Abstract:
A method for producing a metallic carrier body includes introducing a sheet into a receptacle. The sheet undergoes at least partial deformation upon introduction into the receptacle. A catalyst carrier body for an exhaust gas system of an internal combustion engine may be produced by the method.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a method for producing a metallic carrier body. The invention also relates to a metallic carrier body, in particular a catalyst carrier body for exhaust gas systems of internal combustion engines. 
     Metallic carrier bodies, which are also referred to as honeycomb bodies, in particular catalyst carrier bodies for exhaust gas systems of internal combustion engines, are known, for example, from International Publication Nos. WO 92/02717 and WO 92/02716. 
     A feature common to all of those bodies is that they are formed of a plurality of individual sheets or layers which are at least partially structured. The sheets delimit flow channels, through which an exhaust gas can flow. The sheets are wound or coiled one around the other in order to form individual gas channels. 
     The activity of a catalyst carrier body, which is disposed within an exhaust gas system of an internal combustion engine, depends, inter alia, on the flow conditions in a metallic carrier body. In order to improve the flow conditions, it is proposed, according to International Publication No. WO 92/02717, that at least part of the sheets have structures running approximately parallel to the direction of flow. In at least part of those structured sheets the structures have structure heights and/or structure widths narrowing continuously or in steps in order to form channels having different cross-sectional areas. Another proposal for improving effectiveness and/or the flow conditions in a metallic carrier body is described in International Publication No. WO 92/02716, mentioned above. According to that publication, it is proposed that, as seen in the direction of flow of the channels, the carrier body be constructed in such a way that the number of channels per cross-sectional area, and consequently the cross-sectional area of individual channels, vary in different portions located one behind the other in the direction of flow. 
     Such carrier bodies have high effectiveness and a favorable flow behavior, which is advantageous particularly in the case of large exhaust gas volumes. 
     Such metallic honeycomb bodies are produced by laminating at least partially structured sheets so as to form at least one stack. The laminated stack or laminated stacks are subsequently coiled at least partially one around the other. The stacks that are coiled one around the other are thereafter introduced into a casing tube. The carrier body which is thus produced subsequently has brazing material applied to it and is subjected to a brazing operation, with the result that the individual sheets are connected to one another. In addition, a connection may be made between the sheets or layers and the casing tube. The outlay for producing such carrier bodies is relatively high. 
     SUMMARY OF THE INVENTION 
     It is accordingly an object of the invention to provide a method for producing a metallic carrier body, and a metallic carrier body for an exhaust gas system of an internal combustion engine, which overcome the hereinafore-mentioned disadvantages of the heretofore-known methods and devices of this general type and in which the method simplifies the production of the carrier body and the carrier body has a simplified structure and high effectiveness. 
     With the foregoing and other objects in view there is provided, in accordance with the invention, a method for producing a metallic carrier body, in particular a catalyst carrier body for an exhaust gas system of an internal combustion engine, which comprises introducing at least one sheet into a receptacle while undergoing at least partial deformation of the at least one sheet. 
     The concept according to the invention of a method for producing a metallic carrier body, in particular a catalyst carrier body for an exhaust gas system of an internal combustion engine, follows an entirely novel route in order to produce metallic carrier bodies. Contrary to the known production method, in which an ordered structure of the carrier body is always formed, it is proposed, in the method according to the invention, to introduce at least one sheet into a receptacle, with that sheet at the same time undergoing at least partial deformation. The structure of the gas passages within the carrier body is produced through the use of the deformed sheet. An essentially completely unordered structure of gas passages, which communicate with one another, arises within the receptacle. This ensures that, when an exhaust gas flows through such a carrier body, it undergoes very good intermixing which leads to high effectiveness of a metallic carrier body used as a catalyst carrier body. 
     The method according to the invention also has the advantage of ensuring that there is no longer any need for lamination or stack formation before the actual production of the metallic carrier body. 
     It is possible to influence the essentially unordered structure of the carrier body by a suitable choice or variation of production parameters. 
     In accordance with another mode of the invention, the at least one sheet is introduced into the receptacle at a substantially constant speed during the production operation. This simplifies the production operation substantially, since there is no need for any complicated devices in order to produce the metallic carrier body. Another advantage of this procedure is that the deformation behavior of the sheet, which is introduced into the receptacle at a substantially constant speed, is always similar. 
