U.S. patent application number 12/061191 was filed with the patent office on 2009-10-08 for heat exchanger having a contoured insert and method of assembling the same.
Invention is credited to Robert J. Barfknecht, Rifaquat Cheema, Frank M. Grippe, David E. Janke.
Application Number | 20090250201 12/061191 |
Document ID | / |
Family ID | 41132184 |
Filed Date | 2009-10-08 |
United States Patent
Application |
20090250201 |
Kind Code |
A1 |
Grippe; Frank M. ; et
al. |
October 8, 2009 |
HEAT EXCHANGER HAVING A CONTOURED INSERT AND METHOD OF ASSEMBLING
THE SAME
Abstract
The present invention provides a heat exchanger for transferring
heat between a first working fluid and a second working fluid,
including a pair of spaced apart headers, a number of tubes
extending between the pair of headers and providing a flow path for
the first working fluid and being positioned along a flow path for
the second working fluid, and an insert supportable in one of the
tubes and having a fold extending in a direction substantially
parallel to the flow path for the first working fluid through the
tubes. The fold can define first and second legs of the insert. A
dimple can be formed on the first leg and a protrusion can be
formed on the second leg opposite to the dimple on the first
leg.
Inventors: |
Grippe; Frank M.;
(Kansasville, WI) ; Cheema; Rifaquat; (Kenosha,
WI) ; Janke; David E.; (Racine, WI) ;
Barfknecht; Robert J.; (Waterford, WI) |
Correspondence
Address: |
MICHAEL BEST & FRIEDRICH LLP
100 E WISCONSIN AVENUE, Suite 3300
MILWAUKEE
WI
53202
US
|
Family ID: |
41132184 |
Appl. No.: |
12/061191 |
Filed: |
April 2, 2008 |
Current U.S.
Class: |
165/164 |
Current CPC
Class: |
Y10T 29/4935 20150115;
F28F 3/025 20130101; Y10T 29/49391 20150115; F28F 2215/04 20130101;
F28F 13/08 20130101; F28D 7/1684 20130101; F28F 1/40 20130101; F28D
21/0003 20130101; F28F 2215/10 20130101 |
Class at
Publication: |
165/164 |
International
Class: |
F28D 7/00 20060101
F28D007/00 |
Claims
1. A heat exchanger for transferring heat between a first working
fluid and a second working fluid, the heat exchanger comprising: a
pair of spaced apart headers; a plurality of tubes extending
between the pair of headers and providing a flow path for the first
working fluid and being positioned along a flow path for the second
working fluid; and an insert supportable in one of the plurality of
tubes and having a fold extending in a direction substantially
parallel to a length of the one of the plurality of tubes between
the pair of headers, the insert including a plurality of dimples
extending into and spaced along the fold.
2. The heat exchanger of claim 1, wherein the fold defines first
and second legs of the insert, and wherein, at a height of the
first leg between the fold and a distal end of the first leg, a
width between the first and second legs is substantially constant
between opposite ends of the insert spaced apart in the direction
of the fold.
3. The heat exchanger of claim 1, wherein the fold defines first
and second legs of the insert, wherein the dimple extends across
the first leg, and wherein the second leg includes an outwardly
extending protrusion shaped to be matingly receivable in the dimple
of the first leg.
4. The heat exchanger of claim 1, wherein the fold is a first fold,
wherein the insert includes a second fold extending across the
insert in a direction substantially parallel to the first fold, and
wherein at least one of the plurality of dimples extends across a
leg of the insert between the first fold and the second fold.
5. The heat exchanger of claim 1, wherein the insert has as first
side and a second side opposite to the first side, and wherein the
plurality of dimples are formed on the first side and form
protrusions on the second side, the protrusions extending into the
fold.
6. The heat exchanger of claim 1, wherein the flow path for the
first working fluid extends through the plurality of dimples to
provide a circuitous path between opposite ends of the tube.
7. The heat exchanger of claim 1, wherein the plurality of dimples
at least partially define an elastic region moveable relative to
the tube in the direction substantially parallel to the length of
the tube to accommodate thermal expansion of one of the tube and
the insert.
8. The heat exchanger of claim 1, wherein the fold provides a
non-linear spine of the insert.
9. The heat exchanger of claim 1, wherein the heat exchanger is an
exhaust gas recirculation cooler, and wherein the first working
fluid is engine exhaust and the second working fluid is a
coolant.
10. The heat exchanger of claim 1, wherein the fold defines first
and second legs of the insert, wherein the dimple extends across
the first leg at a distance from an inlet to the flow path for the
first working fluid, and wherein a protrusion extends across the
second leg opposite to the dimple of the first leg.
