Apparatus for exhaust gas aftertreatment and method of manufacture

Abstract

The present invention relates to a device for purifying the exhaust gases of an internal combustion engine, the device comprising a heating disk (7) made of a metallic honeycomb body, the heating disk (7) being formed from a plurality of metal sheets stacked and wound around at least one axis of rotation, the heating disk (7) having air gaps (8) between the winding layers, the air gaps (8) holding the winding layers at a distance from one another to define flow paths along the heating disk (7), the honeycomb body having a plurality of flow passages through which the exhaust gas can flow, and the heating disk (7) having a plurality of support elements (2) that are inserted into the air gaps (8) formed between the winding layers.

Description

[Technical Field]

[0001] The present invention relates to an apparatus for purifying exhaust gases of an internal combustion engine, the apparatus comprising a heating disk formed from a metallic honeycomb body, the heating disk being formed from a plurality of metal sheets stacked and wound around at least one axis of rotation, the heating disk having air gaps between the winding layers that space the winding layers apart and define flow paths along the heating disk, the honeycomb body having a plurality of flow passages through which the exhaust gases can flow, and the heating disk having a plurality of support elements. Furthermore, the present invention relates to a method for manufacturing the apparatus. [Background technology]

[0002] In the prior art, support pins are known for connecting an electric heating disk, which is formed as a metal honeycomb body, to another honeycomb body of a so-called supported catalyst. The support pins are inserted into the cells of each honeycomb body and permanently connected to these honeycomb bodies by soldering. In this case, the support pins, on the one hand, ensure the spatial positioning of the heating disk relative to the supported catalyst and, on the other hand, ensure the electrical isolation between the two honeycomb bodies.

[0003] The permanent connection between the honeycomb body and the support pin is then preferably made between the metal sleeve of the support pin or the metal core of the support pin and the corrugated metal sheet of the respective honeycomb body.

[0004] Depending on the design of the heating disk, more or less a number of support pins are provided, which are sometimes arranged in multiple rows, and in this case the support pins are arranged in such a way that the highest possible durability can be expected during operation, taking into account, in particular, the thermal and mechanical loads.

[0005] A disadvantage of the prior art devices is, inter alia, the need for a large number of support pins, which leads to high manufacturing costs. Furthermore, a disadvantage of previously known heating disks made of a metal honeycomb body is that, due to the electrical insulation of the individual layer units from one another, air gaps must be formed between the individual layers, which makes the honeycomb body unstable and susceptible to harmful vibration phenomena, particularly due to its low natural frequency. Furthermore, the air gaps form a kind of bypass through which exhaust gases can unintentionally flow past the heating body.

[0006] Furthermore, for a good fit between the support pin and the corrugated layer of the honeycomb body, the corrugated layer must be precisely adjusted with respect to its cell density and profile, since otherwise defects and non-bonds may occur during the brazing process, which would undesirably impair the structural integrity.

[0007] Furthermore, the support pins lead to blockage of the respective cells in which they are inserted, so that these cells or flow channels are no longer available for exhaust gas aftertreatment. Summary of the Invention [Problem to be solved by the invention]

[0008] Invention disclosure, problem, solution, advantages The object of the present invention is therefore to provide an apparatus with an electrically heatable heating disk that has an optimized structure and can be connected to a supported catalyst connected upstream or downstream, if necessary using suitable support elements. [Means for solving the problem]

[0009] The problem with the device is solved by a device having the features of claim 1.

[0010] One embodiment of the present invention relates to an apparatus for purifying exhaust gases from an internal combustion engine, the apparatus comprising a heating disk formed from a metallic honeycomb body, the heating disk being formed from a plurality of metal sheets stacked and wound around at least one axis of rotation, the heating disk having air gaps between the winding layers, the air gaps holding the winding layers spaced apart from one another to define flow paths along the heating disk, the honeycomb body having a plurality of flow passages through which exhaust gases can flow, and the heating disk having a plurality of support elements, the support elements of the heating disk being inserted into the air gaps formed between the winding layers.

[0011] By inserting support elements into the air gaps formed between the individual winding layers, a bond is formed between the individual winding layers and the individual winding layers can be supported relative to one another. Due to this mutual support, the stability of the heating disk formed in this way is significantly increased, which in turn improves its durability, in particular with respect to mechanical loads on the heating disk that may arise from vibrations of the heating disk itself and / or vibrations of other components in the exhaust gas path. In particular, due to the insertion of support elements and the mutual bonding of the winding layers, the number of different bending natural frequencies of the heating disk is reduced.

