U.S. patent application number 16/558762 was filed with the patent office on 2021-03-04 for curved heat exchanger and method of manufacturing.
This patent application is currently assigned to MAHLE International GmbH. The applicant listed for this patent is MAHLE International GmbH. Invention is credited to Scott Kent, John Rosen.
Application Number | 20210063089 16/558762 |
Document ID | / |
Family ID | 1000004331456 |
Filed Date | 2021-03-04 |
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United States Patent
Application |
20210063089 |
Kind Code |
A1 |
Rosen; John ; et
al. |
March 4, 2021 |
CURVED HEAT EXCHANGER AND METHOD OF MANUFACTURING
Abstract
A heat exchanger has an upper manifold with a first curved
section; a lower manifold spaced from and extending parallel to the
upper manifold and having a second curved section; a plurality of
refrigerant tubes, and a plurality of corrugated fins. Each
corrugated fin is formed by a strip having radiused portions
alternating with planar portions, and the radiused portions are in
contact with the respective adjacent refrigerant tubes. Each of the
fins has a curve-inner edge and a curve outer edge and at least one
edge of the curve-inner edge and the curve outer edge of at least
one fin has a recessed portion in the planar portions that is
recessed inward toward a center of the core.
Inventors: |
Rosen; John; (Williamsville,
NY) ; Kent; Scott; (Albion, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MAHLE International GmbH |
Stuttgart |
|
DE |
|
|
Assignee: |
MAHLE International GmbH
|
Family ID: |
1000004331456 |
Appl. No.: |
16/558762 |
Filed: |
September 3, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F28F 2275/12 20130101;
F28D 2001/0273 20130101; F28F 1/126 20130101; F28D 1/05383
20130101 |
International
Class: |
F28D 1/053 20060101
F28D001/053; F28F 1/12 20060101 F28F001/12 |
Claims
1. A heat exchanger comprising: an upper manifold having a first
curved section; a lower manifold spaced from and extending parallel
to the upper manifold and having a second curved section; a
plurality of refrigerant tubes, each refrigerant tube of the
plurality of refrigerant tubes extending along a tube length from
the upper manifold to the lower manifold and in hydraulic
communication with the upper and lower manifolds; a plurality of
corrugated fins, each of the corrugated fins inserted between
respective adjacent ones of the refrigerant tubes, the refrigerant
tubes and corrugated fins defining a core having a plurality of air
channels from a curve-outer face of the core to a curve-inner face
of the core, each corrugated fin of the plurality of corrugated
fins being formed by a strip having radiused portions alternating
with planar portions, wherein the radiused portions are in contact
with the respective adjacent refrigerant tubes, wherein each of the
fins has a curve-inner edge and a curve outer edge and at least one
edge of the curve-inner edge and the curve outer edge of at least
one fin extending between the first curved section and the second
curved section has a recessed portion in the planar portions that
is recessed inward toward a center of the core.
2. The heat exchanger according to claim 1, wherein the recessed
portion in the planar portions is bent toward the lower
manifold.
3. The heat exchanger according to claim 1, wherein the recessed
portion is a central subsection of the planar portions between two
subsections of the planar portion, where the edge extends as far
outward from the core as the edge of the radiused portions.
4. The heat exchanger according to claim 1, wherein the recessed
portion is recessed by a depth within a range of 2% to 50% of a
local heater core depth.
5. The heat exchanger according to claim 1, wherein the recessed
portion is present in each of the planar portions of the fin at
least on the curve-inner edge or on the curve outer edge.
6. The heat exchanger according to claim 1, wherein the recessed
portion is present on both the curve-inner edge and the curve outer
edge.
7. The heat exchanger according to claim 1, wherein at least two of
the fins have a recessed edge, wherein the at least two of the fins
are spaced apart by at least one intermediate fin lacking a
recessed portion on a side where the at least two of the fins
adjacent to the intermediate fin have a recessed portion.
8. The heat exchanger according to claim 1, wherein the recessed
portion is on the curve-inner edge, wherein a subsection of the
curve-inner edge is folded down to extend downward toward the lower
manifold.
9. The heat exchanger according to claim 1, wherein the recessed
portion comprises an incision formed in the at least one edge, the
incision extending inward toward the center of the core.
