U.S. patent application number 10/004376 was filed with the patent office on 2003-04-24 for exchanger of thermal energy with multiple cores and a thermal barrier.
This patent application is currently assigned to Heatcraft, Inc.. Invention is credited to Prater, Larry P., Stoynoff, Richard P., Wayne, Steven Falko.
Application Number | 20030075307 10/004376 |
Document ID | / |
Family ID | 21710494 |
Filed Date | 2003-04-24 |
United States Patent
Application |
20030075307 |
Kind Code |
A1 |
Stoynoff, Richard P. ; et
al. |
April 24, 2003 |
Exchanger of thermal energy with multiple cores and a thermal
barrier
Abstract
An exchanger of thermal energy with multiple cores and a thermal
barrier. The first core (e.g. a condenser) 12 has a first fin 16.
Disposed in juxtaposition with the first core 12 is a second core
(e.g. a radiator) 30 that is located downstream thereof in relation
to ambient air flow. The cores 12 and 30 respectfully have first
and second fins 16, 34 that are connected by a thermal fuse which
provides stability during assembly, but which can be degradable.
Separating the first and second fins 16, 34 is a thermal break
comprising a slit 50 that is formed without removal of material,
thereby inhibiting the flow of heat energy across the fins between
the first 12 and second 30 heat exchanger cores.
Inventors: |
Stoynoff, Richard P.;
(Woodhaven, MI) ; Wayne, Steven Falko; (Rochester
Hills, MI) ; Prater, Larry P.; (Taylor, MI) |
Correspondence
Address: |
BROOKS & KUSHMAN
1000 TOWN CENTER 22ND FL
SOUTHFIELD
MI
48075
|
Assignee: |
Heatcraft, Inc.
Grenada
MS
|
Family ID: |
21710494 |
Appl. No.: |
10/004376 |
Filed: |
October 22, 2001 |
Current U.S.
Class: |
165/135 ;
165/140 |
Current CPC
Class: |
F28F 1/126 20130101;
F28D 1/0435 20130101; F28F 2009/004 20130101; F28F 13/00 20130101;
F28F 2270/00 20130101; F28F 2215/02 20130101 |
Class at
Publication: |
165/135 ;
165/140 |
International
Class: |
F28F 013/00; F28D
007/10 |
Claims
What is claimed is:
1. A multiple core exchanger of thermal energy, through which a
medium passes to exchange thermal energy with fluid flowing through
channels of one or more of the multiple cores of the multiple core
exchanger of thermal energy, the multiple core exchanger of thermal
energy comprising: a first core having a plurality of first
channels through which a first fluid flows and a first fin disposed
between at least some of the first channels to facilitate an
exchange of thermal energy between the first fluid and the medium;
a second core in thermal communication with the first core, the
second core having a plurality of second channels through which a
second fluid flows and a second fin disposed between at least some
of the second channels to facilitate an exchange of thermal energy
between the second fluid and the medium; the second fin being
integrally formed with the first fin so that the second fin has a
shape which complements that of the first fin; and a thermal break
comprising a slit.
2. The multiple exchanger of thermal energy of claim 1, further
having: a thermal fuse which locally connects the first and the
second fins between adjacent edges of the first and second
fins.
3. The multiple core exchanger of thermal energy of claim 1,
further comprising: at least one louver defined within one or more
of the fins extending at least partially between a pair of opposing
edges thereof;
4. The multiple core exchanger of thermal energy of claim 1,
wherein the first and second cores respectively serve as a
condenser and a radiator; the first fin has a width (L.sub.1); the
second fin has a width (L.sub.2); and L.sub.1 is less than or equal
to L.sub.2.
5. The multiple core exchanger of thermal energy of claim 1,
wherein the first and second cores respectively serve as a
condenser and a radiator; the first fin has a width (L.sub.1); the
second fin has a width (L.sub.2); and L.sub.1 is greater than
L.sub.2.
6. The multiple core exchanger of thermal energy of claim 1,
wherein the first core and the second core are selected from one or
more of the group consisting of an oil cooler, a transmission
cooler, a radiator, a condenser, a charge air cooler, an
evaporator, a heater core, and combinations thereof.
