U.S. patent application number 11/540328 was filed with the patent office on 2007-02-01 for metallic honeycomb structure.
This patent application is currently assigned to Emitec Gesellschaft fur Emissionstechnologie mbh. Invention is credited to Ferdi Kurth, Jurgen Peters, Michael Voit, Ludwig Wieres.
Application Number | 20070026252 11/540328 |
Document ID | / |
Family ID | 33521098 |
Filed Date | 2007-02-01 |
United States Patent
Application |
20070026252 |
Kind Code |
A1 |
Voit; Michael ; et
al. |
February 1, 2007 |
Metallic honeycomb structure
Abstract
A honeycomb structure includes a plurality of substantially
parallel channels, a layer of at least partially structured metal
foils and a housing. The layer includes a number N of at least
partially structured metal foils and a number N+1 of smooth metal
foils. The number N=1, 2 or 3 and two of the smooth metal foils are
exterior foils. A method for producing such a honeycomb structure
is also provided. The honeycomb structure is used, in particular in
exhaust gas systems of mobile internal combustion engines.
Inventors: |
Voit; Michael; (Leverkusen,
DE) ; Peters; Jurgen; (St. Augustin, DE) ;
Kurth; Ferdi; (Mechernich, DE) ; Wieres; Ludwig;
(Overath, DE) |
Correspondence
Address: |
LERNER GREENBERG STEMER LLP
P O BOX 2480
HOLLYWOOD
FL
33022-2480
US
|
Assignee: |
Emitec Gesellschaft fur
Emissionstechnologie mbh
|
Family ID: |
33521098 |
Appl. No.: |
11/540328 |
Filed: |
September 29, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11318898 |
Dec 27, 2005 |
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11540328 |
Sep 29, 2006 |
|
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PCT/EP04/06203 |
Jun 9, 2004 |
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11318898 |
Dec 27, 2005 |
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Current U.S.
Class: |
428/593 |
Current CPC
Class: |
B23K 1/0014 20130101;
Y10T 29/49345 20150115; F01N 2330/32 20130101; Y10T 29/49826
20150115; Y10T 29/49908 20150115; F01N 2450/02 20130101; B23K
2101/02 20180801; F01N 2330/02 20130101; F01N 3/2842 20130101; Y10T
428/1234 20150115; F01N 2330/44 20130101; F01N 3/281 20130101 |
Class at
Publication: |
428/593 |
International
Class: |
B32B 3/12 20060101
B32B003/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 27, 2003 |
DE |
103 29 002.8 |
Claims
1. A honeycomb structure, comprising: a housing; a multiplicity of
passages disposed substantially parallel to one another within said
housing; and a layer of at least partially structured sheet-metal
foils defining said passages, said layer having a length of less
than 500 mm, a number N of at least partially structured
sheet-metal foils, and a number N+1 of smooth sheet-metal foils,
said number N being 1, 2 or 3, and two of said smooth sheet-metal
foils being outer sheet-metal foils; said passages defining a flow
direction, the honeycomb structure having a mean extent of less
than 50 mm perpendicular to said flow direction of said
passages.
2. The honeycomb structure according to claim 1, wherein said layer
is at least one of wound or twisted, causing outer smooth
sheet-metal foils to be directly adjacent one another at least in a
subsection of said layer.
3. The honeycomb structure according to claim 1, wherein a further
smooth sheet-metal foil and a structured sheet-metal foil are
disposed alternately between said outer smooth sheet-metal foils in
said layer.
4. The honeycomb structure according to claim 3, wherein a
structured sheet-metal foil is disposed adjacent said outer smooth
sheet-metal foils in each case.
5. The honeycomb structure according to claim 1, wherein said
sheet-metal foils of said layer each have two ends, and at least
90% of said ends are connected to said housing, at least in a
sector of said housing.
6. The honeycomb structure according to claim 1, wherein said
sheet-metal foils of said layer each have two ends, and all of said
ends are connected to said housing, at least in a sector of said
housing.
7. The honeycomb structure according to claim 1, which further
comprises at least one sleeve disposed between said housing and
said sheet-metal foils, said sheet-metal foils of said layer each
having two ends, and at least 90% of said ends being connected to
said at least one sleeve at least in one zone of said at least one
sleeve.
8. The honeycomb structure according to claim 1, which further
comprises at least one sleeve disposed between said housing and
said sheet-metal foils, said sheet-metal foils of said layer each
having two ends, and all of said ends being connected to said at
least one sleeve at least in one zone of said at least one
sleeve.
9. The honeycomb structure according to claim 1, wherein said
passages define a flow direction, and the honeycomb structure has a
mean extent of from 20 mm to 30 mm perpendicular to said flow
direction of said passages.
