U.S. patent application number 14/854319 was filed with the patent office on 2016-01-07 for integrated volumetric energy recovery and compression device.
The applicant listed for this patent is EATON CORPORATION. Invention is credited to William Nicholas BERGEN, Matthew James FORTINI.
Application Number | 20160003045 14/854319 |
Document ID | / |
Family ID | 50442742 |
Filed Date | 2016-01-07 |
United States Patent
Application |
20160003045 |
Kind Code |
A1 |
FORTINI; Matthew James ; et
al. |
January 7, 2016 |
Integrated Volumetric Energy Recovery and Compression Device
Abstract
Power-generation systems including a power plant and a power
conversion unit including an energy recovery device and volumetric
compressor are disclosed. In one embodiment, the volumetric fluid
compressor has first and second meshed rotors and is configured to
generate a stream of relatively high-pressure fluid including
oxygen to the power plant. In one embodiment, the volumetric fluid
energy recovery device having third and fourth meshed rotors,
operatively connected to the compressor, and configured to be
rotated by the exhaust gas or other fluid deriving energy from the
exhaust gas. The system can additionally include a set of timing
gears configured to operatively connect the first and second rotors
of the compressor to the third and fourth rotors of the energy
recovery device, and prevent contact between the first and second
rotors and between the third and fourth rotors. The system may also
include a rotation transferring link for operative connection
between the compressor and the energy recovery device.
Inventors: |
FORTINI; Matthew James;
(Allen Park, MI) ; BERGEN; William Nicholas;
(Harrison Twp., MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
EATON CORPORATION |
Cleaveland |
OH |
US |
|
|
Family ID: |
50442742 |
Appl. No.: |
14/854319 |
Filed: |
September 15, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/US2014/029223 |
Mar 14, 2014 |
|
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|
14854319 |
|
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61787834 |
Mar 15, 2013 |
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Current U.S.
Class: |
418/197 |
Current CPC
Class: |
F02B 37/12 20130101;
F01C 13/04 20130101; F01C 1/16 20130101; F01C 11/004 20130101; Y02T
10/12 20130101; F02B 33/38 20130101; Y02T 10/17 20130101; Y02T
10/144 20130101; F02B 33/36 20130101; F01C 1/126 20130101 |
International
Class: |
F01C 1/16 20060101
F01C001/16; F01C 13/04 20060101 F01C013/04; F01C 11/00 20060101
F01C011/00 |
Claims
1. An integrated compressor and expander system comprising: a fluid
compressor having first and second non-contacting helical meshed
rotors, wherein the first rotor is provided with a number of lobes
equal to a number of lobes provided on the second rotor; and a
volumetric energy recovery device having third and fourth
non-contacting helical meshed rotors, wherein the third rotor is
provided with a number of lobes equal to a number of lobes provided
on the fourth rotor; wherein the first and second rotors of the
volumetric fluid compressor are operably connected to the third and
fourth rotors of the volumetric energy recovery device such that
rotation of the third and fourth rotors causes rotation of the
first and second rotors.
2. The integrated compressor and expander system of claim 1,
wherein the first rotor and the third rotor are mounted to a common
shaft.
3. The integrated compressor and expander system of claim 1,
further comprising: a first shaft to which the first rotor is
mounted; a third shaft to which the third rotor is mounted; and a
power transmission link coupling the first shaft to the third
shaft.
4. The integrated compressor and expander system of claim 3,
wherein: the power transmission link includes a first transmission
gear mounted to the first shaft and a second transmission gear
mounted the third shaft.
5. The integrated compressor and expander system of claim 4,
wherein: the first transmission gear is meshed with the second
transmission gear.
6. The integrated compressor and expander system of claim 3,
wherein: the power transmission link includes a planetary gear set
including a ring gear, a sun gear mounted to the first shaft, and a
plurality of planet gears coupled to a common carrier mounted to
the third shaft.
7. The system of claim 6, further comprising a generator in
operative connection with the ring gear of the planetary gear set,
the generator being configured to vary a rotating speed of the
energy recovery device relative to a rotating speed of the
volumetric fluid compressor.
8. The system of claim 6, wherein the generator operates as a brake
to vary the rotating speed of the energy recovery device, and
wherein the volumetric energy recovery device freewheels when the
generator provides zero braking force, thereby reducing drag from
the volumetric energy recovery device on the volumetric fluid
compressor.
9. The system of claim 1, further comprising one of a pulley or a
gear drive configured to receive torque from a power source,
independent of the volumetric energy recovery device, to rotate the
volumetric fluid compressor.
10. The system of claim 9, further comprising an electric drive
unit configured to rotate the compressor.
11. A power-generation system comprising: a power plant employing a
power-generation cycle, wherein the power plant uses oxygen to
generate power and generates an exhaust gas as a byproduct of the
power-generation cycle; a volumetric fluid compressor having first
and second non-contacting meshed rotors and configured to generate
a stream of relatively high-pressure fluid including oxygen to the
power plant, wherein the first rotor is provided with a number of
lobes equal to a number of lobes provided on the second rotor; a
volumetric energy recovery device having third and fourth
non-contacting meshed rotors and configured to be rotated by the
exhaust gas to drive the compressor, wherein the third rotor is
provided with a number of lobes equal to a number of lobes provided
on the fourth rotor; and a power transmission link located between
the compressor and the energy recovery device, wherein the link is
configured to transfer torque generated by the energy recovery
device to the compressor.
12. The system of claim 11, wherein the power transmission link is
one of a gear set and a common shaft extending between the
volumetric fluid compressor and the volumetric energy recovery
device.
13. The system of claim 12, wherein the power plant is a fuel
cell.
14. The system of claim 12, wherein the power transmission link is
a gear set including a planetary gear structure.
15. The system of claim 14, wherein the gear set includes: first
and second timing gears fixed relative to the first and second
meshed rotors, respectively, configured to prevent contact between
the first and second rotors; and third and fourth timing gears
fixed relative to the third and fourth meshed rotors, respectively,
configured to prevent contact between the third and fourth rotors;
wherein the first and second timing gears are operatively connected
to the third and fourth timing gears via the planetary gear
structure.
16. The system of claim 15, further comprising a generator in
operative connection with the planetary gear structure and
configured to vary the rotating speed of the energy recovery device
to substantially match the rotating speeds of the power plant and
the energy recovery device.