11. The heat exchanger of claim 10, wherein a cross-sectional area
of the flow path for the first working fluid is substantially the
same between the first and second legs at the inlet to the flow
path for the first working fluid and between the dimple and the
protrusion.
12. A heat exchanger for transferring heat between a first working
fluid and a second working fluid, the heat exchanger comprising: a
pair of spaced apart headers; a plurality of tubes extending
between the pair of headers and providing a flow path for the first
working fluid and being positioned along a flow path for the second
working fluid; and an insert supportable in one of the plurality of
tubes and having a fold extending in a direction substantially
parallel to the flow path for the first working fluid through the
plurality of tubes, the fold defining first and second legs of the
insert, a dimple being formed on the first leg and a protrusion
being formed on the second leg opposite to the dimple on the first
leg.
13. The heat exchanger of claim 12, wherein a cross-sectional area
of the flow path for the first working fluid is substantially the
same between the first and second legs at an outlet of the flow
path for the first working fluid and between the dimple and the
protrusion.
14. The heat exchanger of claim 12, wherein the protrusion of the
second leg is shaped to be matingly receivable in the dimple of the
second leg.
15. The heat exchanger of claim 12, wherein the dimple extends into
the fold.
16. The heat exchanger of claim 12, wherein, at a height of the
first leg between the fold and a distal end of the first leg, a
width between the first and second legs is substantially constant
between opposite ends of the insert spaced apart in the direction
of the fold.
17. The heat exchanger of claim 12, wherein the fold is a first
fold, wherein the insert includes a second fold extending across
the insert in the direction substantially parallel to the flow path
for the first working fluid through the plurality of tubes, and
wherein the dimple extends across the first leg between the first
fold and the second fold.
18. The heat exchanger of claim 12, wherein the protrusion is a
first protrusion, wherein the insert has a first side and a second
side opposite to the first side, and wherein the dimple extends
across the first side and forms a second protrusion on the second
side.
19. The heat exchanger of claim 12, wherein the fold provides a
serpentine spine of the insert.
20. The heat exchanger of claim 19, wherein the plurality of
dimples are roll-formed along the insert.
21. The heat exchanger of claim 12, wherein the heat exchanger is
an exhaust gas recirculation cooler, and wherein the first working
fluid is engine exhaust and the second working fluid is a
coolant.
22. A heat exchanger for transferring heat between a first working
fluid and a second working fluid, the heat exchanger comprising: a
pair of spaced apart headers; a plurality of tubes extending
between the pair of headers and providing a flow path for the first
working fluid and being positioned along a flow path for the second
working fluid; and an insert supportable in one of the plurality of
tubes and having a serpentine fold extending in a direction
substantially parallel to a length of the tube between the pair of
headers.
23. The heat exchanger of claim 22, wherein the fold defines first
and second legs of the insert, and wherein, at a height of the
first leg between the fold and a distal end of the first leg, a
width between the first and second legs is substantially constant
between opposite ends of the insert spaced apart in the direction
of the fold.
24. The heat exchanger of claim 22, wherein the fold defines first
and second legs of the insert, wherein a dimple extends across the
first leg, and wherein the second leg includes an outwardly
extending protrusion shaped to be matingly receivable in the dimple
of the first leg.
25. The heat exchanger of claim 22, wherein the fold is a first
fold, wherein the insert includes a second fold extending across
the insert in a direction substantially parallel to the first fold,
and further comprising a dimple extending across the insert between
the first fold and the second fold.
26. The heat exchanger of claim 22, wherein the insert has a first
side and a second side opposite to the first side, and wherein a
dimple is formed on the first side and forms a protrusion on the
second side, the protrusion extending into the fold.
27. The heat exchanger of claim 22, further comprising a plurality
of dimples roll-formed along the insert.
28. The heat exchanger of claim 22, wherein a plurality of dimples
are spaced along the fold.
29. The heat exchanger of claim 22 wherein the heat exchanger is an
exhaust gas recirculation cooler, and wherein the first working
fluid is engine exhaust and the second working fluid is a
coolant.
30. The heat exchanger of claim 22, wherein the fold defines first
and second legs of the insert, wherein a dimple extends across the
first leg at a distance from an inlet to the flow path for the
first working fluid, and wherein a protrusion extends across the
second leg opposite to the dimple of the first leg.
31. The heat exchanger of claim 30, wherein a cross-sectional area
of the flow path for the first working fluid is substantially the
same between the first and second legs at the inlet to the flow
path for the first working fluid and between the dimple and the
protrusion.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to heat exchangers and more
particularly, to an exhaust gas recirculation cooler and a method
of assembling the same.
