U.S. patent application number 12/446378 was filed with the patent office on 2011-01-13 for soldered flat tube for condensers and/or evaporators.
This patent application is currently assigned to MODINE MANUFACTURING COMPANY. Invention is credited to Daniel Borst, Frank Vetter, Werner Zobel.
Application Number | 20110005738 12/446378 |
Document ID | / |
Family ID | 39326147 |
Filed Date | 2011-01-13 |
United States Patent
Application |
20110005738 |
Kind Code |
A1 |
Vetter; Frank ; et
al. |
January 13, 2011 |
SOLDERED FLAT TUBE FOR CONDENSERS AND/OR EVAPORATORS
Abstract
The present invention relates to a soldered flat tube for
condensers and/or for evaporators in air-conditioning systems, in
particular in motor vehicles, which can be produced by deformation
of endless aluminum sheet-metal strips, has two narrow sides and
two wide sides and also has inner passages with a hydraulic
diameter which is greater than or equal to 0.254 mm, and the flat
tube has a tube wall thickness of less than 0.25 mm, wherein both
narrow sides are reinforced by having at least double the thickness
of the remaining tube wall thickness.
Inventors: |
Vetter; Frank; (Neuhausen,
DE) ; Zobel; Werner; (Boblingen, DE) ; Borst;
Daniel; (Kongen, DE) |
Correspondence
Address: |
MICHAEL BEST & FRIEDRICH LLP
100 E WISCONSIN AVENUE, Suite 3300
MILWAUKEE
WI
53202
US
|
Assignee: |
MODINE MANUFACTURING
COMPANY
Racine
WI
|
Family ID: |
39326147 |
Appl. No.: |
12/446378 |
Filed: |
November 15, 2007 |
PCT Filed: |
November 15, 2007 |
PCT NO: |
PCT/US2007/084823 |
371 Date: |
September 28, 2010 |
Current U.S.
Class: |
165/177 |
Current CPC
Class: |
F28F 1/022 20130101;
F28F 1/40 20130101; F28F 1/02 20130101 |
Class at
Publication: |
165/177 |
International
Class: |
F28F 1/00 20060101
F28F001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 22, 2006 |
DE |
10 2006 054 814.0 |
Claims
1. A soldered flat tube for one of a condenser and an evaporator in
motor vehicle air-conditioning systems, the tube comprising: one or
more endless aluminum-containing sheet-metal strips shaped so as to
have two narrow sides, two wide sides, and inner passages with a
hydraulic diameter, which is greater than or equal to 0.254 mm; and
a tube wall thickness of less than 0.25 mm; wherein both narrow
sides are reinforced so as to have a thickness of at least two
times the remaining tube wall thickness.
2. The flat tube according to claim 1, wherein the flat tube
comprises three sheet-metal strips, two of the sheet-metal strips
forming the tube wall and the third sheet-metal strip forming an
inner insert.
3. The flat tube according to claim 2, wherein the two sheet-metal
strips which form the tube wall are substantially identical in
form, one longitudinal edge of the sheet-metal strips having a
larger arc and the other longitudinal edge of the sheet-metal
strips being configured with a smaller arc, the sheet-metal strips
being disposed in such a manner with respect to one another that
the larger arc of one longitudinal edge of one of the two
sheet-metal strips engaging around the smaller arc of the
longitudinal edge of the other of the two sheet-metal strips, and
vice versa.
4. The flat tube according to claim 2, wherein the inner insert has
two deformed longitudinal edges which bear against insides of the
narrow sides.
5. The flat tube according to claim 1, wherein the flat tube can be
produced either from one single sheet-metal strip or from two
sheet-metal strips.
6. The flat tube according to claim 1, wherein the flat tube is
formed from two sheet-metal strips, one of the narrow sides
comprising a bend which lies in a fold of one of the sheet-metal
strips, and wherein an other narrow side foamed by a longitudinal
edge of the one of the sheet-metal strips is configured with a
larger arc, which is placed around a smaller arc at an other
longitudinal edge of the one of the sheet-metal strips, an other of
the sheet-metal strips being configured as a corrugated inner
insert, the longitudinal edges of which bear or do not bear against
the inside of the narrow sides.
