EP4112892A1 - Sound absorber - Google Patents

Abstract

A muffler for an exhaust system of an internal combustion engine comprises a muffler housing with a peripheral wall that is elongated in the direction of a housing longitudinal axis (L) and at least one base wall (14) surrounded by the peripheral wall and/or held on the peripheral wall and delimiting a chamber in the muffler housing, wherein in at least a bottom wall (14), at least one bottom wall opening (36 ) is provided.

Description

The present invention relates to a muffler for an exhaust system of an internal combustion engine, for example in a motor vehicle.

Such an example from the EP 1 888 891 B2 A known muffler includes a muffler body having a peripheral wall and a plurality of bottom walls surrounded by and supported by the peripheral wall. In the two axial end regions of the peripheral wall, such base walls form respective end walls which close off the interior of the muffler housing in the direction of a longitudinal housing axis to the outside. In the area of the muffler housing lying between the two end walls, such bottom walls form respective intermediate walls which separate chambers formed inside the muffler housing from one another. Such chambers can communicate with one another through openings provided in a respective intermediate wall, but can also form a resonator chamber for a Helmholtz resonator.

In order to be able to guide an exhaust gas pipe, which can also provide a resonator neck for such a Helmholtz resonance, through such a bottom wall, it is known to form a passage surrounding a bottom wall opening and extending from a substantially flat area of a respective bottom wall into To form an opening edge region extending in the direction of an opening center axis of a respective bottom wall opening. This has a substantially cylindrical structure and accommodates an exhaust pipe. Such bottom wall openings surrounded by a respective opening edge region have an oversize with respect to an external dimension, i.e. for example the external diameter of an exhaust pipe constructed with a substantially circular cross-section, so that an exhaust pipe can be accommodated in such a bottom wall opening with little play and thus in an installation position provided for it can be brought. In this position, a respective exhaust pipe is then used for a fixed connection connected to the bottom wall traversed by this by material connection, generally by welding.

It is the object of the present invention to provide a muffler for an exhaust system of an internal combustion engine and a method for producing such a muffler, with which a noise-avoiding connection between a bottom wall and an exhaust pipe passing through it is obtained with a simplified structure.

According to a first aspect of the present invention, this object is achieved by a muffler for an exhaust system of an internal combustion engine, comprising a muffler housing with a peripheral wall that is elongated in the direction of a housing longitudinal axis and at least one chamber surrounded by the peripheral wall or/and held on the peripheral wall The bottom wall delimiting the muffler housing, at least one bottom wall opening being surrounded by an opening edge region bent essentially in the direction of the housing longitudinal axis on a substantially planar bottom wall region of the bottom wall and accommodating an exhaust pipe with a press fit.

In the muffler according to the invention, at least one exhaust pipe is held in an associated bottom wall opening by means of a press fit, which on the one hand achieves a stable connection and, on the other hand, due to the constant contact that is present and is under pressure or prestress, the occurrence of relative movements between the bottom wall and the exhaust pipe passing through it. which can lead to impact noises or rattling noises, is avoided. Further measures for providing a firm connection are not necessary in principle, although in addition to the holding by means of a press fit, a material connection, for example a connection by welding, can also be provided.

In particular, when in the area of the connection of a bottom wall to an exhaust pipe, for example, to provide a Helmholtz resonator If a gas-tight seal is to be achieved, it is advantageous if the opening edge region is designed to run completely around a central opening axis of the bottom wall opening in the circumferential direction.

In an alternative embodiment, the opening edge area can be designed to be interrupted in the circumferential direction around an opening center axis of the bottom wall opening. For example, this can be realized in that the opening edge area comprises a plurality of opening edge area segments arranged at a distance from one another in the circumferential direction around an opening center axis of the bottom wall opening.