7. The multiple core exchanger of thermal energy of claim 2,
wherein the thermal fuse is formed of a generally rectangular
section of material having an edge (X) and an edge (Y) wherein the
length of X is greater than or equal to that of Y.
8. The multiple core exchanger of thermal energy of claim 2,
wherein the thermal fuse is formed of a generally rectangular
section of material having an edge (X) and an edge (Y) wherein the
length of X is less than that of Y.
9. The multiple core exchanger of thermal energy of claim 2,
wherein the thermal fuse is formed of edges which are
curvilinear.
10. The multiple core exchanger of thermal energy of claim 2,
wherein the thermal fuse is formed of an homogeneous material.
11. The multiple core exchanger of thermal energy of claim 2,
wherein the thermal fuse is formed of a non-homogeneous
material.
12. The multiple exchanger of thermal energy of claim 2, wherein
the thermal fuse comprises a portion of material continuity for
promoting stability during construction of the exchanger of thermal
energy, the material continuity having the characteristic of being
frangible.
13. The multiple core exchanger of thermal energy of claim 3,
wherein at least some of the at least one louvers are situated
other at least partially across the elongated strip, opposing
arrays being separated from each other by the thermal break.
14. The multiple core exchanger of thermal energy of claim 3,
wherein the at least one louver is located within only one of the
cores.
15. A multiple core heat exchanger through which a cooling medium
passes comprising: a first heat exchanger core having a plurality
of first channels through which a first fluid flows and a first fin
disposed between adjacent first channels to facilitate heat
exchange between the first fluid and the cooling medium, the first
fin having a corrugated shape including first upper folds, first
lower folds, a first wall extending between one of the first upper
folds and one of the first lower folds, and a first array of
louvers extending from the first wall; a second heat exchanger core
disposed downstream of the first heat exchanger core, the second
heat exchanger core having a plurality of second channels through
which a second fluid flows and a second fin disposed between
adjacent second channels to facilitate heat exchange between the
second fluid and the cooling medium, the second channels extending
substantially parallel with the first channels, the second fin
being integrally formed with the first fin so that the second fin
also has a corrugated shape with second upper folds, second lower
folds and a second wall which connects one of the second upper
folds and one of the second lower folds, and a second array of
louvers extending from the second wall; a thermal break comprising
a slit formed without removal of material between the first and
second upper and lower folds, and the first and second walls,
thereby inhibiting the flow of heat energy across the first and
second fins; and a thermal fuse which locally connects the first
and the second fins.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a multiple core exchanger of
thermal energy having corrugated fins that are provided with a
thermal barrier comprising a longitudinal slit formed without
removal of material for impeding the flow of heat thereacross and
bridges that locally connect material across the slit for promoting
stability during construction of the heat exchanger and in
service.
[0003] 2. Background Art
[0004] In the field of exchangers of thermal energy, and more
particularly of heat exchangers, louvers deflect or direct a fluid
such as air and channel heat or coldness from a source. In older
designs, little turbulation actually occurs, and laminar flow is
relatively uninterrupted. Over the years, a louvered serpentine fin
in heat exchangers has undergone design changes to optimize its
contribution to the process of exchanging heat between, for
example, a radiator and a condenser in the automotive field. Louver
width has varied, as has its angle. Louver length has increased,
bend radii have changed, and louver patterns have been experimented
with in continued efforts to improve the efficiency of the heat
exchange process.
[0005] It is known that the more the heating or cooling media can
be turbulated, the more efficient the exchanger of thermal energy.
One reason is the disturbance of boundary layers of stagnant media
from which little thermal energy can be extracted. One approach is
disclosed in commonly owned U.S. Pat. No. 5,738,169, which is
incorporated by reference herein.
[0006] A related need in the ideal turbulating louver is structural
strength. But to realize manufacturing economics, the heat exchange
industry has reduced the thickness of its fin material.
