Equipment with small cavities for exhaust aftertreatment

Abstract

The present invention relates to an exhaust aftertreatment device (1) for an internal combustion engine, the device having a honeycomb body (2) capable of flowing along a main flow direction, a ceramic pad (4), and at least one first housing (5, 10) for accommodating the honeycomb body (2), the ceramic pad (4) being arranged between the honeycomb body (2) and the housing (5, 10) and circumferentially surrounding the honeycomb body (2), the ceramic pad (4) being configured such that the cavity formed between the honeycomb body (2) and the first housing (5, 10) is completely filled by the ceramic pad (4). The invention also relates to a method of manufacturing the device, wherein the honeycomb body (2) is accommodated in a second housing (3), the honeycomb body (2) accommodated in the second housing (3) being circumferentially surrounded by the ceramic pad (4), the second housing (3) having a section (22) at an end region facing the gas inlet side (20), the structure of which differs from the structure of the rest of the second housing (3).

Description

Technical Field

[0001] The present invention relates to an exhaust aftertreatment device for an internal combustion engine, the device having a honeycomb structure capable of flowing along a main flow direction, a ceramic pad, and at least one first housing / shroud housing the honeycomb structure, wherein the ceramic pad is arranged between the honeycomb structure and the housing and circumferentially surrounds the honeycomb structure in the circumferential direction. The invention also relates to a method for manufacturing the device according to the invention, wherein the honeycomb structure (2) is housed in a second housing (3), and the honeycomb structure (2) housed in the second housing (3) is circumferentially surrounded by a ceramic pad (4). Background Technology

[0002] The honeycomb structure of a catalytic converter used for exhaust aftertreatment of internal combustion engines has multiple fluid channels that allow flow along the main flow direction. The honeycomb structure, particularly one made of metal, is formed from multiple smooth and / or at least partially structured metal foils, which are stacked and wound together to form the final honeycomb structure. A substrate formed of the metal foils is inserted into and permanently connected to the housing for stability and protection against mechanical interference.

[0003] In its simplest form, the outer shell is formed of a tube designed to house the substrate within it. Another function of the outer shell is to ensure airflow through the honeycomb structure, particularly preventing exhaust gas from flowing past the honeycomb structure.

[0004] On the one hand, the substrate must be permanently fixed within the outer casing, while on the other hand, the outer casing should be constructed as lightly as possible and therefore have thin walls. Some embodiments of the catalyst have an inner casing that directly houses the substrate. The inner casing is then supported relative to the outer casing or external sleeve by suitable supports.

[0005] A significant drawback of existing devices is the presence of air gaps between the various components of the catalyst, such as between the inner and outer shells, which are filled by the catalytically active material coated onto the substrate. These gaps can detach due to mechanical vibrations and thermal effects during operation, potentially leading to damage and / or deactivation of downstream catalysts used for exhaust aftertreatment. Furthermore, convection flow can occur in the space between the inner and outer shells if the flowing exhaust gas is accessible, significantly enhancing heat transfer between them and thereby markedly reducing the desired insulation effect. Consequently, the catalyst loses temperature and thus its effectiveness. Summary of the Invention

[0006] Therefore, the object of the present invention is to provide an apparatus for exhaust gas aftertreatment, wherein the substrate can be reliably housed within a housing, and at the same time, air gaps between the components are reduced or completely avoided to prevent undesirable separation of the coating material. The invention also relates to a method for manufacturing the apparatus according to the invention.

[0007] The objectives in terms of equipment are achieved by an equipment having the features of the present invention.

[0008] One embodiment of the present invention relates to an exhaust aftertreatment device for an internal combustion engine, the device having a honeycomb structure capable of flowing along a main flow direction, a ceramic pad, and at least one first housing housing the honeycomb structure, wherein the ceramic pad is arranged between the honeycomb structure and the housing and circumferentially surrounds the honeycomb structure, wherein the ceramic pad is configured such that the cavity formed between the honeycomb structure and the first housing is completely filled by the ceramic pad, wherein the honeycomb structure is housed in a second housing, and the honeycomb structure housed in the second housing is circumferentially surrounded by the ceramic pad, wherein the second housing has a section at an end region facing the gas inlet side, the structure of which differs from the structure of the rest of the second housing.

