Apparatus for exhaust aftertreatment and manufacturing method

Abstract

The invention relates to a device for cleaning the exhaust gases of an internal combustion engine, comprising a heating disc (7) made of a metal honeycomb body, said heating disc (7) being formed from a plurality of metal foils which are stacked on top of one another and are wound around at least one axis of rotation, said heating disc (7) having air gaps (8) between the winding layers, the honeycomb body has a plurality of flow channels through which exhaust gas can flow, the heating disc (7) has a plurality of supporting elements (2), and the supporting elements (2) of the heating disc (7) are inserted into the air gaps (8) formed between the winding layers.

Description

Field of the Invention

[0001] The present invention relates to a device for purifying the exhaust gas of an internal combustion engine, which device has a heating disk formed by a metallic honeycomb body, wherein the heating disk is formed by a plurality of metal foils stacked on one another and wound around at least one axis of rotation, wherein the heating disk has air gaps between the winding layers, which air gaps space the winding layers apart from one another and define a flow path along the heating disk, wherein the honeycomb body has a plurality of flow channels through which the exhaust gas can flow, and wherein the heating disk has a plurality of support elements. The invention also relates to a method for manufacturing the device. Background Art

[0002] In the prior art, support pins are known for connecting an electrically heated disk designed as a metallic honeycomb body to other honeycomb bodies of a so-called auxiliary catalytic converter, which support pins are inserted into the cells of the respective honeycomb bodies and are durably connected thereto by welding. Herein, the support pins on the one hand assume the task of spatially fixing the heating disk relative to the auxiliary catalytic converter, and on the other hand assume the task of electrolytic decoupling between the two honeycomb bodies.

[0003] The durable connection between the honeycomb body and the support pins is preferably effected between its metal sleeve or its metal core and the corrugated metal foil of the respective honeycomb body.

[0004] Depending on the design of the heating disk, more or fewer support pins are provided, wherein the support pins are also arranged in multiple rows if necessary. Herein, in particular in view of the thermal and mechanical loads, the support pins are arranged such that as high a durability as possible can be expected during operation.

[0005] The disadvantages of the devices in the prior art lie particularly in that a large number of support pins are required, which results in high manufacturing costs. In addition, the heating disks made of metallic honeycomb bodies known to date have the disadvantage that, since the individual laminated components are electrically insulated from one another, air gaps must be formed between the individual layers, which makes the honeycomb body unstable and particularly prone to harmful vibration phenomena due to the low natural frequency. In addition, the air gaps represent a bypass through which the exhaust gas may inadvertently flow past the heating disk.

[0006] In addition, in order to achieve a good fit between the support pins and the corrugated layers of the honeycomb body, the corrugated layers must be specifically adjusted in view of their cell density and profile, otherwise defects and connection failures may occur during the welding process, which will have a negative impact on the structural integrity.

[0007] In addition, the support pins cause the respective cells into which they are inserted to become blocked, whereby these cells or flow channels can no longer be used for exhaust gas aftertreatment. Summary of the Invention

[0008] Accordingly, the object of the present invention is to provide a device having a heatable heating disk, which device has an optimized structure and can be connected, if necessary, to an upstream or downstream auxiliary catalytic converter by means of suitable support elements.

[0009] The object in respect of the device is achieved by a device having the features of claim 1.

[0010] An embodiment of the invention relates to a device for purifying the exhaust gas of an internal combustion engine, which device has a heating disk formed by a metallic honeycomb body, wherein the heating disk is formed by a plurality of metal foils stacked on top of one another and wound around at least one axis of rotation, wherein the heating disk has air gaps between the winding layers, which air gaps space the winding layers apart from one another and define a flow path along the heating disk, wherein the honeycomb body has a plurality of flow channels through which the exhaust gas can flow, wherein the heating disk has a plurality of support elements, and wherein the support elements of the heating disk are inserted into the air gaps formed between the winding layers.

[0011] By inserting the support elements into the air gaps formed between the respective winding layers, a connection is established between the respective winding layers and the respective winding layers are enabled to support one another. By this mutual support, the stability of the heating disk thus produced is significantly increased, thereby improving the durability especially in view of the mechanical loading of the heating disk, which can be caused by the vibration of the heating disk itself and / or the vibration of other components in the exhaust system. In particular, by inserting the support elements and by connecting the winding layers to one another, the number of different bending natural frequencies of the heating disk is reduced.

[0012] By increasing the stability of the heating disk, a large number of commonly used support elements can also be dispensed with, since the number of connection points to the auxiliary catalytic converter supporting the heating disk can be significantly reduced.

