Exhaust gas aftertreatment device, exhaust gas silencer and method for producing an exhaust gas aftertreatment device

Abstract

The invention relates to an exhaust gas aftertreatment device, wherein the exhaust gas aftertreatment device (A32) comprises a throughflow unit (A33), which is held in a housing (A34) of the exhaust gas aftertreatment device (A32), wherein the throughflow unit (A33) comprises at least one wire body (A36, A40), wherein the wire body (A36, A40) has at least one first region (A37, A41) having a first mean density and at least one second region (A38, A42) having a second mean density, the second mean density being at least 1.5 times the first mean density, and wherein the wire body (A36, A40) is held in a clamped manner on the second region (A38, A42) between at least two clamping portions (A46, A47) of the housing (A34).

Description

[0001] A 1-98002 / sta

[0002] (PA21548WO)

[0003] 1

[0004] Exhaust aftertreatment system, exhaust silencer and method for manufacturing an exhaust aftertreatment system

[0005] The invention relates to an exhaust aftertreatment device of the type specified in the preamble of claim 1 and to a method for manufacturing an exhaust aftertreatment device.

[0006] From JP 2017-217641 A, an exhaust aftertreatment device is known which comprises a flow unit made of a wire mesh. The wire body is cylindrical and has a higher density in an outer circumferential region than in an inner region. This is intended to achieve sufficient strength of the connection between the outer region of the wire mesh and the cylindrical housing.

[0007] From JP 2009-162070 A, an exhaust aftertreatment device with a wire mesh body pressed into a housing is known. For positive locking of the wire mesh body, an inwardly projecting projection can be provided on the housing part.

[0008] During operation, an exhaust aftertreatment system is subjected to intense heat from the exhaust gases flowing through it. It has been observed that the preload applied when pressing the wire body into the housing, which secures the wire body within the housing, diminishes at the high temperatures generated during operation. Consequently, vibrations generated by the internal combustion engine on which the exhaust aftertreatment system is mounted can, in known exhaust aftertreatment units, cause the flow-through unit to loosen within the housing and no longer be reliably held in position. A 1-98002 / sta

[0009] (PA21548WO)

[0010] 2

[0011] The invention is based on the objective of creating an exhaust gas aftertreatment device of the generic type in which a secure fixation of the wire body is possible even after a longer operating time.

[0012] This problem is solved with respect to the exhaust aftertreatment device by an exhaust aftertreatment device having the features of claim 1.

[0013] The wire body is designed to have at least one first region with a first average density and at least one second region with a second average density. The second average density should be at least 1.5 times that of the first average density. The wire body is clamped at the second region between at least two clamping sections of the housing.

[0014] Because the second mean density is at least 1.5 times that of the first, the wire body exhibits significantly reduced elasticity in the second region. This allows the wire body to be clamped in place in the second region, resulting in a simpler design. Furthermore, because the second mean density is at least 1.5 times that of the first, the wire body experiences significantly less exhaust gas flow in the second region than in the first. Consequently, the second region, where the wire body is clamped, heats up less during operation. This reduced heating prevents the clamp from loosening during operation. Additionally, due to the increased density in the second region, the wire body's elasticity is comparatively low there.This allows for a secure fixation of the wire body in a simple way without additional fastening devices.

[0015] The flow unit can have one or more wire bodies. In particular, at least one wire body is a wire mesh. It may be provided that at least one wire body is a wire woven fabric. A 1-98002 / sta

[0016] (PA21548WO)

[0017] 3

[0018] Cavities are formed between the wire segments of the at least one wire body. The exhaust gas flows through these cavities via the flow unit. The cavities extend, in particular, to the outer surfaces of the wire body. Due to these cavities, the at least one wire body does not have a uniform density. The density of a region of the wire body is the average density of that region, which corresponds to the weight of the region divided by the volume of the surrounding material. The volume to which the density is referred includes both the wire segments and the cavities. The fewer cavities the wire body has, the greater its density.

[0019] In particular, the clamping mechanism provides for fixing the wire body between two clamping sections in a second area where the wire thickness is less than the distance between the clamping sections. For a round wire cross-section, the wire thickness corresponds to the wire diameter. The distance between the clamping sections is, in particular, at least twice, and especially at least three times, the wire thickness.

[0020] The wire body can be clamped at one point or at several spaced-apart points of the second region between each pair of clamping sections. The wire body can have several spaced-apart second regions. The wire body can be clamped at one or more of its second regions.

[0021] In particular, all wire bodies of the flow unit are held clamped in the clamping direction at a second area between two clamping sections of the housing.

[0022] The flow unit has, in particular, an inlet area. The inlet area is, in particular, an imaginary flat surface that abuts the flow unit. A 1-98002 / sta

[0023] (PA21548WO)

[0024] 4

[0025] In particular, the flow unit has an outflow surface. The outflow surface is, in particular, an imaginary flat surface that abuts the flow unit.

[0026] The outer surfaces of the wire body are uneven due to the presence of at least one wire body. The inlet surface and / or the outlet surface are, in particular, imaginary flat surfaces that abut the flow unit. The flow unit is located, in particular, between the inlet surface and the outlet surface. Specifically, the inlet surface and the outlet surface are opposite sides of an imaginary body that closely encloses the flow unit. The inlet surface and the outlet surface are, in particular, perpendicular to a principal flow direction through the inlet surface and the outlet surface, respectively.

[0027] The clamping direction has at least one directional component that runs perpendicular to the inlet surface. Therefore, the clamping direction is not parallel to the inlet surface, but forms an angle with it greater than 0°. Because the clamping direction has at least one directional component perpendicular to the inlet surface, the exhaust gas flow is not completely directed through the clamping surface. Specifically, the clamping direction runs perpendicular to the inlet surface. This allows the second section to be positioned outside the main flow path through the wire body. As a result, comparatively low heating of the second section during operation can be achieved.

[0028] The clamping direction has, in particular, at least one directional component that runs parallel to the main flow direction. The clamping direction is therefore not perpendicular to the main flow direction, but forms an angle with the main flow direction that is less than 90° or runs parallel to the main flow direction. Because the clamping direction has at least one directional component parallel to the main flow direction, the exhaust gas flow is not completely directed through the clamping surface. In particular, the clamping direction A 1-98002 / sta

[0029] (PA21548WO)

[0030] 5 parallel to the main flow direction. This allows the second area to be positioned outside the main flow path through the wire body. This results in comparatively low heating of the second area during operation.

[0031] Particularly when the inlet surface has an irregular or curved shape, the clamping direction is selected specifically with respect to the main flow direction. Especially when the main flow direction is undefined or curved, the clamping direction is selected specifically with respect to the inlet surface.

[0032] In particular, the second mean density is at least twice, and especially at least three times, the first mean density. The higher the second mean density, the lower the elasticity of the second region and the greater the flow resistance for exhaust gases. Therefore, increasing the second mean density can lead to improved fixation of the wire body.

[0033] In particular, the second area lies outside the flow path of the exhaust aftertreatment system. The flow path is the area of ​​the exhaust aftertreatment system that lies in the direct flow path from an inlet to an outlet. The second area may be fluidically connected to the flow path. However, the second area lies specifically outside the direct flow path of the exhaust gases. In particular, direct inflow into the second area via the inlet is not possible. In particular, direct outflow from the second area through the outlet is not possible. The exhaust gases do not need to flow through the second area to get from the inlet to the outlet.Due to the increased flow resistance of the second region, a flow path through the second region exhibits a flow resistance that is higher than the flow resistance of a direct flow path from the inlet opening through the flow area to the outlet opening. This allows for the simple heating of the two- A 1-98002 / sta.

[0034] (PA21548WO)

[0035] The volume in the sixth area is kept to a minimum. Sealing of the second area is specifically not planned. This results in a simple design for the flow unit.

[0036] In particular, the area of ​​at least one, and especially each, clamping section is at least 5%, and in particular at least 10%, of the area of ​​the flow-through region measured perpendicular to the inflow surface. In particular, the maximum extent of the second region of at least one wire body, measured perpendicular to the inflow surface, is smaller than the maximum extent of the first region, measured perpendicular to the inflow surface. In particular, the maximum extent of the second region, measured perpendicular to the inflow surface, is smaller for each wire body of the flow-through unit that is clamped between the two clamping sections than the maximum extent of the first region, measured perpendicular to the inflow surface.The increase in density in the second area can be easily achieved during the manufacture of the exhaust aftertreatment device by compressing the second area in a direction perpendicular to the inlet surface between the two clamping surfaces, using a wire body of constant thickness.

[0037] The second region, when viewed perpendicular to the inlet surface, extends around the first region. Specifically, in this viewing direction, the second region completely surrounds the first region. If the first region is cylindrical, the second region extends around the first region in an annular shape.

[0038] A simple design for the flow unit is achieved if the flow unit has an upstream end face to which the inlet surface rests, a downstream end face to which the outlet surface rests, and if the housing rests against at least one of the end faces. By having the housing rest against at least one of the end faces, bypass currents around the flow unit can be easily avoided. Ins- A 1-98002 / sta

[0039] (PA21548WO)

[0040] 7. In particular, the housing is located on both the upstream and downstream end faces of the flow unit.

[0041] In particular, the housing has at least one inlet opening on the upstream end face and at least one outlet opening on the downstream end face. The housing covers the upstream and / or downstream end face perpendicular to the respective end face in the direction of view, especially at an overlap area that extends along the edge of the end face and whose width is at least 0.5 mm. The overlap area extends, in particular, circumferentially along the entire edge of the respective end face.

[0042] The second section is positioned between the first section and a third section. The housing rests against the third section in such a way that the housing exerts a force from the first section towards the third section. This places the first section under tensile stress. During operation, vibrations act on the wire body, which can compress it when it rests against the housing. The tensile stresses counteract this compression. This at least partially prevents a reduction in the external dimensions of the first section of the wire body. The potential deformation of the wire body during operation can thus be easily counteracted by appropriately shaping the housing.

[0043] The maximum extent of the third region, measured perpendicular to the inlet surface, is in particular greater than the maximum extent of the second region, also measured perpendicular to the inlet surface. A force from the first region towards the third region can be easily generated by the fact that the extent of the housing, measured perpendicular to the inlet surface, increases with increasing distance from the first region in the area adjacent to the third region. The housing in the area adjacent to the third region can, for example, have a cross-sectional shape of a slope or ramp. For cylindrical shapes, A 1-98002 / sta

[0044] (PA21548WO)

[0045] 8. Due to the first section of the wire body, the housing in the area adjacent to the third section can, for example, have the shape of a cone in the section.

[0046] In particular, the inlet and outlet surfaces are approximately parallel to each other within the usual manufacturing tolerances. The flow unit has a total thickness. This total thickness is the greatest extent of the flow unit measured perpendicular to the inlet surface, from the inlet surface to the outlet surface. The outlet surface deviates from a path parallel to the inlet surface by no more than 5% of the total thickness at any point. The end faces of the flow unit may be slightly curved. In particular, a slightly concave shape of the inlet and / or outlet surface is provided. Alternatively, the end faces may be flat within the usual manufacturing tolerances. In particular, the upstream end face does not deviate from the inlet surface by more than 5% of the total thickness at any point.Alternatively or additionally, it is specifically stipulated that the downstream end face must not deviate at any point by more than 5% of the total thickness from the outflow surface.

[0047] A different geometry for the flow unit can also be advantageous. In particular, the flow unit can be at least partially curved. It is also possible for the flow unit to have an irregular shape. This can be particularly useful for adapting it to an existing installation space.

[0048] It may be provided that the flow unit is at least partially 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 that contains a precious metal. It may be provided that the flow unit is at least partially coated with a washcoat. A washcoat is not considered a catalytic coating in this context. A 1-98002 / sta

[0049] (PA21548WO)

[0050] 9

[0051] Layering is considered. A washcoat is defined as a coating that increases the surface area without lowering the activation energy for the chemical reaction. A washcoat coating can serve as a substrate or bonding surface for a catalytic coating. However, it can also be provided that at least one wire body, in particular all wire bodies of the flow unit, are coated only with washcoat and have no catalytic coating. It can also be provided that the flow unit has at least partial lack of a coating. In particular, it is provided that the flow unit is not completely coated with a catalytic coating. This allows the manufacturing costs of the flow unit to be kept comparatively low.

[0052] For a method of manufacturing an exhaust aftertreatment device, it is particularly provided that the at least one wire body in the second area between the two clamping sections of the housing is compressed to the second density. In particular, all wire bodies of the flow unit between the two clamping sections of the housing are compressed to the second density.

[0053] In particular, a blank of the flow unit, comprising at least one wire body with a uniform average density within the usual manufacturing tolerances, is placed between at least two blank housing parts, and the compression of the flow unit and the shaping of the housing are carried out in a single forming process. Specifically, all wire bodies of the flow unit are compressed in a single forming process along with the shaping of the housing.

[0054] After the housing parts have been shaped, they are firmly joined together. This joining can be achieved by welding, soldering, positive locking, or friction locking. Specifically, the housing parts are joined as described in A 1-98002 / sta

[0055] (PA21548WO)

[0056] 10 interconnected, such that the housing parts cannot be separated from each other without damaging the housing parts.

[0057] Exemplary embodiments of the invention are explained below with reference to the drawing. The drawing shows:

[0058] Fig. Al is a schematic sectional view of a chainsaw with a

[0059] Exhaust silencer and an exhaust aftertreatment system,

[0060] Fig. A2 is a perspective sectional view of the exhaust silencer from Fig. A1.

