Exhaust aftertreatment system, exhaust silencer and method for manufacturing an exhaust aftertreatment system

Abstract

An exhaust aftertreatment device (26) comprises a housing (27) and a flow unit (31) arranged in the housing (27). The housing (27) comprises a first housing section (33) and a second housing section (34), as well as at least one inlet opening (29) and at least one outlet opening (30). All inlet openings (29) are arranged in the first housing section (33) and all outlet openings (30) in the second housing section (34). The first housing section (33) has a first contact surface (37) and the second housing section (34) has a second contact surface (38). The housing sections (32, 34) are in contact with each other via their contact surfaces. The flow unit (31) is clamped between a first clamping surface (35) on the first housing section (33) and a second clamping surface (36) on the second housing section (34) of the housing (27).The first contact surface (37) and the second contact surface (38) are parallel to each other in a displacement direction (32), forming a first angle (α) with the first clamping surface (35) and a second angle (β) with the second clamping surface (36). The first angle (α) and the second angle (β) are each greater than 0°. To manufacture the exhaust aftertreatment device (26), the two housing sections (33, 34) of the housing (27) are moved towards each other in the displacement direction (32) such that the distance (a, b) between the clamping surfaces (35, 36) decreases. In a subsequent process step, the housing sections (33, 34) are rigidly joined together.

Description

[0001] The invention relates to an exhaust aftertreatment device of the type specified in the preamble of claim 1, an exhaust silencer and a method for manufacturing an exhaust aftertreatment device.

[0002] From JP 2009-156158 A, an exhaust silencer with an exhaust aftertreatment system comprising a catalyst element is known. The housing of the exhaust aftertreatment system is formed by two interconnected housing parts. Claw sections can be provided on one of the housing parts to secure the catalyst element.

[0003] DE 10 2022 123 839 A1 and WO 2024 / 056 780 A1 disclose exhaust aftertreatment devices whose housings are formed from two partial shells which are sealed together at a circumferential edge.

[0004] Exhaust aftertreatment systems can be subjected to vibrations generated by the combustion engine during operation. It has been shown that the catalyst body can shrink due to temperature fluctuations within the exhaust aftertreatment system and engine vibrations, potentially leading to detachment. This can cause noise and damage.

[0005] The invention is based on the objective of creating an exhaust aftertreatment device of the generic type that has a simple design and a long service life. A further objective of the invention is to provide an exhaust silencer and a method for manufacturing an exhaust aftertreatment device.

[0006] This problem is solved with respect to the exhaust aftertreatment device by an exhaust aftertreatment device having the features of claim 1. With respect to the exhaust silencer, the problem is solved by an exhaust silencer having the features of claim 8. With respect to the method, the problem is solved by a method for manufacturing an exhaust aftertreatment device having the features of claim 9.

[0007] For the exhaust aftertreatment device, the flow unit is clamped between a first clamping surface and a second clamping surface of the housing. The first clamping surface is formed on the first housing section, and the second clamping surface is formed on the second housing section and, in particular, surrounds the at least one outlet opening. The first contact surface and the second contact surface are parallel to each other in a displacement direction that forms a first angle with the first clamping surface and a second angle with the second clamping surface, with both angles being greater than 0°.

[0008] The contact surfaces are therefore not parallel to the clamping surfaces. The contact surfaces are the surfaces where the housing sections are in contact with each other, i.e., where they abut each other. Because the contact surfaces are parallel to each other in the direction of movement, they can be moved relative to each other in this direction during the manufacturing of the exhaust aftertreatment system. The contact surfaces are designed so that they can be moved relative to each other in this direction before the housing sections are fixed in place. Due to the angle of more than 0° between the contact surfaces and the clamping surfaces, the clamping surfaces move towards or away from each other when the contact surfaces are moved parallel to each other.By shifting the contact surfaces relative to each other in the direction of movement, the distance between the clamping surfaces can be changed. This makes it possible to easily achieve a defined clamping of the flow unit between the clamping surfaces and / or defined external dimensions of the exhaust aftertreatment system by shifting the contact surfaces relative to each other during manufacturing.

[0009] Advantageously, the first clamping surface surrounds at least one inlet opening, in particular all inlet openings. Advantageously, the second clamping surface surrounds at least one outlet opening, in particular all outlet openings.

[0010] By surrounding the at least one inlet and at least one outlet opening with clamping surfaces, it can be easily ensured that the exhaust gases flow completely into the flow unit at the inlet and exit the flow unit at the outlet. Bypass flows that circumvent the flow unit at the inlet and / or outlet opening can be easily avoided.

[0011] Advantageously, the first and second angles each measure at least 20°, and particularly at least 30°. It is especially preferred that the first and second angles are perpendicular to the direction of displacement. This allows the contact surfaces to be displaced relative to each other perpendicular to the clamping surfaces. As a result, the distance traveled by the clamping surfaces relative to each other corresponds to the change in the distance between the clamping surfaces.