7. The flat tube according to claim 1, wherein the passage wall
thickness is between about 0.03 mm and about 0.15 mm.
8. The flat tube according to claim 1, wherein the tube wall
thickness is between about 0.08 mm and about 0.20 mm.
9. The flat tube according to claim 1, wherein a small dimension of
the flat tube is between about 0.8 mm and about 1.3 mm and a large
dimension is between about 8 mm and about 20 mm
10. The flat tube according to claim 9, wherein the large dimension
is between about 12 mm and about 16 mm.
11. The flat tube according to claim 1, wherein the hydraulic
diameter is between about 0.30 mm and about 0.70 mm.
12. A condenser or evaporator as a component of an air-conditioning
system of motor vehicles, the condenser or evaporator comprising: a
soldered heat exchanger network made up of flat tubes and fins
which are disposed between the flat tubes and through which cooling
air flows, at least one of the flat tubes including one or more
endless aluminum-containing sheet-metal strips shaped so as to have
two narrow sides, two wide sides, and inner passages with a
hydraulic diameter which is greater than or equal to 0.254 mm; and
a tube wall thickness of less than 0.25 mm; wherein both narrow
sides are reinforced so as to have a thickness of at least two
times the remaining tube wall thickness.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Priority is hereby claimed to German Patent Application No.
DE 10 2006 054 814.0, filed Nov. 22, 2006, the entire contents of
which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a soldered flat tube for
condensers and/or evaporators in air-conditioning systems, and more
particularly, to tubes for condensers and/or evaporator in motor
vehicles. The tubes can be produced by deformation of one or more
aluminum-containing sheet-metal strips, having two narrow sides and
two wide sides. The tubes can include inner passages with a
hydraulic diameter which is greater than or equal to 0.254 mm, and
can have a tube wall thickness of less than 0.25 mm.
SUMMARY
[0003] Soldered flat tubes for condensers are known from EP 273 164
A1. Flat tubes with inner passage hydraulic diameters in the range
from 0.381-1.778 mm are nowadays standard equipment for what are
known as parallel-flow condensers. FIG. 1 of the above-mentioned
document shows a parallel-flow condenser of this type and also
proposes a process for producing condensers of this type. To
produce the flat tubes, a sheet-metal strip is shaped into the flat
tube and welded using a longitudinal seam. A second sheet-metal
strip is formed with corrugations running in the transverse
direction and is inserted into the flat tube. The peaks and valleys
of the corrugations are soldered to the wide sides of the flat
tube, so as to form inner passages running in the longitudinal
direction which have hydraulic diameters within the above-mentioned
range (cf. FIG. 2 of the above-mentioned document).
[0004] In many other cases, flat tubes for condensers and/or
evaporators are produced by extrusion, in which case there are
manufacturing engineering limits on the realization of particularly
small hydraulic diameters combined with significantly smaller tube
wall thicknesses and passage wall thicknesses. From a cost
perspective too, the extrusion process does not always stand
comparison with other processes. This is true at least if the flat
tubes have dimensions (D;d) as required for
condensers/evaporators.
[0005] Furthermore, in the case of flat tubes for condensers and/or
evaporators, it is necessary to take into account the significantly
higher internal pressure compared to other heat exchangers in motor
vehicles, which has meant that in practice hitherto the tube wall
thickness of flat tubes of this type has been at best approximately
between 0.25 mm and 0.30 mm. The hydraulic diameters of current
commercially available flat tubes for condensers and/or evaporators
are in the range from approximately 1.10-1.60 mm or slightly
above.
[0006] There are also a number of earlier patent applications in
the name of the applicant, but these have not at present been
published. One of these bears the application number DE 10 2006 006
670.7 and proposes flat tubes with extremely small wall thicknesses
for cooling liquid coolers and for charge air coolers.
