EP0789807A1

EP0789807A1 - Catalyst carrier element with internal insulation

Info

Publication number: EP0789807A1
Application number: EP95936484A
Authority: EP
Inventors: Wolfgang Maus; Rolf BRÜCK
Original assignee: Emitec Gesellschaft fuer Emissionstechnologie mbH
Current assignee: Vitesco Technologies Lohmar Verwaltungs GmbH
Priority date: 1994-10-21
Filing date: 1995-10-12
Publication date: 1997-08-20
Anticipated expiration: 2015-10-12
Also published as: DE59502127D1; RU2136910C1; US6274099B1; EP0789807B1; WO1996012876A1; CN1069947C; CN1161727A; DE4437718A1; JP3801633B2; JPH10508529A

Abstract

For the catalytic reaction of exhaust gases in an exhaust system, in particular an exhaust system for use in internal combustion engines, a device is proposed with a catalyst carrier element (1) which is provided with a plurality of channels (2) through which the exhaust gas can flow. The free cross section (4) of flow of the channels (2) is partially closed in the direction of flow of the exhaust gas by plastic deformation of the channel walls (11), specifically, in an outer ring region (3) of the catalyst carrier element (1). The plastic deformation can be carried out using, for example, a tool (17) provided for this purpose with a disc (18) which can rotate about an axis (19). The disc (18) is forced against the catalyst carrier element (1) and the casing (10) to create a plastic deformation of the casing tube (10) and channel walls (11) in the form of a peripheral crimp (20) pointing towards the carrier element (1). Other techniques can be applied to create the plastic deformation. The outer channels thus closed off form a thermal insulation against the casing tube (10) which helps the catalyst carrier element (1) to heat up more rapidly in the cold start phase.

Description

DESCRIPTION

Catalyst carrier body with an inner insulation

The invention relates to a device for the catalytic conversion of exhaust gases in an exhaust gas system, in particular in an exhaust gas system of internal combustion engines, with a catalyst carrier body which has a plurality of channels through which an exhaust gas can flow and to a method for producing it such a device.

In order to achieve the most complete possible conversion of the hydrocarbons contained in a combustion engine and the carbon monoxide, the catalytic converter must have a minimum temperature at which the catalytic conversion of the components of the exhaust gas can take place. In general, one speaks of a so-called light-off temperature. The catalyst is heated by the hot exhaust gas in the cold start phase. It is also known to at least partially heat the catalyst carrier body electrically. So that the emission of pollutants during the cold start phase is as low as possible and for mechanical reasons, it has therefore been proposed to design the catalyst carrier body with an internal insulation in order to reduce the heat loss to the housing and the environment.

From DE 36 02 134 AI an apparatus for the catalytic conversion of exhaust gases in an exhaust system, in particular in an exhaust system of internal combustion engines, is known, the one in has a housing arranged metallic catalyst carrier body. The carrier body has a plurality of channels through which an exhaust gas can flow. According to the proposal of DE 36 02 134 AI, the internal insulation of the catalyst carrier body is to be achieved in that a radially inwardly facing collar is arranged in front of the catalyst carrier body, the collar height of which is 3-15% of the catalyst diameter. is at least 1 mm. This collar creates a swirl zone in the exhaust gas flow, through which direct exposure of an outer annular area to the hot exhaust gas is avoided.

A device for the catalytic conversion of exhaust gases in an exhaust gas system is known from DE G 87 12 267.7 U1. The device comprises a catalyst carrier body which has a multiplicity of flow channels for an exhaust gas and which is inserted in a sleeve-shaped housing. The housing is thermally insulated from the catalyst carrier body. The insulation is achieved in that the catalyst carrier body is arranged between end rings which seal at least the outer layer of the metallic matrix body and thus the outer flow channels in this matrix. This results in a closed, non-exhaust gas-flowed air gap in the outer region of the catalyst carrier body, which serves for thermal insulation.

The present invention is based on the object of further developing the known devices for the catalytic conversion of exhaust gases in such a way that the production of a catalyst carrier body with internal insulation is simplified. Furthermore, a method for producing such a device for the catalytic conversion of exhaust gases is to be provided. This object is achieved by a device with the features of claim 1. Advantageous further developments are the subject of the subclaims.

In contrast to the known devices for the catalytic conversion of exhaust gases, an air gap closed in the outer region of the catalyst carrier body is not brought about by additional rings or the like, but rather by the fact that the free flow cross section of the channels is partially, ie. H. is closed in at least one axial section, in the flow direction of the exhaust gas, by plastic deformation of the channel walls. This simplifies the manufacture of the device, since now no collar or end ring has to be introduced into the housing. If the catalyst carrier body consists of several wound sheet metal layers, the plastic deformation can take place during winding. This simplifies the manufacturing process of wound catalysts, since the winding process and the plastic deformation can take place simultaneously.