[0012] Advantageously, the exhaust aftertreatment device is designed such that each partial flow of an exhaust gas stream passing through the aftertreatment device travels a path within the flow unit that corresponds to at least 50% of the minimum thickness of the flow unit between the at least one inlet opening and the at least one outlet opening. The minimum thickness corresponds to the smallest distance between the at least one inlet opening and the at least one outlet opening. This ensures sufficient conversion of the exhaust gas stream passing through the aftertreatment device.

[0013] Advantageously, the housing sections are firmly connected to one another. The alignment of the clamping surfaces and the contact surfaces at the first and second angles relative to each other is advantageously intended solely for creating a defined clamping of the flow unit during the manufacture of the exhaust aftertreatment system. Displacement of the contact surfaces relative to each other during operation of the exhaust aftertreatment system is advantageously not provided for.

[0014] In a particularly preferred embodiment, the flow unit is formed by at least one wire body. It is possible for the flow unit to be formed by several wire bodies. It is possible for the flow unit to have at least one section coated with a catalytically active coating. Alternatively or additionally, it is possible for the flow unit to have at least one section coated with a washcoat. It is possible for the flow unit to have at least two sections with different amounts of catalytic coating relative to the volume of the sections. The section with a larger amount of catalytically active coating relative to its volume may be arranged upstream of a section with a smaller amount of catalytically active coating relative to its volume.However, it can also be advantageous for a sub-section with a smaller amount of catalytically active coating relative to its volume to be arranged upstream of a sub-section with a larger amount of catalytically active coating relative to its volume. It can be provided that, if the flow unit has at least two sub-sections, at least one of the sub-sections is arranged entirely within one of the housing sections. Preferably, a sub-section having a coating, in particular a catalytically active coating, is arranged entirely within one housing section.

[0015] If the flow unit has several sections, it is particularly preferred that each section of the flow unit is formed by at least one wire body. The wire bodies are advantageously uniform, either uncoated or coated. The coating is, in particular, a washcoat and / or a catalytically active coating. This allows for simple production of the coating, for example, by dipping.

[0016] Advantageously, the at least one inlet opening and / or the at least one outlet opening are surrounded by a centering surface. The flow unit advantageously rests against the centering surface. The centering surface is advantageously inclined at an angle of at least 10°, and particularly at least 20°, to the direction of movement. Because the centering surface is inclined at an angle to the direction of movement, the centering surface aligns the flow unit with the centering surface when the housing sections move towards each other in the direction of movement. This ensures, in particular, a minimal path that a partial flow of exhaust gas must travel through the flow unit before, for example, a cavity formed on the outer circumference of the flow unit can be reached.

[0017] In a preferred embodiment, the centering surface is a truncated cone surface. The contact surfaces are advantageously cylindrical. This is particularly advantageous when the housing of the exhaust aftertreatment unit has an approximately cylindrical shape.

[0018] In an advantageous alternative embodiment, the housing may be formed by at least six mutually opposing sides. For example, the housing may be approximately cuboid in shape. The plane in which the contact surfaces lie may particularly preferably extend through two opposite sides of the housing, especially bisecting them approximately in the middle. Particularly preferably, the contact surfaces extend through two opposite edges of the housing. The edges of the housing may also be rounded.

[0019] An exhaust silencer is designed to have an exhaust inlet, an exhaust outlet and an exhaust aftertreatment device arranged in the flow path between the exhaust inlet and the exhaust outlet.

[0020] Advantageously, the exhaust silencer comprises a first silencer chamber, a second silencer chamber, and a partition separating the first and second silencer chambers. In a preferred embodiment, a housing section of the exhaust aftertreatment system is formed integrally with the partition. The housing section is thus formed integrally with the partition. Preferably, the partition and the housing section are formed from a sheet metal piece that extends outside the plane of the partition in the area of ​​the housing section and has openings in this area.

[0021] A method for manufacturing an exhaust aftertreatment device involves moving the two housing sections towards each other in the displacement direction such that the distance between the clamping surfaces decreases, and then firmly joining the housing sections together in a subsequent process step. By moving the housing sections towards each other during the manufacturing of the exhaust aftertreatment device in such a way as to reduce the distance between the clamping surfaces, a predetermined desired clamping of the flow unit can be achieved. The connection of the housing sections can be accomplished, for example, by a welding process, in particular by spot welding, projection welding, MIG / MAG welding, or laser welding. Other methods of joining the housing sections are also possible.Preferably, the housing sections are connected to each other in such a way that they cannot be separated from each other without destruction.

[0022] Advantageously, the movement of the housing sections towards each other is controlled. The housing sections are advantageously moved towards each other until a predetermined distance between the clamping surfaces is reached. This is particularly advantageous when the exhaust aftertreatment system, in its finished state, is to have a predetermined dimension, for example, to maintain a predetermined flow length or a predetermined path between the at least one inlet opening and the at least one outlet opening. An alternative method allows the housing sections to be moved towards each other by force. For this purpose, the housing sections are advantageously moved towards each other until a predetermined force for the displacement is achieved. This allows clamping with a predetermined force or preload to be set.This is particularly advantageous when the flow unit has large dimensional tolerances before being installed in the housing. The force-controlled displacement of the housing sections relative to each other ensures a secure clamping fit between the housing sections, even with large dimensional tolerances in the flow unit.

