U.S. patent application number 11/729410 was filed with the patent office on 2008-10-02 for heat exchanger and method.
This patent application is currently assigned to Modine Manufacturing Company. Invention is credited to David W. Mast, Thomas J. Reiss, Christopher P. Schils.
Application Number | 20080236792 11/729410 |
Document ID | / |
Family ID | 39719609 |
Filed Date | 2008-10-02 |
United States Patent
Application |
20080236792 |
Kind Code |
A1 |
Mast; David W. ; et
al. |
October 2, 2008 |
Heat exchanger and method
Abstract
A heat exchanger and a method of manufacturing a heat exchanger
for transferring heat energy between first and second working
fluids. The heat exchanger can include a housing, a plurality of
tubes extending through the housing, and a baffle integrally formed
with the housing. The baffle can include one or more fingers that
can extend between at least two of the plurality of tubes. The
method can include forming a baffle integrally from a side of a
housing and positioning the baffle such that it extends into the
interior space defined by the housing.
Inventors: |
Mast; David W.; (Burlington,
WI) ; Reiss; Thomas J.; (West Allis, WI) ;
Schils; Christopher P.; (Joplin, MO) |
Correspondence
Address: |
MICHAEL BEST & FRIEDRICH LLP
100 E WISCONSIN AVENUE, Suite 3300
MILWAUKEE
WI
53202
US
|
Assignee: |
Modine Manufacturing
Company
Racine
WI
|
Family ID: |
39719609 |
Appl. No.: |
11/729410 |
Filed: |
March 28, 2007 |
Current U.S.
Class: |
165/157 ;
165/158 |
Current CPC
Class: |
F02M 26/32 20160201;
F28F 9/22 20130101; F28D 7/1684 20130101; B23P 15/26 20130101; F28F
9/00 20130101; F28F 2265/26 20130101 |
Class at
Publication: |
165/80.4 |
International
Class: |
F28F 7/02 20060101
F28F007/02 |
Claims
1. A heat exchanger for transferring heat energy between a first
working fluid and a second working fluid, the heat exchanger
comprising: a housing having a first end and a second end; a
plurality of tubes extending through the housing between the first
end and the second end and providing a flow path for the first
working fluid; and a baffle integrally formed with the housing for
directing the flow of the second working fluid through the
housing.
2. The heat exchanger of claim 1, wherein the baffle includes a
finger extending between two of the plurality of tubes.
3. The heat exchanger of claim 2, wherein the finger defines a
bypass aperture extending between a first side of the finger and a
second side of the finger.
4. The heat exchanger of claim 1, wherein the baffle is moveably
supported in the housing for movement relative to at least one of
the plurality of tubes.
5. The heat exchanger of claim 4, wherein the baffle is movable in
a direction substantially normal to a length of one of the
plurality of tubes.
6. The heat exchanger of claim 1, wherein the housing is formed
from a first housing portion and a second housing portion secured
to the first housing portion, and wherein the baffle extends into
an interior space defined between the first housing portion and the
second housing portion.
7. The heat exchanger of claim 6, wherein the baffle is a first
baffle and is integrally formed with the first housing portion, and
further comprising a second baffle extending into the interior
space from the second housing portion.
8. The heat exchanger of claim 7, wherein the second baffle is
integrally formed with the second housing portion.
9. The heat exchanger of claim 6, wherein the baffle is a first
baffle and is integrally formed with the first housing portion, and
further comprising a second baffle integrally formed with the first
housing portion and extending into the interior space.
10. The heat exchanger of claim 1, wherein the baffle is a first
baffle, wherein the first baffle is adjacent to the first end of
the housing, and wherein a second baffle is integrally formed with
the housing adjacent to the second end of the housing.
11. A method of manufacturing a heat exchanger for transferring
heat energy between a first working fluid and a second working
fluid, the method comprising the acts of: providing a housing
having a first side wall and a second side wall oriented at an
angle with respect to the first side wall, together the first and
second side walls at least partially defining an interior space;
forming a finger from the first side wall; positioning a plurality
of tubes in the interior space; and positioning the finger between
two of the plurality of tubes.
12. The method of claim 11, wherein forming the finger from the
first side wall includes forming a plurality of fingers, and
wherein positioning the finger between the two of the plurality of
tubes includes moving at least two of the plurality of fingers into
the interior space between the plurality of tubes.