     In order to increase the effectiveness of the production method, it is proposed to introduce a plurality of sheets into the receptacle simultaneously. These sheets influence one another in that they are at least partially deformed while they are being introduced into the receptacle. 
     In accordance with a further mode of the invention, when a plurality of sheets are introduced into the receptacle simultaneously, each sheet is introduced into the receptacle at a substantially constant speed. A method in which the speed of each sheet is substantially identical is preferred. It is thereby possible to convey all of the sheets into the receptacle through the use of a single drive. 
     The loading of the carrier body with at least one sheet and therefore also the size of a catalytically active surface also depend on the degree of deformation of the sheet. 
     In accordance with an added mode of the invention, the speed of each sheet is different in order to obtain portions which have different deformations within the carrier body and therefore to produce different portions of catalytically active surface. Preferably, the speed of at least one sheet is varied during the production operation. A method in which each sheet is introduced into the receptacle at varying speed is preferred. Varying the speed of each sheet in this way affords the possibility of producing a metallic carrier body which is adapted to a predetermined use or intended use. 
     In accordance with an additional mode of the invention, each sheet is introduced at substantially identically varying speeds. Alternatively, each sheet may be introduced into the receptacle at differently varying speeds. 
     In accordance with yet another mode of the invention, at least the direction in which at least one sheet is introduced into the receptacle is substantially constant, which also simplifies the production of a metallic carrier body. When a plurality of sheets are introduced into the receptacle, it is preferable that the direction in which each sheet is introduced into the receptacle is substantially constant. 
     In accordance with yet a further mode of the invention, in order to prevent zones in which there are large gas channels from occurring within the receptacle, the direction in which at least one sheet is introduced into the receptacle is varied. This may also take place correspondingly when a plurality of sheets are introduced into the receptacle. In this case, an identical variation in the direction of each sheet takes place. This measure also has the advantage of permitting the production of carrier bodies having a varying cross section. These may, for example, be conically constructed carrier bodies. 
     In accordance with yet an added mode of the invention, at least one substantially elongate sheet is introduced, with a twist about its own longitudinal axis, into the receptacle. This is done in order to improve the deformation of at least one sheet when it is introduced into the receptacle. 
     In accordance with yet an additional mode of the invention, at least one sheet is introduced in the form of a band-like sheet into the receptacle. A method in which each band-like sheet is introduced into the receptacle until a respective predetermined loading density of the latter is achieved is preferred. 
     In accordance with again another mode of the invention, at least one sheet in the form of sheet portions is introduced into the receptacle until a predetermined loading is achieved, in order to achieve a relatively high loading of the receptacle with a sheet. These sheet portions are preferably introduced into the receptacle in succession. A plurality of sheet portions may also be introduced into the receptacle simultaneously from different directions and at different speeds. 
     In accordance with again a further mode of the invention, in order to introduce individual sheet portions into the receptacle, the individual sheet portions are accelerated in an introduction station before being introduced into the receptacle. The individual sheet portions are virtually shot into the receptacle. Since the individual sheet portions bump against a wall surface, preferably a baffle wall surface surface, and/or against sheet portions already located in the receptacle, they are deformed. Simultaneous deformation of the sheet portions already located in the receptacle and of those penetrating into the receptacle therefore takes place. The extent of the deformation of the sheets or sheet portions already located in the receptacle and of those being introduced into the receptacle depends on the momentum occurring between the individual sheet portions or sheets. If the agglomerate of sheets or sheet portions which has already formed in the receptacle may be considered as a relatively hard body, relatively high deformation of the sheet penetrating into the receptacle takes place when it collides with this agglomerate. 
     In accordance with again an added mode of the invention, the speed and/or the direction and/or the twist and/or the form of the sheet and/or the acceleration of the sheet portions are varied in dependence on the loading density of the receptacle. If the carrier body is produced, for example, from a band-like sheet, the latter may also be introduced into the receptacle with different accelerations during the production operation. 
     In accordance with again an additional mode of the invention, at least one sheet is introduced into a receptacle which is delimited at least partially by a casing tube of the carrier body and by a baffle wall surface. The baffle wall surface is disposed in an orifice cross section of the casing tube. When at least one sheet is introduced into the casing tube substantially in the axial direction of the latter, that sheet is deformed when it collides with the baffle wall surface. Further deformations may occur due to the fact that the sheet bumps against the casing tube or against the sheet already located in the casing tube. 
