Device for heating exhaust gas that can flow in exhaust gas line

Abstract

The invention relates to a device for heating an exhaust gas flow of an exhaust gas source, in particular of an internal combustion engine, in which the exhaust gas flow can flow within an exhaust gas line, in which the device for heating is arranged, in which the device for heating has a heating disc (8, 11, 12, 14) consisting of a honeycomb body formed by a plurality of foils (1, 2, 9, 10, 15, 16), at least a number of the first foils (9, 10) are metallic and have a structure at least in some regions, the foils (1, 2, 9, 10, 15, 16) being stacked on one another in a stack layer and wound around at least one axis of rotation to form a honeycomb body, at least one defined conductive path being formed along the first foils (9, 10) by means of heating discs (8, 11, 12, 14) of the honeycomb body, the conductive path can be electrically connected by means of at least one electrical contact, at least one of the foils is formed by a multi-layer foil (1, 2, 15, 16), and the multi-layer foil (1, 2, 15, 16) has alternately metal layers (3, 6, 7) and ceramic layers (4, 5).

Description

Technical Field

[0001] The invention relates to a device for heating an exhaust gas source, in particular an exhaust gas flow of an internal combustion engine, wherein the exhaust gas flow can flow within an exhaust gas line and the device for heating is arranged within the exhaust gas line, wherein the device has a heating disk composed of a honeycomb body, which is formed by a plurality of foils, wherein at least a certain number of first foils are metallic and have a structure / structured construction at least in certain areas, wherein the foils are stacked on top of each other to form stacked layers and are wound around at least one rotation axis to form a honeycomb body, wherein at least one defined conductive path is formed along the first foil by the heating disk composed of the honeycomb body, which conductive path can be electrically connected by means of at least one electrical contact. Background Art

[0002] In order to heat the exhaust gas flow in the exhaust system of an internal combustion engine, electric heaters are currently used to increase the exhaust gas temperature to a preset minimum value as quickly as possible. In order to ensure that a catalytic converter provided for exhaust gas aftertreatment functions correctly, it is necessary to reach a minimum temperature associated with the system. Depending on the design, the complete chemical conversion of the exhaust gas at the catalytic converter only takes place from the so-called light-off temperature. In particular, this light-off temperature must be reached particularly quickly after a cold start in order to ensure that the exhaust gas conversion takes place in a manner that satisfies the legal provisions for exhaust gas aftertreatment.

[0003] The structural form of such electric heaters known in the prior art is a heating disk consisting of a honeycomb body. Preferably, the heating disk consists of stacked layers wound into a honeycomb body. In order to create a defined flow path, the individual layers of the heating disk are separated from one another by an air gap. The air gap is usually a few millimeters wide, so that even during operation, accidental contact between the layers is prevented.

[0004] A particular disadvantage of the prior art devices is that the creation and production of this air gap is very complex and expensive, especially in the case of large honeycomb body diameters. Furthermore, the air gap is a form of flow bypass for the exhaust gas. As a result, a certain proportion of the exhaust gas always flows through the heated structure of the heating disk, so that the heating is not optimal. Furthermore, the conversion of the exhaust gas at the heating disk itself, which acts as a catalytic converter, is also reduced.

[0005] A further disadvantage of the air gap in the heating plate is that the heating plate has a lower stability and is therefore particularly susceptible to natural vibrations, which can lead to contact between the layers or destruction of the heating plate. To prevent this, a plurality of support pins are used to support the heating plate relative to a supporting structure, such as a upstream catalytic converter or a downstream catalytic converter. These support pins significantly increase the system costs and are an additional source of faults. Furthermore, vibrations can be transmitted from the supporting structure to the heating plate via the support pins, which can damage the heating plate or cause short circuits. Summary of the invention

[0006] The object of the present invention is therefore to provide a heating disk for heating an exhaust gas flow which has no open air gap and thus eliminates the known weaknesses of the previously known heating disks. In particular, a reduction in production costs, an increase in the natural frequency of the heating disk, an improvement in the exhaust gas conversion by not providing a flow bypass, and a simplification of production should be achieved.

[0007] With regard to a heating plate, this object is achieved by a heating plate having the features of claim 1 .

[0008] One embodiment of the present invention relates to a device for heating an exhaust gas source, in particular an exhaust gas flow of an internal combustion engine, wherein the exhaust gas flow can flow within an exhaust duct and the device for heating is arranged within the exhaust duct, wherein the device has a heating disk composed of a honeycomb body, which is formed by a plurality of foils, wherein at least a certain number of first foils are metallic and have a structure at least in parts, wherein the foils are stacked on top of each other to form stacked layers and are wound around at least one rotation axis to form a honeycomb body, wherein at least one defined conductive path is formed along the first foil by the heating disk composed of the honeycomb body, which conductive path can be electrically connected by means of at least one electrical contact, wherein at least one of the foils is composed of a multilayer foil, wherein the multilayer foil alternately has metal layers and ceramic layers.

