EP0151229B1 - Matrix for catalytic reactor - Google Patents

Description

The invention relates to a matrix for a catalytic reactor for exhaust gas purification according to the preamble of claim 1, as they are preferably used for exhaust gas purification in internal combustion engines or power plants.

A matrix of this type is known (DE-C-27 33 640), in which steel strips are either in two layers, namely in the form of a smooth strip and a corrugated strip, or only in one layer in the form of specially designed corrugated strips Matrix are wound up. The sheet steel strips are designed so that each lobe-shaped punched-out portions of one layer press into corresponding openings in the adjacent layer, so that the wound layers of the sheet steel strips are secured in the axial direction. It is also known (DE-A-29 02 779), in order to increase the turbulence of the flow through such a matrix, either to apply strips of corrugated metal sheets to smooth steel sheet strips or to connect individual smooth strips with a corrugated sheet metal.

On the one hand, all known designs have the disadvantage that the production of such a matrix is relatively complex. The main disadvantage, however, is that the known types of matrix can only be used in approximately circular tubular housings due to the winding process, and that the design of the outer shape of such reactors is limited by the structure of the matrix. Another disadvantage is that a radial compensation of the exhaust gases flowing through the matrix and the reactor is not possible or only possible incompletely, even if steel strips of the type mentioned above are provided with openings.

A matrix (GB-A 14 91 206) is also known, which is formed by folding a sheet steel strip onto one another. In the known design, however, this sheet steel strip consists of different sections which follow one another in the longitudinal direction, one of which is designed in wave form and the adjoining section is designed as a smooth strip section. When these different sections are placed one on top of the other, a smooth section lies against a corrugated section. With this type of construction, the starting tape used to fold the matrix must be matched to the desired matrix form from the outset. The production of such an output tape is also complex.

The invention is therefore based on the object of designing a matrix of the type mentioned at the outset in such a way that reactors with largely any desired external shapes can be created without great construction expenditure, which also offer the possibility of better radial compensation of the flow profile of the exhaust gas.

To achieve this object, the invention is based on a matrix of the type mentioned in the characterizing features of claim 1. This configuration allows the individual layers of the steel strip to be joined together in a relatively simple and largely free manner. Regardless of the direction of folding, two corrugated sections can never lie together and slide into one another. It is also advantageous that the folded layers remain open on one side due to the folding process. In contrast to a wound matrix, where gas compensation is only possible in the circumferential direction, there is a largely simpler possibility for the radial passage of the exhaust gas. This leads to a more even flow profile. As a result, the radially outer layers of the catalyst material can also participate in the reaction process. The matrix can be better used.

If the individual layers of the tape are folded onto one another in an unequal length according to the features of claim 2, then oval or round inserts can be realized without requiring a complicated structure consisting of several parts. If layers of the same length are arranged in the direction of folding, rectangular or rhombic reactors can be constructed so that, depending on the space available, for example, in a motor vehicle, the shape of the matrix for the reactor for exhaust gas purification can be adapted to this space.

In order to simplify the manufacturing process, it can be provided that the steel strips used to form the matrix are provided with prefabricated kinks at the folds, for example in the manner of perforations, so that the production of a matrix according to the invention, the individual layers of which, for example, zigzag -folded onto one another, can be achieved in a simple manner in that a single band folds behind a printer, for example in the same way as continuous paper, if it falls vertically into a shaft, is also fed into a shaft, at the folds slightly kinked and thereby folds into the desired matrix shape. The matrix formed in this way can then be inserted, for example, into a two-part housing and pressed together by this and also fastened to one another in the axial direction. But it can also be inserted axially through a funnel into a closed tubular housing.

• Fig. 1 eine Möglichkeit einer erfindungsgemä-Ben Faltung eines für die Herstellung der Matrix verwendeten Stahlblechbandes in Mäanderform,
• Fig. 2 die schematische Darstellung ein in einem zick-zack-förmigen Mäander auf-einandergefalteten Stahlblechbandes zur Bildung eines ovalen Reaktoraußenkörpers,
• Fig. 3 die zick-zack-förmige Aufeinanderfaltung eines Stahlblechbandes zur Bildung eines runden Reaktorkörpers,
• Fig. 4 die zick-zack-förmige Aufeinanderfaltung eines Stahlblechbandes zur Bildung eines rechteckigen Reaktorkörpers,
• Fig. 5 eine perspektivische Skizze eines Reaktors, der durch das Aufeinanderfalten eines aus drei Lagen bestehenden, für die Bildung der Matrix verwendeten Stahlblechbandes hergestellt ist und
• Fig. 6 eine perspektivische Teilansicht des für die Herstellung der Matrix der Fig. 5 verwendeten Stahlblechbandes.

