EP1272745B1 - Housing with a passivation layer and method for producing a catalyst support body with a housing of this type - Google Patents

Abstract

The invention relates to a housing for a honeycomb body (4), comprising a tubular jacket (1) with an inner wall (2), said tubular jacket (1) having a passivation layer (3) in at least one section of the inner wall (2) for the purpose of specifically modifying a connection to the honeycomb body (4) produced using a joining technique. The invention also relates to a method for producing a catalyst support body with a honeycomb body (4) and an inventive housing. A catalyst support body produced according to this method reduces thermal stresses between the honeycomb body (4) and the tubular jacket (1) and ensures a particularly reliable soldering process during production, even in a vacuum.

Description

The present invention relates to a housing, in particular a jacket tube, for a honeycomb body and on the production of a honeycomb body with such a housing. Such honeycomb bodies are used as catalyst carrier body preferably in exhaust systems of internal combustion engines, in particular of motor vehicles.

In WO 99/37896 a method for producing a honeycomb body is described, which is surrounded by a jacket tube. The honeycomb body and the Jacket tube have due to their different material properties and due to different temperatures during operation a differing thermal Stretching behavior on. It is therefore desirable to have a rigid connection between the honeycomb body and the jacket tube at at least one end region the honeycomb body or at least in certain sub-areas to avoid. For this reason, the sheathed material described in WO 99/37896 Honeycomb body executed with a cuff, which despite production engineering Tolerances of the jacket tube and the honeycomb body to ensure that direct Solder joints between honeycomb body and casing pipe in the at least an end portion of the honeycomb body can be avoided. The use of a Cuff leads to the significant reduction of thermal stresses between Casing and honeycomb body, however, causes a higher production cost.

Furthermore, agents are known which provide a compound of metal surfaces during a high-temperature processing (such as sintering or Soldering) prevent. These usually contain fine ceramic particles, one Binder, as well as a share of diluents and solvents. The binder as well the diluent and the solvent are already at relatively low levels Temperatures are volatile. In the preparation of catalyst support bodies takes place the formation of the connection between the jacket tube and housing preferably in Vacuum, the tendency of these volatilization means to maintain the vacuum significantly and the system by volatile components can be contaminated.

On this basis, the present invention is based on the tasks to provide a housing for a honeycomb body, which selectively joining technical Compounds to compensate for the different expansion behavior of Honeycomb body and jacket tube allows and permanent fixation of the honeycomb body guaranteed for example in an exhaust system and the indication a method for producing a catalyst carrier body with such a Casing.

These objects are achieved by a housing with the features of claim 1 and a method for producing a catalyst carrier body solved with the features of claim 16. Advantageous developments and embodiments of the method are the subject of each dependent Claims.

The housing according to the invention for a honeycomb body comprises a jacket tube with an inner wall, wherein the jacket tube for targeted prevention of technical joining with the honeycomb body in at least one section the inner wall has a passivation layer.

The passivation layer is thermally very stable and prevents any technical joining Connection of the metal surfaces in contact with each other. The section where the passivation layer is located is located at the location of the jacket tube, at the later operation of the catalyst carrier body a relative movement between the honeycomb body and casing pipe is desired to prevent thermal stresses. This is preferably the frontal region in which the hot exhaust gas on the catalyst carrier body meets. Even areas further inward can be so from technical joining be kept free.

Furthermore, the passivation layer prevents due to their insulating property a heat conduction from the honeycomb body to the jacket tube. This is for example especially important if after the shortest possible time after At the start of an automobile, the light-off temperature of a catalytic converter is to be achieved, in which an effective cleaning of the exhaust gas takes place.

According to one embodiment of the housing, the passivation layer is a surface oxide layer educated. The oxides, in particular the metal oxides, have a high thermal stability, which makes a connection more touching Metal surfaces prevented. It is also particularly advantageous that the oxides in be easily generated with components of the material of the jacket tube and an additional material for making the passivation layer is not needed. Such a metal oxide layer may, for example, also by simply roughening the inner wall of the jacket tube in the section getting produced.

According to a further embodiment of the housing is the passivation layer as a ceramic coating layer, in particular with aluminum oxide, executed. The ceramic particles are characterized by particularly high Attractiveness to each other and a very good thermodynamic stability. A ceramic layer of titanium oxide or magnesium oxide is also possible.

According to a further embodiment, the passivation layer is more circumferential Strip formed. This ensures that in this section the entire circumference of the jacket tube solder joints between jacket pipe and honeycomb body avoided and a balance of different strain behavior be allowed.