[0012] Additionally, the increased stability of the heater disk allows for the saving of many of the support elements typically used, since the number of bond points to the supported catalyst that support the heater disk can be dramatically reduced.

[0013] Preferably, the support elements are inserted only into the air gap, which offers several advantages. On the one hand, the flow passages formed in the heating disk are not blocked by the support elements. Therefore, all flow passages can be passed through by exhaust gas. This improves the heating disk's intended purpose, i.e., heating of the exhaust gas. Furthermore, the support elements do not need to be adapted to the geometry of the formed flow passages. This reduces the number of various parts, which allows for easier manufacturing. Furthermore, in this way, heating disks with a low cell count, e.g., only 50 or 75 cells per square inch (cpsi), such as those used for trucks, can be positioned using standard support elements that are usually too narrow for the cell size of the heating disk.

[0014] Furthermore, the air gap, through which the exhaust gases would otherwise flow and which would inevitably result in an undesired bypass effect, is at least partially blocked by the support element. Furthermore, due to the positioning of the support element according to the invention, a more uniform heating of the heating disk is possible.

[0015] One preferred embodiment is characterized in that the support elements inserted into the air gap are in contact with each of the two winding layers that radially define the air gap and are permanently connected to these winding layers. This results in high stability of the heater disk on the one hand, and allows for a targeted influence on the formation of the current path that results from the current between the two electrical connections of the heater disk on the other hand. By selecting support elements that do not have electrical insulation, the two winding layers can be brought into conductive contact with each other, thereby widening the current path. This also allows for targeted application of a stronger current to certain areas of the heater disk, for example, to ensure improved heat distribution across the heater disk. The electrically conductive support elements form so-called discrete current bridges that influence the current flow.

[0016] The winding layers can be intentionally electrically insulated from one another, for example by the selection of a supporting element which has an electrically insulating effect, based on a suitable coating or an electrically insulating layer.

[0017] It may also be preferred if at least one first number of support elements is formed by a support pin, the support pin having a pin-shaped core, the core being surrounded at its end by an electrically insulating material, the outer surface of which has two areas with a metallic covering, which areas are not in conductive contact with each other, and the support pin protruding beyond the heating disk in the axial extension direction of the heating disk.

[0018] The first support elements are configured like conventional support pins. They are advantageous in that one end region of the first support elements is inserted into the heating disk, more precisely, into the air gap of the heating disk, and the opposite end region is connected to a support structure, such as a supported catalyst connected upstream or downstream. Depending on the application, the support pins can be electrically insulating or conductive. Insulating support pins generally have a metal core, the end regions of which are surrounded by an electrically insulating layer. In this case, this insulating layer, typically ceramic, has two disconnected regions with a metallic coating, through which a durable connection to the heating disk or the supported catalyst structure can be formed. For this purpose, the ceramic can have, for example, an elliptical cross section. In this case, a metallic coating is applied to two regions of the ceramic outer periphery, preferably two regions opposite each other. These metal-coated regions are used to connect the support elements to the metal sheet of the heating disk, for example, by soldering.

[0019] It is furthermore advantageous if the heating disk has a second number of support elements formed by spacers which hold adjacent winding layers at a distance from one another and which do not protrude, or only slightly protrude, beyond the heating disk in the axial extension direction of the heating disk.

[0020] Unlike the first support element, the second support element does not have a metal core that protrudes beyond the heating disk. It is not used to position the heating disk relative to another structure; it only serves to secure the winding layers relative to each other. The second support element, also known as a spacer, is inserted into the air gap and connected to adjacent winding layers. This increases the stability of the heating disk, ensures the air gap, and, depending on the spacer configuration, either creates a discrete current bridge between the winding layers or electrically insulates the winding layers from each other.

[0021] Furthermore, it is advantageous if the end regions of the first support elements have an electrically insulating layer that electrically insulates the core from the honeycomb body into which the respective end regions are inserted. The electrically insulating layer can be formed, for example, from ceramic.

[0022] It may also be advantageous if the first support element has an end region with an elliptical cross section, which end region is formed by a metal core, a ceramic insulating layer, and two metallized regions of the insulating layer, the metallized regions not being in conductive contact with each other. The cross-sectional shape of the support element can be freely selected, since it no longer has to be formed in accordance with the respective 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 create a sufficiently large contact surface between the winding layer and the support element. Furthermore, support elements with an elliptical cross section have a high strength.

