EP0818615B1 - Catalyst housing - Google Patents

Description

The invention relates to a catalyst housing according to the preamble of claim 1.

Catalyst housings, such as are used to connect a catalytic converter in exhaust systems of internal combustion engines, in particular of motor vehicles, are available in various embodiments, with two systems having become established in the market. According to the first system, a monolith coated with a catalytically active material (ceramic or metallic construction) is wrapped with a buffing mat, which has the task of storing the monolith. On this Blähmatte turn a metal jacket is placed, which is wound with a specified force and thereby holds the monolith in position. This tensioned metal jacket is stapled to the front sides, whereby a tight fit of the monolith is guaranteed. On the front side inlet and outlet funnels are attached, which are aligned according to the requirements (connection of the exhaust pipe). The attachment takes place by means of a welded circular seam to the wound converter. After closing the sheet metal jacket by means of a weld, the finished winding converter is obtained. Despite the high functional and process reliability of this wound converter, weak points have been identified in series production. On the one hand, the high weight turns out to be disadvantageous and, on the other hand, there is often a connection of the funnels to the monolith surfaces which is often unfavorable to the current.

Another on-market embodiment of a catalyst housing, the shell converter, overcomes these disadvantages. In contrast to the winding converter, the shell converter consists of the monolith, a soaked inflatable mat and two half-shells (one upper and one lower shell). However, the tray converter has a lack of process safety and also the geometry defined by the shell shape presents difficulties in adapting to the underbody of motor vehicles. With variable Subfloors of motor vehicles is also a difference in the connection pipe converter to compensate for a complicated and therefore costly pipe adaptation.

When assembling the shell-type converter, the Blähmatte is immersed in an organic liquid in order to facilitate their installation. This organic liquid then evaporates, so that the Blähmatte is very porous. In addition, in the thermal load of the converter, the converter shells in contrast to the monolith very different, so that for a reliable operation of the shell converter production with very tight tolerances is necessary. If the tolerances are not adhered to, the monolith, after the motor vehicle has been put into operation, gets freedom of movement, which can lead to failure of the catalytic converter. Such catalyst housing arrangements are known, for example from DE 42 23 648 C . DE 38 21 397 C . DE 38 11 224 C and DE 37 29 994 A ,

Another difficulty in the production of the catalyst housing is the connection of the funnel to the housing body. The funnel, which has the task of compensating the differences in diameter between the inlet and outlet pipe and the catalyst body, should on the one hand ensure a controlled exhaust gas flow and, on the other hand, protect the bubble mat from being washed out by the pulsating exhaust gas flow. For this purpose, usually the hopper collar is employed at a 90 ° angle to the funnel axis, as for example from the DE 34 30 398 A , Figure 5 is known.

Such hoppers are usually made from a sheet metal blank by deep drawing, but with two disadvantages. On the one hand you need sheet metal blanks with a high thickness to get a still small diameter weldable for the connection of the exhaust pipe after deep drawing. The second drawback is the 90 ° funnel setting to the funnel collar, which is welded to the catalyst housing. It may happen that, depending on the location of the monolith diameter in its tolerance field and possible decentralized attachment of the funnel collar to the catalyst housing, an effective monolith area of up to 15% is obscured. An improvement shows the funnel connection according to FIG. 1 of the DE 34 30 398 A in which there is only a slight overlap of the effective monolith face. However, this connection requires a high degree of precision in the manufacture of the housing parts and the funnel, since otherwise no accurate insertion of the funnel into the housing is possible.

This becomes even more problematic in the FIG. 1 present welding of three sheet metal layers at the entrance hopper.

Another funnel connection is from the DE 34 30 399 A in which the large diameter of the funnel is folded over the catalyst housing. However, this is a very expensive process and does not eliminate the disadvantage of eventual overlap of the effective catalyst endface.