17. The system of claim 16, wherein the generator operates as a
brake to vary the rotating speed of the energy recovery device, and
wherein the energy recovery device freewheels when the generator
provides zero braking force, thereby reducing drag from the energy
recovery device on the compressor.
18. The system of claim 17, wherein the power plant is an internal
combustion (IC) engine.
19. The system of claim 18, further comprising one of a pulley or a
gear drive configured to receive torque from the IC engine and
rotate the compressor.
20. The system of claim 11, further comprising an electric drive
unit configured to rotate the compressor.
21. A power conversion unit comprising: a power plant that receives
intake air and produces exhaust; a fluid compressor configured to
provide pressurized intake air to the power plant; an energy
recovery device coupled to the fluid compression device and being
configured to convert energy from the power plant exhaust to
rotational energy that drives the fluid compression device; a drive
system coupling the fluid compression device to a power output
location of the power plant, the drive system including a clutch to
selectively engage the fluid compression device with the power
plant power output location; and a compressor bypass valve
configured to recirculate the pressurized intake air from an outlet
of the fluid compressor to an inlet of the fluid compressor.
22. The power conversion unit of claim 21, wherein the power
conversion unit has at least a first operational mode and a second
operational mode: the first operational mode including the clutch
of the drive system being disengaged to decouple the fluid
compressor from the power plant power output location; and the
second operational mode including the clutch of the drive system
being engaged to couple the fluid compressor with the power plant
power output location.
23. The power conversion unit of claim 22, further including: an
exhaust bypass valve configured to allow at least a portion of the
power plant exhaust to bypass the energy recovery device, the
exhaust bypass valve being configured to maintain a differential
exhaust pressure set point across the energy recovery device;
24. The power conversion unit of claim 23, wherein: the first
operational mode further includes the exhaust bypass valve being in
an open position.
25. The power conversion unit of claim 22, wherein: the power
conversion unit is configured to transfer power from the energy
recovery device to the power plant power output location in the
first operational mode when the compressor bypass valve is fully
open.
26. The power conversion unit of claim 22, wherein: the compressor
bypass valve is configured to open when the power conversion unit
transitions from the second operational mode to the first
operational mode.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application is being filed on 14 Mar. 2014, as a PCT
International Patent application and claims priority to U.S. Patent
Application Ser. No. 61/787,834 filed on 15 Mar. 2013, the
disclosure of which is incorporated herein by reference in its
entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to a power-generation system
including a volumetric energy recovery device coupled to a power
plant.
BACKGROUND
[0003] Fluid devices, such as expansion turbines, are frequently
used to generate useful work in various power-generation processes.
In such power-generation processes a high pressure working fluid is
typically expanded in the fluid device to produce useful work.
Because the work is extracted from the expanding high pressure
fluid, the fluid expansion is approximated by an isentropic
process, i.e., a constant entropy process.
[0004] Representative power-generation processes may include the
Rankine cycle, where the working fluid may be water and the
combustion of natural gas, fuel oil or coal is used to generate
high-pressure steam to be subsequently channeled to the device.
After the energy of the high temperature working fluid has been
converted to useful work within the fluid device, the working fluid
is typically exhausted from the device in low pressure form at a
significantly reduced temperature, sometimes below -90.degree.
C.
SUMMARY
[0005] A power-generation system includes a power plant employing a
power-generation cycle, wherein the power plant uses oxygen to
generate power and generates an exhaust gas as a byproduct of the
power-generation cycle. The system can also include a volumetric
fluid compressor having first and second meshed rotors and
configured to generate a stream of relatively high-pressure fluid
including oxygen to the power plant. The system also may also
include a volumetric fluid energy recovery device having third and
fourth meshed rotors, operatively connected to the compressor, and
configured to be rotated by the exhaust gas, i.e., to recoup energy
from the exhaust gas, to drive the compressor. The system can
additionally include a set of timing gears configured to
operatively connect the first and second rotors of the compressor
to the third and fourth rotors of the energy recovery device, and
prevent contact between the first and second rotors and between the
third and fourth rotors. The system may also include a rotation
transferring link for operative connection between the compressor
and the energy recovery device. The link can be configured to
substantially match rotating speed of the energy recovery device
with the rotating speed of the power plant that is determined by an
amount of oxygen used by the power plant to generate the power.
[0006] Another embodiment of the disclosure is directed to a
vehicle having a power plant that employs a power-generation cycle
to propel the vehicle. The vehicle can include a volumetric fluid
compressor and a volumetric energy recovery device of the kind
described above.
[0007] The above features and advantages, and other features and
advantages of the present disclosure, will be readily apparent from
the following detailed description of the embodiment(s) and best
mode(s) for carrying out the described invention when taken in
connection with the accompanying drawings and appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a schematic depiction of a first embodiment of a
vehicle power plant having a volumetric energy recovery device and
a volumetric fluid compressor having features that are examples of
aspects in accordance with the principles of the present
disclosure.
[0009] FIG. 2 is a schematic depiction of a second embodiment of a
vehicle power plant having a volumetric energy recovery device and
a volumetric fluid compressor having features that are examples of
aspects in accordance with the principles of the present
disclosure.
[0010] FIG. 3 is a schematic depiction of a third embodiment of a
vehicle power plant having a volumetric energy recovery device and
a volumetric fluid compressor having features that are examples of
aspects in accordance with the principles of the present
disclosure.
[0011] FIG. 4 is a schematic depiction of a first embodiment of an
integrated device including a volumetric energy recovery device and
volumetric fluid compressor usable in the power plants of FIGS.
1-3.
[0012] FIG. 5 is a schematic depiction of a second embodiment of an
integrated device including a volumetric energy recovery device and
a volumetric fluid compressor usable in the power plants of FIGS.
1-3.
[0013] FIG. 5A is an end view of a planetary gear set usable in the
integrated device shown in FIG. 5.
[0014] FIG. 6 is a schematic cross-sectional side view of an energy
recovery device usable in the power plants of FIGS. 1-3, and
8-9.
[0015] FIG. 7 is schematic perspective view of an energy recovery
device usable in the power plants of FIGS. 1-3, and 8-9.
[0016] FIG. 8 is a schematic depiction of a fourth embodiment of a
vehicle power plant having a volumetric energy recovery device and
a volumetric fluid compressor having features that are examples of
aspects in accordance with the principles of the present
disclosure.