[0007] U.S. Pat. No. 6,213,196 discloses a double heat exchanger
that combines a condenser of a refrigeration cycle for a vehicle
air conditioner and a radiator for cooling engine coolant. That
patent is incorporated herein by reference. The reference teaches
that in double heat exchangers, plural condenser tubes and plural
radiator tubes can be arranged in a vertical direction at the same
pitch. The height of each of the radiator tubes is larger than that
of the condenser tubes in the vertical direction. Accordingly, the
height of the condenser fin disposed between adjacent condenser
tubes needs to be larger than that of the radiator fin disposed
between adjacent radiator tubes in the vertical direction. '196
patent, col. 1, 11. 20-34. That reference teaches also that the
heights of the fins associated with the first and second heat
exchangers differ. Id., col. 2, 11. 31-33.
[0008] It is known that dual-purpose fins exist in which slots have
been introduced into the fin strip in order to inhibit heat
transfer. Such slots require the removal of material from the fin
strip before fin formation can be completed. Slug removal requires
an additional operation and creates problems which include the
expense of additional machinery and decreased fin speed production.
There is also the possibility that if a blanking process is coupled
with the fin-forming process, a slug of scrap material could find
its way into the fin roll and damage it, or jam the fin-forming
machine. Additionally, the unwanted presence of such debris could
adversely interfere with the brazing or core-building process.
[0009] Following conventional teachings (such as those disclosed in
the '196 patent), each heat exchanger in a double exchanger
configuration is brazed before assembly. The thermal break between
the condenser and radiator is defined by mechanical brackets so
that contact is avoided between the heat exchanger surfaces of the
fin and the tube of the condenser and radiator heat exchangers.
[0010] In summary, contemporary automotive radiators and condensers
are being combined by mechanical assembly and mounted in vehicles.
Fabrication and manufacturing costs are significant.
SUMMARY OF THE INVENTION
[0011] In light of such prior art approaches, it would be desirable
to manufacture in a single assembly that which was previously
available only as two or more assemblies. More specifically, it
would be desirable to produce a multi purpose exchanger of thermal
energy (e.g. a condenser/radiator combination) by brazing the
assembly as a single unit which by design would allow for
independent functionality of the radiator and condenser
systems.
[0012] Accordingly, the disclosed invention calls for a fin that
includes a radiator fin and a condenser fin (in the case of a
condenser/radiator assembly) that are separated by a thermal break.
In order for the thermal break to be effective, it is integrated
with other components of the heat exchanger assembly: headers, side
supports, and channels or flattened tubes.
[0013] The cores of the disclosed invention have one or more fins
interposed between the channels and the manifolds. The fins are
separated from each other by a thermal barrier comprising a slit
which is formed without removal of material. The slit inhibits the
flow of heat energy across the width of the strip. At least some of
the fins include louvers defined within the strip of which the fins
are constructed. The louvers extend transversely partially across a
given elongated strip. The louvers are configured in a plurality of
arrays, the arrays being situated adjacent each other across the
elongated strip.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1(a) is a perspective view of an exchanger of thermal
energy through which a cooling medium (such as ambient air)
passes;
[0015] FIG. 1(b) is a sectional view in the plane 1b-1b of FIG.
1(a), illustrating a multiple core heat exchanger made according to
the present invention;
[0016] FIG. 1(c) is a top plan view of a flattened fin which
illustrates a thermal break between adjacent fins and bridges of
material continuity (thermal fuses) extending between adjacent
edges of the fins;
[0017] FIG. 1(d) is a quartering perspective view of a serpentine
form of fin made according to the present invention;
[0018] FIGS. 2(a)-(f) are more detailed sections of a fin of the
subject invention;
[0019] FIG. 3 illustrates the locations of thermal fuses in the fin
of the subject invention;
[0020] FIG. 4 is an assembly drawing of a fin roll which, in one
alternative method, is used to manufacture the fin of the present
invention;
[0021] FIG. 5 is a sectional view taken along the line 5-5 in FIG.