[0023] Exemplary embodiments of the invention are explained below with reference to the drawing. The drawing shows: Fig. 1 a schematic sectional view of a chainsaw, Fig. 2 a perspective view of the exhaust aftertreatment system of the exhaust silencer of the chainsaw Fig. 1, Fig. 3 a side view of the exhaust aftertreatment system Fig. 2, Fig. 4 a perspective exploded view of the exhaust aftertreatment system Fig. 2, Fig. 5 an exploded view of the exhaust aftertreatment system in side view, Fig. 6 an enlarged cross-sectional view through the exhaust aftertreatment system Fig. 2, Fig. 7 a partial representation of a wire body of the flow unit, Fig. 8 and Fig. 9 perspective sectional views of the exhaust aftertreatment system in different states during manufacturing, Fig. 10 a side view of an embodiment of an exhaust aftertreatment device, Fig. 11 a perspective sectional view through the exhaust aftertreatment system from Fig. 10, Fig. 12 a perspective view of the exhaust aftertreatment system from Fig. 10, Fig. 13 to Fig. 15 perspective views of an exhaust gas aftertreatment system outlet bowl Fig. 10.

[0024] Fig. Figure 1 shows a chainsaw 1 as an exemplary embodiment of a hand-held, preferably hand-carried, work tool. The present invention can also be used with other hand-held, preferably hand-carried work tools, such as angle grinders, brush cutters, or blowers. Use with ground-guided work tools, such as lawnmowers, is also possible.

[0025] The chainsaw 1 has a housing 2 on which a rear handle 3 is arranged for guiding and carrying the chainsaw 1 during operation. Operating elements, in this exemplary embodiment a throttle lever 4 and a throttle lock 5, are arranged on the rear handle 3. The chainsaw 1 has a guide bar 6 on which a saw chain 7 is arranged. During operation, the saw chain 7 is driven around the guide bar 6 by a drive motor 8 located in the housing 2. The drive motor 8 is advantageously a single-cylinder engine. The drive motor 8 is particularly a two-stroke engine.

[0026] The term "equipment housing" is to be understood broadly in this context and refers to a structure that can hold elements of the chainsaw 1 and at least partially enclose it from the environment. The equipment housing 2 can be open to the environment and can be made up of multiple parts. Preferably, the equipment housing 2 comprises several sections arranged to be movable relative to one another and connected to each other via vibration elements.

[0027] The drive motor 8 has a cylinder 12 in which a combustion chamber 14 is formed. The combustion chamber 14 is bounded by a piston 13 which is driven reciprocatingly within the cylinder 12. The piston 13 drives a crankshaft 17, which is rotatably mounted about an axis of rotation 18 in a crankcase 15, via a connecting rod 16. The piston 13 controls the connection of the intake port 11 with the interior of the crankcase 15. The piston 13 also controls an exhaust port 21 leading from the combustion chamber 14. The interior of the crankcase 15 is connected to the combustion chamber 14 via at least one transfer port 19 in at least one position of the piston 13, preferably when the piston 13 is in the region of bottom dead center. A spark plug 20 projects into the combustion chamber 14.

[0028] The drive motor 8 includes an air filter 9 through which air is drawn in during operation. In the exemplary embodiment, a fuel supply device 10 is provided for supplying fuel. During operation, the drive motor 8 draws air through the air filter 9 and an intake duct 11 into the crankcase 15. A section of the intake duct 11 is formed in the fuel supply device 10, for example, a carburetor. Other designs of the fuel supply device 10, for example, as a fuel valve, are also possible. Alternative arrangements of the fuel supply device 10 may also be advantageous. The fuel supply device 10 can supply the fuel into the intake duct 11, into the interior of the crankcase 15, into a transfer port 19, and / or a combustion chamber 14 of the drive motor 8.

[0029] During operation of the drive motor 8, as the piston 13 rises, fuel / air mixture is drawn into the crankcase 15 via the intake port 11 in this embodiment. During the piston's downward stroke, the fuel / air mixture in the crankcase 15 is compressed. As soon as the transfer ports 19 from the piston 13 to the combustion chamber 14 open, fuel / air mixture flows into the combustion chamber 14. During the subsequent upward stroke of the piston 13, the fuel / air mixture in the combustion chamber 14 is compressed and ignited by the spark plug 20 near the piston's top dead center. The resulting combustion accelerates the piston 13 towards the crankcase 15. The exhaust port 21 leads into an exhaust port 22, which connects to an exhaust silencer 23. The exhaust silencer 23 is fixed to the cylinder 12. As soon as the exhaust port 21 is opened by the piston 13, exhaust gases can flow into the exhaust silencer 23 via the exhaust channel 22.