[0017] FIG. 9 is a schematic depiction of a fifth embodiment of a
vehicle power plant having a volumetric energy recovery device and
a volumetric fluid compressor having features that are examples of
aspects in accordance with the principles of the present
disclosure.
[0018] FIG. 10 is a schematic of a rotor geometry usable with the
energy recovery device shown in FIG. 6.
[0019] FIG. 11 is a schematic depiction of a third embodiment of an
integrated device including a volumetric energy recovery device and
a volumetric fluid compressor usable in the power plants of FIGS.
1-3.
DETAILED DESCRIPTION
[0020] Various embodiments will be described in detail with
reference to the drawings, wherein like reference numerals
represent like parts and assemblies throughout the several views.
Reference to various embodiments does not limit the scope of the
claims attached hereto. Additionally, any examples set forth in
this specification are not intended to be limiting and merely set
forth some of the many possible embodiments for the appended
claims.
[0021] Modern demands for fuel efficient vehicles and power plants
have led to development of hybrid power-generation and propulsion
systems. Generally, such systems combine a power plant, such as an
internal combustion engine or a fuel cell, and an electric motor to
drive the vehicle. Each of the internal combustion engine and fuel
cell emits high temperature exhaust as a byproduct of the
power-generation cycle employed therein. The high temperature
exhaust constitutes energy that is lost from the power-generation
cycle, which, if recaptured, could be employed to improve
efficiency of the cycle, and, therefore, of the propulsion system
employing the same.
[0022] Referring to the drawings wherein like reference numbers
correspond to like or similar components throughout the several
figures. Improvements in other applications are also desired, for
example in marine agricultural and industries. Another example is
stationary generator sets.
[0023] FIGS. 1-3 and 8-9 show examples of power-generation systems
14 that include a power conversion unit 15. Each of the disclosed
power conversion units 15 includes an energy recovery device 20 and
a compression device 50. As presented, the energy recovery device
20 converts waste heat energy from the power plant 16 to rotational
energy that can be utilized to drive the compression device 50
directly or indirectly. FIGS. 1-3 show examples of integrated power
conversion units 15 in which the energy recovery device 20 is
directly coupled to a compression device 50. By use of the term
"compression device" it is meant to include any type of device
capable of compressing a gas fluid stream, such as volumetric
devices (e.g. Roots-style blowers) and non-volumetric devices (e.g.
screw type compressors, turbines, scroll type compressors, etc.).
By use of the term "integrated" it is meant to include systems
where the output of the device 20 and the input for the compression
device 50 are mechanically coupled together. FIGS. 8-9 show
examples of distributed power conversion units 15 in which the
energy recovery device 20 and the compression device 50 are each
coupled to the power plant 16. By use of the term "distributed" it
is meant to include systems that do not share a direct mechanical
link between the device 20 and the compression device 50. The
power-generation systems 14 may be associated with a vehicle,
agricultural equipment, and/or stationary power generation systems,
such as generator sets.
[0024] Referring to FIG. 1, a vehicle 10 is shown having wheels 12
for movement along an appropriate road surface. The vehicle 10
includes a power-generation system 14. The system 14 includes a
power plant 16 employing a power-generation cycle. The power plant
16 uses a specified amount of oxygen, which may be part of a stream
of intake air 11, to generate power. The power plant 16 also
generates waste heat in the form of a high-temperature exhaust gas
in exhaust line 18. In one embodiment, the power plant 16 is an
internal combustion (IC) engine, such as a spark-ignition or
compression-ignition type which combusts a mixture of fuel and air
to generate power. In one embodiment, the power plant 16 may be a
fuel cell which converts chemical energy from a fuel into
electricity through a chemical reaction with oxygen or another
oxidizing agent.
[0025] In one embodiment, and as shown in FIG. 1, all of the
exhaust from power plant 16 is directed to the power conversion
unit 15 via exhaust line 18. As the exhaust passes through the
energy recovery side of the unit 15, the exhaust gas causes
internal rotors 30, 32 to rotate, which in turns causes internal
rotors 60, 62 of the compression device 50 to rotate. The gas can
then exit the system at exhaust line 17. As shown at FIG. 1, an
exhaust bypass line 18a and a bypass valve 202 are provided to
allow exhaust gases to be diverted around the energy recovery
device 20, when desired. The rotation of the rotors 60, 62 causes
an intake air stream 11 to be compressed and delivered to the power
plant 16 via intake manifold 13. As shown at FIG. 1, an intake air
bypass line 13a and bypass valve 204 may be provided to allow
compressed air to recirculate back to the compression device inlet
at line 11 in order to prevent over-compression of the intake air.
It is noted that the description of the energy recovery device 20
and the compression device 50 will be discussed in detail in later
sections, as will be the operation of the bypass valves 202 and
204.
[0026] In one embodiment, and as shown in FIG. 2, only a portion of
the exhaust from the power plant 16 is directed to the power
conversion unit 15 via exhaust line 18a. As shown, line 18a carries
exhaust gas that is to be recirculated into the intake manifold 13
of the power plant 16 in an exhaust gas recirculation (EGR)
configuration. Accordingly, after the exhaust passes through the
energy recovery device 20, the exhaust gas can be delivered to an
exhaust gas cooler 19 via line 18b and then provided to an EGR
mixer 21 via line 18c where the exhaust gas can be missed with
fresh intake air from compression device 50. It is noted that
energy recovery device 20 extracts energy from the exhaust gas
stream and can allow for the EGR cooler 19 to be made smaller than
might otherwise be possible without an energy recovery device 20.
The energy recovery device can also be used to regulate the amount
of EGR mixed into the fresh intake air. It is noted that the system
shown in FIG. 2 may also be provided with the bypass lines 13a
and/or 18a and the bypass valves 202 and/or 204 shown in FIG.
1.
