U.S. patent application number 10/875721 was filed with the patent office on 2005-01-13 for heat exchanger useful as charge-air cooler for commercial vehicles.
This patent application is currently assigned to BEHR GmbH & CO. KG. Invention is credited to Emrich, Karsten, Kull, Reinhard, Volker, Cord.
Application Number | 20050006066 10/875721 |
Document ID | / |
Family ID | 33394995 |
Filed Date | 2005-01-13 |
United States Patent
Application |
20050006066 |
Kind Code |
A1 |
Emrich, Karsten ; et
al. |
January 13, 2005 |
Heat exchanger useful as charge-air cooler for commercial
vehicles
Abstract
The invention relates to a heat exchanger, preferably a
charge-air cooler for motor vehicles, comprising: first members
defining a plurality of passageways for guiding a first fluid in
heat exchange relationship with a second fluid flowing over the
outside of the members defining the passageways, and at least one
second member forming a part of the heat exchanger structure in
contact with either the first or second fluid, wherein at least one
of the first members and the second member is comprised of a steel
strip bearing at least one surface layer of aluminum and/or a
brazing material.
Inventors: |
Emrich, Karsten; (Stuttgart,
DE) ; Kull, Reinhard; (Ludwigsburg, DE) ;
Volker, Cord; (Backnang, DE) |
Correspondence
Address: |
FOLEY AND LARDNER
SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
BEHR GmbH & CO. KG
|
Family ID: |
33394995 |
Appl. No.: |
10/875721 |
Filed: |
June 25, 2004 |
Current U.S.
Class: |
165/133 ;
165/177 |
Current CPC
Class: |
F28F 21/084 20130101;
F28D 2021/0082 20130101; Y02T 10/12 20130101; F02B 29/045 20130101;
Y02T 10/146 20130101; F28F 21/089 20130101; F28F 21/082 20130101;
F28F 19/06 20130101 |
Class at
Publication: |
165/133 ;
165/177 |
International
Class: |
F28F 013/18 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 25, 2003 |
DE |
103 28 748.5 |
Claims
What is claimed is:
1. A heat exchanger suitable for use as a charge-air cooler for
motor vehicles, comprising: a plurality of first members defining a
plurality of passageways for guiding a first fluid in heat exchange
relationship with a second fluid flowing over the outside of the
members defining the passageways, and at least one second member
forming a part of the heat exchanger structure in contact with
either the first or second fluid, wherein at least one of the first
members and the second member is comprised of a steel strip bearing
on one or both surfaces at least one layer selected from aluminum
and a brazing material.
2. A heat exchanger as claimed in claim 1, wherein the first
members comprise tubes for guiding the first fluid, and the at
least one second member is at least one selected from fins arranged
between the tubes and connected to the tubes in a thermally
conductive manner, at least one header plate for the tubes, at
least one collector tank attached to the header plate, and a
turbulence plate.
3. A heat exchanger as claimed in claim 1, wherein the steel strip
bears at least one layer of aluminum.
4. A heat exchanger as claimed in claim 3, wherein the layer of
aluminum is applied to both sides the steel strip.
5. A heat exchanger as claimed in claim 4, wherein the steel strip
is formed as a cold strip clad with Al on both sides.
6. A heat exchanger as claimed in claim 1, wherein the steel strip
bears a layer of aluminum and a layer of brazing material applied
to the layer of aluminum.
7. A heat exchanger as claimed in claim 1, wherein the thickness of
the layer of Al is approx. 4 to 40% of the thickness of the steel
strip
8. A heat exchanger as claimed in claim 7, wherein the thickness of
the layer of Al is approx. 8% of the thickness of the steel
strip.
9. A heat exchanger as claimed in claim 1, wherein the thickness of
the layer of Al is approx. 0.005 to 0.5 mm.
10. A heat exchanger as claimed in claim 9, wherein the thickness
of the layer of Al is approx. 0.01 to 0.2 mm.
11. A heat exchanger as claimed in claim 2, wherein the tube is
designed as a flat tube and is welded with a longitudinal seam.
12. A heat exchanger as claimed in claim 2, wherein the tube is
brazed by means of a longitudinal seam.
13. A heat exchanger as claimed in claim 1, wherein the first
members comprise a stack of plates or disks.