[0013] Preferably, the support elements are only inserted into the air gaps, which achieves a plurality of advantages. On the one hand, the flow channels formed in the heating disk are not blocked by the support elements.

[0014] Thus, the exhaust gas can flow through all the flow channels, thereby enabling the actual use of the heating disk, namely heating the exhaust gas, to be improved. In addition, there is no longer a need to adapt the support elements to the geometry of the formed flow channels. Thereby, the variety of components can be reduced, which enables the production to be simplified. In addition, heating disks with a small number of cells, for example 50 or 75 cells per square inch (cpsi) as in truck applications, can be positioned using standard support elements, which are usually too narrow for the cell size of the heating disk.

[0015] Furthermore, the support element at least partially blocks the air gap, and due to the exhaust gas flowing through this air gap, an unwanted bypass effect is inevitably generated. In addition, the heating of the heating plate can be made more uniform by positioning the support element according to the present invention.

[0016] A preferred embodiment is characterized in that the support element inserted into the air gap contacts the two respective winding layers that define the air gap in the radial direction and is durably connected to the two winding layers. On the one hand, this results in high stability of the heating plate, and on the other hand, the formation of the flow path can be influenced in a targeted manner, and this flow path generates the current between the two electrical connectors of the heating plate. By selecting a support element that does not have electrical insulation, the two winding layers can be brought into conductive contact with each other, thereby widening the flow path. In addition, a stronger current can be applied to a region of the heating plate in a targeted manner, for example, to ensure an improved heat distribution on the heating plate. A so-called discrete current bridge that influences the current flow is formed by the conductive support element.

[0017] By selecting a support element with an electrical insulation effect, for example, by means of a suitable coating or an electrical insulation layer, the winding layers can be electrically insulated from each other in a targeted manner.

[0018] It is also preferred that at least a first number of support elements are formed by support pins, wherein the support pins have a pin-shaped core, the end sides of which are wrapped with an electrically insulating material, and wherein the electrically insulating material has two regions with a metal coating on its outer periphery, and the two regions are not in conductive contact with each other, and the support pins protrude beyond the heating plate in the axial extension direction of the heating plate.

[0019] The first support element is formed similarly to a conventional support pin. It is characterized in that the first support element is inserted into the heating plate at one end region, more precisely into the air gap of the heating plate, and is connected to a support structure, such as an upstream or downstream auxiliary catalytic converter, at its opposite end region. Depending on the application, the support pin can be designed with electrical insulation or conductively. The insulated support pin usually has a metal core, which is surrounded by an electrically insulating layer in the end region, and the insulating layer - usually ceramic - has two non-connected regions provided with a metal coating, through which a durable connection to the structure of the heating plate or the auxiliary catalytic converter can be established. For this purpose, the ceramic can have, for example, an elliptical cross-section, and two regions preferably arranged on opposite regions of the outer periphery of the ceramic are provided with a metal layer. These metallized regions are used to connect the support element to the metal foil of the heating plate, for example, by welding.

[0020] Furthermore, it is advantageous that the heating disk has a second number of support elements formed by spacers, wherein the spacers space the wound layers adjacent to each other apart from each other and do not protrude beyond the heating disk in the axial extension direction of the heating disk, or only slightly protrude beyond the heating disk in the axial extension direction of the heating disk.

[0021] Different from the first support elements, the second support elements do not have a metal core protruding beyond the heating disk. The second support elements are not used for positioning the heating disk relative to other structures, but only for fixing the wound layers relative to each other. The second support elements, also referred to as spacers, are inserted into the air gap and connected to the adjacent wound layers. Thereby, the stability of the heating disk is improved, the air gap is reliably formed, and a discrete current bridge is formed between the wound layers or the wound layers are electrically insulated from each other according to the embodiment of the spacers.

[0022] Furthermore, it is advantageous that the first support element has an electrically insulating layer in one of its end regions, and the electrically insulating layer electrically insulates the core from the honeycomb body into which the corresponding end region is inserted. The electrically insulating layer can be formed of ceramic, for example.

[0023] It is also preferred that the first support element has an end region with an elliptical cross section, wherein the end region is formed by a metal core, a ceramic insulating layer, and two metal coating regions of the insulating layer, and the metal coating regions are not in electrically conductive contact with each other. The cross-sectional shape of the support element can be freely selected because it no longer has to be designed according to the corresponding geometry of the flow channels of the honeycomb body. However, an elliptical cross section is particularly advantageous for positioning in the air gap in order to form a sufficiently large contact area between the wound layer and the support element. In addition, the support element with an elliptical cross section has high strength.