[0027] In one embodiment, and as shown in FIG. 3, an organic
Rankine cycle (ORC) is used to power the energy recovery device 20
rather than exhaust gas directly. In such an embodiment, a piping
system 100 including a heat exchanger 102 is provided that
transfers heat from the exhaust gas line 18 to a working fluid that
is then delivered to the energy recovery device 20. A condenser 104
is also provided which creates a low pressure zone for the working
fluid and thereby provides a location for the working fluid to
condense. Once condensed, the working fluid can be delivered to the
heat exchanger 102 via a pump 106. A more detailed description of
an ORC system being utilized to drive an energy recovery device 20
is provided in Patent Cooperation Treaty (PCT) International
Application Number PCT/US13/28273 entitled VOLUMETRIC ENERGY
RECOVERY DEVICE AND SYSTEMS. PCT/US13/28273 is incorporated herein
by reference in its entirety. It is noted that the system shown in
FIG. 3 may also be provided with the bypass line 18a and the bypass
valve 202 shown in FIG. 1.
[0028] Referring to FIG. 8, an embodiment is shown in which the
compression device 50 and the energy recovery device 20 are
separate units and are therefore not integrated with each other.
Accordingly, compression device 50 may be a standard Roots-type
blower 50. In one embodiment, the compression device 50 is of the
type shown and described in U.S. Pat. No. 7,488,164 entitled
OPTIMIZED HELIX ANGLE ROTORS FOR ROOTS-STYLE SUPERCHARGER, which is
incorporated herein by reference in its entirety. In one
embodiment, the energy recovery device 20 is of the type shown and
described in the above referenced application PCT/US13/28273. As
shown, a power output location 16b of the power plant 16 drives the
compression device 50, while the output of the energy recovery
device 20 is sent to a power input location 16a of the power plant.
In one embodiment, the power input location 16a is the drive shaft
of the engine and the power output location 16b is a pulley, belt,
gear, or chain connected directly or indirectly to the power plant
16 crankshaft. Alternatively, or in addition to, the energy
recovery device can send power to an energy storage device 110,
such as a battery or accumulator. It is noted that the system shown
in FIG. 8 may also be provided with the bypass lines 13a and/or 18a
and the bypass valves 202 and/or 204 shown in FIG. 1.
[0029] FIG. 9 is similar to FIG. 8 in that a distributed system is
shown, but shows the use of two energy recovery devices 20A and
20B. The exhaust flow configuration for the first energy recovery
device 20A is the same as that shown for FIG. 2 while the exhaust
flow stream for the second energy recovery device 20B is the
exhaust flow not utilized in the EGR system. As shown, both the
energy recovery devices 20A, 20B provide power back to the power
plant 16 at a location 16a, which may be a common location or
separate locations. It is noted that the system shown in FIG. 9 may
also be provided with the bypass lines 13a and/or 18a and the
bypass valves 202 and/or 204 shown in FIG. 1.
[0030] Referring to FIGS. 4, 5, and 11, schematics of three
embodiments of an integrated power conversion unit 15, 115 usable
with the above described systems are shown. FIGS. 7 and 8 show
further details regarding the volumetric energy recovery device 20.
It is noted that many features of the volumetric energy recovery
device 20 are shared with the compression device 50.
Power Conversion Unit--Energy Recovery Device
[0031] In general, the volumetric energy recovery device 20 relies
upon the kinetic energy and static pressure of the working fluid
12-1 to rotate a shaft 38 or 40. Where the device 20 is used in an
expansion application, such as with a Rankine cycle, additional
energy is extracted from the working fluid via fluid expansion. In
such instances, device 20 may be referred to as an expander or
expansion device, as so presented in the following paragraphs.
However, it is to be understood that the device 20 is not limited
to applications where a working fluid is expanded across the
device, for example the exhaust driven embodiments shown in FIGS. 1
and 2.
[0032] The device 20 has a housing 22 with a fluid inlet 24 and a
fluid outlet 26 through which the working fluid 12-1 undergoes a
pressure drop to transfer energy to the shaft 38 or 40. The shaft
38 is driven by synchronously connected first and second
interleaved counter-rotating rotors 30, 32 which are disposed in a
cavity 28 of the housing 22. Each of the rotors 30, 32 has lobes
that are twisted or helically disposed along the length of the
rotors 30, 32. Upon rotation of the rotors 30, 32, the lobes at
least partially seal the working fluid 12-1 against an interior
side of the housing, at which point expansion of the working fluid
12-1 only occurs to the extent allowed by leakage which represents
an inefficiency in the system, in an ORC application. In contrast
to some expansion devices that change the volume of the working
fluid when the fluid is sealed, the volume defined between the
lobes and the interior side of the housing 22 of device 20 is
constant as the working fluid 12-1 traverses the length of the
rotors 30, 32. Accordingly, the device 20 may be referred to as a
"volumetric device" as the sealed or partially sealed working fluid
volume does not change. It is noted that, and as will be clear to
one skilled in the art upon learning of this disclosure, the
described geometry and construction of the device 20 is dissimilar
from the geometry and construction of a typical roots-type
compressor.
[0033] The device 20 is shown in detail in FIGS. 6 and 7. The
device 20 includes a housing 22. As shown in FIG. 6, the housing 22
includes an inlet port 24 configured to admit relatively
high-pressure working fluid 12-1 from the heat exchanger 102 (shown
in FIG. 3) or direct exhaust (FIGS. 1 and 2) from power plant 16.
The housing 22 also includes an outlet port 26 configured to
discharge working fluid 12-2. It is noted that the working fluid
discharging from the outlet 26 is at a relatively higher pressure
than the pressure of the working fluid at the condenser 104, where
an ORC system is utilized. Additionally, the inlet and outlet ports
24, 26 may be provided with connectors for providing a fluid tight
seal with other system components to ensure the working fluid 12-1,
12-2, which may be ethanol, does not dangerously leak outside of
the device 20.
[0034] As additionally shown in FIG. 7, each rotor 30, 32 has four
lobes, 30-1, 30-2, 30-3, and 30-4 in the case of the rotor 30, and
32-1, 32-2, 32-3, and 32-4 in the case of the rotor 32. Although
four lobes are shown for each rotor 30 and 32, each of the two
rotors may have any number of lobes that is equal to or greater
than two, as long as the number of lobes is the same for both
rotors. Accordingly, when one lobe of the rotor 30, such as the
lobe 30-1 is leading with respect to the inlet port 24, a lobe of
the rotor 30, such as the lobe 30-2, is trailing with respect to
the inlet port 24, and, therefore with respect to a stream of the
high-pressure working fluid 12-1.