[0009] The pad is used to secure the honeycomb structure within a first housing, typically the outer casing of the device. The ceramic pad is designed to have thermal insulation properties, thus significantly reducing heat loss toward the outer casing. The ceramic pad is arranged completely around the honeycomb structure in the circumferential direction to ensure no air gaps are created between the honeycomb structure and the outer casing. The ceramic pad is capable of absorbing mechanical stress and, if necessary, partially reducing mechanical stress through compression. These mechanical stresses are particularly likely to arise from the expansion of the honeycomb matrix under thermal influence.

[0010] The ceramic pad preferably has a thickness of 2 mm to 5 mm and, in addition to the strong thermal insulation mentioned above, also has electrical insulation properties, which is particularly advantageous when the honeycomb is electrically heated or when honeycombs are in conductive contact with each other.

[0011] This is particularly advantageous because manufacturing can be improved through the second housing.

[0012] Preferably, an inner shell and a second shell disposed between the honeycomb and the ceramic pad can be subjected to a radial force and thus be targeted to widen to a predetermined inner cross-section. This process is also known as the alignment of the inner shell. In this way, a certain prestress can be generated between the inner shell and the ceramic pad, and at the same time, an inner cross-section of the inner shell that is conducive to accommodating the honeycomb can be created.

[0013] The section at the gas inlet side is specifically formed by an annular region extending from the gas inlet side along the axial extension of the honeycomb structure. This section may differ from the rest of the second housing in, for example, in material selection, material thickness, and material porosity. In particular, structures that cause changes in heat capacity can be introduced into this section.

[0014] Particularly advantageous is that the second housing has openings in this section, which are arranged circumferentially spaced apart from each other on the gas inlet side. The openings can be, for example, formed by rectangular windows arranged at intervals. Alternatively, circular or elliptical holes arranged in a predetermined pattern can be provided. For example, the number or size of the holes can be specified to vary along the axial extension.

[0015] Also suitable is that a section of the second housing at the gas inlet side is formed of a different material than the rest of the second housing, wherein the different material has a significantly reduced heat capacity. Preferably, for example, a metal mesh with openings in its structure can be provided. Alternatively, a material with a low heat capacity can also be selected.

[0016] Furthermore, it is preferable that the porosity of a section of the second shell is 50% to 90% compared to the porosity of the rest of the second shell. By changing the porosity, in particular reducing the heat capacity of the second shell, it is beneficial to heat the catalytically active structure of the honeycomb structure.

[0017] Furthermore, it is advantageous that the section of the ceramic pad on the gas inlet side is at least partially directly exposed to the fluid flowing in the honeycomb.

[0018] Furthermore, it is preferable that the section of the second housing has an axial extension length of 20 mm to 50 mm when viewed from the gas inlet side. Such an axial extension length has proven advantageous, particularly in devices used for exhaust aftertreatment in passenger vehicles.

[0019] It is also advantageous that the second housing is significantly thinner than the first housing, wherein, preferably, the thickness of the first housing is 4 to 20 times that of the second housing. This is advantageous because the heat capacity is thus minimized.

[0020] Preferably, the first shell forming the outer casing of the device has a thickness of 2 mm to 5 mm. This is necessary for both hermetically sealing the device and providing sufficient mechanical stability. The second shell, serving as the inner shell between the honeycomb cells and the ceramic pad, preferably has a thickness of 0.1 mm to 0.55 mm. The inner shell should be particularly lightweight and capable of being widened or aligned with relatively small forces, thereby allowing for the formation of a suitable cross-section to accommodate the honeycomb cells.

[0021] A preferred embodiment is characterized in that the first housing has a radially everted section. This everted region is advantageous because, when viewed from the inside, it forms a radially outwardly shaped, circumferentially surrounding groove into which the ceramic pad can be accommodated, particularly with most or even entirely of its radial extension. Additional fixation of the ceramic pad, and thus additional fixation of the honeycomb structure, can also be achieved by limiting this eversion in the axial direction.

[0022] Preferably, the ceramic pad is accommodated in the radially outward-curving area. This is particularly advantageous for both radial fixation of the ceramic pad and axial fixation within the first housing or outer casing.

[0023] The methodological objective is achieved by a method having the features of the present invention.

[0024] One embodiment of the present invention relates to a method for manufacturing a device according to the invention, wherein a honeycomb is inserted into a ceramic pad, wherein a ceramic pad having the housed honeycomb is inserted into a first housing, wherein at least one radially acting force is applied to the first housing, the ceramic pad, and / or the honeycomb.

[0025] By applying a force acting in the radial direction, individual components can be widened or compressed. This, in any case, strengthens the contact between adjacent components.

