EP1074703A1 - A method of producing a catalyst, especially prefabricating a catalyst housing or tube of modular construction and prefabricated tube produced thereby - Google Patents

Abstract

To produce a catalyst for a motor exhaust system, especially the center section module, a solid block and a shrouding mantle are fitted into a prepared pipe which matches the shape and dimensions of the block with space for the shrouding mantle, to give a constant gap between it and the block. The pipe (1) has a cross section in the shape of a circle, oval or polygon which is prepared pref. with two identical shaped pipe sections (2,3). They are fitted around the block and, after setting the constant gap, they are welded together along their sides. The gap size is pref. 3.8 mm plus or minus 0.6 mm.

Description

The invention relates to a method for producing a Catalyst, in particular a center piece of a motor vehicle catalytic converter in modular design, by insertion at least one monolith and a surrounding bearing jacket in a manufactured tube, which in cross section essentially has the monolith profile plus allowance for the bearing jacket, an adjustment of the tube housing dimension to one constant bearing gap to the monolith. The invention relates also a pipe manufactured according to this.

It has been shown that embedding highly sensitive Monoliths with surrounding swelling mat in prefabricated tubes problematic for an optimal fit in the operation of a catalytic converter is due to the prefabricated monoliths, which can naturally contain deviations in shape and dimensions. So can be too strict for larger manufacturing tolerances, however also a loose seat of the monolith with swelling mat in the Tube housings arise when operating a catalytic converter. Both is undesirable. Too tight a seat can break the seat highly sensitive monoliths during assembly or when struck on the part (e.g. when touching down on the vehicle) lead, especially if it is a thin wall product Ceramic is. Too loose a seat is synonymous with one poor storage and leads u. a. to move and Smashing the monolith under operating loads (vibrations, Exhaust gas pulsation) in the steel jacket and to an aggressive, structure-borne noise behavior (striking of the loose body of metal).

To counter the aforementioned problem, it is from DE 44 33 974 C1 known in a method mentioned at the outset Adjustment of the tube housing dimension to a constant bearing gap by calibrating or expanding a prefabricated one Make tube, which is in one piece with a smaller Cross section is made.

The aforementioned one-piece tube is preferably in winding technology made with a longitudinal weld. In the prefabricated welded tube is then axially the monolith Swell mat inserted. A bearing gap realized in this way Inclusion of the swelling mat between the monolith and the housing or The jacket or tube has a constant cross section only to a limited extent and only allows bearing gaps of limited accuracy.

The object of the invention is to create an aforementioned Process for the preparation of a catalyst, in particular a pipe center piece of a motor vehicle catalytic converter in modular design, after which a particularly simple structurally simple pipe with narrow bearing gap tolerances is.

The object on which the invention is based is achieved by the means specified in claim 1.

The subject of the invention is advantageously further developed by the features of claims 2 to 6.

The essence of the invention is that the oval in cross section or polygonal tube made from two preferably identical tubular molded parts prefabricated and the pipe fittings after insertion of the monolith together with the bearing jacket to form a closed round oval or polygonal tube assembled and then after Adjustment of the constant bearing gap longitudinally welded on both sides become.

In particular, it is provided that each molded pipe part with a offset longitudinal edge is prefabricated, which is a movable Recording for the not offset longitudinal edge of the other pipe molding.

Each molded pipe part can be manufactured separately using winding technology or be bent.

A motor vehicle catalytic converter manufactured by the method according to the invention in modular design with jacket or tube and on taken monolith together with bearing jacket, in particular Swelling mat, characterized in that the jacket or the tube is round, oval or polygonal in cross-section and consists of two preferably identical pipe fittings are assembled and has two longitudinal edges welded together, each Pipe molding a radially outward longitudinal edge owns that in the assembled state of the two pipe fittings the non-offset longitudinal edge of the other pipe molding overlaps.

The area of overlap of the longitudinal edges is in particular as Fit fit, which before welding the Longitudinal edges is a sliding seat through which the bearing gap between the monolith and the jacket or tube can.

In particular, by the double-sided sliding seat the bearing gap accuracy compared to the known one-seam winding process, at which elastic restoring forces are a hindrance, increase significantly, without loss of production to have to put up with. According to the invention, it becomes twice Sliding seat of both pipe fittings used, d. H. it are the two composite pipe fittings in which the monolith and bearing mat are already in place, finely shifted or fine-tuned before the two welds right and left along the pipe dividing lines. The two assembled pipe fittings have and no significant internal stresses after welding that trigger a restoring force and the bearing gap accuracy could affect.

According to the invention, bearing gaps in the range of Realize 3.8 ± 0.6mm.

Various swelling mat gaps can be created by the invention Adjust very well in the horizontal and vertical directions. The manufacturing costs of the shell parts are low. The The invention is suitable for all preferably axially symmetrical Modular cat bodies, in which a depending on the monolith size adjustable source mat gap is required, however also for non-axisymmetric, preferably in cross section polygonal modular cat body.

Fig. 1

ein vorgefertigtes Rohr mit ovalem Querschnitt, wobei das Rohr aus zwei identischen Rohrformteilen zusammengesetzt ist, und

Fig. 2, 3 und 4

vorgefertigte Rohre in anderer Ausführungsform, wobei das Rohr jeweils aus zwei unterschiedlichen Rohrformteilen zusammengesetzt ist.