10. The honeycomb structure according to claim 1, wherein said
layer has a length of from 100 mm to 300 mm.
Description
CROSS-REFERENCE TO THE RELATED APPLICATION
[0001] This is a division of U.S. application Ser. No. 11/318,898,
filed Dec. 27, 2005, which was a continuation of copending
International Application No. PCT/EP 2004/006203, filed Jun. 9,
2004, which designated the United States; this application also
claims the priority, under 35 U.S.C. .sctn.119, of German Patent
Application 103 29 002.8, filed Jun. 27, 2003; the prior
applications are herewith incorporated by reference in their
entirety.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] The invention relates to a honeycomb structure having a
multiplicity of passages disposed substantially parallel to one
another, at least one layer of at least partially structured
sheet-metal foils and a housing. Honeycomb structures of this type
are preferably used as a component for treating exhaust gases from
mobile internal combustion engines.
[0003] Exhaust-gas purification components in exhaust systems of
mobile internal combustion engines (such as for example
spark-ignition or diesel engines) in motor vehicles, lawn mowers,
chain saws, motorcycles, etc., generally have the object of
converting or storing (at least for a certain period of time)
pollutants contained in the exhaust gas. Known examples of
exhaust-gas components of that type include catalytic converters,
filters, absorbers or separators. The honeycomb structure provides
a very large surface area which can come into contact with the
exhaust gas flowing through it or past it. The resulting intimate
contact with the exhaust gas leads to a high efficiency on the part
of the exhaust-gas purification component.
[0004] Honeycomb structures of that type made from ceramic or
metallic materials are fundamentally known. The person skilled in
the art is aware of a large number of different manufacturing
processes for producing such honeycomb bodies, in particular
extrusion or the connection by technical joining of partial
components, such as metal sheets, fibrous layers, grid structures
or the like. The preferred manner of producing the technical
joining connection is by brazing. However, a sintering process or
even welding may be used as well. Due to the fact that exhaust-gas
purification components of that type are always matched to the
requirements (e.g. with regard to type or construction) of the
internal combustion engine, it is desirable for it to be possible
for a large number of different variants of honeycomb structures of
that type to be produced in simple manufacturing processes. In the
past, it has been found that metallic honeycomb bodies which are
constructed, for example, from at least partially structured
sheet-metal foils can be realized with a much greater range of
variety without excessive modifications to the manufacturing
process being required.
[0005] There are numerous known different construction options and
production processes with regard to metallic honeycomb structures
of that type. A distinction is drawn in particular between two
typical constructions. An early construction, of which German
Published, Non-Prosecuted Patent Application DE 29 02 779 A1,
corresponding to U.S. Pat. No. 4,273,681, shows typical examples,
is the helical construction, in which substantially one smooth and
one corrugated sheet-metal layer are placed on top of one another
and wound helically. In another construction, the honeycomb body is
constructed from a multiplicity of alternately disposed smooth and
corrugated or differently corrugated sheet-metal layers, the
sheet-metal layers initially forming one or more stacks which are
then intertwined. In that case, the ends of all of the sheet-metal
layers come to lie on the outside and can be connected to a housing
or tubular casing, producing numerous connections, which increase
the durability of the honeycomb body. Typical examples of those
constructions are described in European Patent EP 0 245 737 B1,
corresponding to U.S. Pat. Nos. 4,946,822; 4,923,109; 4,832,998 and
4,803,189, or International Publication No. WO 90/03220,
corresponding to U.S. Pat. Nos. 5,139,844; 5,135,794 and 5,105,539.
It has also long been known to equip the sheet-metal layers with
additional structures in order to influence the flow and/or bring
about cross-mixing between the individual flow passages. Typical
examples of those configurations include International Publication
No. WO 91/01178, corresponding to U.S. Pat. No. 5,403,559,
International Publication No. WO 91/01807, corresponding to U.S.
Pat. Nos. 5,130,208 and 5,045,403, and International Publication
No. WO 90/08249, corresponding to U.S. Pat. No. 5,157,010. Finally,
there are also conical honeycomb bodies, optionally also with
further additional structures for influencing the flow. A honeycomb
body of that type is described, for example, in International
Publication No. WO 97/49905, corresponding to U.S. Pat. No.
6,190,784. Furthermore, it is also known to leave free a cutout in
a honeycomb body for a sensor, in particular for accommodating a
lambda sensor. One such example is described in German Utility
Model DE 88 16 154 U1. With regard to the production of honeycomb
structures of that type, reference is made in particular to the
following publications: International Publication No. WO 98/34725,
corresponding to U.S. Pat. Nos. 6,571,458 and 6,226,867 and U.S.
