ELECTRICALLY HEATABLE CATALYTIC CONVERTER

Abstract

An electrically heatable catalytic converter with a metal honeycomb body, the honeycomb body being formed by a plurality of wound metal foils and the honeycomb body being received in a casing tube, a device for electrically contacting at least individual foils being led into the casing tube through an opening in the casing tube, the device being formed by an electrode which is electrically insulated from the inside of the casing tube by a connecting layer and mechanically connected to the casing tube.

Claims

1. An electrically heatable catalytic converter, comprising: a honeycomb body formed by a plurality of wound metal foils; a casing tube, the honeycomb body being received in the casing tube; an opening formed as part of the casing tube; a device for electrically contacting at least one of the plurality of wound metal foils, the device further comprising: an electrode which is mechanically connected to the casing tube and is electrically insulated from the inside of the casing tube by a connecting layer; wherein the device is led into the casing tube through the opening in the casing tube.

2. The electrically heatable catalytic converter of claim 1, wherein at least one of the plurality of wound metal foils forming the honeycomb body are electrically conductively connected to the electrode.

3. The electrically heatable catalytic converter of claim 1, the connecting layer further comprising: an insulating layer; and an adhesive layer, the insulating layer facing the casing tube and the adhesive layer facing the electrode.

4. The electrically heatable catalytic converter of claim 3, the insulating layer further comprising an electrically insulating effect.

5. The electrically heatable catalytic converter of claim 4, the insulating layer being one selected from the group consisting of Al.sub.2O.sub.3, ZrO.sub.2, MgO, TiO.sub.2, CeO.sub.2, a ceramic doped with yttrium, a ceramic doped with silicon, cordierite, mullite or a mixture of the materials listed.

6. The electrically heatable catalytic converter claim 3, the adhesive layer further comprising a metal layer.

7. The electrically heatable catalytic converter claim 6, the metal layer being formed from a material selected from the group consisting of Cu, Ni, Co, Ag, Pd or their alloys, such as for example AgPd or CuNi.

8. The electrically heatable catalytic converter of claim 3, wherein the insulating layer and the adhesive layer have similar coefficients of thermal expansion.

9. The electrically heatable catalytic converter of claim 3, wherein the opening in the casing tube is closed in a gas-tight manner by the material-bonding connection between the electrode, the insulating layer, and the adhesive layer.

10. The electrically heatable catalytic converter of claim 1, wherein the electrode is T-shaped and a section of the electrode arranged in the interior of the casing tube has a larger cross-sectional area than the opening.

11. The electrically heatable catalytic converter of claim 1, the casing tube further comprising: a radially outwardly directed bulge in the region of the opening; wherein a section of the electrode led into the interior of the casing tube being received in a pocket formed by the radially outwardly directed bulge.

12. The electrically heatable catalytic converter of claim 1, wherein the electrode is made in one piece.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The invention is explained in detail below on the basis of exemplary embodiments with reference to the drawings. In the drawings:

[0026] FIG. 1 shows a schematic sectional view through the electrode and the casing tube in the region of the lead-through through the casing tube, and

[0027] FIG. 2 shows a sectional view through the contact point between the casing tube and the electrode, the connecting layer also being shown.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

[0029] FIG. 1 shows a sectional view through a casing tube 1 of a catalytic converter, which in this embodiment is an electrically heatable catalytic converter. The casing tube 1 forms a housing for the honeycomb body 2 formed in the interior, which is formed from a plurality of metal foils which are stacked on top of one another to form stacks of layers 3.

[0030] The casing tube 1 has an opening 4 through which an electrode 5 is led. In the exemplary embodiment of FIG. 1, the electrode 5 has a stem-like extension, which protrudes outward through the opening 4 from the interior of the casing tube 1, and a plate-shaped section, which is arranged in the interior of the casing tube 1. The electrode 5 is T-shaped.

[0031] In the direct vicinity of the opening 4, the casing tube 1 has a bulge 6, in which the plate-shaped section of the electrode 5 is received. The inwardly directed surface of the plate-shaped section of the electrode 5 is in line with the inner wall of the casing tube 1. Depending on the radius of the casing tube 1, the plate-shaped section may also be preformed and adapted to the geometry of the inside of the casing tube 1. Thus, the electrode 5 may for example also be adapted to an oval or some other cross section of the casing tube 1.

[0032] The bulge 6 has the effect that an envelope curve placed around the honeycomb body 2 formed in the interior may have a continuous profile and need not have a notch or other recess in the region of the electrode 5. Honeycomb bodies are often produced by winding the stacks of layers around a mandrel or a number of mandrels.

[0033] The electrode 5 is mechanically and temperature-resistantly connected to the casing tube 1 by way of a connecting layer 7. The connecting layer 7 has an electrically insulating region 8 and an adhesive region 9. The electrically insulating region 8 is arranged on the side facing the casing tube 1 and the adhesive region is arranged on the side of the connecting layer 7 facing the electrode 5.

[0034] A solder 10, which is used for the later connection of the electrode 5 to the casing 1, may be applied to the adhesive region 9. The connecting layer 7 may be formed from two individual, joined-together layers. Alternatively, a layer which is formed differently in each of both edge regions may also be formed. For example, the concentration of added elements may vary in strength in order to achieve an electrically insulating effect at an edge region. A sufficiently high metal content to allow the connection to the electrode 5 by soldering may be formed at the opposite edge region. Various materials are also described.

[0035] The exemplary embodiment of FIGS. 1 and 2 does not have a restrictive character and serves for illustrating the concept of the invention.

[0036] The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.