Support structure for heating plate

Abstract

The invention relates to a device for the exhaust gas aftertreatment of an internal combustion engine, comprising: a flow path which is spatially delimited by a housing and through which exhaust gas can flow; the invention relates to a metal heating substrate (10, 16) having a plurality of flow channels, which are formed between a plurality of metal foils stacked on top of one another and wound around at least one axis of rotation, and through which exhaust gas can flow in a main flow direction from a gas inlet side to a gas outlet side, the heating substrate (10, 16) can be connected to a power supply and can be heated using an ohmic resistor; a support structure (1, 7, 17) which is integrally bonded to the housing and which is connected to the heating substrate (10, 16) by means of a plurality of coupling elements (18), the support structure (1, 7, 17) having an annular region (2) which rests on the inner surface of the housing and which has a plurality of arms (3) which protrude from the annular region (2) towards the center of the housing, the plurality of arms (3) terminate in a closed circular region (4, 8) in the center of the housing.

Description

Field of the Invention

[0001] The present invention relates to a device for exhaust gas aftertreatment of an internal combustion engine, the device having: a flow path spatially delimited by a housing, through which exhaust gas can flow; a metallic heating substrate having a plurality of flow channels which are formed between a plurality of metal foils stacked on one another and wound around at least one axis of rotation, wherein the exhaust gas can flow through the plurality of flow channels in a main flow-through direction from a gas inlet side towards a gas outlet side, wherein the heating substrate can be connected to a power supply and can be heated using ohmic resistance; a support structure which is connected to the housing in a materially locking manner and is connected to the heating substrate by means of a plurality of connecting elements. Background Art

[0002] In order to heat the exhaust gas in the exhaust section downstream of the internal combustion engine or the exhaust gas flowing in the exhaust section, electrical heating elements are currently usually used. The aim pursued here is to reach a temperature threshold more quickly, from which the harmful substances carried in the exhaust gas can be effectively converted. This is necessary because the catalytically active surface of the catalytic converter installed in the exhaust section for exhaust gas aftertreatment can only achieve sufficient conversion of the corresponding harmful substances from a minimum temperature, the so-called light-off temperature.

[0003] Solutions known from the prior art include so-called heated catalytic converters, which have a metallic structure or a ceramic structure coated with metal connected to a power supply and which can be heated using ohmic resistance.

[0004] The heatable metallic structure can for example consist of a honeycomb body made of metal foil. For this purpose, a plurality of smooth and / or at least partially structured metal foils are stacked on one another and wound around at least one pivot point to form a honeycomb body. The substrate formed by the metal foil can be electrically contacted and can be heated using ohmic resistance.

[0005] For this purpose, the substrate must be arranged in the exhaust section and be placed upstream or downstream of a catalytic converter designed for exhaust gas aftertreatment in the flow direction of the exhaust gas.

[0006] In order to position the substrate in the exhaust section and support the substrate, in particular to overcome mechanical and thermal loads, such a support must be provided which, in particular, can withstand the high alternating thermal loads in the exhaust section, in particular in the vehicle exhaust section, and in addition strong and irregular mechanical loads.

[0007] Particularly disadvantageous in the solutions known from the prior art is that the structure is very complex and thus the costs are not optimal. Summary of the Invention

[0008] Accordingly, the object of the present invention is to provide a device capable of securely and durably positioning a heating matrix in a flow path guiding the exhaust gas.

[0009] In terms of the device, this object is achieved by a device having the features described in claim 1.

[0010] An embodiment of the present invention relates to a device for the exhaust gas aftertreatment of an internal combustion engine, the device having: a flow path spatially delimited by a housing, through which the exhaust gas can flow; a metallic heating matrix having a plurality of flow channels which are configured between a plurality of metal foils stacked on one another and wound around at least one axis of rotation, wherein the exhaust gas can flow through the plurality of flow channels in a main flow-through direction from a gas inlet side towards a gas outlet side, wherein the heating matrix can be connected to a power supply and can be heated using ohmic resistance; a support structure which is connected to the housing in a material-locking manner and is connected to the heating matrix by means of a plurality of coupling elements, wherein the support structure has an annular region which abuts against the inner surface of the housing and has a plurality of arms extending from the annular region towards the center of the housing, and wherein the arms terminate in a closed circular region in the center of the housing.