4;
[0022] FIGS. 6(a)-(e) are side elevational views of cutting blades
that are assembled into a fin-forming roll that illustrate the
geometry which forms the louvered and non-louvered surfaces of the
serpentine fin;
[0023] FIGS. 7(a)-(c) depict blade tooth forms which when rolled in
the locations shown in FIG. 5, create slits along the length of the
fin, which form the thermal break in section 2e-2e (FIG. 2(a));
and
[0024] FIG. 8 illustrates alternative embodiments of the thermal
fuses of the subject invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] FIG. 1(a) illustrates one embodiment of the disclosed
exchanger of thermal energy: a heat exchanger 10 for a vehicle. The
exchanger of thermal energy has a core providing fluid passages
through which, for example, a coolant (such as water) flows through
a radiator while in cooling a water-cooled engine. A core portion
of a condenser 12 is illustrated in FIG. 1(b). It provides fluid
passages through which a refrigerant circulates in a refrigeration
cycle. Conventionally, the temperature of the refrigerant is lower
than that of the coolant. Accordingly, the core portion of the
condenser is typically oriented on the air upstream side of the
core portion of the radiator.
[0026] FIG. 1(a) depicts a exchanger of thermal energy 10 (such as,
but not limited to a condenser) through which a cooling medium such
as air passes. The heat exchanger 10 includes such features as
channels or flattened tubes 14 that extend transversely between
spatially separated manifolds or headers. Fins 16 (preferably, but
not necessarily in convoluted or serpentine form) are inserted
between and fused to the fluid-carrying transverse channels 14 to
facilitate the heat exchange between a fluid flowing in the
channels and the cooling medium, such as ambient air. Once
assembled, the manifolds, the channels, and fins are fused to each
other to form an integral, fluid-tight assembly. The exchanger of
thermal energy 10 may be used as a radiator, oil cooler,
transmission cooler, charge air cooler, condenser, evaporator,
heater or any other type of heat exchange assembly.
[0027] FIG. 1(b) is a cross-sectional view taken along the line
1b-1b of FIG. 1(a). A first core 12 is, for example, a condenser
that is placed on the upwind side of the multiple core exchanger of
thermal energy 10. A second exchanger of thermal energy 30 (such
as, but not limited to a radiator) is juxtaposed therewith. Both
cores 12, 24 are disposed between the side manifolds shown in FIG.
1(a).
[0028] The first core 12 has a plurality of first channels 14
through which a first fluid flows and a first fin 16 that is
disposed, preferably in a convoluted manner, between adjacent first
channels 14 to facilitate heat exchange between the first fluid and
the cooling medium.
[0029] On the right hand side of FIG. 1(b), a second core 30 (such
as a radiator) is disposed downstream of the first core 12. The
second core 30 has a plurality of second channels 32 through which
a second fluid flows. A second fin 34 is disposed between adjacent
second channels 32 to facilitate heat exchange between the second
fluid and the cooling medium. The second channels 32 extend
substantially parallel with the first channels 14.
[0030] Turning now to FIGS. 1(c)-(d), there are depicted top and
quartering views of a flattened strip of pre-corrugated material
that has been flattened for visualization (FIG. 1 (c)) and after it
is corrugated into a serpentine fin configuration (FIG. 1(d)). As
best seen in FIG. 1(d), the first fin 16 has first upper folds 18,
first lower folds 20 and first walls 22 extending between one of
the first upper folds and one of the first lower folds. Optionally,
a first array of louvers 24 extends from the first wall 22.
[0031] The second fin 34 (FIG. 1(d)) is integrally formed with the
first fin 16. Thus, the second fin 34 also has a corrugated shape
defined by second upper folds 36, second lower folds 38 and second
walls 40 that connect one of the second upper folds 36 and one of
the second lower folds 38. Optionally, a second array of louvers 42
extends from the second wall 40.
[0032] A thermal break comprising a slit 50 (FIGS. 1(c)-(d)) is
formed without removal of material between the first and second
upper and lower folds, and the first and second walls. The slit 50
insulates heat conductivity between the first and second fins, and
may be of uniform or non-uniform length.
[0033] As best illustrated in FIG. 1(c), one or more thermal fuses
or bridges 52 locally connect the first and second fins.
Optionally, the thermal fuses 52 may or may not be broken after
brazing. Such a selective activation function permits the designer
to promote structural integrity during pre-braze assembly and
enable a localized transfer of heat. It will be appreciated that
such fusing can be fabricated from heavy-gauge or light-gauge
material so that they may respectively retain mechanical integrity
and positioning, or be readily degradable.
