Patent Application
20070259198
This is a continuing application, under 35 U.S.C. § 120, of copending International Application No. PCT/EP2005/012631, filed Nov. 25, 2005, which designated the United States; this application also claims the priority, under 35 U.S.C. § 119, of German Patent Application DE 10 2004 058 285.8, filed Dec. 2, 2004; the prior applications are herewith incorporated by reference in their entirety.
The present invention relates to a joining material for positioning brazing material on a metallic surface, a process for producing a honeycomb body using such a joining material, a corresponding honeycomb body and a motor vehicle having a corresponding honeycomb body. Such honeycomb bodies are preferably used in the exhaust system of automobiles, in particular as a catalyst carrier body or a filter body.
Honeycomb bodies are generally formed from ceramic material or as a metallic honeycomb structure. A distinction is drawn in particular between two typical forms of metallic honeycomb bodies. An early form, 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 form, in which substantially one smooth sheet-metal layer and one corrugated sheet-metal layer are placed on top of one another and wound helically. In a different form, the honeycomb body is built up from a multiplicity of alternately disposed smooth and corrugated or differently corrugated sheet-metal layers, with the sheet-metal layers initially forming one or more stacks, which are then intertwined with one another. In the process, the ends of all of the sheet-metal layers come to lie on the outer side and can be joined to a housing or tubular casing, resulting in the formation of numerous joints, which increase the durability of the honeycomb body. Typical examples of those forms are described in European Patent EP 0 245 737 B1, corresponding to U.S. Pat. Nos. 4,832,998, 4,803,189, 4,946,822 and 4,923,109 or International Application WO 90/03220, corresponding to U.S. Pat. Nos. 5,105,539 and 5,139,844.
If the honeycomb body is built up from metallic or at least partially metallic layers, technical joining has to be used to connect the layers to one another so as to obtain a durable honeycomb body. The preferred manner of producing the technical joining connection is by brazing. However, a sintering process or even welding may be used as well. Since high temperatures regularly occur in the exhaust system of a motor vehicle, honeycomb bodies are generally brazed at high temperatures, i.e. are subjected to what is known as a brazing or hard-soldering process. In the exhaust system, honeycomb bodies are exposed to high mechanical loads, which are caused on one hand by shocks in the automobile which are also transmitted to the honeycomb body, and on the other hand are thermally induced. The high temperatures of the exhaust-gas stream and the pulsating nature of the exhaust gas cause high mechanical stresses in the honeycomb body. In particular, in the case of honeycomb bodies which are used as a catalyst carrier body, those stresses are amplified even further by the fact that the reaction catalyzed by the catalyst applied to the catalyst carrier body is generally exothermic. Overall, a honeycomb body in the exhaust system is exposed to high thermal gradients and transients. That exposes the honeycomb body to high thermal deformation. If the honeycomb body is rigid, i.e. the layers are joined to adjacent layers in joining regions over the entire cross section and length of the honeycomb body, thermal fractures can easily occur, and for that reason a honeycomb body which is as flexible as possible, and therefore has the minimum possible number of joining locations between the layers, is desirable. On the other hand, an insufficient number of joining locations leads to the occurrence of fatigue fractures at a relatively early time.
Therefore, the aim is for the layers of honeycomb bodies to be joined to one another only at defined, discrete joining regions. For example, German Published, Non-Prosecuted Patent Application DE 103 38 360, corresponding to U.S. Patent Application Publication No. U.S. 2006/0162854, has disclosed a process in which a binder in droplet form is applied only to those locations of the layers which are subsequently to be joined to one another. After the layers have been wound or stacked and intertwined, brazing material in powder form is applied. A similar process is known from European Patent EP 0 422 000, corresponding to U.S. Patent Application Publication Nos. U.S. 2002/0129890 and U.S. 2001/0013390, in which the binder is applied by using a sponge and then pulverulent brazing material is introduced. It is also known from German Published, Non-Prosecuted Patent Application DE 37 11 626, corresponding to Japanese Patent Publication No. JP 63264149, to apply the brazing material by thermal spraying. In that case, discrete joining locations are achieved by the thermal spraying taking place through a corresponding mask. Furthermore, German Published, Non-Prosecuted Patent Application DE 33 12 944 A1 discloses that the offset application of brazing material to layers of a honeycomb body is advantageous for the thermal expansion properties.
