Support structure for a heating matrix

Abstract

The heating matrix is made of a honeycomb body that has a plurality of flow channels through which exhaust gas can flow along a main flow direction, and the heating matrix is supported against the inner surface of the housing by the support structure (1). The matrix is fixed relative to the support structure (1) by means of a plurality of coupling elements (4), and the support structure (1) is formed in multiple parts, wherein the support structure (1) has at least one central ring-shaped element (3) and a plurality of braces (2) which protrude from the ring-shaped element (3) in the radial direction and run to the inner surface of the housing. All of the components are optionally connected using a joining method.

Description

[0001] Description

[0002] Support structure for a heating matrix

[0003] Technical area

[0004] The invention relates to a support structure for positioning a heating matrix in an exhaust gas path spatially delimited by a housing, wherein the heating matrix is ​​formed by a honeycomb body which has a plurality of flow channels through which flow can occur along a main flow direction, wherein the heating matrix is ​​supported relative to the inner surface of the housing by the support structure and the matrix is ​​fixed relative to the support structure by means of a plurality of coupling elements.

[0005] State of the art

[0006] Electric heating elements are now routinely used to heat exhaust gases in an exhaust system downstream of a combustion engine or the exhaust gas flowing through an exhaust system. The goal here is to more quickly reach a temperature threshold at which effective conversion of the pollutants carried in the exhaust can occur. This is necessary because the catalytically active surfaces of the catalysts installed in the exhaust system used for exhaust gas aftertreatment only allow sufficient conversion of the respective pollutants above a minimum temperature, the so-called light-off temperature.

[0007] Known solutions in the prior art include so-called heating catalysts, which have a metallic structure connected to a voltage source or a metallically coated ceramic structure which can be heated by utilizing the ohmic resistance.

[0008] The heatable metallic structures can, for example, consist of a honeycomb body made of metal foils. For this purpose, a plurality of smooth and / or at least partially structured metal foils are stacked on top of one another and wound around at least one pivot point to form a honeycomb body. The matrix formed from the metal foils can be electrically contacted and heated using the ohmic resistance.

[0009] For this purpose, the matrix must be arranged in an exhaust gas line and be located upstream or downstream of a catalyst designed for exhaust gas aftertreatment in the flow direction of the exhaust gas.

[0010] In order to position the matrix in the exhaust system and to support it in particular against mechanical and thermal loads, a support must be provided, which in particular occurs with the high thermal alternating loads and also with the strong and irregular mechanical loads in an exhaust system, in particular the exhaust system of a motor vehicle.

[0011] A particular disadvantage of the known solutions in the state of the art is that the structures are very complex and therefore not cost-optimal.

[0012] Description of the invention, task, solution, advantages

[0013] Therefore, it is the object of the present invention to provide a support structure for a heating matrix for spatially positioning the heating matrix in an exhaust gas path, which support structure has a simplified structure and has improved properties with regard to support against mechanical and thermal disturbances.

[0014] The problem with regard to the support structure is solved by a support structure having the features of claim 1.

[0015] An embodiment of the invention relates to a support structure for positioning a heating matrix in an exhaust gas path spatially delimited by a housing, wherein the heating matrix is ​​formed by a honeycomb body which has a plurality of flow channels through which flow can occur along a main flow direction, wherein the heating matrix is ​​supported relative to the inner surface of the housing by the support structure and the matrix is ​​fixed relative to the support structure by means of a plurality of coupling elements, wherein the support structure is designed in several parts, wherein the support structure has at least one central ring-like element and a plurality of struts which protrude in the radial direction from the ring-like element and run to the inner surface of the housing.

[0016] The support structure serves primarily to permanently position the heating matrix in the exhaust system housing. It must withstand vibrations and thermal loads and securely fix the heating matrix within the housing. Since the heating matrix is ​​energized during operation and contact with the housing must be avoided to prevent a short circuit or hazard to personnel, structural failure of the support structure must be ruled out.

[0017] A multi-part support structure design ensures that the various strength requirements of the support structure are optimally met. The connection of the support structure to the inner surface of the housing must be designed to be particularly stable and rigid to ensure secure support. However, the struts leading to the ring-like element must exhibit increased elasticity to compensate for thermally induced stresses. Furthermore, the attachment points for the coupling elements must be arranged on the support structure in such a way that sufficient tolerance compensation can be ensured during assembly.

[0018] These different requirements can best be met if the support structure is constructed from several components, which may have different material properties, in particular different thermal expansion coefficients. It is particularly advantageous if the ring-like element has at least one web that connects two points of the ring-like element. Such a web, which runs through the center of the ring-like element or at least close to the center, can provide additional stabilization of the ring-like element. Furthermore, such a web also offers the possibility of arranging coupling elements in the area of ​​the center of the support structure without causing excessive pressure loss for the exhaust gas flow.

