Apparatus for exhaust aftertreatment

Abstract

The invention relates to a device for the exhaust gas aftertreatment of an internal combustion engine, comprising a metallic main body (5) through which a flow can flow in a main flow direction and which is inserted into a sleeve (1, 11), the main body (5) being formed from a stack of layers formed from a plurality of metal foils, the stack being wound around at least one winding point, at least some of the metal foils are at least partially textured, whereby a plurality of flow channels are formed between the metal foils, which flow channels can be flowed through in a main flow direction from the gas inlet side to the gas outlet side of the main body (5), an inner tube (6) is arranged between the sleeve (1, 11) and the main body (5), an air gap (7) is formed between the inner tube (6) and the sleeve (1, 11). In addition, a separating layer can be arranged on the inner side of the sleeve (1, 11), for example made of a metal foil (3) having a spacer (4).

Description

Technical Field

[0001] The present invention relates to a device for post-treatment of exhaust gas of an internal combustion engine, which has a metallic substrate that can be flowed through along a main flow-through direction, and the substrate is inserted into a sleeve. The substrate is formed by a stack of layers / layer stacks, the stack of layers is formed by a plurality of metal foils, and the stack of layers is wound around at least one winding point. At least some of the metal foils are at least partially textured / structured, whereby a plurality of flow channels are formed between the metal foils, and the flow channels can be flowed through along the main flow-through direction from the gas inlet side of the substrate towards the gas outlet side. Background Art

[0002] The honeycomb body of a catalytic converter for post-treatment of exhaust gas of an internal combustion engine has a plurality of flow channels that can be flowed through along a main flow-through direction. The honeycomb body, especially a honeycomb body made of metal, is formed by a plurality of smooth and / or at least partially textured metal foils, and the metal foils are stacked on top of each other and wound and / or curled (wrapped up) into the final honeycomb body. The substrate formed by the metal foils is inserted into a housing for the purpose of stability and protection against mechanical interference and is durably connected to the housing.

[0003] In the simplest case, the housing is formed by a tube, which is designed to receive the substrate inside it. Another function of the housing is to ensure the flow-through of the honeycomb body and especially to avoid the exhaust gas flowing past the honeycomb body.

[0004] The fixation of the substrate in the housing must be achieved durably on the one hand, so usually a weld is formed between the substrate and the sleeve.

[0005] The disadvantages of the devices in the prior art lie especially in that the substrate mostly abuts against the sleeve comprehensively and is connected to the sleeve by welding, whereby the substrate cannot move flexibly radially and in the axial direction. In addition, a bridge that can conduct heat very well is formed by the substrate abutting against the sleeve comprehensively, whereby heat is conducted from the substrate to the sleeve and finally to the environment via the substrate. This results in a delayed reaching of the ignition temperature. Summary of the Invention

[0006] Therefore, the object of the present invention is to at least partially solve the problems described with reference to the prior art, and especially to implement a device for post-treatment of exhaust gas, which has improved thermal insulation between the substrate and the sleeve.

[0007] The object in terms of the device is achieved by a device having the features of claim 1. Advantageous improvements are given in the dependent claims. The features listed separately in the claims can be combined with each other and / or with the factual situation of the description arbitrarily. The description explains the present invention especially in combination with the drawings and gives additional implementation variants.

[0008] Helping with this is a device for the exhaust gas aftertreatment of an internal combustion engine, which device has a metallic substrate that can be flowed through along a main flow-through direction, and the substrate is inserted into a sleeve. The substrate is formed by (at least) one stacked layer, the stacked layer is formed by a plurality of metal foils, and the stacked layer is (rolled up) wound around at least one rolling point, either partially or completely. At least some of the metal foils are at least partially textured, whereby a plurality of flow channels are formed between the metal foils, and the flow channels can be flowed through along the main flow-through direction from the gas inlet side of the substrate towards the gas outlet side. In addition, an inner tube is arranged between the sleeve and the substrate, and an air gap is formed between the inner tube and the sleeve.

[0009] The substrate that is inserted into the inner tube and connected to the inner tube is arranged within the sleeve. An air gap that circumferentially surrounds is at least partially formed between the inner tube and the sleeve. The air gap forms a thermal insulation, thereby reducing the heat transfer from the substrate towards the (radially outer) sleeve.

[0010] The air gap is formed in particular such that the air gap radially spaces the inner tube apart from the sleeve. The air gap extends in particular at least 20%, preferably at least 40%, or particularly preferably more than at least 60% in the circumferential direction of the substrate or the inner tube. A plurality of air gaps that are axially spaced apart when necessary or extend in parallel can be formed.

[0011] The inner tube can have a significantly smaller material thickness compared to the sleeve and is mainly used to stabilize the substrate formed by a plurality of metal foils.

[0012] Particularly advantageously, the air gap is formed to (completely) surround the inner tube in the circumferential direction and extends at least along a section of the device in the axial direction. Preferably, the circumferentially surrounding air gap extends at least across a partition of the device in the axial direction. Advantageously, the air gap extends from the gas inlet side along the main flow-through direction towards the center of the device. The air gap preferably extends from the gas inlet side towards the center. Particularly high temperatures occur during operation especially in the region of the gas inlet side, so the heat transfer towards the sleeve should be reduced especially in this region.