13. The method of claim 11, further comprising providing a bypass
aperture in the finger such that the working fluid can flow through
the finger from an inlet end of the housing toward an outlet end of
the housing.
14. The method of claim 11, wherein positioning the finger between
the two of the plurality of tubes includes folding the finger into
the interior space between the two of the plurality of tubes.
15. The method of claim 11, wherein forming the finger from the
first side wall includes cutting the first side wall.
16. The method of claim 11, further comprising moving the finger
relative to the first side wall in a direction substantially normal
to a longitudinal axis of one of the plurality of tubes.
17. The method of claim 11, wherein forming the finger from the
first side wall includes molding the first finger.
18. A method of manufacturing a heat exchanger for transferring
heat energy between a first working fluid and a second working
fluid, the method comprising the acts of: providing a generally
planar housing plate; folding the plate to define a first side wall
and a second side wall oriented at an angle with respect to the
first side wall such that the first and second side walls together
at least partially define an interior space; positioning a
plurality of tubes in the internal space; forming a baffle from the
first side wall; and folding the baffle with respect to the first
side wall and into engagement with at least one of the plurality of
tubes.
19. The method of claim 18, wherein forming the baffle from the
first side wall includes cutting the first side wall.
20. The method of claim 18, further comprising piercing the baffle
to provide a bypass channel through the baffle connecting an inlet
side of the housing with an outlet side of the housing.
21. The method of claim 18, further comprising providing an elastic
element between the baffle and the first side wall, the elastic
element being deformable to allow movement of the baffle in a
direction substantially normal to a flow path of the first working
fluid through the housing.
22. The method of claim 18, further comprising moving the baffle
relative to the first side wall in a direction substantially normal
to a longitudinal axis of one of the plurality of tubes.
23. The method of claim 18, wherein forming the baffle from the
first side wall includes forming a finger extending outwardly from
the baffle, and wherein folding the baffle with respect to the
first side wall and into engagement with the at least one of the
plurality of tubes includes positioning the finger between two of
the plurality of tubes.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to heat exchangers and, more
particularly, to an exhaust gas recirculation cooler, a method of
assembling the same, and a method of operating the same.
SUMMARY
[0002] In some embodiments, the invention provides a heat exchanger
for transferring heat energy between first and second working
fluids. The heat exchanger can include a housing, a number of tubes
extending through the housing, and a baffle integrally formed with
the housing. In some embodiments, the baffle can include a finger
that extends between two of the tubes.
[0003] The present invention also provides a method of
manufacturing a heat exchanger for transferring heat energy between
first and second working fluids that can include the acts of
providing a housing having at least two sides that are connected at
an angle and define an interior space, forming a finger from one
side, positioning a number of tubes in the interior space, and
positioning the finger between two of the tubes. The method can
also include the act of providing a bypass aperture in the finger
such that a working fluid can flow through the finger. In some
embodiments, the method can include the act of forming a number of
fingers and positioning the fingers in the interior space.
[0004] In other embodiments, the invention provides a method of
manufacturing a heat exchanger that can include the acts of
providing a housing having at least two sides that define an
interior space, positioning a number of tubes in the interior
space, forming a baffle from one side of the housing, and folding
the baffle with respect to the one side of the housing into
engagement with at least one of the tubes. The invention can also
include the act of providing an elastic element between the baffle
and the one side of the housing.
[0005] Other aspects of the invention will become apparent by
consideration of the detailed description and accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a perspective view of a portion of a heat
exchanger according to some embodiments of the present
invention.
[0007] FIG. 2 is an exploded perspective view of the heat exchanger
shown in FIG. 1.
[0008] FIG. 3 is a perspective view of an integrated housing and
baffle of the heat exchanger shown in FIG. 1.
[0009] FIG. 4 is a perspective view of an integrated housing and
baffle according to other embodiments of the present invention.
DETAILED DESCRIPTION
[0010] Before any embodiments of the invention are explained in
detail, it is to be understood that the invention is not limited in
its application to the details of construction and the arrangement
of components set forth in the following description or illustrated
in the following drawings. The invention is capable of other
embodiments and of being practiced or of being carried out in
various ways. Also, it is to be understood that the phraseology and
terminology used herein is for the purpose of description and
should not be regarded as limiting. The use of "including,"
"comprising," or "having" and variations thereof herein is meant to
encompass the items listed thereafter and equivalents thereof as
well as additional items.