SUMMARY
[0002] In some embodiments, the present invention provides a heat
exchanger for transferring heat between a first working fluid and a
second working fluid. The heat exchanger can include a pair of
spaced apart headers, a number of tubes extending between the pair
of headers and providing a flow path for the first working fluid
and being positioned along a flow path for the second working
fluid, and an insert supportable in one of the tubes and having a
fold extending in a direction substantially parallel to a length of
the one of the tubes between the pair of headers. The insert can
include a number of dimples extending into and spaced along the
fold.
[0003] The present invention also provides a heat exchanger for
transferring heat between a first working fluid and a second
working fluid including a pair of spaced apart headers, a number of
tubes extending between the pair of headers and providing a flow
path for the first working fluid and being positioned along a flow
path for the second working fluid, and an insert supportable in one
of the tubes and having a fold extending in a direction
substantially parallel to the flow path for the first working fluid
through the tubes. The fold can define first and second legs of the
insert. A dimple can be formed on the first leg and a protrusion
can be formed on the second leg opposite to the dimple on the first
leg.
[0004] In some embodiments, the present invention provides a heat
exchanger for transferring heat between a first working fluid and a
second working fluid including a pair of spaced apart headers, a
number of tubes extending between the pair of headers and providing
a flow path for the first working fluid and being positioned along
a flow path for the second working fluid, and an insert supportable
in one of the tubes and having a serpentine fold extending in a
direction substantially parallel to a length of the tube between
the pair of headers.
[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 bottom perspective view of a heat exchanger
according to some embodiments of the present invention.
[0007] FIG. 2 is a partially cut-away view of a portion of the heat
exchanger shown in FIG. 1.
[0008] FIG. 3 is an exploded perspective view of a portion of a
tube and an insert of the heat exchanger shown in FIG. 1.
[0009] FIG. 4 is a perspective view of a portion of the insert
shown in FIG. 3.
[0010] FIG. 5 is an exploded perspective view of a portion of a
tube and an insert according to an alternate embodiment of the
present invention.
[0011] FIG. 6 is a perspective view of a portion of the insert
shown in FIG. 5.
[0012] FIG. 7 is a top view of a partially formed insert that can
be manufactured according to the method shown in FIG. 9.
[0013] FIG. 8 is a perspective view of a partially formed insert
that can be manufactured according to the method shown in FIG.
10.
[0014] FIG. 9 illustrates a method for forming the insert shown in
FIG. 5.
[0015] FIG. 10 illustrates another method for forming the insert
shown in FIG. 5.
[0016] FIG. 11 is a perspective view of a section of the insert
forming device shown in FIG. 10.
DETAILED DESCRIPTION
[0017] 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.
[0018] 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.
[0019] 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.
[0020] FIGS. 1-4 illustrate a heat exchanger 10 according to some
embodiments of the present invention. In some embodiments,
including the illustrated embodiments of FIGS. 1-4, the heat
exchanger 10 can operate as an exhaust gas recirculation cooler
(EGRC) and can be operated with the exhaust 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.
[0021] During operation and as explained in greater detail below,
the heat exchanger 10 can transfer heat from a high temperature
first working fluid (e.g., exhaust gas, water, engine coolant,
CO.sub.2, an organic refrigerant, R12, R245fa, air, and the like)
to a lower temperature second working fluid (e.g., water, engine
coolant, CO.sub.2, an organic refrigerant, R12, R245fa, air, and
the like). In addition, while reference is made herein to
transferring heat between two working fluids, in some embodiments
of the present invention, the heat exchanger 10 can operate to
transfer heat between three or more fluids. Alternatively or in
addition, the heat exchanger 10 can operate as a recuperator and
can transfer heat from a high temperature location of a heating
circuit to a low temperature location of the same heating circuit.
In some such embodiments, the heat exchanger 10 can transfer heat
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.
[0022] As shown in FIGS. 1 and 2, the heat exchanger 10 can include
a first header 18 and a second header 20 positioned at respective
first and second ends 22, 24 of a stack of heat exchanger tubes 26
having outer surfaces 28 (shown in FIGS. 1, 3, and 5). In the
illustrated embodiment of FIGS. 1-4, the first end 22 is secured to
a first collecting tank 30 and the second end 24 is secured to a
second collecting tank 32. In other embodiments, the heat exchanger
10 can include a single header 18 and/or a single tank 30 located
at one of the first and second ends 22, 24 or at another location
on the heat exchanger 10.