In a configuration that can be implemented cost-effectively and is nonetheless resistant to high temperatures and aggressive components of exhaust gas from an internal combustion engine, the at least one bottom wall can be designed as a formed sheet metal part. It is advantageous if at least one bottom wall has a wall thickness of at most 1 mm, preferably at most 0.6 mm, particularly when the edge area of the opening is to be closed in the circumferential direction, for example in order to achieve a substantially gas-tight seal. In this case, the bottom wall is also sufficiently deformable in the area of the closed opening edge area to produce the press fit when the exhaust pipe is pushed or pressed into the bottom wall opening, also in the area of its elastic deformability, in order to be able to accommodate an exhaust pipe and generate a sufficiently strong contact pressure against its outer peripheral surface to be able to

The opening edge area can have a first edge section adjoining the substantially planar bottom wall area in a first bend area and a second edge section adjoining the first edge section in a second bend area, with a radial distance of the first edge section to an opening center axis of the bottom wall opening in the direction from the first bend area to the second Bending range preferably decreases substantially constantly. In the area of the second bending area then the area of the minimum distance of the opening edge area to the opening central axis can be provided.

A radial distance between the second edge section and the central axis of the opening can be essentially constant in the direction away from the second bending area, so that an essentially cylindrical area is formed in which there is a planar contact between the opening edge area and the exhaust gas pipe. A material connection, for example a welded connection, can also be produced on one end face of this cylindrical section between the bottom wall and the exhaust gas pipe.

In a configuration that supports, in particular, the easy pressing of the exhaust pipe into a base wall opening that accommodates it and avoids tilting when an exhaust pipe is pushed into a base wall opening, a radial distance of the second edge section with respect to the central axis of the opening can preferably increase substantially constantly in the direction away from the second bending area.

Furthermore, it can be provided that the opening edge area runs curved from a first axial end area of the opening edge area adjoining the essentially flat area of the bottom wall to an axial area of the opening edge area with a minimal distance to an opening center axis of the bottom wall opening.

If the opening edge area is curved from the area of the opening edge area with a minimum distance to the opening center axis of the bottom wall opening to a second axial end area of the opening edge area remote from the essentially flat area of the bottom wall, the entire opening edge area can be designed, for example, with an approximately constant radius of curvature in the axial direction Forming area of the bottom wall are provided.

The at least one bottom wall may be an intermediate wall separating two chambers in the muffler housing. Alternatively, the at least one bottom wall may be an end wall located at an axial end portion of the peripheral wall. It should be noted that, of course, in a muffler one or more intermediate walls as well as one or both end walls can be designed as a bottom wall with the construction described above. It should also be pointed out that one or more such bottom walls can also have a plurality of bottom wall openings, one or more or all of which can have the structure described above for accommodating a respective exhaust pipe with a press fit.

1. a) Bereitstellen wenigstens einer Bodenwand für ein Schalldämpfergehäuse derart, dass wenigstens eine in der Bodenwand ausgebildete Bodenwandöffnung von einem von einem im Wesentlichen ebenen Bodenwandbereich im Wesentlichen in Richtung einer Öffnungsmittenachse abgebogenen Öffnungsrandbereich derart umgeben ist, dass die Bodenwandöffnung eine vorbestimmte Innenabmessung, vorzugsweise Innendurchmesser, aufweist,
2. b) Bereitstellen eines in der von dem Öffnungsrandbereich umgebenen Bodenwandöffnung aufzunehmenden Abgasrohrs mit einer vorbestimmten Außenabmessung, vorzugsweise Außendurchmesser, wobei die vorbestimmte Außenabmessung des Abgasrohrs größer ist als die vorbestimmte Innenabmessung der Bodenwandöffnung,
3. c) Einführen des Abgasrohrs in die von dem Öffnungsrandbereich umgebene Bodenwandöffnung derart, dass das Abgasrohr in der von dem Öffnungsrandbereich umgebenen Bodenwandöffnung durch Presspassung gehalten ist.

