U.S. patent application number 11/863677 was filed with the patent office on 2008-04-03 for microchannel heat exchanger.
Invention is credited to Peter James Breiding, Cosimo Caronna.
Application Number | 20080078198 11/863677 |
Document ID | / |
Family ID | 38982901 |
Filed Date | 2008-04-03 |
United States Patent
Application |
20080078198 |
Kind Code |
A1 |
Breiding; Peter James ; et
al. |
April 3, 2008 |
MICROCHANNEL HEAT EXCHANGER
Abstract
A microchannel heat exchanger is provided that is configured to
drain condensate out of the microchannel heat exchanger. The
microchannel heat exchanger has tube sections that are positioned
at an angle with respect to a horizontal plane when the
microchannel heat exchanger has a vertical orientation. The fins
between the tube sections can be positioned perpendicular to the
angled tube sections or can be positioned perpendicular to the
horizontal plane.
Inventors: |
Breiding; Peter James;
(Wichita, KS) ; Caronna; Cosimo; (Wichita,
KS) |
Correspondence
Address: |
MCNEES WALLACE & NURICK LLC
100 PINE ST., P.O. BOX 1166
HARRISBURG
PA
17108-1166
US
|
Family ID: |
38982901 |
Appl. No.: |
11/863677 |
Filed: |
September 28, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60827387 |
Sep 28, 2006 |
|
|
|
Current U.S.
Class: |
62/324.5 ;
165/170 |
Current CPC
Class: |
F28D 1/05383 20130101;
F28F 9/0131 20130101; F28B 9/08 20130101; F25B 2500/01 20130101;
F28F 17/005 20130101; F28F 2260/02 20130101; F25B 39/00
20130101 |
Class at
Publication: |
62/324.5 ;
165/170 |
International
Class: |
F25B 13/00 20060101
F25B013/00; F28F 3/14 20060101 F28F003/14 |
Claims
1. A microchannel heat exchanger comprising: first and second
support members, the first and second support members being
disposed substantially parallel to each other; a plurality of tube
sections disposed between the first and second support members,
each tube section of the plurality of tube sections having a
plurality of tubes to circulate a fluid; a plurality of fins
disposed between the plurality of tube sections; and wherein the
plurality of tube sections are positioned at a predetermined angle
with respect to the first and second support members.
2. The microchannel heat exchanger of claim 1 wherein the
predetermined angle is between about 3 degrees and about 45
degrees.
3. The microchannel heat exchanger of claim 2 wherein the
predetermined angle is about 15 degrees.
4. The microchannel heat exchanger of claim 1 wherein the plurality
of fins are oriented substantially perpendicular to the plurality
of tube sections.
5. The microchannel heat exchanger of claim 1 wherein the plurality
of fins are oriented substantially perpendicular to the first and
second support members.
6. The microchannel heat exchanger of claim 1 wherein the position
of the plurality of tube sections at the predetermined angle
permits drainage of condensate from the microchannel heat
exchanger.
7. The microchannel heat exchanger of claim 1 wherein the first and
second support members, the plurality of tube sections and the
plurality of fins are oriented substantially vertically with
respect to each other.
8. An outdoor unit for an air conditioning or heat pump system
comprising: a compressor to compress a refrigerant for the system;
a fan configured and disposed to circulate air through the outdoor
unit; and a microchannel heat exchanger, the microchannel heat
exchanger comprising: at least one support member extending
substantially horizontally; a plurality of tube sections disposed
adjacent to the at least one support member, each tube section of
the plurality of tube sections having a plurality of tubes to
circulate a fluid; a plurality of fins disposed between the
plurality of tube sections; and wherein the plurality of tube
sections are positioned at a predetermined angle with respect to
the at least one support member.
9. The outdoor unit of claim 8 wherein the predetermined angle is
between about 3 degrees and about 45 degrees.
10. The outdoor unit of claim 9 wherein the predetermined angle is
about 15 degrees.
11. The outdoor unit of claim 8 wherein the plurality of fins are
oriented substantially perpendicular to the plurality of tube
sections.
12. The outdoor unit of claim 8 wherein the plurality of fins are
oriented substantially perpendicular to the at least one support
member.
13. The outdoor unit of claim 8 wherein the position of the
plurality of tube sections at the predetermined angle permits
drainage of condensate from the microchannel heat exchanger.
