels.
[0140] In normal driving mode, clutch assembly 51 is engaged so
that power from free power turbine 8 is transmitted to wheels 55 by
the drive train. Clutch assembly 51 may be disengaged when the
engine is idling or when the engine is turned off. In normal
driving mode, eddy current clutch assembly 11 is usually fully
disengaged. If free power turbine 8 is sensed to be over-speeding,
then eddy current clutch assembly 11 may be partially or fully
engaged to control free power turbine over-speeding by extracting
energy. Over-speeding can occur when the load on the free power
turbine is abruptly decreased or removed. The eddy current clutch
assembly may be controlled to provide a light to heavy braking
action by continuously varying the current to the eddy current
clutch assembly.
[0141] In braking mode, clutch assembly 51 may be engaged or
disengaged. In braking mode, when clutch assembly 51 is disengaged,
eddy current clutch assembly 11 may be engaged to prevent free
power turbine from over-speeding which can occur when the load is
abruptly removed. In braking mode, when clutch assembly 51 is
engaged, eddy current clutch assembly 11 may be fully or partially
engaged to transmit braking energy to the braking compressor,
thereby providing a continuously variable engine braking in the
same way that a Jacobs brake provides such braking for a
reciprocating engine. The increasing gearbox may be optional and is
typically used to provide higher compressor rpms and additional
braking energy at low speeds, depending on the rpm range of the
eddy current clutch system.
[0142] As can be appreciated, the degree of engagement of the eddy
current clutch assembly may be controlled automatically by an
appropriate control algorithm which is responsive to the data from
various shaft rpms, free power turbine rpms and brake pedal
force.
Control Using a Fluid Pump Circuit
[0143] FIG. 13 illustrates a fluid pump circuit for dissipating
energy for the fluid pump described in FIG. 16. This figure shows
an oil pump 1 whose throughput is controlled by restrictor valve 2.
The resistance to pump 1 is provided by restrictor valve 2 which,
as it is controlled to restrict the flow of oil, can increase the
temperature of the oil and cause the pump to work harder. The work
done by the pump and the heating of the oil are the mechanisms for
energy dissipation of the pump system. As is appreciated, the
viscosity of the heated oil will in general will be reduced and the
restrictor valve will have to be closed further to compensate for
this effect while increasing the work done by the pump.
[0144] The heated oil is subsequently cooled in heat exchanger 3
and returned to oil reservoir 4. Thus by controlling the flow
restriction provided by valve 2, the amount of work required by
pump 1 can be controlled. The advantage of this system, in addition
to providing additional engine braking power and/or controlling the
rpms of the braking compressor, is that it can be formed by
components already existing in the engine's oil lubrication system.
For example, the heat exchanger for cooling the oil and the
reservoir can be pre-existing components of an engine lubricating
system.
[0145] FIG. 14 is an isometric view of prior art planetary gear
set. This figure illustrates a typical three planet gear planetary
gear set. In the application described in FIG. 16, the braking
compressor is driven by the high-speed sun pinion. The input to the
planetary gear is from the vehicle's transmission through a low
speed bull gear and pinion gear as described in FIG. 16. Referring
to FIG. 15, the input to the planetary gear set can be from the
planet carrier or the ring (orbit) gear. The pump can be driven by
the planet carrier or the ring (orbit) gear while the braking
compressor is preferably driven by the sun pinion. As can be
appreciated, a planetary gear offers a variety of options depending
on the rpms required by the pump and braking compressor.
[0146] FIG. 15 illustrates an example of how a planetary gear
system can be used for control of a braking compressor. FIG. 15a
shows a head-on view of the output side of a planetary gear system.
Sun gear 1 is rotated by four planet gears 2, all of which are
attached to planet carrier 5. Planet gears 2 also engage teeth on
the inside of ring gear 3. Ring gear 3 also has teeth on its outer
side and these teeth engage spur gear 11. The output shaft of sun
gear 1 drives a braking compressor as described in FIG. 16. The
output shaft of spur gear 11 drives a fluid pump (or electrical
generator or eddy current brake) also as described in FIG. 16. FIG.
15 b shows a side view of a planetary gear system. Low speed input
shaft 6 rotates planet carrier 5 which rotates planet gears 2.