According to a further aspect, the object specified at the outset is achieved by a method for producing a muffler for an exhaust system of an internal combustion engine, in particular a muffler constructed according to the invention, comprising the measures:

1. a) Providing at least one bottom wall for a muffler housing in such a way that at least one bottom wall opening formed in the bottom wall is surrounded by an opening edge region which is bent from a substantially planar bottom wall region essentially in the direction of a central axis of the opening in such a way that the bottom wall opening has a predetermined inside dimension, preferably inside diameter ,
2. b) providing an exhaust pipe to be accommodated in the bottom wall opening surrounded by the opening edge region and having a predetermined external dimension, preferably an external diameter, the predetermined external dimension of the exhaust pipe being larger than the predetermined internal dimension of the bottom wall opening,
3. c) inserting the exhaust pipe into the bottom wall opening surrounded by the opening edge portion such that the exhaust pipe is held in the bottom wall opening surrounded by the opening edge portion by press fitting.

It should be pointed out that the dimensions to be provided in a specific coordination with one another must be taken into account in those areas which interact with one another when the silencer is installed. This means that the exhaust pipe in the area in which it passes through a bottom wall when the silencer is installed is oversized compared to the bottom wall opening formed in the bottom wall to accommodate this exhaust pipe, but in other length areas it has, for example, a smaller cross-sectional dimension or possibly an even larger cross-sectional dimension can than this bottom wall opening.

It should also be pointed out that in a muffler constructed according to the invention or the method to be carried out according to the invention, such a bottom wall opening and an exhaust gas pipe to be accommodated therein are preferably each designed with a circular cross-section, so that the inner dimension can be represented by the inner diameter, for example, and the outer dimension, for example can be represented by the outer diameter.

In measure a), the opening edge region can be provided in the circumferential direction around the central axis of the opening. Alternatively, it can be provided that in measure a) the opening edge area is provided in an interrupted manner in at least one peripheral area. For example, the opening edge area can be formed with a plurality of opening edge area segments arranged at a distance from one another in the circumferential direction around the central axis of the opening.

In measure a), the opening edge area, starting from the essentially flat area of the bottom wall, can be provided with a decreasing distance to the opening center axis up to an axial area of the opening edge area with a minimum distance to the opening center axis.

Next, in measure a), the opening edge area with the area of the opening edge area with a minimum distance to the opening center axis up to be provided in a free axial end area of the opening edge area at a substantially constant distance from the central axis of the opening. Alternatively, in measure a), the opening edge area can be provided with an increasing distance from the opening center axis from the area of the opening edge area with a minimal distance to the central axis of the opening up to the free axial end area of the opening edge area.

In order to allow an exhaust pipe to be inserted into a base wall opening on the one hand and to achieve a sufficiently tight press fit on the other, it is proposed that a difference between the predetermined external dimension of the exhaust pipe and the predetermined internal dimension of the base wall opening provided for accommodating the exhaust pipe be in the range of 0.2 mm to 0.6 mm, preferably about 0.4 mm. For this purpose it can further be provided that in measure a) the at least one base wall is provided as a formed sheet metal part and/or with a wall thickness of at most 1 mm, preferably at most 0.6 mm

Furthermore, in order to achieve a stable connection, a measure d) can be provided for connecting the exhaust gas pipe to the opening edge area by material bonding, preferably welding.

Fig. 1

eine Teil-Axialansicht einer Bodenwand für einen Schalldämpfer im Bereich einer Bodenwandöffnung;

Fig. 2

eine Teil-Axialschnittansicht der Bodenwand der Fig. 1;

Fig. 3

eine Teilansicht der Bodenwand der Fig. 1 und 2 im Bereich der von einem Abgasrohr durchsetzten Bodenwandöffnung;

Fig. 4

eine der Fig. 3 entsprechende Prinzipdarstellung einer alternativen Ausgestaltungsart;

Fig. 5

eine weitere der Fig. 3 entsprechende Prinzipdarstellung zum Erläutern von Größenverhältnissen;

Fig. 6

eine weitere der Fig. 3 entsprechende Darstellung einer alternativen Ausgestaltung;

Fig. 7

eine prinzipartige Längsschnittdarstellung eines eine Mehrzahl von Bodenwände umfassenden Schalldämpfers.