     In accordance with still another mode of the invention, at least one sheet is structured before being introduced into the receptacle, in order to improve the deformability of the sheet. The sheet may be given a corrugated structure, for example. 
     In accordance with still a further mode of the invention, at least part of a surface of at least one sheet is made catalytically active, before the at least one sheet is introduced into the receptacle. 
     With the objects of the invention in view, there is also provided a metallic carrier body, in particular a catalyst carrier body for an exhaust gas system of an internal combustion engine, comprising a casing tube; and at least one sheet disposed in the casing tube and forming gas channels; the at least one sheet being at least partially deformed and the gas channels being at least partially delimited, upon introduction of the at least one sheet into the casing tube. 
     In accordance with another feature of the invention, the sheet has a band-like structure. 
     In accordance with a further feature of the invention, the sheet is in the form of sheet portions. The sheet portions and/or the sheet may have an irregular shape and/or form. 
     In accordance with an added feature of the invention, at least one sheet is structured at least partially before being introduced into the receptacle. 
     In accordance with a concomitant feature of the invention, if the carrier body serves as a catalyst carrier body, at least part of a surface of at least one sheet is catalytically active. 
     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 method for producing a metallic carrier body and a metallic carrier body for an exhaust gas system of an internal combustion engine, 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 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 
     FIG. 1 is a diagrammatic, sectional view of a snapshot of an operation for producing a carrier body with one band-like sheet; 
     FIG. 2 is a sectional view of a snapshot of an operation for producing a carrier body with two band-like sheets; 
     FIG. 3 is a sectional view of a snapshot of an operation for producing a carrier body with sheet portions; 
     FIG. 4 is a sectional view of a snapshot of an operation for producing a carrier body with one band-like sheet and with sheet portions; 
     FIG. 5 is an elevational view of a first exemplary embodiment of an introduction station; and 
     FIG. 6 is an elevational view of a second exemplary embodiment of an introduction station. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the figures of the drawings in detail and first, particularly, to FIG. 1 thereof, there is seen a snapshot of an operation for producing a carrier body  1 . The carrier body  1  includes a casing tube  2  with a deformed sheet  4  disposed in the casing tube. The casing tube  2  has a first orifice  5  and a second orifice  6 . The orifices  5 ,  6  have a cross section which corresponds substantially to an inner cross section of the casing tube  2 . The first orifice  5  is closed through the use of a first baffle body  7 . The second orifice  6  is partially closed through the use of a second baffle body  8 . The casing tube  2 , first baffle body  7  and second baffle body  8  delimit a receptacle  3 . An entry orifice  9  is constructed in the second baffle body  8 . The entry orifice  9  extends through the second baffle body  8  and opens out in the receptacle  3 . 
     The band-like sheet  4  is introduced, preferably at high speed, through the entry orifice  9 . The band-like sheet  4  passes through the entry orifice  9  into the receptacle  3 . In this case, a front region of the band-like sheet  4  bumps against a wall surface  10  constructed on the first baffle body  7 . The band-like sheet  4  is deformed as a result of this collision of the band-like sheet which is introduced continuously into the receptacle  3 . A deformed portion of the band-like sheet  4  is designated by reference numeral  11 . 
     The band-like sheet  4  is introduced into the receptacle  3  until a predetermined loading with the band-like sheet  4  has been achieved in the receptacle  3 . The speed at which the band-like sheet  4  is introduced into the receptacle  3  may be constant during the entire production operation. However, it may also vary. The second baffle body  8  is provided in order to prevent the band-like sheet  4  to be introduced into the receptacle  3  from projecting out of the latter toward the end of the production operation. The second baffle body  8  has a wall surface  12 , the function of which corresponds essentially to the function of the wall surface  10  of the first baffle body  7 . 
     The entry orifice  9  is adapted to the cross section of the band-like sheet  4 . The entry orifice  9  may also have a cross section widening toward the receptacle  3 , thereby making it possible to vary the direction in which the sheet is introduced into the receptacle  3 . Arrows R indicate that, during the introduction operation, the band-like sheet  4  can be deflected out of the position illustrated, thereby changing the direction of introduction of the band-like sheet  4 . The change in the direction of introduction of the band-like sheet  4  may take place at any time during the production operation. It may fluctuate between two maximum deflections. Fluctuation preferably takes place sinusoidally. The amplitude of the deflection in the direction of introduction is preferably adapted to the degree of loading of the receptacle  3 . In the initial stage of the production operation, the amplitude of the deflection in the direction of introduction preferably corresponds to the diameter of the casing tube  2 . 