[0030] The exhaust silencer 23 has an exhaust inlet 24, which in the exemplary embodiment leads into a first silencer chamber 48. It is possible to arrange further silencer chambers between the exhaust inlet 24 and the first silencer chamber 48. The first silencer chamber 48 is separated from a second silencer chamber 49 by a partition 28. The exhaust silencer 23 includes an exhaust aftertreatment unit 26. In the exemplary embodiment, the exhaust aftertreatment unit 26 is arranged in the partition 28. The exhaust aftertreatment unit 26 comprises a housing 27 in which a flow-through unit 31 is arranged. In the exemplary embodiment, the exhaust gases flow from the first silencer chamber 48 through the exhaust aftertreatment unit 26 into the second silencer chamber 49. The exhaust gases flow through the flow-through unit 31.

[0031] An exhaust outlet 25 leads from the exhaust silencer 23. The exhaust outlet 25 can lead from the second silencer chamber 49. However, it can also be provided that further silencer chambers are arranged in the direction of flow between the second silencer chamber 49 and the exhaust outlet 25.

[0032] The Fig. 2, Fig. 3, Fig. 4, Fig. 5 to Fig. Figure 6 shows the design of the exhaust aftertreatment system 26 in detail. How Fig. As shown in Figure 2, the housing 27 of the exhaust aftertreatment device 26 has a plurality of outlet openings 30. Exhaust gases can flow out of the housing 27 through the outlet openings 30. A single outlet opening 30 can also be advantageous. In the exemplary embodiment, the housing 27 of the exhaust aftertreatment device 26 is approximately cylindrical, and the outlet openings 30 are arranged on a flat end face of the housing 27. The outlet openings 30 are arranged evenly distributed in a circular area of ​​the housing 27, as shown. Fig. Figure 2 shows the exhaust aftertreatment device 26 having a central axis 51. The central axis 51 forms the axis of symmetry of the cylindrical housing 27. The circular area is arranged concentrically around the central axis 51 of the exhaust aftertreatment device 26.

[0033] How Fig. Figure 3 shows that the housing 27 is composed of a first housing section 33 and a second housing section 34. In the exemplary embodiment, the first housing section 33 is formed in multiple parts. The second housing section 34 is formed in one piece in the exemplary embodiment. A one-piece design of the first housing section 33 and / or a multi-part design of the second housing section 34 can also be advantageous. During the manufacture of the exhaust aftertreatment device 26, the housing sections 33 and 34 are movable relative to each other, at least temporarily, in a displacement direction 32, as will be described in more detail below.

[0034] In the exemplary embodiment, the first housing section 33 comprises an inlet shell 39, which is formed integrally with the partition 28. Alternatively, the inlet shell 39 can be formed separately from the partition 28 and fixed to the partition 28. How Fig. As shown in Figure 4, the inlet shell 39 comprises a plurality of inlet openings 29. The inlet openings 29 are arranged in a circular area concentric to the central axis 51, corresponding to the outlet openings 30.

[0035] In the exemplary embodiment, the first housing section 33 comprises an intermediate ring 41, which is fixed to the partition 28. For this purpose, the intermediate ring 41 has a flange 50 extending perpendicular to the central axis 51. The flange 50 is positioned as Fig. 3 indicates the location on the partition wall 28 and can be fixed to the partition wall 28, for example by welding.

[0036] In the exemplary embodiment, the second housing section 34 is formed by an outflow dish 40. The outflow dish 40 overlaps the intermediate ring 41, as Fig. 3 shows.

[0037] How the perspective exploded view in Fig. Figure 4 shows that a flow-through unit 31 is arranged in the housing 27 of the exhaust aftertreatment device 26. In the exemplary embodiment, the flow-through unit 31 is multi-part, namely two-part. A one-piece or multi-part design of the flow-through unit 31 can also be advantageous. The flow-through unit 31 is advantageously made of compressible material that is essentially dimensionally stable during operation. Advantageously, the flow-through unit 31 is made of wire. In the exemplary embodiment, the flow-through unit 31 has a first wire body 42 and a second wire body 43, as also shown. Fig. 5 shows. In Fig. Figure 4 shows a clamping surface 35 formed on the inlet shell 39, against which the flow unit 31 rests. The inlet openings 29 are arranged in the clamping surface 35. All inlet openings 29 are completely surrounded by areas of the clamping surface 35.

[0038] The outlet bowl 40 has a clamping surface 36 that completely surrounds all outlet openings 30 and which is located in the Fig. 6 and Fig. 8 is visible.

[0039] How Fig. As shown in Figure 5, the inlet shell 39 has a base 52, a conical section 53 adjoining the base 52 circumferentially, and a cylindrical section 54 adjoining the conical section 53. In the exemplary embodiment, the base 52 is perpendicular to the central axis 51. The base 52 has the inlet openings 29. The conical section 53 and the cylindrical section 54 are rotationally symmetrical about the central axis 51.

[0040] The intermediate ring 41 has a cylindrical section 58 which is rotationally symmetrical about the central axis 51. In the exemplary embodiment, the flange 50 connects to the cylindrical section 58. The cylindrical section 58 of the intermediate flange 41 has an outer diameter i.