Patent Application Publication No. US 2001/0009064, International
Publication No. WO 97/06358, corresponding to U.S. Pat. Nos.
6,311,395 and 6,049,980, International Publication No. WO 97/00725,
corresponding to U.S. Pat. Nos. 6,115,906 and 6,029,488, and
International Publication No. WO 97/00135, corresponding to U.S.
Pat. Nos. 6,505,396 and 6,049,961.
[0006] With regard to the publications cited, structured and smooth
sheet-metal foils are generally stacked alternately on top of one
another and then wound and/or twisted in such a way that they
assume an external configuration which substantially corresponds to
the shape of the housing into which they are subsequently inserted.
Under certain circumstances, those structured and smooth
sheet-metal foils are disposed in stacks and/or layers, with the
same number of smooth and structured sheet-metal foils being
provided in each case. The sheet-metal foils which bear against one
another in that way then form passages on each of the two sides,
and the exhaust gas can flow through those passages.
[0007] In particular, in the case of honeycomb structures which are
formed by using relatively short sheet-metal foils, technical
problems may arise with the formation of connections by technical
joining. For example, if the honeycomb structure has a maximum
extent of less than 30 mm (in which case the sheet-metal foils are
not wound helically), the situation may arise whereby contact
regions occur within and/or between structured sheet-metal foils.
That problem exists in particular if the layers are wrapped in an
S-shape or in a similar way. The result thereof is that the
structures engage inside one another and consequently at least some
passages are malformed. That increases the risk of the passages
becoming blocked, or at least of different coating thicknesses
being produced, during subsequent coating of the honeycomb
structure. That can lead, for example, to an increase in the flow
resistance of the honeycomb structure at least in subregions. That
can in turn give rise to different thermal stresses, lower
conversion rates or even a reduction in the power of the upstream
internal combustion engine. A further risk is that subsections
which are inaccessible to the application of additional materials
for forming connections by technical joining, such as for example
brazing material, will be formed. Those subregions, which are
subsequently not connected or not completely connected, can lead to
the component being destroyed due to the extremely high thermal and
dynamic loads which occur in the exhaust system.
SUMMARY OF THE INVENTION
[0008] It is accordingly an object of the invention to provide a
metallic honeycomb structure and a process for producing the same,
which overcome the hereinafore-mentioned disadvantages of the
heretofore-known products and processes of this general type, which
provide a honeycomb structure that has a simple construction, can
be produced with a low outlay in terms of manufacturing technology,
has a uniform formation of passages through which the exhaust gas
can flow and has a reliable attachment of adjacent sheet-metal
foils to one another and to the housing, and in which the process
allows the production of a honeycomb structure, in particular with
small dimensions, in a reliable way.
[0009] With the foregoing and other objects in view there is
provided, in accordance with the invention, a honeycomb structure,
comprising a housing, a multiplicity of passages disposed
substantially parallel to one another within the housing, and a
layer of at least partially structured sheet-metal foils defining
the passages. The layer has a number N is of at least partially
structured sheet-metal foils, a number N+1 of smooth sheet-metal
foils, the number N is 1, 2 or 3, and two of the smooth sheet-metal
foils are outer sheet-metal foils.
[0010] In other words, this means in particular that the layer
forms a type of sandwich in which the two outer sheet-metal foils
are smooth. A sheet-metal foil is to be understood as being
"smooth" in particular if it does not have any corrugations,
stamped formations, folds, etc. However, this does not necessarily
mean that the smooth sheet-metal foil has a specific (for example
particularly low) surface roughness or that it is not, for example,
wound in an S-shape or in a similar way. At least one, at least
partially "structured" sheet-metal foil is disposed between the two
outer, smooth sheet-metal foils.
[0011] It is fundamentally also possible for a plurality of
sheet-metal foils to be disposed between the two outer smooth
sheet-metal foils and to form the layer, in which case at least one
of these additional sheet-metal foils is at least partially
structured. By way of example, it is also practicable for a stack
of a plurality of alternately disposed smooth and structured
sheet-metal foils to be provided between the two outer smooth
sheet-metal foils. Furthermore, it is conceivable for a sheet-metal
foil, by way of example, to be only partially structured while at
the same time also having smooth sections. In this case, the
(smooth and) structured sheet-metal foils disposed in the interior
at least partially form passage walls on both sides (i.e. on the
large-area surfaces). By contrast, the configuration of the at
least one layer to form a honeycomb structure is such that the
outer smooth sheet-metal foils form passages only toward one side,
namely toward the internally disposed, at least one at least
partially structured sheet-metal foil. Toward the outside, these
outer smooth sheet-metal foils preferably at least partially bear
against themselves and/or against adjacent outer smooth sheet-metal
foils and/or against the housing. These smooth sheet-metal foils
nestle against one another in such a way that no passages through
which the exhaust gas can flow are formed.