14. The outdoor unit of claim 8 wherein the at lest one support
member, the plurality of tube sections and the plurality of fins
are oriented substantially vertically with respect to each
other.
15. A microchannel heat exchanger comprising: a plurality of tubes
extending substantially horizontally and disposed substantially
parallel to one another, each tube of the plurality of tubes having
a plurality of channels to circulate a fluid; a plurality of fins
disposed between the plurality of tubes; at least one header
configured and disposed to distribute fluid to the plurality of
tubes; the plurality of tubes are positioned at a predetermined
angle with respect to a horizontal plane; and wherein the plurality
of tubes, the plurality of fins and the at least one header are
oriented substantially vertically with respect to each other.
16. The microchannel heat exchanger of claim 15 wherein the
plurality of fins are oriented substantially perpendicular to the
plurality of tubes.
17. The microchannel heat exchanger of claim 15 wherein the
plurality of fins are oriented substantially perpendicular to the
horizontal plane.
18. The microchannel heat exchanger of claim 15 wherein the
position of the plurality of tubes at the predetermined angle
permits drainage of condensate from the microchannel heat
exchanger.
19. The microchannel heat exchanger of claim 15 wherein the
predetermined angle is between about 3 degrees and about 45
degrees.
20. The microchannel heat exchanger of claim 19 wherein the
predetermined angle is about 15 degrees.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/827,387 filed on Sep. 28, 2006, which
Application is hereby incorporated by reference.
BACKGROUND
[0002] The application generally relates to microchannel heat
exchangers. The application relates more specifically to the
drainage of condensate from microchannel heat exchangers.
[0003] In a typical microchannel heat exchanger or coil slab, a
series of tube sections are connected (physically and thermally) by
fins that are configured to permit airflow through the heat
exchanger in order to provide for heat transfer between the airflow
and a circulating fluid, e.g., water or refrigerant. The tube
sections of the heat exchanger are oriented to extend horizontally
(but can be oriented vertically) and each tube section has several
tubes or channels that are used to circulate the fluid. The outside
of the tube section is a continuous surface typically having a
rectangular shape. The continuous surface of the tube sections
provides a place for moisture to be trapped on the top surface of
the tube sections between the connecting fins.
[0004] The collection or trapping of moisture on the top surface of
the horizontally oriented tube sections severely limits the use of
microchannel heat exchangers in heat pump applications. In a heat
pump application, the outdoor coil serves as the evaporator when
the heat pump is operating in a heating mode. When operating as an
evaporator, the outdoor coil is removing heat and moisture from the
outdoor air. The removed moisture may then collect on the top
surface of the tube sections and decrease system performance by
reducing the airflow through the heat exchanger as a result of a
greater pressure drop. This moisture may also freeze under certain
conditions, further reducing the airflow through the heat exchanger
and thereby lowering the efficiency and capacity of the system.
[0005] Some techniques to attempt to reduce the amount of moisture
collecting on the top surface of the tube sections include the
application of hydrophilic coatings to the surfaces of the heat
exchanger and the slanting of the entire heat exchanger. The use of
hydrophilic coatings has many drawbacks including increased costs
(for both the coating and its application) and greater
susceptibility to damage and performance degradation. Furthermore,
the slanting of the entire heat exchanger has not been shown to
increase condensate drainage and results in significant
manufacturing issues and costs from having to interconnect
individual coil slabs.
[0006] Intended advantages of the disclosed systems and/or methods
satisfy one or more of these needs or provides other advantageous
features. Other features and advantages will be made apparent from
the present specification. The teachings disclosed extend to those
embodiments that fall within the scope of the claims, regardless of
whether they accomplish one or more of the aforementioned
needs.
SUMMARY
[0007] One embodiment relates to a microchannel heat exchanger
having first and second support members, a plurality of tube
sections disposed between the first and second support members, and
a plurality of fins disposed between the plurality of tube
sections. The first and second support members are disposed
substantially parallel to each other. Each tube section of the
plurality of tube sections has a plurality of tubes to circulate a
fluid. The plurality of tube sections are positioned at a
predetermined angle with respect to the first and second support
members.