The channels in the region of the exhaust gas inlet are preferably closed. The plastic deformation of the channels advantageously takes place before the application of a catalytically active layer to the catalyst carrier body. The coating and (washcoat) is usually applied by means of a suspension flowing through the catalyst carrier body. The catalyst carrier body can be arranged so that the suspension flows into the channels closed on one side. The washcoat then fills the channels. It forms thermal insulation. If the catalyst carrier body is arranged in such a way that the closed channels lie in the entry region of the suspension into the catalyst carrier body, the channels cannot be filled with the suspension. This improves the insulation, since the thermal conductivity of the catalyst carrier layer, which would fill the channel completely is better than that of the atmosphere contained in the channels. The channels in the exhaust gas inlet and exhaust gas outlet area are advantageously closed. If the plastic deformation does not completely close individual channels, this is compensated for by the subsequent coating, which closes the small gaps.

In a device in which the channels in the catalyst carrier body are formed in layers one above the other, it is advantageous to close the channels by plastic deformation in up to five layers, preferably two. This achieves an advantageous compromise between the necessary catalytically active surface and the thermal insulation, without the external dimensions of the catalyst carrier body having to be significantly increased.

A method according to the invention for producing a device for the catalytic conversion of exhaust gases in an exhaust gas system is specified by the features of claim 5. Advantageous developments of the method are the subject of dependent claims 6 to 17.

According to the method, it is proposed to partially close the free flow cross section of the channels in the flow direction of the exhaust gas by plastically deforming the channels in an outer ring in the region of the catalyst carrier body. The plastic deformation can take place in that the catalyst carrier body is pushed into a die. When the catalyst carrier body is pushed in, the outer region of the carrier body is deformed, as a result of which the channels are closed. The insertion die can be provided with a conical or an annular wall. Instead of pushing the catalyst carrier body into a die, the plastic deformation of the channel walls can also take place in that a force is exerted on an outer ring area by means of a stamp, which leads to the plastic deformation of the channel walls. The stamp can be ring-shaped or with a wall that runs obliquely from the inside to the outside. If the stamp is provided with a wall running obliquely from the inside to the outside, the free flow cross sections of the channels are closed by bending the channel walls. In the case of an annular stamp, the channel walls are squeezed.

According to a further advantageous idea, it is proposed to hold the catalyst carrier body at its end opposite to the introduction of force during the plastic deformation. This has the advantage that the individual layers of the catalyst carrier body are not displaced relative to one another.

Catalyst carrier bodies are known which consist of a large number of alternating structured and preferably smooth sheet metal layers. Such metallic catalyst carrier bodies are surrounded by a jacket tube. It is therefore proposed to carry out the plastic deformation of the casing tube and the channels in an outer ring area of the catalyst carrier body, such that the free flow cross section of the channels is partially closed in the flow direction of the exhaust gas. The plastic deformation of the casing tube and the channels can take place in that at least one inwardly directed circumferential bead is formed in the casing tube. The bead can also be used to connect the catalyst carrier body to a housing. The plastic deformation is advantageously carried out by free molding. The plastic deformation is preferably carried out by rolling or kneading.

Further features and advantages of the subject matter of the invention are explained on the basis of exemplary embodiments, without being restricted to these exemplary embodiments. Here shows:

FIG. 1 schematically shows a catalyst carrier body and a matrix,

FIG. 2 shows a second form of a die,

FIG. 3 schematically shows a carrier body which was pushed into a die according to FIG. 2,

Figure 4 shows a catalyst carrier body and a stamp in

Cut,

FIG. 5 shows a second exemplary embodiment of a stamp,

FIG. 6 shows a plastically deformed carrier body, corresponding to FIG. 4,

FIG. 7 shows a plastically deformed carrier body by deformation with a stamp according to FIG. 5 and

Figure 8 shows a Trägerköφer in partial section. The catalyst carrier body 1 has a plurality of channels 2 through which an exhaust gas can flow. The channels 2 are formed by an alternating arrangement of structured sheet metal layers 12 and smooth sheet metal layers 13. Each channel has a free flow cross section 4 which is delimited by the channel walls 11. The channel walls are formed by the sheet metal layers 12, 13. For plastic deformation in an outer annular region 3 of the catalyst carrier body 1, the latter is pushed into a die 7, as can be seen from FIG. For this purpose, the catalyst carrier body 1 z. B. held by means of clamping jaws, not shown, and pushed into the die 7 accordingly. 1, the honeycomb body 1 is pushed into the die by means of a tool 14. An annular wall 8 is formed in the die 7. The width of the ring corresponds to the width of the channels to be closed in the honeycomb body 1. A wall 15 adjoins the wall 8, the inner contour of which corresponds to the outer contour of the catalyst carrier body 1.

FIG. 2 shows a second exemplary embodiment of a die 7. The die 7 has a wall 8 which is conical.

FIG. 3 shows a honeycomb body 1 which has been pushed into a corresponding die 7 according to FIG. 2. The channels 2 are closed in the annular region 3. The edge area of the carrier body 1 is correspondingly slanted.

