CATALYST BODY, ELECTRICALLY HEATED CATALYST, MOTOR VEHICLE WITH CATALYST AND METHOD FOR PRODUCING A CATALYST

Abstract

An electrically heated catalyst has a catalyst body and a housing at least circumferentially surrounding the catalyst body. An electrical contacting assembly is arranged on a shell surface of the catalyst body, the electrical contacting assembly comprising a surface electrode arranged directly on the catalyst body and a contacting element connected to the surface electrode. The contacting element is rigid and has a screw thread.

Claims

1. A catalyst body for an electrically heated catalyst: at least one electrical contacting assembly arranged on a shell surface of the catalyst body, the at least one electrical contacting assembly comprising a surface electrode arranged directly on the catalyst body and a rigid contacting element connected to the surface electrode, wherein the contacting element has a screw thread.

2. The catalyst body according of claim 1 wherein the rigid contacting element is arranged directly on the surface electrode.

3. The catalyst body according of claim 1 wherein the catalyst body has a depression and the rigid contacting element is arranged in the depression in such a way that the rigid contacting element does not protrude beyond an outer surface of the catalyst body.

4. The catalyst body of claim 1 wherein the rigid contacting element is adhered to the surface electrode.

5. The catalyst body of claim 1 wherein the rigid contacting element is secured to a contact element, in particular a flexible contact element, wherein the flexible contact element is arranged on the surface electrode.

6. The catalyst body of claim 1 wherein the rigid contacting element is a nut.

7. An electrically heated catalyst with the catalyst body of claim 1 and a housing at least circumferentially surrounding the catalyst body, and wherein a screw is screwed into the rigid contacting element for electrically contacting the electrically heated catalyst.

8. The electrically heated catalyst of claim 7 wherein the rigid contacting element is arranged completely inside the housing.

9. The electrically heated catalyst of claim 7 wherein at least one opening is provided in the housing, wherein the at least one opening is arranged over the rigid contacting element in such a way that the rigid contacting element is accessible via the at least one opening.

10. The electrically heated catalyst of claim 9 wherein a cover is arranged over the at least one opening, in particular wherein the cover is held on the catalyst body by the screw.

11. The electrically heated catalyst of claim 7 wherein the catalyst body is surrounded by an insulating mat.

12. A motor vehicle with the electrically heated catalyst of claim 7.

13. A method for producing the electrically heated catalyst as defined in claim 7, comprising the following steps: providing the catalyst body as a cylindrical catalyst body, wherein the at least one electrical contacting assembly with the rigid contacting element is arranged on the shell surface of the catalyst body, the catalyst body is wrapped into an insulating mat, wherein the insulating mat comprises openings and wherein the insulating mat is arranged in such a way that the rigid contacting element is not covered by the insulating mat, the catalyst body is encased, with the insulating mat, in a housing, the housing having at least one opening which is aligned in such a way that the rigid contacting element is accessible via the at least one opening, and once the catalyst body is encased, the rigid contacting element is electrically contacted.

14. A method for producing the electrically heated catalyst as defined in claim 7, comprising the following steps: providing the catalyst body as a cylindrical catalyst body, wherein at least one surface electrode is arranged on the shell surface of the catalyst body, the catalyst body is wrapped in an insulating mat, wherein the insulating mat comprises at least one opening and wherein the insulating mat is arranged in such a way that the at least one surface electrode is partially exposed, the catalyst body is encased, with the insulating mat, in a housing, wherein the housing has at least one opening which is aligned in such a way that the at least one opening of the insulating mat and the at least one opening of the housing lie one on top of the other, and once the catalyst body is encased, a contact element is secured to the surface electrode, wherein the rigid contacting element with the screw thread is arranged on the contact element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Further advantages and features of the invention emerge from the following description and the following drawings, to which reference is made. In the drawings, there are shown in:

[0031] FIG. 1, schematically, a first embodiment of a catalyst according to the invention,

[0032] FIGS. 2 and 3, schematically, in each case a further embodiment of a catalyst according to the invention, and

[0033] FIG. 4 a catalyst body with a surface electrode.

DETAILED DESCRIPTION

[0034] FIG. 1 schematically shows an electrically heated catalyst 10 with a catalyst body 12, which is circumferentially surrounded by an insulating mat 14, and a housing 16. The catalyst body 12 is held in the housing 16 via the insulating mat 14.

[0035] The catalyst body 12 is, for example, a honeycomb body, in particular made of ceramic or of metal.

[0036] A contacting assembly 18, which comprises a surface electrode 20 and a contacting element 22, is provided on a shell surface of the catalyst body 12. The surface electrode 20 is arranged directly on the shell surface of the catalyst body 12.

[0037] In the embodiment example shown, the surface electrode 20 is formed by an electrode paste, for example by a silver paste.

[0038] The contacting element 22 is rigid and has a screw thread. In particular, the screw thread is a female thread. In the embodiment shown, the contacting element 22 is a nut.

[0039] For electrically contacting the electrically heated catalyst 10, a screw 24 is screwed into the screw thread. When screwing the screw 24 into the screw thread, the screw-in-direction is transverse, in particular perpendicular to a longitudinal axis of the catalyst body 12.

