Electrically heatable heating disk for exhaust gas aftertreatment

Abstract

A heating disk for heating up a stream of exhaust gas and/or a component for exhaust gas aftertreatment has a honeycomb body, wound from a plurality of smooth and corrugated metal layers stacked on top of one another. The honeycomb body is received within a carrier shell and an electrical contact is fed through the carrier shell. The honeycomb body is connected to a current source via the electrical contact. The electrical contact has a contact strip within the carrier shell extending in the circumferential direction of the carrier shell. An insulating region is formed between the carrier shell and the contact strip. A plurality of stacks of layers are electrically insulated from one another. Each of the stacks of layers are formed from the plurality of smooth and corrugated metal layers, and which are arranged directly adjacent to one another and conductively connected to the contact strip.

Claims

1. A heating disk for heating up a stream of exhaust gas comprising: a carrier shell; a plurality of smooth and corrugated metal layers stacked on top of one another to form a plurality of stacks of layers; a honeycomb body wound from the plurality of smooth and corrugated metal layers and located within the carrier shell; an electrical contact structure extending through a feedthrough defined by the carrier shell and via which the honeycomb body can be connected to a current source; a contact strip of the electrical contract structure located in a region enclosed by the carrier shell and extending in the circumferential direction of the carrier shell; an insulating region formed between the carrier shell and the contact strip; a radially outwardly extending bulge formed as part of the carrier shell, the contact strip and the insulating region received into the radially outwardly extending bulge; wherein each of the plurality of stacks of layers are electrically insulated from one another, arranged directly adjacent to one another, and connected electrically conductively to the contact strip, wherein each are formed from the plurality of smooth metal layers and corrugated metal layers.

2. The heating disk as claimed in claim 1, wherein the insulating region is formed by one of: an air gap and ceramic insulation.

3. The heating disk as claimed in claim 1, wherein the contact strip is electrically conductively connected to up to three of the plurality of stacks of layers, which are otherwise electrically insulated from one another.

4. The heating disk as claimed in claim 1, wherein up to five of the plurality of stacks of layers each have up to seven corrugated metal layers and up to eight smooth metal layers.

5. The heating disk as claimed in claim 4, wherein there are three stacks of layers.

6. The heating disk as claimed in claim 1, wherein the contact strip extends in the circumferential direction of the carrier shell, and a partial region of the contact strip is angled in relation to the central axis of the honeycomb body.

7. The heating disk as claimed in claim 6, wherein the resonant frequency of the angled region is in a range outside the oscillation frequencies of the exhaust system.

8. The heating disk as claimed in claim 7, wherein the that the resonant frequency of the angled region is above 2500 Hz.

9. The heating disk as claimed in claim 1, wherein the feedthrough has a cross section that tapers conically from the outside inward.

10. The heating disk as claimed in claim 1, wherein the electrical contact structure is formed by an inner conductor inserted in a receiving sleeve penetrating the carrier shell, wherein the inner conductor is spaced apart from the receiving sleeve by an electrically insulating layer.

11. The heating disk as claimed in claim 10, wherein at least one of: the inner conductor and the receiving sleeve have a conically tapering cross section.

12. The heating disk as claimed in claim 10, wherein the contact strip is connected to the inner conductor, receiving sleeve, and insulating layer that form the electrical contact structure and are fed through the carrier shell and the contact strip is positioned relative to the carrier shell by the inner conductor, receiving sleeve, and insulating layer.

13. The heating disk as claimed in claim 1, wherein the contact strip has a mechanically fixed but electrically insulating connection to the carrier shell with at least one of metal or ceramic soldered connection.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be explained in detail in the following text on the basis of exemplary embodiments with reference to the drawings, in which:

(2) FIG. 1 shows a schematic sectional view through a heating disk according to the invention with a feedthrough for an electrical contact structure and a contact strip for connecting a number of stacks of layers;

(3) FIG. 2 shows a sectional view through a feedthrough with an inner conductor, which is used to introduce an electrical current into the stacks of layers; and

(4) FIG. 3 shows a further schematic sectional view through a heating disk, wherein the contact strip has an angled region.