[0008] Another embodiment relates to an outdoor unit for an air
conditioning or heat pump system having a compressor to compress a
refrigerant for the system, a fan configured and disposed to
circulate air through the outdoor unit, and a microchannel heat
exchanger. The microchannel heat exchanger includes at least one
support member, a plurality of tube sections disposed adjacent to
the at least one support member, and a plurality of fins disposed
between the plurality of tube sections. Each tube section of the
plurality of tube sections has a plurality of tubes to circulate a
fluid. The plurality of tube sections are positioned at a
predetermined angle with respect to the at least one support
member.
[0009] A further embodiment relates to a microchannel heat
exchanger having a plurality of tubes extending substantially
horizontally and disposed substantially parallel to one another, a
plurality of fins disposed between the plurality of tubes, and at
least one header configured and disposed to distribute fluid to the
plurality of tubes. Each tube of the plurality of tubes has a
plurality of channels to circulate a fluid. The plurality of tubes
are positioned at a predetermined angle with respect to a
horizontal plane. The plurality of tubes, the plurality of fins and
the at least one header are oriented substantially vertically with
respect to each other.
[0010] Certain advantages of the embodiments described herein are
improved condensate drainage from the microchannel heat exchanger
while maintaining a single slab design, and potentially increased
airflow through the microchannel heat exchanger.
[0011] Alternative exemplary embodiments relate to other features
and combinations of features as may be generally recited in the
claims.
BRIEF DESCRIPTION OF THE FIGURES
[0012] FIG. 1A is a schematic illustration of a refrigeration
system.
[0013] FIG. 1B is a schematic illustration of a heat pump
system.
[0014] FIG. 2 is partial cross-sectional view of an outdoor unit
used in a heat pump system.
[0015] FIG. 3 is a schematic end view of one embodiment of a
drainage configuration for a microchannel heat exchanger.
[0016] FIG. 4 is a partial side view of the embodiment of the
microchannel heat exchanger of FIG. 3.
[0017] FIG. 5 is a schematic end view of another embodiment of a
drainage configuration for a microchannel heat exchanger.
[0018] FIG. 6 is an isometric view of the embodiment of the
microchannel heat exchanger of FIG. 5.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
[0019] In FIGS. 1A and 1B, a heating, ventilation, air conditioning
and refrigeration (HVAC&R) system 100 includes a compressor
102, a condenser 104, an evaporator 106, and a control panel 108
(FIG. 1A) or a compressor 102, a reversing valve 150, an indoor
unit 154, an outdoor unit 152 and a control panel 108 (FIG. 1B).
Circulating through system 100 is a refrigerant. Some examples of
refrigerants that may be used in system 100 are hydrofluorocarbon
(HFC) based refrigerants, e.g., R-410A, R-407, R-134a, carbon
dioxide, CO.sub.2, (R-744), ammonia, NH.sub.3, (R-717), and any
other suitable type of refrigerant. The HVAC&R system 100 may
include many other features that are not shown in FIGS. 1A and
1B.
[0020] System 100 can be operated as an air conditioning only
system, where evaporator 106 is located indoors, i.e., as indoor
unit 154, to provide cooling to the indoor air and condenser 104 is
preferably located outdoors, i.e., as outdoor unit 152, to
discharge heat to the outdoor air. System 100 can also be operated
as a heat pump system with the inclusion of reversing valve 150 to
control and direct the flow of refrigerant from compressor 102.
When the heat pump is operated in an air conditioning mode,
reversing valve 150 is controlled for refrigerant flow as described
above for an air conditioning system. However, when the heat pump
is operated in a heating mode, the flow of the refrigerant is in
the opposite direction from the air conditioning mode and condenser
104 is preferably located indoors, i.e., as indoor unit 154, to
provide heating of the indoor air and evaporator 106 is preferably
located outdoors, i.e., as outdoor unit 152, to absorb heat from
the outdoor air.
[0021] Compressor 102 compresses a refrigerant vapor and delivers
the vapor to condenser 104 through a discharge line (and reversing
valve 150 if operated as a heat pump). Compressor 102 can be a
screw compressor, reciprocating compressor, centrifugal compressor,
rotary compressor, swing link compressor, scroll compressor,
turbine compressor, or any other suitable compressor. The
refrigerant vapor delivered by compressor 102 to condenser 104
enters into a heat exchange relationship with a fluid, e.g., air,
and undergoes a phase change to a refrigerant liquid as a result of
the heat exchange relationship with the fluid. The condensed liquid
refrigerant from condenser 104 flows through an expansion device
110 to evaporator 106.