10. The heat exchanger according to claim 8, wherein the edge is
bent downward toward the lower manifold in regions laterally
adjoining the incision.
11. The heat exchanger according to claim 1, wherein the recessed
portion is disposed on both the curve-inner edge and the
curve-outer edge, wherein a subsection of the curve-inner edge is
folded down to extend downward toward the lower manifold and
wherein an incision is formed in the curve-outer edge, the incision
extending inward toward the center of the core.
12. The heat exchanger according to claim 1, wherein the recessed
portion is disposed on both the curve-inner edge and the
curve-outer edge, wherein an incision is formed in both the
curve-inner edge and the curve-outer edge, the incision extending
inward toward the center of the core.
13. A method of making a curved heat exchanger, the method
comprising the following steps: assembling parts of the heat
exchanger, the parts, after assembly, form a flat heat exchanger
including: an upper manifold having a straight elongated shape; an
lower manifold spaced from and extending parallel to the upper
manifold; a plurality of refrigerant tubes, each refrigerant tube
of the plurality of refrigerant tubes extending along a tube length
with one tube end attached to the upper manifold and another tube
end attached to the lower manifold; and a plurality of corrugated
fins, each of the corrugated fins inserted between two respective
adjacent ones of the refrigerant tubes, the refrigerant tubes and
corrugated fins defining a core having a plurality of air channels
for airflow from a first face of the core to a second face of the
core, each corrugated fin of the plurality of corrugated fins being
formed by a strip having radiused portions alternating with planar
portions, wherein the radiused portions are in contact with the
respective adjacent refrigerant tubes; driving an edge tool along
the first face of the core between the respective adjacent
refrigerant tubes in a direction parallel to the refrigerant tubes
so as to form a respective recessed portion in a plurality of the
planar portions; and bending the first manifold, the second
manifold, and the core about a common bending axis extending
parallel to the refrigerant tubes to form a curved portion of the
heat exchanger, wherein the curved portion of the heat exchanger
includes the recessed portions.
14. The method according to claim 13, wherein the step of driving
the edge tool along the first face also bends the fin downward
toward the lower manifold.
15. The method according to claim 13, comprising the further step
of driving the edge tool along the first face of the core between
additional two adjacent refrigerant tubes so as to form a
respective recessed portion in a plurality of the planar portions
of a different one of the plurality of corrugated fins.
16. The method according to claim 13, wherein the first face
including the recessed portions is a curve-inner face of the
core.
17. The method according to claim 13, wherein the first face
including the recessed portions is a curve-outer face of the
core.
18. The method according to claim 13, comprising the further step
of driving the edge tool or a different edge tool along the second
face of the core between the respective adjacent refrigerant tubes
or between different adjacent refrigerant tubes in a direction
parallel to the refrigerant tubes so as to form further respective
recessed portions in a plurality of the planar portions.
19. The method according to claim 13, wherein the edge tool is a
folding tool and the recessed portions are formed by folded-down
edge portions.
20. The method according to claim 13, wherein the edge tool is a
scoring tool and the recessed portions are formed by cut edge
portions.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to a curved heat exchanger
with two bent manifolds connected by a heat exchanger core that
includes refrigerant tubes and fins.
BACKGROUND
[0002] Heat exchangers have various uses in the automotive
industry. Some applications require a bent shape heat exchanger.
For heat exchangers featuring flat micro-channel refrigerant tubes
separated by corrugated fins, the bending process is challenging.
Bending micro-channel heat exchanger cores (MCHX cores) by bending
the manifolds causes full width fin centers to crush in various
locations, and the center crush varies uncontrollably between
different fins along the length of the refrigerant tubes within the
bend zone portion of the core. This leads to bent tubes due to
irregular deformation of the fins.
SUMMARY
[0003] According to the present disclosure, a heat exchanger has an
upper manifold having a first curved section; a lower manifold
spaced from and extending parallel to the upper manifold and having
a second curved section; a plurality of refrigerant tubes, and a
plurality of corrugated fins. Each refrigerant tube extends along a
tube length from the upper manifold to the lower manifold and is in
hydraulic communication with the upper and lower manifolds. Each of
the corrugated fins is inserted between respective adjacent ones of
the refrigerant tubes so that the refrigerant tubes and corrugated
fins define a core having a plurality of air channels from a
curve-outer face of the core to a curve-inner face of the core.