If the case has an oval or elliptical shape, then it is according to another Embodiment advantageous, the passivation layer in a jacket pipe section to arrange with strong curvature. An oval shape of the housing is for example required if the installation of a catalyst carrier body with the housing bound to certain spatial conditions of an exhaust system is. Experience has shown that it is advantageous to use the technical joining connections to make the flat sides of such a body and therefore to the rounded Pages to prevent connections through a passivation layer. This is in particular a measure in addition to a possible passivation layer on one or both ends.

According to yet another embodiment, the passivation layer an axial length of 5 mm to 50 mm. This allows an exact alignment of the housing to the respective application. Is the case, for example arranged or diverge relatively close to an internal combustion engine thermal expansion behavior of honeycomb body and jacket tube is very strong the passivation layer is made with a larger axial length.

It is particularly advantageous, the passivation layer with a thickness of 0.03 mm to 0.12 mm. This allows in particular the compensation of Manufacturing tolerances of honeycomb body and casing pipe in the assembled Status.

According to a further embodiment is between the jacket tube and the ceramic Layer an adhesive layer arranged. This is especially advantageous when the ceramic layer is exposed to a high dynamic load is. The adhesive layer allows a permanent connection of the ceramic Layer on the metallic surface of the jacket tube.

It is particularly advantageous before assembly with a honeycomb body the passivation layer of the jacket tube to arrange a solder layer. The passivation layer Although prevents the formation of solder joints between Honeycomb body and jacket tube. But if the honeycomb body, for example, from a variety of sheet metal layers produced by winding and / or stacking, so may be soldered by the solder disposed on the passivation layer adjacent ends of the sheet metal layers are guaranteed to each other. To this Way fluttering of end portions of the sheet metal layers is avoided and the life of such a honeycomb body increases. In particular, the training a circumferential solder layer on the passivation layer has the consequence that all adjacent sheet metal layers are soldered together.

According to another inventive idea, is a catalyst carrier body with a housing according to the invention and a honeycomb body arranged therein executed. The honeycomb body is made of sheet metal layers, at least partially are structured so that the honeycomb body for a exhaust gas flow through channels having. The jacket tube encloses the honeycomb body at least partially and is in at least one axial portion with the honeycomb body joining technology connected is. The selective fiigetechnische connection of honeycomb body and Jacket tube ensures a long life of the catalyst carrier body.

It is particularly advantageous, the ceramic layer near an end face of the To arrange honeycomb body. In an orientation of the catalyst carrier body in an exhaust system, wherein the portion with the ceramic layer for hot exhaust gas (upstream) is aligned compensated for the catalyst carrier body especially good the high thermal stress.

According to a further embodiment are radially outer end portions the sheet layers of the honeycomb body to the ceramic layer. The flutter This radially outer end portions can thus be reduced. Especially It is advantageous, joining the adjacent end areas together connect to. This ensures a long life even at extreme dynamic Loads safely.

According to a further embodiment of the honeycomb body with the jacket tube soldered, preferably high-temperature vacuum-soldered.

Ausgehend von der Herstellung eines Mantelrohres wird anschließend eine Passivierungsschicht an der Innenwandung des Mantelrohres in mindestens einem Abschnitt ausgebildet. In diesem Abschnitt wird eine Lötverbindung von Mantelrohr und Wabenkörper bei einem später folgenden Lötprozeß verhindert. Bevorzugt ist dieser Abschnitt nahe einer Stirnfläche des Wabenkörpers im eingebrachten Zustand angeordnet. Anschließend erfolgt das Beloten der Innenwandung des Mantelrohres.

According to a further aspect of the invention, a method for producing a catalyst carrier body with a honeycomb body and a jacket tube is proposed. The honeycomb body is made of sheet metal layers which are at least partially structured such that the honeycomb body has channels through which an exhaust gas can flow. The jacket tube has an inner wall which at least partially encloses the honeycomb body and which is soldered in at least one axial portion with the honeycomb body. The jacket tube has in at least a portion of the inner wall on a passivation layer for selectively preventing a solder joint with the honeycomb body. The manufacturing process comprises the following steps:

Starting from the production of a jacket tube, a passivation layer is subsequently formed on the inner wall of the jacket tube in at least one section. In this section, a solder joint of jacket tube and honeycomb body is prevented in a subsequent subsequent soldering process. Preferably, this portion is arranged near an end face of the honeycomb body in the inserted state. Subsequently, the Beloten the inner wall of the jacket tube.