14. A heat exchanger as claimed in claim 2, wherein the second
member comprises a plurality of fins, and the fins are brazed to
the outer sides of the tubes.
15. A heat exchanger as claimed in claim 2, wherein the second
members comprise turbulence inserts positioned in the internal
cross section of the tubes and which are brazed to the inner side
of the tube.
16. A heat exchanger as claimed in claim 1, comprising a charge air
cooler for a vehicle.
17. In a motor vehicle of the type embodying a charge air cooler,
the improvement comprising the charge air cooler comprising a
charge air cooler as defined in claim 16.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
[0001] The right of foreign priority under 35 U.S.C. .sctn.119(a)
is claimed based on Federal Republic of Germany Priority
Application 103 28 748.5, filed Jun. 25, 2003, the entire
disclosure of which, including the specification, drawings, claims
and abstract, is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The invention relates to a heat exchanger, in particular a
charge-air cooler for vehicles.
[0003] Known heat exchangers, in particular for motor vehicles, are
usually made from aluminum or aluminum alloys. A heat exchanger of
this type, as disclosed for example by DE-A 198 57 435, comprises a
heat exchanger grid with fins and corrugated or web-like fins which
are arranged between the fins and are brazed to the outer surfaces
of the tubes, which are generally flat or rectangular tubes. The
ends of the tubes themselves are held in header plates of collector
tanks and are brazed to the header plates. For the brazing
operation, at least a portion of the parts to be brazed is provided
with a layer of brazing material or braze cladding comprising a
brazing material alloy, e.g., Al--Si. The tubes of the charge-air
coolers have hot charge air flowing through them, and after it has
been cooled in the charge-air cooler, this air is fed to the
internal combustion engine of the motor vehicle. After it has been
compressed, the temperature of the charge air may reach 200 to over
300 degrees Celsius before entering the charge-air cooler. The
outer side of the tubes, whose exchange surface area is increased
by means of the fins, is cooled by ambient air. The strength of
aluminum decreases at temperatures over 150 degrees Celsius, which
has adverse effects in particular on the components of a heat
exchanger that are directly exposed to such a temperature. One way
to satisfy these high demands imposed on the temperature resistance
of the material, for example, is to increase the wall thickness of
the tubes, but this inevitably leads to an increased weight and
also to a drop in the heat conduction, and the drop in strength
generally cannot be compensated for completely at an economically
viable cost. This problem is not restricted to the above-mentioned
type of charge-air coolers with flat tubes, but rather also occurs
in the case of aluminum heat exchangers of plate-type or stacked
design, in which the flow passages or "tubes" are formed by plates
or disks, e.g., as described in DE-A 195 11 991 (corresponding to
U.S. Pat. No. 5,931,219, the entire disclosure of which is
incorporated by reference herein).
SUMMARY OF THE INVENTION
[0004] Therefore, it is one object of the present invention to
improve a heat exchanger of the type described in the introduction
with regard to its hot strength, in particular the hot strength of
the tubes.
[0005] In particular, it is an object of the invention to improve
the hot strength of the heat exchanger components without the
weight of the heat exchanger increasing significantly as a result,
and to provide that the heat exchanger can, if appropriate, be
produced using known processes without significant changes.
[0006] In accomplishing the foregoing objects, there has been
provided in accordance with one aspect of the invention a heat
exchanger suitable for use as a charge-air cooler for a motor
vehicle, comprising: a plurality of first members defining a
plurality of passageways for guiding a first fluid in heat exchange
relationship with a second fluid flowing over the outside of the
members defining the passageways, and at least one second member
forming a part of the heat exchanger structure in contact with
either the first or second fluid, wherein at least one of the first
members and the second member is comprised of a steel strip bearing
on one or both surfaces at least one layer selected from aluminum
and a brazing material.