Each corrugated fin is formed by a strip having radiused portions
alternating with planar portions, and the radiused portions are in
contact with the respective adjacent refrigerant tubes. Each of the
fins has a curve-inner edge and a curve outer edge and at least one
edge of the curve-inner edge and the curve outer edge of at least
one fin has a recessed portion in the planar portions that is
recessed inward toward a center of the core.
[0004] According to one aspect of the present disclosure, the
recessed portion in the planar portions is bent toward the lower
manifold.
[0005] Accordingly, the recessed portion may be a central
subsection of the planar portions between two subsections of the
planar portion, where the edge extends as far outward from the core
as the edge of the radiused portions.
[0006] The recessed portion may be recessed by a depth within a
range of 2% and 50% of a total core depth.
[0007] The recessed portion may be present in each of the planar
portions of the respective fin at least on the curve-inner edge or
on the curve outer edge.
[0008] The recessed portion may alternatively be present on both
the curve-inner edge and the curve outer edge.
[0009] Two of the fins that have a recessed edge may be spaced
apart by at least one intermediate fin lacking a recessed portion
on the side where two adjacent fins have a recessed portion.
[0010] In heat exchangers, in which the recessed portion is on the
curve-inner edge, a subsection of the curve-inner edge may be
folded down to extend downward toward the lower manifold.
[0011] Alternatively, the recessed portion may have an incision
formed in the at least one edge, the incision extending inward
toward the center of the core. In this case, the recessed portion
may be on the curve-inner edge, the curve-outer edge, or both.
[0012] The cut edge may additionally be bent downward toward the
lower manifold in regions laterally adjoining the incision.
[0013] In heat exchangers, in which the recessed portion is
disposed on both the curve-inner edge and the curve-outer edge of a
fin, a subsection of the curve-inner edge may be folded down to
extend downward toward the lower manifold and an incision may be
formed in the curve-outer edge.
[0014] According to a further aspect of the present disclosure, a
method of making a curved heat exchanger comprises the following
steps:
[0015] assembling parts of the heat exchanger, the parts, after
assembly, form a flat heat exchanger including:
[0016] an upper manifold having a straight elongated shape;
[0017] an lower manifold spaced from and extending parallel to the
upper manifold;
[0018] a plurality of refrigerant tubes, each refrigerant tube of
the plurality of refrigerant tubes extending along a tube length
with one tube end attached to the upper manifold and another tube
end attached to the lower manifold; and
[0019] a plurality of corrugated fins, each of the corrugated fins
inserted between two respective adjacent ones of the refrigerant
tubes, the refrigerant tubes and corrugated fins defining a core
having a plurality of air channels for airflow from a first face of
the core to a second face of the core, each corrugated fin of the
plurality of corrugated fins being formed by a strip having
radiused portions alternating with planar portions, wherein the
radiused portions are in contact with the respective adjacent
refrigerant tubes;
[0020] driving an edge tool along the first face of the core
between the respective adjacent refrigerant tubes in a direction
parallel to the refrigerant tubes so as to form a respective
recessed portion in a plurality of the planar portions; and
[0021] bending the first manifold, the second manifold, and the
core about a common bending axis extending parallel to the
refrigerant tubes to form a curved portion of the heat exchanger,
wherein the curved portion of the heat exchanger includes the
recessed portions.
[0022] The step of driving the edge tool along the first face may
also bend the fin downward toward the lower manifold.
[0023] This step of driving the edge tool may be repeated on a
different one of the plurality of corrugated fins.
[0024] The first face including the recessed portions may be a
curve-inner face of the core or a curve-outer face of the core.
[0025] The step of driving the edge tool or a different edge tool
may be repeated along the second face of the core between the
respective adjacent refrigerant tubes or between different adjacent
refrigerant tubes in a direction parallel to the refrigerant tubes
so as to form further respective recessed portions in a plurality
of the planar portions.
[0026] In one version, the edge tool is a folding tool and the
recessed portions are formed by folded-down edge portions.
[0027] In a different version, the edge tool is a scoring tool and
the recessed portions are formed by cut edge portions.