[0034] Continuing with reference primarily to FIG. 1(c), the first
and second fins 16, 34 comprise an elongated strip 60 having a pair
of opposing edges 62, 64, an upper 66 and a lower face 68 (FIG.
1(d)) and (optionally) at least one louver 70 defined within the
strip so that no material of which the strip is formed is removed
during formation of the at least one louver. As illustrated in
FIGS. 1(c)-1(d), the at least one louver extends transversely at
least partially across the elongated strip, either inclined or
orthogonally to its edges.
[0035] As best shown in FIG. 1(c) the thermal fuse 52 is formed
between adjacent edges 64 of the first and second fins 16, 34. Each
thermal fuse 52 comprises a portion of material continuity
extending between the first and second fins 16, 34 for promoting
stability during construction of the exchanger of thermal
energy.
[0036] Since it is undesirable to have the heat exchange surfaces
of the condenser and radiator in physical contact in one
embodiment, the thermal fuse can be eliminated following mechanical
assembly by subsequent degradation during the brazing process or by
other means, such as chemical dissolution by an active flux during
controlled atmosphere brazing. The consequent reduction in the
number of thermal fuses serves to further isolate the radiator and
condenser forms of exchangers of thermal energy. Thus, the thermal
fuse 52 fulfills the dual role of adding strength during assembly
while degrading fin junctions during operation.
[0037] Continuing with primary reference to FIG. 1(c), the first
fin has a width (L.sub.1), and the second fin has a width
(L.sub.2). Preferably, but not necessarily, L.sub.1 is less than or
equal to L.sub.2 where the first and second heat exchangers are
respectively a condenser and a radiator.
[0038] Turning now to FIGS. 2(a)-(f), there are depicted other
views of the thermal break comprising a slit 50 and a thermal fuse
52 (FIG. 2(e)) between condenser and radiator fins. In FIG. 2(b),
the slit 50 is shown with displaced opposing edges, thereby
creating one form of the thermal break. In the example shown in
FIG. 3, the thermal fuse appears once every 6.5 convolutions. FIGS.
2(c)-(f) are sectional views taken along the respective sectional
lines illustrated in FIG. 2(a). FIG. 2(c) illustrates a
configuration wherein the first fin 16 has one array of louvers
extending between the edges thereof. FIG. 2(e) illustrates a
configuration wherein the louver (in the example shown, of the
second core 34) are split. FIG. 2(e) illustrates fin separation and
the slit 50 formed between the first and second upper and lower
folds, and the first and second walls. For comparison, FIG. 2(f)
illustrates a neutral surface of either fin.
[0039] Turning now to FIG. 3, there is depicted a side elevational
view of a fin which is illustrative of that which may be associated
with either the first or the second cores 12, 30. It should be
understood that the thermal fuse 52 can be located on the upper
folds 18, 36 respectively of the first or second fins 16, 34, or
the lower folds 20, 38. In one embodiment, the thermal fuses 52 are
located once every 6 and one-half convolutions. As illustrated, the
thermal fuse 52 is located alternatively from top to bottom, but
need not be so located.
[0040] The slits 50 and thermal fuses 52 can be manufactured by
such techniques as laser cutting, plasma cutting, water jet
cutting, or other similar processes. Preferably, to form the fin
depicted in FIG. 3, a fin forming roll produces 4 such thermal
fuses during each revolution of the fin roll. The minimum number
possible is one thermal fuse per revolution of the fin roll, which
could exist either on the top of the fin or the bottom of the fin.
The number of thermal fuses cannot exceed the number of teeth on
the fin roll. Equal spacing between the thermal fuses is not a
requirement. Irregular spacing is enabled by using such techniques
as laser cutting, plasma cutting, or water jet cutting.
[0041] Turning now to FIG. 4, there is depicted an assembly drawing
of a fin roll which creates a fin with a plurality of thermal
fuses. The reference numerals 12, 30, and 50 respectively indicate
the locations on the fin roll that form the first and second fins
16, 34 and the thermal break 50.
[0042] FIG. 5, is a sectional view taken along the line 5-5 of FIG.