[0012] The provision of two outer smooth sheet-metal foils ensures
that direct contact between sections of the structured sheet-metal
foils disposed adjacent one another is avoided. This leads to a
reduction in defects with regard to the construction of the
honeycomb structure, so that a uniform distribution of the passages
over the cross section of the honeycomb structure is ensured. The
outer smooth sheet-metal foils bearing directly against one another
also means that during a heat treatment of the honeycomb structure,
for example as part of a brazing process, connections by technical
joining are formed between these smooth sheet-metal foils. These
connections have their origin primarily in diffusion phenomena,
which lead to local diffusion welds. This ensures permanent
connection of the layers to one another and/or the outer smooth
sheet-metal foils disposed adjacent one another.
[0013] This also avoids the "telescoping" phenomenon, whereby
adjacent layers move relative to one another due to the loads which
occur in the exhaust system. Depending on the pressure with which
the outer smooth sheet-metal foils disposed adjacent one another
are pressed against one another and/or are introduced into the
housing before the heat treatment, diffusion bonds of this type may
form over the entire contact surface. If (in particular with regard
to the thermal expansion properties of honeycomb bodies of this
type) it is intended to prevent a complete join from being formed,
it is possible for a substance which suppresses the formation in
particular of diffusion bonds to be provided on the (smooth and/or
structured) sheet-metal foils. By way of example, special coatings,
such as titanium oxide, aluminum oxide, etc., are recommended for
this purpose. However, passivation layers of this type may be
disposed not only between the outer smooth sheet-metal foils but
also, for example, between the smooth sheet-metal foils and the
housing.
[0014] In accordance with another feature of the invention, the
layer is wound and/or twisted to form the honeycomb body, in such a
way that, at least in a subsection of the layer, outer smooth
sheet-metal foils are disposed directly adjacent one another. This
means in particular that there is a particularly high degree of
bending or wrapping of the layer. Such extreme profiles, at which
the smooth sheet-metal foils are constructed to bear against
themselves, occur in particular in honeycomb bodies with a
polygonal outer configuration, i.e. a configuration which differs
from a cylindrical shape.
[0015] In particular, in order to reach even the corner regions of
this polygonal outer configuration, it is necessary for there to be
particularly tightly wound subsections which penetrate all the way
into these corner regions. This is also to be understood as meaning
in particular profiles in which the at least one layer is bent in a
meandering form, i.e. is alternately bent in one direction and then
another (opposite) direction (if appropriate with different radii
of curvature). Due to these extreme deformations, there was always
a risk of the sheet-metal foils of known honeycomb structures not
being formed in a desired way, in particular because the known
sheet-metal foil stacks had to be positioned in a complex way with
respect to one another when planning production and then connected
to one another by technical joining. This technical problem is
eliminated by the provision of outer smooth sheet-metal foils.
[0016] In accordance with a further feature of the invention, a
further smooth sheet-metal foil and a structured sheet-metal foil
are disposed alternately between the outer smooth sheet-metal foils
in the layer. Preferably, in each case, a structured sheet-metal
foil is disposed adjacent the outer smooth sheet-metal foils. This
is to be understood in particular as meaning a sandwich structure
which is distinguished by two externally disposed, smooth
sheet-metal foils and a plurality of inner sheet-metal foils. With
regard to the inner sheet-metal foils, an alternating configuration
of further smooth sheet-metal foils and structured sheet-metal
foils is now proposed. These internally disposed, smooth and
structured sheet-metal foils delimit passages through which the
exhaust gas can flow on each of their two sides. This substantially
symmetrical construction with alternating smooth and structured
sheet-metal foils ensures the production of defined connections
between smooth and structured sheet-metal foils in the vicinity of
the extremities of the structured sheet-metal foils, in particular
the corrugation peaks or corrugation valleys.
[0017] In accordance with an added feature of the invention, the
sheet-metal foils of the layers each have two ends, at least 90% of
these ends being connected to the housing at least in a sector, and
preferably all of the ends being connected to the housing. It is
clear from this in particular that the honeycomb structure has a
configuration which deviates from a helical construction. If the
layers are wound up helically, it is usual for half of all of the
ends to be disposed in the center of the honeycomb structure, while
the opposite ends of the layers or sheet-metal foils bear against
the housing. In the particularly preferred configuration of the
honeycomb structure described herein, the sheet-metal foils or
sheet-metal layers are disposed in such a way that, starting from
the housing, they extend into an inner region of the honeycomb
structure, before ultimately coming to bear against the inner
surface of the housing again by way of the opposite end.