[0013] The material thickness of the inner tube can be less than 1.0 mm [millimeter], preferably the material thickness is less than 0.6 mm, and particularly preferably the material thickness is less than 0.5 mm. The material thickness is preferably at least 0.3 mm.

[0014] It is proposed that the thickness of the air gap in the radial direction is greater than 1.0 mm [millimeter], preferably greater than 2.0 mm, particularly preferably greater than 3.0 mm and less than 5.0 mm. The thicker the air gap, the greater the insulating effect of the air gap. Preferably, the air gap is the largest especially in the following regions of the device, where the thermal load during operation in the exhaust device of the internal combustion engine is the highest or the greatest.

[0015] In an advantageous design, the air gap, or its thickness, can vary along the axial extension of the device, thereby forming an air gap of a suitable thickness for each foreseeable temperature level.

[0016] It can be stipulated that no air gap is formed in a defined region of the device, for example in the region on the gas outlet side.

[0017] The sleeve can have (at least partially) an insulating layer on its radially inward surface. The insulating layer is particularly advantageous for further reducing heat transfer. Preferably, the insulating layer has a lower thermal mass (compared to the sleeve). In a preferred embodiment, the insulating layer can be formed by a ceramic coating of the sleeve. Alternatively, the insulating layer can be formed by a plurality of thin metal foils, which are at least partially spaced apart from each other (by an insulating gas layer) by spacer pads.

[0018] The spacer pads can be formed, for example, by grooves and special shaping parts of the metal foil. For this purpose, the grooves have a thickness of, for example, a few tenths of a millimeter. Alternatively, the metal foil can have an additional textured structure, such as a corrugated structure, which forms an air cavity or an air layer between the individual metal foils and thus provides thermal insulation.

[0019] Furthermore, it can be expedient for the sleeve to have a cross-sectional constriction in the region of the gas inlet side, where the inner side of the sleeve abuts against the outer side of the inner tube. The cross-sectional constriction can be formed, for example, by a recess that is inserted into the sleeve from the outside. The recess is preferably formed in a conical shape (for example with a pointed end region), which means that the surface facing the inner tube is as small as possible. Thereby, the contact surface of the sleeve on the inner tube is reduced, which reduces the heat transfer from the inner tube to the sleeve. The reduction of the cross-section of the sleeve or the recess should prevent the coating carrier from entering the air gap or minimize it and / or prevent the hot exhaust gas from flowing into the air gap during the coating process of the device.

[0020] In an alternative design, instead of the recess, a circumferentially surrounding protrusion can also be provided, for example, on the inner surface. Description of the Drawings

[0021] The present invention and its scope will be described in detail below with reference to the schematic drawings according to embodiments. It should be noted that elements labeled with the same reference numerals in the drawings can have the same characteristics, unless otherwise explicitly stated herein. The elements illustrated in the drawings can be further characterized by the factual situation in other drawings and / or the description and / or the claims (and vice versa), unless explicitly excluded below. The figures show:

[0022] Figure 1 A cross-sectional view of the device is shown, in which a thermal insulation layer formed by a plurality of metal foils is arranged on the inner surface of the sleeve.

[0023] Figure 2 A cross-sectional view of the device is shown, in which a ceramic layer is arranged on the inner surface of the sleeve as a thermal insulation layer.

[0024] Figure 3 A cross-sectional view of the device is shown, in which the sleeve has a recess, and the sleeve abuts against the outer surface of the inner tube with the tip of the recess. And

[0025] Figure 4 A perspective view of a device for exhaust aftertreatment is shown, which device has a substrate in a sleeve. Detailed Description

[0026] Figure 1 A cross-section of the sleeve 1 is shown. The sleeve 1 has an insulating layer 2 on its inner surface. In Figure 1 the embodiment, the insulating layer 2 is formed by a plurality of metal foils 3 (of concentric or radially abutting layers), and the metal foils are stacked on top of each other. The metal foils 3 have (respectively surrounding) grooves 4, which space the metal foils 3 apart from each other. Overall, the metal foils 3 have a low thermal mass, so the metal foils are well suited to prohibit or at least reduce the heat transfer from the inside of the substrate 5 to the sleeve 1.

[0027] The metal foils 3 forming the insulating layer 2 can be substantially corresponding in terms of material, material thickness, etc. to the metal foils that (also) form the flow channels 13 or the stacked layers.

[0028] A substrate 5 is arranged in the center of the sleeve 1, and the substrate is received in an inner tube 6. An air gap 7 is formed between the inner tube 6 and the thermal insulation layer 2. The air gap 7 extends at least locally in the axial direction 8 over the entire device. Preferably, the air gap 7 is formed in the region of the gas inlet side and extends from there towards the center of the device.

[0029] The inner tube 6 has a significantly smaller thickness 9 compared to the sleeve 1.