[0023] As shown in FIGS. 1 and 2, each of the tubes 26 can be
secured to the first and second headers 18, 20 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 34 in FIG. 1) for the first
working fluid and a second flow path (represented by arrows 36 in
FIG. 1) for a second working fluid, and the first and second flow
paths 34, 36 are separated such that the first working fluid is
prevented from entering the second flow path 36 and such that the
second working fluid is prevented from entering the first flow path
34.
[0024] In some embodiments, such as the illustrated embodiment, the
tubes 26 are secured to the first and second headers 18, 20 and the
first and second tanks 30, 32 such that the first working fluid
enters the heat exchanger 10 through a first inlet aperture 40 in
the first tank 30, travels through the tubes 26 of the heat
exchanger 10 along the first flow path 34, and is prevented from
entering the second flow path 36. In these embodiments, the tubes
26 can be secured to the first and second headers 18, 20 and the
first and second tanks 30, 32 such that the second working fluid
enters the heat exchanger 10 through a second inlet aperture 42 in
the second tank 32, travels through the heat exchanger 10 along the
second flow path 36 between the tubes 26, and is prevented from
entering the first flow path 34.
[0025] In other embodiments, the tubes 26 can have other
orientations and configurations and the first and second flow paths
34, 36 can be maintained separate by dividers, inserts, partitions,
and the like. In still other embodiments, the first flow path 34
can extend through some of the tubes 26 while the second flow path
36 can extend through other tubes 26.
[0026] As shown in FIG. 2, the headers 18, 20 can have apertures
sized to receive one or more of the tubes 26. As illustrated by
FIGS. 1 and 2, the first working fluid flowing along the first flow
path 34 can enter the tubes 26 through apertures formed in the
first header 18. In these embodiments, the first header 18 can also
direct the second working fluid from the second inlet aperture 42
between adjacent tubes 26 and can prevent the second working fluid
from flowing into the tubes 26. The first header 18 can also
prevent the first working fluid from flowing between the tubes
26.
[0027] In the illustrated embodiment, the heat exchanger 10 is
configured as a cross-flow heat exchanger such that the first flow
path 34 or a portion of the first flow path 34 is opposite to the
second flow path 36 or a portion of the second flow path 36. In
other embodiments, the heat exchanger 10 can have other
configurations and arrangements, such as, for example, a
parallel-flow or a counter-flow configuration.
[0028] In the illustrated embodiment, the heat exchanger 10 is
configured as a single-pass heat exchanger with the first working
fluid traveling along the first flow path 34 through at least one
of a number of tubes 26 and with the second working fluid traveling
along the second flow path 36 between adjacent tubes 26. 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 26 and then traveling
in a second pass through one or more different tubes 26 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 36 between adjacent tubes
26.
[0029] 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 26 and then traveling in a second pass between another pair
of adjacent tubes 26 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 34 through at least one of the tubes 26.
[0030] In the illustrated embodiment, the heat exchanger 10
includes seven tubes 26, each of which has a substantially
rectangular cross-sectional shape. In other embodiments, the heat
exchanger 10 can include one, two, three, four, five, six, eight,
or more tubes 26, each of which can have a triangular, circular,
square or other polygonal, oval, or irregular cross-sectional
shape.
[0031] As mentioned above, in some embodiments, the second flow
path 36 or a portion of the second flow path 36 can extend across
the outer surface 28 of one or more of the tubes 26. In some such
embodiments, ribs 56 (see FIG. 3) can be formed along the outer
surfaces 28 of the tubes 26 to at least partially define channels
58 between adjacent tubes 26. Alternatively, as shown in FIG. 5,
the tubes 26 of the heat exchanger 10 can be generally oval shaped
(i.e., a simple extruded tube) and devoid of ribs 56 defining
channels 58. A housing can be provided around the tubes 26 to
prevent the second fluid from leaking out of the heat exchanger 10
between adjacent tubes 26. In such an embodiment, the housing would
define the second flow path 36 between/around the tubes 26.
[0032] In embodiments, such as the illustrated embodiment of FIGS.
1-4, having outwardly extending ribs 56, the ribs 56 of each tube
26 can be secured to an adjacent tube 26. In some such embodiments,
the ribs 56 of one tube 26 can be soldered, brazed, or welded to an
adjacent tube 26. In other embodiments, adjacent tubes 26 can be
secured together with inter-engaging fasteners, other conventional
fasteners, adhesive or cohesive bonding material, by an
interference fit, etc. In addition, a housing can be provided
around the tubes 26 of the embodiment illustrated in FIGS. 1-4.