[0035] As shown, the first and second rotors 30 and 32 are fixed to
respective rotor shafts, the first rotor being fixed to a shaft 38
and the second rotor being fixed to a shaft 40. Each of the rotor
shafts 38, 40 is mounted for rotation on a set of bearings (not
shown) about an axis X1, X2, respectively. It is noted that axes X1
and X2 are generally parallel to each other. The first and second
rotors 30 and 32 are interleaved and continuously meshed for
unitary rotation with each other. With renewed reference to FIG. 6,
the device 20 also includes meshed timing gears 42 and 44, wherein
the timing gear 42 is fixed for rotation with the rotor 30, while
the timing gear 44 is fixed for rotation with the rotor 32. The
timing gears 42, 44 are configured to retain specified position of
the rotors 30, 32 and prevent contact between the rotors during
operation of the device 20.
[0036] The shaft 38 is rotated by the working fluid 12-1 as the
working fluid transitions from the relatively high-pressure working
fluid 12-1 to the relatively low-pressure working fluid 12-2. As
may additionally be seen in both FIGS. 6 and 7, the shaft 38
extends beyond the boundary of the housing 22. Although the shaft
38 is shown as being operatively connected to the first rotor 30,
in the alternative the shaft 38 may be operatively connected to the
second rotor 32. As schematically shown in FIGS. 8-9, the shaft 38
can be coupled to the power plant 16 such that the energy from the
exhaust can be recaptured. A gear reducer can be provided to
provide a better match between rotational speeds of the power plant
16 and the shaft 38.
[0037] In one aspect of the geometry of the device 20, each of the
rotor lobes 30-1 to 30-4 and 32-1 to 32-4 has a lobe geometry in
which the twist of each of the first and second rotors 30 and 32 is
constant along their substantially matching length 34. As shown
schematically at FIG. 10, one parameter of the lobe geometry is the
helix angle HA. By way of definition, it should be understood that
references hereinafter to "helix angle" of the rotor lobes is meant
to refer to the helix angle at the pitch diameter PD (or pitch
circle) of the rotors 30 and 32. The term pitch diameter and its
identification are well understood to those skilled in the gear and
rotor art and will not be further discussed herein. As used herein,
the helix angle HA can be calculated as follows: Helix Angle
(HA)=(180/.pi.*arctan(PD/Lead)), wherein: PD=pitch diameter of the
rotor lobes; and Lead=the lobe length required for the lobe to
complete 360 degrees of twist. It is noted that the Lead is a
function of the twist angle and the length L1, L2 of the lobes 30,
32, respectively. The twist angle is known to those skilled in the
art to be the angular displacement of the lobe, in degrees, which
occurs in "traveling" the length of the lobe from the rearward end
of the rotor to the forward end of the rotor. As shown, the twist
angle is about 120 degrees, although the twist angle may be fewer
or more degrees, such as 160 degrees.
[0038] In another aspect of the expander geometry, the inlet port
24 includes an inlet angle 24-1, as can be seen schematically at
FIG. 6, and in the embodiments shown at FIGS. 4-5. In one
embodiment, the inlet angle 24-1 is defined as the general or
average angle of an inner surface 24a of the inlet port 24, for
example an anterior inner surface as shown at FIG. 6. In one
embodiment, the inlet angle 24-1 is defined as the angle of the
general centerline of the inlet port 24, for example as shown at
FIG. 2. In one embodiment, the inlet angle 24-1 is defined as the
general resulting direction of the working fluid 12-1 entering the
rotors 30, 32 due to contact with the anterior inner surface 24a,
as can be seen at both FIGS. 2 and 8. As shown, the inlet angle
24-1 is neither perpendicular nor parallel to the rotational axes
X1, X2 of the rotors 30, 32. Accordingly, the anterior inner
surface 24a of the inlet port 24 causes a substantial portion of
the working fluid 12-1 to be shaped in a direction that is at an
oblique angle with respect to the rotational axes X1, X2 of the
rotors 30, 32, and thus generally parallel to the inlet angle
24-1.
[0039] Furthermore, the inlet port 24 may be shaped such that the
working fluid 12-1 is directed to the first axial ends 30a, 30b of
the rotors 30, 32 and directed to the rotor lobe leading and
trailing surfaces (discussed below) from a lateral direction.
However, it is to be understood that the inlet angle 24-1 may be
generally parallel or generally perpendicular to axes X1, X2,
although an efficiency loss may be anticipated for certain rotor
configurations. Furthermore, it is noted that the inlet port 24 may
be shaped to narrow towards the inlet opening 24b, as shown in both
FIGS. 2 and 8. Referring to FIG. 10, it can be seen that the inlet
port 24 has a width W that is slightly less than the combined
diameter distance of the rotors 30, 32. The combined rotor diameter
is equal to the distance between the axes X1 and X2 plus twice the
distance from the centerline axis X1 or X2 to the tip of the
respective lobe. In some embodiments, width W is the same as or
more than the combined rotor diameter.
[0040] In another aspect of the expander geometry, the outlet port
26 includes an outlet angle 26-1, as can be seen schematically at
FIG. 6, and in the embodiment shown at FIGS. 4-5. In one
embodiment, the outlet angle 26-1 is defined as the general or
average angle of an inner surface 26a of the outlet port 26, for
example as shown at FIG. 8. In one embodiment, the outlet angle
26-1 is defined as the angle of the general centerline of the
outlet port 26, for example as shown at FIG. 6. In one embodiment,
the outlet angle 26-1 is defined as the general resulting direction
of the working fluid 12-2 leaving the rotors 30, 32 due to contact
with the inner surface 26a. As shown, the outlet angle 26-1 is
neither perpendicular nor parallel to the rotational axes X1, X2 of
the rotors 30, 32. Accordingly, the inner surface 26a of the outlet
port 26 receives the leaving working fluid 12-2 from the rotors 30,
32 at an oblique angle which can reduce backpressure at the outlet
port 26. In one embodiment, the inlet angle 24-1 and the outlet
angle 26-1 are generally equal or parallel, as shown in FIG. 6. In
one embodiment, the inlet angle 24-1 and the outlet angle 26-1 are
oblique with respect to each other. It is to be understood that the
inlet angle 24-1 may be generally perpendicular to axes X1, X2,
although an efficiency loss may be anticipated for certain rotor
configurations. It is further noted that the outlet angle 26-1 may
be perpendicular to the axes X1, X2. As configured, the orientation
and size of the outlet port 26 are established such that the
leaving working fluid 12-2 can evacuate each rotor cavity 28 as
easily and rapidly as possible so that backpressure is reduced as
much as possible. The output power of the shaft 38 is maximized to
the extent that backpressure caused by the outlet can be minimized
such that the working fluid can be rapidly discharged into the
lower pressure working fluid at the condenser.