[0026] The application of a radially acting force can be used for so-called calibration. Here, at least one of the components is widened or compressed to a specified degree. This, for example, can compensate for differences in the cross-sections of the individual components and achieve a tight fit between the components.

[0027] Furthermore, it is advantageous that the device has a second housing, wherein the outer diameter of the second housing is less than or equal to the inner diameter of the ceramic pad, wherein the second housing is radially widened after being inserted into the ceramic pad, thereby causing the ceramic pad to be compressed in the radial direction and / or generating a force acting from the ceramic pad on the first housing in the radial direction.

[0028] In the first arrangement, a ceramic pad is inserted into a first housing forming the outer shell. Then, a second housing, i.e., an inner housing, is inserted into the ceramic pad. Here, the outer diameter of the inner housing is smaller than the inner diameter of the ceramic pad. A radially outward force is then applied from the inside to the inner housing, thereby expanding the inner housing to a predetermined extent. Alternatively, a component force can be applied to the ceramic pad, thereby compressing it. Depending on the design, a component force can also be applied to the outer shell.

[0029] The inner shell, widened to a certain extent, then accommodates the honeycomb structure, which is subsequently brazed to the inner shell. This widening ensures a tight fit between the inner shell, ceramic pad, and outer shell, preventing air gaps between components. Therefore, cavities that might undesirably be filled by the coating material during the subsequent application of the catalytically active coating to the honeycomb structure are avoided.

[0030] Therefore, it is particularly preferable that no coating material accumulates in the cavities outside the honeycomb structure to prevent undesirable separation of the coating material during subsequent operation. Because the coating material is catalytically active, it can undergo chemical reactions, which can potentially damage downstream components, especially in interaction with other coating materials along the flow direction used for exhaust aftertreatment. This is known as poisoning, as it can severely impair the exhaust aftertreatment capabilities of downstream components.

[0031] Furthermore, it is advantageous that the honeycomb structure is fixed by multiple solder points after winding to prevent it from fanning out, and is inserted into a ceramic pad having an inner diameter that is the same as the outer diameter of the fixed honeycomb structure. The ceramic pad with the honeycomb structure is inserted into a first housing having an inner diameter that is larger than the outer diameter of the ceramic pad. After the ceramic pad is inserted, a radial force is applied to the first housing from the outside, thereby reducing the diameter of the first housing.

[0032] An alternative method specifies, for example, using welding points to secure the wound honeycomb structure to the substrate. This prevents the substrate from curling up or fanning out. The honeycomb structure is inserted into a ceramic pad designed to fit precisely to accommodate the honeycomb structure. The assembly consisting of the honeycomb structure and the ceramic pad is then inserted into a housing having an inner diameter larger than the inserted assembly. Here, the housing can optionally have outwardly pointing flanges or can be constructed as a column.

[0033] A radially inward force is then applied to the housing, which compresses the housing and thus presses it firmly against the ceramic pad.

[0034] It is also advantageous to apply a radial force to the first housing, causing the ceramic pad to be compressed within the first housing both radially and axially. This can be advantageously achieved, particularly when the outer housing has an outwardly pointing flared portion, into which the ceramic pad and honeycomb are inserted. In particular, if the ceramic pad abuts against the sidewall of the outer housing extending from the flared section to the non-flared section, the outer housing with the flared section can also be easily fixed in the axial direction.

[0035] Furthermore, it is advantageous to apply radial force to the radially outward-flaring section of the first housing. This is particularly advantageous because a ceramic pad with a honeycomb structure is arranged in this section.

[0036] Advantageous improvements of the invention are described in the dependent claims and the following description of the drawings. Attached Figure Description

[0037] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. In the drawings: Figure 1 The diagram shows a schematic view, including a honeycomb structure housed within an inner housing and a ceramic pad housed within an outer housing. Figure 2 Showing the corresponding Figure 1 The schematic diagram shows that the outer shell has a section that flips outwards radially. Figure 3 Showing the corresponding Figure 2 The schematic diagram shows that no inner shell is arranged between the ceramic pad and the honeycomb structure. Figure 4 A perspective cross-sectional view is shown through a second housing that serves as an inner housing, the second housing having a structure different from the rest of the second housing in the section located on the gas inlet side. Detailed Implementation

[0038] Figure 1 A device 1 for exhaust aftertreatment is shown. The device 1 has a honeycomb structure 2 housed in an inner housing 3. The honeycomb structure 2 and the inner housing 3 are housed in a ceramic pad 4. The ceramic pad 4 is in turn housed in an outer housing 5, which can form a shell visible from the outside.