     The band-like sheet  4  is introduced into the receptacle  3  through the use of an introduction station  13 . The band-like sheet  4  is unwound from a stock roll  14  for this purpose. 
     After the band-like sheet  4  has been introduced into the receptacle  3  in conformity with the desired loading, the band-like sheet  4  is severed. The finished carrier body  1  can be removed. 
     FIG. 2 illustrates a snapshot of an operation for producing a carrier body  21 . The carrier body  21  has a conically constructed casing tube  22 . A first orifice  25  of the casing tube  22  is closed through the use of a first baffle body  27 . A second orifice  26  of the casing tube  22  is partially closed through the use of a second baffle body  28 . The casing tube  22 , the first baffle body  27  and the second baffle body  28  delimit a receptacle  23 . 
     The first baffle body  28  has entry orifices  29   a  and  29   b  constructed at a distance from one another. In the illustrated exemplary embodiment, the second baffle body  28  is disposed in the vicinity of the smaller second orifice  26  of the conically widening casing tube  22 . It may be expedient to place the second baffle body at the orifice  25 . 
     A band-like sheet  24   a  passes through the entry orifice  29   a  into the receptacle  23 . A band-like sheet  24   b  passes through the entry orifice  29   b . The band-like sheets  24   a ,  24   b  pass simultaneously into the receptacle  23 . When the receptacle is still empty, the respective ends of the sheets  24   a ,  24   b  bump against a wall surface  30  of the first baffle body  27 . As a result of the collision of the band-like sheets  24   a ,  24   b  with the wall surface  30 , they are deformed and acquire deformation portions  31  which are illustrated diagrammatically in FIG.  2 . The deformation portions  31  delimit gas passages in the finished carrier body  21 . The band-like sheets  24   a ,  24   b  may have the same shape. The sheets  24   a ,  24   b  are introduced through an introduction station  33  which has a common, non-illustrated drive for introducing the two sheets  24   a ,  24   b . The number of band-like sheets  24   a ,  24   b  may be adapted according to production requirements. 
     Another possibility for producing a carrier body  41  is shown in FIG.  3 . In the illustrated exemplary embodiment, the carrier body  41  has, for example, a conically constructed casing tube  42 . Respective orifices  45  and  46  of the conically constructed casing tube are respectively closed through the use of a first baffle body  47  and a second baffle body  48 . The second baffle body  48  has an entry orifice  49 , through which a sheet can be introduced into a receptacle  43 . The sheet preferably is formed of strip-like sheet portions  44 . The sheet portions  44  are accelerated in an introduction station, in such a way that they pass in free flight through the orifice  49  into the receptacle  43 . In the illustrated exemplary embodiment, an introduction station  53  is shown at a distance from the second baffle body  48 . However, the second baffle body  48  may be an integral part of the introduction station  53 . 
     The receptacle  43  is delimited by the casing tube  42 , the first baffle body  47  and the second baffle body  48 . The sheet portions  44  introduced into the receptacle  43  bump against a wall surface  50  of the first baffle body  47 . Due to the impingement of the individual sheet portions  44  against the wall surface  50 , they are deformed, as indicated in FIG.  3 . If a multiplicity of sheet portions  44  have already been introduced into the receptacle  43 , further sheet portions are deformed by impinging onto the deformed sheet portions  44  that are already present and compression of the deformed sheet portions which are already present in the receptacle  43  takes place simultaneously. A relatively low degree of spacing can be achieved when a carrier body is produced with sheet portions. The degree of spacing refers to the ratio of a space volume to the volume of the receptacle. The space volume is understood as the difference between the volume of the receptacle and the total volume of the sheet portions  44  being introduced. 
     The sheet portions  44  are fed sequentially to the introduction station  53 . Feeding takes place through a feed station  55 . In the feed station  55 , the sheet portions  44  are formed by being cut to length from a sheet band  56  which is unrolled from a stock roll  54 . 
