EP4108890B1 - Method of manufacturing a silencer and corrresponding silencer - Google Patents

Description

The present invention relates to a method for producing a silencer.

From the EP 1 888 891 B2 a silencer manufactured using a method according to the preamble of claim 1 is known. In this known silencer, a silencer insert is constructed with two intermediate walls arranged at a distance from one another in the direction of a housing longitudinal axis of a silencer housing and accommodating a retaining wall between them. The silencer insert is surrounded by a peripheral wall that is elongated in the direction of the housing longitudinal axis. A peripheral wall opening formed in the peripheral wall is positioned such that it is opposite a retaining wall opening formed in the retaining wall. An exhaust gas guide pipe, which provides an inlet pipe in this known silencer, is introduced from the outside through the peripheral wall opening into the silencer housing such that it is positioned with a first pipe end region in the region of the peripheral wall and is fixed to the peripheral wall in this region by welding. A second pipe end region of the exhaust gas guide pipe is positioned engaging in or passing through the retaining wall opening and is connected to the retaining wall by a positive connection generated by mechanical deformation.

In one of the EN 10 2010 015 322 A1 In the known silencer, after a silencer insert has been surrounded by a peripheral wall, an exhaust gas guide pipe is guided from the outside through an opening in the peripheral wall and an opening in a retaining wall of the silencer insert and is secured to the retaining wall by locking.

The US 2015/0330283 A1 discloses a silencer in which, after a silencer insert has been surrounded by a peripheral wall, a

Essentially cylindrical sleeve is inserted through an opening in the peripheral wall into an exhaust gas guide pipe fixed to a retaining wall of the silencer insert and is secured by radial expansion.

The US 10, 267,207 B2 discloses a silencer in which an exhaust gas guide pipe to be secured to a peripheral wall and a retaining wall of a silencer insert has an external thread in its end region to be secured to the silencer insert, which external thread is screwed into an opening formed in the retaining wall in order to secure the exhaust gas guide pipe to the retaining wall.

It is the object of the present invention to provide a method for producing a silencer with which a simple to implement, yet stable structure is achieved.

1. a) Bereitstellen wenigstens eines Schalldämpfereinsatzes mit wenigstens einer Haltewand und wenigstens einer Haltewandöffnung in der wenigstens einen Haltewand,
2. b) Bereitstellen wenigstens eines ersten Abgasführungsrohrs,
3. c) Umgeben des wenigstens einen Schalldämpfereinsatzes mit einer Umfangswand eines Schalldämpfergehäuses, wobei in der Umfangswand in Zuordnung zu der wenigstens einen Haltewandöffnung eine Umfangswandöffnung vorgesehen ist,
4. d) Anordnen des wenigstens einen ersten Abgasführungsrohrs derart, dass ein erster Rohrendbereich des wenigstens einen ersten Abgasführungsrohrs in die in Zuordnung zu der wenigstens einen Haltewandöffnung vorgesehene Umfangswandöffnung eingreifend positioniert wird und ein zweiter Rohrendbereich des wenigstens einen ersten Abgasführungsrohrs in der wenigstens einen Haltewandöffnung durch Kraftschluss oder Verrastung gehalten wird,
5. e) Verbinden des wenigstens einen ersten Abgasführungsrohrs durch Materialschluss mit der Umfangswand im Bereich der Umfangswandöffnung.

According to the invention, the object is achieved by a method for producing an exhaust silencer, comprising the measures:

1. a) providing at least one silencer insert with at least one retaining wall and at least one retaining wall opening in the at least one retaining wall,
2. b) providing at least one first exhaust gas guide pipe,
3. c) surrounding the at least one silencer insert with a peripheral wall of a silencer housing, wherein a peripheral wall opening is provided in the peripheral wall in association with the at least one retaining wall opening,
4. d) arranging the at least one first exhaust gas guide pipe in such a way that a first pipe end region of the at least one first exhaust gas guide pipe is positioned so as to engage in the peripheral wall opening provided in association with the at least one retaining wall opening and a second pipe end region of the at least one first exhaust gas guide pipe is held in the at least one retaining wall opening by frictional engagement or locking,
5. e) connecting the at least one first exhaust gas guide pipe by material bonding to the peripheral wall in the region of the peripheral wall opening.