[0023] Preferably, the heating disk is fixed relative to the honeycomb body used as the supported catalyst by the first support elements, and the heating disk is fixed to the honeycomb body of the supported catalyst by sections of the support pins that protrude beyond the heating disk. The end regions of the support elements facing the supported catalyst are inserted into the individual flow channels of the supported catalyst, and therefore the support elements are preferably adapted to the geometric shape of the cells of the supported catalyst in this region.

[0024] Furthermore, it is advantageous if one side of the first support element is engaged in an air gap formed between the winding layers of the heating disk, and the other side of the first support element is engaged in a flow passage provided in the honeycomb body of the supported catalyst.

[0025] The problem with the method is solved by a method having the features of claim 7.

[0026] An embodiment of the invention is a method for manufacturing a device according to any one of claims 1 to 7, comprising the following method steps: a. Stacking metal sheets to form a single layer stack; b. placing the formed layer stack on a rotatably supported spiral table having means for positioning and / or fixing the position of the formed layer stack from the metal sheet; c. inserting at least one support element into a recess provided for this purpose in the spiral table; d. winding the layer stack by rotating the spiral table about at least one axis of rotation; e. Brazing the wound layer stack to at least one inserted support element. performing a method step comprising: The method relates to a method in which the insertion of the at least one support element can take place before or after winding the layer stack.

[0027] The heating disk is preferably wound using a turntable or spiral table, for which the layer stack formed from the metal sheet is wound into a matrix mounted on the spiral table, the matrix formed from the wall sections forming the subsequent air gaps when wound.

[0028] The spiral table preferably has a number of receiving recesses into each of which a support element can be inserted. The receiving recesses are distributed over the spiral table in such a way that an advantageous positioning of the support elements is achieved for each heating disk. The receiving recesses are arranged in the region of the wall section of the spiral table that forms the air gap, thereby ensuring that the support elements are positioned in the air gap in the finished heating disk.

[0029] It is particularly advantageous if the spiral table has at least one raised portion, which is used as a means for positioning the layer stack, and if a cutout for at least one support element is arranged in the raised portion.

[0030] It is also advantageous if the spiral table has wall elements protruding perpendicularly from the base plate, the wall elements occupying the space that forms the air gap in the finished heating disk. By positioning and shaping the wall elements, the shape and structure of the heating disk can be easily influenced.

[0031] Furthermore, it is preferred if both first support elements formed by support pins and second support elements formed by spacers are used as support elements.

[0032] The dependent claims and the following description of the drawings describe advantageous refinements of the invention.

[0033] The invention will now be described in more detail with reference to the accompanying drawings, in which: FIG. [Brief explanation of the drawings]

[0034] [Figure 1] FIG. 1 is a perspective view of a spiral table with support elements inserted into the cutouts. [Figure 2] 2 shows the perspective view shown in FIG. 1 with the corresponding layer stack wound in the spiral table and the support elements arranged in the area of ​​the air gap. [Figure 3] FIG. 2 is a cross-sectional view of the spiral table shown in FIG. [Figure 4] 1 is a plan view showing two heating disks, the heating disk on the left showing the prior art and the heating disk on the right showing a heating disk according to the invention with a support element in the air gap of the heating disk. DETAILED DESCRIPTION OF THE INVENTION

[0035] FIG. 1 shows a spiral table 1. The spiral table 1 has a number of support elements 2, which are inserted into receptacles. In the embodiment shown in FIG. 1, the receptacles are arranged so that the support elements 2 are arranged in rows. This is merely an example. Preferably, the support elements 2 are not distributed in rows across the spiral table 1, but are arranged in such a way that they correspond to the load profile and simultaneously provide a stable heating disk and a snap-fit ​​connection to the supported catalyst (not shown).

[0036] The support elements 2 are, on the one hand, support pins 3 and, on the other hand, spacers 4. In contrast to the embodiment shown in Figure 1, the support pins 3 and spacers 4 may also be arranged alternately.

[0037] The wall section 5 is used to give shape to a layer stack (not shown) that is wound into the spiral table 1 .

[0038] Figure 2 shows the spiral table 1 shown in Figure 1, in which a layer stack 6 is wound between wall sections 5, which causes deformation of the layer stack and the basic shape of the heating disk. By a brazing process carried out following the winding, the support element 2 is connected to the layer stack 6, and the heating disk is thus fixed in its shape.

