U.S. patent application number 10/734526 was filed with the patent office on 2005-05-05 for folded tube for a heat exchanger and method of making same.
This patent application is currently assigned to Valeo Inc. Invention is credited to Bonnet, Pascal, Hu, Zaiqian, Smith, Didier.
Application Number | 20050092476 10/734526 |
Document ID | / |
Family ID | 34556165 |
Filed Date | 2005-05-05 |
United States Patent
Application |
20050092476 |
Kind Code |
A1 |
Hu, Zaiqian ; et
al. |
May 5, 2005 |
Folded tube for a heat exchanger and method of making same
Abstract
The present invention relates to a multi-port folded tube for a
heat exchanger, and, in particular, a multi-port condenser tube and
a method of making thereof. The present invention further comprises
a folded tube and method of making a multi-port folded tube for a
heat exchanger wherein at least one tube locking feature is
included.
Inventors: |
Hu, Zaiqian; (Carmel,
IN) ; Smith, Didier; (Columbus, IN) ; Bonnet,
Pascal; (Fishers, IN) |
Correspondence
Address: |
Valeo Inc
Intellectual Property Department
4100 North Atlantic Boulevard
Auburn Hills
MI
48326
US
|
Assignee: |
Valeo Inc
|
Family ID: |
34556165 |
Appl. No.: |
10/734526 |
Filed: |
December 12, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60516469 |
Oct 31, 2003 |
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Current U.S.
Class: |
165/177 |
Current CPC
Class: |
F28F 1/022 20130101;
F28D 1/0391 20130101 |
Class at
Publication: |
165/177 |
International
Class: |
F28F 001/00 |
Claims
What is claimed is:
1. A folded tube for a heat exchanger comprising: a base; a top
spaced from and opposing the base; a first side interposed between
the base and the top along one side thereof; a second side
interposed between the base and the top along another side thereof;
and each of the base and the top having at least one internal half
web; wherein the at least one top internal half web abuts the at
least one base internal half web to define a plurality of fluid
ports and wherein there is at least one tube locking feature.
2. A folded tube as set forth in claim 1 wherein the generally
planar sheet is shaped such that in forming the tube the width
across the tube is larger than the height of the tube.
3. A folded tube as set forth in claim 1 wherein the at least one
internal half web has a plurality of serrations to mix the fluid
flowing through the fluid ports.
4. A method of making a folded tube for a heat exchanger comprising
the steps of: providing a generally planar sheet; folding the sheet
and forming at least one top internal half web having a first fold
portion and a second fold portion and at least one base internal
half web having a first fold portion and a second fold portion;
folding the sheet and forming a base and a top opposing the base
and a first side interposed between the top and the base and a
second side interposed between the top and the base such that the
at least one top internal half web abuts the at least one base
internal half web to provide a plurality of fluid ports.
5. A method as set forth in claim 4 wherein the step of forming a
plurality of internal half webs further comprises the step of
providing a tube locking feature.
6. A method of making a folded tube as set forth in claim 5 wherein
the generally planar sheet is shaped such that in forming the tube
the width across the tube is larger than the height of the
tube.
7. A method as set forth in claim 6 wherein edges of the planar
sheet formed are flat edges and the tube locking feature is located
on the end of the tube.
8. A method as set forth in claim 7 wherein the flat edges being
formed close on the height side and have end edges being doubled
back against the wall to at least one material thickness in
length.
9. A folded tube as set forth in claim 1 wherein the at least one
tube locking feature is supported with a `T` shaped wall.
10. A folded tube as set forth in claim 1 wherein the at least one
tube locking feature is contained within a `U` shaped interior
wall.
11. A folded tube as set forth in claim 10 wherein the `U` shaped
interior wall is doubled.
12. A folded tube as set forth in claim 7 wherein the tube has
folded end edges forming perpendicular walls.
13. A folded tube as set forth in claim 11, wherein the tube has
folded end edges forming perpendicular walls.
14. A folded tube for a heat exchanger comprising: a base; a top
spaced from and opposing the base; a first side interposed between
the base and the top along one side thereof; a second side
interposed between the base and the top along another side thereof;
and each of the base and the top having at least one internal
oriented portion; wherein the at least one top internal oriented
portion abuts the at least one base internal oriented portion to
define a plurality of fluid ports and wherein there is least one
tube locking feature.
15. A folded tube as set forth in claim 14, wherein at least one
tube locking feature is at the tube end or other than the tube end.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to heat exchangers
for motor vehicles and, more specifically, to a folded tube and
method of making same for a heat exchanger, such as an condenser,
in a motor vehicle.