[0041] The efficiency of the device 20 can be optimized by
coordinating the geometry of the inlet angle 24-1 and the geometry
of the rotors 30, 32. For example, the helix angle HA of the rotors
30, 32 and the inlet angle 24-1 can be configured together in a
complementary fashion. Because the inlet port 24 introduces the
working fluid 12-1 to both the leading and trailing faces of each
rotor 30, 32, the working fluid 12-1 performs both positive and
negative work on the device 20.
[0042] To illustrate, FIG. 7 shows that lobes 30-1, 30-4, 32-1, and
32-2 are each exposed to the working fluid 12-1 through the inlet
port opening 24b. Each of the lobes has a leading surface and a
trailing surface, both of which are exposed to the working fluid at
various points of rotation of the associated rotor. The leading
surface is the side of the lobe that is forward most as the rotor
is rotating in a direction R1, R2 while the trailing surface is the
side of the lobe opposite the leading surface. For example, rotor
30 rotates in direction R1 thereby resulting in side 30-1a as being
the leading surface of lobe 30-1 and side 30-1b being the trailing
surface. As rotor 32 rotates in a direction R2 which is opposite
direction R1, the leading and trailing surfaces are mirrored such
that side 32-2a is the leading surface of lobe 32-2 while side
32-2b is the trailing surface.
[0043] In generalized terms, the working fluid 12-1 impinges on the
trailing surfaces of the lobes as they pass through the inlet port
opening 24b and positive work is performed on each rotor 30, 32. By
use of the term positive work, it is meant that the working fluid
12-1 causes the rotors to rotate in the desired direction:
direction R1 for rotor 30 and direction R2 for rotor 32. As shown,
working fluid 12-1 will operate to impart positive work on the
trailing surface 32-2b of rotor 32-2, for example on surface
portion 47. The working fluid 12-1 is also imparting positive work
on the trailing surface 30-4b of rotor 30-1, for example of surface
portion 46. However, the working fluid 12-1 also impinges on the
leading surfaces of the lobes, for example surfaces 30-1 and 32-1,
as they pass through the inlet port opening 24b thereby causing
negative work to be performed on each rotor 30, 32. By use of the
term negative work, it is meant that the working fluid 12-1 causes
the rotors to rotate opposite to the desired direction, R1, R2.
[0044] Accordingly, it is desirable to shape and orient the rotors
30, 32 and to shape and orient the inlet port 24 such that as much
of the working fluid 12-1 as possible impinges on the trailing
surfaces of the lobes with as little of the working fluid 12-1
impinging on the leading lobe surfaces, such that the highest net
positive work can be performed by the device 20.
[0045] One advantageous configuration for optimizing the efficiency
and net positive work of the device 20 is a rotor lobe helix angle
HA of about 35 degrees and an inlet angle 24-1 of about 30 degrees.
Such a configuration operates to maximize the impingement area of
the trailing surfaces on the lobes while minimizing the impingement
area of the leading surfaces of the lobes. In one embodiment, the
helix angle is between about 25 degrees and about 40 degrees. In
one embodiment, the inlet angle 24-1 is set to be within (plus or
minus) 15 degrees of the helix angle HA. In one embodiment, the
helix angle is between about 25 degrees and about 40 degrees. In
one embodiment, the inlet angle 24-1 is set to be within (plus or
minus) 15 degrees of the helix angle HA. In one embodiment, the
inlet angle is within (plus or minus) 10 degrees of the helix
angle. In one embodiment, the inlet angle 24-1 is set to be within
(plus or minus) 5 degrees of the helix angle HA. In one embodiment,
the inlet angle 24-1 is set to be within (plus or minus) 15% of the
helix angle HA while in one embodiment, the inlet angle 24-1 is
within 10% of the helix angle. Other inlet angle and helix angle
values are possible without departing from the concepts presented
herein. However, it has been found that where the values for the
inlet angle and the helix angle are not sufficiently close, a
significant drop in efficiency (e.g. 10-15% drop) can occur.
Power Conversion Unit--Compression Device
[0046] As related previously, compression device 50 can have a
similar construction to that described in U.S. Pat. No. 7,488,164,
and has many overlapping features with the above described energy
recovery device 20. Accordingly, the description of the energy
recovery device 20 is hereby incorporated herein by reference in
its entirety for the compression device 50.
[0047] Referring to FIGS. 4, 5, and 11, schematics of three
embodiments of an integrated power conversion unit 15, 115 usable
with the above described systems are shown. In one aspect, the
power conversion unit 15 includes a compression device 50 having a
housing 52. As shown, the housing 52 includes an inlet port 54
configured to admit relatively low-pressure ambient air 54-1. The
housing 52 also includes an outlet port 56 configured to discharge
relatively high-pressure air 56-1 to the power plant 16. It is
noted that the locations of the inlet port 54 and the outlet port
56 may be provided either radially or axially, for example, an
axial inlet and a radial outlet.
[0048] The housing 52 of the compression device 50 also includes a
rotor cavity 58. As shown, disposed inside the rotor cavity 58 are
first and second twisted meshed rotors 60 and 62, respectively. The
rotors 60 and 62 are mounted for synchronous rotation in the rotor
cavity 58 and configured to compress relatively low-pressure
ambient air 54-1 into relatively high-pressure air 56-1.
Accordingly, the first and second meshed rotors 60 and 62 are
configured to generate a stream of relatively high-pressure air
56-1 that includes oxygen for subsequent delivery to the power
plant 16, which then generates power by using the supply of
compressed oxygen.
[0049] As shown, each rotor 60, 62 has a plurality of lobes 60-1,
62-1, respectively. In one embodiment, each rotor 60, 62 has three
lobes 60-1, 62-1 while in another embodiment, each rotor 60, 62 has
four lobes 60-1, 62-1. Accordingly, when one lobe of the rotor 60,
such as the lobe 60-1 is leading with respect to the inlet port 54,
a lobe of the rotor 60, such as the lobe 60-2, is trailing with
respect to the inlet port 64, and, therefore with respect to a
stream of the relatively low-pressure ambient air 54-1.