[0011] Preferably, the annular region extends in the circumferential direction of the housing as a completely closed ring. The width of the ring in the radial direction of the housing is preferably 2 mm to 10 mm, particularly preferably 4 mm to 6 mm. The thickness of the ring in the axial direction of the housing is preferably 1 mm to 6 mm, particularly preferably 2 mm to 4 mm.

[0012] The configuration of the support structure is selected such that the vibrations from the plane of the support structure or the heating matrix are minimized as much as possible. In particular, movement beyond this plane along the main flow-through direction should be avoided. Furthermore, the natural frequencies of the support structure and the heating matrix should be as high as possible. In the case of a PKW (passenger car), the natural frequency is preferably higher than 800 Hz, and in the case of an LKW (commercial vehicle), the natural frequency is higher than 400 Hz, in order to thereby keep the overlap with the vibrations occurring during operation as small as possible.

[0013] Preferably, the support structure has 6 to 12 arms which extend from the annular region at the housing towards the center. The arms have an arcuate or involute shape and are preferably bent in a direction corresponding to the winding direction of the heating matrix. A defined torsional movement of the support structure should be achieved by the arcuate design of the arms.

[0014] Particularly advantageously, the arms extend arcuately in the plane of the support structure, where the arms are bent in the same direction in the circumferential direction. A spiral design is produced by the bending of the arms. Preferably, the bending of the arms is adapted to the spiral shape of the heating substrate, so that the arms optimally follow the course of the individual winding layers of the heating substrate.

[0015] It is also advantageous that the enclosed circular area arranged centrally has cross struts that follow the course of the metal foil forming the heating substrate. Since the heating substrate is preferably wound around two winding mandrels, the heating substrate forms a so-called S-shaped curve, which describes the S-shaped winding of the stacked layers around the two winding mandrels. In order to be able to optimally stabilize the center of the heating substrate in particular, the cross struts follow the stacked layers in this central area, so that this area can be directly connected by means of connecting elements.

[0016] A preferred embodiment is characterized in that the arcuate direction of the arms is the same as the winding direction of the metal foil of the heating substrate. This helps to absorb torsional forces that may arise due to heating. Due to the self-heating or external heating of the spiral heating substrate, the spiral heating substrate thermally expands and at the same time undergoes a torsional movement. If the support structure cannot sufficiently follow this movement, after a certain torsional movement, the connecting elements may break or the heating substrate and / or the support structure may be damaged.

[0017] It is also preferred that the maximum distance between the connecting elements does not exceed 80 mm. Thereby, the distribution of the connecting elements on the cross section of the heating substrate is asymmetrical, where in the outer region close to the housing, fewer connecting elements are arranged, and in the center, a relatively larger number of connecting elements are arranged in terms of area. This is advantageous because due to the winding, the heating substrate has a stronger bend in the center. Preferably, this bend must be supported between the winding layers, i.e., supported as closely as possible, so that the heating substrate is particularly stably supported here.

[0018] Furthermore, it is advantageous that the support structure has receiving points to which the connecting elements are connected to the support structure. For example, the receiving point can be a hole in the support structure into which the connecting element is inserted and connected to the support structure. Preferably, the hole has a diameter of 4 mm to 10 mm. Alternatively, a slot can be provided, which can achieve compensation for the tolerances of the heating substrate, the connecting elements or the support structure itself. The slot has an inner opening width significantly larger than the diameter of the free end of the connecting element. Preferably, the slot has a width of 2 mm to 4 mm and a length of 4 mm to 10 mm. Alternatively, the receiving point can be formed by a recess in the support structure, and the recess is used as a solder reservoir, for example, and thus enables simple connection to the connecting element by means of soldering. The recess can also have an inner opening width larger than the connecting element to achieve tolerance compensation.

[0019] Furthermore, it is advantageous that support structures are arranged upstream and downstream of the heating substrate in the flow direction. Here, the support structures can be implemented as identical or different. Preferably, only a unilateral support structure is arranged on the gas inlet side of the heating substrate. Thereby, the support structure itself does not serve as a heat dissipation structure, and the flow distribution in the flow path is not affected by the structure arranged downstream of the heating substrate.

[0020] It is also suitable that the support structure is configured as raised / convex. In particular, a convex support structure shape is advantageous. Here, the support structure protrudes convexly from its actual plane through its center. This helps to shift the natural frequency of the support structure further in the direction of a risk-free frequency range, and thus the natural frequency is shifted out of the frequency range that usually occurs during operation.