[0007] Another convention heat exchanger is disclosed in EP 1 681
528 A1. This publication specifically claims flat tubes for
condensers. It represents an advanced stage of development, since
it likewise relates to very thin-walled flat tubes. The sheet-metal
strip forming the passages is to have a thickness of less than 0.1
mm. In the Applicant's opinion, the flat tubes disclosed in that
document, despite all their advantages, also have a significant
drawback, namely that the stability of the flat tubes is
insufficient.
[0008] One independent object of the invention is to provide
lightweight but also high-performance and low-cost condensers
and/or evaporators or flat tubes for them which are to have
improved stability. Some embodiments of the present invention
achieve this and other desirable objects.
[0009] According to the invention, both narrow sides of the flat
tube are reinforced in that they are to have a thickness which is
greater than the tube wall thickness, for example at least double
the tube wall thickness. This proposal simplifies production of the
heat exchanger network comprising flat tubes of this type and also
corrugated fins, since this network becomes easier to assemble. In
the case of flat tubes from the prior art, which have only a single
reinforced narrow side, it is necessary to ensure that all the flat
tubes are positioned with the reinforced narrow side facing in one
direction, generally forward toward the cooling-air stream. This
consideration is obviated because the present proposal reinforces
both narrow sides.
[0010] Furthermore, according to an embodiment which is currently
preferred, the flat tube comprises three sheet-metal strips, two
sheet-metal strips forming the tube wall and the third sheet-metal
strip representing an inner insert.
[0011] In a refinement of this idea, the two sheet-metal strips
which form the tube wall are identical in form, in that one
longitudinal edge of the sheet-metal strips has a larger arc and
the other longitudinal edge of the sheet-metal strips is configured
with a smaller arc, the sides of the sheet-metal strips being
disposed oppositely to one another in such a manner that the larger
arc of one longitudinal edge of one sheet-metal strip engages
around the smaller arc of the longitudinal edge of the other
sheet-metal strip, and vice versa.
[0012] Further reinforcement of the two narrow sides is achieved by
the inner insert having two deformed longitudinal edges which bear
against the inside of the narrow sides.
[0013] Alternatives provide for it to be possible to produce the
flat tube either from one single sheet-metal strip or from two
sheet-metal strips.
[0014] In the case of flat tubes which can be produced from two
sheet-metal strips, one narrow side comprises a bend which lies in
a fold of the sheet-metal strip and the other narrow side is formed
by one longitudinal edge of the sheet-metal strip being configured
with a larger arc, which is placed around a smaller arc at the
other longitudinal edge of the sheet-metal strip, the second
sheet-metal strip being configured as a corrugated inner insert,
the longitudinal edges of which bear or do not bear against the
inside of the narrow sides.
[0015] The passage wall thickness is approximately between
0.03-0.10 mm or slightly above. In the case of flat tubes made from
a single sheet-metal strip, the tube wall thickness and the passage
wall thickness have the same dimensions.
[0016] The tube wall thickness is in the range from approximately
0.08 mm-0.20 mm, with the passage wall thickness being between
0.03-0.10 mm. This applies to both two-part and three-part flat
tubes.
[0017] In terms of the flat tube dimensions, the small dimension
(d) of the flat tube is approximately 0.8-1.3 mm and the large
dimension (D) is approximately between 8 and 20 mm, preferably
approximately 12-16 mm.
[0018] It has been concluded that a particularly suitable hydraulic
diameter of the passages is between 0.30 and 0.70 mm, with a range
between 0.40 and 0.60 mm standing out in particular by virtue of
performance advantages.
[0019] The condenser or evaporator as a component of an
air-conditioning system of motor vehicles which condenser or
evaporator has a soldered heat exchanger network made up of flat
tubes and fins which are disposed between the flat tubes and
through which cooling air flows is described in greater detail
below.
[0020] Other aspects of the invention will become apparent by
consideration of the detailed description and accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The accompanying drawings predominantly show a plurality of
enlarged views of various flat tube cross sections, which can
advantageously be used for condensers of air-conditioning systems.