All of the processes disclosed herein for the application of brazing material only in discrete joining regions are relatively complex, since suitable measures have to be implemented to ensure either that binder is applied only in certain regions of the layers or that a mask is correspondingly accurately positioned. It is also known to use brazing foil or brazing wire to form the brazed joints. Those in each case form continuous brazing materials which do not allow the formation of discrete joining regions.
is accordingly an object of the invention to provide a joining material for positioning brazing material, a process for producing a honeycomb body, a corresponding honeycomb body and a motor vehicle having a honeycomb body, which overcome the hereinafore-mentioned disadvantages of the heretofore-known products, processes and devices of this general type and in which the joining material allows discrete brazed joints to be formed between two metallic structures.
With the foregoing and other objects in view there is provided, in accordance with the invention, a joining material. The joining material comprises a continuous carrier material, and brazing material formed discontinuously on the continuous carrier material, for positioning the brazing material on at least one discrete joining region of an at least partially metallic surface.
A joining material of this type advantageously allows discrete regions of brazing material to be positioned on joining regions of metallic surfaces without, for example, a binder having to be applied prior to the application of a brazing material. In particular, a joining material of this type can be wound or shaped together with the metallic surfaces which are to be joined. For this purpose, it may be advantageous for the carrier material and/or the brazing material to be provided with binder which fixes the joining material to the surfaces to be joined and thus ensures that accurately defined joining regions of the metallic surfaces can be provided with brazing material and subsequently joined. The carrier material and/or the brazing material may have markings which facilitate positioning of the joining material.
The present invention for the first time proposes a continuous material which can be used to position brazing material in discontinuous regions. Continuous brazing materials, such as for example continuous brazing foil, do not allow targeted application of brazing material and therefore joining of discrete regions of the at least partially metallic surface that is to be brazed, whereas targeted application of brazing material to discrete regions by application of a binder followed by application of brazing material, is complex and requires a high degree of accuracy, in particular when producing honeycomb bodies. The joining material according to the invention advantageously facilitates the handling of the brazing material and simplifies the production of discrete joints between at least partially metallic surfaces. In the present context, an at least partially metallic surface is to be understood as meaning a surface which in particular has a metallic or partially metallic surface. A surface of this type may be formed by a sheet-metal layer, but also by a fibrous layer which may also include ceramic fibers. By way of example, an at least partially metallic surface can also be formed by a mat which has been woven from metal and ceramic fibers and can be used as a filter mat, for example in diesel particulate filters.
In accordance with another feature of the invention, the brazing material is at least partially in the form of a brazing foil.
In accordance with a further feature of the invention, the brazing material is at least partially in the form of brazing material grains.
It is particularly advantageous for the brazing material to be formed as a brazing foil if planar surfaces are to be joined to one another. Brazing foil also offers the advantage that in the event of deformation of the surfaces to be brazed, during which, for example, one surface slides along the other surface, the joining regions formed from brazing foil remain substantially undeformed or unmoved. Forming the brazing material from brazing material grains may be advantageous in particular if it is necessary to bend the joining material, for example through contact with a curved metallic surface. Moreover, forming the brazing material from brazing material grains allows it to be matched in particular, for example, to the thickness and shape of the surfaces to be brazed, since a different brazing material grain fraction is advantageous depending on the thickness and shape of the surfaces in order to ensure optimum attachment of the metallic surfaces.
In accordance with an added feature of the invention, the brazing material is fixed on the carrier material by using a first adhesive.
The first adhesive being used may, for example, be known organic adhesives or water-based adhesives. This first adhesive advantageously imparts good bonding between carrier material and brazing material, so that reliable and accurate positioning of the brazing material can be achieved by positioning the carrier material relative to the at least partially metallic surfaces that are to be brazed.