Planet gears 2 rotate sun gear 1 which drives output shaft 7 which
is connected to the braking compressor as described in FIG. 16.
Planet gears 2 engage the inside of ring gear 3. Spur gear 11
engages the outside of ring gear 3. The shaft of spur gear 11
drives shaft 8 which is connected to a fluid pump, electrical
generator, eddy current brake or any other suitable apparatus that
can apply a variable torque to ring gear 3.
[0147] FIG. 16 illustrates an example, in plan view, of how a
braking compressor can be controlled using a fluid pump and
planetary gear system. A fluid pump system 49 is connected to a
pinion gear 58 by shaft 59. Pinion gear 58 engages with gear teeth
on the outside of the ring gear of a planetary gear system 48. This
setup was described in more detail in FIG. 15. As can be
appreciated, fluid pump 49 may be an electrical generator or an
eddy current brake for example. The function fluid pump 49 is to
apply from zero to a maximum torque on planetary ring gear. If
fluid pump 49 applies no torque to the ring gear, then the ring
gear will free wheel and the sun gear will rotate slowly since the
input shaft 62 will rotate the planet carrier which will turn the
planetary gears at their minimum rotational speed. If fluid pump 49
applies maximum torque to the ring gear, then the ring gear will
tend to rotate slowly or not at all and the sun gear will rotate
rapidly since the input shaft 62 will rotate the planet carrier and
the planet gears will turn at their maximum rotational speed. As
can be appreciated, the rotation of the fluid pump shaft 59 can be
set up so that it can reverse the rotational direction of ring gear
58 which will cause the rotational speed of sun gear and shaft 68
to increase further. The free power turbine, the apparatuses
contained within the transmission, the drive shaft, differential
and wheels are the same as those of FIG. 6. As part of the present
disclosure, a power take-off pinion 44 is driven by low speed bull
gear 42. Pinion 44 is attached to shaft 63 which is attached to a
second clutch assembly 11. Shaft 62 is attached to the other side
of clutch assembly 11 and to the input side of the planetary gear
system 48. The input side of planetary gear system 48 rotates the
planetary carrier as described in more detail in FIG. 15. In this
configuration, the output of the planetary gear set is the sun
pinion which drives shaft 6 which is, in turn, connected to braking
compressor 12.
[0148] In normal driving mode, clutch assembly 51 is engaged so
that power from free power turbine 8 is transmitted to wheels 55 by
the drive train. Clutch assembly 51 may be disengaged to idle the
engine or when the engine is turned off. In normal driving mode,
clutch assembly 11 is usually disengaged. If free power turbine 8
is sensed to be over-speeding, then clutch assembly 11 may be
engaged to control free power turbine over-speeding by extracting
energy. Over-speeding can occur when the load on the free power
turbine is abruptly decreased or removed. The fluid pump 49 may be
controlled to provide a light to heavy braking action by
continuously varying the torque it applies to the outside of the
ring gear of the planetary gear system.
[0149] In braking mode, clutch assembly 51 may be engaged or
disengaged. In braking mode, when clutch assembly 51 is disengaged,
clutch assembly 11 may be engaged to prevent free power turbine
from over-speeding which can occur when the load is abruptly
removed. In braking mode, when clutch assembly 51 is engaged,
clutch assembly 11 may be engaged to transmit braking energy back
through the drive train to the braking compressor, with control of
the braking compressor rotational speed being provided by the
amount of torque applied to the ring gear of the planetary gear
system 48. This system thereby provides a continuously variable
engine braking in the same way that a Jacobs brake provides such
braking for a reciprocating engine. The drive input to the
planetary gear set is determined by the desired gear ratio to match
the rpm range of low speed bull gear 42 with the rpm range of the
sun pinion.
[0150] Consider an example of a planetary gear set with a sun
pinion having 30 teeth, four planet gears having 15 teeth each, and
the ring gear having 150 teeth on its inner ring. When the ring
gear is free wheeling, the sun gear rotates at 6 times the
rotational speed of the planet carrier. When the ring gear is fixed
and stationary, the sun gear rotates at 3 times the rotational
speed of the planet carrier. Thus by controlling the torque applied
to the outside of the ring gear by the fluid pump, the rotational
speed of the braking compressor can be varied by a factor of 2
which means its retarding force can be varied by the square of its
rotational speed or by a factor of 4.