[0011] Unless specified or limited otherwise, the terms "mounted,"
"connected," "supported," and "coupled" and variations thereof are
used broadly and encompass both direct and indirect mountings,
connections, supports, and couplings. Further, "connected" and
"coupled" are not restricted to physical or mechanical connections
or couplings.
[0012] Also, it is to be understood that phraseology and
terminology used herein with reference to device or element
orientation (such as, for example, terms like "central, "upper,"
"lower," "front," "rear," and the like) are only used to simplify
description of the present invention, and do not alone indicate or
imply that the device or element referred to must have a particular
orientation. In addition, terms such as "first" and "second" are
used herein for purposes of description and are not intended to
indicate or imply relative importance or significance.
[0013] FIGS. 1-3 illustrate a heat exchanger 10 according to some
embodiments of the present invention. In some embodiments,
including the illustrated embodiment of FIGS. 1-3, the heat
exchanger 10 can operate as an exhaust gas recirculation cooler
(EGRC) and can be operated as part of the exhaust system and/or the
emission system of a vehicle. In other embodiments, the heat
exchanger 10 can be used in other (e.g., non-vehicular)
applications, such as, for example, in electronics cooling,
industrial equipment, building heating and air-conditioning, and
the like. In addition, it should be appreciated that the heat
exchanger 10 of the present invention can take many forms, utilize
a wide range of materials, and can be incorporated into various
other systems.
[0014] During operation and as explained in greater detail below,
the heat exchanger 10 can transfer heat energy from a high
temperature first working fluid (e.g., exhaust gas, water, engine
coolant, CO.sub.2, an organic refrigerant, R12, R245fa, R22, R410A,
air, and the like) to a lower temperature second working fluid
(e.g., exhaust gas, water, engine coolant, CO.sub.2, an organic
refrigerant, R12, R245fa, R22, R410A, air, and the like). In
addition, while reference is made herein to transferring heat
energy between two working fluids, in some embodiments of the
present invention, the heat exchanger 10 can operate to transfer
heat energy between three or more fluids. Alternatively or in
addition, the heat exchanger 10 can operate as a recuperator and
can transfer heat energy from a high temperature portion of a
heating circuit to a low temperature portion of the same heating
circuit. In some such embodiments, the heat exchanger 10 can
transfer heat energy from a working fluid traveling through a first
portion of the heat transfer circuit to the same working fluid
traveling through a second portion of the heat transfer
circuit.
[0015] The heat exchanger 10 can include a housing 12 which can
extend along a portion of the length of the heat exchanger 10 and
can cover at least one side of the heat exchanger 10. In some
embodiments, such as the illustrated embodiment of FIGS. 1-3, the
housing 12 can be formed from multiple housing portions 12a, 12b
having two or more sides that at least partially enclose one or
more elements of the heat exchanger 10. The housing portions 12a,
12b can be formed by cutting, stamping, folding, molding,
extrusion, a combination of these or other like forming processes
from metals, metal alloys, composites, thermoresistive plastics,
etc.
[0016] In embodiments such as the illustrated embodiment of FIGS.
1-3 in which the housing 12 includes two or more housing portions
12a, 12b, adjacent housing portions 12a, 12b can be connected
together by soldering, brazing, welding, adhesive or cohesive
bonding material, fasteners, integral latches or tabs, etc. In
still other embodiments, two or more housing portions 12a, 12b can
be at least partially connected by an interference fit. In yet
other embodiments, the housing 12 can be formed from a single
integral piece. Alternatively or in addition, the housing 12 can be
bonded or connected to other portions of the heat exchanger 10 via
soldering, brazing, welding, adhesive or cohesive bonding material,
fasteners, integral latches or tabs, an interference fit, etc.
[0017] In the illustrated embodiment of FIG. 1, the heat exchanger
10 includes three flat tubes 18 supported in the housing 12. In
other embodiments, the heat exchanger 10 can include one, two,
four, five, six, seven, eight, or more tubes 18, each of which can
have a triangular, circular, square or other polygonal, oval, or
irregular cross-sectional shape.