The honeycomb body is in a known manner by stacking and / or winding of Formed sheet metal layers which are at least partially structured so that the honeycomb body having flowed through for an exhaust gas channels. The honeycomb body becomes now introduced into the jacket tube. Thereafter, the solder joints are formed. In this way, a catalyst carrier body can be produced, which on the one hand by a permanent connection of honeycomb body and Jacket tube distinguishes, on the other hand, but also a balance different Strain behavior. of honeycomb body and casing pipe permits. Thereby arise in the soldering process no vapors or gases, which is a formation of solder joints, especially in a vacuum.

According to one embodiment of the method, the passivation layer is through generates selective, spatially limited heating of the at least one section. The portion of the housing is therefore heated to a temperature and possibly also held on this to diffusion processes in the material and to allow on the inner wall of the housing. Suitable in this regard in particular ferritic, aluminum and chromium containing materials which be heated to a temperature above 1100 ° C. This will get metal particles, in particular aluminum from the interior to the vicinity of the inner wall of the jacket tube, which now with the oxygen particles from the environment too react to the desired passivation layer. The passivation layer can Consequently, be produced without a filler material.

It is particularly advantageous to heat the at least one section to achieve by inductive heating. With the inductive heating method generates spatially limited eddy currents, which due to the electrical material resistance lead to a warming of the section. Besides the fact that with the inductive heating to limit the surface to be heated well This process is faster for high volume production Clock sequence suitable.

According to yet another embodiment of the method, the at least a section in the preparation of the passivation layer with an oxygen-containing Gas flows. In this way, a rich on the inner wall Supply of oxygen molecules ensures that in the formation of a Surface oxide layer may be needed. As a result, the generation of a Passivation layer very favored.

It is particularly advantageous, the jacket tube outside the at least one Section in the preparation of the passivation layer with a noble gas, in particular Argon, to flow. The noble gas prevents the formation of the Oxide layer, because the noble gas does not react with the metal particles of the jacket tube and displaced the atmospheric oxygen.

According to a further embodiment of the method is proposed, the passivation layer by a chemical treatment of the at least one section manufacture. For this purpose, the section with a chemical treated, which leads to the formation of a surface oxide layer. This Process step is particularly suitable for cased pipes, with very small Manufactured manufacturing tolerances with respect to the male honeycomb body were. A thermal treatment without the honeycomb body and thus a thermal Delay can be prevented.

According to a further embodiment of the method, the passivation layer by applying a ceramic coating layer, in particular aluminum oxide, produced.

According to a further advantageous embodiment of the method is before Forming the ceramic layer on the relevant section of the inner wall the cladding tube applied an adhesive layer. This leads to a special stable connection of the ceramic layer with the jacket tube. This adhesive layer preferably has no volatile components to a to ensure a secure soldering process.

It is particularly advantageous for the ceramic layer by means of flame spraying form the jacket tube. The flame spraying is characterized by a special uniform distribution of the ceramic layer on the inner wall of the Jacket tube off, causing pressure peaks in the jacket tube due to the adjacent Metal layers are avoided.

According to a further embodiment of the method is before the Beloten the Inner wall of the jacket tube, in particular on the ceramic layer, applied an adhesive medium for producing a solder layer. The adhesive medium has the task to fix the solder powder at the points of the jacket tube to which a solder joint should be executed during the later soldering process. The Adhesive medium on the ceramic layer thereby ensures the arrangement of solder powder in the region of the honeycomb body in which a compound is undesirable with the jacket tube. This solder layer is used for later soldering adjacent metal layers of the honeycomb body with each other.

According to a further embodiment of the method is during or after the Inserting the honeycomb body in the jacket tube on the honeycomb body end face Lot powder applied. In this way, the end portions of the sheet metal layers soldered together near the front and the life of such a manufactured Catalyst carrier body increased.

According to yet another embodiment of the method, the passivation layer by roughening the inner wall in the at least one section produced. It is particularly advantageous roughening with the manufacturing process Sandblasting and / or brushing takes place. Surprisingly prevented the resulting roughness of the inner wall wetting by a Lotmittel in this section, with a technical connection between Honeycomb body and jacket tube is prevented. Thus, a particularly inexpensive produced passivation layer specified.

Further details of the catalyst support body according to the invention and a Process for its preparation are based on the illustrated in the drawing particularly preferred embodiments explained.

Fig. 1

eine perspektivische Darstellung von Mantelrohr und Wabenkörper eines erfindungsgemäßen Katalysator-Trägerkörpers;

Fig. 2

eine stimseitige Ansicht einer gefügten Ausführungsfonn eines erfindungsgemäßen Katalysator-Trägerkörpers;

Fig. 3

eine schematische Darstellung des Schichtaufbaus bei einem erfindungsgemäßen Gehäuse;

Fig. 4

eine perspektivische Darstellung einer Ausführungsform eines ovalen Gehäuses mit Wabenkörper und Passivierungsschicht.