The present invention is described in detail below with reference to the attached figures. It shows:

1

a partial axial view of a bottom wall for a muffler in the area of a bottom wall opening;

2

FIG. 12 is a partial axial section view of the bottom wall of FIG 1 ;

3

a partial view of the bottom wall of the Figures 1 and 2 in the area of the bottom wall opening through which an exhaust gas pipe passes;

4

one of the 3 Corresponding schematic representation of an alternative embodiment;

figure 5

another of the 3 Corresponding principle representation for explaining proportions;

6

another of the 3 Corresponding representation of an alternative embodiment;

Figure 7

a schematic longitudinal sectional view of a muffler comprising a plurality of bottom walls.

Before with regard to the Figures 1 to 6 Various types of design or design details of a bottom wall of a muffler for an exhaust system of an internal combustion engine, for example in a vehicle, are explained below with reference to FIG 7 an example of a basic structure of a silencer 10 is explained, which comprises a total of four bottom walls 12, 14, 16, 18 in the example shown. A muffler housing 20 of the muffler 10 also includes a longitudinal housing axis L, for example a substantially cylindrical peripheral wall 22 which is elongated and which is connected to the radially outer area of the bottom walls 12, 14, 16, 18 or surrounds them.

The bottom walls 12, 18 arranged on the axial end regions 24, 26 of the peripheral wall 22 form respective end walls of the muffler housing 20, which close off the inside of the muffler at the two axial ends. The bottom walls 12, 18 can be firmly and gas-tightly connected in their radially outer area to the peripheral wall 22 by material connection, for example welding. Alternatively or additionally, the bottom walls 12, 18 providing the respective end walls can be firmly and gas-tightly connected to the peripheral wall 22 in the axial end regions 24, 26 by positive locking, for example by flanging.

The bottom walls 12, 18 provided between the two end walls form respective intermediate walls which, together or in connection with the bottom walls 12, 18 providing the end walls, divide the silencer interior into a total of three chambers 28, 30, 32. The bottom walls 14, 16 providing intermediate walls can be held in a defined position, for example, on the inner circumference of the peripheral wall 22 by a clamping effect and/or material connection, for example welding.

In the example shown, the bottom walls 12, 14, 16, 18 each have, in a central area, a bottom wall opening 34, 36, 38, 40, the structure of which will be explained in more detail below. The bottom wall openings 34, 36 of the bottom walls 12, 14 are penetrated by an exhaust pipe 42, which can form an inlet pipe, for example, through which exhaust gas is introduced into the silencer interior. The bottom wall openings 38, 40 of the bottom walls 16, 18 are penetrated by an exhaust pipe 44, which can provide an outlet pipe, for example, through which exhaust gas is discharged from the muffler 10.

The exhaust pipe 42 can, for example, be open to the chamber 28 formed between the two bottom walls 12, 14 and can be open in an axial end region thereof to the chamber formed between the two bottom walls 14, 16. The chamber 28 can be in communication with the chamber 30 via one or more flow openings formed in the bottom wall 14 . The chamber 32 may form a resonator chamber of a Helmholtz resonator and be in communication with the chamber 30 via an exhaust pipe 46 provided in the bottom wall 16 and providing a resonator neck.

It should be noted that the foregoing with reference to the 7 described structure of a silencer is only an example and this structure can be varied in various aspects. This can relate to the number and the positioning of the bottom walls provided on the muffler, as well as the number of exhaust gas pipes leading into the muffler or the Exhaust gas from the exhaust pipes discharging from the muffler. The exhaust routing inside the silencer can also be implemented differently than in the example shown.

In the following, with reference to the Figures 1 to 6 the configuration of a bottom wall provided on the muffler 10 in that area in which an exhaust pipe passes through a bottom wall opening is described in detail. It should be pointed out that such an embodiment, as described below, can be implemented in each of the bottom walls provided in a muffler 10, i.e. in the example shown in each of the bottom walls 12, 14, 16, 18 where a respective exhaust pipe 42 and 44 interspersed with them. A configuration such as that described below could also be provided in association with the exhaust pipe 46 providing a resonator neck. Of course, it is also possible for differently shaped bottom wall openings to be provided in a bottom wall in order to guide an exhaust gas pipe through them, or for not all bottom wall openings provided in one or in different bottom walls to have the structure described below.