[0009] Preferably, the foil of the honeycomb body can be completely smooth, partially structured or completely structured. In particular, the structured sections can have corrugations with different amplitudes and wave frequencies. Thus, corrugated foils with large wave heights (so-called macrostructuring) as well as corrugated foils with relatively small wave heights (so-called microstructuring) can be used.

[0010] The stacking of smooth or microstructured foils and macrostructured foils on one another produces a honeycomb pattern, wherein flow channels are formed between the respective adjacent foils. By winding the stacked layers, a honeycomb body is produced, which has two essentially smooth end sides, wherein the flow channels can extend from one end side to the other end side and flow can flow through in the main flow direction.

[0011] Preferably, the individual foils of the honeycomb body are durably connected to one another, for example by welding, after winding and, if necessary, after being inserted into the jacket. For this purpose, a welding material is applied by a suitable method, which is melted in a welding furnace and thus establishes a durable connection.

[0012] The multilayer foil is characterized in that the multilayer foil is composed of a plurality of layers. In the case according to the invention, the multilayer foil preferably has five layers. A metal layer, such as a metal foil or a fabric, is arranged in the center. Ceramic layers are applied to the metal layer on both sides. The ceramic layers are used to electrically insulate the adjacently arranged metal layers.

[0013] The ceramic layer is followed on both sides by a metal layer. The metal layer then forms the outer, visible outer surface of the multilayer foil. This metallic outer layer is particularly advantageous because it allows a connection to an adjacent foil of a honeycomb body. The multilayer foil can be connected to a pure metal foil in a simple manner using the same working steps as the other foils.

[0014] The central metal layer gives the multilayer foil the necessary stability, wherein the multilayer foil is preferably also designed to be flexible so that very small bending radii, preferably about 1 mm, can be achieved. The ceramic layer ensures electrical insulation, effectively preventing unintentional electrical conduction on the multilayer foil.

[0015] The metallic outer layers are contact layers via which the multilayer foil can be connected to the remaining foils.

[0016] In the simplest case, the multilayer foil can consist of only three layers, wherein a central ceramic layer is provided, which adjoins the metal layer. Alternative designs can also have, for example, seven or nine layers, as long as the basic concept of at least one ceramic layer in the center and one metal layer as outer layer is adhered to.

[0017] A stack of layers consisting of metal foils and multilayer foils can be wound up in a simple manner to form a honeycomb body. The multilayer foil ensures that the honeycomb body has layers that are electrically insulated from one another and that form a current path that extends from the inlet point to the outlet point. The air gap that is otherwise common in heating plates is eliminated and is no longer necessary due to the use of the multilayer foil.

[0018] It is particularly advantageous if the multilayer foil has five individual layers, wherein the multilayer foil has a metal core which is covered on both sides by a ceramic layer, wherein the ceramic layer adjoins a further metal layer.

[0019] Five layers are advantageous because the central metal layer is provided for establishing the stability of the multilayer foil. The two ceramic layers on both sides are provided for electrical insulation, while the two metal layers on both sides are provided for connecting the multilayer foil to the remaining foils of the stack.

[0020] It is also advantageous if the multilayer foil is designed to be smooth and is arranged between two adjacent, at least partially structured first foils. The multilayer foil can be used as a smooth foil and in particular arranged between two at least partially structured foils. It is also conceivable to arrange a foil with a macrostructure on one side and a foil with a microstructure on the other side.

[0021] A preferred embodiment is characterized in that the multilayer foil is designed to be at least partially structured, in particular corrugated, and is arranged between two smooth first foils. The multilayer foil has a technical feature that also allows the multilayer foil to be corrugated and molded with microstructures or macrostructures. Thus, the multilayer foil can be arranged in the stack instead of any other foil used.

[0022] It is also preferred that the layer stack has two multilayer foils which are spaced apart from one another by at least one first metal foil.

[0023] A plurality of multilayer foils is particularly advantageous because the insulating effect can thereby be doubled. For example, two multilayer foils can be arranged in a stacked layer, for example in a manner spaced apart from each other by the structured foil. It is also conceivable to create a plurality of mutually independent conductive paths by using a plurality of multilayer foils.

[0024] It is also advantageous that the multilayer foil is durably connected to the directly adjacent first foil in the honeycomb body on its outer metal layer. In particular, this durably connected is established by a welding method, because the connection of the metal foils to each other and the connection of the multilayer foil to the metal foil can be established in one working process.