In the drawings:
[0022] FIG. 1 shows a flat tube produced from three sheet-metal
strips;
[0023] FIG. 2 shows a flat tube according to an alternate
embodiment which can be produced from three sheet-metal strips;
[0024] FIGS. 3, 4, 5, and 7a-7d show further modified flat tubes
comprising three sheet-metal strips;
[0025] FIGS. 6, 8, and 9 show different flat tubes which comprise a
single deformed sheet-metal strip; and
[0026] FIG. 10 shows a flat tube which can be produced from two
sheet-metal strips.
DETAILED DESCRIPTION
[0027] Before any embodiments of the invention are explained in
detail, it is to be understood that the invention is not limited in
its application to the details of construction and the arrangement
of components set forth in the following description or illustrated
in the following drawings. The invention is capable of other
embodiments and of being practiced or of being carried out in
various ways. Also, it is to be understood that the phraseology and
terminology used herein is for the purpose of description and
should not be regarded as limiting. The use of "including,"
"comprising," or "having" and variations thereof herein is meant to
encompass the items listed thereafter and equivalents thereof as
well as additional items. Unless specified or limited otherwise,
the terms "mounted," "connected," "supported," and "coupled" and
variations thereof are used broadly and encompass both direct and
indirect mountings, connections, supports, and couplings. Further,
"connected" and "coupled" are not restricted to physical or
mechanical connections or couplings.
[0028] All the flat tubes have the common features whereby the
hydraulic diameter h.sub.D of the passages K is greater than 0.254
mm, the tube wall thickness W.sub.d is less than 0.25 mm and both
narrow sides 1 are reinforced by having a greater wall thickness
S.sub.d than the remaining tube wall thickness W.sub.d. The passage
wall thickness K.sub.d may be between 0.03 and 0.15 mm.
[0029] The flat tubes illustrated in FIGS. 1-3, 5, and 7 comprise
three sheet-metal strips a, b, c and constitute the currently
preferred embodiments, with the flat tubes from FIG. 7 constituting
the variant which is at present most preferred. The flat tubes in
the above-mentioned figures all have the feature that the two
sheet-metal strips a and b which form the wall parts are identical
in form and are arranged oppositely in terms of their sides. One
longitudinal edge of the sheet-metal strips a and b was formed with
a larger arc and the other longitudinal edge was provided with a
smaller arc. As a result of the opposite arrangement, the larger
arc of one sheet-metal strip a engages around the smaller arc on
the other sheet-metal strip 6 in order to form one narrow side 1 of
the flat tube, and the larger arc on the other sheet-metal strip b
engages around the smaller arc on the first sheet-metal strip a in
order to form the other narrow side 1 of the flat tube.
Furthermore, the flat tubes of the above-mentioned figures also
have the common feature that the third sheet-metal strip c
represents an inner insert, the two longitudinal edges of which
bear against the inside of the narrow sides 1 and additionally
reinforce the latter. This text refers to sheet-metal strips a, b,
c, because the flat tubes are produced from endless sheet-metal
strips on a rolling mill train and are then cut to the required
length, which is not shown here.
[0030] FIG. 1 differs from FIG. 2 with regard to the form of the
inner insert c. FIG. 2 shows the possibility of the corrugation
geometry or the configuration of the chambers K possibly being
different, in order to take account of specific thermodynamic
conditions or in order to achieve advantages in this respect.
Furthermore, the left-hand narrow side 1 of the flat tube from FIG.
2 indicates that the inner insert c may also be folded against the
longitudinal edge in order to additionally reinforce the narrow
sides 1. Although this possibility has been shown for only one
longitudinal edge, it will be clear that it is also possible for
both longitudinal edges of the inner insert c to be formed in this
way.
[0031] The exemplary embodiment shown in FIGS. 3 and 4 is
particularly suitable for inner inserts c which are produced from
extremely thin sheet-metal strips. This may mean sheet-metal
thicknesses of 0.03 mm or slightly more. The sheet-metal thickness
of the wall parts a and b is also very small, for example around
0.10 mm. To allow sufficient reinforcement of the narrow sides 1 at
this point too, the longitudinal edges of the inner insert c have
been folded horizontally a number of times and placed against the
inside of the narrow sides 1. The horizontal folds of the
longitudinal edges of the inner insert c mean that here the
thickness S.sub.d of the narrow sides 1 is even a multiple of the
thickness W.sub.d of the remaining tube wall--up to 5-8 times or
even more could quite easily be advantageous.