The structure of such a bottom wall is described below, for example with reference to the bottom wall 14, which forms an intermediate wall and separates the silencer interior from two chambers 28, 30 which are in exhaust gas exchange connection with one another.

the Figures 1 to 3 show that area of the bottom wall 14 in which the bottom wall opening 36 provided therein is penetrated by the exhaust pipe 42. In this area, on the bottom wall 14, an opening edge region 50, designed as a passage, for example, is bent from a bottom wall region 48 of the bottom wall 14 that is essentially flat and oriented essentially orthogonally to the longitudinal axis L of the housing, in the direction of the longitudinal housing axis L, which corresponds to a central opening axis M in the exemplary embodiment shown. For this purpose, the bottom wall 14 made up of sheet metal material is formed in the area of the bottom wall opening 36 using appropriate tools. It's on it It should be pointed out that an edge region bent in the direction of the longitudinal axis L of the housing can also be formed in the radially outer region, ie where the bottom wall 14 is held on the peripheral wall 22 .

In the exemplary embodiment of the bottom wall 14, which separates two chambers 28, 30 that are in exhaust gas exchange communication with one another, the opening edge area 50 can be interrupted in the circumferential direction and, for example, be constructed with four opening edge area segments 52 that follow one another in the circumferential direction and are arranged at a circumferential distance from one another, between which in the bottom wall 14 or the essentially flat bottom wall area 48, respective peripheral recesses 54 are formed, via which the two chambers 28, 30 separated from one another by the bottom wall 14 can be in exhaust gas exchange connection with one another.

If a gas-tight seal is to be provided by such a bottom wall, as is the case, for example, in connection with the bottom walls 12, 18 providing the end walls or also the bottom wall 16 providing an intermediate wall, the opening edge region 50 can be defined as the respective bottom wall opening 34, 40 or 38 can be formed completely surrounding and uninterrupted in the circumferential direction of the opening edge region.

In the design example Figures 1 to 3 the opening edge area 50 has a first edge section 58 adjoining the substantially planar bottom wall area 48 in a first bend area 56 . The first edge section 58 has a structure that tapers essentially in the manner of a cone or truncated cone with respect to the central opening axis M, starting from the first bend region 56, so that, starting from the first bend region 56, the distance between the first edge section 58 and the central opening axis M decreases in a substantially constant manner. This means that the first edge section 58, viewed in the axial direction, is essentially not curved, but of course has a structure that is curved like a circle around the central opening axis M, for example. A second bend region 60 follows the first Edge portion 58 a second edge portion 62 at. The second edge section 62 likewise has a cone-like or truncated-cone-like structure, so that its radial distance from the central opening axis M, starting from the second bending region 60, increases essentially constantly. The edge area of the opening 50 thus has a substantially V-shaped structure in longitudinal section between a first axial end area 64 adjoining the essentially planar bottom wall area 48 in the area of the first bend area 56 and a second axial end area 66 of the same, which is remote from the bottom wall area 48.

At the point where the two edge sections 58 , 62 adjoin one another, ie essentially in the area of the second bend area 60 , the opening edge area 50 is at a minimum distance from the opening center axis M of the bottom wall opening 36 . in the in figure 5 In the illustrated state, in which the exhaust gas pipe 42 has not yet passed through the bottom wall 14 or the bottom wall opening 36 formed therein, this minimum distance corresponds to a predetermined internal dimension a, which, particularly in the case of a substantially circular configuration of the bottom wall opening 36, is the radius of the bottom wall opening 36 with respect to the central axis M of the opening or the inside diameter, i.e. twice the radius.

The exhaust pipe 42 is dimensioned in such a way that its predetermined outer dimension A, for example also represented by the radius or twice the radius, i.e. the diameter, of the exhaust pipe 42, which is designed for example with a circular cross section, is larger than the corresponding predetermined inner dimension a of the bottom wall opening 36. For example, the outer dimension A, that is, for example, the diameter of the exhaust pipe 42 that corresponds to twice the radius R, can be oversized in the range of 0.2 mm to 0.6 mm, preferably about 0.4 mm, with respect to the corresponding inner dimension a, that is, for example the inside diameter of the bottom wall opening 36.