In accordance with an additional feature of the invention, the brazing material has a second adhesive on a side facing away from the carrier material.
This may be advantageous, in particular, if the brazing material is to be transferred to the metallic surface that is to be provided with brazing material by a rolling movement on the part of the joining material. For this purpose, the joining material is rolled longitudinally onto the at least partially metallic surface, so that the brazing material remains stuck to the surface by the second adhesive. The carrier material can then be easily pulled off the brazing material. The brazing material is therefore stuck to the at least partially metallic surface in a similar way to a label. In this context, it is particularly advantageous for a first adhesive force produced by the first adhesive to be greater than a second adhesive force produced by the second adhesive. It is also advantageous in this context for the brazing material to be in the form of a brazing foil, since in this case it is easy to apply the second adhesive.
In accordance with yet another feature of the invention, a third adhesive is formed on a side of the carrier material which faces away from the brazing material.
This third adhesive makes it easy to fix the joining material. In particular, in this way it is also possible to pre-fix the product that is to be brazed. Furthermore, providing the third adhesive advantageously increases the accuracy of positioning of the brazing material relative to the at least partially metallic surface that is to be brazed, since subsequent movement of the joining material relative to the surface is prevented.
In accordance with yet a further feature of the invention, the carrier material is formed from a metal, a plastic and/or paper, preferably a plastic and/or paper.
Metals and paper as well as plastics make it easy to produce and handle the joining material. Carrier materials which are known from the production of adhesive labels can advantageously be used. A plastic-coated paper can also be used as the carrier material according to the invention.
In accordance with yet an added feature of the invention, the carrier material has a critical temperature above which the support material is destroyed and which is less than or equal to the melting point of the brazing material. In this context, it is particularly preferable for the carrier material, when at least the critical temperature is reached, to be at least partially evaporated and/or at least partially decomposed, preferably to be evaporated substantially without leaving any residues and/or to be decomposed substantially without leaving any residues.
This advantageously ensures that the brazed end product preferably does not have any residues of the carrier material. Evaporation may occur, in particular, when the carrier material is at least partially formed from plastic. Combustion of the carrier material leaving virtually no residues is also possible in accordance with the invention.
With the objects of the invention in view, there is also provided a process for producing a honeycomb body having a honeycomb structure with cavities through which a fluid can at least partially flow. The process comprises at least the following steps:
In step B) and/or step E), the brazing material is at least partially positioned in the form of a joining material according to the invention, and/or in step B) and/or step E), brazing material at least partially in the form of brazing foil is adhesively bonded to at least one joining region and/or at least one attachment region.
Therefore, the process according to the invention allows the production of a honeycomb body having at least partially metallic layers and only one honeycomb structure, as well as a honeycomb body having a honeycomb structure in a tubular casing, preferably a metallic tubular casing. In this case, the joining material according to the invention and/or the stuck-on brazing foil can be used both to form the joints in the honeycomb structure and to join the honeycomb structure to the tubular casing. A combination of any other desired brazing-application processes is possible in accordance with the invention. The brazing foil can be stuck on using known adhesives, for example water-based or organic-based adhesives. The process according to the invention for producing a honeycomb body for the first time allows the economically viable production of honeycomb bodies with offset brazed joints, as is described in German Published, Non-Prosecuted Patent Application DE 33 12 944 A1.
The honeycomb bodies produced in this way are particularly suitable for use in automotive engineering, in particular in the exhaust system of a motor vehicle, where a honeycomb body produced in accordance with the invention can be used, for example, as a catalyst carrier body, a filter body, an adsorber body and/or a muffler. Accordingly, the at least partially metallic layers can at least in part be formed as sheet-metal layers, fibrous layers, filter layers and/or composite layers. A composite layer is to be understood, for example, as a layer which includes both metallic and non-metallic fractions, for example a ceramic fiber layer which is held within a porous metal covering layer. Furthermore, in the context of the present invention, a layer may also include any desired combination of sublayers, for example a fiber layer reinforced with sheet-metal layer sections or the like. In particular, it is also possible to produce honeycomb bodies with large diameters, preferably of more than 150 mm (millimeters) by using the processes according to the invention. In the case of a honeycomb body which is not circular in cross section, the term diameter is to be understood as meaning a characteristic dimension of this cross section, for example a maximum, minimum or mean diameter.