[0061] Fig. A3 is a schematic top view of the exhaust aftertreatment device of the exhaust silencer from Fig. A2,

[0062] Fig. A4 shows a partial view of an exemplary wire body,

[0063] Fig. A5 is a perspective sectional view of an embodiment of an exhaust aftertreatment device on the partition wall of an exhaust silencer,

[0064] Fig. A6 shows a section through the exhaust aftertreatment system.

[0065] Fig. A5,

[0066] Figs. A7 and A8 are schematic representations of a method for manufacturing the exhaust aftertreatment device in different process steps, A 1-98002 / sta

[0067] (PA21548WO)

[0068] 11

[0069] Fig. A9 shows a perspective sectional view of another embodiment of an exhaust silencer,

[0070] Fig. A10 is a schematic representation of an embodiment of a

[0071] Exhaust aftertreatment system during manufacturing, the illustration showing the state before forming,

[0072] Figs. A1 to A13 schematic representations of possible alternative forms of flow unit and housing,

[0073] Fig. A14 shows a top view of the exhaust silencer,

[0074] Fig. Al 5 shows a perspective view of an outlet scoop of the exhaust silencer,

[0075] Fig. Al 6 shows a partial sectional view of the exhaust silencer in the area of ​​the outlet scoop.

[0076] In figures Al to A16, the reference symbols mentioned below are shown without the leading letter A.

[0077] Fig. Al shows a chainsaw Al as an exemplary embodiment of a hand-held power tool. Instead of the chainsaw Al, another hand-held power tool, for example an angle grinder, a cutter, a blower, or a lawnmower, could also be used. The power tool is, in particular, a hand-held tool used during operation.

[0078] The chainsaw Al has a housing A2 on which a handle A3 is arranged. The handle A3 is used to guide the chainsaw Al during operation. Operating elements are attached to the handle A3, in this exemplary embodiment a throttle lever A4 and a throttle lever A 1-98002 / sta

[0079] (PA21548WO)

[0080] 12 lock A5, arranged. An internal combustion engine A8 is arranged in housing A2. The internal combustion engine A8 can be controlled by an operator using the operating elements. The internal combustion engine A8 drives a tool, namely a saw chain A7 arranged circumferentially on a guide rail A6. The saw chain A7 is shown only schematically in Fig. A1.

[0081] The internal combustion engine A8 comprises an air filter A9 and a fuel supply device A10. The internal combustion engine A8 includes an intake duct Al1, through which air is drawn in via the air filter A9 during operation. A section of the intake duct Al1 is formed within the fuel supply device A10. The fuel supply device A10 can, for example, be a carburetor.

[0082] The internal combustion engine A8 comprises a cylinder A12, in which a combustion chamber Al4 is formed. The combustion chamber A14 is bounded by a piston Al3, which is mounted to reciprocate within the cylinder A12. The piston Al3 drives, via a connecting rod Al6, a crankshaft Al7, which is rotatably mounted in a crankcase Al5 about a pivot axis Al8. The crankshaft Al7 serves to drive the saw chain A7.

[0083] In the exemplary embodiment, the internal combustion engine A8 is designed as a two-stroke engine, specifically as a single-cylinder engine. The intake port Al 1 opens into the interior of the crankcase A15. The connection between the intake port Al 1 and the crankcase A15 is controlled by the piston A13. The internal combustion engine A8 comprises several transfer ports Al 9, which fluidically connect the interior of the crankcase Al 5 to the combustion chamber A14 in the region of the bottom dead center of the piston A13. An exhaust port A21 leads from the combustion chamber A14 and is connected to an exhaust silencer A23 via an exhaust port A22. The exhaust port A21 is controlled by the piston A13. A spark plug A20, which is controlled by a control device (not shown), protrudes into the combustion chamber A14. A 1-98002 / sta

[0084] (PA21548WO)

[0085] 13

[0086] The exhaust silencer A23 includes an inlet opening A24 through which exhaust gases from the outlet channel A22 enter the exhaust silencer A23. An outlet opening A25 leads from the exhaust silencer A23, through which the exhaust gases escape into the environment. The outlet opening A25 can, for example, be formed on an outlet scoop A76, as shown in Fig. A2.

[0087] In the exemplary embodiment, the exhaust silencer A23 has a silencer housing A27 in which a partition A26 runs. The partition A26 separates a first silencer chamber A30 from a second silencer chamber A31. An exhaust aftertreatment device A32, which will be described in more detail below, is arranged in the partition A26. Exhaust gases flow through the exhaust aftertreatment device A32 in a main flow direction A35. The exhaust aftertreatment device A32 includes a flow unit A33 through which the exhaust gases flow from the first silencer chamber A30 into the second silencer chamber A31.

[0088] Fig. A2 shows the exhaust silencer A23 in detail in a perspective sectional view. The silencer housing A27 comprises a first partial shell A28 and a second partial shell A29, which are connected to each other at a circumferential rim A53. The partition A26 runs between the partial shells A28 and A29 and, in the exemplary embodiment, is also fixed at the rim A53.

[0089] The exhaust aftertreatment device A32 is held on the partition wall A26. In the embodiment shown in Fig. A2, the exhaust aftertreatment device A32 has a circumferential rim A54. The partition wall A26 has an opening A55 through which the exhaust aftertreatment device A32 projects. The rim A54 of the exhaust aftertreatment device A32 overlaps the partition wall A26 and is fixed to it, for example by a weld.

[0090] The exhaust aftertreatment unit A32 has a housing A34. The housing A34 is formed by two housing parts A56 and A57. Another design of the A 1-98002 / sta

[0091] (PA21548WO)

[0092] 14

[0093] Housing A34 can, however, be advantageous. The two housing parts A56 and A57 can, for example, be designed as deep-drawn parts or as stamped parts. The two housing parts A56 and A57 are connected to each other at the edge A54. In the exemplary embodiment, the two housing parts A56 and A57 abut each other at the edge A54 and together form the edge A54.

[0094] The first housing part A56 has an inlet opening A51 for exhaust gases. The inlet opening A51 can be formed by several individual openings in the first housing part A56. The second housing part A57 has an outlet opening A52, which can also be formed by several individual openings. In the exemplary embodiment, the inlet opening A51 and outlet opening A52 are subdivided by several housing struts A70.

[0095] The flow unit A33 is arranged in the housing A34. The flow unit A33 can be formed in one piece or comprise several sub-bodies. In particular, the flow unit A33 consists of one or more dimensionally stable bodies. The flow unit A33 has at least one wire body. In the exemplary embodiment, a first wire body A36 and a second wire body A40 are provided. At least one of the wire bodies A36, A40, and in particular both wire bodies A36 and A40, can be a wire mesh. The wire bodies A36 and A40 can be uncoated, coated with washcoat, or provided with washcoat and a catalytic coating. It is possible for the first wire body A36 and the second wire body A40 to have the same coating.Alternatively, the wire bodies A36 and A40 may have different coatings, or one of the wire bodies A36, A40 may have a coating while the other wire body A36, A40 does not. In particular, one of the wire bodies may have a larger quantity of catalytic coating per volume of wire body A36, A40 than the other of the two wire bodies A36, A40. It may also be provided that the other of the wire bodies A36, A40 does not have a catalytically active coating. A 1-98002 / sta.

[0096] (PA21548WO)

[0097] 15

[0098] The first wire body A36 has an upstream end face A49. In the exemplary embodiment, the end face A49 is flat and coincides with an inlet surface A44 in the flow unit A33. The inlet surface A44 is an imaginary plane that abuts the end face A49. The inlet surface A44 is one side of a housing body that closely encloses the wire bodies A36 and A40. The housing A34 has the inlet opening A51 on the end face A49.

[0099] In the exemplary embodiment, the second wire body A40 rests against the first wire body A36. The second wire body A40 is arranged downstream of the first wire body A36 with respect to the main flow direction A35. In this exemplary embodiment, both wire bodies A36 and A40 are identically shaped. However, wire bodies of different shapes, preferably with different thicknesses measured perpendicular to the inlet surface A44, can also be provided. The second wire body A40 has a downstream end face A50, which in this exemplary embodiment is flat. The downstream end face A50 coincides with an imaginary flat outlet surface A45. The housing A34 has the outlet opening A52 on the end face A50.

[0100] During operation, exhaust gases flow from the first silencer chamber through the inlet opening A51 and the end face A49 into the first wire body A36, flow through the first wire body A36, flow from the first wire body A36 into the second wire body A40, and from the second wire body A40 through the end face A50 into the second silencer chamber A31. The exhaust gases leave the exhaust aftertreatment device A32 through the outlet opening A52 of the housing A34. The exhaust gases flow from the inlet opening A51 to the outlet opening A52 in the main flow direction A35. The end faces A49 and A50 are approximately planar. The inlet surface A44 and the outlet surface A45 are, within the limits of manufacturing tolerances, approximately parallel to each other. The inlet surface A44 and the outlet surface A45 are defined by the imaginary planar surfaces A 1-98002 / sta

[0101] (PA21548WO)

[0102] 16

[0103] Enveloping surfaces are formed that bear against the individual wire windings of the wire bodies A36 and A40. In Fig. A2, the wire bodies A36 and A40 are shown as solid bodies for the sake of simplicity. The outlines of the solid bodies correspond to the envelope that forms the inlet surface A44 and the outlet surface A45.

[0104] The flow unit A33 has a total thickness e. The total thickness e is the maximum thickness of the flow unit A33 perpendicular to the inlet surface A44 and measured from the inlet surface A44 to the outlet surface A45.

[0105] The first wire body A36 has a first region A37, which forms the end face A49. The first region A37 of the first wire body A36 is the region of the first wire body A36 through which the exhaust gases flow. The second wire body A40 has a first region A41 through which the exhaust gases flow and which forms the end face A50. The first region A37, A41 of the wire bodies A36, A40 has a first density. The density is the weight of the respective region divided by the total volume. The total volume includes the volume of the wire and any cavities located between the wire loops.

[0106] The wire bodies A36 and A40 each have a second region A38, A42, the density of which is considerably greater than the density of the first region. The density of the second region A38, A42 is at least 1.5 times, in particular at least 2 times, in particular at least 3 times, in particular at least 5 times the first average density of the first region A37 or A41. The second region A38 and A42 of the wire bodies A36 and A40 is arranged outside a flow-through region A48, through which the exhaust gases flow in the main flow direction A35 from the inlet opening A51 to the outlet opening A52. At the second regions A38 and A42, the wire bodies A36 and A40 are clamped between clamping sections A46 and A47 of the housing A34 in a clamping direction A62. Further clamping sections may also be provided. In the exemplary embodiment, the first areas A37 and A40 are approximately cylindrical and the second areas A 1-98002 / sta

[0107] (PA21548WO)

[0108] 17

[0109] A38 and A42 each surround the first areas A37 and A41 in a ring-like fashion. The clamping sections A46 and A47 are ring-shaped recesses in the housing parts A56 and A57. The clamping sections A46 and A47 are opposite each other in a direction perpendicular to the inlet surface A44 with respect to the wire body A36, A40.

[0110] The clamping direction A62 has at least one directional component that runs perpendicular to the inlet area A44. In the exemplary embodiment, the clamping direction A62 runs perpendicular to the inlet area A44. In the exemplary embodiment, the clamping direction A62 runs perpendicular to the outlet area A45.

[0111] The clamping direction A62 has at least one directional component that runs parallel to the main flow direction A35. In the exemplary embodiment, the clamping direction A62 runs parallel to the main flow direction A35.

[0112] The main flow direction A35 runs perpendicular to the inlet surface A44.

[0113] The area of ​​at least one, in particular each, clamping section A46, A47 is at least 5%, in particular at least 10% of an area of ​​the flow area A48 measured when looking perpendicular to the inlet area A44.

[0114] Wire bodies A36 and A40 each have a third section A39, A43. The second section A38 and A42 of each wire body A36 and A40 is located between the first section A37, A41 and the third section A39, A43 of that wire body A36, A40. The second section A38, A42, with its comparatively high density, thus separates the first sections A37, A40 from the third sections A39, A43. The third sections A39, A43 also lie outside the flow area A48. Exhaust gases can flow into the second section A38, A42 and through it into the third section A39, A43. However, no exhaust gases escape from the second section A38, A42 or the third section A39, A43. A 1-98002 / sta

[0115] (PA21548WO)

[0116] 18

[0117] Opening, so that the exhaust gases must flow back into the first areas A37, A41 in order to leave the flow unit A33.

[0118] As shown in Fig. A2, the maximum extent b of each second region A38, A42, measured perpendicular to the inlet surface A44, is smaller than the maximum extent a of each first region A37, A41, also measured perpendicular to the inlet surface A44. In Fig. A2, the extents a and b are shown only for the first wire body A36, since the second wire body A40 has identical dimensions in the exemplary embodiment. The second regions A38, A42 can be produced by compressing the wire body A36, A40 in a direction perpendicular to the inlet surface A44.

[0119] As the schematic representation in Fig. A3 shows, the second region A38 runs around the first region A37. The third region A39 runs in a circular ring around the second region A38. Fig. A3 shows a schematic view of the first wire body A36 viewed perpendicular to the inlet surface A44.