[0024] It is also advantageous that the heating disk is fixed relative to the honeycomb body serving as an auxiliary catalytic converter by means of the first support elements, wherein the heating disk is fixed to the honeycomb body of the auxiliary catalytic converter by means of the section of the support pin protruding beyond the heating disk. The end region of the support element facing the auxiliary catalytic converter is inserted into the respective flow channels of the auxiliary catalytic converter, so that the support element in this region is preferably adapted to the cell geometry of the auxiliary catalytic converter.

[0025] Furthermore, it is advantageous that the first support element engages on one side into the air gap formed between the wound layers of the heating disk and engages on the other side into the flow channels of the honeycomb body of the auxiliary catalytic converter.

[0026] The object in terms of the method is achieved by a method having the features of claim 7.

[0027] One embodiment of the present invention relates to a method for manufacturing the device according to any one of the preceding claims, wherein the following method steps are performed:

[0028] a. Stack metal foils on top of each other to form a stacked layer,

[0029] b. Place the resulting stacked layer on a rotatably supported spiral disk, the spiral disk having components for positioning and / or fixing the stacked layer formed by the metal foils,

[0030] c. Insert at least one support element into the recesses provided in the spiral disk for this purpose,

[0031] d. Wind the stacked layer by rotating the spiral disk about at least one axis of rotation,

[0032] e. Weld the wound stacked layer and at least one inserted support element,

[0033] wherein the at least one support element can be inserted before or after winding of the stacked layer.

[0034] The heating disk is preferably wound by means of a turntable or a spiral disk. For this purpose, the stacked layer formed by the metal foils is screwed into the matrix applied to the spiral disk. The matrix formed by the wall sections forms the subsequent air gap when unscrewed.

[0035] The spiral disk preferably has a plurality of receiving parts in which support elements can be inserted respectively. These receiving parts are distributed on the spiral disk such that a favorable positioning of the support elements for each heating disk is achieved. The receiving parts are arranged in the region of the wall sections of the spiral disk forming the air gap in order to ensure that the support elements are positioned in the air gap in the manufactured heating disk.

[0036] Particularly advantageously, the spiral disk has at least one raised part which serves as a component for positioning the stacked layer, wherein the recesses for the at least one support element are arranged in the at least one raised part.

[0037] It is also advantageous that the spiral disk has wall elements protruding vertically from the bottom plate, and the wall elements occupy the space forming the air gap in the manufactured heating disk. The shape and structure of the heating disk are easily affected by the positioning and shaping of the wall elements.

[0038] It is also advantageous to use both a first support element formed by a support pin and a second support element formed by a spacer as support elements.

[0039] Advantageous refinements of the present invention are described in the dependent claims and the following description of the drawings. Description of the Drawings

[0040] The present invention will be described in detail below with reference to the accompanying drawings according to embodiments. Shown in the figures are:

[0041] Figure 1 A perspective view showing the spiral disk together with the support elements inserted into the recesses.

[0042] Figure 2 Showing according to Figure 1 A perspective view, in which the corresponding stacked layers have been screwed into the spiral disk, and it can be seen that the support elements are arranged in the region of the air gap.

[0043] Figure 3 Showing according to Figure 1 A cross-sectional view of the spiral disk, and

[0044] Figure 4 A top view showing two heating disks, where the left heating disk is of the prior art and the right heating disk is the heating disk according to the present invention, and its support elements are located in the air gap of the heating disk. Detailed Description of the Specific Embodiment

[0045] Figure 1 Showing the spiral disk 1, which has a plurality of support elements 2 inserted into the receiving portions. In the Figure 1 embodiment, the receiving portions are arranged such that the support elements 2 are arranged in rows. This is merely exemplary. Preferably, the support elements 2 are not arranged in rows distributed on the spiral disk 1, but are arranged according to the load distribution curve such that a stable heating disk is formed and at the same time an adapted connection with an auxiliary catalytic converter (not shown) can be produced.

[0046] The support elements 2 are on the one hand support pins 3 and on the other hand spacers 4. Different from Figure 1 , the support pins 3 and the spacers 4 can also be arranged alternately.

[0047] The wall section 5 is used to shape the stacked layer (not shown) that is screwed into the spiral disk 1.

[0048] Figure 2 Showing the spiral disk 1 according to Figure 1 . Here, the stacked layer 6 is screwed between the wall sections 5, which causes the stacked layer to deform and form the basic shape of the heating disk. The support elements 2 are connected to the stacked layer 6 through a welding process after winding, and thus the shape of the heating disk is fixed.

[0049] Figure 3The cross-section of the spiral disk 1 is shown. It can be seen here that the receiving portion for the support element is formed by the grooves in the spiral disk 1 and the notches in the wall section 5. This results in the support element 2 being able to be simply inserted into the spiral disk and fixed in its position by the wall section 5. Additionally, it can be seen that by the notches in the wall section 5, it is ensured that the support element 2 contacts the stacked layers screwed into the spiral disk 1 on both sides and thus a reliable connection can be established between the support element 2 and the stacked layers.

