U.S. patent application number 14/711612 was filed with the patent office on 2015-11-19 for exhaust-gas heat exchanger made of duplex steel.
The applicant listed for this patent is Benteler Automobiltechnik GmbH. Invention is credited to Eugen AUL, Fabian FRICKE, Rainer VOESGEN.
Application Number | 20150330719 14/711612 |
Document ID | / |
Family ID | 53385454 |
Filed Date | 2015-11-19 |
United States Patent
Application |
20150330719 |
Kind Code |
A1 |
AUL; Eugen ; et al. |
November 19, 2015 |
EXHAUST-GAS HEAT EXCHANGER MADE OF DUPLEX STEEL
Abstract
The present invention relates to an exhaust-gas heat exchanger
for a motor vehicle, having an outer casing and plates arranged
therein lying one above another in layers, wherein a fin plate made
of austenitic steel material is arranged in an inner cassette made
of ferritic steel material or made of duplex steel and at least two
inner cassettes are arranged one above another like plates and the
outer casing is formed from duplex steel and engages around the
inner cassettes.
Inventors: |
AUL; Eugen; (Hameln, DE)
; VOESGEN; Rainer; (Salzkotten, DE) ; FRICKE;
Fabian; (Paderborn, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Benteler Automobiltechnik GmbH |
Paderborn |
|
DE |
|
|
Family ID: |
53385454 |
Appl. No.: |
14/711612 |
Filed: |
May 13, 2015 |
Current U.S.
Class: |
165/159 |
Current CPC
Class: |
F28F 3/025 20130101;
F28D 21/0003 20130101; F28F 21/082 20130101; F28F 19/00 20130101;
F28D 9/0006 20130101; F28F 9/001 20130101; F28F 3/02 20130101; F28F
21/083 20130101; F28D 9/0031 20130101 |
International
Class: |
F28F 3/02 20060101
F28F003/02 |
Foreign Application Data
Date |
Code |
Application Number |
May 14, 2014 |
DE |
102014106807.6 |
Claims
1. An exhaust-gas heat exchanger for a motor vehicle, having an
outer casing and plates arranged therein lying one above another in
layers, wherein a fin plate made of austenitic steel material is
arranged in an inner cassette made of ferritic steel material or
made of duplex steel and at least two inner cassettes (are arranged
one above another plate-like and the outer casing is formed from
duplex steel and engages around the inner cassettes.
2. The exhaust-gas heat exchanger as claimed in claim 1, wherein a
first flow duct is formed between an inner lateral surface of the
casing and an outer lateral surface of the inner cassettes.
3. The exhaust-gas heat exchanger as claimed in claim 1, wherein a
second flow duct is formed in the inner cassettes.
4. The exhaust-gas heat exchanger as claimed in claim 1, wherein
the inner cassettes are embodied in a two-shell form by two shells,
the two shells being soldered to one another.
5. The exhaust-gas heat exchanger as claimed in claim 4, wherein
the shells of the inner cassettes have outwardly directed spacing
bosses.
6. The exhaust-gas heat exchanger as claimed in claim 1, wherein
the casing has inwardly directed spacing bosses.
7. The exhaust-gas heat exchanger as claimed in claim 1, wherein
the casing is embodied as an outer shell in a two-shell form by two
shells, the two shells being soldered to one another.
8. The exhaust-gas heat exchanger as claimed in claim 1, wherein
the duplex steel used is an alloy of the number 1.4462 or 1.4362 or
1.4162.
9. The exhaust-gas heat exchanger as claimed in claim 1, wherein
brackets made of duplex steel are arranged on the casing.
10. The exhaust-gas heat exchanger as claimed in claim 9, wherein
the brackets are formed in a one piece and materially integral form
on the casing.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of German Application
No. 10 2014 106 807.6, filed May 14, 2014, which is incorporated
herein by reference in its entirety.