[0120] As shown in Fig. A2, the housing A34 abuts the flow unit A33 at both the upstream end face A49 and the downstream end face A50. The housing covers the end faces A49 and A50 at their circumferential edges in an overlap area A60. The overlap area A60 extends along the edge of the respective end face A49 or A50, in particular circumferentially. The width h of the overlap area A60 is at least 0.5 mm at least at one point, and in particular at every point of the overlap area A60. In Fig. A2, the overlap area A60 is shown only for the downstream end face A50.

[0121] As Fig. A2 also shows, the housing A34 has areas A58 and A59 adjacent to the third area A39, A43. Areas A58 and A59 are inclined towards the main flow direction A35. The angle of inclination is greater than 0° and less than A 1-98002 / sta

[0122] (PA21548WO)

[0123] 19 as 90°. In particular, the angle of inclination is from 20° to 70°. Due to the rotationally symmetrical shape of the flow unit A33, the housing wall in the exemplary embodiment has a conical segment shape. During the manufacture of the exhaust aftertreatment device A32, a force F is exerted on the third areas A39 and A42 due to the inclined shape of the sections A58 and A59. Due to this force F, the second areas A38, A42 and the first areas A37, A41 are under tensile stress.

[0124] The flow unit A33 is clamped in the housing A34. This causes both the clamping sections A46 and A47, as well as the adjacent areas A58 and A59, which are inclined towards the main flow direction A35, to exert a clamping force. The force F exerted by areas A58 and A59 is radially outwards, as schematically illustrated in Fig. A3. The force F exerted by the inclined areas A58 and A59 of the housing A34 on the first areas A37 and A41 of the flow unit A33 therefore places these areas under tensile stress and counteracts a reduction in the size of these areas due to vibrations and / or heating from the exhaust gas temperature during operation.

[0125] The third region A39, A43 has a maximum extent c measured perpendicular to the inlet surface A44. In particular, the third region A39, A43 has its maximum extent c at the outer circumference of the flow unit A33. The maximum extent c of the third region A39, A43 is, in particular, greater than the maximum extent b of the second region A38, A42, measured perpendicular to the inlet surface A44. The extent d of the housing A34, measured perpendicular to the inlet surface A44, increases, in particular in the regions A58, A59 adjacent to the third region, with increasing distance from the first region A37, A41. In particular, at least part of the regions A58 and A59 of the housing A34 has a uniform profile inclined to the main flow direction A35. A 1-98002 / sta

[0126] (PA21548WO)

[0127] 20

[0128] Fig. A4 shows an exemplary design of a wire body using the first wire body A36 as an example. The wire body A40 is designed identically. The wire body A36 is constructed of metal wire. In particular, the wire body A36 is a metal mesh. Gaps are formed between the individual wire loops through which the exhaust gas can flow. The lower the average density of the wire body, the greater the proportion of the gaps to the flow cross-section of the wire body A36, A40. The wire of the wire body A36 has a thickness i. In particular, the wire has a round cross-section, and the thickness i corresponds to the diameter of the wire. The clamping sections A46 and A47 have a distance k, as shown in Fig. A2. The distance k is in particular at least twice, and in particular at least three times, the thickness i.

[0129] Fig. A5 shows an embodiment of an exhaust aftertreatment device A32. The same reference numerals denote corresponding elements in all embodiments. In the embodiment shown in Fig. A5, the flow unit A33 comprises a single wire body A36. Alternatively, several wire bodies A36 can be provided in this embodiment as well. The housing A34 of the exhaust aftertreatment device A32 is formed by two housing parts A56 and A57. Housing part A56 forms a circumferential wall A71 on the third region A39 of the wire body A36. Housing part A57 lies within the circumferential wall A71. Housing part A56 has tabs A61 that are bent over and thereby fix housing part A57 to housing part A56. This achieves a positive-locking connection.

[0130] As Fig. A5 also shows, in this embodiment the flow unit A33 has a cross-section in the form of a rounded rectangle. The partition A26 has a bent edge A69 in the area that delimits the opening A55. The flow unit A33 is fixed to the bent edge A69 with its circumferential wall A71. In an alternative embodiment, the partition A26 and the housing part A56 can be formed integrally. A 1-98002 / sta

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[0132] 21

[0133] The connection of housing parts A56 and A57 of housing A34 can be achieved by a material-bonded connection, for example by welding or soldering, by a positive-locking connection, or by a friction-locking connection. In the embodiment according to Fig. A5, a positive-locking connection is provided by bending the tabs A61. In the embodiment according to Fig. A2, the housing parts A56 and A57 can, for example, be welded together.

[0134] As shown in Fig. A6, the upstream end face A49 and the downstream end face A50 are not flat, but slightly convex. The inlet area A44 abuts the end face A49. The inlet area A44 is shown with a dashed line in Fig. A6. The inlet area A44 abuts the end face A49 at its circumference. The outlet area A45 is also shown with a dashed line in Fig. A6. The outlet area A45 abuts the end face A50 at its circumference. In this embodiment, both the end face A49 and the end face A50 are concave. The end faces A49 and A50 deviate by a deviation g from a flat profile defined by the inlet area A44 and the outlet area A45. In this embodiment, the deviation g is greatest in the middle of the end faces A49 and A50.The largest deviation g is, in particular, less than 5% of the total thickness e of the flow unit A33. The end faces A49 and A50 may also be slightly angled to each other or otherwise irregular. In particular, the outlet surface A45 does not deviate at any point from a path parallel to the inlet surface A44 by more than 5% of the total thickness e.

[0135] Figures A6 and 7 show process steps of a method for manufacturing the flow-through unit A33. A wire body A36 is placed between two housing parts A56 and A57. A first housing part A56 is arranged in a die A64, the shape of which corresponds to the outer contour of the finished flow-through unit A33. The housing part A56 can be pre-formed, as shown. In particular, the A 1-98002 / sta

[0136] (PA21548WO)

[0137] 22

[0138] Housing part A56, however, is inserted as a flat sheet metal part. A second housing part A57 is arranged in a punch A65. In particular, the second housing part A57 is also arranged as a blank, specifically as a flat sheet metal part, on the punch A65. However, it can also be provided that the second housing part A57 is already pre-formed as shown. The tool for manufacturing the flow unit A33 also has lateral slides A66. The punch A65 is movable in the direction of arrow A67 towards the die A64. The slides A66 are movable towards each other in the direction of arrows A68 and perpendicular to arrow A67. As Fig. A7 shows, the wire body A36 has a uniform overall thickness e' before pressing. The overall thickness e' is greater than the thickness e (Fig. A6).

[0139] Fig. A8 shows the arrangement after the punch A65 has been moved into the die A64 and the slides A66 have moved towards each other. The die A64 and the punch A65 have clamped the wire body A36 between the housing parts A56 and A57. In doing so, both the first section A37 was compressed and the second section A38 was compressed to the second density between the clamping sections A46 and A47. The third section A39 of the wire body A36 was also compressed between the housing parts A56 and A57. After compression, the slides A66 bent the tabs A61 over, thus fixing the wire body A36 between the housing parts A56 and A57.

[0140] Fig. A9 shows an embodiment of an exhaust silencer A23 with an exhaust aftertreatment device A32. The exhaust aftertreatment device A32 is arranged in an opening A55 of the partition A26. The housing parts A56 and A57 are separately fixed to the bent edge A69 of the partition A26, for example by welded connections. In the embodiment according to Fig. A9, the housing parts A56 and A57 do not touch and are only connected to each other via the edge A69 of the partition A26. In the embodiment according to Fig. A9, the wire body A36 comprises only a first section A37 and a second section A38. A third section A39 is not present in this embodiment. A 1-98002 / sta

[0141] (PA21548WO)

[0142] 23

[0143] The clamping sections A46 and A47 extend to the circumference of the housing parts A56 and A57. In the exemplary embodiment, the clamping sections A46 and A47 run approximately parallel to each other. The further design of the exhaust aftertreatment device A32 can be provided as in the preceding exemplary embodiments.

[0144] Fig. A10 shows an embodiment of a flow-through unit A33 before the forming of the housing parts A56 and A57 and before the forming of the wire body A36. The wire body A36 is positioned between two housing parts A56 and A57. Both housing parts A56 and A57 are designed as flat sheet metal parts and are formed together with the flow-through unit A33 in a single process step. After forming, the flow-through unit A33 can, for example, have the shape shown in Fig. A2.

[0145] Figures 11 to 13 show alternative designs for the shape of first section A37 and housing A34. In the embodiment according to Fig. A1 1, housing A34 and first section A37 have different shapes. In this embodiment, first section A37 is circular, and housing A34 is square or rectangular with rounded corners. The resulting clamping section A46 therefore does not have a uniform width. The clamping section A47, which is not visible in the illustrations in Figs. A1 to A3, is specifically identical in shape to the respective clamping section A46.

[0146] In the exemplary embodiment, the first region A37 has a circular or elliptical shape, and the housing A34 has a square or rectangular shape, particularly with rounded corners. The first region A37 projects to the edge of the housing A34 at least at one point, in the exemplary embodiment at four points. This results in four separate clamping sections A46 in the corner regions of the housing A34. A 1-98002 / sta

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[0148] 24

[0149] In the embodiment shown in Fig. Al 3, the housing A34 is round or elliptical, and the first region A37 is designed as a rectangle or square, particularly with rounded corners. The first region A37 extends to the edge of the housing A34. In this embodiment, four separate clamping sections A46 are formed.

[0150] A design with two opposing clamping areas A46, which may be arranged, for example, on the longitudinal sides of a rectangular first area A37 or housing A34, or with three clamping areas A46, which may be arranged, for example, in the area of ​​the tips of a triangular first area A37 or housing A34, may also be advantageous.

[0151] In the embodiments shown in Figures Al 1 to Al 3, the clamping area A46 is locally designed with a reduced width or is completely interrupted. This allows the housing A34 to be smaller compared to a design with a clamping area A46 of constant width all around. This, in turn, reduces the weight of the flow unit A33.

[0152] Figures A to B 16 show the design of an outlet scoop A76 of the exhaust silencer A23, on which the outlet opening A25 is formed. The internal combustion engine A8 has a reference plane A80 with respect to the exhaust gas temperature to be achieved, which is shown schematically in Fig. A14. The reference plane A80 is an imaginary plane that abuts the internal combustion engine A8 at at least three points. The outlet opening A25 has a distance s to at least one, and in particular to all, reference planes A80 that can be arranged downstream of the outlet opening A25 in the outflow direction A78 on the internal combustion engine A8. The distance s is in particular at least A50 mm. This is particularly advantageous when the exhaust silencer A23 is arranged in a chainsaw A1. A 1-98002 / sta

[0153] (PA21548WO)

[0154] 25

[0155] A projection A77 is arranged on the silencer housing A27. The projection A77 extends at a distance t from the outlet opening A25 in the outflow direction A78. In the exemplary embodiment, the projection A77 is designed as a raised rib. As shown in Fig. A5, the projection A77 is formed integrally with the outlet scoop A76 as a raised edge of the sheet metal part that forms the outlet scoop A76. The projection A77 extends transversely, and in particular approximately perpendicularly, to the outflow direction A78 in at least one section. The projection A77 runs at least partially parallel to the surface of the outlet opening A25.

[0156] The elevation A77 has a width m measured perpendicular to the outflow direction A78. The width m is, in particular, larger than the width k of the outlet opening A25.

[0157] The protrusion A77 extends, in the outflow direction A78, particularly beyond the outlet opening A25. In the exemplary embodiment, the protrusion A77 extends with a rounded edge beyond the plane of the outlet opening A25.

[0158] The height o of the elevation is in particular 15% to 20% of the height n of the exit window A25, as shown in Fig. Al 6.

[0159] The outlet scoop A76 has a length p measured in the outflow direction A78. A shoulder A79 is formed on the silencer housing A27. The shoulder A79 forms, in particular, a separation edge for the exhaust gas flow. In the exemplary embodiment, the shoulder A79 is formed by a kink in the silencer housing, at which the silencer housing A27 dips below the plane of the outflowing exhaust gases. The shoulder A79 has a distance r from the outlet opening A25, which corresponds, in particular, to at least the length p of the outlet scoop A76. A distance t from the projection A77 to the outlet opening A25, measured in the outflow direction A78, is, in particular, less than the length p of the outlet scoop A76.

[0160] Further advantageous embodiments result from any combination of the elements of the embodiments described above. A 1-98002 / sta

[0161] (PA21548WO)

[0162] 26

[0163] The invention further relates to an exhaust aftertreatment device of the type specified in the preamble of claim 11, an exhaust silencer and a method for manufacturing an exhaust aftertreatment device.

[0164] 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.

[0165] 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.

[0166] 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.

[0167] 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. A 1-98002 / sta

[0168] (PA21548WO)

[0169] 27

[0170] 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°.

[0171] 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. A 1-98002 / sta.

[0172] (PA21548WO)

[0173] 28

[0174] 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.

[0175] 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.

[0176] 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.

[0177] Advantageously, the exhaust aftertreatment system is designed such that each partial flow of exhaust gas passing through the system 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 flow through the system.

[0178] 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 to each other is advantageous solely for creating a defined clamping of the A 1-98002 / sta.

[0179] (PA21548WO)

[0180] 29

[0181] A flow-through unit is provided during the manufacture of the exhaust aftertreatment system. Advantageously, a displacement of the contact surfaces relative to each other during operation of the exhaust aftertreatment system is not provided.

[0182] 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.