[0050] In one embodiment, the twist of each of the first and second
rotors 60 and 62 is constant along their substantially matching
length. The first and second rotors 60 and 62 are fixed to
respective rotor shafts, the first rotor being fixed to an input
shaft 68 and the second rotor being fixed to a shaft 69. Each of
the rotor shafts 68, 69 is mounted for rotation on a set of
bearings (not shown). The shaft 68 can be rotated by the power
plant 16 in order generate the stream of relatively high-pressure
air 56-1. Although the input shaft 68 is shown as being operatively
connected to the first rotor 60, in the alternative the shaft 69
may be operatively connected to the second rotor 62. The first and
second rotors 60 and 62 are interleaved and continuously meshed for
unitary rotation with each other.
[0051] With reference to FIGS. 4 and 11, the compressor 50 also
includes meshed timing gears 72 and 74, wherein the timing gear 72
is fixed for rotation with the rotor 60, while the timing gear 74
is fixed for rotation with the rotor 62. The timing gears 72, 74
are configured to maintain specified relative position between the
rotors 60, 62 and prevent contact between the rotors during
operation of the compressor 50.
[0052] It is noted that the energy recovery device 20 and the
compression device 50 could have rotors and housing of similar
construction, although some efficiency would likely be lost without
utilizing optimized rotors and inlets.
Power Conversion Unit--Power Transmission Link
[0053] The power conversion unit 15 can include a power
transmission link 80 between the energy recovery device 20 and the
compression device 50 such that waste heat from the power plant 16
can be converted into rotational energy by the energy recovery
device 20 that is then used to drive the compression device 50.
Accordingly, the link 80 can be configured to substantially match
the rotational speed of the device 50 with the rotational speed of
the power plant 16, wherein the speed of the power plant is
determined by the amount of oxygen used by the power plant to
generate the requisite power. It is noted that FIGS. 4 and 5 show
an integrated power conversion unit 15 in which the energy recovery
device 20, the compression device 50, and the link 80 are in a
common housing.
[0054] With reference to FIGS. 4 and 11, the link 80 is provided at
the end opposite timing gears 72, 74 of the compression device 50
and at the end opposite timing gears 42, 44 of the recovery device
20. As shown, shaft 38 of the recovery device 20 is configured as
an output shaft and shaft 69 of compression device 50 is configured
as an input shaft. Torque can be transferred between shafts 38 and
69 by mechanically coupling the shafts together, for example
through the use of a gear set having gears 81, 83 connected to
shafts 38, 69, respectively. The gear set may be configured as a
simple gear-train configured to define a particular speed ratio
between the compression device 50 and the recovery device 20. Also,
such a direct mechanical drive or simple gear-train may be used as
the link 80 in the situation when the power plant 16 is a fuel
cell. Other means for mechanically coupling the shafts are also
possible, for example, shaft 38 or 40 could be aligned and coupled
or welded directly to shafts 68 or 69, respectively. Also, shafts
38 and 68 can be provided as a single common shaft while shafts 40
and 69 can also be provided as a single common shaft.
[0055] It is noted that link 80 can be configured to replace the
timing gears 42, 44, 72, 74 by extending the shaft 40 to gear 83
and extending the shaft 68 to gear 81. In such a configuration,
both power transmission and rotor timing would be accomplished
through the same gear set, such that a single pair of timing gears
constitutes the set of timing gears of the system 14, and be
sufficient to suitably synchronize the rotation of the first and
second rotors 30, 32 of the device 20 to the third and fourth
rotors 60, 62 of the device 50.
[0056] With reference to FIG. 5, the recovery device 20 and the
compression device 50 are oriented such that the timing gears 72,
74 are adjacent to timing gears 42, 44. In this embodiment, the
recovery device 20 and compression device 50 are mechanically
coupled to each other through a variable speed drive 85, which is
shown as a compound planetary gear set structure having a common or
shared carrier member. Such a compound planetary gear set 85 may
provide a variable gear ratio configured to substantially match the
speeds of the power plant 16 and the device 20 depending on the
operating conditions experienced by the power plant 16.
[0057] With reference to FIGS. 5 and 5a, the shaft 68 can be
coupled to sun gear 85a of the planetary gear set 85, while shaft
38 can be coupled to a carrier 87 that is connected to a set of
planet gears 85b that are rotationally engaged with the sun gear
85a. A ring gear 85c is also provided that is shown as being
rotationally engaged with the planet gears 85b. When the position
of the ring gear 85c is fixed, all power from the shaft 38 is
transmitted to the shaft 68 at a first gear ratio defined by the
sun gear 85a and the planetary gears 85b. Where the ring gear 85c
is allowed to rotate, power can then be transmitted from shaft 38
to both shaft 68 and to the ring gear 85c. Such a configuration
allows for the desired rotational speed of the compression system
50 to be obtained while sending any excess power generated by the
recovery device 20 to the ring gear 85c.
[0058] In one embodiment, a generator or pump 82 may be placed in
operative connection with the ring gear 85c via a gear 89 that
interfaces with teeth 85d on the ring gear 85c. Other types of
drive systems are also possible, such as a belt and pulley. The
generator 82 can then be configured to vary and select on demand
the speed of the device 20 in order to substantially match the
rotating speeds of the power plant 16 and the device 50. Also, the
generator 82 may be operated as a brake to vary the speed of the
device 20, such that the device 20 may be permitted to freewheel
when the generator provides zero braking force. Furthermore, when
the device 20 is permitted to freewheel because zero braking is
being provided by the generator 82, parasitic drag from the device
on the compression system 50 may be reduced, i.e., minimized, to
increase operating efficiency of the entire system 14. When the
ring gear is allowed to freewheel then zero torque is transferred
similar to an open clutch condition. This would reduce losses
during idle condition when available exhaust energy is too low to
provide positive energy input back to the power plan 16.
[0059] With reference to FIGS. 4-6 and 11, the systems may also
include a drive system 90 to allow the power plant 16 to drive the
compression system 50 in the event that sufficient power is not
available from the energy recovery device 20. In one embodiment,
the drive system 90 includes an electric drive unit 91 that can
drive the compression device 50 independently of engine operation.