Show it:

Fig. 1

a perspective view of casing and honeycomb body of a catalyst support body according to the invention;

Fig. 2

an end view of a joined Ausführungsfonn a catalyst support body according to the invention;

Fig. 3

a schematic representation of the layer structure in a housing according to the invention;

Fig. 4

a perspective view of an embodiment of an oval housing with honeycomb body and passivation layer.

Fig. 1 shows a honeycomb body 4 with an end face 12. The honeycomb body has several sheet metal layers 9 produced by winding and / or stacking on the honeycomb body 4 is introduced into a jacket tube 1. The jacket tube 1 has an inner wall 2, which has a section 14 with a passivation layer 3 having. The portion 14 has a length 5, wherein the portion 14 in the joined Condition of the catalyst carrier body near the end face 12 of the honeycomb body 4 is arranged. On the section 14, a solder layer 7 is additionally shown.

After the honeycomb body 4 has been introduced into the jacket tube 1, this is done Forming the solder joints. The honeycomb body 4 is then in the partial area 11 connected to the jacket tube 1 joining technology. The passivation layer 3 prevented in section 14, a compound of the honeycomb body 4 with the jacket tube 1, so that in this section 14, the different thermal expansion behavior can be compensated. The solder layer 7 ensures that the Sheet metal layers 9 are connected together.

Fig. 2 shows an end view of the catalyst carrier body according to the invention. The jacket tube 1 encloses a plurality of sheet metal layers 9, wherein these rest with their end portions 13 on the casing tube 1. The sheet metal layers have corrugated and smooth sheets 16, which are arranged so in that through-flow channels 10 are formed for an exhaust gas.

Fig. 3 shows schematically the structure of a housing according to the invention for a Honeycomb body, wherein the arrangement of different layers (3, 6, 7) in the section 14 of the jacket tube 1 is shown. On the inner wall 2 of the jacket tube 1, an adhesive layer 6 is arranged, which provides a permanent connection of the Passivation layer 3 on the casing tube 1 ensures. The passivation layer 3 has a thickness 8, which according to the requirements of the catalyst carrier body is variable. On the passivation layer 3 is additionally a solder layer 7, which shows a connection of adjacent end regions 13 of FIG Sheet metal layers 9 ensures.

4 shows a perspective and schematic illustration of an embodiment an oval casing tube 1 with honeycomb body 4 and passivation layer 3. The honeycomb body has several generated by winding and / or stacking Sheet metal layers 9, which are at least partially structured so that they are suitable for an exhaust gas can flow through. The honeycomb body 4 has a plurality of channels 10, which are bounded by smooth and / or corrugated sheets 16 and is of Enclosed the jacket tube 1. The jacket tube 1 has an inner wall. 2 auf, which in a jacket pipe section 17 with a passivation layer. 3 is executed. The sheath portion area 17 is the more curved area of the oval or elliptical jacket tube 1, according to experience a solder joint unfavorable.

A catalyst carrier body produced according to the invention makes it possible to compensate different expansion behavior of honeycomb body and casing pipe, wherein this preparation of such a catalyst support body a secure Soldering guaranteed, especially in the high-temperature vacuum brazing process.

LIST OF REFERENCE NUMBERS

1

casing pipe

2

inner wall

3

passivation

4

honeycombs

5

length

6

adhesive layer

7

solder layer

8th

thickness

9

sheet metal layer

10

channel

11

subregion

12

face

13

end

14

section

15

adhesive medium

16

sheet

17

Casing section

Claims (28)