When assembling the muffler 10, after the bottom wall 14 has been provided with the shape provided for this purpose and has been surrounded by the peripheral wall 22 if necessary, the exhaust pipe 42 is inserted into the bottom wall opening 36 in the direction of the central opening axis M or the longitudinal housing axis L of the muffler 10. Due to the oversize of the exhaust pipe 42 in relation to the bottom wall opening 36 accommodating it, the opening edge region 50 is radially spread apart somewhat when the exhaust pipe 423 is inserted, so that the exhaust pipe 42 is held in the bottom wall opening 36 by a press fit and thus by a force fit. The opening edge area 50, which is radially expanded in the area of its elastic deformability, or its opening edge area segments 52, press with a force F radially inwards against the outer circumference of the exhaust pipe 42, so that on the one hand the exhaust pipe 42 is held in a defined position with respect to the bottom wall 14, and on the other hand by the of the force F against the outer circumference of the exhaust pipe 42 pressing opening edge area segments 52 a defined contact is produced on the exhaust pipe 42, so that the occurrence of rattling noises can be avoided.

The design of opening edge area 50 with its two edge sections 58, 62 essentially providing a V-shaped contour of opening edge area 50 creates an insertion bevel for exhaust pipe 42 to be accommodated in bottom wall opening 36, which allows easy insertion of exhaust pipe 42 into bottom wall opening 36 and avoids getting caught by a sharp-edged contact.

Even if the opening edge region 50 is designed with a shape that is not interrupted in the circumferential direction, ie as a continuous opening edge region in the circumferential direction, it can be spread open radially when the exhaust gas pipe 42 is inserted into the bottom wall opening 36 . If the structure of the opening edge region 50 is closed in the circumferential direction, it is advantageous if the bottom wall 14 is provided with a comparatively small wall thickness W of at most 1 mm, preferably at most 0.6 mm. With such a thin-walled configuration of the bottom wall 14 it is ensured that when the exhaust gas pipe 42 is inserted into the bottom wall opening 36 in the circumferential direction closed edge region 50 of the opening is correspondingly spread open due to the slight oversize of the exhaust pipe 42 and, due to its elasticity, then exerts the force F acting radially inwards substantially uniformly over the entire circumference on the exhaust pipe 42 .

An alternative embodiment of the bottom wall 14 is in 4 illustrated. The opening edge area 50 is also formed with two edge sections 58, 62 in this type of embodiment. The edge section 58 adjoins the substantially planar bottom wall section 48 in the axial end section 64 of the opening edge section 50 , while the edge section 62 provides the second axial end section 66 remote from the bottom wall section 48 . Both edge sections 58, 62 are curved in the axial direction and have a significantly larger radius of curvature than, for example, the two bend regions 56, 60 of 3 illustrated embodiment. For example, a substantially constant radius of curvature could be provided in each of the edge sections 58, 62 up to the area 68 with the minimum diameter of the opening edge area 50, and the radii of curvature in the two edge sections 58, 62 could, for example, be the same as one another, but could of course also be designed differently be. For example, the radius of curvature in edge section 62 could be smaller than the radius of curvature in edge section 58.

Also at the in 4 In the embodiment shown, the opening edge area 50 could be closed in the circumferential direction, as is required, for example, in the area of the bottom walls 12, 40 providing the respective end walls in order to obtain a gas-tight seal, but could alternatively also be provided with the configuration that is segmented in the circumferential direction as described above, on the one hand to provide increased flexibility in the area of the bottom wall opening, on the other hand to allow gas to pass through the bottom wall opening in this area.