[0151] A particular advantage of the configuration of FIG. 16 is
that the various gears in the transmission and the planetary gears
require lubrication and cooling. The oil pump can be used to
circulate oil in the vehicle's transmission gears as well as in the
planetary gears. The air expanded from the braking compressor can
be used to cool the planetary gear set as well as remove the heat
coming off the heat exchanger in the fluid pump circuit. When the
engine braking system is working, the resistance provided by the
oil pump is controlled by a restrictor valve as described in FIG.
12. This heats the oil beyond its normal operating temperature and
the air expanded from the braking compressor can be used to provide
cooling via the heat exchanger of FIG. 12 to maintain the oil at
its desired operating temperature. In this way, the engine braking
system of FIG. 16 can be configured to work with other engine
lubrication and cooling systems that are existing sub-systems of
the basic engine.
[0152] As can be appreciated, the degree of engagement of the fluid
pump applied to the outside of the ring gear be controlled
automatically by an appropriate control algorithm which is
responsive to the data from various shaft rpms, free power turbine
rpms and brake pedal force.
[0153] As can be further appreciated, the braking compressor 12 can
be eliminated and fluid pump 49 can be used as the energy
dissipation device. Control of braking power and energy would be by
the restrictor valve in the fluid circuit. As noted previously, the
work done by the pump and the heating of the oil are the mechanisms
for energy dissipation of the pump system.
Braking Systems for a Gas Turbine Engine
[0154] FIG. 17 is a schematic of a hybrid braking system for a gas
turbine engine. This figure illustrates a braking system for the
example of a gas turbine engine and braking compressor such as
shown in FIG. 3 with simple gearing for the braking as shown in
FIG. 6. As can be appreciated, other engine braking control
methods, such as shown in FIGS. 7, 9, 12 and 16 may be used. The
braking system shown in FIG. 17 includes a hybrid transmission 44
which can provide electric propulsive power transmission at low
speeds and direct mechanical propulsive power transmission at
higher speeds. Such hybrid transmissions are known and described,
for example, in U.S. patent application Ser. No. 12/777,916
entitled "Gas Turbine Energy Storage and Conversion System" and is
incorporated herein by reference.
[0155] In normal driving mode, clutch assembly 43 is engaged so
that power from free power turbine 8 is transmitted to the vehicles
wheels by the drive train. Clutch assembly 43 may be disengaged
when the engine is idling or when the engine is turned off. In
normal driving mode, clutch assembly 13 is usually disengaged. If
free power turbine 8 is sensed to be over-speeding, then clutch
assembly 13 may be engaged to control free power turbine
over-speeding by extracting energy by means of braking compressor
12. The compressed air provided by braking compressor 12 may be
discarded or it may be used to pressurize air reservoir 46 which is
part of a pneumatic braking system 45 for the vehicle. The
capability to provide compressed air as just described is
applicable to either a mechanical, hybrid or all-electrical
transmission.
[0156] In braking mode, clutch assembly 43 may be engaged or
disengaged. In braking mode, when clutch assembly 43 is disengaged,
clutch assembly 13 may be engaged to prevent free power turbine
from over-speeding which can occur when the its load is abruptly
removed. In braking mode, when assemblies 43 and 13 are engaged,
energy is transmitted to the braking compressor, thereby providing
engine braking in the same way that a Jacobs brake provides such
braking for a reciprocating engine. As can be appreciated, any of
the control devices disclosed herein (continuously variable
transmission; an electrical generator and a thermal storage device;
an eddy current clutch assembly; a fluid pump system; or any
combination of these) may be included with the braking compressor
for control purposes. If a hybrid or electrical transmission is
used, then electrical energy generated by braking may be used to
charge a battery or battery pack 12; heat a thermal storage element
13; operate pneumatic pump 47; and/or operate a control motor 10 on
the high pressure spool (comprised of compressor 3 and turbine 6)
or low the pressure spool (comprised of compressor 1 and turbine
7). Such a thermal energy storage device is disclosed in U.S.
patent application Ser. No. 12/777, 916 entitled "Gas Turbine
Energy Storage and Conversion System". Such a turbine spool control
motor is disclosed in U.S. patent application Ser. No. 13/175,564
entitled "Improved Multi-spool Intercooled Recuperated Gas Turbine"
and is incorporated herein by reference.