The invention is outlined in the drawing using exemplary embodiments and is explained in the following. Show it :

• 1 shows a possibility of a folding according to the invention of a sheet steel strip used in the production of the matrix in a meandering shape,
• Fig. 2 is a schematic representation of a zigzag-shaped meander folded on one another to form a sheet steel strip oval reactor outer body,
• 3 the zigzag-shaped unfolding of a sheet steel strip to form a round reactor body,
• 4 shows the zigzag-shaped unfolding of a sheet steel strip to form a rectangular reactor body,
• Fig. 5 is a perspective sketch of a reactor which is made by unfolding a three-layer steel sheet band used for forming the matrix and
• FIG. 6 is a partial perspective view of the sheet steel strip used for the production of the matrix of FIG. 5.

1 to 4 show possibilities of how sheet steel strips according to the invention can be folded into a matrix for a catalytic reactor for exhaust gas purification. For example, a strip of the type shown in FIG. 6 can be used as the steel strip, which is composed of two smooth steel strips 1 with openings 2 and an intermediate corrugated strip 3, which are soldered to one another, for example. Such a tape cannot slide into each other when it is folded up.

Tapes of this type can be folded in a meandering manner in the manner shown in FIG. 1 as a single continuous tape 7, so that a matrix according to FIG. 1 with a rectangular outer cross section is created, which can be inserted into a rectangular housing 8. It is simpler to provide a zigzag meander as shown in FIG. 2, 3 or 4 for the folding, whereby in each case prefabricated folding points, for example in the manner of a perforation, can be provided at the folding points 9, which lead to the fact that the continuous Band T, which is folded in a zigzag shape, automatically superimposes on the individual layers 7a, 7b, for example when it is lowered from above into a corresponding shaft and folds up there like a paper strip. It is possible, as indicated in FIGS. 2 and 3, to provide the individual layers 7a, 7b with a different fold length a or b, so that oval outer dimensions for insertion into an oval tubular housing 10 - as in FIG. 2. - or in a round tubular housing 11 - as in Fig. 3 - can be achieved by the folding process. Of course, it is also possible to form the individual layers with the same fold length b as in FIG. 4, so that the matrix formed in this way can be inserted into a rectangular outer housing 12 similar to that in FIG. 1.

In a practical embodiment, this can be done, for example, as indicated with reference to FIG. 5, in that a sheet steel strip of the type as shown in FIG. 6 is folded onto one another in the manner shown in FIG. 2 and then between the upper part 13 and the lower part 14 is jammed and thereby also in the axial direction, d. H. in the direction of the flow, which is indicated by the arrow 15. A matrix formed in this way, in which, of course, the individual sheets 1 and 3 provided for production are coated with catalyst material in a known manner, has the advantage that it is very easy to produce. Due to the arrangement of the openings 2, gas equalization is also possible perpendicular to the boundary surfaces 17 of the individual layers 7A, 7B. The clear overall cross section of all openings 2 can be chosen so that this radial compensation is achieved to form a uniform flow profile. It has been shown that this is generally the case if the total cross section of the openings 2 is more than 5% of the area of the boundary surfaces 17. The openings can be provided in the corrugation direction or transversely thereto (2 '), which is more advantageous since they overlap better when layering.

Claims (4)

1. A matrix for a catalytic reactor for exhaust gas cleaning, preferably in internal combustion engines, which is made from a continuous sheet steel strip which can be coated with catalyst material and which is folded upon itself in a zig-zag configuration and which has regions provided with corrugations forming after the folding operation flow passages through which flows the exhaust gas which is fed to a tubular housing or the like for the matrix, characterised in that the sheet steel strip (7, T) is a sheet steel strip (7, 7') which is the same throughout and which is made up from three layers (1 and 3 respectively) in which the two outer layers comprise smooth strips (1) with or without apertures (2) therethrough and the middle layer (3) is a corrugated strip which is also with or without apertures therethrough or interruptions therein so that the sheet steel strip can be folded as desired in both directions.

2. A matrix according to claim 1 characterised in that the fold layer portions (7a, 7b) are of unequal lengths (a, b) in the folding direction.

3. A matrix according to one of claims 1 and 2 characterised in that the sheet steel strips (7, 7') are provided at the fold locations with pre-fabricated bend locations (9).

4. A matrix according to claim 3 characterised in that the bend locations (9) are in the form of perforations.

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