[0041] The flow unit 31 is essentially cylindrical and has a diameter g. The flow unit 31 has an inlet area 60, which in the exemplary embodiment is designed to contact the clamping surface 35 and the inlet openings 29. With respect to a main flow direction 59 through the exhaust aftertreatment device 26, the inlet area 60 forms the upstream side of the flow unit 31. With respect to the main flow direction 59, the flow unit 31 has an outlet area 61 on its downstream side. The outlet area 61 is designed to contact the second clamping surface 36 and the outlet openings 30, as shown. Fig. Figure 6 shows that the main flow direction 59 is directed from the inlet openings 29 to the outlet openings 30 and denotes the flow direction through the housing 27 that would result if no flow unit 31 were arranged in the housing 27. Due to the irregular shape of the openings in the flow unit 31, which are formed between the individual wire loops, the exhaust gases also flow in directions other than the main flow direction 59. Fig. Figure 5 shows that the flow unit 31 has a chamfer 62 adjacent to the inlet surface 60 and a chamfer 63 adjacent to the outlet surface 61.

[0042] The outflow bowl 40 comprises a base 55, which is oriented perpendicular to the central axis 51. A conical section 56 adjoins the base 55, and a cylindrical section 57 adjoins the conical section 56.

[0043] How Fig. Figure 6 shows that the cylinder section 57 has an inner diameter h. The inner diameter h is, as Fig. Figure 6 shows that the outer diameter i of the intermediate flange 41 is larger. This allows the second housing section 34 to overlap the first housing section 33 at the intermediate flange 41, as shown in the sectional view in Figure 6. Fig. 6 shows.

[0044] The intermediate ring 41 has an inner diameter e at its cylindrical section 58. The cylindrical section 54 of the inlet shell 39 has an inner diameter f. In the exemplary embodiment, the inner diameter e of the cylindrical section 58 of the intermediate ring 41 corresponds to the inner diameter f of the cylindrical section 54 of the inlet shell 39. The inner diameters e and f are larger than the outer diameter g of the flow unit 31, so that a free space 71 is formed adjacent to an outer circumference 65 of the flow unit 31.

[0045] The conical sections 53 and 56 of inlet shell 39 and outlet shell 40 form centering surfaces 44 and 45, respectively, on their inner sides. The central axis 51 lies parallel to a displacement direction 32, which in Fig. Figure 6 is shown. The centering surface 44 on the inlet shell 39 is inclined at an angle γ to the direction of displacement 32. The centering surface 45 on the outlet shell 40 is inclined at an angle δ to the direction of displacement 32. The angle γ and the angle δ are advantageously at least 10°, and particularly at least 20°.

[0046] Housing sections 33 and 34 ( Fig. 5) The housing sections 33 and 34 are in contact with each other at the intermediate ring 41 and the cylindrical section 57 of the outlet shell 40. The housing sections 33 and 34 can be in direct contact with each other. Alternatively, the housing sections 33 and 34 can be in contact with each other via a connecting element, for example, hardened molten metal from a weld, solder, or adhesive. The intermediate ring 41 forms a first contact surface 37 on its outer circumference. The outlet shell 40 forms a second contact surface 38 on the inner circumference of its cylindrical section 57. The housing sections 33 and 34 are in contact at the contact surfaces 37 and 38 ( Fig. 5) are in contact with each other. In the exemplary embodiment, the contact surfaces 37 and 38 are cylindrical and rotationally symmetrical about the central axis 51. In the displacement direction 32, which runs parallel to the central axis 51, the contact surfaces 37 and 38 are parallel to each other. This allows the housing sections 33 and 34 to be displaced relative to each other in the displacement direction 32, as will be explained in more detail below.

[0047] The flow unit 31 is clamped in the housing 27 between the clamping surfaces 35 and 36. The preload under which the flow unit 31 is installed is advantageously chosen to be large enough that the flow unit 31 remains fixed in the housing 27 between the clamping surfaces 35 and 36 even under the temperature development and vibrations during operation and cannot loosen.

[0048] In the exemplary embodiment, the first clamping surface 35 is perpendicular to the direction of displacement 32. The first clamping surface 35 forms an angle α of 90° with the direction of displacement 32. The second clamping surface 36 forms an angle β with the direction of displacement 32, which is also greater than 0°. In the exemplary embodiment, the angle β is also 90°. The first angle α and the second angle β are advantageously at least 20°, and particularly at least 30°.

[0049] The flow unit 31 has a minimum thickness d, measured from the upstream end face 60 to the downstream end face 61, in a region of the flow unit 31 adjacent to the inlet openings 29 and outlet openings 30. In the exemplary embodiment, the end faces 60 and 61 are flat and parallel to each other, so that the thickness d of the flow unit is constant in this region. For a flow unit 31 in which the end faces 60 and 61 are not flat and / or constant, the thickness is the minimum thickness in this region. The flow unit 31 can have a smaller thickness outside of regions adjacent to the inlet openings and outlet openings 30. The minimum thickness d corresponds to the shortest path that exhaust gases can travel through the flow unit 31 from an inlet opening 29 to an outlet opening 30.The shortest path lies entirely within flow unit 31.