[0183] If the flow unit has several sub-sections, it is particularly preferred that each sub-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 A 1-98002 / sta

[0184] (PA21548WO)

[0185] 30 and / or a catalytically active coating. This allows for simple production of the coating, for example in an immersion process.

[0186] 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.

[0187] 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.

[0188] 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. A 1-98002 / sta

[0189] (PA21548WO)

[0190] 31

[0191] For an exhaust silencer, it is provided that the exhaust silencer has an exhaust inlet, an exhaust outlet and an exhaust aftertreatment device arranged in the flow path between the exhaust inlet and the exhaust outlet.

[0192] 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.

[0193] 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.

[0194] Advantageously, the movement of the housing sections towards each other is controlled.

[0195] The housing sections are advantageously moved towards each other until a predetermined...

[0196] The distance between the clamping surfaces is reached. This is particularly advantageous when - A 1-98002 / sta

[0197] (PA21548WO)

[0198] 32. This is problematic if the exhaust aftertreatment device, in its finished state, is to have a predetermined dimension, for example, to maintain a predetermined flow length or path between the at least one inlet opening and the at least one outlet opening. An alternative method may involve moving the housing sections towards each other under force control. For this purpose, the housing sections are advantageously moved towards each other until a predetermined force for displacement is achieved. This allows a clamping action with a predetermined force or preload to be set. This is particularly advantageous if 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 good clamping between the housing sections, even with large dimensional tolerances of the flow unit.

[0199] Exemplary embodiments of the invention are explained below with reference to the drawing. The drawing shows:

[0200] Fig. Bl is a schematic sectional view of a chainsaw,

[0201] Fig. B2 is a perspective view of the exhaust aftertreatment device of the exhaust silencer of the chainsaw from Fig. Bl.

[0202] Fig. B3 shows a side view of the exhaust aftertreatment system.

[0203] Fig. B2,

[0204] Fig. B4 is a perspective exploded view of the exhaust aftertreatment system from Fig. B2,

[0205] Fig. B5 is an exploded view of the exhaust aftertreatment system in side view, A 1-98002 / sta

[0206] (PA21548WO)

[0207] Fig. B6 is an enlarged sectional view through the exhaust gas aftertreatment device from Fig. B2,

[0208] Fig. B7 shows a partial view of a wire body of the through-

[0209] Flow unit,

[0210] Figs. B8 and B9 are perspective sectional views of the exhaust aftertreatment system in different states during manufacturing.

[0211] Fig. BIO shows a side view of an exemplary embodiment of an exhaust aftertreatment device,

[0212] Fig. B1 is a perspective sectional view through the exhaust aftertreatment system from Fig. BIO.

[0213] Fig. B 12 is a perspective view of the exhaust aftertreatment system from Fig. BIO,

[0214] Figs. B13 to B15 are perspective views of an outlet bowl of the exhaust aftertreatment system from Fig. BIO.

[0215] In figures Bl to B 15, the reference symbols mentioned below are shown without the leading letter B.

[0216] Fig. Bl shows, as an embodiment of a hand-held, preferably hand-carried, power tool, a chainsaw B 1. The present invention can also be used with other hand-held, preferably hand-carried power tools, such as angle grinders, brush cutters, or blowers. A 1-98002 / sta

[0217] (PA21548WO)

[0218] 34

[0219] It can also be used with ground-based work equipment such as lawnmowers.

[0220] The chainsaw Bl has a housing B2, on which a rear handle B3 is arranged for guiding and carrying the chainsaw Bl during operation. Operating elements, in this exemplary embodiment a throttle lever B4 and a throttle lock B5, are arranged on the rear handle B3. The chainsaw Bl has a guide bar B6 on which a saw chain B7 is arranged. During operation, the saw chain B7 is driven around the guide bar B6 by a drive motor B8 located in the housing B2. The drive motor B8 is advantageously a single-cylinder engine. The drive motor B8 is particularly a two-stroke engine.

[0221] The term "equipment housing" is to be understood broadly in this context and refers to a structure that can hold elements of the chainsaw Bl and at least partially enclose them from the environment. The equipment housing B2 can be open to the environment and can be made up of multiple parts. Preferably, the equipment housing B2 comprises several sections arranged to be movable relative to one another and connected to each other via vibration elements.

[0222] The drive motor B8 has a cylinder B12 in which a combustion chamber B14 is formed. The combustion chamber B14 is bounded by a piston B13 which is driven reciprocatingly within the cylinder B12. The piston B13 drives a crankshaft B17, which is rotatably mounted in a crankcase B15 about a pivot axis B18, via a connecting rod B16. The piston B13 controls the connection of the intake port Bl1 to the interior of the crankcase Bl5. The piston B13 controls an exhaust port B21, which leads from the combustion chamber B14. The interior of the crankcase B15 is connected to the combustion chamber B14 via at least one transfer port B19 in at least one position of the piston Bl13, preferably when the piston B13 is in the region of bottom dead center. A spark plug B20 projects into the combustion chamber B14. A 1-98002 / sta

[0223] (PA21548WO)

[0224] 35

[0225] The drive motor B8 includes an air filter B9 through which air is drawn in during operation. In the exemplary embodiment, a fuel supply device BIO is provided for supplying fuel. During operation, the drive motor B8 draws air through the air filter B9 and an intake duct Bl 1 into the crankcase B 15. A section of the intake duct Bl 1 is formed in the fuel supply device BIO, for example, a carburetor. Other designs of the fuel supply device BIO, for example, as a fuel valve, are also possible. Alternative arrangements of the fuel supply device BIO may also be advantageous. The fuel supply device BIO can supply the fuel into the intake duct Bl 1, into the interior of the crankcase B 15, into a transfer duct B 19, and / or a combustion chamber B 14 of the drive motor B8.

[0226] During the operation of the drive motor B8, on the upward stroke of piston B13, fuel / air mixture is drawn into the crankcase B15 via intake port Bl1 in the exemplary embodiment. On the downward stroke of piston B13, the fuel / air mixture is compressed in the crankcase B15. As soon as the transfer ports B19 from piston B13 to combustion chamber B14 open, fuel / air mixture flows into combustion chamber B14. On the subsequent upward stroke of piston B13, the fuel / air mixture is compressed in combustion chamber B14 and ignited by spark plug B20 near the top dead center of piston B13. The resulting combustion accelerates piston B13 towards crankcase Bl5. The exhaust port B21 leads into an exhaust port B22, which in turn leads to an exhaust silencer B23. The exhaust silencer B23 is fixed to cylinder B12.As soon as the exhaust port B21 is opened by the piston B13, exhaust gases can flow into the exhaust silencer B23 via the exhaust channel B22.

[0227] The exhaust silencer B23 has an exhaust inlet B24, which in the exemplary embodiment leads into a first silencer chamber B48. It is possible to arrange further silencer chambers between the exhaust inlet B24 and the first silencer chamber B48. The first silencer chamber B48 is enclosed by an A 1-98002 / sta

[0228] (PA21548WO)

[0229] The second silencer chamber B49 is separated by a partition B28. The exhaust silencer B23 includes an exhaust aftertreatment unit B26. In the exemplary embodiment, the exhaust aftertreatment unit B26 is arranged in the partition B28. The exhaust aftertreatment unit B26 comprises a housing B27 in which a flow-through unit B31 is arranged. In the exemplary embodiment, the exhaust gases flow from the first silencer chamber B48 through the exhaust aftertreatment unit B26 into the second silencer chamber B49. The exhaust gases then flow through the flow-through unit B31.

[0230] An exhaust outlet B25 leads from the exhaust silencer B23. The exhaust outlet B25 can lead from the second silencer chamber B49. However, it is also possible that further silencer chambers are arranged in the direction of flow between the second silencer chamber B49 and the exhaust outlet B25.

[0231] Figures B2 to B6 show the detailed design of the exhaust aftertreatment device B26. As shown in Figure B2, the housing B27 of the exhaust aftertreatment device B26 has a plurality of outlet openings B30. Exhaust gases can flow out of the housing B27 through these outlet openings B30. A single outlet opening B30 can also be advantageous. In the exemplary embodiment, the housing B27 of the exhaust aftertreatment device B26 is approximately cylindrical, and the outlet openings B30 are arranged on a flat end face of the housing B27. The outlet openings B30 are evenly distributed in a circular area of ​​the housing B27, as shown in Figure B2. The exhaust aftertreatment device B26 has a central axis B51. The central axis B51 forms the axis of symmetry of the cylindrical housing B27. The circular area is arranged concentrically around the central axis B51 of the exhaust aftertreatment device B26.

[0232] As shown in Fig. B3, the housing B27 is composed of a first housing section B33 and a second housing section B34. In the exemplary embodiment, the first A 1-98002 / sta

[0233] (PA21548WO)

[0234] 37

[0235] Housing section B33 is formed in multiple parts. In the exemplary embodiment, the second housing section B34 is formed in one piece. A one-piece design for the first housing section B33 and / or a multi-piece design for the second housing section B34 may also be advantageous. During the manufacture of the exhaust aftertreatment device B26, the housing sections B33 and B34 are movable relative to each other, at least temporarily, in a displacement direction B32, as will be described in more detail below.

[0236] In the exemplary embodiment, the first housing section B33 comprises an inlet shell B39, which is formed integrally with the partition B28. Alternatively, the inlet shell B39 can be formed separately from the partition B28 and fixed to the partition B28. As shown in Fig. B4, the inlet shell B39 comprises a plurality of inlet openings B29. The inlet openings B29 are arranged in a circular area concentric with the central axis B51, corresponding to the outlet openings B30.

[0237] In the exemplary embodiment, the first housing section B33 comprises an intermediate ring B41, which is fixed to the partition wall B28. For this purpose, the intermediate ring B41 has a flange B50 extending perpendicular to the central axis B51. As shown in Fig. B3, the flange B50 rests against the partition wall B28 and can be fixed to the partition wall B28, for example, by welding.

[0238] In the exemplary embodiment, the second housing section B34 is formed by an outlet shell B40. The outlet shell B40 overlaps the intermediate ring B41, as shown in Fig. B3.

[0239] As shown in the perspective exploded view in Fig. B4, a flow unit B31 is arranged in the housing B27 of the exhaust aftertreatment system B26. In the exemplary embodiment, the flow unit B31 is multi-part, namely two-part. A one-piece or multi-part design of the flow unit is also possible. A 1-98002 / sta

[0240] (PA21548WO)

[0241] 38

[0242] Flow unit B31 can be advantageous. Flow unit B31 is advantageously constructed of a compressible material that is essentially dimensionally stable during operation. Flow unit B31 is advantageously constructed of wire. In the exemplary embodiment, flow unit B31 has a first wire body B42 and a second wire body B43, as also shown in Fig. B5. Fig. B4 shows a clamping surface B35 formed on the inlet shell B39, against which flow unit B31 rests. The inlet openings B29 are arranged in the clamping surface B35. All inlet openings B29 are completely surrounded by areas of the clamping surface B35.

[0243] The outlet bowl B40 has a clamping surface B36 that completely surrounds all outlet openings B30 and is visible in Figs. B6 and B8.

[0244] As shown in Fig. B5, the inlet shell B39 has a base B52, a conical section B53 adjoining the base B52 circumferentially, and a cylindrical section B54 adjoining the conical section B53. In the exemplary embodiment, the base B52 is perpendicular to the central axis B51. The base B52 has the inlet openings B29. The conical section B53 and the cylindrical section B54 are rotationally symmetrical about the central axis B51.

[0245] The intermediate ring B41 has a cylindrical section B58 which is rotationally symmetrical about the central axis B51. In the exemplary embodiment, the flange B50 connects to the cylindrical section B58. The cylindrical section B58 of the intermediate flange B41 has an outer diameter i.

[0246] The flow unit B31 is essentially cylindrical and has a diameter g. The flow unit B31 has an inlet area B60, which in the exemplary embodiment is designed to rest against the clamping surface B35 and to be arranged at the inlet openings B29. With respect to a main flow direction B59 through the exhaust aftertreatment device B26, the inlet area forms A 1-98002 / sta

[0247] (PA21548WO)

[0248] 39 Flow surface B60 is the upstream side of the flow unit B31. With respect to the main flow direction B59, the flow unit B31 has an outlet surface B61 on its downstream side. The outlet surface B61 is designed to contact the second clamping surface B36 and the outlet openings B30, as shown in Fig. B6. The main flow direction B59 is directed from the inlet openings B29 to the outlet openings B30 and denotes the flow direction through the housing B27 that would result if no flow unit B31 were arranged in the housing B27. Due to the irregular shape of the openings in the flow unit B31, which are formed between the individual wire loops, the exhaust gases also flow in directions other than the main flow direction B59. As shown in Fig.As shown in B5, the flow unit B31 has a chamfer B62 adjacent to the inlet surface B60 and a chamfer B63 adjacent to the outlet surface B61.

[0249] The outlet shell B40 comprises a base B55, which is oriented perpendicular to the central axis B51. A conical section B56 adjoins the base B55, and a cylindrical section B57 adjoins this.

[0250] As shown in Fig. B6, the cylinder section B57 has an inner diameter h. The inner diameter h is, as shown in Fig. B6, larger than the outer diameter i of the intermediate flange B41. This allows the second housing section B34 to overlap the first housing section B33 at the intermediate flange B41, as shown in the sectional view in Fig. B6.