Another alternative embodiment is 6 shown. In this configuration, the opening edge area 50 has neither the two edge portions 58, 62, which in respective bending areas 56, 60 connect to the substantially planar bottom wall area 48 and to one another. The edge section 58 has, for example, also in 3 recognizable cone-like or truncated cone-like structure with a substantially constant decrease in the distance from the opening center axis M between the two bending regions 56, 60. The second edge section 62 has an essentially cylindrical structure, i.e. it has an essentially constant distance from the central opening axis M between the second bent area 60 and the second axial end area 66, so that the minimum distance between the second bent area 60 and the second axial end area 66 is provided to the opening center axis M. In this configuration, an essentially flat contact area, that is to say one which extends further axially, is therefore provided between the opening edge area 50 and the exhaust gas pipe 42 . This is suitable for providing, in addition to the press fit generated by the force F exerted radially inward, a firm connection between the bottom wall 14 and the exhaust pipe 42 by material connection, for example by a weld seam 70 running in the circumferential direction, which is between a substantially axially oriented End face of the second edge portion 62 and the outer peripheral surface of the exhaust pipe 42 may be formed as a fillet weld.

Also at the in 6 In the embodiment shown, the opening edge area 50 can run all the way around in the circumferential direction, i.e. without interruption, or can be provided as an opening edge area that is interrupted in the circumferential direction at least at one point, for example as an opening edge area with a plurality of opening edge area segments that follow one another in the circumferential direction.

Finally, it should be pointed out once again that the above with reference to the Figures 1 to 6 described structure of a bottom wall opening or an opening edge area surrounding it can be provided for each bottom wall through which an exhaust gas pipe passes, wherein of course bottom wall openings or opening edge areas with different structures provided in different bottom walls can also be provided. This can for example be selected depending on the diameter of an exhaust pipe passing through a respective bottom wall, or on whether a gas-tight seal is to be achieved in the area of a bottom wall opening through which an exhaust pipe passes or whether exhaust gas should be able to pass through.

With each of the configurations of a bottom wall described above, there is the possibility of simply pushing an exhaust pipe through a respective bottom wall by hand or by machine or inserting it into a bottom wall opening provided for receiving an exhaust pipe, with the respective opening edge region being spread open and the frictional connection required to produce the press fit arises. During operation of a muffler constructed in this way, the various components of the same heat up and expand, so that the press fit or the force exerted on an associated exhaust pipe through a respective opening edge area increases and thus an even more intensified holding effect is generated.

Claims (16)