[0021] Furthermore, it is advantageous that support structures are arranged upstream and downstream of the heating substrate in the flow direction, wherein the support structures bulge in the same or opposite directions to each other.

[0022] It is also suitable that the heating substrate is formed by stacked layers, the stacked layers are formed by a plurality of metal foils stacked on top of each other, wherein the stacked layers are helically wound by means of two rotating mandrels, and the windings of the stacked layers are spaced apart from each other by air gaps. In order to generate a targeted current path along the heating substrate and achieve as uniform heating of the heating substrate as possible, this spacing of the winding layers from each other is necessary.

[0023] Advantageous refinements of the invention are described in the dependent claims and in the following description of the drawings. Description of the Drawings

[0024] The present invention will be described in detail below with reference to the drawings according to embodiments. The figures show:

[0025] Figure 1 A perspective view of a support structure having a plurality of arms that arc from an outer annular region towards an inner annular region,

[0026] Figure 2 A perspective view of an alternatively configured support structure,

[0027] Figure 3 A schematic view of a support structure having arcuate arms and a schematic view of an s-shaped wound heating substrate, and

[0028] Figure 4 A view of a heating substrate received between two support structures, wherein different bulging schemes of the support structures are shown. Detailed Description of the Embodiments

[0029] Figure 1The support structure 1 is shown, which has an annular region 2 designed to be connected to the inner surface of the housing that spatially defines the flow path. A plurality of arms 3 project from the annular region 2, and these arms point radially inward in an arcuate manner. The arms 3 terminate centrally in a circular region 4 of the support structure 1. The arms 3 are all blade-shaped and curved in the same direction, so that the arms 3 have an impeller-like arrangement structure.

[0030] The circular region 4 has cross braces 5 that connect two points, preferably opposite points, of the circular region 4 to each other through the center of the support structure 1. In the example of the drawing, the cross braces 5 are curved in an s-shape and thus particularly follow the so-called s-shaped curve of a heating plate (not shown), which is generated when a stacked layer of metal foil is wound around two winding mandrels. This has the advantage that the center of the heating plate (not shown), which forms the main part of the total mass of the heating plate, can also be supported multiple times relative to the support structure 1. In an alternative design, the circular region and in particular the cross braces can also follow another shape preferably adapted to the layer orientation of the heating plate.

[0031] The support structure 1 has a plurality of recesses 6 that serve as connection points for connection elements, through which the heating plate can be connected to the support structure 1. In Figure 1 the embodiment, the recesses 6 are configured as elongated holes. The recesses 6 can also be used as solder reservoirs and for compensating tolerances. As solder reservoirs, the recesses 6 are pre-filled with solder, so that inserting the heating plate together with the connection elements causes the free ends of the connection elements to dip into the recesses 6, and thus the free ends also dip into the solder. During the subsequent soldering process, the connection elements are durably connected to the support structure 1.

[0032] Due to the elongated hole configuration of the recesses 6, the recesses can compensate for the positional tolerances of the connection elements at least along the longer extension of the recesses 6, which may be caused by the manufacturing tolerances of the heating plate, the connection elements, and the support structure 1 or by the tolerances caused by assembly.

[0033] The support structure 1 can be made of castings, plates, or other metallic materials. Figure 1 The embodiment of shows a support structure 1 with a circular cross-section that is adapted to a housing that also has a circular cross-section.

[0034] Figure 2 An embodiment of a support structure 7 is shown, in which the support structure 7 has a different cross-section. The remaining structure is the same as that of Figure 1 The support structure 7 has a rectangular cross-section with rounded corners. The central circular region 8 has an elliptical cross-section and straight cross braces 9.

[0035] Figure 3 A schematic view of a helically wound heating disk 10 is shown in the left region. The heating disk 10 has an S-shaped bent center 11. At the upper and lower ends of the stacked layer 12 forming the heating disk 10, electrical connection terminals 13 are provided through which the heating disk 10 can be energized.

[0036] Arrow 14 shows the direction of movement of the wound heating disk 10 when loaded with sufficient heat Q. Due to its winding direction, the heating disk 10 performs a counterclockwise torsional movement and actually winds more strongly.

[0037] In Figure 3 a schematic view of the support structure 1 is shown in the right region, and the support structure is substantially corresponding to Figure 1 the support structure 1. Under the action of heat Q, the support structure 1 also performs a counterclockwise torsional movement in the direction of arrow 15 due to the arc design of the arm 3.