[0039] Figure 1 A cross-sectional view is shown passing through the central axis of the honeycomb 2. The inner shell 3, ceramic pad 4, and outer shell 5 are all annular elements surrounding the cylindrical honeycomb. In alternative designs, cross-sectional shapes other than circular cross-sections can also be chosen.

[0040] A heating element 6, which is electrically heated, is shown on the left side of the honeycomb cell 2. This heating element is connected to the honeycomb cell 2 via a support pin 7. The heating element 6 can be electrically contacted via electrical feeders / connectors 8 and 9. The heating element 6 can be heated using an ohmic resistance by applying current to it. The heating element 6 can be supported in front of or behind the honeycomb cell 2 along the current flow direction.

[0041] Figure 1The outer casing 5 is tubularly constructed and has a cross-section that remains constant along its length. Preferably, the inner casing 3 is subjected to a radially outward force to compress the ceramic pad 4 in the radial direction and establish pressure on the outer casing 5. This allows the assembly consisting of the honeycomb 2, the inner casing 3, and the ceramic pad 4 to be fixed relative to the outer casing 5. Alternatively, it can be specified that after the honeycomb 2 is inserted, the outer casing 5 is subjected to a radially inward force to compress the entire device and fix the various components to each other. Alternatively or additionally, the individual components or all components may be connected to each other by a material-locking method such as brazing or a similar method.

[0042] Figure 2 Showing with Figure 1 Similar structure. Therefore, the same elements are labeled with the same reference numerals. Figure 1 Instead, the outer casing 10 is designed such that it has a radially outwardly folded section 11. This outwardly folded section 11 is preferably constructed to completely surround the periphery in the circumferential direction and forms a receiving area 12 for the ceramic pad 4 inside the outer casing 10.

[0043] The ceramic pad 4 can be fixed internally by applying a radially inward force to the housing 10. The ceramic pad 4 can also be additionally fixed in the axial direction of the device 1 by arranging it within the receiving area 12 formed by the outwardly turned portion 11.

[0044] Figure 3 Show Figure 2 An alternative design for the equipment. With Figure 2 The difference lies in Figure 3 The inner shell 3 is not included. According to... Figure 3 In this embodiment, the wound honeycomb 2 is fixed by multiple solder points to prevent it from fanning out or rolling up.

[0045] Then, the honeycomb 2 is inserted into the ceramic pad 4 and into the receiving area 12 of the outer casing 10. By applying a radially inward force, the honeycomb 2, together with the ceramic pad 4, is fixed in the outer casing 10.

[0046] Through Figures 1 to 3 Applying radial force to the device allows for tight compression and thus avoids the formation of air gaps between components. Therefore, coating the honeycomb with a catalytically active surface coating no longer results in coating material deposition in the air gaps.

[0047] Figure 4 The inner housing 3 is shown, having a segment 22 extending axially from the gas inlet side 20 along a length indicated by reference numeral B. The inner housing 3 is inserted into the outer housing 5, wherein the outer housing 5 forms a cavity into which the ceramic gasket 4 is inserted.

[0048] exist Figure 4 In one embodiment, segment 2 has a plurality of rectangular openings 21. These openings are arranged spaced apart from each other in the circumferential direction and thus significantly reduce the heat capacity of the second housing 3 in segment 22.

[0049] exist Figure 4 In an embodiment exemplifying the subject matter of the invention, the rectangular opening 21 has a width C along the circumferential direction, which is preferably 30 mm. The axial extension of the opening 21 is 30 mm in this embodiment. The circumferential distance D is 5 mm in this embodiment. Here, the distance A between the edge of the second housing 3 and the opening 21 at the gas inlet side 20 is preferably 7 mm. The example shown here includes 10 openings.

[0050] Different design schemes can be set. Figure 4 The embodiment illustrates a possible design scheme.

[0051] Different features of the various embodiments can also be combined with each other. Therefore, specifically, the outer shell with the everted portion can be combined with the inner shell.

[0052] Figures 1 to 4 The embodiments described herein are not limiting features, but are used to illustrate the inventive concept.