[0050] The clamping surfaces 35 and 36 are arranged and designed such that each partial flow of an exhaust gas flow passing through the exhaust gas aftertreatment device 26 travels a path in the flow unit 31 that corresponds to at least 50% of the smallest thickness d of the flow unit 31 between the inlet opening 29 and the outlet opening 30. In the exemplary embodiment, the exhaust gas flow can be Fig. The exhaust gas flows into an external inlet opening 29 and from there into the free space 71 formed between the flow unit 31 and the housing 26, thus forming a bypass flow to a section of the flow unit 31. From the free space 71, the exhaust gas can then flow back through the flow unit 31 to an external outlet opening 30. In the exemplary embodiment, the inlet openings 29 and the outlet openings 30 are spaced a distance k from the outer circumference 65 of the flow unit 31. The distance k of the inlet opening 29 and the outlet opening 30 to the outer circumference 65 of the flow unit 31 is selected such that the exhaust gas flow in the flow unit 31 must travel a path that corresponds to at least 50% of the smallest thickness d. The distance k is advantageously at least one quarter of the thickness d. This ensures sufficient conversion of the exhaust gas flow in the flow unit 31.

[0051] Fig. Figure 7 shows an exemplary and partial view of the wire body 42. The wire body 42 can, for example, be made of knitted and pressed wire 64. The wire body 43 can be designed accordingly. Alternatively or additionally, at least one wire body 42, 43 of the flow unit 31 can be formed by individual pieces of wire or the like. The flow unit 31 is considered here to be the imaginary outer body that tightly encloses the at least one wire body 42, 43. The wire bodies 42 and 43 each comprise the wire 64 as well as openings 72 formed between the wire loops, through which exhaust gases can flow through the wire bodies 42 and 43. All dimensions of the flow unit 31 refer to this outer body. In the figures, with the exception of Fig. 7 - for the wire bodies 42 and 43, the outer body of the wire bodies 42 and 43 is shown.

[0052] The wire bodies 42 and / or 43 can be uncoated. Alternatively, at least one wire body 42 and / or 43 can have a washcoat coating. A washcoat is a coating that increases the surface area, in particular the wire surface area, without lowering the activation energy for the chemical reaction of the exhaust gas or certain exhaust gas components. Additionally or alternatively, at least one wire body 42, 43 of the flow unit 31 can be at least partially, preferably completely, coated with a catalytic coating. A catalytic coating is a coating that lowers the activation energy for the chemical reaction. In particular, a catalytic coating is a coating containing a precious metal. A washcoat coating can be provided as a primer beneath a catalytic coating. It is particularly preferred that the flow unit 31 has only a partial catalytic coating.This allows the manufacturing costs of the flow-through unit to be kept comparatively low. It is possible for both wire bodies 42 and 43 to have the same coating, or for both wire bodies to be uncoated. Alternatively, it is possible for the wire bodies 42 and 43 to have different coatings. For example, it is possible for only one of the wire bodies 42 or 43 to have a catalytic coating and / or for only one of the wire bodies 42 or 43 to have a washcoat coating. A combination with other wire bodies or other units through which exhaust gas can flow can also be advantageous.

[0053] The Fig. 8 and Fig. Figure 9 shows the exhaust aftertreatment device 26 during its manufacture. Fig. Figure 8 shows the exhaust aftertreatment device 26 in a process step in which the flow unit 31 is positioned between the housing sections 33 and 34. In this position, the clamping surfaces 35 and 36 are spaced a distance a from each other. The distance a is significantly greater than the thickness c of the flow unit 31. Both the distance a and the thickness c are measured parallel to the central axis 51. The thickness c is measured from the inlet surface 60 to the outlet surface 61.

[0054] To clamp the flow unit 31 between the clamping surfaces 35 and 36, the housing sections 33 and 34 are moved towards each other in the displacement direction 32 such that the distance a between the clamping surfaces 35 and 36 decreases. It may be provided that the housing sections 33 and 34 are moved towards each other by a distance s which is defined in Fig. Figure 8 is shown schematically. The path s is advantageously slightly larger than the difference between the distance a and the initial thickness c of the flow unit 31. This compresses the flow unit 31 between the clamping surfaces 35 and 36 and clamps it firmly between them. The chamfers 62 and 63 of the flow unit 31 come into contact with the centering surfaces 44 and 45 of the housing 27 when the housing sections 33 and 34 are moved towards each other. Due to the contact of the chamfers 62 and 63 with the centering surfaces 44 and 45, the flow unit 31 is centered on the central axis 51.

[0055] It may be provided that the flow unit 31, as in Fig. Figure 6 shows that the flow unit 31 has a small distance on its outer circumference from the housing 27 of the exhaust aftertreatment device 26. However, it can also be provided that the flow unit 31 rests against the housing 27 on its outer circumference, as shown in the Fig. 8 and Fig. 9 shown.