[0033] Additional elevations, recesses, or deformations 64 can also
or alternatively be provided on the outer surfaces 28 of the tubes
26 to provide structural support to the heat exchanger 10, prevent
the deformation or crushing of one or more tubes 26, maintain a
desired spacing between adjacent tubes 26, improve heat exchange
between the first and second working fluids, and/or generate
turbulence along one or both of the first and second flow paths 34,
36.
[0034] The heat exchanger 10 can include inserts 66, which 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 34, 36, respectively. The inserts 66 can provide the
heat exchanger core (i.e., the tubes 26) with increased surface
area for distribution of the heat provided by the first and/or
second working fluids. As shown in FIGS. 2, 3, and 5, the inserts
66 can be positioned in the tubes 26. Alternatively or in addition,
inserts 66 can be positioned between adjacent tubes 26. In other
embodiments, inserts 66 can be integrally formed with the tubes 26
and can extend outwardly from the outer surfaces 28 of the tubes
26, or alternatively, inwardly from inner surfaces of the tubes 26.
In some embodiments, the inserts 66 can improve the durability and
strength of the heat exchanger 10. The configurations (geometrical
and topographical) of the inserts 66 can be such that the expansion
and contraction experienced by the material due to thermal
fluctuations can be compensated for with increased flexibility
(discussed in further detail below).
[0035] In the illustrated embodiment of FIG. 2, an insert 66 is
supported in each of the tubes 26, and extends along the entire
length or substantially the entire length of each of the tubes 26
between opposite ends 68 of the tubes 26. As FIG. 2 illustrates,
the insert 66 can also or alternatively extend across the entire
width or substantially the entire width of each of the tubes 26
between opposite sides of the tubes 26. In other embodiments, an
insert 26 can be supported in only one or less than all of the
tubes 26, and the insert(s) 66 can extend substantially the entire
length of the tube(s) 26 between opposite ends 68 of the tube(s)
26, or alternatively, the insert 66 can extend through the tube(s)
26 along substantially less than the entire length of the tube(s)
26. In still other embodiments, two or more inserts 66 can be
supported by or in each tube 26. In some embodiments, the inserts
66 can be secured to the tubes 26. In some such embodiments, the
inserts 66 are soldered, brazed, or welded to the tubes 26. In
other embodiments, the inserts 26 can be connected to the tubes 26
in another manner, such as, for example, by an interference fit,
adhesive or cohesive bonding material, fasteners, etc.
[0036] In some embodiments, the ends 68 of the tubes 26 can be
press-fit into one or both of the first and second headers 18, 20.
In some such embodiments, the ends 68 of the tubes 26 and the
inserts 66 supported in the tubes 26 or between the tubes 26 can be
at least partially deformed when the tubes 26 and/or the inserts 66
are press-fit into the first and/or second headers 18, 20. As such,
the tubes 26 and/or the inserts 66 are pinched and maintained in
compression to secure the tubes 26 and/or the inserts 66 in a
desired orientation and to prevent leaking. In some embodiments,
the tubes 26 can be brazed, soldered, or welded to the first and/or
second headers 18, 20.
[0037] In the illustrated embodiments, roll-formed sheets of metal
are folded to form the inserts 66 in a method that will be
described in further detail below. In other embodiments, the
inserts 66 can be cast or molded in a desired shape and can be
formed from other materials (e.g., aluminum, copper, iron, and
other metals, composite material, alloys, and the like). In still
other embodiments, the inserts 66 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.
[0038] As most clearly shown in FIGS. 3 and 7, the insert 66 can be
corrugated and have an overall length L, width W, and height H. The
length L of the insert 66 is defined as the general direction of
fluid flow within the tube 26 (i.e., from the first header 18 to
the second header 20). As shown in the embodiment illustrated in
FIG. 3, each fold forms a serpentine spine 76 that extends
generally in parallel to the length L of the insert 66.
[0039] The illustrated embodiment of the insert 66 includes a
series of parallel-running spines 76 that form alternating peaks 78
and valleys 80 along the width W of the insert 66. As shown in FIG.
2, the peaks 78 and valleys 80 can engage respective upper and
lower interior sides (e.g., between upper and lower sides in FIGS.
2, 3, and 5) of a tube 26. In the illustrated embodiment, legs or
flanks 82 extend between each pair of adjacent folds (i.e., from a
peak 78 to a valley 80 or vice versa) along the length L, to give
the insert 66 a height H. In addition, the inserts 66 of some
embodiments can have pointed, squared, or irregularly shaped peaks
78 and/or valleys 80. The resulting lateral edge of the insert 66
of the illustrated embodiment, as shown in FIGS. 2 and 3 can be
generally wavy. However, in other embodiments, the lateral edge can
be generally sinusoidal or saw-toothed, among other shapes. The
structural elements formed by each fold 76 of the corrugated insert
66 are described more specifically with reference to FIGS. 4 and 6
below.