[0251] The intermediate ring B41 has an inner diameter e at its cylindrical section B58. The cylindrical section B54 of the inlet shell B39 has an inner diameter f. In the exemplary embodiment, the inner diameter e of the cylindrical section B58 of the intermediate ring B41 corresponds to the inner diameter f of the cylindrical section B54 of the inlet shell B39. The inner diameters e and f are larger than the outer diameter. A 1-98002 / sta

[0252] (PA21548WO)

[0253] 40 measure g of the flow unit B31, so that a free space B71 is formed adjacent to an outer circumference B65 of the flow unit B31.

[0254] The conical cut-offs B53 and B56 of the inlet shell B39 and outlet shell B40 form centering surfaces B44 and B45, respectively, on their inner surfaces. The central axis B51 lies parallel to a displacement direction B32, which is shown in Fig. B6. The centering surface B44 on the inlet shell B39 is inclined at an angle y to the displacement direction B32. The centering surface B45 on the outlet shell B40 is inclined at an angle 5 to the displacement direction B32. The angle y and the angle 5 are advantageously at least 10°, and particularly at least 20°.

[0255] Housing sections B33 and B34 (Fig. B5) are in contact with each other at the intermediate ring B41 and the cylindrical section B57 of the outlet shell B40. Housing sections B33 and B34 can be in direct contact with each other. Alternatively, they can be connected via a fastener, such as hardened weld molten metal, solder, or adhesive. The intermediate ring B41 forms a first contact surface B37 on its outer circumference. The outlet shell B40 forms a second contact surface B38 on the inner circumference of its cylindrical section B57. Housing sections B33 and B34 (Fig. B5) are in contact with each other at the contact surfaces B37 and B38. In this embodiment, the contact surfaces B37 and B38 are cylindrical and rotationally symmetrical about the central axis B51. In the displacement direction B32, which runs parallel to the central axis B51, the contact surfaces B37 and B38 are parallel to each other.This allows the housing sections B33 and B34 to be moved relative to each other in the displacement direction B32, as will be explained in more detail below.

[0256] The flow unit B31 is clamped in the housing B27 between the clamping surfaces B35 and B36. The preload under which the flow unit B31 is installed is advantageously selected to be large enough that the flow unit B31 A 1-98002 / sta

[0257] (PA21548WO)

[0258] 41 also remains fixed in the housing B27 between the clamping surfaces B35 and B36 during temperature development and vibrations during operation and cannot loosen.

[0259] In the exemplary embodiment, the first clamping surface B35 is perpendicular to the direction of displacement B32. The first clamping surface B35 forms an angle α with the direction of displacement B32, which is 90°. The second clamping surface B36 forms an angle β with the direction of displacement B32, 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°.

[0260] The flow unit B31 has a minimum thickness d, measured from the upstream end face B60 to the downstream end face B61, in a region of the flow unit B31 adjacent to the inlet openings B29 and the outlet openings B30. In the exemplary embodiment, the end faces B60 and B61 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 B31 where the end faces B60 and B61 are not flat and / or constant, the thickness is the minimum thickness in this region. The flow unit B31 may have a smaller thickness outside of regions adjacent to the inlet openings and the outlet openings B30. The minimum thickness d corresponds to the shortest path that exhaust gases can travel from an inlet opening B29 to an outlet opening B30 through the flow unit B31.The shortest path lies entirely within the flow unit B31.

[0261] The clamping surfaces B35 and B36 are arranged and designed such that each partial flow of an exhaust gas flow passing through the exhaust aftertreatment device B26 travels a path in the flow unit B31 that corresponds to at least B50% of the smallest thickness d of the flow unit B31 between the inlet opening B29 and the outlet opening B30. In the exemplary embodiment, the exhaust gas flow in Fig. B6 can enter at an external inlet opening B29 and A 1-98002 / sta

[0262] (PA21548WO)

[0263] 42. From there, the exhaust gas flows into the free space B71 formed between the flow unit B31 and the housing B26, thus creating a bypass flow to a section of the flow unit B31. From the free space B71, the exhaust gas can then flow back through the flow unit B31 to an external outlet opening B30. In the exemplary embodiment, the inlet openings B29 and the outlet openings B30 have a distance k from the outer circumference B65 of the flow unit B65. The distance k of the inlet opening B29 and the outlet opening B30 to the outer circumference B65 of the flow unit B31 is selected such that the exhaust gas flow in the flow unit B31 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 B31.

[0264] Fig. B7 shows an exemplary, partial view of the wire body B42. The wire body B42 can, for example, be made of knitted and crimped wire B64. The wire body B43 can be designed accordingly. Alternatively or additionally, at least one wire body B42, B43 of the flow unit B31 can be formed by individual pieces of wire or the like. The flow unit B31 is considered here to be the imaginary outer body that tightly encloses the at least one wire body B42, B43. The wire bodies B42 and B43 each comprise the wire B64 and openings B72 formed between the wire loops, through which exhaust gases can flow through the wire bodies B42 and B43. All dimensions of the flow unit B31 refer to this outer body. In the figures – with the exception of Fig. B7 – the outer body of the wire bodies B42 and B43 is shown.

[0265] The wire bodies B42 and / or B43 may be uncoated. Alternatively, at least one wire body B42 and / or B43 may have a washcoat coating. A washcoat is a coating that increases the surface area, in particular the wire surface area, without increasing the activation energy for the chemical reaction of A 1-98002 / sta

[0266] (PA21548WO)

[0267] 43

[0268] to reduce the emissions of exhaust gas or certain exhaust gas components. Additionally or alternatively, at least one wire body B42, B43 of the flow unit B31 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. A catalytic coating is, in particular, a coating containing a precious metal. A washcoat coating can be provided as a primer beneath a catalytic coating. Particularly preferably, the flow unit B31 has only a partial catalytic coating. This allows the manufacturing costs of the flow unit to be kept comparatively low. It is possible for both wire bodies B42 and B43 to have the same coating or for both wire bodies to have no coating at all.Alternatively, wire bodies B42 and B43 can have different coatings. For example, only one of wire bodies B42 or B43 can have a catalytic coating and / or only one of wire bodies B42 or B43 can have a washcoat coating. A combination with other wire bodies or other units that may be exposed to exhaust gas can also be advantageous.

[0269] Figures B8 and B9 show the exhaust aftertreatment device B26 during its manufacture. Figure B8 shows the exhaust aftertreatment device B26 in a process step in which the flow unit B31 has been positioned between the housing sections B33 and B34. In this position, the clamping surfaces B35 and B36 are spaced a distance a from each other. The distance a is significantly greater than the thickness c of the flow unit B31. Both the distance a and the thickness c are measured parallel to the central axis B51. The thickness c is measured from the inlet surface B60 to the outlet surface B61.

[0270] To clamp the flow unit B31 between the clamping surfaces B35 and B36, the housing sections B33 and B34 are moved towards each other in the displacement direction B32 so that the distance a between the clamping surfaces B35 A 1-98002 / sta

[0271] (PA21548WO)

[0272] 44 and B36 are reduced. It can be provided that the housing sections B33 and B34 are moved towards each other by a distance s, which is shown schematically in Fig. B8. The distance s is advantageously slightly larger than the difference between the distance a and the outlet thickness c of the flow unit B31. This compresses the flow unit B31 between the clamping surfaces B35 and B36 and clamps it firmly between them. The chamfers B62 and B63 of the flow unit B31 come into contact with the centering surfaces B44 and B45 of the housing B27 when the housing sections B33 and B34 are moved towards each other. Due to the contact of the chamfers B62 and B63 with the centering surfaces B44 and B45, the flow unit B31 is centered on the central axis B51.

[0273] It is possible that the flow unit B31, as shown in Fig. B6, has a small distance at its outer circumference from the housing B27 of the exhaust aftertreatment device B26. However, it is also possible that the flow unit B31 rests against the housing B27 at its outer circumference, as shown in Figures B8 and B9.

[0274] After the housing sections B33 and B34 are moved towards each other in the displacement direction B32, the clamping surfaces B35 and B36 have a distance b. The distance b corresponds at least to the initial thickness c of the flow unit B31. Preferably, the distance b is smaller than the initial thickness c.

[0275] Because the clamping surfaces B35 and B36 enclose angles α and β of 90° with the displacement direction B32, clamping of the flow unit B31 between the clamping surfaces B35 and B36 can be achieved during manufacturing even with small displacements of the housing sections B33 and B34 relative to each other in the displacement direction B32. 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 α between the clamping surfaces B35 and B36 can be achieved by displacing the housing sections B33 and B34 relative to each other. A 1-98002 / sta

[0276] (PA21548WO)

[0277] 45

[0278] It can be provided that the housing sections B33 and B34 are moved towards each other until a predetermined distance b between the clamping surfaces B35 and B36 is reached. Alternatively, it can be provided that the housing sections B33 and B34 are moved towards each other until a predetermined force for the displacement is reached. In the figures, the displacement direction B32 is shown as the displacement of the second housing section B34 relative to the first housing section B33. Only the relative movement of the housing sections B33 and B34 is relevant here, and not which housing section B33 and / or B34 actually moves.

[0279] In the embodiment shown in Figures B2 to B9, the centering surfaces B44 and B45 are truncated conical surfaces. After the housing sections B33 and B34 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 B32 is possible.

[0280] In the embodiment shown in Figures B2 to B9, the first housing section B33 includes a portion of the partition B28. Alternatively, the first housing section B33 can be movable relative to the partition B28 during manufacturing, and the second housing section B34 can include a portion of the partition B28.

[0281] Figures B10 to B15 show a further embodiment of an exhaust aftertreatment device B26. The same reference numerals denote corresponding elements in all figures. The exhaust aftertreatment device B26 of the second embodiment has an approximately cuboid housing B27. The housing B27 is formed by six pairs of opposing sides B46, B66, and B67. There are two opposing sides B46, two opposing sides B66, and two opposing sides B67. This results in an approximately cuboid shape for the housing A 1-98002 / sta

[0282] (PA21548WO)

[0283] 46

[0284] B26. The edges where sides B66 and B67 meet are formed by comparatively wide chamfers.

[0285] As shown in Fig. BIO, the housing B27 comprises a first housing section B33 and a second housing section B34. As shown in Figs. BIO and B1, the sides B46 of the housing B27 are each formed half on the first housing section B33 and half on the second housing section B34. The first housing section B33 is integrally formed with the partition B28 and encompasses a portion of the partition B28. The first housing section B33 forms an inlet shell B39. The second housing section B34 has a rim B73 by which the housing section B34 is fixed to the partition B28. The rim B73 runs parallel to the partition B28 and rests against it. The second housing section B34 forms an outlet shell B40. In the exemplary embodiment, the first housing section B33 and the second housing section B34 are each formed in one piece. A multi-part design of one or both housing sections B33 and B34 can also be advantageous.

[0286] The first housing section B33 has a contact surface B37 formed on the partition B28. The second housing section B34 has a contact surface B38, which in this embodiment is formed on the edge B73. The housing sections B33 and B34 are in contact with each other at the contact surfaces B37 and B38 and can be moved relative to each other in a displacement direction B32 that runs parallel to the partition B28. The contact surfaces B37 and B38 lie in a plane B68 that divides the opposite sides B46 of the housing B27. The plane B68, in which the contact surfaces B37 and B38 lie, passes through opposite edges B47 of the housing B27.

[0287] The sides B66 of the housing B27 form clamping surfaces B35 and B36 on their inner sides, as shown in Fig. Bl 1. A flow unit B31 is clamped between the clamping surfaces B35 and B36. If the second housing section B34 is moved in the displacement direction B32 relative to the first housing section B33, then A 1-98002 / sta

[0288] (PA21548WO)

[0289] 47. As the contact surfaces B37 and B38 (Fig. BIO) slide against each other, the distance between the contact surfaces B35 and B36 decreases to a desired dimension or until a desired force for displacement is reached. In Fig. B1, the distance b after the displacement and fixation of the housing sections B33 and B34 to each other is shown.

[0290] As shown in Fig. B1, the first contact surface B35 forms an angle α with the displacement direction B32 that is greater than 0°. 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 B36 forms an angle β with the displacement direction B32 and with the plane B68 that is greater than 0°, and preferably greater than 20°, and preferably greater than 30°. 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 B31.

[0291] As shown in Figures B12 to B14, the second housing section B34 has a plurality of outlet openings B30. The outlet openings B30 are formed in both side B66 and side B67 of the second housing section B34. The first housing section B33 has inlet openings B29. The inlet openings B29 are provided in sides B66 and B65 of the inlet shell B39 and are arranged and configured in a manner corresponding to the outlet openings B30. The inlet openings B29 are advantageously arranged and configured in a mirror-symmetrical manner with respect to plane B68 (Figure B11) relative to the outlet openings B40.

[0292] As shown in Fig. B12, the partition B28 has guides B69 on which the outlet dish B40 is mounted. The outlet dish B40 has receptacles B70 for this purpose. The guides B69 and the receptacles B70 run parallel to the direction of movement B32. A 1-98002 / sta

[0293] (PA21548WO)

[0294] 48

[0295] The exhaust aftertreatment device B21 shown in Figures B1 to B15 can be manufactured by moving the housing sections B33 and B34 relative to each other in the displacement direction B32 such that the distance b between the clamping surfaces B35 and B36 decreases until a desired distance b is reached or until a desired displacement force is achieved. Subsequently, the housing sections B33 and B34 are firmly joined together, for example by welding the rim B73 to the partition B28. This allows the desired clamping and preloading of the flow unit B31 between the clamping surfaces B35 and B36 to be achieved easily.