[0056] After the housing sections 33 and 34 are moved towards each other in the direction of displacement 32, the clamping surfaces 35 and 36 have a distance b. The distance b corresponds at least to the initial thickness c of the flow unit 31. Preferably, the distance b is smaller than the initial thickness c.

[0057] Because the clamping surfaces 35 and 36 enclose angles α and β of 90° with the displacement direction 32, clamping of the flow unit 31 between the clamping surfaces 35 and 36 can be achieved during manufacturing even with small displacements of the housing sections 33 and 34 relative to each other in the displacement direction 32. The first angle α and the second angle β are advantageously at least 20°, and particularly at least 30°. Even with smaller angles α and β, a change in the distance a between the clamping surfaces 35 and 36 can be achieved by displacing the housing sections 33 and 34 relative to each other.

[0058] It can be provided that the housing sections 33 and 34 are moved towards each other until a predetermined distance b between the clamping surfaces 35 and 36 is reached. Alternatively, it can be provided that the housing sections 33 and 34 are moved towards each other until a predetermined force for displacement is reached. In the figures, the displacement direction 32 is shown as the displacement of the second housing section 34 relative to the first housing section 33. Only the relative movement of the housing sections 33 and 34 is relevant, and not which housing section 33 and / or 34 actually moves.

[0059] In the exemplary embodiment according to Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8 to Fig. The centering surfaces 44 and 45 are frustoconical surfaces. After the housing sections 33 and 34 have been moved, they are permanently joined together, for example by welded connections. During operation, no further movement of the housing sections relative to each other in the displacement direction 32 is possible.

[0060] In the exemplary embodiment according to the Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8 to Fig. 9 the first housing section 33 includes an area of ​​the partition 28. Alternatively, the first housing section 33 can be movable relative to the partition 28 during manufacturing and the second housing section 34 can include an area of ​​the partition 28.

[0061] The Fig. 10, Fig. 11, Fig. 12, Fig. 13, Fig. 14 to Fig. Figure 15 shows a further embodiment of an exhaust aftertreatment device 26. The same reference numerals denote corresponding elements in all figures. The exhaust aftertreatment device 26 of the second embodiment has an approximately cuboid housing 27. The housing 27 is formed by six pairs of opposing sides 46, 66, 67. Specifically, there are two opposing sides 46, two opposing sides 66, and two opposing sides 67. This results in an approximately cuboid shape for the housing 26. The edges where sides 66 and 67 meet are formed by relatively wide chamfers.

[0062] How Fig. As shown in Figure 10, the housing 27 comprises a first housing section 33 and a second housing section 34. As the Fig. 10 and Fig. As shown in Figure 11, the sides 46 of the housing 27 are each formed halfway on the first housing section 33 and halfway on the second housing section 34. The first housing section 33 is integrally formed with the partition 28 and encompasses a portion of the partition 28. The first housing section 33 forms an inlet shell 39. The second housing section 34 has a rim 73 with which the housing section 34 is fixed to the partition 28. The rim 73 runs parallel to the partition 28 and rests against it. The second housing section 34 forms an outlet shell 40. In the exemplary embodiment, the first housing section 33 and the second housing section 34 are each formed in one piece. A multi-part design of one or both housing sections 33, 34 can also be advantageous.

[0063] The first housing section 33 has a contact surface 37 formed on the partition 28. The second housing section 34 has a contact surface 38 formed on the edge 73 in the exemplary embodiment. The housing sections 33 and 34 are in contact with each other at the contact surfaces 37 and 38 and can be displaced relative to each other in a displacement direction 32 that runs parallel to the partition 28. The contact surfaces 37 and 38 lie in a plane 68 that divides the opposite sides 46 of the housing 27. The plane 68 in which the contact surfaces 37 and 38 lie extends through opposite edges 47 of the housing 27.

[0064] The sides 66 of the housing 27 form clamping surfaces 35 and 36 on their inner sides, as Fig. Figure 11 shows that a flow unit 31 is clamped between the clamping surfaces 35 and 36. If the second housing section 34 is moved in the displacement direction 32 relative to the first housing section 33, so that the contact surfaces 37 and 38 ( Fig. 10) as they slide against each other, the distance between the contact surfaces 35 and 36 decreases to a desired dimension or until a desired force for displacement is reached. In Fig. Figure 11 shows the distance b after the displacement and fixing of the housing sections 33 and 34 to each other.

[0065] How Fig. As shown in Figure 11, the first contact surface 35 forms an angle α greater than 0° with the displacement direction 32. The angle α is greater than 20°, and preferably greater than 30°. In the exemplary embodiment, the angle α is 45°. The second contact surface 36 forms an angle β greater than 0°, and preferably greater than 20°, with the displacement direction 32 and the plane 68. In the exemplary embodiment, the angle β is 45°. Particularly preferably, the angles α and β are equal, resulting in uniform clamping of the flow unit 31.