[0157] FIG. 18 is a schematic of a first alternate hybrid braking
system for a gas turbine engine. This figure illustrates a braking
system for the example of a gas turbine engine and braking
compressor such as shown in FIG. 3. As can be appreciated, other
engine braking control methods, such as shown in FIGS. 7, 9, 12 and
16 may be used. The braking system shown in FIG. 18 includes a
hybrid transmission 44 which can provide electric propulsion power
transmission at low speeds and direct mechanical propulsive power
transmission at higher speeds.
[0158] In normal driving mode, clutch assembly 43 is engaged so
that power from free power turbine 8 is transmitted to the vehicles
wheels by the drive train. Clutch assembly 43 may be disengaged
when the engine is idling or when the engine is turned off. In
normal driving mode, clutch assembly 13 is usually disengaged. If
free power turbine 8 is sensed to be over-speeding, then clutch
assembly 13 may be engaged to control free power turbine
over-speeding by extracting energy by means of braking compressor
12. The compressed air provided by braking compressor 12 may be
discarded or it may be used to pressurize air reservoir 46 which is
part of a pneumatic braking system 45 for the vehicle. The
capability to provide compressed air as just described is
applicable to either a mechanical, hybrid or all-electrical
transmission.
[0159] In braking mode, clutch assembly 43 may be engaged or
disengaged. In braking mode, when clutch assembly 43 is disengaged,
clutch assembly 13 may be engaged to prevent free power turbine
from over-speeding which can occur when the load is abruptly
removed. In braking mode, when clutch assemblies 43 and 13 are
engaged, energy is transmitted to the braking compressor, thereby
providing engine braking in the same way that a Jacobs brake
provides such braking for a reciprocating engine. This
configuration shows a control system described previously in FIG. 7
comprised of (a continuously variable transmission 25 and gearbox
26). If a hybrid or electrical transmission is used, then
electrical energy generated by braking may be used to charge a
battery or battery pack 12; heat a thermal storage element 13;
operate pneumatic pump 47; and/or operate a control motor 10 on the
high pressure spool (comprised of compressor 3 and turbine 6) or
low the pressure spool (comprised of compressor 1 and turbine
7).
[0160] FIG. 19 is a schematic of a second alternate hybrid braking
system for a gas turbine engine. This figure illustrates a braking
system for the example of a gas turbine engine and braking
compressor such as shown in FIG. 3. As can be appreciated, other
braking configurations, such as shown in FIGS. 7, 9, 12 and 16 may
be used. The braking system shown in FIG. 19 includes a hybrid
transmission 44 which can provide electric propulsion power
transmission at low speeds and direct mechanical propulsive power
transmission at higher speeds.
[0161] In normal driving mode, clutch assembly 43 is engaged so
that power from free power turbine 8 is transmitted to the vehicles
wheels by the drive train. Clutch assembly 43 may be disengaged
when the engine is idling or when the engine is turned off In
normal driving mode, eddy current clutch assembly 25 is usually
disengaged. If free power turbine 8 is sensed to be over-speeding,
then eddy current clutch assembly 25 may be engaged to control free
power turbine over-speeding by extracting energy by means of
braking compressor 12. The compressed air provided by braking
compressor 12 may be discarded or it may be used to pressurize air
reservoir 46 which is part of a pneumatic braking system 45 for the
vehicle. The capability to provide compressed air as just described
is applicable to either a mechanical, hybrid or all-electrical
transmission.
[0162] In braking mode, clutch assembly 43 may be engaged or
disengaged. In braking mode, when clutch assembly 43 is disengaged,
eddy current clutch assembly 25 may be engaged to prevent free
power turbine from over-speeding which can occur when the its load
is abruptly removed. In braking mode, when clutch assemblies 43 and
25 are engaged, energy is transmitted to the braking compressor,
thereby providing engine braking in the same way that a Jacobs
brake provides such braking for a reciprocating engine. This
configuration shows a control system described previously in FIG.