[0002] The present invention relates to an exhaust-gas heat
exchanger for a motor vehicle as per the features in the preamble
of patent claim 1.
[0003] During the combustion of fuel, the chemical energy present
in the fuel is converted on the one hand into mechanical energy and
on the other hand into heat energy. In the thermodynamic cycle
process performed by the ideal Carnot process, the efficiency of an
internal combustion engine is limited to approximately 40%, and
therefore approximately 60% of the energy present in the fuel is
converted into heat and carried away with the exhaust gas or else
carried away by way of the exhaust-gas flow or else the engine
block of the internal combustion engine. Exhaust-gas heat
exchangers are known from the prior art which are used on internal
combustion engines for the most part in motor vehicles for cooling
the exhaust gas which arises during the combustion of fuel or for
extracting heat energy therefrom.
[0004] The exhaust gas in this case is at temperatures of more than
500.degree. C. up to 1000.degree. C.
[0005] For reducing pollutants in the form of exhaust-gas
recirculation or else also for extracting the heat present in the
exhaust gas and feeding it, for example, to a thermodynamic cycle
process, it is now necessary to use an exhaust-gas heat
exchanger.
[0006] An exhaust-gas heat exchanger of this type is firstly
exposed directly to the high temperatures of the exhaust gas, and
therefore there may be considerable thermal fluctuations during
operation of the exhaust-gas heat exchanger but also in the
cold-start behavior of an internal combustion engine. In addition,
the exhaust gas itself has highly corrosive properties, and
therefore the material and in particular the lateral surfaces and
the coupling points of the exhaust-gas heat exchanger are
accordingly attacked over the duration of operation.
[0007] A corresponding exhaust-gas heat exchanger is known, for
example, from DE 10 2006 029 110 A1.
[0008] It is an object of the present invention to reduce the
component weight and in particular the production costs of an
exhaust-gas heat exchanger given an at least constant or else
increased service life and also heat transfer properties.
[0009] The aforementioned object is achieved according to the
invention in the case of a motor vehicle heat exchanger having the
features in patent claim 1.
[0010] Advantageous embodiment variants of the present invention
are the subject matter of the dependent patent claims.
[0011] The exhaust-gas heat exchanger according to the invention is
for a motor vehicle and has an outer casing and plates arranged
therein lying one above another in layers. Said exhaust-gas heat
exchanger is characterized by the fact that an interior fin plate
made of austenitized steel material is arranged in an inner
cassette made of ferritic steel material or made of duplex steel
and in turn at least two of the inner cassettes are arranged one
above another plate-like and the outer casing is formed from duplex
steel and engages around the inner cassettes.
[0012] It is thus possible to provide a plate heat exchanger which
has a weight saving of up to 30%, and therefore optimum
coordination is realized by the use of various materials. It is
therefore possible in particular to reduce the wall thicknesses of
the casing, given an at least constant strength and corresponding
durability and corrosion resistance. A possible increase in price
for the material used for the casing is compensated for by the
lower percentage use in terms of mass, and therefore what is
provided overall is an exhaust-gas heat exchanger which is highly
resistant to corrosion. At the same time, the selection of
materials which differ from one another makes it possible to
optimally compensate for various thermal expansions, in particular
also taking into consideration coupling points, in particular
soldered seams, present between the components.
[0013] In the exhaust-gas heat exchanger according to the
invention, a first flow duct is formed between an inner lateral
surface of the casing and an outer lateral surface of the inner
cassettes and a second flow duct is formed in the inner cassettes
themselves. In order that the surface area for a transfer of heat
is now increased within the inner cassettes, a fin plate is
arranged in the inner cassette itself. The fin plate itself has an
undulating or else also a sawtooth-like configuration in cross
section. The fin plate is formed from austenitic steel material and
is positioned in the inner cassette. In a preferred embodiment
variant, the fin plate itself can also be coupled to the inner
cassette, for example by an integral joining method and here in
particular a soldering method. This in turn makes it possible that
the heat energy taken up by way of the fin plate is passed on in
particular at the coupling points to the material of the inner
cassette and then from the inner cassette itself via the wall of
the inner cassette to an outer lateral surface of the inner
cassette and a medium flowing over it.