[0038] Therefore, the heating disk 10 and the support structure 1 are designed such that the heating disk and the support structure twist in the same direction under the action of heat, thereby preventing excessive relative movement between the support structure 1 and the heating disk 10 and thus avoiding damage to the coupling element, the heating disk 10 or the support structure 1.

[0039] Figure 4 A cross-sectional view of the heating disk 16 is shown in the left part. The heating disk is arranged between two support structures 17 and is connected to the support structures 17 through a coupling element 18. In Figure 4 the right part, three different configuration schemes of the two support structures 17 are shown.

[0040] In the upper figure, the two support structures 17 bulge convexly in the same direction and arch out from their base planes. In the middle figure on the right, two support structures 17 that bulge convexly are shown, but their directions are opposite. In this case, both support structures 17 protrude away from the heating disk 16. The lower figure shows a configuration scheme with one flat support structure 17 and one convexly bulging support structure 17.

[0041] Figures 1 to 4 The embodiments of

[0042] are not particularly restrictive features and are used to illustrate the idea of the present invention.

[0043] 1 Support structure

[0044] 2 Annular region

[0045] 3 Arm

[0046] 4 Circular region

[0047] 5 Transverse strut

[0048] 6 Concave part

[0049] 7 Support structure

[0050] 8 Circular area

[0051] 9 Transverse strut

[0052] 10 Heating plate

[0053] 11 S-shaped bent center

[0054] 12 Stacked layer

[0055] 13 Electrical connection end

[0056] 14 Arrow

[0057] 15 Arrow

[0058] 16 Heating plate

[0059] 17 Support structure

[0060] 18 Connecting element

Claims

1. An apparatus for the exhaust gas aftertreatment of an internal combustion engine, the apparatus having: a flow path spatially delimited by a housing, through which exhaust gas can flow; Heating matrix (10, 16) for a metal, the heating matrix for a metal having a plurality of flow channels which are configured between a plurality of metal foils stacked on one another and wound around at least one axis of rotation, wherein, the exhaust gas can flow through the plurality of flow channels in a main flow-through direction from a gas inlet side towards a gas outlet side, wherein a heating substrate (10, 16) can be connected to a power supply and can be heated using ohmic resistance; a support structure (1, 7, 17), which is connected to the housing in a material-locking manner and is connected to the heating substrate (10, 16) by means of a plurality of connecting elements (18); characterized in that the support structure (1, 7, 17) has an annular region (2), which abuts against the inner surface of the housing and has a plurality of arms (3) extending from the annular region (2) towards the center of the housing, wherein the plurality of arms (3) terminate in a closed circular region (4, 8) in the center of the housing.

2. The device according to claim 1, characterized in that The arms (3) extend arcuately in the plane of the support structure (1, 7, 17), wherein the arms (3) are bent in the same direction in the circumferential direction.

3. The device according to any one of the preceding claims, characterized in that, The centrally arranged closed circular region (4, 8) has cross braces (5, 9), which follow the course of the metal foils forming the heating substrate (10, 16).

4. The device according to any one of the preceding claims, characterized in that The arcuate direction of the arms (3) is the same as the winding direction of the metal foils of the heating substrate (10, 16).

5. The device according to any one of the preceding claims, characterized in that, The maximum distance between the connecting elements (18) from each other does not exceed 80 mm.

6. The device according to any one of the preceding claims, characterized in that, The support structure (1, 7, 17) has receiving points (6) on which the connecting elements (18) are connected to the support structure (1, 7, 17).

7. The device according to any one of the preceding claims, characterized in that, Support structures (17) are arranged upstream and downstream of the heating substrate (16) in the flow direction.

8. The device according to any one of the preceding claims, characterized in that, The support structure (17) is configured to be raised.

9. The device according to any one of the preceding claims, characterized in that, Support structures (17) are arranged upstream and downstream of the heating substrate (16) in the flow direction, wherein the support structures (17) are raised in the same direction or in opposite directions to each other.

10. The device according to any one of the preceding claims, characterized in that, The heating substrate (10, 16) is formed by a stacked layer (12), which is formed by a plurality of metal foils stacked on top of each other, wherein the stacked layer (12) is helically wound with the aid of two rotating mandrels, wherein the windings of the stacked layer (12) are spaced apart from each other by air gaps.

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