[0050] Figure 4 The top view of the end face of a conventional heating disk is shown on the left, where the support element is inserted into the flow channel of the heating disk and connected to the heating disk there.

[0051] In contrast, Figure 4 The top view of the end face of the heating disk 7 according to the present invention is shown on the right, where the support element 2 is only arranged in the air gap 8 of the heating disk 7 and connected to the metal foil of the heating disk 7 adjacent to the air gap 8.

[0052] Figures 1 to 4 The embodiments are particularly not restrictive features and are used to illustrate the inventive concept.

[0053] List of reference numerals:

[0054] 1 Spiral disk

[0055] 2 Support element

[0056] 3 Support pin

[0057] 4 Spacer

[0058] 5 Wall section

[0059] 6 Stacked layer

[0060] 7 Heating disk

[0061] 8 Air gap

Claims

1. An apparatus for purifying the exhaust gas of an internal combustion engine, the apparatus having a heating plate (7) formed by a honeycomb body of metal, wherein, The heating disk (7) is formed by a plurality of metal foils stacked on one another and wound around at least one axis of rotation, wherein the heating disk (7) has air gaps (8) between the winding layers, which air gaps space the winding layers apart from one another and define a flow path along the heating disk (7), wherein the honeycomb body has a plurality of flow channels through which the exhaust gas can flow, and wherein the heating disk (7) has a plurality of support elements (2). It is characterized in that the support elements (2) of the heating disk (7) are inserted into the air gaps (8) formed between the winding layers.

2. The device according to claim 1, characterized in that, The support elements (2) inserted into the air gaps are in contact with and durably connected to two respective winding layers that define the air gap in the radial direction.

3. The device according to any one of the preceding claims, characterized in that, At least a first number of support elements (2) are formed by support pins (3), wherein the support pins (3) have a pin-shaped core, the end sides of which are wrapped with an electrically insulating material, and wherein the electrically insulating material has two regions with a metal coating on its outer circumference, and wherein the two regions are not in electrically conductive contact with one another, and wherein the support pins (3) project beyond the heating disk in the axial extension direction of the heating disk.

4. The device according to any one of the preceding claims, characterized in that, The heating disk (7) has a second number of support elements (2) formed by spacers (4), wherein the spacers (4) space adjacent winding layers apart from one another and do not project beyond the heating disk (7) in the axial extension direction of the heating disk, or project only slightly beyond the heating disk in the axial extension direction of the heating disk.

5. The device according to any one of the preceding claims, characterized in that, The first support element (3) has an electrically insulating layer in one of its end regions, which electrically insulates the core from the honeycomb body into which the respective end region is inserted.

6. The device according to any one of the preceding claims, characterized in that, The heating disk (7) is fixed relative to the honeycomb body serving as an auxiliary catalytic converter by means of the first support elements (3), wherein the heating disk (7) is fixed to the honeycomb body of the auxiliary catalytic converter by means of the section of the support pins (3) that projects beyond the heating disk (7).

7. The device according to claim 6, characterized in that, The first support element (3) engages on one side into the air gap (8) formed between the winding layers of the heating disk (7), and on the other side into the flow channels of the honeycomb body of the auxiliary catalytic converter.

8. A method for manufacturing the device according to any one of the preceding claims, characterized in that, The following method steps are carried out: a. Stack the metal foils on one another to form a stacked layer (6). b. Place the resulting stacked layer (6) on a rotatably supported spiral disk (1), which spiral disk has means for positioning and / or fixing the stacked layer (6) formed by the metal foils. c. Insert at least one support element (2) into a recess provided in the spiral disk for this purpose. d. Wind the stacked layer (2) by rotating the spiral disk (1) around at least one axis of rotation. e. Weld the wound stacked layer (6) and at least one inserted support element (2). wherein the at least one support element (2) can be inserted before or after winding of the stacked layer (6).

9. The method according to claim 8, characterized in that, The spiral disk (1) has at least one projection (5), which at least one projection serves as a means for positioning the stacked layer (6), and wherein the recesses for the at least one support element (2) are arranged in the at least one projection.

10. The method according to any one of claims 8 or 9, characterized in that The spiral disk (1) has wall elements (5) projecting vertically from the base plate, and the wall elements occupy the space that forms an air gap in the fabricated heating disk.

11. The method according to any one of claims 8 to 10, characterized in that, Both the first support element formed by the support pins (3) and the second support element (2) formed by the spacers (4) are used as the support element (2).

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