[0028] Further details and benefits of the present disclosure will
become apparent from the following description of the appended
drawings. The drawings are provided herewith solely for
illustrative purposes and are not intended to limit the scope of
the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] In the drawings,
[0030] FIG. 1 shows a heat exchanger prior to bending into a curved
heat exchanger;
[0031] FIG. 2 shows a first edge tool in the form of a folding
tool;
[0032] FIG. 3 shows a heat exchanger in the process of folding down
edges of corrugated fins;
[0033] FIG. 4A shows a detail view of a fin prior to applying the
folding tool;
[0034] FIG. 4B shows a detail view of a fin after applying the
folding tool;
[0035] FIG. 4C shows a detail view of the fin of FIG. 4B in a
perspective indicated by line C-C of FIG. 4B;
[0036] FIG. 5 shows a heat exchanger with folded fin edges after
bending the heat exchanger into a curved heat exchanger;
[0037] FIG. 6 shows a second edge tool in the form of a scoring
tool;
[0038] FIG. 7 shows a heat exchanger in the process of cutting
edges of corrugated fins;
[0039] FIG. 8A shows a detail view of a fin prior to applying the
scoring tool;
[0040] FIG. 8B shows a detail view of a fin after applying the
scoring tool;
[0041] FIG. 8C shows a detail view of the fin of FIG. 8B in a
perspective indicated by line C-C of FIG. 8B;
[0042] FIG. 9 shows a curve-inner side of a heat exchanger with cut
fin edges after bending the heat exchanger into a curved heat
exchanger;
[0043] FIG. 10 shows a curve-outer side of the heat exchanger of
FIG. 5 or of a different heat exchanger with cut fin edges after
bending the heat exchanger into a curved heat exchanger;
[0044] FIG. 11 shows a cross-sectional detail view of a heat
exchanger with both cut and folded fin edges;
[0045] FIG. 12 shows a schematic cross-sectional detail view of a
heat exchanger with a full core; and
[0046] FIG. 13 shows a schematic cross-sectional detail view of a
heat exchanger with a recessed core.
DETAILED DESCRIPTION OF THE DRAWINGS
[0047] FIG. 1 shows an example of a heat exchanger 10 that, prior
to bending, has a horizontal lower straight manifold and a
horizontal upper straight manifold, which are spaced apart from
each other extend parallel to each other. A plurality of parallel
equidistant refrigerant tubes 14 extend from the lower manifold 12
to the upper manifold 13. Each of the refrigerant tubes 14 is in
hydraulic communication with the upper and lower manifolds 12 and
13. The lower manifold 12 and the upper manifold 13 are of
cylindrical tubular shape, while the refrigerant tubes 14 are flat
tubes. Each of the refrigerant tubes 14 may be internally divided
into a plurality of microchannels. The flat sides of adjacent flat
tubes face each other.
[0048] A plurality of corrugated fins are arranged between the
refrigerant tubes 14. Each of the corrugated fins spans the
distance between respective adjacent ones of the refrigerant tubes
14 so that the refrigerant tubes 14 and corrugated fins form a core
of the heat exchanger 10. The corrugation of the fins defines a
plurality of air channels from an upstream face of the core to a
downstream face of the core. Each corrugated fin 16 of the
plurality of corrugated fins is formed by a strip having radiused
portions alternating with planar portions 19 as is, for example,
shown in FIGS. 4A and 8A. The radiused portions are in contact with
the respective adjacent refrigerant tubes 14. FIGS. 4A and 8A also
show micro-louvers 17 that may be formed from the strip material of
the fin 16 and that are also present in FIG. 11.
[0049] When a heat exchanger 10 of the type shown in FIG. 1 is bent
about a bend axis that extends parallel to the refrigerant tubes
14, the curve-inner side 38 of the core is laterally compressed,
while the curve-outer side 40 of the core is expanded, as will be
further discussed below in regards to FIG. 5. As the lower manifold
12 and the upper manifold 13 are bent parallel to each other,
forces acting on the core may cause irregular deformation of the
refrigerant tubes 14 and of the fins that impairs the optical
appearance and may locally reduce the cross-sections of
microchannels in some of the refrigerant tubes 14.