[0025] It is also advantageous if the device additionally comprises an auxiliary catalytic converter formed by a honeycomb body, the heating plate being supported relative to the auxiliary catalytic converter, the auxiliary catalytic converter being formed by stacking and winding a plurality of foils on one another, the auxiliary catalytic converter comprising at least one multilayer foil which projects in the main flow direction beyond one of the end sides of the auxiliary catalytic converter.

[0026] In order to advantageously position the heating disk in the exhaust gas line and in particular to prevent electrical contact with other elements, the heating disk can preferably be supported in an electrically insulated manner relative to a supporting structure such as, for example, another honeycomb body.

[0027] According to the invention, the honeycomb body used as an auxiliary catalytic converter can have at least one multilayer foil for this purpose, which, however, has a longer extension in the main flow direction of the honeycomb body than the remaining metal foil and thus protrudes beyond the end face delimiting the flow channel at least on one side.

[0028] The protruding multilayer foil is then preferably part of a stack of layers forming the heating disk. If the auxiliary catalytic converter and the heating disk have an identical or at least very similar structure, in particular with regard to the number of layers and the winding method, the two honeycomb bodies can be wound in a common working process and subsequently welded.

[0029] The multilayer foil thus assumes the function of supporting the heating disk relative to the auxiliary catalytic converter and simultaneously also assumes the electrical insulation of the conducting paths of the heating disk itself and of the heating disk from the auxiliary catalytic converter.

[0030] It is also suitable that the multilayer foil extending outside the end face of the auxiliary catalytic converter is also a part of the stacked layers of the honeycomb body forming the heating plate. In this way, the heating plate and the auxiliary catalytic converter are fixedly connected to each other and electrically insulated from each other in a suitable manner.

[0031] Furthermore, it is advantageous if the heating disk is fixed relative to the auxiliary catalytic converter and is spaced apart therefrom by means of a multilayer foil projecting outside the auxiliary catalytic converter.

[0032] Furthermore, it is expedient if the multilayer foil of the auxiliary catalytic converter has five layers, wherein the middle layer is a metal layer which has a ceramic layer on both sides, wherein a metal layer follows the ceramic layer in each case.

[0033] Advantageous developments of the invention are described in the dependent claims and in the following description of the figures. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention will be described in detail below with reference to the accompanying drawings according to the embodiments.

[0035] Figure 1 shows a cross-section through a multilayer foil according to the invention, wherein the multilayer foil is shown once as a smooth foil and once as a foil with structure,

[0036] Figure 2 A view showing a stacked layer with two multilayer foils,

[0037] Figure 3 A view showing stacked layers of a multilayer foil having a corrugated shape,

[0038] Figure 4 A view showing stacked layers with a smooth multilayer foil, and

[0039] Figure 5 A section through an auxiliary catalytic converter with a multilayer foil protruding in the flow direction is shown, wherein a heating disk is also shown spaced apart from the auxiliary catalytic converter. DETAILED DESCRIPTION

[0040] Figure 1 In the upper region, a multilayer foil 1 is shown which consists of five layers. Figure 1 In the upper region of the multilayer foil 1 is designed to be smooth. Figure 1 The lower region of FIG. 2 shows a multilayer foil 2 which is structured, in particular corrugated.

[0041] The two multilayer foils 1 , 2 have five layers, of which the central layer 3 is metallic and the two adjacent layers 4 , 5 are ceramic. The respective outer layers 6 , 7 are again made of metal.

[0042] Figure 2 The cross section through a heating plate 8 is shown, wherein the heating plate 8 is composed of a plurality of metal foils 9, 10. Two multilayer foils 1 are arranged within the heating plate, wherein the outer layers 6, 7 of the multilayer foils 1 are in contact with the respectively adjacent metal foil 9, 10 and are durably connected to one another.

[0043] The two multilayer foils 1 are separated from each other by a corrugated metal foil 9. Figure 2 The heating plate shown in FIG. 1 is composed of a foil 9 with a coarse structure (with a macrostructure) and a foil 10 with a fine structure (with a microstructure).

[0044] Figure 3 A section through an alternative heating plate 11 is shown, wherein the heating plate 11 is likewise composed of a macrostructured foil 9 and a microstructured foil 10. The heating plate 11 has a multilayer foil 2 which is arranged between two microstructured foils 10.

[0045] Figure 4 A further alternative heating plate 12 is shown, wherein the heating plate 12 is likewise composed of a macrostructured foil 9 and a microstructured foil 10. The heating plate 12 has a multilayer foil 1 which is arranged between two microstructured foils 10.

[0046] Figure 5 A section through an auxiliary catalytic converter 13 consisting of a wound stack of layers is shown. A heating disk 14 is depicted above the auxiliary catalytic converter 13, which is also composed of a wound stack of layers.