In another embodiment, and as shown at FIG. 11, the drive system 90
can include a drive unit 91 in the form of a pulley that is in
power communication with the power plant 16 via a power output
location (e.g. pulley 16b and belt 16c), as is found on typical
roots-type blowers. Gear reducing systems are also possible. The
embodiment of FIG. 11 is also shown as being provided with a clutch
93 such that the drive system 90 can be decoupled from the
compression device 50 when desirable, such as when it is desired to
fully drive the compression device 50 with only the expansion
device 20. As an alternative to clutch 93, a one-way bearing set at
the pulley may also be provided. Where so desired, link 80 can also
include a clutch such that the recovery device 20 is not
undesirably rotated by the drive system 90.
System Control and Operation
[0060] Any of the systems shown in FIGS. 1-3 and any of the
configurations shown in FIGS. 4, 5, and 11 may be operated through
a control system. Such a system is presented at FIG. 1 which shows
an electronic controller. The electronic controller 500 is
schematically shown as including a processor 500A and a
non-transient storage medium or memory 500B, such as RAM, a flash
drive or a hard drive. Memory 500B is for storing executable code,
the operating parameters, and the input from the operator user
interface 500D, while processor 500A is for executing the code. The
electronic controller is also shown as including a
transmitting/receiving port 500C, such as a vehicle CAN bus. A user
interface 500D may also be provided to activate and deactivate the
system, allow a user to manipulate certain settings or inputs to
the controller 500, and to view information about the system
operation.
[0061] The electronic controller 500 typically includes at least
some form of memory 500B. Examples of memory 500B include computer
readable media. Computer readable media includes any available
media that can be accessed by the processor 500A. By way of
example, computer readable media includes computer readable storage
media and computer readable communication media.
[0062] Computer readable storage media includes volatile and
nonvolatile, removable and non-removable media implemented in any
device configured to store information such as computer readable
instructions, data structures, program modules, or other data.
Computer readable storage media includes, but is not limited to,
random access memory, read only memory, electrically erasable
programmable read only memory, flash memory or other memory
technology, compact disc read only memory, digital versatile disks
or other optical storage, magnetic cassettes, magnetic tape,
magnetic disk storage or other magnetic storage devices, or any
other medium that can be used to store the desired information and
that can be accessed by the processor 500A.
[0063] Computer readable communication media typically embodies
computer readable instructions, data structures, program modules or
other data in a modulated data signal such as a carrier wave or
other transport mechanism and includes any information delivery
media. The term "modulated data signal" refers to a signal that has
one or more of its characteristics set or changed in such a manner
as to encode information in the signal. By way of example, computer
readable communication media includes wired media such as a wired
network or direct-wired connection, and wireless media such as
acoustic, radio frequency, infrared, and other wireless media.
Combinations of any of the above are also included within the scope
of computer readable media.
[0064] Electronic controller 500 is also shown as having a number
of inputs/outputs that may be used for implementing desired
operational modes of the power conversion unit 15. For example,
electronic controller 500 provides outputs for commanding an
expander bypass valve 202, a compressor bypass valve 204, and for
controlling the drive system 90 (e.g. activating and deactivating
clutch 93 and/or drive motor 91). Likewise, electronic controller
500 receives inputs for the control of the power conversion unit
15, for example an input from pressure sensor 206 upstream of the
expansion device 20, an input from pressure sensor 208 downstream
of the expansion device, and various other inputs via the vehicle
CAN bus. It is also noted that the above described components of
controller 500 may simply be implemented as part of the primary
vehicle operating system controller and is not necessarily a
separate controller.
[0065] In operation, the expander bypass valve 202 can be
controlled to maintain a pressure differential set point across the
expansion device 20, as measured by the difference between the
pressure signals received from sensors 206 and 208. The pressure
differential across the expansion device 20 directly corresponds to
the torque produced by the expansion device 20. Additionally, the
operation of the expander bypass valve 202 allows for the
backpressure on the power plant exhaust to be controlled such that
excessive backpressure is not caused by the expansion device 20
which could result in significant efficiency reductions for the
power plant 16. Similarly, the compressor bypass valve 204 can be
operated to allow for excess compressed intake air to be diverted
back to the intake of the compression device 50 in order to avoid
over pressurization of the intake air manifold 13. When the
compressor bypass valve 204 is fully open, the ability of the
compression device 50 to develop a differential pressure across the
compression device 50 is greatly diminished, which also has the
effect of lowering the brake horsepower of the compression device
50.
[0066] As previously stated, the clutch 93 can be either engaged or
disengaged. When the clutch 93 is disengaged, the compression
device 50 cannot be driven by the power plant 16. Therefore, the
compression device 50 is driven solely by the expansion device 20
when the clutch 93 is disengaged. This mode of operation may be
suitable where the power plant is running at a constant load (e.g.
vehicle is operating at cruising speed on a highway) and the
available waste heat from the power plant 16 is sufficient to drive
the compression device 50 solely through the expansion device
20.
[0067] When the clutch 93 is engaged, the compression device 50 can
be driven by the power plant 16. When the compression device 50 is
being driven by the power plant 16, the bypass valve 202 for the
expansion device 20 can be opened to reduce the parasitic losses
caused by the expansion device 20. Alternatively, and as mentioned
previously, a clutch can be provided between the expansion device
20 and the compression device 50 to decouple the devices 20, 50. It
is also possible for the expansion device 20 and the power plant 16
to both provide power simultaneously to the compression device 50.
Also, when the expansion device 20 is able to generate more power
than is required by the compression device or when compression is
not needed by the compression device 50, the clutch 93 can remain
engaged and the excess power developed by the expansion device 20
can be transmitted through the compression device 50 and back to
the power plant 16 via the drive system 90 (e.g. pulleys 91, 16b
and the connected belt 16c). The bypass valve 204 can be operated
to smooth the transition between driving the compression device 50
via the drive system 90 and driving the compression device 50 via
the expansion device 20. The above described control and
configuration increases the power band range through which the
compression device 50 can be operated to boost engine power,
thereby increasing engine performance and efficiency.
[0068] The detailed description and the drawings or figures are
supportive and descriptive of the invention, but the scope of the
invention is defined solely by the claims. While some of the best
modes and other embodiments for carrying out the claimed invention
have been described in detail, various alternative designs and
embodiments exist for practicing the invention defined in the
appended claims.
* * * * *