Instead of pushing the carrier body 1 into the die 7, it is proposed to close the plastic deformation of the channels 2 by means of a stamp 9 or 9 '. The stamp 9 or 9 'can be moved back and forth and has an annular shoulder 16. The stamp 9 'differs from the stamp 9 in that it has a wall 21 which extends obliquely from the inside to the outside.

FIGS. 6 and 7 show carrier bodies 1, a carrier body being shown in section in FIG. 6, in which the channels 2 in the outer ring area have been closed by means of the stamp 9. FIG. 7 shows a carrier body in which a stamp 9 'according to FIG. 5 was used.

The production of the device for the catalytic conversion of exhaust gases in an exhaust system, in particular in an exhaust system for internal combustion engines, with a catalyst carrier body 1 surrounding a jacket tube 10 and having a multiplicity of channels 2 can be produced in that the plastic Deformation of the casing tube 10 and the channels 2 takes place in an outer ring area 3, so that the free flow cross section 4 of the channels 2 is partially closed in the flow direction of the exhaust gas. The plastic deformation can take place by means of a tool 17. The tool 17 has a disk 18 which can be rotated about an axis 19 and which has an essentially triangular cross section at its outer edge region. The disc 18 is pressed with a force against the catalyst carrier body 1 and the jacket 10, so that there is a plastic deformation of the jacket tube 10 and the channel walls. A circumferential bead 20 directed toward the carrier body 1 is produced. The tool 17 can rotate around the catalyst carrier body 1. It is also possible to arrange the tool 17 in a stationary manner and to let the catalyst carrier body 1 rotate about its axis.

The formation of the bead 20 can take place in stages, for which purpose the tool 17 is appropriately fed.

REFERENCE SIGN LIST

1 catalyst carrier body

2 channels

3 ring area

4 flow cross section

5 entry

6 exit

7 die

8 wall

9.9 'stamp

10 jacket tube

11 channel wall

12.13 sheet layer

14 tools

15 coat

16 ring

17 tools

18 disc

19 axis

20 surrounds

21 wall

Claims

PATENT CLAIMS

1. Device for the catalytic conversion of exhaust gases in an exhaust system, in particular in an exhaust system of internal combustion engines, with a catalyst carrier body (1) which has a plurality of channels (2) through which an exhaust gas can flow, characterized in that in the free flow cross section (4) of the channels (2) in an outer annular area (3) of the catalyst carrier body (1) at least in a partial area in

Flow direction of the exhaust gas is closed by plastic deformation of the channel walls (11).

2. Device according to claim 1, characterized in that the channels (2) in the region of the exhaust gas inlet (5) are closed.

3. Apparatus according to claim 2, characterized in that the channels (2) are also in the area of the exhaust gas outlet (6) verschlos¬ sen.

Apparatus according to claim 1, 2 or 3, wherein the channels (2) are formed in layers one above the other, characterized in that the channels (2) are plastically deformed in up to five layers, preferably two layers.

5. Process for producing a catalytic device

Implementation of exhaust gases in an exhaust system, in particular in an exhaust system of internal combustion engines, with one

Catalyst carrier body (1), which has a plurality of channels (2) through which an exhaust gas can flow, characterized by plastic see deformation of the channels (2) in an outer annular region (3) of the catalyst carrier body (1), so that the free flow cross section (4) of the channels (2) is closed at least in a partial region in the flow direction of the exhaust gas.

6. The method according to claim 5, wherein the catalyst carrier body (1) for deforming the channels (2) is pushed into a die (7).

7. The method according to claim 6, characterized in that the catalyst carrier body (1) is pushed into a die (7) with a conical wall (8).

8. The method according to claim 6, characterized in that the catalyst carrier body (1) is pushed into a die (7) with a ring-shaped wall (8).

9. The method according to claim 5, characterized in that the deformation of the channels (2) by a stamp (9,9 ') takes place.

10. The method according to claim 9, characterized in that the deformation is carried out by an annular punch (9).

11. The method according to claim 10, characterized in that the annular stamp (9 ') has an obliquely from the inside outwardly running wall (21).

12. The method according to one or more claims 5 to 11, characterized in that the catalyst support body (1) is held up during the plastic deformation.

13. A method for producing a device for the catalytic conversion of exhaust gases in an exhaust gas system, in particular in an exhaust gas system of internal combustion engines, with a catalyst carrier body (1) surrounded by a jacket tube (10) and having a plurality of channels through which an exhaust gas can flow

(2), characterized by plastic deformation of the casing tube (10) and the channels (2) in an outer annular region (3) of the catalyst carrier body (1), such that the free flow cross-section (4) of the channels (2 ) is closed at least in a partial area in the flow direction of the exhaust gas.

14. The method according to claim 13, characterized in that in the casing tube (10) at least one to the Trägerköφer (1) directed, peripheral bead (20) is formed.

15. The method according to claim 13 or 14, characterized in that the plastic deformation takes place by free molding.

16. The method according to claim 15, characterized in that the plastic deformation takes place by rolling.

17. The method according to claim 15, characterized in that the plastic deformation takes place by kneading.