[0030] Figure 2 A cross-sectional view of the device is shown, which device has a structure similar to the example in Figure 1 In contrast to Figure 1 , the thermal insulation layer 10 is formed by a ceramic coating. The remaining components are the same as those in the embodiment of Figure 1 .

[0031] Figure 3 A sleeve 11 with a groove 12 is shown, which groove is formed into the sleeve 11 from the outside. The groove 12 forms a tip towards the inside, which reaches the inner tube 6 and abuts against the inner tube. In addition, the sleeve 11 has a thermal insulation layer 10 as already shown in Figure 2 . Moreover, the other components are the same as those in the embodiments of Figure 1 and Figure 2 .

[0032] The recess 12 closes the air gap 7 so that when the base body 5 is coated with the metal foil, the coating carrier cannot enter the air gap 7 from the gas inlet side on one side and possibly block the air gap, and furthermore, the thermal exhaust cannot flow into the air gap 7 from the gas inlet side. The physical contact between the sleeve 11 and the inner tube 6 is kept as low as possible in order to keep the heat conduction as low as possible.

[0033] Figure 4 There is shown a device for exhaust aftertreatment, in particular for exhaust aftertreatment of an internal combustion engine, which device can be arranged in an exhaust path (shown in dashed lines) that can be flowed through by the exhaust gas. The device comprises a base body 5 which has a plurality of (parallel) flow channels 13 formed therein, which flow channels can be flowed through from a gas inlet side (front view) in a defined main flow direction (along the axial extension L) towards a gas outlet side (rear view not shown). The base body 5 comprises a plurality of (smooth and textured) metal foils 3 which are stacked on top of one another to form a stack layer and are wound around at least one winding point 14 (here wound in an S-shape around two winding points 14). The base body 5 has an axial extension L extending in the main flow-through direction 8 and a circumferential direction U extending transversely to the axial extension L. The base body 5 is surrounded on the outside by a sleeve 1, the special structure of which is known from the previous description of the other figures. Figures 1 to 3 The details of which are formed in particular on the gas inlet side of the device.

[0034] Figures 1 to 4 The embodiments of which are in particular not restrictive and are used to illustrate the inventive concept.

[0035] List of reference numerals:

[0036] 1 Sleeve

[0037] 2 Thermal insulation layer

[0038] 3 Metal foil

[0039] 4 Recess

[0040] 5 Base body

[0041] 6 Inner tube

[0042] 7 Air gap

[0043] 8 Axial direction

[0044] 9 Thickness

[0045] 10 Thermal insulation layer

[0046] 11 Sleeve

[0047] 12 Recess

[0048] 13 Flow channel

[0049] 14 rolling points

[0050] L axial extension

[0051] U circumferential direction

Claims

1. An apparatus for the exhaust gas aftertreatment of an internal combustion engine, the apparatus having a metallic substrate (5) which can be flowed through in a main flow direction, the substrate being inserted into a sleeve (1, 11), wherein, The substrate (5) is formed by stacked layers which are formed by a plurality of metal foils and are wound around at least one winding point. At least some of the metal foils are at least partially textured, whereby a plurality of flow channels are formed between the metal foils. The plurality of flow channels can be flowed through along a main flow-through direction from a gas inlet side of the substrate (5) towards a gas outlet side. It is characterized in that an inner tube (6) is arranged between the sleeve (1, 11) and the substrate (5), and an air gap (7) is formed between the inner tube (6) and the sleeve (1, 11).

2. The device according to claim 1, characterized in that, The air gap (7) is formed to surround the inner tube (6) in the circumferential direction and extends at least along a section of the device in the axial direction (8).

3. The device according to any one of the preceding claims, characterized in that, The air gap (7) extends from the gas inlet side towards the center of the device along the main flow-through direction.

4. The device according to any one of the preceding claims, characterized in that, The material thickness of the inner tube (6) is less than 1 mm, preferably less than 0.6 mm, and particularly preferably less than 0.5 mm.

5. The device according to any one of the preceding claims, characterized in that, The thickness of the air gap (7) in the radial direction is greater than 1 mm, preferably greater than 2 mm, and particularly preferably greater than 3 mm and less than 5 mm.

6. The device according to any one of the preceding claims, characterized in that, The sleeve (1, 11) has an insulating layer (2, 10) on its radially inward surface.

7. The device according to claim 6, characterized in that, The insulating layer (2, 10) has a lower thermal mass compared to the sleeve (1, 11).

8. The device according to any one of the preceding claims, characterized in that, The insulating layer (10) is formed by a ceramic coating of the sleeve (11).

9. The device according to any one of the preceding claims, characterized in that, The insulating layer (2) is formed by a plurality of thin metal foils (3) which are at least partially spaced apart from each other by spacer pads (4).

10. The device according to any one of the preceding claims, characterized in that, The sleeve (11) has a cross-sectional constriction (12) in the region of the gas inlet side, wherein the inner side of the sleeve (11) abuts against the outer side of the inner tube (6).

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