12 (an eddy current clutch assembly 25 and gearbox 26). If a hybrid
or electrical transmission is used, then electrical energy
generated by braking may be used to charge a battery or battery
pack 12; heat a thermal storage element 13; operate pneumatic pump
47; and/or operate a control motor 10 on the high pressure spool
(comprised of compressor 3 and turbine 6) or low the pressure spool
(comprised of compressor 1 and turbine 7). In addition, this
regenerative braking system can also use electrical energy derived
from braking to operate an electrolysis apparatus 51 which can
utilize the electrical energy of braking to produce hydrogen from
water stored in reservoir 52. The hydrogen produced can be stored
as a compressed gas or fed directly into the inlet air stream of
the gas turbine engine where it will react with available free
oxygen to provide additional energy to the engine thereby allowing
a reduction in primary fuel consumption. As can be appreciated, the
electrolysis apparatus can be a fuel cell operated in reverse. As
can also be appreciated, the electrolysis apparatus can be any
other apparatus for producing a fuel using electrical energy from
braking. For example, methane or methanol can be produced by a
reforming and water shift apparatus from a supply of contaminated
high carbon fuel such as dilbit (a mixture of bitumen and diluent
that may be high in vanadium content).
[0163] In the braking systems of FIGS. 17, 18 and 19, other
dissipating devices can be used in place of a braking compressor.
These include an electrical generator or a fluid pump system. The
braking compressor 12 can be eliminated and an electrical generator
can be used as the energy dissipation device. Control of braking
power and energy would be by the amount of excitation applied to
the generator. The output of the generator can be re-directed to
charge a battery or to a TES device located inside the pressure
boundary of the gas turbine engine or to a dynamic braking grid.
Alternately, the braking compressor 12 can be eliminated and fluid
pump can be used as the energy dissipation device. Control of
braking power and energy would be by the restrictor valve in the
fluid circuit. As noted previously, the work done by the pump and
the heating of the oil are the mechanisms for energy dissipation of
the pump system.
[0164] FIGS. 20a and 20b is a flow chart for free power turbine
over-speed control. Over-speed control can be implemented by an
on-board computer that automatically interrogates the appropriate
sensors, such as for example, free turbine rpms, the status or
on/off state of the engine braking clutch and the transmission
clutch, and control means for the braking device. In step 2001, the
free power turbine control routine is initiated. In step 2002, the
rpms of the free power are determined. In step 2003, if the rpms of
the free power are not excessive, then the free power turbine
control routine is terminated in step 2099. In step 2003, if the
rpms of the free power are determined to be excessive, then the
procedure moves to step 2004. If it is determined in step 2004 that
the engine braking clutch is not engaged, then the engine braking
clutch is engaged in step 2005 and the procedure moves to step
2006. If it is determined in step 2004 that the engine braking
clutch is engaged, then the procedure moves directly to step 2006.
If it is determined in step 2006 that the transmission clutch is
engaged, then the transmission clutch is disengaged in step 2007
and the procedure moves to step 2008. The transmission clutch is
disengaged since the rpms of the free power turbine would otherwise
be controlled by the speed of the vehicle if the transmission
clutch is engaged. The only effective way to reduce over-speed of
the free power turbine is to disengage the transmission clutch so
that the braking device can reduce the rpms of the free power
turbine without have to slow down the entire vehicle.
[0165] In step 2008, the amount of engine braking to reduce the
rpms of the free power turbine to acceptable levels is determined.
In step 2009, the amount of engine braking force to reduce the rpms
of the free power turbine to acceptable levels is applied by
controlling the amount of engine braking force applied by the
engine braking device. In step 2010, if the rpms of the free power
turbine are no longer excessive, then the braking clutch is
disengaged in step 2011 and the free power turbine control routine
is terminated in step 2099. In step 2010, if the rpms of the free
power are still determined to be excessive, then the procedure
moves to back to step 2008 where the amount of engine braking to
reduce the rpms of the free power turbine to acceptable levels is
again determined.