[0040] As illustrated by FIGS. 4 and 6, a first leg 82a can be at
least partially defined on one side of a spine 76 and a second leg
82b can be at least partially defined on the other side of the
spine 76. Fold 76a is positioned immediately adjacent to the first
leg 82a and defines a height h of the leg 82a. Similarly, fold 76b
is positioned at the distal end of the second leg 76b, which has
the same height h. The space S between adjacent legs 82a, 82b is
defined as the distance between the points located at the same
distance along length L and height h of each leg 82. The legs 82 of
the insert 66 can also have various topographical configurations.
For example, at one point along the length L, the legs 82 can be
contoured or wavy (i.e., when viewed from an end of the insert 66
as shown in FIGS. 3 and 4, and at another point along the length L,
the legs 82 can be straight.
[0041] As shown in FIGS. 3-8, the legs 82 can include contour
elements such as dimples 86 and protrusions 88 spaced along their
length L. These elements are deformations in the material that
forms the insert 66 and do not pierce or provide connections
between opposite sides of the insert 66. In some such embodiments,
a dimple 86 formed on one side of a leg 82 can consequently form a
protrusion 88 on the opposite side of the leg 82 (i.e., a dimple 86
is a geometric complement of protrusion 88). The contour elements
formed in the insert 66 can appear as pyramid, frustum, prism,
and/or hemispheroid-like projections or dimples, among others. In
the illustrated embodiment, the contour elements each have two
planes of symmetry (one of which is the length L, space s plane,
and the other of which is the height h, space s plane). As such,
the upper half of the contour element is a mirror image of the
bottom half (with respect to the height h of the leg 82 it is
positioned on). Similarly, the left half of the contour element is
a mirror image of the right half (with respect to the length L of
the leg 82 it is positioned on). In some embodiments, a protrusion
86 in one leg 82 can be positioned such that it is at least
partially receivable in a dimple 88 in an adjacent to leg 82 (i.e.,
at the same distance along height h and length L of each leg ).
[0042] In some embodiments, contour elements can extend along the
entire height h of the leg 82 from one fold 76 to an adjacent fold
76 (i.e., from a peak 78 to an adjacent valley 80 or vice versa).
Each contour element has a width d, as shown in FIG. 6. In the
illustrated embodiment, the width d also indicates the spacing
between similar contour elements. In other embodiments, the spacing
between similar contour elements can be greater than the width d of
an intervening or alternating contour element.
[0043] As shown in FIG. 4, the serpentine shape of the spine 76 is
determined by the geometry and placement of the dimples 86 and
protrusions 88. In the illustrated embodiments, dimples 86 are
alternated with protrusions 88 along the length L of each leg 82,
and each of the contours extends between adjacent folds 76.
Accordingly, a number of dimples 86 and a number of protrusions 88
can be spaced along the edge of each fold 76. FIG. 4 includes
reference measurements to more clearly illustrate the geometry of
the insert 66. Specifically, reference a indicates the distance
between the midline of the fold 76 and the edge of a dimple 86,
reference b indicates the distance between the midline of the fold
76 and the edge of a protrusion 88, and reference c indicates the
lateral distance (i.e., the direction normal to the length L of the
insert and width d of the contour element) from the edge of the
contour element at the fold 76, to its outermost
point/extension.
[0044] As illustrated in FIGS. 3-6, an insert 66 formed with
longitudinal rows of alternating contour elements 86, 88, can be
folded such that the space S between adjacent legs 82 at a
particular height h can be generally constant along their length L.
Thus, the flow path cross-sectional area is essentially constant
along the length L between opposite ends 68 of the tube 26.
Accordingly, the first flow path 34 is made circuitous and is
consequently longer than a straighter flow path. Such an insert
configuration can increase turbulence of the working fluid and
consequently allow for more efficient heat transfer without causing
significant pressure changes/buildup along the length L of the
insert 66. Additionally, contour elements formed in the inserts 66
can impact the shape of the spine 76. For example, FIGS. 3-8 show
how a pattern of dimples 86 and protrusions 88- specifically
longitudinal rows of the continuously alternating contour
elements--can create a serpentine-shaped spine 76. As such, even
the flow path immediately adjacent to the inner surfaces of the
tube 26 is elongated and made circuitous. The serpentine shape of
the spine 76 can also provide a reinforced connection between the
tube 26 and the insert 66 which can also improve heat transfer.