[0050] According to one aspect of the present disclosure, FIGS. 2
and 3 show a process of pre-treating the curve-inner side 38 of a
heat exchanger 10 of the type shown in FIG. 1 for facilitating a
uniform deformation across the curve inner side of the heat
exchanger 10 without the need for protective inserts or complex
tools. FIG. 2 shows a simple manual edge tool for creating a
deformation of the edges of the fins on the curve-inner side 38.
The edge tool of FIG. 2 includes a handle 20, a cylindrical shaft
22, and a conical tip 24. The edge tool forms a folding tool 18
that is run along the curve-inner edges 42 of at least some of the
fins in the direction of the refrigerant tubes 14 between two
adjacent refrigerant tubes 14. In view of the later use of the heat
exchanger 10 that may result in condensed water collecting on the
heat exchanger 10 core, it is preferred that the folding tool 18 is
run along the fin edges from the upper manifold 13 toward the lower
manifold 12 to facilitate the run-off of condensate. In the example
shown in FIG. 3, the folding tool 18 is applied to fold down the
edges of every other fin 16 arranged within a core section that
will be bent in a later step.
[0051] The folding tool 18 is preferably held at an angle where the
fin 16 is contacted by the blunt annular edge of the transition
between the cylindrical shaft 22 and the conical tip 24. The tip 24
of the folding tool 18 may alternatively be a rounded blunt tip
24.
[0052] FIG. 4B shows a close-up detail of the folded edge of a fin
16 treated with the folding tool 18. In comparison with FIG. 4A,
which shows the untreated fin edges, the edge portions 26 at
centers of the planar portions 19 of the fin 16 are all folded down
toward the lower manifold 12. The width of the folded edge portions
26 of the fin 16 depends on the diameter of the folding tool 18
used to deform the edge. Preferably, however, the folded edge
portions 26 form a central subsection of the planar portions 19,
are limited to only the planar portions 19, and do not extend to
the radiused portions of the fin 16.
[0053] FIG. 4C shows one of the folded-down edge portions of the
fin 16 from below as indicated by the line C-C in FIG. 4B. By
folding the edge of the fin 16 downward toward the lower manifold
12, the edge is recessed inward toward the center of the core in
the folded edge portion 26 relative to an unfolded edge portion 27.
The recess depth d of the folded edge portion 26 relative to the
unfolded edge portion 27 provides a weakened resistance to bending
and thereby a predetermined collapse point when the lower manifold
12, the upper manifold 13, and the core are bent to a desired
curvature. The recess depth d of the folded edge portions 26 may be
within the range of 2% to 30% of the depth of the heat exchanger
core, preferably 4% to 20%, for example within the range of 1 mm to
5 mm for a heat exchanger core having a depth of 2.5 cm (1
inch).
[0054] As will be described in more detail below, it has been found
that alternating fins having folded edge portions 26 with fins
having unfolded edge portions 27 is sufficient to protect the
straight configuration of the refrigerant tubes 14 during bending
because each refrigerant tube 14 is adjacent to a fin 16 with
folded edge portions 26 on one side of the refrigerant tube 14 that
provides the predetermined collapse points. It would, however, be
within the scope of the present invention if adjacent fins had
folded edge portions 26 within the curved section 46 of the heat
exchanger 10, or if only every third or fourth fin had folded edge
portions, depending on the desired curvature radius of the heat
exchanger. A greater curvature radius would require fewer fins with
recessed edge portions.
[0055] FIG. 5 shows a heat exchanger 10 prepared as discussed above
with folded fin edges after bending the upper manifold 13, the
lower manifold 12, and the core about a bend axis A into a
specified curvature. The bend axis A extends parallel to the
refrigerant tubes 14. Because each refrigerant tube 14 within the
curved section 46 of the heat exchanger 10 is adjoined by a fin 16
with folded edge portions 26, the refrigerant tubes 14 retain their
integrity during the bending process. Accordingly, the refrigerant
tubes 14 remain straight after bending. Instead, the folded fins
collapse in the locations of the folded edge portions 26 that
represent predetermined collapse points.
[0056] FIGS. 6 through 10 illustrate a variation of producing
recessed fin edges that is suitable for curve-inner edges 42 and
curve-outer edges 44 of the fins alike. FIG. 6 shows an edge tool
used for providing the recessed edge portions according to this
variation. The edge tool is a scoring tool 28 with a handle 30, and
a blade 32. The blade 32 has a convexly curved cutting edge 34.