DESCRIPTION OF THE RELATED ART
[0002] It is known to provide a tube for a heat exchanger such as a
condenser in an air conditioning system of a motor vehicle. The
tube typically carries a first fluid medium in contact with its
interior while a second fluid medium contacts its exterior.
Typically, the first fluid medium is a liquid or a two-phase liquid
and gas mixture and the second fluid medium is a gas. Where a
temperature difference exists between the first and second fluid
mediums, heat will be transferred between the two via heat
conductive walls of the tube.
[0003] In addition, it is known to provide multi-port tubes for
condensers in an air conditioning system in a vehicle. Such tubes
often have small hydraulic diameter ports for heat transfer
enhancement. In addition, the interior port walls provide strength
to withstand the high-pressure requirements of the refrigerants in
such systems. A known method of forming a tube for a heat exchanger
is to extrude the tube in an extrusion process. Particularly with
multi-port type exchangers, the extruded tube has become the
`primary choice` for motor vehicle condensers when certain
performance levels are required. Extruded tubes of the multi-port
type have advantages such as being virtually leak-free and being a
structurally integrated part of the condenser. However, these sort
of extruded tubes have the disadvantages of requiring internal
dimensions that must have wide tolerances, in order to keep the
extrusion dies life span at a reasonable level to be practical,
i.e. tighter tolerances generally reduce die life, whereas the
requirement of wider tolerances of most extruded tubes of this
nature means that there is increased material usage, and, the
extruded tubes, therefore, are relatively expensive to produce.
[0004] Yet another known method of forming a tube for a heat
exchanger is to provide a flat, elongated sheet with lugs and the
ends of the sheet are folded to form the tube. The ends of the tube
are then brazed. An example of such a tube is disclosed in U.S.
Pat. No. 5,386,629 issued on Feb. 7, 1995, Ouchi et al. In this
patent, the tube may have flow paths between the lugs. However, the
quality of the folded tube to header joints is related to how small
the outside web shoulders can be with the smaller the better to
prevent leakage. U.S. Pat. No. 6,241,012 issued on Jun. 5, 2001, Yu
et al, disclosed a folded tube and method for making such for a
heat exchanger with a base and top and at least an internal web.
The folded tube has very small outside web shoulder radii and a
plurality of fluid parts.
[0005] U.S. Pat. 6,209,202 issued on Apr. 3, 2001, Rhodes et al,
discloses a folded tube and a method of making the same, including
a base, an opposing top, and sides interposed between including at
least one of the base and the top having at least one internal web.
Compression leads to multiple parts. Column 3, lines 35-40 and FIG.
4 show an arcuate shaped end feature.
[0006] One attempt to overcome the problems of the prior art
include designs for air condition applications wherein one end of
tube is `locked` by binding a number of layers of sheets of
material together to lock the tube. By binding, for example, 5
layers of sheet together, to lock the tube end, a very `strong` or
`solid` positive lock of the condenser tube is achieved prior to
brazing: however, such a layering and positive lock also imposes a
very rigid relationship between the total tube height, and sheet
gauge (tube wall thickness): the total tube height can be more than
about five times wall thickness in some cases.
[0007] As described above, attempts to overcome problems in
condenser brazing with flat tubes have often led to solutions that
impose very rigid relationships between total tube height and sheet
gauge. However, in those `solutions` several other problems have
been discovered: tube gauge might be not optimized since this rigid
relationship provides that once tube height is determined, tube
gauge is determined also, but not fully due to the structural
requirement; this relationship does not allow the use of potential
future stronger materials, since reducing the gauge to meet the
same structural requirement would not be possible due to the rigid
height gauge relationship; and the reduced flexibility in tube
design for different applications is less advantageous due to the
fact that heat exchanger tube design must consider both heat
transfer and airside pressure drop.
[0008] For exchangers with core depths greater than or equal to 25
millimeters, the higher air pressure drop involved with the
increased core depth, would mean it would be optimal to have lesser
tube height. On the other hand, for cores of short depth less than
or equal to 22 millimeters, because less airside pressure drop is
involved, tube height can be increased. The present invention
overcomes many of the problems described above.
OBJECTS OF THE INVENTION
[0009] It is an object of the present invention to provide a
multi-port folded tube for a heat exchanger, and, in particular, a
multi-port condenser tube and a method of making thereof. It is
further object of the present invention to provide a folded tube
and method of making a multi-port folded tube for a heat exchanger
wherein at least one tube locking feature is included.