     In the exemplary embodiment illustrated in FIG. 3, the sheet portions  44  are brought into the receptacle  43  through the entry orifice  49 . It may be expedient to introduce sheet portions  44  through a further entry orifice in the second baffle body  48 . During the operation of producing the honeycomb body, the accelerations of the sheet portions  44  may be constant. A variation in the acceleration of the sheet portions  44  is preferred, since a virtually laminated carrier body can be achieved thereby. A different number of gas channels are formed in the individual laminations or layers of the carrier body. In other words, the degree of spacing of the individual laminations is different. 
     FIG. 4 diagrammatically illustrates a snapshot of an operation for producing a metallic carrier body  61 . The metallic carrier body  61  has a casing tube  62 . A first orifice  65  of the casing tube  62  is closed through the use of a first baffle body  67 . A second orifice  66  of the casing tube  62  is partially closed through the use of a second baffle body  68 . The casing tube  62 , the first baffle body  67  and the second baffle body  68  delimit a receptacle  63 . 
     The second baffle body  68  has two entry orifices  69   a  and  69   b  constructed at a distance from one another. In the exemplary embodiment illustrated in FIG. 4, a band-like sheet  64   a  passes through the entry orifice  69   a . Sheet portions  64   b  are introduced through the entry orifice  69   b . The finished carrier body  61  includes the band-like sheet  64   a  and a multiplicity of the sheet portions  64   b . During the operation of introducing the band-like sheet  64   a  and the sheet portions  64   b , they are deformed and they fill the receptacle  63 . When a specific loading of the receptacle  63  is achieved, the production operation is terminated. An introduction station  73   a  is provided for the penetration of the band-like sheet  64   a  which is unwound from a stock roll  64   c . The sheet portions  64   b  are introduced through an introduction station  73   b.    
     A finished carrier body  1 ,  21 ,  41  or  61  has a multiplicity of gas channels  80  which are delimited by a sheet or layers in the form of a band-like sheet  4 ,  24   a ,  24   b ,  64   a  and/or a sheet or layers in the form of sheet portions  44 ,  64   b.    
     An exemplary embodiment of an introduction station  33  is illustrated diagrammatically in FIG.  5 . The introduction station  33  has two essentially cylindrical rollers  81 ,  82 . Respective axes  83 ,  84  of the rollers  81 ,  82  run parallel to one another and lie along a common straight line  85 . A spacing of the axes  83 ,  84  along the straight line  85  is somewhat smaller than a sum of the radii of the rollers  81 ,  82 , with the result that a nip  86  is formed between outer surfaces of the rollers  81 ,  82 . The height of the nip  86  is preferably somewhat smaller than the height of the sheet  4  which is conveyed frictionally between the rollers  81 ,  82 . During conveyance through the rollers  81 ,  82 , the sheet  4  can be given a structure, in particular a corrugated structure. For this purpose, the rollers  81 ,  82  are constructed with teeth which are formed on the outer periphery and which engage in one another during the rolling operation. At least one of the rollers  81 ,  82  can be driven by a motor drive which is not illustrated. The drive can preferably be controlled in such a way that the speed at which the sheet  4  is introduced into a receptacle can be varied. 
     An introduction station  53 , as illustrated in FIG. 6, is preferably used in order to introduce sheet portions  44  or  64   b . The introduction station  53  includes two cylindrical rollers  81 ,  82 . The roller  81  is rotatable about an axis  83  and the roller  82  about an axis  84 . The axes  83 ,  84  extend parallel to one another and they lie along a common straight line  85 . The cylindrical roller  81  is displaceable back and forth along the straight line  85 . The roller  81  is connected to a drive, so that this roller  81  is set in rotation about its axis  83 . Sheet portions  44  are applied sequentially onto the outer surface of the roller  82  by a conveying device  87 . When a sheet portion  44  has reached a predetermined position on the outer surface of the roller  82 , the rotating roller  81  is displaced along the straight line  85  in the direction of the roller  82 , so that the outer surface of the roller  81  comes into contact with the sheet portion  44  and the sheet portion is accelerated by the rotating roller  81 . A stop is preferably provided for the roller  81 , so that the travel of the roller  81  is limited in such a way that the outer surface of the roller  81  does not come to bear on the outer surface of the roller  82 . 
     After a sheet portion  44  has been accelerated by the rotating rollers  81 ,  82  and the sheet portion  44  has left a region of engagement with the outer surface of the rollers  81 ,  82 , the roller  81  is moved back into its original position and a further sheet portion  44  is positioned on the outer surface of the roller  82 . The operation is repeated in the manner described.