[0057] The scoring tool 28 is run along the curve-inner edges 42 of
at least some of the fins in the direction of the refrigerant tubes
14 between two adjacent refrigerant tubes 14. By running the
scoring tool 28 along the fin edge as shown in FIG. 7, the fin
edges are provided with an incision 35 in a cut edge portion 36.
The cut edge portions 36 are located generally centrally in the
planar portions 19 of the fin 16. The planar portions 19
immediately adjoining the incision 35 may be pulled in the
direction of movement of the scoring tool 28. In view of the later
use of the heat exchanger 10 that may result in condensed water
collecting on the heat exchanger 10 core, it is thus preferred that
the scoring tool 28 is run along the fin edges from the upper
manifold 13 toward the lower manifold 12 to facilitate the run-off
of condensate. In the example shown in FIG. 7, the scoring tool 28
is applied to cut the edges of every other fin 16 arranged within a
core section that will be bent in a later step.
[0058] The scoring tool 28 is preferably held at an angle where the
fin 16 is contacted by the convexly curved cutting edge 34 of the
blade 32. The scoring tool 28 may alternatively have a rounded
blade 32 extending at a different angle relative to the handle, for
example generally perpendicular to the handle.
[0059] FIG. 8B shows a close-up detail of the cut edge portion 36
of a fin 16 treated with the scoring tool 28. In comparison with
FIG. 8A, which shows the untreated fin edges, the edge portions 36
at centers of the planar portions 19 of the fin 16 are all cut
inward and slightly bent downward toward the lower manifold 12. The
extent of the downward bend of the lateral sides of the incisions
35 depends on the blade 32 of the scoring tool 28 used to deform
the edge and on the stiffness of the fin 16 material. Preferably,
however, the cut edge portions 36 including the bent sides form a
central subsection of the planar portions 19, are limited to only
the planar portions 19, and do not extend to the radiused portions
of the fin 16.
[0060] FIG. 8C shows one of the cut edge portions 36 of the fin 16
from below as indicated by the line C-C in FIG. 8B. By cutting the
edge of the fin 16, the edge is recessed inward toward the center
of the core in the cut edge portion 36 relative to an uncut edge
portion 37. The recess D of the cut edge portion 36 relative to the
uncut edge portion 37 provides a weakened resistance to bending or
tearing and thereby a predetermined collapse point or tear line
when the lower manifold 12, the upper manifold 13, and the core are
bent to a desired curvature. The recess depth D of the cut edge
portions 36 may be within the range of 5% to 50% of the depth of
the core, preferably within the range of 10% to 30%.
[0061] As the recesses in the fin edges are formed by incisions 35,
not just folds, these edges can be collapsed on the curve-inner
side 38 of or expanded on the curve-outer side 40 of a curved heat
exchanger 10. It has been found that alternating fins having cut
edges with fins having uncut edges 37 is sufficient to protect the
straight configuration of the refrigerant tubes 14 during bending
because each refrigerant tube 14 is adjacent to a fin 16 with cut
edge portions 36 on one side of the refrigerant tube 14 that
provides the predetermined collapse points or tear lines. It would,
however, be within the scope of the present invention if adjacent
fins had cut edge portions 36 within the curved section 46 of the
heat exchanger 10, or if only every third or fourth fin had cut
edge portions, depending on the desired curvature radius of the
heat exchanger. A greater curvature radius would require fewer fins
with recessed edge portions.
[0062] FIG. 9 shows a heat exchanger 10 prepared as discussed above
with cut fin edges after bending the upper manifold 13, the lower
manifold 12, and the core about a bend axis A into a specified
curvature such that the cut fin edges are on the curve-inner side
38 of the curved heat exchanger 10. The bend axis A extends
parallel to the refrigerant tubes 14. Because each refrigerant tube
14 within the curved section 46 of the heat exchanger 10 is
adjoined by a fin 16 with cut edge portions 36, the refrigerant
tubes 14 retain their integrity during the bending process.