[0010] It is a further object of the present invention to provide a
folded tube formed into multi-port tube wherein tighter tolerance
and use of material occurs due to the tube locking, and,
preferably, end-locking design of the present invention. It is a
further object of the invention to provide folded condenser tube
with tube end-locking design for use in a motor vehicle, folded
from a sheet material to form a multi-port tube.
[0011] It is also an object to provide a method to manufacture
condenser tubes that provides for multi-port tubes with
advantageous characteristics for automotive air conditioning
applications. It is a further object to provide folded condenser
tubes having very tight dimension tolerances, while at the same
time maintaining long life for the `roll` dies.
[0012] In addition, it is an object of the present invention to
provide for a folded tube that is not an integrated part of the
system before brazing, therefore, meeting the performance standards
required while avoiding the problem of perfectly brazing folded
tubes.
[0013] A further objective is to optimize the folded tube
technology by reducing the tube wall thickness and at the same time
to avoid the rigid relationship between total tube height and tube
gauge, thus allowing more flexibility in tube design and
optimization of material usage and reduction in cost.
[0014] In light of the above, there is a need in the art to provide
a folded tube for a heat exchanger of a motor vehicle that achieves
these objectives and desires.
SUMMARY OF THE INVENTION
[0015] The present invention solves a number of problems often
found in extruded technology. Tight dimensional tolerances are
achieved concurrent with achievement of long life spans for the
roll dies used in the process. In its various embodiments, the
present invention, therefore, provides cost benefits compared to
extruded tubes. The present invention also provides surprising
advantages inspite of the fact that in a preferred embodiment a
folded tube is generally not an integrated part of the condenser
prior to brazing.
[0016] Accordingly, the present invention is a multi-port folded
tube for a heat exchanger, and, in particular, a condenser tube,
with an improved tube locking feature. In a preferred embodiment of
the present invention, a multi-port folded tube is formed from
material utilizing the manufacturing process as described
hereinbelow wherein there is at least one tube locking feature. In
preferred embodiments of the present invention, the folded tube
comprises a tube with the at least one tube locking feature of the
present invention, more preferably, the end tube locking
feature.
[0017] The folded tube, and particularly, the multi-port heat
exchanger tube, preferably comprises a base; a top spaced from and
opposing said base; a first side interposed between said base and
said top along one side thereof; a second side interposed between
said base and said top along another side thereof; and each of said
base and said top having at least one internal oriented portion;
wherein the at least one top internal oriented portion abuts the at
least one base internal oriented portion to define a plurality of
fluid ports and wherein there is least one tube locking
feature.
[0018] The folded tube in a preferred embodiment of the present
invention includes a base, a top spaced from and opposing the base,
a first side interposed between the base and the top along one side
thereof, and a second side interposed between the base and the top
along another side thereof. The folded tube also preferably
includes at least one of the base and the top having at least one
internal half web having an initial web width and an initial
outside shoulder radius and capable of potentially being compressed
when the at least one top half web is `face to face` or `aligned`
with at least one base half web to `abut` or `contact` the at least
one top internal half web with the at least one base internal half
web and, defining upon closure, a tube with a plurality of fluid
ports. The folded tube is then `closed` or locked with the end
locking feature as described herein below. Therefore, the present
invention particularly relates to a multi-port folded tube for a
heat exchanger, and, in preferred embodiments, a condenser tube
wherein the folded tube of the present invention includes at least
one of the base and the top from a generally planar sheet having at
least one internal half web essentially aligned face to face and
capable of potentially abutting when compressed, so that when the
at least one top internal half-web is `face to face` or `aligned`
with at least one base internal half-web to abut the at least one
top internal half web with the at least one base internal half web,
closure provides a tube with a plurality of fluid ports. Also,
preferred embodiments of the present invention have at least one
`tube locking` or `closure` feature the tube locking or closure
feature can be either at the tube end or other than at the tube
end. Preferably, the at least one tube locking or closure feature
is found at tube end.
[0019] Also, the present invention is a method of making a
multi-port folded tube for a heat exchanger with at least one tube
locking feature. The method includes the steps of providing a
generally planar sheet, folding the sheet, and forming at least one
internal half web having, preferentially, a first fold portion and
a second fold portion. The method also includes the steps of
aligning the at least one top internal half web and the at least
one base internal half web to aide abutting of the two half webs.