[0047] exist Figure 5 In the left part of the auxiliary catalytic converter 13, the auxiliary catalytic converter 13 has a corrugated multilayer foil 15, which protrudes out of the upper end side of the auxiliary catalytic converter 13. In the right part, the auxiliary catalytic converter 13 has a smooth multilayer foil 16, which also protrudes out of the upper end side. Figure 5 The auxiliary catalytic converter shown in is exemplary, and different multilayer foils 15, 16 should illustrate that not only smooth multilayer foils but also corrugated multilayer foils are feasible. In a practical embodiment, the auxiliary catalytic converter 13 and the multilayer foil extending outside the end side are designed as unified on the entire cross section. Figure 5 Two partial views are used to illustrate different design options.

[0048] Different features of the individual embodiments may also be combined with one another.

[0049] Figures 1 to 5 The exemplary embodiments are particularly not to be construed as limiting and serve to illustrate the idea of ​​the invention.

[0050] List of reference numerals:

[0051] 1 Multi-layer foil smooth

[0052] 2 Multi-layer foil corrugated

[0053] 3Central metal layer

[0054] 4 Ceramic Layers

[0055] 5 Ceramic Layer

[0056] 6 Metal Layers

[0057] 7 Metal Layer

[0058] 8 Heating plate

[0059] 9 Foils with macrostructure

[0060] 10 Microstructured foil

[0061] 11 Heating plate

[0062] 12 Heating plate

[0063] 13 Auxiliary catalytic converter

[0064] 14 Heating plate

[0065] 15 Corrugated multilayer foil

[0066] 16 Smooth multi-layer foil

Claims

1. A device for heating an exhaust gas source, in particular an exhaust gas flow of an internal combustion engine, wherein: An exhaust gas flow can flow in an exhaust gas line, a device for heating is arranged in the exhaust gas line, wherein the device has a heating plate (8, 11, 12, 14) formed by a honeycomb body, the honeycomb body being formed by a plurality of foils (1, 2, 9, 10, 15, 16), wherein at least a certain number of first foils (9, 10) are metallic and at least partially structured, wherein the foils (1, 2, 9, 10, 15, 16) are stacked on top of one another to form stacked layers and wound around at least one rotation axis to form a honeycomb body, wherein the heating plate (8, 11, 12, 14) formed by the honeycomb body forms at least one defined conductive path along the first foil (9, 10), which conductive path can be electrically connected by means of at least one electrical contact, It is characterized in that At least one of the foils is formed by a multilayer foil (1, 2, 15, 16), wherein the multilayer foil (1, 2, 15, 16) alternately comprises metal layers (3, 6, 7) and ceramic layers (4, 5).

2. The device according to claim 1, characterized in that The multilayer foil (1, 2, 15, 16) has five individual layers (3, 4, 5, 6, 7), wherein the multilayer foil (1, 2, 15, 16) has a metal core (3) which is covered on both sides by a ceramic layer (4, 5), wherein the ceramic layer (4, 5) adjoins a further metal layer (6, 7).

3. The device according to any one of the preceding claims, characterized in that The multilayer foil (1, 16) is smooth and is arranged between two adjacent first foils (9, 10) which are at least partially structured.

4. The device according to any one of the preceding claims, characterized in that The multilayer foil (2, 15) is designed to be at least partially structured, in particular corrugated, and is arranged between two smooth first foils.

5. The device according to any one of the preceding claims, characterized in that The stack has two multilayer foils (1) which are spaced apart from one another by at least one first metal foil (9).

6. The device according to any one of the preceding claims, characterized in that The multilayer foil (1, 2, 15, 16) is durably connected at its outer metal layer (7, 8) to the directly adjacent first foil (9, 10) in the honeycomb body.

7. Apparatus according to any one of the preceding claims, wherein: The device additionally comprises an auxiliary catalytic converter (13) formed by a honeycomb body, the heating plate (14) being supported relative to the auxiliary catalytic converter, characterized in that the auxiliary catalytic converter (13) is formed by stacking and winding a plurality of foils on each other, wherein the auxiliary catalytic converter (13) comprises at least one multilayer foil (15, 16) which projects beyond one end side of the auxiliary catalytic converter (13) in the main flow direction.

8. The device according to claim 7, characterized in that The multilayer foil (15, 16) which projects beyond the end face of the auxiliary catalytic converter (13) is also part of the stack of layers which forms the honeycomb body of the heating disk (14).

9. The device according to any one of the preceding claims, characterized in that The heating plate (14) is fixed relative to the auxiliary catalytic converter (13) and spaced apart therefrom by means of a multilayer foil (15, 16) extending out of the auxiliary catalytic converter (13).

10. The device according to any one of the preceding claims, characterized in that The multilayer foil (15, 16) of the auxiliary catalytic converter has five layers, wherein the middle layer is a metal layer which has a ceramic layer on both sides, wherein each ceramic layer is followed by a metal layer.

Images