[0296] Further advantageous embodiments can result from any combination of the elements of the exemplary embodiments.

[0297] The invention further relates to an exhaust silencer of the type specified in the preamble of claim 22.

[0298] US Patent 5,612,006 A is known to be an exhaust silencer with a catalytic converter.

[0299] A sheet metal plate, wound spirally around the outer circumference of the catalytic converter, is arranged. The exhaust gases flow through a perforated plate at the front into the space formed between the turns of the spiral plate and from there out of the exhaust silencer.

[0300] The invention is based on the objective of creating an exhaust silencer of the generic type with a simple design, with which good exhaust emission values ​​can be achieved.

[0301] This problem is solved by an exhaust silencer with the features of claim 1. A 1-98002 / sta

[0302] (PA21548WO)

[0303] 49

[0304] The exhaust silencer comprises a coated flow element. Downstream of the flow element, an exhaust guide is arranged within the silencer housing. In internal combustion engines, particularly premixed-lubricated engines, particles can be present in the exhaust gas. In premixed-lubricated engines, these particles originate predominantly from the oil mixed with the fuel. To reduce the number and size of the particles, a sufficiently long residence time of the particles in a sufficiently high temperature is advantageous. Here, the particles can be broken down and / or partially combusted.

[0305] In exhaust silencers, heat is generated, particularly in a coated flow-through element. To utilize this heat for further exhaust gas conversion, especially for reducing particulate matter, the exhaust guide device is designed to include a first flow-through chamber and a second flow-through chamber. The first flow-through chamber extends at least partially around the outer circumference of the flow-through element. The second flow-through chamber extends at least partially around the outer circumference of the first flow-through chamber within the same silencer section. The second flow-through chamber is located downstream of the first flow-through chamber.

[0306] The flow chambers are arranged around the outer circumference of the flow body, with the downstream second flow chamber extending along the outer circumference of the first flow chamber. This creates a nested arrangement of the flow chambers. As a result, the exhaust gases can be heated by the flow body and, due to the arrangement of at least two flow chambers, retained in the hot zone of the exhaust silencer for a comparatively long time. A 1-98002 / sta

[0307] (PA21548WO)

[0308] 50

[0309] The fact that the second flow chamber is located downstream of the first flow chamber means that exhaust gases must first flow through the first flow chamber before they can enter the second flow chamber.

[0310] The first flow chamber extends at least partially around the outer circumference of the flow body. In particular, the first flow chamber extends over at least 80% of the outer circumference of the flow body. In particular, the second flow chamber extends completely around the outer circumference of the first flow chamber. In particular, the second flow chamber extends completely around the outer circumference of the first flow chamber. In particular, the second flow chamber forms a closed ring around the outer circumference of the first flow chamber.

[0311] The first flow space extends in the silencer section, in particular from one plane to the other that bounds the silencer section.

[0312] In particular, a first transfer zone is formed at a downstream end face of the first flow chamber, through which exhaust gases from the first flow chamber can pass into the second flow chamber. The flow chambers are directly connected to each other via the transfer zone. This allows for a compact design and enables the exhaust gas temperature to be maintained at a comparatively high level.

[0313] In particular, the exhaust gas guide includes a third flow chamber. This third flow chamber extends at least partially around the outer circumference of the second flow chamber within the silencer section and is located downstream of the second flow chamber. The third flow chamber further increases the residence time of the exhaust gases in the area of ​​the outer circumference of the flow chamber. The third flow chamber prevents rapid heat dissipation from the exhaust gases to the environment and thus forms a thermal insulation layer. A 1-98002 / sta

[0314] (PA21548WO)

[0315] 51. The third flow chamber extends around the first and second flow chambers. In particular, the third flow chamber extends over at least 80% of the outer circumference of the second flow chamber. Specifically, the third flow chamber extends completely around the outer circumference of the second flow chamber. In the silencer section, the third flow chamber extends in a ring-shaped manner around the outer circumference of the second flow chamber.

[0316] The first flow chamber, the second flow chamber, and the third flow chamber extend, in particular, within the same region of the outer circumference of the flow body. The first flow chamber, the second flow chamber, and the third flow chamber are, in particular, nested within one another.

[0317] A simple design results when at least one flow chamber is at least partially bounded by a pipe section. This pipe section runs completely around the flow body. The pipe section is a longitudinal segment of a pipe that is closed on its circumference. The cross-sectional shape of the pipe can be arbitrary and can be selected to suit the dimensions of the exhaust silencer.

[0318] At least one flow chamber is bounded by two pipe sections. One pipe section bounds the flow chamber, particularly on the inner side facing the flow body, and the other pipe section bounds the flow chamber, particularly on the outer side furthest from the flow body. This results in a simple design for the exhaust silencer.

[0319] An advantageous design results if the exhaust gas guide device is designed such that the exhaust gas lies on at least one pipe section on the inside facing the flow body and on a side facing away from the flow body. A 1-98002 / sta

[0320] (PA21548WO)

[0321] The flow direction is 52 degrees on the outside in opposite directions to the main flow direction. This counter-current flow direction allows for a simple design and good heat transfer through the pipe section.

[0322] A simple exhaust silencer design is achieved when at least two pipe sections, defining a flow space, are connected to the silencer housing at opposite ends. Connecting the pipe sections to the silencer housing at opposite ends allows for easy installation, as each pipe section can be fixed to a housing shell of the silencer at one end. Once all pipe sections are fixed, the two housing shells can be slid together, forming the exhaust guide.

[0323] In particular, the flow chamber has a partition wall that separates a first silencer chamber from a second silencer chamber. Specifically, the flow body and at least one pipe section are held against the partition wall. Specifically, the second pipe section is also held against the partition wall.

[0324] An advantageous design results when the silencer housing comprises a first housing shell and a second housing shell. The first housing shell, in particular, has the exhaust gas inlet. Specifically, at least one pipe section is held to the second housing shell. A simpler design results when a first pipe section is held to one of the housing shells and a second pipe section is held to the other housing shell. Specifically, the first pipe section and a third pipe section are held to the second housing shell.

[0325] In particular, at least one pipe section lacks a catalytically active coating. This at least one pipe section serves solely to conduct the exhaust gas flow, but not for catalytic conversion. The conversion of the Ab- A 1-98002 / sta

[0326] (PA21548WO)

[0327] The presence of gases in the exhaust gas ducting system is primarily due to the temperature and residence time in this area. In particular, all pipe sections lack a catalytically effective coating.

[0328] To prevent the heat from the flow element from radiating to components located at the inlet of the exhaust silencer, particularly an internal combustion engine, a shielding device is arranged upstream of the flow element. The shielding device is specifically designed to ensure direct radiative contact between the flow element and adjacent components, such as an exhaust port or piston assembly of an internal combustion engine. This prevents excessive heating of the internal combustion engine during operation with the exhaust silencer.

[0329] Advantageously, the exhaust silencer features a restrictor upstream of the exhaust outlet. This restrictor serves to adjust the desired exhaust backpressure within the silencer, ensuring a sufficiently long residence time for the exhaust gases. This allows for simple and effective particle conversion within the exhaust system. A simpler design is achieved when the restrictor is integrated into the second housing shell.

[0330] In particular, the flow body is coated with a catalytically active coating and / or a washcoat. This ensures efficient exhaust gas conversion within the flow body. Due to the catalytically active coating and / or the washcoat, high temperatures are achieved within the flow body, which can be utilized in the exhaust gas ducting system to further maintain the exhaust gases at a high temperature. A 1-98002 / sta

[0331] (PA21548WO)

[0332] 54

[0333] In particular, the elements limiting the flow spaces, especially the pipe sections, are not coated with a catalytically effective coating and not with washcoat.

[0334] Exemplary embodiments of the invention are explained below with reference to the drawing. The drawing shows:

[0335] Fig. CI a schematic sectional view of a chainsaw,

[0336] Fig. C2 is a perspective view of the exhaust silencer of the

[0337] Chainsaw from Fig. CI,

[0338] Fig. C3 shows a sectional view of the exhaust silencer,

[0339] Fig. C4 shows a section along line IV-IV in Fig. C3,

[0340] Fig. C5 is a cutaway perspective exploded view of the exhaust silencer,

[0341] Fig. C6 is a perspective exploded view of the exhaust silencer,

[0342] Fig. C7 shows another cutaway perspective exploded view of the exhaust silencer,

[0343] Fig. C8 shows a perspective exploded view of the exhaust silencer,

[0344] Fig. C9 shows a sectional view of an embodiment of the exhaust silencer, A 1-98002 / sta

[0345] (PA21548WO)

[0346] 55

[0347] Fig. CIO is a cutaway perspective exploded view of the exhaust silencer from Fig. C9,

[0348] Fig. Cl l is an exploded view of parts of the exhaust silencer from Figs. C9 and C10.

[0349] Fig. C12 is a cutaway exploded view of the parts from Fig. Cl l.

[0350] In figures CI to C12, the reference symbols mentioned below are shown without the leading letter C.

[0351] Fig. CI shows a chainsaw C101 as an example of a handheld power tool. Instead of the chainsaw C101, the handheld power tool could also be another tool such as an angle grinder, a cutter, a lawnmower, or the like. The handheld power tool is, in particular, a tool carried by the operator during operation.

[0352] The chainsaw C101 has a housing CI 02, which includes a rear handle CI 03. Operating elements, in this exemplary embodiment a throttle lever CI 04 and a throttle lever lock CI 05, are arranged on the rear handle CI 03. A guide bar CI 06 projects from the housing CI 02, on which a saw chain CI 07 (shown schematically) is arranged circumferentially. The saw chain CI 07 is driven by a drive motor located in the housing CI 02, in this exemplary embodiment an internal combustion engine, namely a two-stroke engine CI 08. Instead of the two-stroke engine CI 08, another internal combustion engine, in particular a four-stroke engine with mixture lubrication, can also be provided.

[0353] The two-stroke engine CI 08 includes an air filter CI 09, through which air is drawn in during operation. Fuel is supplied by a fuel supply device CI 10, see A 1-98002 / sta

[0354] (PA21548WO)

[0355] 56, for example, a carburetor. A mixture of fuel and two-stroke oil is supplied to the two-stroke engine CI 08 via the fuel supply device CI 10.

[0356] The two-stroke engine CI 08 has an intake port Cl 11 through which air is drawn from the air filter CI 09 into a crankcase CI 15 of the two-stroke engine CI 08. In this embodiment, the fuel supply device CI 10 feeds the fuel into the intake port Cl 11. However, the fuel supply can be located elsewhere, for example, in the crankcase CI 15.

[0357] The two-stroke engine CI 08 has a cylinder CI 12 in which a piston CI 13 is mounted to reciprocate. The piston defines a combustion chamber CI 14 formed within the cylinder CI 12. The piston CI 13 drives a crankshaft CI 17, which is rotatably mounted in the crankcase CI 15 about a pivot axis CI 18, via a connecting rod CI 16. The interior of the crankcase CI 15 is fluidically connected to the combustion chamber CI 14, at least in the region of the piston CI 13's bottom dead center, via transfer ports CI 19. A spark plug C120 protrudes into the combustion chamber CI 14. An exhaust port C121 leads from the combustion chamber CI 14. The exhaust port C121 is connected via an exhaust channel C122 to an exhaust inlet CI 24 of an exhaust silencer CI 23. The exhaust silencer C123 has an exhaust outlet C125 through which exhaust gases escape into the environment.

[0358] During operation, the two-stroke engine CI 08 draws a fuel / oil / air mixture into the crankcase CI 15 during the upward stroke of the piston CI 05. During the downward stroke of the piston CI 13, the mixture in the crankcase CI 15 is compressed. As soon as the transfer ports CI 19 open to the combustion chamber CI 14 during the downward stroke of the piston CI 13, the mixture flows from the crankcase CI 15 into the combustion chamber CI 14. During the upward stroke of the piston CI 13, the mixture is compressed in the combustion chamber CI 14 and ignited by the spark plug C120 near the top dead center of the piston CI 13. The subsequent combustion of the mixture accelerates the piston CI 13 towards the crankcase CI 15. As soon as the exhaust port C121 A 1-98002 / sta

[0359] (PA21548WO)

[0360] When piston Cl 13 opens at 57, the exhaust gases from combustion chamber CI 14 flow into the exhaust silencer CI 23. Fresh fuel / oil / air mixture then flows into combustion chamber CI 14 via the transfer ports CI 19 for the next engine cycle.

[0361] The CI 08 two-stroke engine can also be a scavenging-type two-stroke engine, in which air is pre-injected in the CI 19 transfer ports. This air assists in scavenging the exhaust gases from the previous engine cycle and separates the incoming fresh mixture from the exhaust gases. The CI 08 two-stroke engine can also be a premixed-lubricated four-stroke engine.

[0362] Particles are produced during the combustion of the fuel / oil / air mixture. These particles are intended to be reduced in the CI 23 exhaust silencer.

[0363] Fig. C2 shows an embodiment of the exhaust silencer C123 in a perspective view. The exhaust silencer C123 has a silencer housing C126. In this embodiment, the silencer housing C126 is constructed from two housing shells, namely a first housing shell CI 27 and a second housing shell CI 28. A different construction of the silencer housing CI 26 may also be advantageous. The two housing shells CI 27 and CI 28 are connected to each other at a circumferential rim C130. In this embodiment, fastening screws CI 72 are provided for connecting the housing shells CI 27 and C128. It is also possible for the housing shells CI 27 and C128 to be crimped at the rim CI 30 and thus connected to each other.