[0045] In embodiments having inserts 66 with wavy or contoured
cross-sections, such as the illustrated embodiments, the inserts 66
operate as elastic members to absorb or at least partially absorb
vibrations and/or to absorb expansions and contractions of the
inserts 66 caused by fluctuating temperatures of the first and/or
second working fluids. In some such embodiments, the elasticity of
the contoured inserts 66 prevents or reduces cracking and breaking
of the inserts 66. Alternatively or in addition, the elasticity of
the contoured inserts 66 prevents and/or reduces cracking and
breaking of connections (e.g., solder points, braze points, weld
points, etc.) between the spines 76 of the inserts 66 and the
interior sides of the tubes 26.
[0046] As shown in FIGS. 5-8, in some embodiments, contours 86, 88
can extend continuously from a first lateral edge 92 to a second
lateral edge 94, along the length L of a leg 82. In other
embodiments, such as those illustrated in FIGS. 2-4, contours only
extend continuously along the length L of a middle portion of the
insert 66, while the edges 92, 94 have a different topographical
configuration, such as, for example, wavy. The contoured portion
can allow for changes in length L (i.e., longitudinal flexibility),
while the wavy edges can compensate for changes in height h of the
legs 82 (i.e., vertical flexibility). This can be desirable in
embodiments where the height of the insert H is constrained by
connection to the inner surfaces of the tube 26, especially where
the tube ends 68 are further constrained by the first and second
headers 18, 20.
[0047] FIG. 9 illustrates a method of forming an insert 66 for a
heat exchanger 10 according to some embodiments of the present
invention. The method involves roll-forming a pattern of dimples 86
and protrusions 88 into a sheet of deformable heat conducting
material 100 (e.g, aluminum, copper, bronze, and alloys including
one or more of these metals). To clarify the description, the
process of contour formation is shown in FIG. 9 (and discussed with
reference to FIG. 9) as occurring in two distinct and consecutive
steps for a particular longitudinally-located, lateral section of
the sheet. First, at the right-hand side of the figure, dimples 86
are roll-formed, then, to the left of that, protrusions 88 are
roll-formed. However, in practice, roll-formation of dimples 86 and
protrusions 88 can be executed simultaneously (as described and
illustrated with respect to the alternative embodiments shown in
FIGS. 10 and 11 below). Whether the dimples 86 and protrusions 88
are formed consecutively or simultaneously, the roll-formed insert
66 in FIG. 9 then undergoes a folding process (right-hand side of
the figure) to create spines 76. The steps discussed above can be
incorporated into a high-speed assembly process which is described
in more detail below.
[0048] As shown in FIG. 9, the method can make use of a first
cylindrically-shaped roller 102 having projections 104 positioned
in longitudinal rows along its curved exterior surface 106. The
first roller 102 can be rotated about its axis 108 as it makes
contact with a first side 110 of the sheet of deformable material
100, positioned tangentially with respect to the curved surface
106. The weight of the first roller 102 can be used to exert
pressure on the deformable material such that the projections 104
form dimples 86 in the material 100. In other embodiments, the
sheet of material 100 can be forced into contact with the roller
100 by other means to form dimples 86.
[0049] The shape and size of the projections 104 with respect to
the thickness of the sheet of material 100 can be such that the
dimples 86 formed by contact of projections 104 with the first side
110 of the sheet of deformable material 100 create their geometric
complement on a second side (not visible) of the sheet 100 which is
opposite to the first side 110. Thus, dimples 86 and protrusions 88
can be simultaneously formed on the first side 110 and an opposite
second side of the sheet 100, respectively.
[0050] A second cylindrically-shaped roller 112 having projections
114 positioned in longitudinal rows along its curved surface 116
can be positioned adjacent to the opposite side of the sheet 100
from the first roller 102. The second roller 112 can also be
rotated about its axis 118 as it makes contact with the second side
of the sheet of deformable material 100, positioned tangentially
with respect to the curved surface 116. In this way, dimples 86 can
be formed on the second side of the sheet 100, and corresponding
projections 88 can be formed on the first side 110.