More preferably, the top half web and the base half web are face to
face or directly aligned so as to provide effective multi-port
formation. The method further includes the steps of folding the
sheet and forming a base and a top opposing the base and a first
side interposed between the top and the base and a second side
interposed between the top and the base such that the at least one
internal half web abuts or contacts either one of the top or the
base other half internal webs to provide a plurality of fluid
ports. The end of the tube is formed by having one sheet end of
sheet is bent onto the another sheet end, and then the both locked
ends are bent to form a tube end.
[0020] One advantage of the present invention is that a multi-port
folded tube for a heat exchanger with such a locking feature can be
used on with a variety of heat exchangers. In the case such as a
condenser is provided for an air conditioning system of a motor
vehicle for condensing liquid refrigerant. Another advantage of the
present invention is that the folded tube is stamped and folded and
is more economical to manufacture than an extruded tube. Yet
another advantage of the present invention is that the folded tube
has half webs that do not extend the entire height of the ports to
be formed, and, therefore, do not require compression to make a
folded top or folded bottom tube portion alone that has to extend
to the opposing top or bottom tube portion respectively. Still
another advantage of the present invention is that a method of
making the folded tube is provided whereby various tube-end locking
features may be utilized. Yet a further advantage of the present
invention, particularly in preferred embodiments, is that it
provides a preformed end and support versus a `traditional` closed
end form that allows seams to be formed and held more closely
together, thus eliminating the potential of multiple pin-hole sized
`gaps` at the end seams of the folded tube. Since the gap is
relatively closed, brazing to a header slot, for example, becomes
more efficient and the folded tube more desirable for these
applications.
[0021] In preferred embodiments of the present invention, the
folded tube may be an integrated part of the system before brazing
or not an integrated part of the system before brazing. To avoid
the problem of perfectly brazing folded tubes, a preferred
embodiment of the present invention does not integrate the folded
tube as part of the system prior to brazing.
[0022] Other features and advantages of the present invention will
be readily appreciated, as the same becomes better understood after
reading the subsequent description taken in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1a is a perspective view of a partially closed folded
tube;
[0024] FIG. 1b is a perspective view of the closed folded tube with
the half walls abutting each other;
[0025] FIGS. 2 is a perspective view of a closed folded tube with
the end folded;
[0026] FIGS. 3a is a perspective view of a closed folded tube
according to the present invention, with the end half folded;
[0027] FIGS. 3b is a perspective view of a closed folded tube
according to the present invention, with the a fully closed
end;
[0028] FIGS. 4 is a perspective view of a closed folded tube
according to the present invention, with tube locking feature found
other than at the tube end;
[0029] FIGS. 5 is a perspective view of another closed folded tube
according to the present invention, with tube locking feature found
other than at the tube end;
[0030] FIG. 6 is an elevational view of a folded tube, in
accordance with the present invention, illustrated in operational
relationship with a heat exchanger of a motor vehicle;
[0031] FIG. 7 is a perspective view of a sheet utilized in a method
of making folded tubes in accordance with the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0032] Referring to the drawings and particularly to FIG. 1a, 1b
and FIG. 2 the basic process of tube folding in accordance with the
present invention, and an embodiment of the subsequent tube 49 of
the present invention is illustrated. A sheet material 70 is folded
progressively into a muli-port 50 tube. The sheet 70 is folded to
form several half-webs or internal half webs 40, 44, then bent into
tube form. FIG. 1b shows the half web from the top surface 40 and
the half webs from the base surface 44 face-to-face and abutting
one another at point 51, together forming webs separating
multi-ports.
[0033] Referring to FIG. 2, at one end of the sheet ends 34 and 32,
are bent twice inwardly on one end 34 yielding three layers and
bent once on end 32 yielding 2 layers, together forming a 5-layer
locked tube end 35, yielding specific relations between tube height
and sheet gauge.
[0034] Referring to FIGS. 3a and 3b, the tube locking features
135,235 are formed. In FIG. 3a, one end 132 of the sheet is bent
onto the other end 134 of the sheet 70. Subsequently end 132 and
end 134 form locked end 135 that are bent to form the tube end 235
of FIG. 3b. The two locked sheet ends form another end of the
multi-port tube. The end of the tube is formed by having one sheet
end of sheet is bent onto the another sheet end, and then the both
locked ends are bent to form a tube end.
[0035] Referring to FIG.4, the tube-locking feature 150 is not at
tube end 350. Tube locking feature 150 is found, preferably, at the
top of a middle port 351 of the folded tube 350.
[0036] FIG. 5 shows another preferred embodiment of the present
invention. The tube-locking feature 250, as in FIG. 4, is not found
at tube end. Preferably, the tube-locking feature 250 is found on
the inside tubes 451 yielding a clearance between the two sheet
ends (delta) which does not depend on the sheet width.