[0007] Further objects, features and advantages of the present
invention will become apparent from the detailed description of
preferred embodiments that follows, when considered together with
the accompanying figures of drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] An exemplary embodiment of the invention is illustrated in
the drawing and described in more detail in the text which follows,
in which:
[0009] FIG. 1 is a cross-section through a steel strip which is
coated with aluminum on both sides;
[0010] FIG. 2 is a cross-sectional view through a rectangular tube,
coated on the inside and outside; and
[0011] FIG. 3 is a perspective view of an illustrative charge air
cooler in accordance with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0012] According to the invention, the tubes, header plates,
collector tanks and/or turbulence plates of the heat exchanger are
made from a steel strip which is clad or coated with aluminum on
one or both sides. The core material of the tube therefore consists
of steel, i.e., a high-strength material which retains its strength
even at relatively high temperatures. One or both outer sides of
the steel strip are provided with a layer of aluminum which, on the
one hand, protects the core material from corrosion and, on the
other hand, allows the tubes to be brazed to the fins and to the
header plate. This improvement to the strength and, in particular,
the hot strength of the tube material is virtually neutral in terms
of weight, i.e., does not result in a greater tube weight compared
to aluminum tubes of greater wall thickness.
[0013] The term "tubes" is in general to be understood as meaning
flow passages which can be produced from the aluminum-clad steel
strip according to the invention, i.e., for example flat tubes or
pairs of disks or plates that form fluid flow passageways between
them. The term "steel" is also to be understood as encompassing any
equivalent material with a high hot strength. The term "turbulence
plate" is also to be understood as meaning a fin, such as, for
example, a corrugated fin. The term "header plate" is to be
understood as meaning that part of a collection vessel which has
openings for receiving the tubes, so that the tubes can be
connected so as to communicate with the collection vessel. The term
"aluminum" is intended to include layers of pure aluminum as well
as the usual aluminum alloys used to make heat exchangers.
[0014] According to a further independent and advantageous feature
to the invention, the core material of the tubes, header plates,
collector tanks and/or turbulence plates is likewise steel, coated
on both sides with an aluminum brazing material, e.g., clad with an
Al--Si alloy. In this case too, the brazing material cladding
protects the base material from corrosion and allows it to be
brazed to fins and header plates, while at the same time the
strength of the tubes is increased.
[0015] According to a further advantageous embodiment of the
invention, the layer of aluminum is applied to both sides of the
core material. In this context, it is advantageous that the inner
side of the tube can also be brazed to further parts, e.g.,
turbulence inserts. It is therefore possible to produce the same
type of heat exchanger or charge-air cooler even though the core
material for the tubes has been changed.
[0016] According to a further advantageous embodiment of the
invention, the material of the tubes, header plates, collector
tanks and/or turbulence plates is produced from a cold strip, i.e.,
a cold-rolled steel sheet, which has been clad with aluminum on
both sides, i.e., the base material and the claddings are, as it
were, produced in a single operation.
[0017] According to further advantageous embodiments of the
invention, the tubes can be welded or brazed along a longitudinal
seam. This reduces the production costs, for example, compared to
extruded tubes.
[0018] According to a further advantageous embodiment of the
invention, a layer of brazing material, e.g., a known Al--Si,
(aluminum-silicon, alloy) is additionally applied to the layer of
aluminum. This allows fins and plates to be brazed to the tubes
without the fins and tubes themselves having to be brazing
material-clad. It is therefore sufficient for the layer of brazing
material to be arranged either on the tubes or on the fins and the
header plate to ensure that there is a sufficient supply of brazing
material available in the brazing process. Of course, this also
applies to the inner sides of the tube and to the brazing of
turbulence plates.
[0019] According to a further advantageous embodiment of the
invention, the thickness of the layer of aluminum is approximately
4 to 40%, in particular, approximately 8%, of the thickness of the
core material, i.e., of the steel strip. This is sufficient for the
intended functions, such as corrosion prevention and brazing. A
thickness of the aluminum layer of from 0.005 to 0.5 mm, in
particular 0.01 to 0.2 mm, is preferred.
[0020] According to an advantageous general aspect of the
invention, the composite material that has been coated in
accordance with the invention is used to produce heat exchangers,
in particular its tubes, header plates, collector tanks and/or
turbulence plates. Whereas the majority of the components can be
produced from lightweight, brazable or weldable material, a core
material with a high hot strength and a corrosion-resistant,
brazable or weldable covering is used for the highly stressed
components. The overall heat exchanger can therefore be produced in
lightweight form with a high hot strength.
