U.S. patent application number 09/884447 was filed with the patent office on 2002-02-21 for folded tube for heat exchanger, and heat exchanger including such tubes.
Invention is credited to Laveran, Jean-Louis.
Application Number | 20020020522 09/884447 |
Document ID | / |
Family ID | 8851507 |
Filed Date | 2002-02-21 |
United States Patent
Application |
20020020522 |
Kind Code |
A1 |
Laveran, Jean-Louis |
February 21, 2002 |
Folded tube for heat exchanger, and heat exchanger including such
tubes
Abstract
The invention relates to a tube for a heat exchanger, consisting
of a metal strip having an inner face and an outer face, this strip
having two extremities which are folded locally towards the inner
face of the tube so as to form two borders (28, 30) placed one
beside the other. Passages (38) are formed in at least one of the
extremities of the metal strip for introduction of a brazing flux.
These passages (38) can be formed in the two extremities of the
metal strip, and offset with respect to one another. The passages
extend over a distance greater than the height of the borders (28,
30) in such a way as to form an inlet (40) for the brazing
flux.
Inventors: |
Laveran, Jean-Louis;
(Asnieres S/seine, FR) |
Correspondence
Address: |
Liniak, Berenato, Longacre & White
Suite 240
6550 Rock Spring Drive
Bethesda
MD
20817
US
|
Family ID: |
8851507 |
Appl. No.: |
09/884447 |
Filed: |
June 20, 2001 |
Current U.S.
Class: |
165/177 ;
165/181 |
Current CPC
Class: |
F28D 1/0391 20130101;
B21C 37/151 20130101 |
Class at
Publication: |
165/177 ;
165/181 |
International
Class: |
F28F 001/00; F28F
001/20 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 21, 2000 |
FR |
00 07941 |
Claims
1. Tube for a heat exchanger, consisting of a metal strip having an
inner face and an outer face, this strip having two extremities
which are folded locally towards the inner face of the tube so as
to form two borders (28, 30) placed one beside the other,
characterized in that passages (38) are formed in at least one of
the extremities of the metal strip for introduction of a brazing
flux.
2. Tube according to claim 1, characterized in that passages (38)
are formed in the two extremities of the metal strip.
3. Tube according to claim 2, characterized in that the passages
(38) of one extremity are offset with respect to the passages (38)
of the other extremity of the metal strip.
4. Tube according to claim 1, characterized in that the passages
(38) are produced by knurling of the extremities of the metal
strip.
5. Tube according to claim 4, characterized in that the metal strip
is folded by passing through a series of successive rollers, and in
that the knurling is carried out before passing through the forming
rollers.
6. Tube according to claim 1, characterized in that the passage
(38) are produced substantially perpendicularly to the extremities
of the metal strip.
7. Tube according to claim 1, characterized in that the passages
(38) are produced obliquely with respect to the extremities of the
metal strip.
8. Tube according to claim 1, characterized in that the passages
extend over a distance greater than the height of the borders (28)
and (30) in such a way as to form an inlet (40) for the brazing
flux.
9. Tube according to claim 1, characterized in that the outer face
of the metal strip is covered with a plating of brazing alloy.
10. Heat exchanger, especially for a motor vehicle, comprising a
bank of tubes (16) alternating with cooling spacers (15),
characterized in that the tubes are in accordance with claim 1.
11. Method of manufacturing a tube for a heat exchanger, as defined
in claim 1, by folding and brazing of a metal strip, this strip
including an inner face and an outer face, characterized in that a
brazing flux is deposited solely on the outer face of the tube.
12. Manufacturing method according to claim 11, characterized in
that the brazing flux is deposited on the outer face of the metal
strip by spraying.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to a folded tube suitable for forming
part of a heat exchanger such as a radiator for cooling a
motor-vehicle engine, for example.
[0002] It relates more particularly to a folded tube for a heat
exchanger, consisting of a metal strip having an outer face and an
inner face, this strip having two extremities folded locally
towards the inner face of the tube so as to form two borders placed
one beside the other.
[0003] Tubes of this type are already known. After folding, they
are assembled with spacers or fins, placed in a furnace and brazed.
The brazing alloy is generally added by way of a plating of brazing
alloy arranged on the outer face of the metal strip, while the
inner face is coated with an anti-corrosion plating.
[0004] In order to achieve high-quality brazing, it is necessary to
add a brazing flux which has the function of protecting the metal
against oxidation during the brazing. According to the present-day
technique, the brazing flux is deposited by immersion coating. This
gives rise to the situation that the two faces of the metal strip,
both the inner face and the outer face, are coated with brazing
flux. After brazing, residues prejudicial to the internal corrosion
resistance of the radiator are left behind.
[0005] The precise object of the present invention is a tube for a
heat exchanger and a method of manufacturing this tube, embodiments
of which may at least partially remedy these drawbacks.
BRIEF SUMMARY OF THE INVENTION
[0006] This can be achieved by the fact that passages are formed in
at least one of the extremities of the metal strip for introduction
of a brazing flux. By virtue of these passages, the brazing flux
can penetrate between the side-by-side borders, which prevents them
oxidizing.