From the document US 5,118,476 is a catalyst housing for exhaust systems of internal combustion engines known with a tubular central part and two funnels for connecting the housing. The funnels are connected with their large diameter with the middle part. The middle part picks up a catalyst core. The small diameter of the funnel can be connected to a fluid inlet or outlet part. Furthermore, from the US 5,118,476 a two-part catalyst housing with integrated funnels known in which the catalyst core is fixed in the overlap region of the two parts. Furthermore, from the US 4,087,039 a catalytic converter with a three-part housing and an inlet and an outlet cone and a middle Tubusring known. A housing for a catalytic converter with a tube shell and funnel-like end caps is in the EP 263,893 described.

Object of the present invention is to provide a catalyst housing, which on the one hand has a low weight and on the other hand, a favorable exhaust gas flow.

This object is achieved with the features of the independent claim.

The subclaims show particularly preferred embodiments of the invention. According to the invention, a so-called tube funnel is used as the inlet and / or outlet funnel of the catalyst housing instead of a deep-drawn funnel. That is, the blank geometry of the hopper is a pipe. The tube is expanded in a follower tool to the required large diameter and the required Small diameter retracted. Preferably, the retraction of the tube is done by pressing (pulling) of the tube funnel in a die.

For a simple manufacturing process, the tube funnel is manufactured in two stages, with the expansion of one end to the retraction or vice versa. By this method, it is possible to provide the blank (semifinished product) with the just necessary thickness, which is necessary for the expansion.

According to the invention, the hopper has at its large diameter a material thickness which is at most 90% of the material thickness at its small diameter. In particular, the material thickness at the large diameter is at most 80%. However, the material thickness at the large diameter is advantageously at least 40% and in particular at least 60% of the material thickness at the small diameter, since otherwise the funnel becomes too heavy again and, secondly, the weldability becomes problematical either at the large diameter or at the small diameter. With this thickness distribution on the hopper, it is possible for him to optimize weight and on the other well weldable at both ends, so that on the one hand the separate catalyst jacket can be easily welded to the large diameter of the funnel and the separate exhaust pipe to the small diameter of the funnel ,

In contrast, the prior art hoppers have a reverse weight distribution, i. H. The large diameter has a thicker wall thickness than the small diameter, making these funnels much heavier.

Due to the combined production of the tube funnel by widening of the large diameter and pulling the small diameter is achieved that on the one hand, the funnel material at its large diameter is not too thin and on the other hand, the small diameter of the funnel receives a not excessively high material thickness. In addition, a possible material overstretching on the large diameter is avoided in this manufacturing method. With the manufacturing method of drawing and widening a particularly favorable wall thickness distribution as well as mass distribution is achieved at the two diameters of the funnel.

In order to avoid the disadvantages of the funnel connection to the separate central part of the catalyst housing, the wide end of the funnel is attached with its front side to a connection slope of the central part and connected there in particular by soldering or welding. Likewise, the middle part can also be connected to one of its end faces at a connecting slope of the large diameter of the funnel, although the first embodiment is preferred. The connection slope is preferably directed inward for manufacturing reasons. The connection slope is advantageously produced by rolling.

The length of the connection slope is advantageously kept as short as possible, i. so that a gapless connection of the two parts is possible within the allowable manufacturing tolerances for the middle part and the funnel. Advantageously, the Anbindungsschräge is at an angle of 10 ° to 70 ° and in particular from 20 ° to 50 ° to the longitudinal axis, since under this geometry larger manufacturing tolerances are still possible with short connection slopes.

The connecting bevel cross-part may also be formed with a connection bevel, which is then directed opposite (to the outside). This connection slope advantageously has an angle to the longitudinal axis ≦ the angle of the inwardly directed connection bevel.

The connection bevel advantageously not only compensates for a diameter tolerance on the funnel or the middle part, but also conceals virtually no effective monolith surface at the same time, wherein in addition the funnel geometry (cf. DE 34 30 398 and 34 30 399 ) is simplified.