The process according to the invention for producing a honeycomb body makes it possible, with simple and inexpensive positioning of the brazing material, for only defined, discrete joining regions of the layers to be joined to one another and/or defined, discrete joining regions between the honeycomb structure and tubular casing to be joined. In this way, it is possible to produce honeycomb bodies which are flexible. The flexibility may also, for example, be matched to the subsequent use, i.e. in particular to the expected exhaust-gas volumetric flows, the frequency of pulsation of these flows and the momenta of these flows. For example, it is advantageously possible to produce honeycomb bodies with increased durability. These honeycomb bodies can be produced in a simple and inexpensive way using the joining material according to the invention or by sticking on brazing foil. It is preferably possible for a plurality of joining regions to be formed on one layer, in particular also on both longitudinal sides of a layer.
In accordance with another mode of the invention, the brazing foil is cut to the dimensions of the joining region prior to or during process step B).
Therefore, the dimensions of the brazing foil after it has been cut correspond to the desired dimensions of the joining region.
In accordance with a further mode of the invention, the brazing foil is joined to a carrier material.
A brazing foil on a carrier material of this type can form a joining material as described above. However, in this case it is also possible for there to be a continuous brazing foil on carrier material, which is in each case cut according to the required dimensions of the joining regions. The continuous brazing foil may have desired breaking locations, which lead to it being cut to the desired dimensions.
In accordance with an added mode of the invention, at least one at least partially structured layer is provided in process step A).
In accordance with an additional mode of the invention, at least one substantially smooth layer is provided in process step A).
By way of example, it is possible to produce a honeycomb structure in which in process step C) at least one at least partially structured layer and if appropriate at least one substantially smooth layer are wound helically. The term substantially smooth layer is to be understood as meaning a layer which may be smooth but may also have micro-structuring, the structure amplitude of which is significantly smaller than that of the at least partially structured layer. Structuring is to be understood as encompassing in particular a corrugation, for example a sinusoidal, sawtooth and/or triangular corrugation. A structuring is preferably periodic, i.e. has a characteristic repetition length, such as for example a wavelength.
In process step C), a honeycomb structure can, for example, also be formed by at least one at least partially structured layer and if appropriate at least one substantially smooth layer being stacked to form at least one stack, and at least one stack being intertwined in the same direction or opposite directions.
Depending on the detailed construction of the layers, in this way it is possible to form honeycomb bodies which have a honeycomb structure with passages passing through the honeycomb structure in a longitudinal direction. It is also possible and in accordance with the invention to form a honeycomb structure with partially closed passages, with guide structures in the passage wall, with perforations, turbulence-inducing structures, etc.
In accordance with yet another mode of the invention, a structuring of the at least partially structured layer has a characteristic distance between two adjacent structure extremes, in particular a wavelength, in the transverse direction of the structuring, wherein at least some of the joining regions, in the transverse direction of the structuring, have an extent which is greater than the characteristic distance.
If the joining material or the brazing foil is applied to a smooth layer, i.e. the brazing material in process step B) or E) has been positioned on a substantially smooth layer, the preferred extent of the joining regions ensures that at least one structure extreme of the at least partially structured layer comes to bear against the joining region, where it is joined to the substantially smooth layer. In this context, it is particularly preferable for the quotient of the characteristic distance and the extent to be between substantially 1.2 and substantially 5, preferably between substantially 1.5 and substantially 3, and particularly preferably between substantially 1.8 and substantially 2.5.
In addition to the joining material being applied to a substantially smooth layer, it is also possible and in accordance with the invention for the joining material to be applied to an at least partially structured layer. A combination of these two forms of application in one honeycomb body is also possible and in accordance with the invention.
In accordance with yet a further mode of the invention, the dimensions of the carrier material of the joining material substantially at least partially correspond to the dimensions of at least one of the layers.