[0018] The fact that these ends are connected or in contact at
least in a sector takes into account the fact that, for example,
the housing is constructed to be larger or smaller, and therefore
not all of the inner surface of the housing necessarily has to be
in contact with the sheet-metal foils. However (for example in the
case of an S-shaped configuration of the layers), it is also
possible for the ends of the layers not to be disposed uniformly
over the circumference of the housing or the honeycomb structure,
but rather for there to be partial circumferential sections in
which all or some of the ends are disposed, with an outer smooth
sheet-metal foil nestling against the inner side of the housing
between them.
[0019] It is preferable to use technical joining techniques to
connect the ends to the housing, i.e. the ends are brazed or welded
to the housing. The percentage of the ends connected to the housing
which is mentioned is to be understood in particular as meaning
that the next highest integer number of ends is connected to the
housing. For example, if the honeycomb structure is formed from 2
sheet-metal layers (as can be produced by using the process
described below) which each include 2 smooth and 1 structured
sheet-metal foil, the layers have a total of 12 ends. The statement
that at least 90% of these ends are connected to the housing is in
this context to be understood as meaning that at least 11 of these
ends are connected to the housing (12.times.0.9=10.8=>next
highest integer number of ends is 11).
[0020] In accordance with an additional feature of the invention,
at least one sleeve is provided between the housing and the
sheet-metal foils, the sheet-metal foils of the layer each have two
ends, at least 90% of these ends are connected to the at least one
sleeve at least in one zone, and preferably all of the ends are
connected to the at least one sleeve. In principle, for
explanation, reference is substantially made to the preceding
paragraph. A significant difference between these two
configurations is that in this case a sleeve is provided between
the sheet-metal foils and the housing. This sleeve has the purpose
of compensating for the different thermal expansion properties of
the sheet-metal foils with respect to the housing. The housing,
which is intended primarily to ensure the structural integrity of
the honeycomb structure, has to be made relatively stable, for
example using housing wall thicknesses of from 1 mm to 3 mm. By
contrast, to realize a low area-specific heat capacity and to
provide the largest possible surface area, the sheet-metal foils
are used in very thin thicknesses, in particular with a sheet-metal
thickness of less than 0.1 mm, most preferably even less than 0.03
mm. Due to the different area-specific heat capacities, a rigid
connection between the sheet metal foils and the housing would
entail the risk of the sheet-metal foils tearing or connections
becoming detached. In order to avoid this, a sleeve which permits
relative movements of the sheet-metal foils with respect to the
housing is provided between the sheet-metal foils and the housing.
With regard to the construction of sleeves of this type, reference
is also made to International Publication No. WO 03/008774,
corresponding to U.S. Patent Application Publication No. US
2004/0152594, the content of the disclosure of which is hereby also
incorporated and referred to in full.
[0021] In accordance with yet another feature of the invention, the
honeycomb structure has a mean extent perpendicularly to the
profile of the passages which is less than 50 mm, in particular in
a range from 20 mm to 30 mm. These relatively small honeycomb
structures are a particular field of use for the layered
construction with two outer smooth sheet-metal foils. One reason
for this is that this relatively short layer is difficult to handle
during production if an outer sheet-metal foil is structured. This
layer in some cases has to be considerably deformed, during which
the structured sheet-metal foil under certain circumstances may
become wedged against itself or foils disposed adjacent it.
Accordingly, a considerably improved, reliable execution of the
production process in particular in the case of relatively small
honeycomb structures is possible.
[0022] In accordance with yet a further feature of the invention,
the layer has a length which is less than 500 mm, in particular in
a range from 100 mm to 300 mm. The lengths of the sheet-metal
layers mentioned herein differ considerably from those which were
already known, where the ratio of the length of the layer being
used to the diameter of the support is considerably greater. For
example, a known honeycomb body with a diameter of, for example, 10
cm has a layer length which is greater by at least a factor of 20.
Here, a ratio which is considerably smaller is preferably proposed,
in particular less than 10 or even less than 8.
[0023] With the objects of the invention in view, there is also
provided a process for producing a honeycomb structure. The process
comprises forming at least one layer having at least one at least
partially structured sheet-metal foil disposed between two outer
smooth sheet-metal foils. The at least one layer is wound to form a
multiplicity of passages disposed substantially parallel to one
another. The at least one wound layer is introduced into a
housing.