As catalyst core according to the invention preferably ceramic or metallic monoliths are used, wherein one or more monoliths can be accommodated in the central part of the catalyst housing.

Most preferably, the tubular central part in which the catalyst core is wound, d. H. is - as described above - made of a metal strip, which surrounds the Katalysatorkem (with the catalyst core against the middle part supporting intermediate layer, in particular mat).

According to the invention, the funnel described above is preferably arranged on the inlet and outlet side of the middle part.

The invention will be described in more detail below with reference to an embodiment and drawings.

Figur 1

ein Katalysatorgehäuse gemäß dem Stand der Technik;

Figur 2

ein Katalysatorgehäuse mit Rohrtrichtern; und

Figur 3

einen Schnitt durch den Mittelteil des Katalysatorgehäuses.

Show it

FIG. 1

a catalyst housing according to the prior art;

FIG. 2

a catalyst housing with tube funnels; and

FIG. 3

a section through the central part of the catalyst housing.

In FIG. 1 the usual today winding converter 20 is shown in section, which is composed of a middle part 21 and an inlet funnel 22 and an outlet funnel 23. The metal jacket 21 encloses a catalytically coated monolith 24 with the interposition of a Blähmatte 25th

In the production of the wound converter 20, the catalytically coated monolith 24 is wrapped with the Blähmatte 25, which has the task to store the monolith 24. On the Blähmatte 25 then the metal jacket 21 is placed and wound with a specified force on the Blähmatte (pulled). This will stretch the unit. The tensioned metal jacket 21 is then stapled at its ends, whereby a tight fit of the monolith 24 is ensured. In order to compensate tolerances, the funnels 22, 23 funnel collars 27, 28, which are placed at an angle of approximately 90 ° to the longitudinal axis. The funnel collars arise during deep drawing of the funnels 20 to 23 from the corresponding sheet metal blanks by clamping the edge of the board.

The funnel edge 27 and 28 respectively has the largest material thickness of the funnels 22 and 23, respectively, since there is almost no pulling of the material. This thickness exceeds the thickness of the small diameter 29 or 30, since the output thickness of the sheet metal plate must be selected such that the small diameter after deep drawing have a still weldable thickness for joining and welding with the input and output tube (not shown). From manufacturing side therefore there is the problem that during deep drawing the wall thickness at the large diameter equal to the blank wall thickness (the sheet metal plate). At the small diameter 29 or 30, however, the wall thickness by the deformation is far below the Rohteilwandstärke. However, since you do not have to realize a welded joint at any diameter, a minimum wall thickness is required here. This certain minimum wall thickness can only be affected by changes in the blank dimensions, so that the blank wall thickness and thus the part weight for the production must be increased, although it is not required for the connection to the middle part.

Another disadvantage is the funnel position 27 or 28, through which, depending on the radial position of the monolith 24 in its tolerance field, a masking 31 of up to 15% of the cross-sectional area F of the monolith 24 can come.

These disadvantages are met with the catalyst housing 10 (FIG. FIG. 2 ) avoided. For the inlet funnel 2 as well as the outlet funnel 3, funnel tubes are used whose blank geometry is a tube. This tube is expanded or contracted in two manufacturing operations, whereby large diameter 7 or 8 arise with relatively low wall thicknesses, which, however, are still weldable. Since the low wall thickness lies at the large diameter 7 or 8, the tube funnels 2 and 3 are significantly lighter than the funnels 22 and 23, respectively, in which the low wall thickness lies at the small diameter 29 or 30.

Furthermore, the tube funnel 2 or 3 avoid the connection problems to the metal jacket 1 by a new connection geometry. In this connection, the metal jacket 1 is inclined at its ends 11 and 12 at an angle of about 30 ° to the horizontal (longitudinal axis), so that connecting slopes arise. In this connection bevels 11 and 12 diameter tolerances of the wound sheet metal jacket 1 with respect to the Großdurchmessem 7 and 8 of the tube funnel 2 and 3 compensated. As a result, the large diameter 7 and 8 can be welded parallel to the axis to the connecting bevels 11 and 12 respectively. At the same time cover the Anschrägungsschrägen 11 and 12, the Blähmatte 5, so that they can not be washed out by the pulsating exhaust gas flow. On the other hand, however, there is no overlap of the channels 13 of the catalyst core 4, so that its effective cross-section can be fully utilized.