1. A housing for a metallic honeycomb body (4) comprising a metallic jacket tube (1) with an inner wall (2), characterized in that, in order deliberately to prevent connection to a metallic honeycomb body (4) by joining, the jacket tube (1) has a passivation layer (3) in at least one section (14) of the inner wall (2).
2. The housing as claimed in claim 1, characterized in that the passivation layer (3) is in the form of an oxide surface layer.
3. The housing as claimed in claim 1, characterized in that the passivation layer (3) is embodied as an applied ceramic layer, involving aluminum oxide in particular.
4. The housing as claimed in one of claims 1 to 3, characterized in that the passivation layer (3) is designed as an all-round strip.
5. The housing as claimed in one of claims 1 to 3, the jacket tube (1) being oval or elliptical, characterized in that the passivation layer (3) is arranged in a more sharply curved jacket-tube section (17).
6. The housing as claimed in one of claims I to 5, characterized in that the passivation layer (3) has an axial length (5) of 5 mm to 50 mm.
7. The housing as claimed in one of claims 1 to 6, characterized in that the passivation layer (3) has a thickness (8) of 30 µm to 120 µm.
8. The housing as claimed in one of claims 1 to 7, wherein the passivation layer (3) is embodied as a ceramic layer, characterized in that an adhesive layer (6) is arranged between the jacket tube (1) and the applied ceramic layer (3).
9. The housing as claimed in one of claims 1 to 8, characterized in that a layer (7) of brazing material is arranged on the passivation layer (3).
10. The housing as claimed in claim 9, characterized in that the layer (7) of brazing material is formed as an all-round layer on the passivation layer (3).
11. A catalyst support structure with a housing as claimed in one of claims 1 to 10 and with a honeycomb body (4) comprising sheet metal layers (9) that are at least in part structured in such a way that the honeycomb body (4) has passages (10) through which an exhaust gas can flow, the jacket tube (1) at least partially surrounding the honeycomb structure (4) and being connected to the honeycomb body (4) by joining in at least one axial partial area (11).
12. The catalyst support structure as claimed in claim 11, characterized in that the passivation layer (3) is arranged close to an end face (12) of the honeycomb body (4).
13. The catalyst support structure as claimed in claim 11 or 12, characterized in that radially outer end regions (13) of the sheet metal layers (9) of the honeycomb body (4) rest against the passivation layer (3).
14. The catalyst support structure as claimed in claim 13, characterized in that the end regions (13) resting against the passivation layer (3) are connected to one another by a joining technique.
15. The catalyst support structure as claimed in one of claims 11 to 14, characterized in that the honeycomb body (4) is brazed to the jacket tube (1), preferably by high-temperature vacuum brazing.
16. A method for the production of a catalyst.support structure having a honeycomb body (4) comprising sheet metal layers (9) that are at least in part structured in such a way that the honeycomb body (4) has passages (10) through which an exhaust gas can flow, having a jacket tube (1) with an inner wall (2) that at least partially surrounds the honeycomb body (4) and is brazed to the honeycomb body (4) in at least one axial partial area (11), the jacket tube (1) being provided with a passivation layer (3) in at least one section (14) of the inner wall (2) for deliberate prevention of a brazed joint with the honeycomb body (4), characterized by the following steps:

    production of a jacket tube (1);

    formation of a passivation layer (3) on the inner wall (2) of the jacket tube (1) in at least one section (14), in which a brazed joint between the jacket tube (1) and the honeycomb body (4) is to be prevented;

    supplying at least partial areas of the inner wall (2) of the jacket tube (1) with brazing material;

    formation of the honeycomb body (4) in a known manner by stacking and/or winding sheet metal layers (9), which are at least in part structured in such a way that the honeycomb body (4) has passages (10) through which an exhaust gas can flow;

    introduction of the honeycomb body (4) into the jacket tube (1);

    formation of the brazed joints.
17. The method as claimed in claim 16, the passivation layer (3) being produced by selective, spatially limited heating of the at least one section (14).
18. The method as claimed in claim 17, characterized in that the heating of the section (14) is carried out inductively.
19. The method as claimed in one of claims 16 to 18, characterized in that the at least one section (14) is supplied with a stream of oxygen-containing gas during the production of the passivation layer (3).
20. The method as claimed in one of claims 16 to 19, characterized in that the jacket tube (1) is supplied with a stream of a noble gas, in particular argon, outside the at least one section (14) during the production of the passivation layer (3).
21. The method as claimed in claim 16, characterized in that the passivation layer (3) is produced by chemical treatment of the at least one section (14).
22. The method as claimed in claim 16, characterized in that the passivation layer (3) is produced by applying an applied ceramic layer, in particular aluminum oxide, to the at least one section (14) of the inner wall (2).
23. The method as claimed in claim 22, characterized in that an adhesive layer (6) is applied to the at least one section (14) before the formation of the applied ceramic layer.
24. The method as claimed in claim 22 or 23, the passivation layer (3) being embodied as an applied ceramic layer that is formed on the jacket tube (1) by flame spraying.
25. The method as claimed in one of claims 16 to 24, in which, to produce a layer (7) of brazing material, an adhesive is applied, in particular to the passivation layer (3), before the inner wall (2) of the jacket tube (1) is supplied with brazing material.
26. The method as claimed in one of claims 16 to 25, wherein powdered brazing material is applied at the end face (12) of the honeycomb body (4) during or after the introduction of the honeycomb body (4) into the jacket tube (1).
27. The method as claimed in claim 16, wherein the passivation layer (3) being produced by roughening the inner wall (2) in the at least one section (14).
28. The method as claimed in claim 27, wherein roughening being performed by the production methods of sandblasting and/or brushing.

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