Accordingly, the refrigerant tubes 14 remain straight after
bending. Instead, the cut fins collapse in the locations of the cut
edge portions 36 that represent predetermined collapse points.
[0063] FIG. 10 shows another heat exchanger 10 prepared as
discussed above with cut fin edges after bending the upper manifold
13, the lower manifold 12, and the core about a bend axis A into a
specified curvature such that the cut fin edges are on the
curve-outer side 40 of the curved heat exchanger 10. The bend axis
A again extends parallel to the refrigerant tubes 14. Because each
refrigerant tube 14 within the curved section 46 of the heat
exchanger 10 is adjoined by a fin 16 with cut edge portions 36, the
refrigerant tubes 14 retain their integrity during the bending
process. Accordingly, the refrigerant tubes 14 remain straight
after bending. Instead, the cut fins spread apart in the locations
of the cut edge portions 36 that represent predetermined tear
lines.
[0064] The principles of FIGS. 9 and 10, or of FIGS. 3 and 10,
while shown on different heat exchanger 10s, may be combined on a
single heat exchanger 10. For example, both the curve-inner and the
curve-outer fin edges may carry incisions 35, thus combining the
features of FIG. 9 and FIG. 10. Where only every other fin edge is
cut on a given side of the heat exchanger 10, the incisions 35 on
the curve-outer side 40 may be made in fins that also carry
incisions 35 on the curve-inner side 38. Alternatively, each of the
fins within the curved portion of the heat exchanger 10 may have a
cut edge, alternating between the curve-inner edge 42 and the curve
outer edge of adjacent fins.
[0065] Also, as discussed above, while the curve outer side of the
heat exchanger 10 may have cut fin edges, the curve-inner side 38
of the heat exchanger 10 may have folded fin edges. Again, where
only every other fin edge is cut on the curve-outer side 40 and
folded on the curve-inner side 38 of the heat exchanger 10, the
incisions 35 on the curve-outer side 40 may be made in fins that
also carry folds on the curve-inner side 38.
[0066] This is illustrated in FIG. 11, showing a vertical
cross-sectional cut through one of the corrugated fins. The
curve-inner side 38 of the fin 16 features folded edge portions 26,
while the curve-outer side 40 features cut edge portions 36.
Alternatively, each of the fins within the curved portion of the
heat exchanger 10 may have one of a cut edge and a folded edge,
alternating between the curve-inner edge 42 being folded and the
curve outer edge being cut from one fin 16 to the next.
[0067] Combining the principles of FIGS. 9 and 10, or of FIGS. 3
and 10 is of particular interest in heat exchanger 10s having a
full core as shown in FIG. 12, where the core composed of the
refrigerant tubes 14 and fins extends equally far to the
curve-inner side 38 and curve-outer side 40 of the manifold. Some
heat exchangers 10 are designed to have a recessed core as shown in
FIG. 13, at least in the curved section 46 of the heat exchanger
10. This recess may be on the curve-outer side 40 or the
curve-inner side 38, or on both sides 38 and 40. The entire curved
core section may be recessed on one side so that no cut edge
portions 36 or folded edge portions 26 may be necessary on that
side. If only one side of the curved core section is recessed
without any treated edge portions, the recessed side is preferably
the curve-outer side so that the cut edge portions 36 or folded
edge portions 26 are located on the curve-inner side, which is less
visible in the installed state of the heat exchanger. That way, the
curve-outer side has an optically more appealing appearance. The
recessed side of the core may be close enough to the central axis
of the manifold that the compression or expansion between the
refrigerant tubes 14 is sufficiently reduced to avoid deformations
of the refrigerant tubes 14. Alternatively, the even the fin edges
of a recessed core section may be folded or cut.
[0068] It should be noted that the step of folding or cutting the
fin edges in the planar portions has been described as a manual
process. This process, however, can easily be performed by a
machine providing a linear movement of a rake-like attachment, in
which each of the rake teeth is formed of an edge tool as
described. The edge tools may be interchangeable between a folding
tool and a cutting tool. Further, the lateral distances between the
rake teeth may be adjustable to account for different
requirements.
[0069] While the above description constitutes the preferred
embodiments of the present invention, it will be appreciated that
the invention is susceptible to modification, variation and change
without departing from the proper scope and fair meaning of the
accompanying claims.
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