[0022] The condensed liquid refrigerant delivered to evaporator 106
enters into a heat exchange relationship with a fluid, e.g., air,
and undergoes a phase change to a refrigerant vapor as a result of
the heat exchange relationship with the fluid. The vapor
refrigerant in evaporator 106 exits evaporator 106 and returns to
compressor 102 by a suction line to complete the cycle (and
reversing valve 150 if operated as a heat pump).
[0023] Compressor 102 of system 100, whether operated as a heat
pump or as an air conditioner, is driven by a motor or drive
mechanism 120. Motor 120 can be powered by a variable speed drive
(VSD) or can be powered directly from an AC or DC power source. The
VSD, if used, receives AC power having a particular fixed line
voltage and fixed line frequency from the AC power source and
provides power to motor 120 having a variable voltage and
frequency. Motor 120 used in system 100 can be any type of electric
motor that can be powered by a VSD or directly from an AC or DC
power source. For example, motor 120 can be a switched reluctance
(SR) motor, an induction motor, an electronically commutated
permanent magnet motor (ECM), or any other suitable motor type.
[0024] Control panel 108 can include an analog to digital (A/D)
converter, a microprocessor, a non-volatile memory, and an
interface board to control operation of the HVAC&R system 100.
Control panel 108 can execute a control algorithm(s) to control
operation of system 100. While the control algorithm can be
embodied in a computer program(s) and executed by the
microprocessor, it is to be understood that the control algorithm
may be implemented and executed using digital and/or analog
hardware by those skilled in the art. If hardware is used to
execute the control algorithm, the corresponding configuration of
control panel 108 can be changed to incorporate the necessary
components and to remove any components that may no longer be
required.
[0025] In one embodiment, condenser 104 and/or evaporator 106 can
include one or more microchannel heat exchangers or coil slabs. The
microchannel heat exchanger circulates refrigerant through two or
more tube sections, each of which has two more tubes, passageways
or microchannels for the flow of refrigerant (see e.g., FIGS. 3 and
5). The tube section can have a cross-sectional shape in the form
or a rectangle, parallelogram, trapezoid, ellipse, oval or other
similar geometric shape. The tubes in the tube section can have a
cross-sectional shape in the form of a rectangle, square, circle,
oval, ellipse, triangle, trapezoid, parallelogram or other suitable
geometric shape. In one embodiment, the tubes in the tube section
can have a size, e.g., width or diameter, of between about a half
(0.5) millimeter (mm) to about a three (3) millimeters (mm). In
another embodiment, the tubes in the tube section can have a size,
e.g., width or diameter, of about one (1) millimeter (mm).
[0026] Connected between the tube sections are two or more fins or
fin sections. In one embodiment, the fins can be arranged to extend
substantially perpendicular to the flow of refrigerant in the tube
sections. However, in another embodiment, the fins can be arranged
to extend substantially parallel to the flow of refrigerant in the
tube sections. The fins can be louvered fins, corrugated fins or
any other suitable type of fin. Finally, any suitable distribution
system or header can be used to distribute the refrigerant in the
tubes.
[0027] In FIG. 2, outdoor unit 152 can include a heat exchanger or
coil slab 202 that provides for the exchange of heat between the
refrigerant circulating in heat exchanger 202 and the outdoor air.
To assist in the transfer of heat in heat exchanger 202, a fan 204
can be used to circulate the outdoor air through heat exchanger
202. The fan 204 can be configured to circulate the outdoor air by
either pushing or pulling the outdoor air through heat exchanger
202.
[0028] FIGS. 3-6 show embodiments of heat exchanger 202 as a
microchannel heat exchanger or coil slab that is oriented
substantially vertically. The substantially vertical orientation of
microchannel heat exchanger 202 permits microchannel heat exchanger
202 to be manufactured as a single heat exchanger or coil slab.