[0032] The two flat tubes illustrated in FIG. 5 differ in terms of
the geometry of their chambers K and by the fact that the
above-mentioned measure of folding the two longitudinal edges of
the inner insert c has been implemented in the lower of the two
illustrations but not the upper one.
[0033] The four illustrations corresponding to FIGS. 7a-7d differ
firstly with regard to the choice of thickness of the sheet-metal
strips a, b and c and also the hydraulic diameters h.sub.D of the
passages K. The hydraulic diameters in the upper illustration are
smaller, being approximately 0.5 mm. Moreover, the edge
configuration of the inner insert c has been modified slightly. The
lowest values are to be found in the exemplary embodiment
corresponding to FIG. 7d, where the hydraulic diameter h.sub.D is,
for example, approximately 0.455 mm, the tube wall thickness
W.sub.d is approximately 0.115 mm and the passage wall thickness
K.sub.d is approx. 0.05 mm. As is known, the hydraulic diameter
h.sub.D is given by h.sub.D=4.times.A/U, where A represents the
cross-sectional area of the passage K and U represents the wetted
periphery of the passage K.
[0034] FIG. 6 shows suitable embodiments of a soldered flat tube
comprising a single sheet-metal strip. Accordingly, the flat tube
does not have a separate inner insert. Rather, chambers K have been
produced by in each case a fold 10 formed in a wide side 2, said
fold being supported against the other wide side 2. The narrow
sides 1 have in each case been produced from numerous horizontally
disposed folds F which, as shown in the figures, provide a
thickness of the narrow side 1 which amounts to a multiple of the
thickness of the sheet-metal strip.
[0035] FIG. 8 shows another flat tube made from a single
sheet-metal strip in an intermediate stage shortly before
completion. This flat tube is to comprise one sheet-metal strip
with a thickness W.sub.d which is closer to the upper limit, i.e.
could be for example 0.20 mm. The reason for this could be that the
thickness S.sub.d in the narrow sides 1 is only double the
thickness of the sheet-metal strip or the tube wall thickness
W.sub.d.
[0036] By contrast, FIG. 9 shows that it is possible to form very
stable narrow sides 1 even in the case of flat tubes comprising
just one sheet-metal strip. For this purpose, it is then possible
to select a sheet-metal strip with a thickness approximately
between 0.10-0.15 mm. To produce this flat tube, two spaced-apart
folds F are formed in the sheet-metal strip. Then, a bend B is
produced in each of the folds F, thereby forming the narrow sides 1
of the flat tube. However, it is previously also necessary to have
corrugated a portion of the sheet-metal strip, thereby forming the
passages K in the closed flat tube, as shown in the figure.
[0037] Finally, FIG. 10 shows a flat tube with passages K which has
been produced from two sheet-metal strips a, c. The sheet-metal
strip a forms the tube wall, whereas the sheet-metal strip c forms
an inner insert. The sheet-metal strip a may in this case have a
thickness of approximately 0.20 mm. The thickness of the inner
insert c is only approximately 0.15 mm or less, for example 0.10
mm. First of all, a fold F is formed in the sheet-metal strip a. In
this exemplary embodiment, a small arc is formed at one
longitudinal edge of the sheet-metal strip a. The other
longitudinal edge of the sheet-metal strip a may likewise already
have been preformed, so that it can subsequently be placed around
the small arc. The sheet-metal strip c, i.e. the inner insert of
the flat tube, is provided with a corrugated formation and with two
deformed longitudinal edges. Then, the inner insert c is introduced
into the flat tube, which can be gradually closed up. As the flat
tube is being closed up, a bend B is produced in the
above-mentioned fold F, resulting in the formation of the narrow
side 1 located at the top in the figure. In the closed flat tube,
the two longitudinal edges of the inner insert c bear against the
inside of the narrow sides 1 of the flat tube. A number of steps of
the production process described have been illustrated in FIG.
10.
[0038] Various features and advantages of the invention are set
forth in the following claims.
* * * * *