ELECTRICALLY HEATABLE HONEYCOMB STRUCTURE HAVING CORRUGATED LAYERS OF DIFFERENT CELL DENSITY

Abstract

A honeycomb body for an electrically heatable exhaust gas tract catalytic converter, having a plurality of flow channels through which flow occurs along a main through flow direction formed from a plurality of metal foils stacked on one another to form a layer stack, which is wound around at least one pivot point. The layer stack has at least one first metal foil having a first corrugation and a second metal foil having a second corrugation. The first and the second metal foils form first and second corrugated layers. The honeycomb body has a plurality of winding layers, which are spaced apart from one another in the radial direction in the wound state by an air gap. The first corrugation is different from the second corrugation and the layer stack has at least three corrugated layers. The corrugated layers are separated from one another by a third metal foil.

Claims

1.-10. (canceled)

11. A honeycomb body for an electrically heatable catalytic converter in an exhaust gas tract, having a plurality of flow channels through which flow can occur along a main through flow direction, comprising: a plurality of metal foils stacked on one another to form a layer stack, which is wound around at least one pivot point, wherein the layer stack has: at least one first metal foil which has a first corrugation, at least one second metal foil which has a second corrugation, wherein the at least one first metal foil and the at least one second metal foil respectively form first and second corrugated layers, wherein the honeycomb body has a plurality of winding layers, which are spaced apart from one another in a radial direction of the honeycomb body in a wound state by an air gap, wherein the first corrugation is different from the second corrugation and the layer stack has at least three corrugated layers, wherein respective corrugated layers are each separated from one another by a smooth or microstructured third metal foil.

12. The honeycomb body as claimed in claim 11, wherein the at least one first metal foil has a lesser corrugation than the at least one second metal foil.

13. The honeycomb body as claimed in claim 11, wherein the corrugated layer which is formed from a first metal foil is used to accommodate support structures.

14. The honeycomb body as claimed in claim 11, wherein the corrugated layer which is formed from a second metal foil is configured to increase a rigidity of the honeycomb body.

15. The honeycomb body as claimed in claim 11, wherein the layer stack forming the honeycomb body has at least three corrugated layers, wherein at least one middle corrugated layer is formed by a first metal foil and at least the two corrugated layers forming radial edges of the layer stack are each formed by a second metal foil.

16. The honeycomb body as claimed in claim 11, wherein the layer stack forming the honeycomb body has precisely the three corrugated layers, wherein in succession a third metal foil, a second metal foil, a third metal foil, a first metal foil, a third metal foil, a second metal foil, and a third metal foil are arranged inside the layer stack.

17. The honeycomb body as claimed in claim 11, wherein each of the at least one second metal foils form a corrugated layer, which has a corrugation having greater wave height and/or greater wave width than the at least one corrugated layer formed by a first metal foil.

18. The honeycomb body as claimed in claim 15, wherein the corrugated layers forming a radial edge area of the layer stack generate a lower pressure loss for a fluid flowing through than the corrugated layers arranged in a center of the layer stack.

19. The honeycomb body as claimed in claim 11, wherein a cell density of the corrugated layers formed by the first metal foils is between 100 cpsi (cells per square inch) and 150 cpsi and the cell density of the corrugated layers formed by the second metal foils is between 25 cpsi and 80 cpsi.

20. The honeycomb body as claimed in claim 11, wherein at least one first group of the second metal foils is provided which has a ratio of wave height to wave width of less than 1.8 and/or at least one second group of the second metal foils is provided which has a ratio of wave height to wave width of greater than 1.8.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The invention will be discussed in detail below on the basis of an exemplary embodiment and with reference to the drawing. In the drawing:

[0036] The FIG. 1 is a view of a honeycomb body, wherein the flow channels formed by the honeycomb body extend along a surface normal to the plane of the drawing.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

[0037] The FIGURE shows a top view of a honeycomb body 1, which is formed from a layer stack 2 by winding. The layer stack 2 is supported by support pins 4 in relation to a catalytic converter 3 arranged behind it. The layer stack 2 is wound around two winding mandrels, due to which the layer stack 2 has an S-shaped course. The individual winding layers are spaced apart from one another in the radial direction by the air gap 11.

[0038] The layer stack 2 has a central corrugated layer which is formed from a first metal foil 7. This corrugated layer is enclosed by third metal foils 5, 10, which have a micro-structuring. Alternatively, a completely smooth third metal foil could also be provided.

[0039] The third metal foils 5, 10 are adjoined by two corrugated layers made of second metal foils 6, 9. The second metal foils 6, 9 have a somewhat greater wave height (pitch) and a substantially greater wave width, due to which the corrugated layers formed by the second metal foils 6, 9 have a lower cell density than the corrugated layer formed by the first metal foil 5, 10.

[0040] The second metal foils 6, 9 are each in turn adjoined by third metal foils 5, 10, which also have a micro-structuring and in alternative designs could also be formed by completely smooth metal foils.

[0041] The air gap 11 is used for electrically isolating the individual winding layers from one another and thus preventing short-circuits and undesired current conduction paths.

[0042] The exemplary embodiment in the FIGURE is in particular not of a limiting nature, and serves for illustrating the concept of one aspect of the invention.

[0043] Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.