[0040] The screw 24 is connected to an electrical wire which is not represented in the figures for the sake of simplicity. For example, a cable lug which is threaded over the screw 24 is provided on the wire.

[0041] As is seen in FIG. 1, the contacting element 22 is arranged completely inside the housing 16. The housing 16 is spaced apart from the contacting element 22 in the radial direction. The catalyst body 12 can thus be pushed into the housing 16 together with the insulating mat 14, without the contacting element 22 colliding with the housing 16.

[0042] For example, the catalyst body 12 is wrapped in the insulating mat 14 and pushed into the housing 16 together with the insulating mat 14. Alternatively or additionally, the housing 16 can then be compressed by a pressing tool in order to improve the seat of the catalyst body 12 in the housing 16.

[0043] The thickness of the insulating mat 14 is greater than the height of the contacting element 22 on the catalyst body 12. The insulating mat 14 can thereby be compressed a little during the pressing process in order to make it easier to insert the catalyst body 12 into the housing 16.

[0044] In order to guarantee the accessibility of the contacting element 22, the insulating mat 14 comprises at least one opening 26. During the wrapping of the catalyst body 12, the insulating mat 14 is arranged in such a way that the contacting element 22 is not covered by the insulating mat 14.

[0045] The housing 16 likewise has at least one corresponding opening 28 which is aligned in such a way that the contacting element 22 is accessible via the opening 28.

[0046] Due to the screw thread being a female thread, the size of the opening 28 may be relatively small. In particular, an area surrounding the contacting element 22 does not need to be accessible and may be covered by the housing 16.

[0047] According to a further embodiment, which for reasons of simplicity is not illustrated in the figures, the size of the opening 28 may be equal to or smaller than the size of the contacting element 22 in a plan view on the opening 28, which corresponds to a side view on the catalyst body 12. In other words, the housing 16 may overlap with the contacting element 22 in a plan view on the opening 28.

[0048] The openings 28 in the housing 16 are closed with a cover 30. The cover 30 is, for example, a plastic cap.

[0049] As shown in FIG. 1, the cover 30 is secured with the screw 24 which is at the same time screwed into the contacting element 22 for the contacting. Thus, no additional components are necessary to secure the cover 30.

[0050] In order to achieve a gas-tight seal of the openings 28, a seal 34, for example a sealing ring, is arranged in each case between the housing 16 and the cover 30, and between the cover 30 and the screw head 32 of the screw 24.

[0051] FIG. 2 schematically shows a further embodiment of an electrically heated catalyst 10 according to the invention.

[0052] This embodiment differs from the embodiment according to FIG. 1 in that the catalyst body 12 has a depression 36 and the contacting element 22 is arranged in the depression 36 in such a way that the contacting element 22 does not protrude beyond an outer surface of the catalyst body 12. The catalyst 10 is thereby particularly compact. The screw 24 is not represented in FIG. 2 for the sake of simplicity.

[0053] FIG. 3 schematically shows a further embodiment of the electrically heated catalyst 10 according to the invention.

[0054] A surface electrode 20 made of a metal plate 38 is illustrated in this representation, instead of the surface electrode 20 made of an electrode paste illustrated in FIG. 1. The metal plate 38 is, for example, adhered to the catalyst body 12.

[0055] A catalyst body 12 with a corresponding surface electrode 20 is represented in detail in FIG. 4.

[0056] The embodiment according to FIG. 3 in addition differs from the embodiments represented in FIGS. 1 and 2 in that the contacting element 22 is not arranged directly on the surface electrode 20, but a contact element 40 is provided, which is arranged on the surface electrode 20 and to which the contacting element 22 is secured. The contact element 40 is preferably flexible, for example made of a bendable sheet.

[0057] The contact element 40 can already be secured to the catalyst body 12, in particular to the surface electrode 20, before the catalyst body 12 is installed in the housing 16.

[0058] Alternatively, the contact element 40 can be secured to the surface electrode 20 after the catalyst body 12 has been installed in the housing 16. For example, the contact element 40, together with the contacting element 22 secured to the contact element 40, is welded to the surface electrode 20, in particular by laser welding.

[0059] All described embodiments of an electrically heated catalyst 10 according to the invention have in common the fact that, despite the presence of a lateral contacting assembly 18 of the catalyst body 12, an easy installation of the catalyst body 12 in the housing is possible.

[0060] During the installation, the catalyst body 12 is firstly wrapped in the insulating mat 14, wherein the insulating mat 14 is arranged in such a way that the contacting element 22 is not covered by the insulating mat 14.

[0061] Then, the catalyst body 12 is encased, together with the insulating mat 14, in the housing 16, wherein the opening 28 is aligned in such a way that the contacting element 22 is accessible via the opening 28. In this method step, the insulating mat 14 is preferably compressed a little.

[0062] Once the catalyst body is encased, the contacting element 22 is electrically contacted.

[0063] The contacting element 22 can already be secured to the catalyst body 12 before the encasing or, as described in connection with FIG. 3, can be attached to the catalyst body 12 after the encasing, for example by the contact element 40 welded to the surface electrode 20.

[0064] Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. For that reason, the following claims should be studied to determine the true scope and content of this disclosure.