[0364] As shown in Fig. C2, the exhaust outlet C125 is formed on an outlet plate C129, which is held on the second housing shell C128. In the exemplary embodiment, the exhaust outlet C125 is formed by several openings in the outlet plate C129. A 1-98002 / sta

[0365] (PA21548WO)

[0366] 58

[0367] Figures C3 and C4 show the detailed construction of the exhaust silencer C123. Figure C3 shows a section through exhaust inlet CI 24 and exhaust outlet CI 25.

[0368] A flow-through element C131 is arranged in the silencer housing C126. The flow-through element C131 can, for example, be a body made of pressed metal wire, such as a metal mesh. The flow-through element C131 can also consist of coiled flat and corrugated sheets that form a multitude of passage channels through the flow-through element C131 between them.

[0369] The flow body C131 is coated. Specifically, the flow body C131 is coated with a washcoat and / or a catalytically active coating. A catalytically active coating, in this context, is defined as a coating that acts as a catalyst, thus lowering the activation energy for the chemical reaction of the exhaust gases and thereby increasing the reaction rate. A washcoat is not considered a catalytic coating in this context. A washcoat is defined as a coating that increases the surface area without lowering the activation energy for the chemical reaction. The flow body C131 can be coated with only a washcoat, only a catalytically active coating, or with both a washcoat and a catalytically active coating. Due to the coating of the flow body C131, efficient exhaust gas conversion is achieved within the flow body C131.The flow body C131 heats up considerably during operation.

[0370] The flow body C131 has an inlet area CI 78 through which the exhaust gases enter the flow body C131. The flow body C131 has an outlet area CI 79 through which the exhaust gases exit the flow body C131.

[0371] In the exemplary embodiment, the flow body C131 has an approximately cylindrical shape. Another shape for the flow body C131 can also be advantageous (A 1-98002 / sta).

[0372] (PA21548WO)

[0373] 59. The flow body C131 has a longitudinal direction C137. The longitudinal direction CI 37 runs parallel to a main flow direction CI 80 through the flow body C131. The main flow direction CI 80 through the flow body C131 runs, in particular, in a direction from the inlet surface CI 78 to the outlet surface CI 79. The main flow direction CI 80 runs, in particular, perpendicular to the inlet surface C178. However, another orientation of the main flow direction CI 80 may also be advantageous. The longitudinal direction CI 37 runs, in particular, parallel to a longitudinal center axis of the flow body C131.

[0374] The flow body C131 has a length a. The length a is measured in the main flow direction CI 80 from the inlet surface CI 78 to the outlet surface CI 79. With an irregular surface structure of the flow body C131, the inlet surface CI 78 and the outlet surface CI 79 are surfaces of a surrounding body.

[0375] The flow body C131 is surrounded on its outer circumference by several flow chambers C138, C139, C140, and C141. In the exemplary embodiment, the flow chambers C138 to C141 extend completely around the flow body C131. The flow chambers C138 to C141 are arranged one after the other with respect to the direction of exhaust gas flow through the exhaust silencer CI 23. In particular, exhaust gases cannot enter a flow chamber located downstream of another flow chamber without first flowing through that other flow chamber. This means, for example, that for the second flow chamber CI 39 located downstream of the first flow chamber C138, exhaust gases must first flow through the flow chamber C138 in order to be able to enter the second flow chamber CI 39 located downstream of it.

[0376] The flow-through body C131 is held in a partition CI 32 of the exhaust silencer C123. The partition C132 separates a first silencer chamber A 1-98002 / sta

[0377] (PA21548WO)

[0378] 60

[0379] C133 from a second silencer chamber C134. In the exemplary embodiment, the flow passages C138 to C141 are arranged in the second silencer chamber C134. In the exemplary embodiment, the exhaust gas inlet C124 opens into the first silencer chamber C133.

[0380] In the exemplary embodiment, a shielding device C151 is arranged between the inlet surface CI 78 and the exhaust gas inlet C124, which will be explained in more detail below. A throttle C135 leads from the second silencer chamber CI 34. Exhaust gases from the second housing shell CI 28 pass through the throttle C135 into an area covered by the outlet plate C129 and from there through the exhaust gas inlet CI 24 into the environment.

[0381] The flow chambers C138 to C141 are formed in an exhaust gas guide device CI 36, which is arranged downstream of the flow body C131. The throttle C135 serves to set a suitable exhaust gas back pressure in order to achieve a desired residence time of the exhaust gases in the exhaust gas guide device C136.

[0382] In the exemplary embodiment, the exhaust gases from the flow body C131 pass directly into the first flow chamber C138. The first flow chamber C138 is connected to the second flow chamber C139 via a transition area C142. The second flow chamber C139 is connected to the third flow chamber C140 via a transition area C143. The third flow chamber C140 is connected to the fourth flow chamber C141 via a transition area C144. From the fourth flow chamber C141, the exhaust gases pass to the throttle C135.

[0383] The transition area C142 is formed at a downstream end face C153 of the first flow chamber C138. The transition area C143 is formed at a downstream end face C154 of the second flow chamber C139. The transition area C144 is formed at a downstream end face C155 of the third flow chamber. A 1-98002 / sta

[0384] (PA21548WO)

[0385] 61

[0386] Flow chamber Cl 40 is formed. Through the transition areas C142, C143, C144, exhaust gases from a flow chamber C138, C139, C140 pass into the flow chamber CI 39, CI 40, C141 arranged downstream.

[0387] In the exemplary embodiment, the flow chambers C138 to C141 are nested within each other. In this embodiment, the flow chambers C138 to C141 surround the flow body C131 as annular spaces running around each other.

[0388] In the exemplary embodiment, the flow chambers C138 to C141 are bounded by pipe sections C148, C149 and C150. The pipe sections C148, C149 and C150 are nested within each other.

[0389] The first flow chamber C138 is formed between an outer circumference C171 of the flow body C131 and an inner surface C158 of the first pipe section C148. The first transition area CI 42 extends along an open end face C168 of the first pipe section C148. The exhaust gases flow in the first flow chamber C138 in a main flow direction CI 64. In the exemplary embodiment, the main flow direction CI 64 is opposite to the main flow direction CI 80 in the flow body C131.

[0390] The second flow chamber CI 39 extends along an outer circumference CI 45 of the first flow chamber C138. As shown in Fig. C4, the second flow chamber C139 is bounded by an outer surface C159 of the first pipe section C148 and an inner surface C160 of the second pipe section C149. As shown in Fig. C3, a main flow direction CI 65 in the second flow chamber CI 39 runs approximately parallel to the main flow direction CI 80 in the flow body C131. The main flow directions CI 64 and CI 65 are opposite to each other.

[0391] The second transition area CI 43 extends along an open end face CI 69 of the second pipe section C149. The third flow chamber C140 is enclosed by an A 1-98002 / sta

[0392] (PA21548WO)

[0393] 62

[0394] The outer surface C161 of the second pipe section CI 49 and an inner surface CI 62 of the third pipe section CI 50 are bounded, as shown in Fig. C4. A main flow direction C166 in the third flow chamber C140 runs, as shown in Fig. C3, opposite to the main flow direction CI 80 in the flow body C131.

[0395] The third transition area C144 is formed at an end face C170 of the third pipe section C150. The fourth flow chamber C141 runs along an outer side C163 of the third pipe section C150. In the exemplary embodiment, the fourth flow chamber C141 is bounded by the partition CI 32, the third pipe section CI 50, and the second housing shell C128. A main flow direction CI 67 in the fourth flow chamber C141 runs, as shown in Fig. C3, parallel to the main flow direction CI 80 in the flow body C131.

[0396] In the exemplary embodiment, the third pipe section CI 50 is formed on a pot-shaped sheet metal part. The bottom CI 87 of the pot delimits the area of ​​the first flow chamber C138 adjacent to the outlet surface C179.

[0397] The third flow chamber CI 40 extends along the outer circumference CI 46 of the second flow chamber C139. The fourth flow chamber C141 extends at least partially along the outer circumference C147 of the third flow chamber C140. In the exemplary embodiment, the outer flow chambers CI 39, CI 40, and C141 each extend completely around the outer circumference of the inner flow chambers C138, C139, and C140.

[0398] The first flow passage C138 extends completely around the outer circumference C171 of the flow body C131. However, it is also possible for the flow passages C138 to C141 to be interrupted in the circumferential direction. This can be particularly advantageous for reasons of space. A 1-98002 / sta

[0399] (PA21548WO)

[0400] 63

[0401] In this embodiment, the term "pipe section" means a continuous, closed wall. The cross-sectional shape can be largely arbitrary. In particular, a round or rounded rectangular cross-sectional shape can be provided for one or more pipe sections C148 to C150. Specifically, the cross-sectional shape is irregular and adapted to the available installation space. The pipe sections C148, C149, and C150 each run completely around the flow body C131. The pipe sections C148, C149, and C150 are designed as circumferentially closed tubes.

[0402] In this embodiment, the first flow chamber C138 does not extend over the entire length a of the flow body C131 at its outer circumference C171, but rather over a length b of a silencer section CI 52. The silencer section CI 52 extends from a first imaginary plane CI 56 to a second imaginary plane CI 57. The planes CI 56 and CI 57 are parallel to each other and perpendicular to the longitudinal direction C137 of the flow body C131. In this embodiment, the first plane CI 56 lies between the inlet surface CI 78 and the outlet surface CI 79. The second plane CI 57 coincides with the outlet surface CI 79 in this embodiment. Other positions of the planes CI 56 and CI 57 may also be advantageous. The planes CI 56 and CI 57 are spaced apart by a distance corresponding to the length b of the silencer section CI 52.The length b is in particular at least 20%, in particular at least 50%, in particular at least 75% of the length a of the flow body C131.

[0403] In the first level CI 56, in particular, lies an end face of a pipe section, specifically an end face C168 of the first pipe section C148. The end face C168 forms a free end of the pipe section C148. At an opposite end face C188, the first pipe section C148 is fixed to the base C187 of the pot that forms the third pipe section CI 50. The fixing is effected in particular by a welded connection. A 1-98002 / sta

[0404] (PA21548WO)

[0405] 64

[0406] In the silencer section Cl 52, the first flow chamber C138, the second flow chamber CI 39, the third flow chamber CI 40, and the fourth flow chamber C141 extend in at least one section plane containing the longitudinal direction CI 37. Such a section plane is, for example, the section plane in Fig. C3. The flow chambers C138, C139, C140, and C141 extend continuously from the first level CI 56 to the second level CI 57. Specifically, the flow chambers C138, C139, C140, and C141 extend completely around the longitudinal direction C137 continuously from the first level CI 56 to the second level CI 57.

[0407] Figures C5 and C6 show the construction of the exhaust silencer C123. The first housing shell C127 and a stiffening plate CI 92 fixed to the first housing shell C127 form a first assembly of the exhaust silencer CI 23. A second assembly is formed by the partition CI 32 with the flow element C131 arranged in the partition CI 32. The partition C132 has a mounting area to which the second pipe section C149 is fixed.

[0408] A third assembly comprises the second housing shell CI 28 and the pipe sections C148 and C150. Pipe section C148 is fixed at its end face C188 to the base C187 formed on pipe section C150. Pipe section C149 is fixed at its end face CI 89 to the partition CI 32. The base CI 87 connects to the end face CI 90 of pipe section CI 50. The end faces CI 68, CI 69, and CI 70 of the pipe sections are exposed and do not touch any other components.

[0409] The three assemblies are connected to each other via the fastening screws CI 72. Pipe section C149 has a fastening edge C173 on end face C189. Pipe section C148 has a fastening edge C174 on end face C188. Fastening studs C175 are arranged on the base C187. With the fastening A 1-98002 / sta

[0410] (PA21548WO)

[0411] 65 stutzen C175 is the pipe section C150 held on the second housing shell C128 at a distance to the second housing shell CI 28.

[0412] Figures C7 and C8 show the detailed design of the components. As shown in Figures C7 and C8, a seal CI 76 is arranged between the first housing shell C127 and the partition C132. Also shown in Figures C7 and C8 is the shielding device CI 51, which has outwardly projecting mounting arms CI 77. These mounting arms are designed for fixing the shielding device to the partition CI 32.

[0413] Figures C9 to C12 show an alternative embodiment of an exhaust silencer C123. The design of the exhaust silencer C123 corresponds, except for the design of the shielding device C181, to the design of the preceding embodiment, to whose description reference is made. In Figures C9 to C12, a shielding device C181 is arranged between the exhaust inlet C124 and the inlet surface CI 78 of the flow body C131, and is constructed from two sheets. The sheets are spaced apart from each other by a distance d measured parallel to the longitudinal axis C137. Due to the distance d between the two sheets CI 82 and CI 83, the shielding device CI 81 requires more installation space than the shielding device C151.

[0414] As shown in Figures C11, C12, and C13, the shielding device C181 comprises a first sheet C182 and a second sheet C183, each with openings C184. The openings CI84 of the two sheets CI82 and CI83 are not aligned with each other when viewed from the exhaust gas inlet C124 to the flow body C131. The openings CI84 are offset from each other. This ensures that the inlet area CI78 is covered by the shielding device CI81.

[0415] As shown in Figures C1 and C12, the first sheet C182 has fastening arms CI 85. The second sheet CI 83 has fastening arms CI 86. Both sheets A 1-98002 / sta

[0416] (PA21548WO)

[0417] 66

[0418] Cl 82, Cl 83 are fixed to the partition CI 32 with the mounting arms Cl 85 and Cl 86.