[0018] As shown in FIGS. 1-3, the heat exchanger 10 can include at
least one header 14 positioned at an end 16 of a stack of heat
exchanger tubes 18. In some embodiments, the heat exchanger 10 can
include multiple headers 14 which can be located at either or both
ends of the stack of heat exchanger tubes 18 or at other locations
on the heat exchanger 10.
[0019] As shown in FIG. 1, each of the tubes 18 can be connected to
the header 14 such that a first working fluid flowing through the
heat exchanger 10 is maintained separate from a second working
fluid flowing through the heat exchanger 10. More specifically, the
heat exchanger 10 defines a first flow path (represented by arrows
22 in FIG. 1) for the first working fluid and a second flow path
(represented by arrows 24 in FIG. 1) for a second working fluid.
The first and second flow paths 22, 24 are separated such that the
first working fluid is prevented from entering the second flow path
24 and such that the second working fluid is prevented from
entering the first flow path 22.
[0020] In some embodiments, such as the illustrated embodiment of
FIGS. 1-3, the tubes 18 can be arranged in a stacking direction and
can be connected to the header 14 allowing the first working fluid
to travel into the open ends of the tubes 18 such that the first
flow path 22 extends through at least a portion of the length of
the tubes 18. In some embodiments, the second working fluid travels
across an exterior of the tubes 18. For example, in the illustrated
embodiment of FIGS. 1-3, the second working fluid enters the heat
exchanger 10 between the header 14 and a baffle 30 and travels
through the heat exchanger 10 along the second flow path 24 between
adjacent tubes 18 and between the stack of tubes 18 and the housing
12.
[0021] In other embodiments, the tubes 18 can have other
orientations and configurations and the first and second flow paths
22, 24 can be maintained separate by other types of dividers,
inserts, partitions, and the like. In still other embodiments, the
first flow path 22 can extend through some of the tubes 18 while
the second flow path 24 can extend through other tubes 18.
[0022] In the illustrated embodiment of FIG. 1, the heat exchanger
10 is configured as a parallel-flow heat exchanger such that the
first flow path 22 or a portion of the first flow path 22 is
substantially parallel to the second flow path 24 or a portion of
the second flow path 24. In other embodiments, the heat exchanger
10 can have other configurations and arrangements, such as, for
example, a cross-flow or a counter-flow configuration.
[0023] In the illustrated embodiment of FIG. 1, the heat exchanger
10 is configured as a single-pass heat exchanger with the first
working fluid traveling along the first flow path 22 through at
least one of a number of tubes 18 and with the second working fluid
traveling along the second flow path 24 between adjacent tubes 18.
In other embodiments, the heat exchanger 10 can be configured as a
multi-pass heat exchanger with the first working fluid traveling in
a first pass through one or more of the tubes 18 and then traveling
in a second pass through one or more different tubes 18 in a
direction opposite to the flow direction of the first working fluid
in the first pass. In these embodiments, the second working fluid
can travel along the second flow path 24 between adjacent tubes
18.
[0024] In yet other embodiments, the heat exchanger 10 can be
configured as a multi-pass heat exchanger with the second working
fluid traveling in a first pass between a first pair of adjacent
tubes 18 and then traveling in a second pass between another pair
of adjacent tubes 18 in a direction opposite to the flow direction
of the second working fluid in the first pass. In these
embodiments, the first working fluid can travel along the first
flow path 22 through at least one of the tubes 18.
[0025] In some embodiments, the heat exchanger 10 can include fluid
chambers supported at one end 16 of the stake of the tubes 18, or
alternatively, the heat exchanger 10 can include fluid chambers
supported at both ends 16 of the stack of tubes 18. In some such
embodiments, the header 14 can at least partially define a portion
of one of the chambers. In embodiments having fluid chambers, a
volume of the first working fluid, or alternatively a volume of the
second working fluid can be housed in one of the fluid
chambers.
[0026] As shown in FIGS. 1-3, the header 14 can have apertures 34
sized to receive one or more of the tubes 18. In embodiments such
as the illustrated embodiment of FIGS. 1-3 having a header 14, the
first working fluid flowing along the first flow path 22 can enter
the tubes 18 through apertures 34 formed in the header 14. In these
embodiments, the header 14 can prevent the second working fluid
from entering the tubes 14. In these embodiments, the header 14 can
also direct the second working fluid between adjacent tubes 18 and
can prevent the second working fluid from entering the tubes 18.