The invention is described below using exemplary embodiments with reference to the accompanying drawings; show it

Fig. 1

a prefabricated tube with an oval cross-section, the tube being composed of two identical pipe fittings, and

2, 3 and 4

Prefabricated pipes in another embodiment, the pipe being composed of two different pipe fittings.

In a process for producing a catalyst, in particular a centerpiece of a motor vehicle catalytic converter in modular design, by introducing at least one Monoliths and a surrounding bearing jacket in one Tube, which in cross section essentially the monolith profile plus allowance for the bearing jacket, where an adjustment of the tube housing dimension to a constant Storage gap to the monolith takes place, the adjustment of one Tube 1 with a round, oval or polygonal tube cross section through two pre-made identical or different Pipe fittings 2, 3 causes that with respect to each other have a double sliding seat before welding.

The pipe fittings 2, 3 are after introducing the monolith together with the bearing jacket to form a closed round, oval or polygon tube 1 assembled and then after adjustment of the constant bearing gap, longitudinally welded on both sides.

The double sliding seat is set up in that each Pipe molding 2 or 3 with a stepped longitudinal edge 4 or 5 is prefabricated, which is a movable recording for the non-offset longitudinal edge 6 or 7 of the other Pipe molding forms.

Each pipe fitting 2 or 3 can be wound separately are manufactured or bent.

According to FIG. 1, a (not shown in detail) Motor vehicle catalytic converter in modular design with a jacket or Pipe and absorbed monolith and bearing jacket, in particular Swelling mat, a cross-sectionally oval tube 1, which composed of two identical pipe fittings 2, 3 and has two longitudinal edges welded together, whereby each molded pipe part 2 or 3 a radially outward offset Has longitudinal edge 4 or 5, the composite Condition of the two pipe fittings, the longitudinal edge not offset 6 or 7 of the other pipe molding overlaps.

The area of overlap of the longitudinal edges is a snug fit formed before welding the longitudinal edges together is the above-mentioned sliding seat, through which the bearing gap between the monolith and the jacket or tube 1 can be adjusted so that there is a bearing gap of 3.8 ± 0.6mm results.

The two pipe fittings 2 and 3 of the oval shown Pipe 1 have flat jacket surface sections of different lengths open and form dividing lines in the assembled state at different heights.

Alternatively, the two dividing lines can also be the same Height can be arranged, as is the case for example with a round one pipe according to the invention (not illustrated) likewise with the double sliding seat in the parting plane.

While in the aforementioned embodiment according to Figure 1 Tube 1 includes two identical pipe fittings 2, 3, are the Pipes 1 according to Figures 2, 3 and 4 from different Pipe fittings 2, 3 assembled and otherwise with the same offset longitudinal edges as shown in Figure 1 and longitudinally welded in the same way. Again there are overlap areas set up at the longitudinal edges that before welding are basically sliding seats, even if the longitudinal edges are at least partially slightly curved. Also According to these variants, the source mat column can be horizontal as in a vertical direction with the aforementioned Accuracy can be set.

Figure 2 shows in particular a so-called triangular cat Cross section, Figure 3 shows a catalyst in drop form, and Figure 4 shows a catalyst in potato form.

The invention should not be confused with the so-called Half-shell technology, i.e. Manufacture of a closed pipe from two half-shells with radial longitudinal rims in the parting plane, which may still have been turned over. Such radial longitudinal rims just do not allow that double sliding seat according to the invention before welding. A fine adjustment of the bearing gap takes place at the known half-shell technology does not take place. The scope of the pipe is already defined before welding. A change of the pipe diameter can then at most Calibration are accomplished, one compared to the invention much more complex adjustment process.

Claims (6)

Process for the production of a catalytic converter, in particular a middle section of a motor vehicle catalytic converter in modular design, by introducing at least one monolith and a surrounding bearing jacket into a manufactured pipe, which in cross-section essentially has the monolith profile plus allowance for the bearing jacket, with an adaptation of the pipe housing dimensions there is a constant bearing gap to the monolith,
characterized,
that the cross-sectionally round, oval or polygonal tube (1) is prefabricated from two preferably identical tube shaped parts (2, 3) and the tube shaped parts (2, 3) after inserting the monolith together with the bearing jacket into a closed round, oval or polygonal tube (1) assembled and then longitudinally welded on both sides after setting the constant bearing gap. Method according to claim 1,
characterized,
that each pipe part (2 or 3) is prefabricated with a stepped longitudinal edge (4 or 5) which forms a slidable receptacle for the non-stepped longitudinal edge (6 or 7) of the other pipe part. The method of claim 1 or 2,
characterized,
that each pipe part (2 or 3) is manufactured or bent separately using winding technology. Motor vehicle catalytic converter in modular construction with jacket or tube and monolith taken up together with bearing jacket, in particular swelling mat, manufactured according to one of claims 1 to 3,
characterized,
that the jacket or the tube (1) is round or oval in cross-section and is composed of two identical tubular molded parts (2, 3) and has two longitudinal edges welded together, each tubular molded part (2 or 3) having a longitudinal edge (4 or 5), which overlaps the non-offset longitudinal edge (6 or 7) of the other tubular molded part in the assembled state of the two tubular molded parts. Motor vehicle catalytic converter according to claim 4,
characterized,
that the overlap area of the longitudinal edges is designed as a snug fit, which is a sliding fit before welding the longitudinal edges together, through which the bearing gap between the monolith and the jacket or tube (1) can be finely adjusted. Motor vehicle catalytic converter according to claim 4 or 5,
characterized,
that the adjustable (minimum) bearing gap is in the range of 3.8 ± 0.6mm.

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