[0419] In both embodiments, the shielding devices C151, C181 have a distance c from the inlet area CI 78 of the flow body C131, as shown in Figures C3 and C9. The distance c is dimensioned to be sufficiently large, in particular, to ensure that the flow body C131 is uniformly supplied with exhaust gas.

[0420] In the illustrated embodiments, the flow chambers C138 to C141 are arranged approximately cylindrically around the flow body C131. The pipe sections C148, C149 and C150 are not connected to each other within the silencer section C152, but rather outside the silencer section C152, in particular via the partition C132 and the housing shell C128.

[0421] In an alternative embodiment, not shown, the flow chambers can be formed in pipes wound spirally around the flow body. A first flow chamber, spiraling around the flow body C131, extends particularly directly along the outer circumference C171 of the flow body C131. A second pipe section, arranged downstream of the first pipe section, extends radially outside the first pipe section with respect to the longitudinal direction C137. The second pipe section is particularly spirally wound around the first pipe section. The first pipe section forms a first flow chamber, and the second pipe section forms a second flow chamber, extending around the outer circumference of the first flow chamber. Further flow chambers can also be formed in a corresponding manner.

[0422] The shielding devices CI 51 and CI 81 form radiation barriers between the two-stroke engine and the flow chamber C131. Due to the several flow chambers C138, C139, CI 40, C141 arranged in series, the following results for A 1-98002 / sta

[0423] (PA21548WO)

[0424] 67 The exhaust gases in the exhaust gas guide device Cl 36 have a very long flow path. Due to the arrangement on the outer circumference of the flow body C131, high exhaust gas temperatures can be achieved in the exhaust gas guide device C136. Due to the high temperature and the long residence time of the exhaust gases resulting from the long flow path, good particle conversion can be achieved in the exhaust gas guide device CI 36.

[0425] Because pipe sections C148 to C150 are not connected to each other in the silencer section C152, there is no direct heat conduction between the pipe sections. In particular, at least one flow-through chamber C138, C139, C140, C141 is a free, unfilled space. In particular, all flow-through chambers C138, C139, C140, C141 are free, unfilled spaces.

[0426] In particular, the individual parts of the exhaust silencer CI 23 are connected to each other via spot welds. This ensures minimal heat transfer between the individual elements. Because the transition areas C142, C143, and C144 are located in the region of end faces C168, C169, and C170 of the pipe sections C148, C149, and C150, the free flow cross-section of the transition areas C142 to C144 can be easily adjusted by selecting a suitable position for the end faces CI 68, CI 69, and CI 70. This allows for simple structural adaptation of the exhaust silencer C123 to specific requirements without fundamentally altering its geometry.

Claims

A 1-98002 / sta (PA21548WO) 68 Claims 1. Exhaust aftertreatment device, wherein the exhaust aftertreatment device (A32) comprises a flow unit (A33) which is held in a housing (A34) of the exhaust aftertreatment device (A32), wherein the flow unit (A33) comprises at least one wire body (A36, A40), wherein the wire body (A36, A40) has at least one first region (A37, A41) with a first mean density and at least one second region (A38, A42) with a second mean density, characterized in that the second mean density is at least 1.5 times the first mean density and that the wire body (A36, A40) is clamped at the second region (A38, A42) between at least two clamping sections (A46, A47) of the housing (A34).

2. Exhaust aftertreatment device according to claim 1, characterized in that the wire body (A36, A40) is held clamped between the clamping sections (A46, A47) in a clamping direction (A62), wherein the clamping direction (A62) has at least one directional component that runs perpendicular to an inlet surface (A44) of the flow unit (A33) and / or parallel to a main flow direction (A35) through the flow unit (A33), wherein the clamping direction (A62) is in particular perpendicular to the inlet surface (A44) and / or parallel to the main flow direction (A35).

3. Exhaust aftertreatment device according to claim 1 or 2, characterized in that the second mean density is at least twice, in particular at least three times, the first mean density.

4. Exhaust aftertreatment device according to one of claims 1 to 3, characterized in that the second area (A38, A42) is located outside a A 1-98002 / sta (PA21548WO) 69 flow area (A48) of the exhaust aftertreatment system (A32) is located.

5. Exhaust aftertreatment device according to one of claims 1 to 4, characterized in that an area of ​​at least one, in particular each clamping section (A46, A47) is at least 5%, in particular at least 10% of an area of ​​the flow area (A48) measured when looking perpendicularly at an inlet area (A44).

6. Exhaust aftertreatment device according to one of claims 1 to 5, characterized in that the inlet area (A44) of the flow unit (A33) is an imaginary flat surface which abuts the flow unit (A33), wherein the flow unit (A33) in particular has an outlet area (A45), wherein the outlet area (A45) is an imaginary flat surface, wherein the inlet area (A44) and / or the outlet area (A45) in particular abut the flow unit (A33), wherein the flow unit (A33) in particular lies between imaginary flat surfaces which abut the inlet area (A44) and the outlet area (A45).

7. Exhaust aftertreatment device according to claim 6, characterized in that a maximum extent (Ab) of the second region (A38, A42) measured perpendicular to the inlet surface (A44) is smaller than a maximum extent (Aa) of the first region (A37, A41) measured perpendicular to the inlet surface (A44).

8. Exhaust aftertreatment device according to claim 6 or 7, characterized in that the second area (A38, A42) extends around the first area (A37, A41) when viewed perpendicular to the inlet surface (A44). A 1-98002 / sta (PA21548WO) 70 9. Exhaust aftertreatment device according to one of claims 6 to 8, characterized in that the flow unit (A33) has an upstream end face (A49) against which the inlet surface (A44) abuts, that the flow unit (A33) has a downstream end face (A50) against which the outlet surface (A45) abuts, and that the housing (A34) abuts at least one of the end faces (A49, A50).

10. Exhaust aftertreatment device according to claim 9, characterized in that the housing (A34) has at least one inlet opening (A51) on the upstream end face (A49) and at least one outlet opening (A52) on the downstream end face (A50), and that the housing (A34) covers the upstream end face (A49) and / or the downstream end face (A50) perpendicularly to the respective end face (A49, A50) in the direction of view at an overlap area (A60) which extends along the edge of the end face (A49, A50) and whose width (h) is at least 0.5 mm.

11. Exhaust aftertreatment device (B26) with a housing (B27) and a flow unit (B31) arranged in the housing (B27), wherein the housing (B27) comprises a first housing section (B33) and a second housing section (B34), wherein the housing (B27) has at least one inlet opening (B29) and at least one outlet opening (B30), wherein all inlet openings (B29) are arranged in the first housing section (B33) and all outlet openings (B30) are arranged in the second housing section (B34), wherein the first housing section (B33) has a first contact surface (B37) and the second housing section (B34) has a second contact surface (B38), wherein the housing sections (B33, B34) are in contact with each other via their contact surfaces (B37, B38), characterized in that the flow unit (B31) is located between a A 1-98002 / sta (PA21548WO) 71 first clamping surface (B35) and a second clamping surface (B36) of the housing (B27) is clamped, wherein the first clamping surface (B35) is formed on the first housing section (B33) and wherein the second clamping surface (B36) is formed on the second housing section (B34) and that the first contact surface (B37) and the second contact surface (B38) run parallel to each other in the displacement direction (B32), which encloses a first angle (Ba) with the first clamping surface (B35) and a second angle (ß) with the second clamping surface (B36), wherein the first angle (a) and the second angle (ß) are each greater than 0°.

12. Exhaust aftertreatment device (B26) according to claim 11, characterized in that the first angle (a) and the second angle (ß) are at least 20°.

13. Exhaust aftertreatment device (B26) according to claim 11 or 12, characterized in that the clamping surfaces (B35, B36) are arranged and designed such that each partial flow of an exhaust gas flow passing through the exhaust aftertreatment device (B26) travels a path in the flow unit (B31) that corresponds to at least 50% of the smallest thickness (d) of the flow unit (B31) between the at least one inlet opening (B29) and the at least one outlet opening (B30).

14. Exhaust aftertreatment device (B26) according to one of claims 11 to 13, characterized in that the housing sections (B33, B34) are firmly connected to each other.

15. Exhaust aftertreatment device (B26) according to one of claims 11 to 14, characterized in that the flow unit (B31) is formed by at least one wire body (B42, B43). A 1-98002 / sta (PA21548WO) 72 16. Exhaust aftertreatment device (B26) according to one of claims 11 to 15, characterized in that the at least one inlet opening (B29) and / or the at least one outlet opening (B30) is surrounded by a centering surface (B44, B45) against which the flow unit (B31) rests and which is inclined to the displacement direction (B32) by an angle (y, 5) of at least 10°.

17. Exhaust aftertreatment device (B26) according to one of claims 11 to 16, characterized in that the housing (B27) is formed by at least six mutually opposite sides (B46) and a plane (B68) in which the contact surfaces (B37, B38) are located extends through two opposite sides (B46) of the housing (B27).

18. Exhaust silencer (B23) with an exhaust inlet (B24), an exhaust outlet (B25) and an exhaust aftertreatment device (B26) arranged in the flow path between the exhaust inlet (B24) and the exhaust outlet (B25) according to one of claims 11 to 17.

19. Method for manufacturing an exhaust aftertreatment device (B26) according to one of claims 11 to 17, characterized in that the two housing sections (B33, B34) of the housing (B27) are moved towards each other in the displacement direction (B32) such that the distance (a, b) between the clamping surfaces (B35, B36) is reduced, and the housing sections (B33, B34) are firmly connected to each other in a subsequent process step.

20. Method according to claim 19, characterized in that the housing sections (B33, B34) are moved towards each other until a predetermined distance (b) between the clamping surfaces (B35, B36) is reached. A 1-98002 / sta (PA21548WO) 73 21. Method according to claim 19, characterized in that the housing sections (B33, B34) are moved towards each other until a predetermined force for displacement is reached.

22. Exhaust silencer comprising a silencer housing (C126) with an exhaust inlet (CI 24) and an exhaust outlet (CI 25), with a coated flow element (CI 31) arranged in the flow path from the exhaust inlet (CI 24) to the exhaust outlet (CI 25), and with an exhaust guide device (C136) arranged downstream of the flow element (C131) in the silencer housing (C126), wherein the flow element (C131) has a longitudinal direction (C137) corresponding to a main flow direction through the flow element (C131), wherein the exhaust silencer (C123) has a silencer section (CI 52) extending between two imaginary planes (C156, C157) perpendicular to the longitudinal direction (C137) of the flow element (C131), and in which at least a part of the flow element (C131) extends, wherein the exhaust gas guide device (C136) comprises a first flow chamber (CI 38),which extends at least partially around the outer circumference (C171) of the flow body (CI 31) in the silencer section (C152), characterized in that the exhaust guide device (CI 36) comprises a second flow chamber (C139) which extends at least partially around the outer circumference (C145) of the first flow chamber (CI 38) in the silencer section (C152) and which is arranged downstream of the first flow chamber (CI 38).

23. Exhaust silencer according to claim 22, characterized in that a first transition area (C142) is formed on a downstream end face (CI 53) of the first flow space (C138). A 1-98002 / sta (PA21548WO) 74 is through which exhaust gases from the first flow chamber (CI 38) can pass into the second flow chamber (CI 39).

24. Exhaust silencer according to claim 22 or 23, characterized in that the exhaust guide device (CI 36) comprises a third flow chamber (C140) which extends at least partially around the outer circumference (C146) of the second flow chamber (CI 39) in the silencer section (C152) and which is arranged downstream of the second flow chamber (C139).

25. Exhaust silencer according to one of claims 22 to 23, characterized in that at least one flow space (CI 38, C139, C140) is at least partially bounded by a pipe section (C148, C149, C150) which runs completely around the flow body (C131).

26. Exhaust silencer according to claim 25, characterized in that at least one flow space (CI 39, C140) is bounded by two pipe sections (C148, C149, C150).

27. Exhaust silencer according to claim 25 or 26, characterized in that the exhaust guide device (CI 36) is designed such that the exhaust gas flows in opposite main flow directions (CI 64, CI 65, CI 66, CI 67) on at least one pipe section (C148, C149, CI 50) on an inner side (C158, C160, C162) facing the flow body (CI 31) and on an outer side (CI 59, C 161, CI 63) facing away from the flow body (C131).

28. Exhaust silencer according to one of claims 25 to 27, characterized in that at least two have a flow space A 1-98002 / sta (PA21548WO) 75 (C139, C140) limiting pipe sections (C148, C149, C150) are connected to the silencer housing (Cl 26) at different, opposite end faces (Cl 88, Cl 89, Cl 90).

29. Exhaust silencer according to one of claims 25 to 28, characterized in that the exhaust silencer (C123) has a partition (C132) that separates a first silencer chamber (C133) from a second silencer chamber (C134), wherein the flow body (C131) and at least one pipe section (C149) are held on the partition (C132).

30. Exhaust silencer according to claim 29, characterized in that the second pipe section (C149) is held on the partition (CI 32).

31. Exhaust silencer according to one of claims 25 to 30, characterized in that the silencer housing (C126) comprises a first housing shell (C127) and a second housing shell (C128), wherein the first housing shell (C127) has the exhaust inlet (C124) and wherein at least one pipe section (C148, C150) is held on the second housing shell (C128).

Images