U.S. patent application number 12/066588 was filed with the patent office on 2008-10-09 for heat exchanger, in particular exhaust gas heat exchanger.
This patent application is currently assigned to BEHR GmbH & Co., KG. Invention is credited to Klaus Fischle, Dieter Gross, Oliver Mamber, Matthias Pfitzer.
Application Number | 20080245512 12/066588 |
Document ID | / |
Family ID | 37507708 |
Filed Date | 2008-10-09 |
United States Patent
Application |
20080245512 |
Kind Code |
A1 |
Fischle; Klaus ; et
al. |
October 9, 2008 |
Heat Exchanger, In Particular Exhaust Gas Heat Exchanger
Abstract
The invention relates to a heat exchanger, in particular an
exhaust gas heat exchanger, having at least one surface which is
impinged on by a medium, in particular exhaust gas, is made from
metal, in particular aluminum or stainless steel, and is provided
with a coating. In order to improve the properties of the coating,
according to the invention, the coating comprises a coating
material based on nanotechnology.
Inventors: |
Fischle; Klaus; (Tamm,
DE) ; Gross; Dieter; (Stuttgart, DE) ; Mamber;
Oliver; (Stuttgart, DE) ; Pfitzer; Matthias;
(Deizisau, DE) |
Correspondence
Address: |
FOLEY AND LARDNER LLP;SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
BEHR GmbH & Co., KG
Stuttgart
DE
|
Family ID: |
37507708 |
Appl. No.: |
12/066588 |
Filed: |
September 12, 2006 |
PCT Filed: |
September 12, 2006 |
PCT NO: |
PCT/EP06/08851 |
371 Date: |
May 8, 2008 |
Current U.S.
Class: |
165/133 |
Current CPC
Class: |
F28F 19/06 20130101;
F28F 19/02 20130101 |
Class at
Publication: |
165/133 |
International
Class: |
F28F 19/02 20060101
F28F019/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 14, 2005 |
DE |
10 2005 043 730.3 |
Claims
1. A heat exchanger, in particular an exhaust gas heat exchanger,
having at least one metal surface, in particular an aluminum or
special steel surface, on which a medium, in particular exhaust
gas, impinges and which is provided with a coating, wherein the
coating comprises a coating material, which is based on
nanotechnology.
2. The heat exchanger as claimed in claim 1, wherein the coating
comprises a main constituent, which is composed of an organic and
an inorganic fraction.
3. The heat exchanger as claimed in claim 1 wherein the coating
contains silicon.
4. The heat exchanger as claimed in claim 1, wherein the coating
contains titanium, zirconium and/or aluminum.
5. The heat exchanger as claimed in claim 1 wherein the coating
contains magnesium, zinc and/or calcium.
6. A method of manufacturing a heat exchanger, in particular an
exhaust gas heat exchanger, as claimed in claim 1, wherein the
coating is produced by a sol-gel process.
7. The method as claimed in claim 6, wherein at least one sol is
applied to the surface to be coated.
8. The method as claimed in claim 7, wherein the sol is cured in
order to form a cross-linked polymer layer.
9. The method as claimed in claim 6, characterized by the following
process steps: a) a heat exchanger to be coated is flooded with the
coating material and drained; b) the drained heat exchanger is
heated in a drying oven and/or has a flow of hot gas, in particular
hot air, passed through it.
Description
[0001] The invention relates to a heat exchanger, in particular an
exhaust gas heat exchanger, having at least one metal surface, in
particular an aluminum or special steel surface, on which a medium,
in particular exhaust gas, impinges and which is provided with a
coating. The invention also relates to a method of manufacturing a
heat exchanger as described above.
[0002] In exhaust gas heat exchangers, exhaust gas, predominantly
from diesel engines, together with moisture and heat, leads to
corrosion attacks on the metals used. Heat-resistant paints may be
used to protect against corrosion.
[0003] The object of the invention is to create a heat exchanger,
in particular an exhaust gas heat exchanger, having at least one
metal surface, in particular an aluminum or special steel surface,
on which a medium, in particular exhaust gas, impinges and which is
provided with a coating, said coating possessing better
characteristics than conventional paints, and manufacture of the
heat exchanger being reliable.
[0004] In a heat exchanger, in particular an exhaust gas heat
exchanger, having at least one metal surface, in particular an
aluminum or special steel surface, on which a medium, in particular
exhaust gas, impinges and which is provided with a coating, the
object is achieved in that the coating comprises a coating
material, which is based on nanotechnology. The coating material
preferably comprises at least one nanomaterial or nanostructure.
The coating is vitreous and possesses a very good chemical
resistance.
[0005] A preferred exemplary embodiment of the heat exchanger is
characterized in that the coating comprises a main constituent,
which is composed of an organic and an inorganic fraction. It is
possible, by way of the cross-linking temperature, to define and to
vary the characteristics of the coating within wide limits.