The positioning of the at least one first exhaust gas guide pipe with its first pipe end region in an associated peripheral wall opening can be carried out particularly easily, since in measure a) the at least one first exhaust gas guide pipe is positioned engaging in the at least one retaining wall opening and in measure d) its first pipe end region is moved from the inside in the direction of the peripheral wall opening until the first pipe end region is positioned engaging in the peripheral wall opening and the second pipe end region is held on the at least one retaining wall engaging in the at least one retaining wall opening by frictional engagement or locking. The peripheral wall formed to provide the peripheral wall opening can develop a funnel effect which guides the first pipe end region into the peripheral wall opening.

• ein Schalldämpfergehäuse mit der in Richtung einer Gehäuselängsachse langgestreckten Umfangswand und einer Stirnwand an jedem axialen Endbereich der Umfangswand,
• den von der Umfangswand umgebenen und an der Umfangswand getragenen Schalldämpfereinsatz mit der wenigstens einer im Wesentlichen in Richtung der Gehäuselängsachse sich erstreckenden Haltewand,
• das wenigstens eine erste Abgasführungsrohr, wobei das wenigstens eine erste Abgasführungsrohr mit seinem ersten Rohrendbereich in die Umfangswandöffnung in der Umfangswand eingreifend positioniert ist und an der Umfangswand festgelegt ist und mit seinem zweiten Rohrendbereich an der wenigstens einen Haltewand gehalten ist.

A silencer for an exhaust system of an internal combustion engine produced by the method according to the invention comprises:

• a silencer housing with the peripheral wall elongated in the direction of a housing longitudinal axis and an end wall at each axial end region of the peripheral wall,
• the silencer insert surrounded by the peripheral wall and supported on the peripheral wall with at least one retaining wall extending substantially in the direction of the housing longitudinal axis,
• the at least one first exhaust gas guide pipe, wherein the at least one first exhaust gas guide pipe is positioned with its first pipe end region engaging in the peripheral wall opening in the peripheral wall and is fixed to the peripheral wall and is held with its second pipe end region on the at least one holding wall.

The at least one first exhaust gas guide pipe is held in its second pipe end region on the retaining wall by frictional connection or locking.

In the silencer produced using the method according to the invention, the first exhaust pipe is not held on the retaining wall by forming and thus the positive connection generated by the forming between the exhaust pipe and a retaining wall, but by measures that do not require any forming of the first exhaust pipe and the retaining wall during or after the exhaust pipe is moved into its installation position. Both the shapes of both the first exhaust pipe and the retaining wall required to achieve the frictional connection, i.e. a holding effect through the frictional force acting between the first exhaust pipe and the retaining wall, and the shapes of both the first exhaust pipe and the retaining wall required to achieve the locking are provided before assembly. During assembly, the components to be held together, i.e. the at least one first exhaust pipe and the retaining wall, are only moved relative to one another. During this movement, a slight deformation of the retaining wall, for example, which is completely within the range of elasticity, can occur in order to achieve the frictional connection. A deformation of the retaining wall, for example, which is within the range of elasticity, can also occur temporarily when the locking is being produced. However, such deformations occurring in the area of elasticity of the components involved do not constitute a transformation of the components concerned that leads to a new shape and a resulting positive connection, in particular not a transformation that is only generated by the action of tools on these components after the two components have been brought into the relative positioning required for assembly.

In order to achieve a gas-tight closure of the silencer to the outside, the at least one first exhaust gas guide pipe can be connected to the peripheral wall by welding.

The at least one first exhaust gas guide pipe can be an inlet pipe through which exhaust gas is introduced into the interior of the muffler.

For a stable holding interaction between the holding wall and the at least one first exhaust gas guide pipe, it is proposed that in the at least one Retaining wall in association with the at least one first exhaust gas guide pipe, a retaining wall opening is provided which is at least partially surrounded by a bent fastening edge region of the at least one retaining wall, and that the at least one first exhaust gas guide pipe is positioned with its second pipe end region engaging in the retaining wall opening and is held in the retaining wall opening in the region of the fastening edge region by a press fit. When the first exhaust gas guide pipe is inserted into the retaining wall opening surrounded by the fastening edge region, the fastening edge region can be spread radially somewhat in the region of its elastic deformability, whereby the frictional force generating the frictional connection can be efficiently provided by pre-tensioning the fastening edge region against the outer surface of the exhaust gas guide pipe.