4, illustrates the locations of each blade in the fin roll which
create a specific part feature, e.g. louvered and non-louvered
areas. The thermal break is created at fin blade locations)
locations 80, 82. The blades on the left hand side of FIG. 5 form
the first core (e.g. condenser). The blades on the right hand side
of FIG. 5 form the second core (e.g. radiator).
[0043] FIGS. 6(a)-(e), illustrate the shapes of teeth in a fin roll
that form the louvered and non-louvered surfaces of the fin. An
appreciation of the surfaces and shapes is helpful in visualizing
the different louver patterns formed by the blades depicted in
FIGS. 4-5. FIG. 6(a) depicts a blade which is used to form a border
90 (FIG. 5). FIG. 6(b) shows the blade form used in sections 94, 96
of the fin roll (FIG. 5). FIG. 6(c) illustrates the form of blade
which is used at 98, 100 of the fin roll illustrated in FIG. 5.
FIG. 6(d) illustrates a cutting blade on which the shapes of the
teeth create different louver patterns. FIG. 6(e) illustrates the
blade form that occupies positions 102, 104 of the fin roll in FIG.
5.
[0044] FIGS. 7(a)-(c), respectively illustrate the crotch areas of
blades used in the fin forming roll. The normal crotch areas are
depicted by the reference numeral 110 in FIG. 7(a). The altered
crotch 112 creates two locations at which there is a thermal fuse
52 at location 80. FIG. 7(b) illustrates a blade configuration at
locations 82 (FIG. 5). In FIG. 7(b), the exaggerated tooth form 114
is at location 82 (FIG. 5). In FIG. 7(c), the special crotches 112
(FIG. 7(a) are shown in relation to the overall circumference of
the fin roll at locations 116.
[0045] Thus, FIGS. 7(a)-(b) illustrate the blade forms which when
rolled in the proper locations defined in FIG. 5 create a
continuous slit 50 along the length of the blade edge form. The
slit continues to be formed until a specially designed area of the
form is encountered in the shape of an altered crotch 112 (FIG.
7(a)). This area is designed to allow the radiator side of the fin,
for example, to be joined with the condenser side of the fin. It
should be realized that the altered area to create a thermal fuse
need not reside at the crest of a convolution or bend radius. It
can exist anywhere on the flank of a tooth.
[0046] Preferably, the thermal fuse 52 is located on a wall of a
fin, approximately midway between two adjacent bend radii. Such a
configuration orients the thermal break in the midair wall of the
core. Thus, using the disclosed fin roll, the location of the
thermal fuse is predicted, as opposed to being randomly placed by
an additional operation.
[0047] As mentioned above, the thermal fuse 52 eliminates or
reduces the number of thermal junctions, so that heat transfer
characteristics in the combined exchanger of thermal energy are
improved. To improve the isolation between the radiator and
condenser, the thermal fuse 52 provides mechanical support during
assembly and may optionally subsequently be degraded or eliminated
during the brazing process. The thermal fuse contemplates that the
morphology of the junctions may be small and can be removed by
chemical dissolution using an effective flux during controlled
atmosphere brazing and/or thermal degradation. This results in a
reduction in the number of thermal junctions and serves to further
isolate the cores in the exchanger of thermal energy.
[0048] FIG. 8 illustrates an enlargement of the area in FIG. 1(c)
depicted by the reference numeral 52 and shows alternative thermal
fuse morphology. In FIG. 8(a), the thermal fuse is generally
rectangular or square with sides depicted as X and Y. In FIG. 8(a),
preferably, the length of segment X (where X.gtoreq.zero at the
thermal break) is less than or equal to that of segment Y. In FIG.
8(b) the thermal fuse is formed by two curvilinear arcuate
sections. In both FIGS. 8(a) and 8(b), the thermal fuse is made of
a homogeneous material. In FIG. 8(c), the thermal fuse includes
cavities or areas of material discontinuity. It will be appreciated
that any combination of these configurations may be effective in
use.
[0049] While embodiments of the invention have been illustrated and
described, it is not intended that these embodiments illustrate and
describe all possible forms of the invention. Rather, the words
used in the specification are words of description rather than
limitation, and it is understood that various changes may be made
without departing from the spirit and scope of the invention.
* * * * *