[0019] It is also advantageous if the ring-like element is formed from a punched or laser-cut sheet metal. A preferred embodiment is characterized in that the struts are formed from a punched or laser-cut sheet metal. The aforementioned methods allow for the particularly easy production of precisely fitting components.

[0020] It is also preferable if the ring-like element and the die are joined using a durable joining process such as laser welding, soldering, or welding. Particularly due to the high thermal loads, a joining process should be selected that allows for a secure, durable connection under the given loads.

[0021] Furthermore, it is advantageous if the struts are made of profiled sheet metal, with the struts exhibiting a higher section modulus in the axial direction, which corresponds to the main flow direction of the exhaust system, compared to the radial direction. Profiled sheet metal allows for direction-dependent strength of the components, allowing them to specifically absorb higher section moduli in one spatial direction and thus be manufactured to suit the application.

[0022] Furthermore, it is advantageous if the struts are arched and evenly distributed along the circumferential direction of the housing. A plurality of struts is required to securely position the ring-like element. To ensure a homogeneous force distribution, it is therefore advantageous if the struts are evenly spaced from one another along the circumferential direction of the housing.

[0023] It is also expedient for the support structure to have a plurality of coupling elements, via which the matrix is ​​attached to the support structure. The coupling elements are arranged both on the struts and on the ring-like central element. The coupling elements serve to accommodate the heating matrix and are preferably designed to compensate for tolerances.

[0024] Advantageous further developments of the present invention are described in the subclaims and in the following description of the figures.

[0025] Short description of the drawings

[0026] The invention is explained in detail below using an exemplary embodiment with reference to the drawing. The drawing shows:

[0027] Fig. 1 is a view of a support structure comprising a ring-like element with a plurality of struts projecting in the radial direction.

[0028] Preferred embodiment of the invention

[0029] Figure 1 shows a support structure 1 formed from a centrally arranged ring-like element 3 and a plurality of struts 2. The ring-like element 3 has an S-shaped web 4, which connects two points of the ring-like element 3.

[0030] The struts 2 protrude radially outwards from the ring-like element 3 and are connected at their free end to the housing (not shown) or to another ring-like element (also not shown). In the example in Figure 1, the struts 2 are arranged omnidistantly in the circumferential direction of the ring-like element 3 and are arc-shaped. In alternative embodiments, the distances in the circumferential direction can also be different. Furthermore, the struts 2 can also be straight or have a different shape. Furthermore, additional connecting elements can be provided, which, for example, connect the individual struts 2 to one another.

[0031] These can be evenly or unevenly distributed and can connect two or more struts together.

[0032] The embodiment of Figure 1 is in particular not restrictive in nature and serves to clarify the inventive concept.

[0033] List of reference symbols

[0034] 1 . Support structure

[0035] 2. Strut 3. Ring-like element

[0036] 4. Bridge

Claims

Patent claims 1. Support structure (1) for positioning a heating matrix in an exhaust gas path spatially delimited by a housing, wherein the heating matrix is ​​formed by a honeycomb body which has a plurality of flow channels through which flow can pass along a main flow direction, wherein the heating matrix is ​​supported relative to the inner surface of the housing by the support structure (1) and the matrix is ​​fixed relative to the support structure (1) by means of a plurality of coupling elements, characterized in that the support structure (1) is designed in several parts, wherein the support structure (1) has at least one central ring-like element (3) and a plurality of struts (2) which protrude in the radial direction from the ring-like element (3) and run to the inner surface of the housing.

2. Support structure (1) according to claim 1, characterized in that the ring-like element (3) has at least one web (4) which connects two points of the ring-like element (3) to one another.

3. Support structure (1) according to one of the preceding claims, characterized in that the ring-like element (3) is formed from a punched or laser-cut sheet metal.

4. Support structure (1) according to one of the preceding claims, characterized in that the struts (2) are formed from a punched or laser-cut sheet metal.

5. Support structure (1) according to one of the preceding claims, characterized in that the ring-like element (3) and the dies (2) are connected to one another by means of a durable joining process from the group consisting of laser welding, soldering or welding. Support structure (1) according to one of the preceding claims, characterized in that the struts (2) are formed from profiled sheet metal, wherein the struts (2) have a section modulus that is increased in the axial direction, which corresponds to the main flow direction of the exhaust gas path, compared to the radial direction. Support structure (1) according to one of the preceding claims, characterized in that the struts (2) are arc-shaped and are arranged so as to be evenly distributed in the circumferential direction of the housing. Support structure (1) according to one of the preceding claims, characterized in that the support structure (1) has a plurality of coupling elements, via which the matrix is ​​fastened to the support structure (1), wherein the coupling elements are arranged both on the struts (2) and on the ring-like central element (3).

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