[0014] In order to realize simple processability and cost-effective
production, the inner cassette is embodied in a two-shell form by
two shells, the two shells being soldered to one another. The two
shells substantially have a U-shaped configuration in cross
section, these then being insertable into one another from above
and below with respect to a vertical direction, so as to
incorporate the fin plate, and being coupled by an integral joining
method, in particular a soldering method. At the same time, it is
then also possible for the fin plate to be coupled to the inner
shell.
[0015] In order that two inner cassettes are then spaced apart from
one another so as to form a flow duct located therebetween, the
inner cassettes have outwardly directed spacing bosses. The inner
cassettes which respectively lie right on the outside then bear by
way of their spacing bosses against the inner lateral surface of
the casing. It is optionally possible for the casing to also have
inwardly directed spacing bosses. The spacing bosses here
furthermore increase the surface area respectively available for
the heat exchanger performance, and this further increases the
cooling power. Furthermore, the ends of the inner cassettes are
formed in a manner tapering toward one another. In this way, the
cross section for the incoming or outgoing exhaust gas on the
exhaust-gas inlet side and, respectively, the exhaust-gas outlet
side is then kept as large as possible, and this proves
advantageous for a very low pressure loss of the exhaust-gas heat
exchanger according to the invention. By virtue of the further
reduction in wall thickness on account of the use, according to the
invention, of duplex steel, the pressure loss is additionally
reduced, given an at least constant cooling power. The spacing
bosses, which can also be in the form of bulges, expand during a
soldering operation, and therefore a high-quality soldered
connection is obtained.
[0016] The at least two inner cassettes are then stacked one above
another and positioned in the casing. For this purpose, it is
particularly preferable in turn that the casing is embodied as an
outer shell in a two-shell form by two shells, the two shells being
soldered to one another. For this purpose, the shells of the casing
are in turn of U-shaped configuration in cross section and are
insertable into one another with the respectively free ends of the
U and can be coupled to one another by way of a thermal joining
process, in particular a soldering process.
[0017] A duplex steel of the alloy 1.4462 or 1.4362 or 1.4162 is
used with particular preference for the duplex steel of the casing
and, if duplex steel is used for an inner cassette, for this too.
This gives rise to an optimum combination of shaping flexibility,
corrosion resistance and resistance to the action of
temperature.
[0018] The soldering method used is preferably brazing, this in
turn being carried out in particular in a continuous furnace or
vacuum furnace. A solder filler material is used on a nickel-iron
basis. This ensures a high corrosion resistance even in the case of
the solder filler material. The phase equilibrium in the duplex
steels is not altered by the soldering process. Ferrite and
austenite are present in each case in a proportion of 50%. In
particular, a soldering temperature here is between 980.degree. C.
and 1100.degree. C.
[0019] In a further preferred embodiment variant, brackets made of
duplex steel are arranged on the casing. These brackets are then
used to couple the exhaust-gas heat exchanger according to the
invention to an internal combustion engine. The brackets themselves
can be coupled to the casing by integral joining or preferably can
also be formed in a one piece and materially integral form on the
casing. Within the context of the invention, in particular the
components of the casing, of the inner cassette and/or of the fin
plate are then produced as formed sheet metal components, in
particular deep-drawn components.
[0020] Further advantages, features, properties and aspects of the
present invention are the subject matter of the description
hereinbelow. Preferred embodiment variants are shown in the
schematic figures. These serve for the simple understanding of the
invention. In the drawing:
[0021] FIG. 1 shows a longitudinal sectional view through an
exhaust-gas heat exchanger, and
[0022] FIG. 2 shows a cross-sectional view through an exhaust-gas
heat exchanger according to the invention.