[0029] In FIGS. 3 and 4, an exemplary embodiment of microchannel
heat exchanger 202 includes support members 308 at the top and
bottom of microchannel heat exchanger 202. Support members 308 are
substantially parallel to one another and are arranged to provide
the substantial vertical orientation of microchannel heat exchanger
202. In addition, microchannel heat exchanger 202 includes two or
more tube sections 302 that extend substantially horizontally
between top and bottom support members 308. Tube sections 302 can
be connected to one or more distribution systems or headers for the
distribution of refrigerant in tube sections 302. Each tube section
302 has two or more tubes, passageways or microchannels 304 for the
flow or circulation of refrigerant through microchannel heat
exchanger 202. The tube section 302 can have a cross-sectional
shape in the form or a rectangle, parallelogram, trapezoid,
ellipse, oval or other similar geometric shape. The tubes 304 in
tube section 302 can have a cross-sectional shape in the form of a
rectangle, square, circle, oval, ellipse, triangle, trapezoid,
parallelogram or other suitable geometric shape. In one embodiment,
the tubes 304 in tube section 302 can have a size, e.g., width or
diameter, of between about a half (0.5) millimeter (mm) to about a
three (3) millimeters (mm). In another embodiment, the tubes 304 in
tube section 302 can have a size, e.g., width or diameter, of about
one (1) millimeter (mm).
[0030] Tube sections 302 in FIGS. 3 and 4 are positioned
substantially parallel to one another and at an angle (A) with
respect to support members 308. The positioning of tube sections
302 at the angle (A) facilitates the drainage of condensation from
microchannel heat exchanger 202 and can prevent the accumulation of
condensation on the top surfaces of tube sections 302. In one
embodiment, the angle (A) can be between about three (3) degrees
and about forty-five (45) degrees. In another embodiment, the angle
(A) can be about fifteen (15) degrees.
[0031] Connected between tube sections 302 are two or more fins or
fin sections 306. Fins 306 can be arranged to extend substantially
parallel to the flow of refrigerant in the tube sections 302. In
addition, fins 306 can be positioned to be substantially
perpendicular to the support members 308 when viewed in
cross-section as shown in FIG. 3. To be able to position fins 306
substantially perpendicular to support members 308, fins 306 have
to be manufactured to have a substantially parallelogram shaped
outline or cross-section. This substantially parallelogram shaped
outline or cross-section of fin 306, permits fin 306 to be in
contact with the entire width of both surrounding tube sections
302. The fins 306 can be louvered fins, corrugated fins or any
other suitable type of fine. Furthermore, with the positioning of
fins 306 substantially perpendicular to support members 308, any
corresponding vertical louvers located in fins 306 (as shown in
FIG. 3) would also be substantially perpendicular to support
members 308. Finally, as a result of tube sections 302 being angled
with respect to the support members 308, there is a space between
tube sections 302 and support members 308. This space can remain
open, can be used for additional support members, or can be used
for additional fins.
[0032] In FIGS. 5 and 6, another embodiment of microchannel heat
exchanger 202 includes support members 318 at the top and bottom of
microchannel heat exchanger 202. Support members 318 are
substantially parallel to one another and are arranged to provide
the substantial vertical orientation of microchannel heat exchanger
202. In addition, microchannel heat exchanger 202 includes two or
more tube sections 312 that extend substantially horizontally
between top and bottom support members 318. Tube sections 312 can
be connected to one or more distribution systems or headers for the
distribution of refrigerant therein (as shown in FIG. 6). Each tube
section 312 has two or more tubes, passageways or microchannels 314
for the flow or circulation of refrigerant through microchannel
heat exchanger 202. Tube section 312 can have a cross-sectional
shape in the form or a rectangle, parallelogram, trapezoid,
ellipse, oval or other similar geometric shape. The tubes 314 in
tube section 312 can have a cross-sectional shape in the form of a
rectangle, square, circle, oval, ellipse, triangle, trapezoid,
parallelogram or other suitable geometric shape. In one embodiment,
the tubes 314 in the tube section 312 can have a size, e.g., width
or diameter, of between about a half (0.5) millimeter (mm) to about
a three (3) millimeters (mm). In another embodiment, the tubes 314
in tube section 312 can have a size, e.g., width or diameter, of
about one (1) millimeter (mm).
[0033] Tube sections 312 in FIGS. 5 and 6 are positioned
substantially parallel to one another and at an angle (B) with
respect to support members 318. The positioning of tube sections
312 at the angle (B) facilitates the drainage of condensation from
microchannel heat exchanger 202 and can prevent the accumulation of
condensation on the top surfaces of tube sections 312. In one
embodiment, the angle (B) can be between about three (3) degrees
and about forty-five (45) degrees. In another embodiment, the angle
(B) can be about fifteen (15) degrees.