The header 14 can also prevent the first working fluid from flowing
between the tubes 18.
[0027] In some embodiments, the heat exchanger 10 can include
inserts 38 to improve heat transfer between the first and second
working fluids as the first and second working fluids travel along
the first and second flow paths 22, 24, respectively. As shown in
FIGS. 1-3, the inserts 38 can be formed separately from and
positioned within the tubes 18. Alternatively or in addition,
inserts 38 can be positioned between adjacent tubes 18. In other
embodiments, inserts 18 can be integrally formed with the tubes 18
and can extend outwardly from outer surfaces 40 of the tubes 18
and/or inwardly from inner surfaces 42 of the tubes 18.
[0028] In the illustrated embodiment of FIG. 1, an insert 38 is
supported in each of the tubes 18, and extends along the entire
length or substantially the entire length of each of the tubes 18
between opposite open ends of the tubes 18. In other embodiments,
an insert 38 can be supported in only one or less than all of the
tubes 18, and the insert(s) 38 can extend substantially the entire
length of the tube(s) 18 between opposite ends of the tube(s) 18,
or alternatively, the insert 38 can extend through the tube(s) 18
along substantially less than the entire length of the tube(s) 18.
In still other embodiments, two or more inserts 38 can be supported
by or in each tube 18.
[0029] In some embodiments, the inserts 38 can be secured to the
tubes 18. In some such embodiments, the inserts 38 are soldered,
brazed, or welded to the tubes 18. In other embodiments, the
inserts 38 can be connected to the tubes 18 in another manner, such
as, for example, by an interference fit, adhesive or cohesive
bonding material, fasteners, etc.
[0030] In some embodiments, the ends of the tubes 18 can be
press-fit into a header 14. In some such embodiments, the ends of
the tubes 18 and the inserts 38 supported in the tubes 18 or
between the tubes 18 can be at least partially deformed when the
tubes 18 and/or the inserts 38 are press-fit into the header 14. In
some such embodiments, the tubes 18 and/or the inserts 38 are
pinched and maintained in compression to secure the tubes 18 and/or
the inserts 38 in a desired orientation and to prevent leaking.
[0031] In the illustrated embodiment of FIGS. 1-3, the inserts 38
are formed from folded or corrugated sheets of metal. In other
embodiments, the inserts 38 can be cast or molded in a desired
shape and can be formed from other materials (e.g., aluminum, iron,
and other metals, composite material, and the like). In still other
embodiments, the inserts 38 can be cut or machined to shape in any
manner, can be extruded or pressed, can be manufactured in any
combination of such operations, and the like.
[0032] The heat exchanger 10 can also include one or more baffles
30 integrally formed with the housing 12 or one of the housing
portions 12a, 12b. The baffles 30 can be positioned along the
length of the heat exchanger 10 and can extend between two or more
of the tubes 18 to direct the flow of the second working fluid
along the second flow path 24 and through the housing 12. In some
embodiments, the baffles 30 can extend inwardly from housing 12
into an interior of the heat exchanger 10 in order to provide
structural support for the tubes 18 and/or the inserts 38.
Alternatively or in addition, the baffle 30 or a portion of the
baffle 30 can at least partially define the second flow path 24. As
illustrated in FIGS. 1-4, the baffle 30 can be integrally formed
with the housing 12 by cutting, stamping, folding, molding,
extrusion, a combination of these or other like forming processes
from metals, metal alloys, composites, thermoresistive plastics,
etc.
[0033] Each of the baffles 30 can include one or more fingers 48,
which extend inwardly into the interior of the housing 12 between
adjacent tubes 18. In the illustrated embodiment of FIGS. 1-3, the
fingers 48 extend into the interior of the housing in a direction
substantially normal to a length of the tubes 18. In other
embodiments, one or more of the fingers 48 can be oriented at acute
angle with respect to the length of the tubes 18. Alternatively or
in addition, the fingers 48 can be contoured to provide additional
surface area to improve heat transfer and/or to generate turbulence
in the second working fluid flowing past the fingers 48.
[0034] As shown in FIGS. 1-3, the number fingers 48 can be equal to
the number of tubes 18 in the stack. Alternatively, one baffle 30
can include only one or two fingers 48 extending downwardly between
the outermost tube(s) 18 and an interior surface of the housing
12.