In the present context, the term at least partially correspond means that a dimension of the joining material substantially corresponds to a corresponding dimension of one of the layers, i.e. by way of example the joining material and a layer have the same length and/or width. This allows the positioning of the joining material and layer to be correspondingly oriented with respect to one another in a particularly simple way.
In accordance with yet an added mode of the invention, the joining material and/or the brazing material is fixed to the layer in process step B) or is fixed to the outer surface of the honeycomb structure and/or the inner surface of the tubular casing in process step E).
This fixing can be achieved through the use of corresponding adhesives on the carrier material and/or the brazing material. If the brazing material is fixed to the layer or the outer surface of the honeycomb structure and/or the inner surface of the tubular casing, the carrier material can be pulled off, so that it is no longer wound into the honeycomb body.
In accordance with yet an additional mode of the invention, before or during process step B) or E) an adhesive is applied to the brazing material and/or to the carrier material.
The application of adhesive to the brazing material and/or the carrier material allows the joining material, the brazing material and/or the brazing foil to be correspondingly fixed to the joining regions of the layers which are to be joined.
In accordance with still another mode of the invention, joining regions are formed on both longitudinal sides of a layer, and the layer in each case has a joining region on only one longitudinal side at a given coordinate.
The layer therefore does not have any point which has joining regions on both longitudinal sides. This makes it possible to construct honeycomb bodies with very good thermal expansion properties, since a honeycomb body composed of corresponding layers permits relative movements of the layers perpendicular to the longitudinal direction of the honeycomb body to a certain extent, without a brazed joint breaking.
In accordance with still a further mode of the invention, the joining regions are formed in such a way that at least two subregions, in which joining regions are produced, are formed in a longitudinal direction of the honeycomb body, and a layer on a longitudinal side only has joining regions in one subregion.
A honeycomb body produced in this way has good thermal expansion properties combined, at the same time, with a good durability. In particular, the offset joining regions also permit a relative movement of the individual layers in the longitudinal direction of the honeycomb body. The subregions are preferably formed on or adjacent end sides of the honeycomb body. As an alternative or in addition, it is possible and in accordance with the invention for a further, third subregion to be formed substantially in the longitudinal direction centrally within the honeycomb body. In this context, it is particularly advantageous if, in the first and second subregions, the joining regions are formed on a first longitudinal side of the layers, while in the third subregion the joining regions are formed on a second longitudinal side, which is the opposite side from the first longitudinal side. A concertina or accordion-like brazed configuration of this nature has proven particularly advantageous with regard to thermal expansion properties and durability.
With the objects of the invention in view, there is additionally provided a honeycomb body. The honeycomb body comprises a honeycomb structure having at least one at least partially metallic layer defining cavities through which a fluid can at least partially flow. Optionally, a tubular casing surrounds the honeycomb structure. Brazing material is positioned or adhesively bonded as a brazing foil in at least some of the joining regions by the joining material according to the invention. The at least one layer is brazed to at least one of itself or an adjacent layer only in joining regions and/or the at least one layer is brazed to the tubular casing only in attachment regions. The brazing material is positioned or adhesively bonded as the brazing foil in at least some of the attachment regions by the joining material.
In particular, the honeycomb body according to the invention may have been produced by the process according to the invention for producing a honeycomb body.
In accordance with another feature of the invention, the honeycomb body has a diameter of substantially greater than or equal to 150 mm (millimeters).
In accordance with a further feature of the invention, the honeycomb body includes at least one layer which has joining regions on both longitudinal sides, and the layer in each case has a joining region on only one longitudinal side at a given coordinate.
In accordance with an added feature of the invention, the joining regions are constructed in such a way that at least two subregions, in which joining regions are produced, are formed in a longitudinal direction of the honeycomb body, and a layer on a longitudinal side has joining regions only in one subregion.
In accordance with an additional feature of the invention, in each case a subregion is formed in the region of or adjacent an end side of the honeycomb body.
In accordance with yet another feature of the invention, a third subregion is formed substantially in the longitudinal direction centrally within the honeycomb body.