[0024] In this case it is preferable to form the at least one layer
in such a way that a smooth sheet-metal foil, a completely
structured sheet-metal foil and another smooth sheet-metal foil are
disposed alternately on top of one another. However, it is also
possible for the two outer smooth sheet-metal layers to be
connected to one another or for a continuous smooth sheet-metal
strip to be provided, for example forming a U-shaped envelope, in
which case a structured sheet-metal foil is disposed therein. If a
plurality of layers are used to construct the honeycomb structure,
once again the outer smooth sheet-metal foil of one layer has an
outer smooth sheet-metal foil of the adjacent layer disposed on it,
etc. The plurality of layers can form a stack, which in principle
is in turn delimited by smooth sheet-metal foils. With regard to
the honeycomb structure which can be produced, reference is in
principle made to the statements given above. It is also possible
through the use of this process to produce honeycomb structures
having a plurality of layers, for example having 2 to 5 layers.
[0025] The process step of "winding" is to be understood as meaning
bending over, folding over, kinking and/or winding up the at least
one layer. In this context, the at least one layer then has an
outer shape or lateral surface which substantially corresponds to
the configuration of the housing. It is preferable for the wound
layer or the wound layer package to have a cross section which is
slightly larger than the cross section enclosed by the housing.
This produces a prestress ensuring that the ends of the sheet-metal
layers bear flush against the inner surface of the housing. The
area-based difference or the prestress in this case amounts to
approximately on the order of magnitude of 2% to 5%.
[0026] Finally, the layer which has been wound in this way is at
least partially introduced into a housing. Partial introduction of
the at least one wound layer opens up the possibility of providing
the outer, exposed ends of the at least one layer with additional
materials, such as strips of brazing material, etc. Then, the at
least one layer which has been prepared in this way can be
positioned entirely within the housing at the desired position.
[0027] In accordance with another mode of the invention, 2 to 5
layers are formed, wound together and introduced into a
housing.
[0028] In accordance with a further mode of the invention, the at
least one layer is wound according to one of the following
profiles: helical, S-shaped, M-shaped, W-shaped, Z-shaped,
U-shaped, V-shaped, and meandering. The individual profiles are
explained in more detail below with reference to the figures. These
profiles can usually be recognized when the honeycomb structure is
viewed end-on, i.e. in the direction of the passages. In
particular, the smooth sheet-metal foils reveal a profile of this
type.
[0029] In accordance with an added mode of the invention, the at
least one layer of sheet-metal foils is formed in such a manner
that further smooth and structured sheet-metal foils are disposed
alternately between the outer smooth sheet-metal foils. Preferably,
in each case a structured sheet-metal foil is disposed adjacent the
outer smooth sheet-metal foils. With this type of configuration of
the sheet-metal foils, the sheet-metal foils disposed between the
outer smooth sheet-metal foils at least partially delimit passages
on both sides, while the outer smooth sheet-metal foils delimit
passages through which a fluid can flow only on one side. The other
side of the outer smooth sheet-metal foils is required to bear
against adjacent smooth sheet-metal foils, a sleeve or the
housing.
[0030] In accordance with an additional mode of the invention, the
winding is carried out by using a shaping tool which has at least
two shaping jaws and at least one winding pin. The at least one
layer is fed to the shaping tool in such a way that the at least
one winding pin is positioned preferably approximately centrally
with respect to the at least one layer and is in contact with the
at least one layer. Then, the at least one winding pin is rotated
until all of the ends of the sheet-metal foils of the at least one
layer bear against at least one inner side of the shaping jaws. In
this way it is possible to produce in particular S-shaped profiles
of the layers quickly and reliably.
[0031] This process step is explained in more detail below with
reference to the figures. At this point, it should also be noted
that the shaping jaws are formed in such a way that they at least
partially enclose substantially an outer shape which corresponds to
the final outer configuration of the sheet-metal layers when they
are to be inserted in the housing. The approximately central
configuration of the winding pin means that during rotation both
ends of the layer are turned simultaneously, and consequently the
winding or twisting process can be carried out more quickly than,
for example, in the case of helical winding of the layers with the
winding pin disposed in the vicinity of one end of the layers or
sheet-metal foils.
[0032] In accordance with yet another mode of the invention, the at
least one layer, before being wound, is cut to a defined length.
This length is less than 500 mm, and in particular in a range of
from 100 mm to 300 mm. The length proposed herein is used in
particular for honeycomb bodies having a small extent. It is
preferable for all of the layers or sheet-metal layers which are
used to produce the honeycomb structure to have the same
length.
[0033] In accordance with yet a further mode of the invention, the
at least one layer, prior to the cutting operation, is positioned
in a shaping tool for the winding operation, i.e. in other words
the sheet-metal layer is first of all introduced into the shaping
tool and held or fixed by it. This has the advantage that the at
least one layer no longer has to be transported after the cutting
operation, but rather is already in the appropriate position for
the winding process to be carried out. This in turn leads to a
considerable time saving with regard to manufacture and also
reduced handling costs.