[0021] Turning now to the drawings, FIG. 1 shows a cross-section
through a coated steel strip 1 which has a relatively thick core
layer 2 of steel or a similar material, i.e., a material with
similar properties. An aluminum layer or coating 3, 4 is applied on
the top surface and also on the bottom surface of the steel strip,
i.e., is fixedly joined to the core layer 2. This composite
material can be produced by rolling, for example, as a cold strip
clad with aluminum on both sides, i.e., a steel sheet is
cold-rolled and clad with the layer of aluminum, which may amount
to approximately 4 to 40%, in particular 8%, of the wall thickness
of the steel strip. In addition, it is also possible for braze
claddings, which likewise consist of an aluminum alloy, but alloyed
with Si (silicon) or other additives which reduce the melting
point, to be applied to one or both of the two layers of aluminum
or to one or both sides of the steel strip.
[0022] FIG. 2 shows a tube 5 for a heat exchanger (not shown in
more detail), preferably a charge-air cooler, comprising the strip
material shown in FIG. 1. The aluminum-coated strip 1 shown in FIG.
1 is shaped in a manner known per se on a roll-forming device to
form a tube section, as diagrammatically illustrated in the
drawing, and is closed off at its narrow side 5a by a longitudinal
weld seam 6 or prepared for subsequent brazing by forming a local
overlap in the wall. FIG. 2 uses the same reference numerals as
FIG. 1 for corresponding elements.
[0023] It can be seen that the tube 5 is provided with a layer of
aluminum 3, 4 on both the inner side and the outer side. In
addition, layers of brazing material 7, 8, which may consist of an
Al--Si alloy and which are applied by cladding prior to welding of
the tube, are preferably, for some uses, applied to both the outer
side and the inner side of the tube 5. The tube 5 is used for the
grid of the charge-air cooler. Charge air flows through the
internal cross section 9 of the tube 5, and ambient air flows on
its outer side. Air fins (not shown) are arranged at the
longitudinal sides 5b, 5c of the tube 5 and brazed to the tube,
which is made possible by the brazing coating 7. The fins, which
are made from aluminum, therefore do not themselves have to be
provided with a cladding of brazing alloy.
[0024] The internal cross section 9 of the flat tube 5 may be
filled by a turbulence plate (not shown) which is brazed to the
inner sides of the flat tube by means of the brazing material
coating 8. A turbulence plate of this type is advantageous with a
view to increasing the heat transfer and the ability to withstand
internal pressure (anchoring ftunction) in particular for
charge-air tubes. The use of aluminum-coated steel strip for these
turbulence plates is likewise advantageous with a view to
increasing the ability to withstand internal pressure.
[0025] FIG. 3 shows , in a perspective, partially broken-away view,
one preferred embodiment of a heat exchanger suitable for use as a
charge air cooler, in accordance with the present invention. The
heat exchanger 610 comprises a tank 620 formed from a header plate
630 and a tank cover 640, whereby a chamber 650 for distribution of
a first fluid to be cooled, e.g. air, is arranged inside the tank
620. Tubes 670 are inserted through holes 660 of the header plate
630, the tube ends 680 of said tubes illustrating the plural layer
structure according to the invention. Via the tube ends 690
opposite to said tube ends 680, the tubes 670 discharge into a
second tank indicated by a header plate 700, for collection of the
fluid to be cooled. A cooling fluid, e.g. also air, flows through
the spacings between the tubes, corrugated fins 710 being arranged
in the spacings in order to increase the amount of transferred
heat.
[0026] As has already been mentioned, the composite material
according to the invention can also be used for any high
temperature heat exchanger, as well as for other types of heat
exchangers, e.g., for plate-type or (stacked) disk-type heat
exchangers. The flow passages are in this case formed by pairs of
plates or disks which are brazed to one another on the peripheral
side and on the inside are brazed to turbulence inserts and on the
outside to fins made from aluminum.
[0027] The foregoing description of preferred embodiments of the
invention has been presented for purposes of illustration and
description only. It is not intended to be exhaustive or to limit
the invention to the precise form disclosed, and modifications and
variations are possible and/or would be apparent in light of the
above teachings or may be acquired from practice of the invention.
The embodiments were chosen and described in order to explain the
principles of the invention and its practical application to enable
one skilled in the art to utilize the invention in various
embodiments and with various modifications as are suited to the
particular use contemplated. It is intended that the scope of the
invention be defined by the claims appended hereto and that the
claims encompass all embodiments of the invention, including the
disclosed embodiments and their equivalents.
* * * * *