With the objects of the invention in view, there is concomitantly provided a motor vehicle, comprising at least one honeycomb body according to the invention or at least one honeycomb body produced by the process according to the invention.
In the present context, a motor vehicle is to be understood in particular as meaning a passenger automobile, a truck, a motorized two-wheeler, a quad bike, a boat or an aircraft.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a joining material for positioning brazing material, a process for producing a honeycomb body, a corresponding honeycomb body and a motor vehicle having a honeycomb body, 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 details and advantages which have been disclosed in connection with the joining material according to the invention, the processes according to the invention, the honeycomb body according to the invention and the motor vehicle according to the invention, can in each case alternatively also be applied and transferred to the others.
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.
Referring now to the figures of the drawings in detail and first, particularly, to
The adhesives 4, 5, 6 are selected in such a way that the adhesive forces allow accurate positioning of the brazing material 3 on the corresponding surfaces. In particular, the first adhesive 4 produces a first adhesive force between the carrier material 2, the first adhesive 4 and the brazing material 3. The second adhesive 5 produces a second adhesive force between the brazing material 3, the second adhesive 5 and the surface to which brazing material is to be applied.
The forces are matched to one another in such a way that the brazing material 3 is stuck onto the corresponding surface that is to be provided with brazing material while at the same time the brazing material 3 is detached from the carrier material 2.
The carrier material 2 is preferably formed of plastic and/or paper. In particular, it is preferable for the carrier material 2 to be formed of a substance which, at a crystal temperature that is lower than the brazing temperature of the brazing material 3, evaporates as far as possible without leaving any residues or decomposes as far as possible without leaving any residues.
The applicators 11 press the individual regions of brazing material 3, which have been provided with a second non-illustrated adhesive 5, onto the substantially smooth layer 7 at predeterminable positions, through movement in an application direction 13, so that corresponding joining regions of the substantially smooth layer 7 are provided with the brazing material 3. If appropriate, it is possible to provide a pressure-exerting roll 12, by which the brazing material 3 is subsequently fixed by applying pressure in a pressing direction 14. The removal of the used carrier material 2 is not illustrated, for the sake of clarity. The substantially smooth layer 7 is moved in a direction of movement 15.
The intertwining operation produces the illustrated pattern of joining regions 18, which are illustrated as small circles. This type of configuration of the joining regions advantageously leads to an elastic, durable honeycomb body 19, which can be used in particular as a catalyst carrier body or filter body in the exhaust system of a motor vehicle. The honeycomb structure 20 is fixed to the tubular casing 21 by way of attachment regions 23 which have been positioned by using a joining material 1 according to the invention.
A first subregion 33, a second subregion 34 and a third subregion 35 are formed in a longitudinal direction 32 of the honeycomb body 19, through which a medium can at least partially flow in the non-illustrated passages 22. The first joining regions 29 are in each case constructed in such a way that the first longitudinal side 28 of an individual layer 7 only has first joining regions 29 on the first longitudinal side 28 of the substantially smooth layer 7. The first joining regions 29 of a layer 7 therefore belong either to the first subregion 33 or to the second subregion 34.
Consequently, there is preferably no layer 7 which has first joining regions 29 in the first subregion 33 and in the second subregion 34.
The first subregion 33 and the second subregion 34 are preferably in the vicinity of or adjacent an end side of the honeycomb body 19. The third subregion 35 lies substantially centrally with respect to the extent of the honeycomb body 19 and/or the layers 7.
A honeycomb body 19 constructed as shown in
The joining material 1 according to the invention can particularly advantageously be used for the production of honeycomb bodies 19, since adjacent layers 7, 17 of the honeycomb body 19 can be joined only in discrete joining regions 18 through the use of the joining material 1, in a simple way. In this way it is possible to produce honeycomb bodies 19 which are elastic and yet durable.
| Number | Date | Country | Kind |
|---|---|---|---|
| DE 102004058285.8 | Dec 2004 | DE | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2005/012631 | Nov 2005 | US |
| Child | 11810079 | Jun 2007 | US |