[0034] Connected between tube sections 312 are two or more fins or
fin sections 316. Fins 316 can be arranged to extend substantially
parallel to the flow of refrigerant in tube sections 312. In
addition, fins 316 can be positioned to be substantially
perpendicular to tube sections 312 when viewed in cross-section as
shown in FIG. 5. To obtain the substantially perpendicular
orientation of fins 316 with respect to the tube sections 312, fins
316 can be manufactured as is known in the art and then angled at
the same angle as the tube sections 312. The fins 316 can be
louvered fins, corrugated fins or any other suitable type of fin.
Furthermore, with the positioning of fins 316 substantially
perpendicular to tube sections 312, any corresponding vertical
louvers located in fins 316 (as shown in FIG. 5) would also be
substantially perpendicular to tube sections 312. Finally, as a
result of tube sections 312 being angled with respect to the
support members 318, there is a space between tube sections 312 and
support members 318. This space can remain open, can be used for
additional support members, or can be used for additional fins.
[0035] Tube sections 302, 312 in the embodiments of FIGS. 3-6 can
be angled such that the drainage of the condensation from
microchannel heat exchanger 202 is out of outdoor unit 152, i.e.,
away from compressor 102. However, tube sections 302, 312 in the
embodiments of FIGS. 3-6 can also be angled such that the drainage
of the condensation from microchannel heat exchanger 202 is into
outdoor unit 152, i.e., toward compressor 102. When draining the
condensate into the outdoor unit 152, an additional drainage system
may be needed to remove the condensate from the interior of the
outdoor unit 152.
[0036] In another embodiment, the fins of the microchannel heat
exchanger can be arranged to extend substantially perpendicular to
the tube sections. Each perpendicularly extending fin can have a
plurality of apertures arranged at the same angle as is desired for
the corresponding tube sections. Then, when the microchannel heat
exchanger is assembled, the tube sections are angled to permit
drainage of condensation from the microchannel heat exchanger.
[0037] In a further embodiment, the microchannel heat exchanger can
be made without either or both of the top and bottom support
members. The connection of the header(s) to the tube sections in
the microchannel heat exchanger may provide the necessary support
and rigidity for the microchannel heat exchanger to be able to
remove the support members.
[0038] While microchannel heat exchanger 202 has been described for
use in outdoor unit 152, it is to be understood that microchannel
heat exchanger 202 can also be used for indoor unit 154. By using
the same heat exchanger for both indoor unit 154 and the outdoor
unit 152, only one type of heat exchanger has to be provided and
indoor unit 154 can benefit from the advantages of the microchannel
heat exchanger 202.
[0039] It should be understood that the application is not limited
to the details or methodology set forth in the following
description or illustrated in the figures. It should also be
understood that the phraseology and terminology employed herein is
for the purpose of description only and should not be regarded as
limiting.
[0040] While the exemplary embodiments illustrated in the figures
and described herein are presently preferred, it should be
understood that these embodiments are offered by way of example
only. Accordingly, the present application is not limited to a
particular embodiment, but extends to various modifications that
nevertheless fall within the scope of the appended claims. The
order or sequence of any processes or method steps may be varied or
re-sequenced according to alternative embodiments.
[0041] It is important to note that the construction and
arrangement of the microchannel heat exchanger as shown in the
various exemplary embodiments is illustrative only. Although only a
few embodiments have been described in detail in this disclosure,
those skilled in the art who review this disclosure will readily
appreciate that many modifications are possible (e.g., variations
in sizes, dimensions, structures, shapes and proportions of the
various elements, values of parameters, mounting arrangements, use
of materials, colors, orientations, etc.) without materially
departing from the novel teachings and advantages of the subject
matter recited in the claims. For example, elements shown as
integrally formed may be constructed of multiple parts or elements,
the position of elements may be reversed or otherwise varied, and
the nature or number of discrete elements or positions may be
altered or varied. Accordingly, all such modifications are intended
to be included within the scope of the present application. The
order or sequence of any process or method steps may be varied or
re-sequenced according to alternative embodiments. In the claims,
any means-plus-function clause is intended to cover the structures
described herein as performing the recited function and not only
structural equivalents but also equivalent structures. Other
substitutions, modifications, changes and omissions may be made in
the design, operating conditions and arrangement of the exemplary
embodiments without departing from the scope of the present
application.
* * * * *