[0053] List of reference numerals in the attached diagram: 01 Equipment 02 Honeycomb 03 Inner shell 04 Ceramic Pad 05 Outer shell 06 Heating element 07 Support pin 08 Electrical connector 09 Electrical connector 10. Outer shell 11. Eversion 12 Accommodation Area 20 Gas inlet side 21 Opening 22 sections A. Distance from the gas inlet side to the opening B Opening length C Opening width D Opening distance

Claims

1. An exhaust aftertreatment device (1) for an internal combustion engine, the device having a honeycomb structure (2) capable of flowing along a main flow direction from the gas inlet side to the gas outlet side, a ceramic pad (4), and at least one first housing (5, 10) for receiving the honeycomb structure (2), wherein, A ceramic pad (4) is arranged between the honeycomb body (2) and the shell (5, 10) and surrounds the honeycomb body (2) in a circumferential direction. The ceramic pad (4) is configured such that the cavity formed between the honeycomb body (2) and the first shell (5, 10) is completely filled by the ceramic pad (4). The honeycomb body (2) is housed in the second shell (3), and the honeycomb body (2) housed in the second shell (3) is surrounded by the ceramic pad (4) in a circumferential direction. Its features are, The second housing (3) has a section (22) at its end region facing the gas inlet side (20), the structure of which differs from the structure of the rest of the second housing (3), and The second housing (3) has openings (21) in the section (22), which are arranged circumferentially spaced from each other at the gas inlet side (20).

2. The device (1) according to claim 1, characterized in that, The section (22) of the second housing (3) at the gas inlet side (20) is formed of a different material than the rest of the second housing (3), wherein the different material has a significantly reduced heat capacity.

3. The device (1) according to claim 2, characterized in that, The porosity of the section (22) of the second housing (3) is 50% to 90% of the porosity of the rest of the second housing (3).

4. The device (1) according to any one of claims 1 to 3, characterized in that, The ceramic pad (4) is at least partially directly exposed to the fluid flowing in the honeycomb (2) in the section (22) at the gas inlet side (20).

5. The device (1) according to any one of claims 1 to 3, characterized in that, Viewed from the gas inlet side (20), the section (22) of the second housing (3) has an axial extension length of 20 mm to 50 mm.

6. The device (1) according to any one of claims 1 to 3, characterized in that, The second shell (3) is significantly thinner than the first shell (5, 10).

7. The device (1) according to claim 6, characterized in that, The thickness of the first shell (5, 10) is 4 to 20 times that of the second shell (3).

8. The device (1) according to any one of claims 1 to 3, characterized in that, The first housing (10) has a section (11) that is turned outward in the radial direction.

9. The device (1) according to claim 8, characterized in that, The region (12) that is turned outward in the radial direction contains a ceramic pad (4).

10. A method for manufacturing the device (1) according to any one of claims 1 to 9, Its features are, The honeycomb (2) is inserted into the ceramic pad (4), wherein the ceramic pad (4) having the honeycomb (2) is inserted into the first housing (5, 10), wherein at least one radially acting force is applied to the first housing (5, 10), the ceramic pad (4) and / or the honeycomb (2). The device (1) has a second housing (3), and the method further includes: The second housing (3) has a section (22) at the end region facing the gas inlet side (20), the structure of which differs from the structure of the rest of the second housing (3), and The second housing (3) has openings (21) in the section (22), which are arranged circumferentially spaced apart from each other at the gas inlet side (20).

11. The method for manufacturing equipment (1) according to claim 10, characterized in that, The outer diameter of the second housing (3) is less than or equal to the inner diameter of the ceramic pad (4), wherein the second housing (3) is radially widened after being inserted into the ceramic pad (4), thereby causing the ceramic pad (4) to be compressed in the radial direction and / or generating a force acting from the ceramic pad (4) on the first housing (5, 10) in the radial direction.

12. The method according to claim 10, characterized in that, After being wound, the honeycomb (2) is fixed by multiple solder points to prevent it from spreading out in a fan shape and is inserted into a ceramic pad (4), wherein the inner diameter of the ceramic pad (4) is the same as the outer diameter of the fixed honeycomb (2), wherein the ceramic pad (4) with the honeycomb (2) is inserted into a first housing (5, 10), wherein the inner diameter of the first housing is larger than the outer diameter of the ceramic pad (4), wherein after the ceramic pad (4) is inserted, a radial force is applied from the outside to the first housing (5, 10), thereby reducing the diameter of the first housing (5, 10).

13. The method according to claim 12, characterized in that, A radial force is applied to the first housing (5, 10) such that the ceramic pad (4) is compressed in the first housing (5, 10) both in the radial and axial directions.

14. The method according to claim 13, characterized in that, A radial force is applied to the radially outward-curving section (11) of the first housing (10).

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