In FIG. 3 It can be seen that in the embodiments according to FIG. 1 respectively. FIG. 2 There is no difference in cross-section. In both cases, a wound metal jacket 1 or 21 is present, which is welded at 14 overlapping a pipe part. Within the metal jacket 1/21 of the catalyst core (monolith) 4/24 is arranged, which is supported via a mat 5/25 against the metal jacket 1/21. For the entire middle part is preferred only the Difference of the Anbindungsschrägen 11 and 12, if they are formed in the metal jacket 1.

Furthermore, it can be seen from the figures that according to the invention, as well as in the prior art, the funnels 2 and 3 can be performed asymmetrically. For this purpose, the tubular blank is preferably first drawn at one end in a die and then, for the production of the large diameter, expanded asymmetrically to the longitudinal axis of the small diameter.

Claims (13)

1. catalytic converter housing, especially for exhaust systems of internal combustion engines, especially in motor vehicles, which is made up or can be made up of metallic parts, at least one part of which is a separate tubular central part (1), which accommodates a converter core (4), and at least one part is a funnel (2, 3) through which exhaust gas can flow, which is connected or can be connected by its large diameter (7, 8) to the central part (1) and which can be connected or is connected by its small diameter (9, 9') to a part feeding in or leading away a fluid, especially a pipe, characterized in that the large diameter (7, 8) is produced by stretching and the small diameter (9, 9') is produced by drawing in the funnel material and the funnel (2, 3) has at its large diameter (7, 8) a thickness of material which is at most 90% of the thickness of material at its small diameter (9, 9').
2. Catalytic converter housing according to Claim 1, characterized in that the large diameter (7; 8) is connected, especially soldered or welded, by its end directly to a connection bevel (11; 12) of the central part (1) and/or the central part (1) is connected, especially soldered or welded, by one of its ends directly to a connection bevel of the large diameter (7, 8).
3. Catalytic converter housing according to Claim 1 or 2, characterized in that the thickness of the material at the large diameter is at most 80% of the thickness of the material at the small diameter and/or is at least 40% of the thickness of the material at its small diameter (9, 9').
4. Catalytic converter housing according to one of the preceding claims, characterized in that the large diameter is produced by expansion.
5. Catalytic converter housing according to one of the preceding claims, characterized in that the funnel is produced from a piece of tube.
6. Catalytic converter housing according to one of the preceding claims, characterized in that the funnel (2, 3) is formed from a piece of tube by expanding one end and drawing in the other end.
7. Catalytic converter housing according to Claim 6, characterized in that drawing in is performed in a die.
8. Catalytic converter housing according to Claim 6 or 7, characterized in that the funnel (2, 3) is expanded and drawn in, respectively, in two successive production operations.
9. Catalytic converter housing according to one of Claims 2 to 8, characterized in that the connection bevel is at an angle of between 10° and 70°, in particular 20° to 50°, to the longitudinal axis of the converter core and is directed inwards or outwards.
10. Catalytic converter housing according to one of the preceding claims, characterized in that one or more ceramic or metallic converter cores (4) (monoliths) are arranged in the central part (1).
11. Catalytic converter housing according to one of the preceding claims, characterized in that the central part (1) is wound, in particular wound from a sheet-metal strip.
12. Catalytic converter housing according to Claim 10 or 11, characterized in that the central part (1) is wound around the converter cores (4).
13. Catalytic converter housing according to one of the preceding claims, characterized in that funnels (2, 3) are arranged at both ends of the central part (1).

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