[0166] FIGS. 21a and 21b is a flow chart for engine braking
control. Engine braking control can be implemented by an on-board
computer that automatically interrogates the appropriate sensors,
such as for example, braking requests and free turbine rpms, the
status of the engine braking clutch and the transmission clutch,
and control means for the braking device. In step 2101, the engine
braking control routine is initiated. In step 2102, any engine
braking request is determined, for example, by sensing the motion
of a brake pedal or by a command to implement engine braking. If
there is no engine braking request or an engine braking is over
ridden (for example by a GPS monitor sensing a restricted area for
engine braking), the vehicle braking procedure is terminated in
step 2109. If a valid engine braking is request is determined in
step 2103 then the procedure moves to step 2104. If it is
determined in step 2104 that the transmission clutch is not
engaged, then the transmission clutch is engaged in step 22105 and
the procedure moves to step 2106 where the engine braking clutch is
engaged. If it is determined in step 2104 that the transmission
clutch is engaged, then the procedure moves directly to step 2106
where the engine braking clutch is engaged. In step 2107, the
amount of engine braking is determined. In step 2108, the selected
amount of engine braking is applied. In step 2109, if it is
determined that engine braking is no longer required, then the
braking clutch is disengaged in step 2110 and the engine braking
routine is terminated in step 2199. In step 2109, if it is
determined that engine braking is still required, then the
procedure moves to back to step 2107 where the amount of engine
braking is again determined.
[0167] The exemplary systems and methods of this disclosure have
been described in relation to preferred aspects, embodiments, and
configurations. Modifications and alterations will occur to others
upon a reading and understanding of the preceding detailed
description. It is intended that the disclosure be construed as
including all such modifications and alterations insofar as they
come within the scope of the appended claims or the equivalents
thereof. To avoid unnecessarily obscuring the present disclosure,
the preceding description omits a number of known structures and
devices. This omission is not to be construed as a limitation of
the scopes of the claims. Specific details are set forth to provide
an understanding of the present disclosure. It should however be
appreciated that the present disclosure may be practiced in a
variety of ways beyond the specific detail set forth herein.
[0168] Furthermore, while the exemplary aspects, embodiments,
and/or configurations illustrated herein show the various
components of the system collocated, certain components of the
system can be located remotely, at distant portions of a
distributed network, such as a LAN and/or the Internet, or within a
dedicated system. Thus, it should be appreciated, that the
components of the system can be combined in to one or more devices
or collocated.
[0169] Also, while the flowcharts have been discussed and
illustrated in relation to a particular sequence of events, it
should be appreciated that changes, additions, and omissions to
this sequence can occur without materially affecting the operation
of the disclosed embodiments, configuration, and aspects.
[0170] A number of variations and modifications of the disclosures
can be used. As will be appreciated, it would be possible to
provide for some features of the disclosures without providing
others.
[0171] The present disclosure, in various embodiments, includes
components, methods, processes, systems and/or apparatus
substantially as depicted and described herein, including various
embodiments, sub-combinations, and subsets thereof. Those of skill
in the art will understand how to make and use the embodiments,
aspects and configurations after understanding the present
disclosure. The present disclosure, in various embodiments,
includes providing devices and processes in the absence of items
not depicted and/or described herein or in various embodiments
hereof, including in the absence of such items as may have been
used in previous devices or processes, for example for improving
performance, achieving ease and\or reducing cost of
implementation.
[0172] The foregoing discussion of the disclosure has been
presented for purposes of illustration and description. The
foregoing is not intended to limit the disclosure to the form or
forms disclosed herein. In the foregoing Detailed Description for
example, various features of the disclosure are grouped together in
one or more embodiments for the purpose of streamlining the
disclosure. This method of disclosure is not to be interpreted as
reflecting an intention that the claimed disclosure requires more
features than are expressly recited in each claim. Rather, as the
following claims reflect, inventive aspects lie in less than all
features of a single foregoing disclosed embodiment. Thus, the
following claims are hereby incorporated into this Detailed
Description, with each claim standing on its own as a separate
preferred embodiment of the disclosure.
[0173] Moreover though the description of the disclosure has
included description of one or more embodiments and certain
variations and modifications, other variations and modifications
are within the scope of the disclosure, e.g., as may be within the
skill and knowledge of those in the art, after understanding the
present disclosure. It is intended to obtain rights which include
alternative embodiments to the extent permitted, including
alternate, interchangeable and/or equivalent structures, functions,
ranges or steps to those claimed, whether or not such alternate,
interchangeable and/or equivalent structures, functions, ranges or
steps are disclosed herein, and without intending to publicly
dedicate any patentable subject matter
* * * * *