[0034] In accordance with yet an added mode of the invention,
before the at least one wound layer is introduced into the housing,
at least one sleeve is positioned around the at least one layer
and/or on an inner surface of the housing. In this case, it is
preferable for the sleeve to be positioned in such a way that it is
disposed substantially centrally with respect to the axial extent
of the layer or the sheet-metal foils. Provisional fixing of the
sleeve to the periphery of the wound layer or to the inner surface
of the housing can be effected by auxiliary substances, such as
adhesives, etc.
[0035] In accordance with a concomitant mode of the invention,
after the at least one layer has been introduced into the housing,
connections are formed by technical joining between the components
of the honeycomb structure, with these components preferably being
brazed to one another at least in subregions. If a sleeve is
disposed between the at least one layer and the housing, this
sleeve has relatively small connecting sections facing the housing,
whereas it is preferably brazed to the at least one layer over the
entire inner side.
[0036] Other features which are considered as characteristic for
the invention are set forth in the appended claims.
[0037] Although the invention is illustrated and described herein
as embodied in a metallic honeycomb structure and a process for
producing the same, it is nevertheless not intended to be limited
to the details shown, since various modifications and structural
changes may be made therein without departing from the spirit of
the invention and within the scope and range of equivalents of the
claims, the features of which also lead to advantageous
configurations in any desired combination with one another.
[0038] The construction and method of operation of the invention,
however, together with additional objects and advantages thereof
will be best understood from the following description of specific
embodiments when read in connection with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] FIG. 1 is a fragmentary, diagrammatic, side-elevational view
illustrating a process for the production of an exemplary
embodiment of a honeycomb body according to the invention;
[0040] FIG. 2 is a partly broken-away, longitudinal-sectional view
of an exemplary embodiment of a honeycomb structure according to
the invention;
[0041] FIG. 3 is a partly broken-away, end-elevational view of an
exemplary embodiment of the honeycomb structure which can be
produced by the process according to the invention;
[0042] FIG. 4 is an elevational view illustrating the construction
of known honeycomb structures in accordance with the prior art;
and
[0043] FIGS. 5A-5F are end-elevational views illustrating various
profiles of different exemplary embodiments of the honeycomb
structure according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0044] Referring now to the figures of the drawings in detail and
first, particularly, to FIG. 1 thereof, there is seen a
diagrammatic illustration of a process for producing a honeycomb
structure having at least one layer 3 of at least partially
structured sheet-metal foils or sheets 4, 5. A honeycomb structure
1 having a multiplicity of passages 2 disposed substantially
parallel to one another and a housing 6, is seen in FIGS. 2 and
3.
[0045] As can be seen from the right-hand side of FIG. 1, the
sheet-metal foils 4, 5 are unwound from coils 25. The sheet-metal
foil 5 is fed to a structuring apparatus 24. The structure of the
structured sheet-metal foil 5 is introduced into a previously
smooth sheet-metal strip in the structuring apparatus 24. The
smooth sheet-metal foils 4 from the upper and lower coils 25 are
disposed on either side of the structured sheet-metal foil 5, with
the metal sheets being passed through two rollers 23. This
operation leads to the formation of a layer 3 which includes two
outer smooth sheet-metal foils 4, between which at least one at
least partially structured sheet-metal foil 5 is disposed. The
rollers 23 are responsible for advancing the sheet-metal foils 4, 5
toward a shaping tool 14. With regard to the feeding of the
sheet-metal foils 4, 5 toward the shaping tool 14, it is preferable
for each sheet-metal foil 4, 5 to be unwound from a separate coil
25 and passed through between the rollers 23. In other words,
during the production of a layer 3 which includes a number (x) of
structured sheet-metal foils 5 and a number (x+1) of smooth
sheet-metal foils 4, in total a number (2x+1) of coils 25 are
provided and simultaneously and optionally continuously feed the
sheet-metal foils 4, 5 to the shaping tool 14.
[0046] The shaping tool 14 has a holder 21 which orients the
sheet-metal layer 3 with respect to the shaping tool 14. The layer
3 is oriented in such a way with respect to winding pins 16 or
shaping jaws 15 that it can then be wound during a simple winding
process. The shaping jaws 15 in this case are open and the layer 3
extends through the shaping jaws 15.