Depending on the direction in which the at least one first exhaust gas guide pipe is moved during assembly with respect to the at least one retaining wall, the fastening edge region can be bent in the direction of the first pipe end region of the at least one first exhaust gas guide pipe, or the fastening edge region can be bent in the direction away from the first pipe end region of the at least one first exhaust gas guide pipe. The fastening edge region is preferably bent in the direction in which the at least one first exhaust gas guide pipe is moved with respect to the retaining wall. This prevents the fastening edge region from becoming jammed, or the at least one first exhaust gas guide pipe can be easily inserted into the retaining wall opening surrounded by the fastening edge region.

For a stable frictional connection between the at least one first exhaust gas guide pipe and the at least one retaining wall, a contact point that runs completely around the circumference between the at least one first exhaust gas guide pipe and the at least one retaining wall can be provided in the region of the retaining wall opening provided on the at least one retaining wall in association with the at least one first exhaust gas guide pipe.

The introduction of the at least one first exhaust gas guide pipe into the associated retaining wall opening can be carried out more easily if, in order to provide the frictional connection between the at least one first exhaust gas guide pipe and the at least one retaining wall in the region of the retaining wall opening provided on the at least one retaining wall in association with the at least one first exhaust gas guide pipe, a contact between the at least one first exhaust gas guide pipe and the at least one retaining wall is provided in at least one circumferential region, which contact is interrupted.

For this purpose, it can be provided, for example, that in the at least one retaining wall in the region of the retaining wall opening provided on the at least one retaining wall in association with the at least one first exhaust gas guide pipe, at least one, preferably a plurality of, preferably slot-like, wall interruption regions are provided, which are arranged at a distance from one another in the circumferential direction around the retaining wall opening and are open to the retaining wall opening. Thus, a plurality of tongues effective for the frictional connection and which follow one another in the circumferential direction and are separated from one another by wall interruption regions are provided on the retaining wall, which tongues can be elastically deformed relatively easily when a first exhaust gas guide pipe is inserted.

To provide the locking, a locking formation can be provided on the second pipe end region of the at least one first exhaust gas guide pipe, and a counter-locking formation in locking engagement with the locking formation can be provided on the at least one retaining wall in association with the locking formation.

In an embodiment which avoids a constriction of the exhaust gas flow volume in the at least one first exhaust gas guide pipe, it is proposed that the locking formation comprises at least one locking projection which projects radially outward with respect to a pipe longitudinal axis of the at least one first exhaust gas guide pipe.

Depending on the design of the counter-latching formation, the latching formation can comprise at least two latching projections that follow one another in the direction of the longitudinal axis of the pipe, and/or the latching formation can comprise at least two latching projection segments that follow one another in the circumferential direction around the longitudinal axis of the pipe.

If at least one, preferably each locking projection is provided by a bead-like formation of the at least one first exhaust gas guide pipe, the at least one first exhaust gas guide pipe can be provided with the locking formation in a simple manner. However, unlike in the prior art, the required shaping of the exhaust gas guide pipe takes place before it is integrated into the silencer in a processing phase in which this exhaust gas guide pipe is easy to handle as an individual component.

A retaining wall opening can be provided in the at least one retaining wall in association with the at least one first exhaust gas guide pipe, wherein a plurality of preferably slot-like wall interruption regions arranged around the retaining wall opening at a circumferential distance from one another and open to the retaining wall opening can also be provided in the at least one retaining wall, and a locking tongue of the counter-locking formation can be formed between at least two wall interruption regions that immediately follow one another in the circumferential direction.

To produce the locking state, at least one, preferably each locking tongue of the counter-locking formation can engage between two locking projections of the locking formation that follow one another in the direction of the longitudinal axis of the pipe.

In another embodiment, a locking recess for receiving at least one locking projection of the locking formation can be provided on at least one, preferably each locking tongue.