[0066] As the Fig. 12, Fig. 13 to Fig. As shown in Figure 14, the second housing section 34 has a plurality of outlet openings 30. The outlet openings 30 are formed on both side 66 and side 67 of the second housing section 34. The first housing section 33 has inlet openings 29. The inlet openings 29 are provided on sides 66 and 65 of the inlet shell 39 and are arranged and designed in a manner corresponding to the outlet openings 30. The inlet openings 29 are advantageously oriented with respect to plane 68 ( Fig. 11) arranged and designed in a mirror-symmetrical manner to the exit openings 40.

[0067] How Fig. Figure 12 shows that the partition 28 has guides 69 on which the outlet dish 40 is mounted. The outlet dish 40 has receptacles 70 for this purpose. The guides 69 and the receptacles 70 run parallel to the direction of movement 32.

[0068] The in the Fig. 10, Fig. 11, Fig. 12, Fig. 13, Fig. 14 to Fig. The exhaust aftertreatment device 21 shown in Figure 15 can be manufactured by moving the housing sections 33 and 34 relative to each other in the displacement direction 32 such that the distance b between the clamping surfaces 35 and 36 decreases until a desired distance b is reached or until a desired force for displacement is achieved. Subsequently, the housing sections 33 and 34 are firmly connected to each other, for example by welding the edge 73 to the partition 28. This allows a desired clamping and preload of the flow unit 31 between the clamping surfaces 35 and 36 to be achieved easily.

[0069] Further advantageous embodiments can result from any combination of the elements of the exemplary embodiments.

Claims

[1] Exhaust aftertreatment device (26) with a housing (27) and a flow unit (31) arranged in the housing (27), wherein the housing (27) comprises a first housing section (33) and a second housing section (34), wherein the housing (27) has at least one inlet opening (29) and at least one outlet opening (30), wherein all inlet openings (29) are arranged in the first housing section (33) and all outlet openings (30) are arranged in the second housing section (34), wherein the first housing section (33) has a first contact surface (37) and the second housing section (34) has a second contact surface (38), wherein the housing sections (33, 34) are in contact with each other via their contact surfaces (37, 38), characterized by, that the flow unit (31) is held clamped between a first clamping surface (35) and a second clamping surface (36) of the housing (27), wherein the first clamping surface (35) is formed on the first housing section (33) and wherein the second clamping surface (36) is formed on the second housing section (34), and that the first contact surface (37) and the second contact surface (38) run parallel to each other in the displacement direction (32), forming a first angle (α) with the first clamping surface (35) and a second angle (β) with the second clamping surface (36), wherein the first angle (α) and the second angle (β) are each greater than 0°. [2] Exhaust aftertreatment device (26) according to claim 1, characterized by that the first angle (α) and the second angle (β) are at least 20°. [3] Exhaust aftertreatment device (26) according to claim 1 or 2, characterized by, that the clamping surfaces (35, 36) are arranged and designed such that each partial flow of an exhaust gas flow passing through the exhaust aftertreatment device (26) travels a path in the flow unit (31) that corresponds to at least 50% of the smallest thickness (d) of the flow unit (31) between the at least one inlet opening (29) and the at least one outlet opening (30). [4] Exhaust aftertreatment device (26) according to one of claims 1 to 3, characterized by , that the housing sections (33, 34) are firmly connected to each other. [5] Exhaust aftertreatment device (26) according to one of claims 1 to 4, characterized by , that the flow unit (31) is formed by at least one wire body (42, 43). [6] Exhaust aftertreatment device (26) according to one of claims 1 to 5, characterized by, that the at least one inlet opening (29) and / or the at least one outlet opening (30) is surrounded by a centering surface (44, 45) against which the flow unit (31) rests and which is inclined to the displacement direction (32) by an angle (γ, δ) of at least 10°. [7] Exhaust aftertreatment device (26) according to one of claims 1 to 6, characterized by , that the housing (27) is formed by at least six pairwise opposite sides (46) and a plane (68) in which the contact surfaces (37, 38) lie runs through two opposite sides (46) of the housing (27). [8] Exhaust silencer (23) with an exhaust inlet (24), an exhaust outlet (25) and an exhaust aftertreatment device (26) arranged in the flow path between the exhaust inlet (24) and the exhaust outlet (25) according to one of claims 1 to 7. [9] Method for manufacturing an exhaust aftertreatment device (26) according to any one of claims 1 to 7, characterized by , that the two housing sections (33, 34) of the housing (27) are moved towards each other in the displacement direction (32) such that the distance (a, b) between the clamping surfaces (35, 36) is reduced, and the housing sections (33, 34) are firmly connected to each other in a subsequent process step. [10] Method according to claim 9, characterized by , that the housing sections (33, 34) are moved towards each other until a predetermined distance (b) between the clamping surfaces (35, 36) is reached. [11] Method according to claim 9, characterized by , that the housing sections (33, 34) are moved towards each other until a predetermined force for displacement is achieved.

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