[0035] In the illustrated embodiment of FIGS. 1-3, the length L of
at least one of the fingers 48 is less than the width W of the
tubes 18 such that the second flow path 24 extends around the
outermost ends of the finger 48. In other embodiments, the length L
of one or more of the fingers 48 can be substantially equal to or
greater than the width W of the tubes 18. In these embodiments,
openings can extend through the fingers 48, or alternatively,
openings can be defined between the fingers 48 and the adjacent
tubes 18 so that the second working fluid can travel along the
second flow path 24 between opposite ends of the heat exchanger
10.
[0036] In some embodiments, the heat exchanger 10 can include a
first baffle 30 located at one end of the heat exchanger 10 and a
second baffle 30 located at the opposite end of the heat exchanger
10. In some such embodiments, the first baffle 30 can be integrally
formed with the first housing portion 12a and can extend into the
interior of the housing 12 from a first direction, and the second
baffle 30 can be integrally formed with the second housing portion
12b and can extend into the interior of the housing 12 from a
second direction. In other embodiments, both the first and second
baffles 30 can be integrally formed with the first housing portion
12a and can extend into the interior of the housing 12 from a first
direction, or alternatively, both the first and second baffles 30
can be integrally formed with the second housing portion 12b and
can extend into the interior of the housing 12 from a second
direction.
[0037] Additional baffles 30 can be positioned along the length of
the heat exchanger 10 and can be integrally formed with the housing
12, or alternatively, can be secured to the housing 12. In some
embodiments, additional baffles 30 are positioned between the
opposite ends of the heat exchanger 10 with a first one of the
additional baffles 30 having fingers 48 extending inwardly into the
interior of the housing 12 from the first housing portion 12a and
with a second one of the additional baffles 30 having fingers 48
extending inwardly into the interior of the housing 12 from the
second housing portion 12a. In these embodiments, the baffles 30
can ensure that the second working fluid flowing along the second
flow path 24 travels through the heat exchanger 10 along a
circuitous or sinusoidal path around the ends of the fingers 48 of
the baffles 30.
[0038] As shown in the embodiments of FIGS. 1-3, the baffles 30 can
include bypass holes 50 so that a first volume of the second
working fluid can travel through the baffles 30 along a generally
linear path, while a second volume of the second fluid 24 travels
along a circuitous around the ends of the fingers 48 of the baffles
30. The bypass holes 50 or similar apertures can be formed by
drilling, punching, piercing, etching, or the like and are not
limited to a particular size or shape.
[0039] FIG. 4 illustrates an alternate embodiment of the heat
exchanger 210 according to the present invention. The heat
exchanger 210 shown in FIG. 4 is similar in many ways to the
illustrated embodiments of FIGS. 1-3 described above. Accordingly,
with the exception of mutually inconsistent features and elements
between the embodiment of FIG. 4 and the embodiments of FIGS. 1-3,
reference is hereby made to the description above accompanying the
embodiments of FIGS. 1-3 for a more complete description of the
features and elements (and the alternatives to the features and
elements) of the embodiment of FIG. 4. Features and elements in the
embodiment of FIG. 4 corresponding to features and elements in the
embodiments of FIGS. 1-3 are numbered in the 200 series.
[0040] In the illustrated embodiment of FIG. 4, the heat exchanger
210 includes a baffle 230 integrally formed with a first housing
portion 212a. As shown in FIG. 4, two slits are formed along
surface of the first housing portion 212a to define an elastic
element 252. In the illustrated embodiment, the baffle 230 is
connected to the elastic element 252 so that the baffle 230 can
move along a generally linear path with respect to the first
housing portion 212a in a direction substantially normal to a
length of the first housing portion 212a. In some embodiments, the
baffle 230 is movably connected to the housing 212 to absorb or at
least partially absorb vibrations and/or expansions and
contractions caused by fluctuating inlet temperatures of the first
and/or second working fluids. The flexibility provided by such a
connection can enhance the structural stability and reduce or
eliminate thermally induced stresses, thereby improving the
performance of the heat exchanger 210.
[0041] The embodiments described above and illustrated in the
figures are presented by way of example only and are not intended
as a limitation upon the concepts and principles of the present
invention. As such, it will be appreciated by one having ordinary
skill in the art that various changes in the elements and their
configuration and arrangement are possible without departing from
the spirit and scope of the present invention.
* * * * *