[0047] A cutting apparatus 22 is provided on the opposite side of
the shaping jaws 15 from the holder 21 and positioned in such a way
that the sheet-metal foils 4, 5 can be cut to a predetermined
length 18. During the cutting process, the winding pins 16 are
preferably brought into contact with the layer 3, so as to form a
further holding point. After the sheet-metal foils 4, 5 have been
severed, the shaping tool 14 which is illustrated herein as having
a type of turntable, effects a further displacement, so that the
stacked sheet-metal foils 4, 5 can be fed into the next holder 21
or next shaping jaws 15.
[0048] A layer 3 which has already been cut to length is shown in
the section of the shaping tool 14 illustrated at the upper left.
The winding pins 16 are now in contact with the outer smooth
sheet-metal foils 4. As is indicated by arrows, the layer 3 is then
rotated in such a way that all ends 8 of the sheet-metal foils 4, 5
bear against an inner surface 17 of the shaping jaws 15. For this
purpose, the shaping jaws 15 can also be moved toward one another,
so that they ultimately completely enclose the layer 3. The final
bent layer 3 is then removed from the shaping jaws 15 and
integrated in a housing 6 shown in FIGS. 2 and 3. Finally,
connections are formed by technical joining between the sheet-metal
foils 4, 5 and the housing 6, for example during a brazing
process.
[0049] FIG. 2 diagrammatically illustrates a longitudinal section
through an exemplary embodiment of the honeycomb structure 1
according to the invention with a housing 6 and a multiplicity of
passages 2 disposed substantially parallel to one another and
formed by the sheet-metal foils 4, 5. A sleeve 10 is disposed
between the sheet-metal foils 4, 5 and the housing 6. The honeycomb
structure 1 has an extent 12. The housing 6 in this case projects
beyond end sides of the sheet-metal foils 4, 5. The connections by
technical joining in this case are formed in such a way that at
least 90% of the ends 8 (shown in FIGS. 1 and 3) of the sheet-metal
foils 4, 5 are connected to a zone 11 of the sleeve 10. The
sheet-metal foils 4, 5 are indirectly connected to a sector 9 of
the housing 6 by this sleeve 10. The formation of connections by
technical joining between the sleeve 10 and the sector 9 of the
housing 6 in this case takes place in a region of the area which is
smaller than the zone 11.
[0050] FIG. 3 shows an end-elevational view of a further exemplary
embodiment of the honeycomb structure 1 according to the invention.
The honeycomb structure 1 has a plurality of layers 3 with smooth
and fully structured sheet-metal foils 4, 5, which form passages 2.
The ends 8 of all of the sheet-metal foils 4, 5 bear against an
inner surface 19 of the housing 6. The layers 3 have been wound
into a honeycomb body 1 in such a way that in a subsection 7 outer
smooth sheet-metal foils 4 are disposed directly adjacent one
another. In particular, an S-shaped profile of the layers 3 has
been formed around two winding points 26. After the layers 3 have
been introduced into the housing 6, connections are formed by
technical joining between the components of the honeycomb structure
1. These connections in this case are made in an end-side, outer
subregion 20.
[0051] FIG. 4 diagrammatically illustrates how known honeycomb
bodies of the prior art were produced. In that case, smooth
sheet-metal foils 4 and structured sheet-metal foils 5 were
alternately combined to form layers 3, each having the same number
of smooth sheet-metal foils 4 and corrugated or structured
sheet-metal foils 5 occurring in each layer 3 (i.e. the ratio of
smooth sheet-metal foils to structured sheet-metal foils was 1:1).
As can be seen from the right-hand illustration, deformation of
these layers 3 led to the formation of contact regions 28 in which
structured sheet-metal foil regions would bear against one another
and/or be disposed directly adjacent one another in honeycomb
bodies 27 formed therefrom. That occurred in particular if an
S-shaped profile 13 was selected and the extent 12 was relatively
small. As can be seen from FIG. 4, that led to a relatively
irregular formation of passages 2, having an adverse effect on the
efficiency of a honeycomb body of that type with regard to its
subsequent intended use. That is avoided by the honeycomb structure
1 according to the invention.
[0052] FIG. 5 diagrammatically depicts examples of some profiles 13
of different honeycomb structures 1 according to the invention. In
alphabetical order, these represent the following profiles 13: an
S-shape in FIG. 5A, a W-shape in FIG. 5B, a helical shape in FIG.
5C, a Z-shape in FIG. 5D, a U-shape in FIG. 5E, and a V-shape in
FIG. 5F.
[0053] The honeycomb structure proposed herein is particularly
simple to produce and has a high, constant efficiency during its
subsequent use in the exhaust system of mobile internal combustion
engines. In particular, the honeycomb structure has a durable
construction and is suitable in particular for extreme ambient
conditions, for example in the immediate vicinity of the internal
combustion engine.
* * * * *