[0023] In the figures, the same reference signs are used for the
same or similar components, even if a repeated description has been
omitted for reasons of simplicity.
[0024] FIGS. 1 and 2 show an exhaust-gas heat exchanger 1 in a
longitudinal sectional view and, respectively, in a cross-sectional
view. According to the invention, the exhaust-gas heat exchanger 1
is embodied as a plate heat exchanger, a first flow duct 2 being
formed between the inner lateral surface 3 of an outer casing 4 and
the outer lateral surface 5 of the inner cassettes 6 arranged in
the casing 4. A second flow duct 7 is then formed in the inner
cassettes 6, provision likewise being made of a respective fin
plate 8 to increase the surface area available there for taking up
heat. The exhaust gas A can then flow in the inner cassette 6, a
corresponding quantity of heat being taken up by way of the fin
plate 8 and also the inner lateral surface 9 of the inner cassette
6 and being passed on via the wall of the inner cassette 6 to a
fluid (not shown in greater detail) in the first flow duct 2.
According to the invention, provision is now made of a structure in
such a form that the fin plate 8 is formed from austenitic
material, the inner cassette 6 is formed from ferritic material or
from duplex steel and the casing 4 is formed from duplex steel. The
choice as to whether duplex steel or ferritic steel material is
used for the inner cassette 6 is dependent on the expected
vibrational loading. If relatively low vibrational loading is to be
recorded, a ferritic steel material is used, whereas a duplex steel
is used in the case of high expected vibrational loading.
[0025] Furthermore, the casing 4 is embodied in a two-shell form
and has a first shell 10 and a second shell 11. In turn, brackets
12 are coupled to the outer side of the casing 4 for fastening the
exhaust-gas heat exchanger 1 to an engine (not shown in greater
detail) or an internal combustion engine. The first shell 10 and
the second shell 11 are each of U-shaped configuration in cross
section and are inserted into one another in an opposite direction,
such that an optimum soldering gap 13 is established at a joint in
order to produce a soldered seam with a particularly high quality
in a later soldering method, such that this entails a high
tightness and resistance to vibrations particularly under aspects
of durability. The brackets 12 themselves can be formed in a one
piece and materially integral form on the outer side of the casing
4 or else also can have a multi-part form, such that they are
coupled to the casing 4 by means of a coupling method (not shown in
greater detail). FIGS. 1 and 2 furthermore show spacing bosses 14
between the inner cassettes 6 and also between the outer inner
cassette 6 and the casing 4; these spacing bosses can also be
embodied in the form of a bulge or else a concavity. In particular,
the spacing bosses 14 can be introduced into the respective shell
of the inner cassette 6 or the casing 4 by an embossing operation.
These then serve to form a spacing between the inner cassettes 6,
and this in turn leads to the formation of the respective first
flow duct 2. Furthermore, respectively outwardly flared ends 15,
which taper toward one another, of respectively two mutually
adjacent inner cassettes 6 are shown at the ends of the inner
cassettes 6. These outwardly flared ends 15, too, are soldered to
one another. This produces the tightness at the edge between the
first flow duct 2 and the second flow duct 7. The outwardly flared
ends 15 likewise expand during the soldering operation, and this
leads to a good quality of the soldered connection present
therebetween.
REFERENCE SIGNS
[0026] 1--Exhaust-gas heat exchanger
[0027] 2--First flow duct
[0028] 3--Inner lateral surface of 4
[0029] 4--Casing
[0030] 5--Outer lateral surface of 6
[0031] 6--Inner cassette
[0032] 7--Second flow duct
[0033] 8--Fin plate
[0034] 9--Inner lateral surface of 6
[0035] 10--First shell of 4
[0036] 11--Second shell of 4
[0037] 12--Brackets
[0038] 13--Soldering gap
[0039] 14--Spacing bosses
[0040] 15--End of 6
[0041] A--Exhaust gas
* * * * *