[0037] Referring to the drawings and in particular FIG. 6, one
embodiment of a heat exchanger 10, according to the present
invention, such as a condenser for an air conditioning system (not
shown), is shown for a motor vehicle (not shown). The heat
exchanger 10 includes a plurality of generally parallel folded
tubes 49, according to the present invention, extending between
oppositely disposed headers 14, 16. The heat exchanger 10 includes
a fluid inlet 18 for conducting cooling fluid into the heat
exchanger 10 formed in the header 14 and an outlet 20 for directing
cooling fluid out the heat exchanger 10 formed in the header 16.
The heat exchanger 10 also includes a plurality of convoluted or
serpentine fins 22 attached to an exterior of each of the tubes 12.
The fins 22 are disposed between each of the tubes 12. The fins 22
conduct heat away from the tubes 12 while providing additional
surface area for convective heat transfer by air flowing over the
heat exchanger 10. It should be appreciated that, except for the
folded tube 12, the heat exchanger 10 is conventional and known in
the art. It should also be appreciated that the folded tube 12
could be used for heat exchangers in other applications besides
motor vehicles.
[0038] Referring to FIGS. 7a, 7b and 7c, and FIGS. 1 and 2, a
method, according to the present invention, of the making the
folded tube 49 is shown. The method includes the steps of providing
a generally planar sheet 70 of elongate, deformable material coated
with a braze material forming the base 24 and top 26 having their
respective ends 32 and 34 edges along a longitudinal length thereof
as illustrated in FIG. 7A. The ends 32 and 34 of the base 24 and
top 26 can be either flat or arcuate as illustrated in FIGS. 1a, 2,
3a and 3b. Alternatively, for the folded tube 49, 249, 349 and 449,
the ends can be formed as illustrated in FIGS. 3a through 5. The
method includes the step of folding the sheet 70 from the lateral
sides to initially form the internal half webs 40 on the top with
the second internal half web 44 on the base to an initial
predetermined web height and width as illustrated in FIG. 7B. The
method also includes the step of aligning the internal half webs
40, 44 approximately face to face so that they may abut each other.
The method includes the step of folding the ends 32 and 34 toward
one another until they meet to form ports 50 as illustrated in
FIGS. 1b and 2. The method includes the step of connecting the ends
32 and 34 together. The method includes the step of brazing the
folded tube 49 by heating the folded tube 49 to a predetermined
temperature to melt the brazing material to braze the ends 32 and
34 and the internal top half webs 40 to the base half webs 44. The
folded tube 49 is then cooled to solidify the molten braze material
to secure the ends 32 and 34 together and the internal top half
webs 40 and the base half webs 44 together. It should be
appreciated that, instead of the ends 32 and 34, the partition
150,250 of the folded tube 349,449 may be formed internally as in
FIGS. 4 and 5. Accordingly, the folded tube is a cost reduction
over current tubes. The folded tube has internal half webs that are
folded and potentially `squeezed` to maintain a predetermined
distance between the top and base 24. The folded tube also has the
internal half webs forming ports with a defined hydraulic
diameter.
[0039] Preferred embodiments of the present invention, as described
above, and in particular, as exemplified in FIG. 4, and 5 therefore
result in use of less material for tube production, increased
refrigerant cross sectional area availability, and, therefore, less
internal pressure restriction for the air conditioning system. In
one preferred embodiment of the present invention, the folded tube
is a tube having a locking feature supported with a `T` shaped wall
150 such that the end edges would be in the tube's interior side to
maintain an approximately flat wall. In another preferred
embodiment, the locking feature is contained within a `U` shaped
interior wall 451. Preferably, the `U` shaped interior wall is
`doubled` such that the perpendicular end wall portions or edges
would be between the tube's interior walls to maintain closed flat
end wall. More preferred would be `U` shaped walls wherein is
doubled In a preferred method of the present invention, referring
to FIG. 3a the planar sheet is shaped such that the width across
the tube formed therefrom is greater than the height of the tube,
and the edges of the planar sheet have a locking feature 135 In the
form of a `J`.
[0040] The present invention has been described in an illustrative
manner. It is to be understood that the terminology which has been
used is intended to be in the nature of words of description rather
than of limitation.
[0041] Many modifications and variations of the present invention
are possible in light of the above teachings. Therefore, within the
scope of the appended claims, the present invention may be
practiced other than as specifically described.
* * * * *