DETAILED DESCRIPTION

(5) FIG. 1 shows a sectional view through a heating disk 1. The heating disk 1 is formed from a plurality of stacks of layers 2, which in turn are formed from smooth metal layers and corrugated metal layers stacked one on top of the other. The stacks of layers 2 are electrically insulated from one another by an air gap 3, so that the current cannot flow from one stack of layers 2 to the next.

(6) The stacks of layers 2 are connected at the end to a contact strip 4. The contact strip 4 is for its part connected to an electrical conductor, not shown in FIG. 1, which is fed through the feedthrough 5 into the heating disk 1.

(7) The wound-up stacks of layers 2 and the contact strip 4 are arranged within a carrier shell 6, which encompasses the heating disk 1 formed by the stacks of layers 2 and gives it the necessary stability.

(8) The electrical current is transmitted through the feedthrough 5 to the contact strip 4 and flows through the stacks of layers 2 along the arrows 7. In the exemplary embodiment in FIG. 1, two stacks of layers 2 are electrically conductively connected to the contact strip 4. The two stacks of layers 2 are therefore uniformly subjected to the current flowing through the feedthrough 5. The electrical insulation of the stacks of layers 2 from one another also ensures that in each case the current only flows along the respective stacks of layers 2 and does not flow uncontrollably into adjacent stacks of layers 2. This ensures that there are no shortened current flow paths that can lead to an inhomogeneous temperature distribution, and thus adversely affect the efficiency of the heating disk 1.

(9) The carrier shell 6 has a radially outwardly directed bulge 8. This bulge 8 serves for receiving the contact strip 4 and possibly an insulating region 9. The bulge 8 is preferably such that the contact strip 4 can be completely received in it, and thus the entire cross-sectional area enclosed by the carrier shell 6 can be used for the wound-up stacks of layers 2 or the heating disk 1 formed from them.

(10) Depending on the design, the insulating region 8 may be formed by a layer of air in which the contact strip 4 is arranged at a sufficient distance from the carrier shell 6, or by a ceramic material layer. The contact strip 4 is preferably supported with respect to the carrier shell 6, and possibly also connected to it, by the ceramic insulating layer. This increases the strength and durability of the heating disk.

(11) The feedthrough 5 may be welded or soldered to the carrier shell 6 in order to ensure a permanent hold.

(12) FIG. 2 shows a sectional view through a feedthrough 10, as it has already been indicated in FIG. 1 by reference numeral 5.

(13) The feedthrough 10 has an inner conductor 11, which leads through a receiving sleeve 12 connected to the carrier shell to the contact strip 13. Arranged between the receiving sleeve 12 and the inner conductor 11 is an insulating layer 14, which creates an electrical insulation with respect to the carrier shell.

(14) The contact strip 13 and the inner conductor 11 may be welded or soldered to one another.

(15) The exemplary embodiment in FIG. 2 shows an inner conductor 11 and a receiving sleeve 12, each of which has a cross section that tapers conically inward. By pushing the inner conductor 11 into the receiving sleeve 12, a pressing effect is thus produced between the inner conductor 11 and the receiving sleeve 12.

(16) Such a design of the receiving sleeve 12 and the inner conductor 11 also ensures that the contact strip 13 is held securely in its position, since the inner conductor 11 cannot slip into the inner region of the carrier shell due to the conical design.

(17) FIG. 3 shows an alternative design of the contact strip 20 in a construction that otherwise corresponds to that of FIG. 1. In FIG. 3, for the sake of simplicity the contact strip 20 is only connected to one stack of layers 21. However, the connection of a number of stacks of layers that are electrically insulated from one another is possible.

(18) The contact strip 20 has an angled region 24, which is bent radially inward away from the carrier shell 22. Thus, the distance between the carrier shell 22 and the contact strip 20 is increased, as a result of which an improved electrical insulation may be achieved, even if no electrically insulating layer, such as for example a ceramic layer, is provided.

(19) The contact strip 20, and in particular the angled region 24, may be designed with regard to the material selection and the dimensioning in particular in such a way that the natural frequency of the contact strip 20 lies outside the frequency spectrum of the vibrations in an exhaust system of a motor vehicle in order to avoid resonance phenomena.

(20) The foregoing preferred embodiments have been shown and described for the purposes of illustrating the structural and functional principles of the present invention, as well as illustrating the methods of employing the preferred embodiments and are subject to change without departing from such principles. Therefore, this invention includes all modifications encompassed within the scope of the following claims.