[0039] Figure 3 shows a cross-section of the spiral table 1. As can be seen from Figure 3, the accommodation for the support element is formed by a recess in the spiral table 1 and a cutout in the wall section 5. This results in the support element 2 being easily inserted into the spiral table 1 and being fixed in place by the wall section 5. As can also be seen from the drawing, the cutout in the wall section 5 ensures that the support element 2 comes into contact on both sides with the layer stack wound in the spiral table 1, thus forming a reliable bond between the support element 2 and the layer stack.

[0040] The left side of FIG. 4 shows a plan view of the end face of a conventional heater disk, in which the support element is inserted into a flow passage provided in the heater disk and is connected thereto.

[0041] In contrast to this, the right side of Figure 4 shows a plan view of the end face of a heating disk 7 according to the present invention, in which the support element 2 is arranged only in the air gap 8 of the heating disk 7 and is connected to a metal sheet of the heating disk 7 that is in contact with the air gap 8.

[0042] The embodiments of FIGS. 1 to 4 are not particularly limiting and serve to clarify the concept of the invention. [Explanation of symbols]

[0043] 1 Spiral Table 2 Support elements 3 support pins 4 spacers 5 wall division 6-layer stack 7 Heating disc 8 Air Gap

Claims

1. 1. An apparatus for purifying exhaust gases of an internal combustion engine, comprising a heating disk (7) formed from a metal honeycomb body, the heating disk (7) being formed from a plurality of metal sheets stacked and wound around at least one axis of rotation, the heating disk (7) having air gaps (8) between the winding layers which space the winding layers apart from one another and define flow paths along the heating disk (7), the honeycomb body having a plurality of flow passages through which exhaust gases can flow, and the heating disk (7) having a plurality of support elements (2), 1. A device for purifying exhaust gases of an internal combustion engine, characterized in that the support element (2) of the heating disc (7) is inserted into the air gap (8) formed between the winding layers.

2. 2. The device according to claim 1, wherein the support element (2) inserted into the air gap is in contact with each of the two winding layers radially defining the air gap and is permanently connected to said winding layers.

3. 3. The device according to claim 1, wherein at least one of the first number of support elements (2) is formed by a support pin (3), which has a pin-shaped core, which is surrounded at its end by an electrically insulating material, the outer surface of which has two areas with a metallic coating, which are not in conductive contact with each other, and which protrude beyond the heating disk in the axial extension direction of the heating disk.

4. 4. The device according to claim 1, wherein the heating disk (7) has a second number of support elements (2) formed by spacers (4), which hold the adjacent winding layers at a distance from each other and which do not protrude or only slightly protrude beyond the heating disk (7) in the axial extension direction of the heating disk.

5. 5. The device according to claim 1, wherein the end regions of the first support elements (3) have an electrically insulating layer which electrically insulates the core from the honeycomb body into which the respective end regions are inserted.

6. 6. The device according to claim 1, wherein the heating disk (7) is fixed in position relative to a honeycomb body used as a supported catalyst by the first support element (3), and the heating disk (7) is fixed in position relative to the honeycomb body of the supported catalyst by sections of the support pins (3) that protrude beyond the heating disk (7).

7. 7. The device according to claim 6, wherein one side of the first support element (3) is engaged in the air gap (8) of the heating disk (7) formed between the winding layers, and the other side of the first support element (3) is engaged in a flow passage provided in the honeycomb body of the supported catalyst.

8. A method for manufacturing a device according to any one of claims 1 to 7, comprising the steps of: a. Stacking metal sheets to form a layer stack (6); b. placing the formed layer stack (6) on a rotatably supported spiral table (1) having means for positioning and / or fixing the position of the layer stack (6) formed from the metal sheet; c) inserting at least one support element (2) into a recess provided for this purpose in the spiral table; d. Winding the layer stack (2) by rotating the spiral table (1) about at least one axis of rotation; e. Brazing the wound layer stack (6) to the inserted at least one support element (2). performing a method step comprising:

10. A method according to claim 9, wherein the insertion of said at least one support element (2) can take place before or after the winding of said layer stack (6).

9. 9. The method according to claim 8, characterized in that the spiral table (1) has at least one raised portion (5), which is used as a means for positioning the layer stack (6), and the cutout for the at least one support element (2) is arranged on the raised portion.

10. 10. The method according to claim 8 or 9, characterized in that the spiral table (1) has wall elements (5) protruding perpendicularly from a base plate, which wall elements (5) occupy a space that forms the air gap in the finished heating disk.

11. 11. The method according to claim 8, wherein both first support elements formed by support pins (3) and second support elements (2) formed by spacers (4) are used as the support elements (2).

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