[0051] The rollers 102, 112 can be formed by axially stacking
cylindrical disks, the boundaries of which are illustrated by
dashed lines in FIG. 9. In some embodiments, disks with various
shaped projections 114 and/or circumferential spacing between
projections 114 can be assembled into a roller that will form
inserts 66 with different dimensions and geographies. Similarly,
the disks can be circumferentially staggered to provide inserts 66
with more or less space between rows of contour elements, which can
result in wider or narrower spines 76. The rollers 102, 112 can be
arranged with respect to each other such that the dimples 86 and
protrusions 88 on each side of the sheet are formed at specific
locations with respect to each other. For example, FIGS. 7-9
illustrate how the rollers 102, 112 can be aligned to form lateral
and longitudinal rows of alternating dimples 86 and protrusions 88
along the sheet 100. The lateral rows are separated by narrow gaps
where the sheet 100 can be folded to form corrugations such that
the lateral rows become legs 82 and the gaps become spines 76. In
the illustrated embodiment, the rollers 102, 112 are staggered
slightly to form serpentine-shaped spines 76. In other embodiments,
the rollers 102, 112 can be aligned to form straight spines 76. In
still other embodiments, the positioning, size, and/or shape of the
projections 104, 114 on the first and/or second rollers 102, 112
can be varied to change the geometry and/or topography of the
insert 66. In still other embodiments, curved surfaces 106, 116 of
the rollers 102, 112 can be provided with indentions corresponding
(i.e., in location, size, shape, etc.) to the projections 114, 104
in the opposing roller 112, 102, in order to better define the
contours formed in the sheet 100.
[0052] FIG. 10 illustrates a method of forming inserts 66 according
to another embodiment of the invention. The method illustrated in
FIG. 10 uses star-shaped rollers to simultaneously form contour
elements and partially fold the insert 66. A first star-shaped disk
120 represents a first star-shaped roller that is positioned on a
first side 110 of a sheet of deformable material 100 in the
illustrated embodiment of FIG. 10. Along the circumference of the
first disk 120, alternating ridges 122 and crevasses 124 create the
star shape of the disk. The ridges 122 and crevasses 124 can
contribute to the formation of peaks 78 and valleys 80 as will be
described in further detail below. Between each ridge 122 and
crevasse 124 is formed a projection 126 or an indention 128. The
projections 126 and indentions 128 can form dimples 86 and
protrusions 88 in the insert as will also be discussed in further
detail below. In some embodiments, such as the illustrated
embodiment, the projections 126 and indentions 128 can be geometric
complements and have multiple planes of symmetry as discussed
previously with respect to dimples 86 and protrusions 88. In other
embodiments, the ridges 122 can be geometric complements of
crevasses 124.
[0053] A second star-shaped disk 130 in FIG. 10 represents a second
star-shaped roller that can have alternating ridges 132 and
crevasses 134 that separate alternating projections 136 and
indentions 138 similar (i.e., in shape, size, etc.) to those of the
first disk 120. Alternatively or in addition, the projections 136
can be geometric complements of indentions 128 and projections 126
can be geometric complements of indentions 138, in which case,
projections 126, 136 need not be geometric complements of
indentions 128, 138 on the same disk. The second star-shaped disk
130 is positioned on a second side 140 of the sheet of material
100.
[0054] The first and second star-shaped disks 120, 130 can be
positioned with respect to each other such that each ridge 122 of
the first disk 120 fits within a crevasse 134 of the second disk
130 and each ridge 132 of the second disk 130 fits within a
crevasse 124 of the first disk 120 as the disks 120, 130 turn on
their respective axes. Thus, when the sheet of deformable material
100 is fed between the star-shaped disks 120, 130, the
corresponding ridges 122 and crevasses 134 fold the material to
form peaks 78, and corresponding ridges 132 and crevasses 124 fold
the material to form valleys 80. Similarly, the projections 126,
136 and corresponding indentions 138, 128 form dimples 86 and
protrusions 88 in the insert 66.
[0055] Star-shaped rollers can be made up of star-shaped disks 120
that are stacked axially, similar to the arrangement discussed
above with respect to the embodiment of FIG. 9. FIG. 11 illustrates
how these star-shaped disks 120 can be stacked in an alternating
arrangement such that a projection 126 in one disk is positioned
adjacent an indention 128 in a second disk. Adjacent disks can be
staggered such that the ridges 122 and crevasses 124 in one disk
are not in direct alignment with the ridges 122 and crevasses 124
in a second disk, as shown in FIG. 11. By complementary positioning
of two star-shaped rolls having this arrangement of disks, an
insert 66 can be formed having serpentine spines 76, as shown in
FIGS. 3-8.
[0056] After the inserts 66 have been roll-formed and folded, they
can be cut to the appropriate size and then inserted into tubes 26.
In other embodiments, the inserts 66 can be cut before they are
folded. Alternatively, the tubes 26 can be assembled around the
inserts 66. In still other embodiments, the tubes 26 and the
inserts 66 can be cut to size simultaneously.
[0057] 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.
* * * * *