[0007] According to a variant embodiment, passages are formed in
the two extremities of the metal strip. In this case, the passages
at one extremity are advantageously offset with respect to the
passages of the other extremity of the metal strip.
[0008] According to one embodiment, the passages are produced by
knurling of the extremities of the metal strip. The metal strip is
preferably folded by passing through a series of successive
rollers, and the knurling is carried out before passing through the
forming rollers.
[0009] The passages can be formed substantially perpendicularly to
the extremities of the metal strip or obliquely with respect to
these extremities.
[0010] The passages preferably extend over a distance greater than
the height of the borders in such a way as to form an inlet for the
brazing flux.
[0011] The invention also relates to a heat exchanger, especially
for a motor vehicle, comprising a bank of tubes alternating with
cooling spacers, in which the tubes are in accordance with the
invention.
[0012] Finally, the invention relates to a method of manufacturing
a tube for a heat exchanger by folding and brazing of a metal
strip, this strip including an inner face and an outer face.
[0013] According to the method of the invention, a brazing flux is
suitably deposited solely on the outer face of the tube, preferably
by spraying.
[0014] Other characteristics and advantages of the present
invention will emerge further upon reading the description which
follows of an embodiment example given purely illustratively with
reference to the attached figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In these figures:
[0016] FIG. 1 is an overall view of a heat exchanger for which a
tube in accordance with the present invention is intended;
[0017] FIG. 2 is a view in cross section of a tube in accordance
with the present invention;
[0018] FIGS. 3 and 4 are partial views on an enlarged scale,
respectively in cross section and from above, of the tube
represented in FIG. 2; and
[0019] FIG. 5 is a partial view, on an enlarged scale, in
perspective, of the tube represented in FIGS. 2 to 4.
DETAILED DESCRIPTION OF THE INVENTION
[0020] The heat exchanger represented in FIG. 1 comprises a tube
bank 10 mounted between two manifold chambers 12 and 14. The bank
10 consists of a multiplicity of tubes 16 arranged parallel to each
other and alternating with spacers 15. These spacers, also called
fins, are of the corrugated type. They are formed from metal foil
which is folded so as to constitute corrugations. Hence, a spacer
15 arranged between two adjacent tubes 16 comes into contact with
two tubes via end regions of the corrugations.
[0021] The heat exchanger further includes two checks 17, also
called crosspieces, which frame the tube bank and are arranged
parallel to the tubes 16.
[0022] The pieces which constitute the exchanger are held assembled
on a table (not represented) and pressure is exerted on the checks
17 in the direction of the arrows F so as to hold the tubes 16,
spacers 15 and checks 17 respectively with a view to the brazing
operation.
[0023] The tube 16 represented in FIG. 2 is produced from a metal
strip, for example of aluminum, folded in several successive
operations by virtue of rollers according to a known technique.
This is a flat tube which features a substantially rectangular,
very much flattened, section comprising two large faces 18 and 20
linked by two semi circular faces 21.
[0024] The large face 18 consists of two parts 24 and 26 which are
joined together. The metal strip is folded at right angles to the
extremities of the parts 24 and 26 so as to form side-by-side
borders 28 and 30 which bear on the large face 20, on the inside of
the tube. These borders 28 and 30 have the function, on the one
hand, of delimiting separate circulation channels 32 and 34 for a
fluid, and, on the other hand, of constituting a distance piece
between the two large faces 18 and 20 so as to guarantee that they
are parallel and flat.
[0025] In order to allow brazing of the tube, the metal strip is
covered externally with a brazing plating (not represented), the
inner face being covered with an anti-corrosion plating (not
represented). As can be seen, the borders 28 and 30 are placed one
beside the other in such a way that the gap which may remain
between them is too restricted to allow a brazing flux to be
brought in between these borders.
[0026] For this reason, in accordance with the invention, as can
can be seen more particularly in FIGS. 3 to 5, passages 38 have
been formed in the borders 28 and 30. Although, in the embodiment
described, passages 38 had been provided in each of the two borders
28 and 30, it is also possible, according to a variant embodiment,
to provide such passages only in one of the two borders.
[0027] In the embodiment example described, the passages 38 are
substantially perpendicular to the large faces 18 and 20. This
characteristic is not essential, and it would also be possible, in
accordance with the invention, to provide passages arranged
obliquely with respect to these walls. Likewise, in the embodiment
described, the passages are straight-line, but they could also
exhibit another shape, for example curved or sinusoidally shaped.
As can be seen in FIG. 4, the passages are preferably arranged
alternately, one passage 38 of the border 30 being arranged between
two passages of the border 28, and vice versa.
[0028] Further preferably, as can be seen in FIG. 3, the length of
the passage 38 formed at the extremity of the metal strips is
substantially greater than the height of the borders 28 and 30 in
such a way as to constitute an inlet 40 which facilitates the
introduction of the brazing flux.
[0029] This brazing flux is arranged only on the outer face of the
metal strip, preferably by spraying, but it could also be added by
another technique, for example by immersion coating.
* * * * *