[0006] A further preferred exemplary embodiment of the heat
exchanger is characterized in that the coating contains silicon.
Organo(alkoxy)silanes are preferably purposely hydrolyzed by the
use of suitable catalysts, eliminating alcohols.
[0007] Further preferred exemplary embodiments of the heat
exchanger are characterized in that the coating contains titanium,
zirconium, aluminum, magnesium, zinc and/or calcium. The inorganic
network can be purposely modified by the various substances.
[0008] In a method of manufacturing a heat exchanger as described
above, in particular an exhaust gas heat exchanger, the aforesaid
object is achieved in that the coating is produced by a sol-gel
process. In the sol-gel process a sol is converted into a gel to
produce nano-materials. Through hydrolysis and condensation
reactions a three-dimensional network of interlayered molecules is
produced in a liquid. Thermal processing stages serve to process
the gels further into nano-materials or nanostructures.
[0009] A preferred exemplary embodiment of the method is
characterized in that at least one sol is applied to the surface to
be coated. The surface to be coated may be wetted with the sol in
any suitable way.
[0010] A further preferred exemplary embodiment of the method is
characterized in that the sol is cured. The curing is preferably
performed under the effect of heat.
[0011] A further preferred exemplary embodiment of the method is
characterized by the following process steps: a heat exchanger to
be coated is flooded with the coating material and drained; the
drained heat exchanger is heated in a drying oven. The heat
exchanger to be coated is force-flooded by the coating substance
and then drained. The heat exchanger is then preferably suspended
so that all excess coating substance can run off without unwanted
accumulations of coating substance being formed inside the heat
exchanger. Drops adhering to the outlet from the heat exchanger are
suitably removed, for example by means of compressed air or with
the aid of an electrostatic droplet extractor.
[0012] Further advantages, features and details of the invention
are set forth in the following description, in which various
exemplary embodiments are described in detail. The features
mentioned in the claims and in the description may here each be
essential for the invention either individually or in any
combination.
[0013] The invention relates to an exhaust gas heat exchanger made
from aluminum or special steel. The exhaust gas heat exchanger has
a cavity, through which exhaust gas flows when the exhaust gas heat
exchanger is in operation. The cavity is coated with a
nanotechnology-based coating substance. The main constituent of the
coating substance is composed of an organic and an inorganic
fraction. It is possible, by way of the cross-linking temperature,
to define the characteristics of the coating within wide limits. At
high stoving temperatures a higher proportion of the organic
contents is expelled, that is to say there is a greater degree of
crosslinking. The corrosion resistance of the coating is thereby
improved. At low stoving temperatures the proportion of organic
contents is greater, that is to say the ductility of the coating
becomes greater.
[0014] According to one aspect of the present invention an exhaust
gas heat exchanger to be coated is force-flooded with the coating
substance and then drained. The heat exchanger is then suspended so
that all excess coating substance can run off without forming
unwanted accumulations in the interior. Drops adhering to the
outlet are suitably removed, for example by means of compressed air
or with the aid of an electrostatic droplet extractor. The exhaust
gas heat exchanger then runs through a drying oven.
[0015] The coating is here produced by a sol-gel process, for
example by so-called ORMOCER layers. The term ORMOCER relates to a
trademark of the Fraunhofer Gesellschaft for the advancement of
applied research in Munich. To produce layers,
organo(alkoxyl)silanes are purposely hydrolyzed through the use of
suitable catalysts for the elimination of alcohols, such as
methanol, ethanol, etc. Subsequent condensation reactions lead to
the formation of organically modified inorganic-oxidic structures.
For modification of the inorganic network, silicon can also be
partially replaced by other elements, especially titanium,
zirconium or aluminum. In addition the elements magnesium, zinc and
calcium can be incorporated. The aqueous-alcoholic sols are applied
to the heat exchanger to be coated in the flooding process, and
heat-cured. In this way a cross-linked polymer layer is
produced.
[0016] The purpose of the coating, in addition to the anticorrosive
and/or water-repellent characteristic, is also at the same time to
prevent dirt, particles, soot and oil films from adhering. When
using ORMOCER layers this oleophobic effect can be achieved by a
fraction of 0.1 to 10%, preferably 0.5 to 5% and in particular by 1
to 2% of fluorosilanes in the ORMOCER layer. The incorporation of a
layer of simultaneously hydrophobic and oleophobic nature is
achieved by the addition of an alkoxysilane with highly fluorinated
alkyl chains. Particularly beneficial effects are achieved here by
silanes of the F13(CF.sub.3--(CF.sub.2).sub.5--) and
F16(CF.sub.2H--(CF.sub.2).sub.7--) type.
* * * * *