Muffler for an exhaust system of an internal combustion engine, comprising a muffler housing (20) with a peripheral wall (22) elongated in the direction of a housing longitudinal axis (L) and at least one chamber surrounded by the peripheral wall (22) and/or held on the peripheral wall (22). (28, 30, 32) in the bottom wall (12, 14, 16, 18) delimiting the muffler housing (20), wherein in at least one bottom wall (12, 14, 16, 18) at least one of a bottom wall region ( 48) of the bottom wall (12, 14, 16, 18) surrounded by an opening edge region (50) bent essentially in the direction of the housing longitudinal axis (L) and accommodating an exhaust gas pipe (42, 44) with a press fit is. Silencer according to Claim 1, characterized in that the opening edge region (50) is designed to run completely around a central opening axis (M) of the bottom wall opening (34, 36, 38, 40) in the circumferential direction. Silencer according to Claim 1, characterized in that the opening edge area (50) is formed to be interrupted in the circumferential direction around an opening center axis (M) of the bottom wall opening (34, 36, 38, 40), preferably wherein the opening edge area (50) has a plurality of in the circumferential direction around an opening central axis (M) of the bottom wall opening (34, 36, 38, 40) comprising spaced opening edge region segments (52). Silencer according to one of the preceding claims, characterized in that the at least one bottom wall (12, 14, 16, 18) is designed as a formed sheet metal part and/or that the at least one bottom wall (12, 14, 16, 18) has a wall thickness (W ) of at most 1 mm, preferably at most 0.6 mm. Silencer according to one of the preceding claims, characterized in that the opening edge area (50) has a first edge section (58) adjoining the substantially flat bottom wall area (48) in a first bend area (56) and a first edge section (58) in a second bend area (60) on the first edge portion (58) adjoining second edge portion (62), wherein a radial distance of the first edge portion (58) to an opening center axis (M) of the bottom wall opening (34, 36, 38, 40) in the direction from the first bend region (56) to the second bend region (60) preferably decreases substantially constantly. Silencer according to claim 5, characterized in that a radial distance of the second edge portion (62) to the opening central axis (M) in a direction away from the second bending region (60) is substantially constant. Silencer according to Claim 5, characterized in that a radial distance of the second edge section (62) from the central opening axis (M) increases preferably substantially constantly in the direction away from the second bending region (60). Silencer according to one of the preceding claims, characterized in that the opening edge area (50) extends from a first axial end area (64) of the opening edge area (50) adjoining the essentially flat bottom wall area (48) to an axial area (68) of the opening edge area (50 ) with a minimum distance to an opening center axis (M) of the bottom wall opening (34, 36, 38, 40). Silencer according to claim 8, characterized in that the opening edge area (50) from the area (68) of the opening edge area (50) at a minimum distance from the opening center axis (M) of Bottom wall opening (34, 36, 38, 40) to a substantially planar bottom wall portion (48) remote second axial end portion (66) of the opening edge portion (50) runs curved. Muffler according to one of the preceding claims, characterized in that the at least one bottom wall (14, 16) is an intermediate wall separating two chambers (28, 30, 32) in the muffler housing (20), or that the at least one bottom wall (12, 18) an end wall located at an axial end portion (24, 26) of the peripheral wall (22). Method for producing a muffler (10) for an exhaust system of an internal combustion engine, in particular a muffler (10) according to one of the preceding claims, comprising the measures: a) providing at least one bottom wall (12, 14, 16, 18) for a muffler housing (20) such that at least one bottom wall opening (34, 36, 38, 40) formed in the bottom wall (12, 14, 16, 18) of an opening edge region (50) which is bent essentially in the direction of a central opening axis (M) is surrounded by a substantially flat bottom wall region (48) in such a way that the bottom wall opening (34, 36, 38, 40) has a predetermined inside dimension (a), preferably inside diameter, having, b) providing an exhaust pipe (42, 44) to be received in the bottom wall opening (50) surrounded by the opening edge region (50) and having a predetermined outer dimension (A), preferably an outer diameter, the predetermined outer dimension (A) of the exhaust pipe (42, 44) being larger is the predetermined inside dimension (a) of the bottom wall opening (34, 36, 38, 40), c) inserting the exhaust pipe (42, 44) into the bottom wall opening (34, 36, 38, 40) surrounded by the opening edge area (50) in such a way that the exhaust pipe (42, 44) in the bottom wall opening (42, 44) surrounded by the opening edge area (50) 34, 36, 38, 40) is held by press fitting. Method according to Claim 11, characterized in that in measure a) the opening edge area (50) is provided in the circumferential direction around the central opening axis (M) completely all the way round, or that in measure a) the opening edge area (50) is provided in an interrupted manner in at least one peripheral area preferably with a plurality of opening edge region segments (52) spaced apart from one another in the circumferential direction about the central opening axis (M). Method according to Claim 11 or 12, characterized in that in measure a) the opening edge area (50), starting from the essentially flat bottom wall area (48), with up to an axial area (68) of the opening edge area (50) with a minimum distance to the opening center axis (M) decreasing distance to the opening center axis (M) is provided. Method according to Claim 13, characterized in that in measure a) the opening edge area (50) with from the area (68) of the opening edge area (50) with a minimum distance to the opening central axis (M) to a free axial end area of the opening edge area (50) a substantially constant distance from the central opening axis (M) is provided, or that in measure a) the opening edge area (50) with from the area (68) of the opening edge area (50) with a minimum distance to the central opening axis (M) to the free axial end area (50) of the opening edge area increasing distance to the opening central axis (M) is provided. Method according to one of Claims 11-14, characterized in that a difference between the predetermined outer dimension (A) of the exhaust pipe (42, 44) and the predetermined inner dimension (a) of the bottom wall opening (34 , 36, 38, 40) in the range from 0.2 mm to 0.6 mm, preferably about 0.4 mm, and/or that in measure a) the at least one bottom wall 12, 14, 16, 18) as a formed sheet metal part and/or with a wall thickness (W) of at most 1 mm, preferably at most 0.6 mm. Method according to one of Claims 11-15, characterized in that a measure d) is provided for connecting the exhaust gas pipe (42, 44) to the opening edge area (50) by material bonding, preferably welding.

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