In order to avoid mutual contact between a retaining wall and a first exhaust pipe in sharp-edged areas, it is proposed that a bent locking tongue edge region is provided on the at least one retaining wall for at least one, preferably each, locking tongue.

If the locking formation comprises two locking projections arranged at an axial distance from one another, at least one, preferably each locking tongue edge region can engage between two locking projections of the locking formation which follow one another in the direction of the longitudinal axis of the pipe.

In an alternative embodiment, at least one locking recess can be provided on at least one, preferably each, locking tongue edge region.

The silencer insert may comprise at least two intermediate walls arranged substantially orthogonally to the housing longitudinal axis and supported on the peripheral wall, wherein the at least one retaining wall is fixed to one of the intermediate walls in each of two opposite end regions thereof.

Furthermore, the silencer insert can comprise at least one second exhaust gas guide pipe, preferably an outlet pipe, wherein an intermediate wall opening is provided in at least one of the intermediate walls connected to the at least one retaining wall in association with the at least one second exhaust gas guide pipe, and an end wall opening is provided in one of the end walls, wherein the at least one second exhaust gas guide pipe is positioned engaging in the intermediate wall opening and the end wall opening and is fixed in the region of the end wall opening to the end wall having this and/or in the region of at least one intermediate wall opening to the intermediate wall having this by material bonding.

In measure a), the at least one silencer insert can be provided such that the at least one retaining wall is connected to an intermediate wall in each of two opposite end regions thereof.

Furthermore, in measure c), the at least one silencer insert can be surrounded by the peripheral wall by winding a plate-like peripheral wall blank around the at least one silencer insert. In an alternative procedure, in measure c), the at least one silencer insert can be surrounded by providing the peripheral wall with a structure closed in the peripheral direction and inserting the at least one silencer insert into the peripheral wall provided with a structure closed in the peripheral direction.

To close the silencer housing at its axial end regions, a measure f) can be provided for fixing an end wall at each of the axial end regions of the peripheral wall elongated in the direction of a housing longitudinal axis by material closure and/or form closure before or after implementation of measure c).

The invention further relates to an exhaust system for an internal combustion engine, comprising at least one silencer constructed according to the invention, which has been produced using a method according to the invention

Fig. 1

eine perspektivische Ansicht eines Schalldämpfereinsatzes;

Fig. 2

einen Schalldämpfer mit dem Schalldämpfereinsatz der Fig. 1 bei teilweise weggebrochen dargestellter Umfangswand eines Schalldämpfergehäuses;

Fig. 3

ein an einer Haltewand gehaltenes Abgasführungsrohr des Schalldämpfers der Fig. 2 in perspektivischer Ansicht;

Fig. 4

das an der Haltewand gehaltene Abgasführungsrohr des Schalldämpfers der Fig. 2 in anderer perspektivischer Ansicht;

Fig. 5

eine Herstellungsphase des Schalldämpfers der Fig. 2 mit noch nicht in eine Umfangswandöffnung eingreifend positioniertem Abgasführungsrohr;

Fig. 6

eine der Fig. 5 entsprechende Darstellung mit in die Umfangswandöffnung eingreifend positioniertem Abgasführungsrohr;

Fig. 7

eine der Fig. 2 entsprechende Darstellung bei einer alternativen Ausgestaltungsart eines Schalldämpfers;

Fig. 8

eine Haltewand des Schalldämpfers der Fig. 7;

Fig. 9

in ihren Darstellungen a), b) und c) verschiedene Ausgestaltungsarten von durch Verrastung an einer Haltewand gehaltenen Abgasführungsrohren;

Fig. 10

eine Querschnittansicht der in Fig. 9a) dargestellten Ausgestaltungsart.

The invention is described in detail below with reference to the accompanying figures.

Fig.1

a perspective view of a silencer insert;

Fig.2

a silencer with the silencer insert of the Fig.1 with the peripheral wall of a silencer housing partially broken away;

Fig.3

an exhaust pipe of the silencer held on a retaining wall of the Fig.2 in perspective view;

Fig.4

the exhaust pipe of the silencer held on the retaining wall of the Fig.2 in a different perspective view;

Fig.5

a manufacturing phase of the silencer of the Fig.2 with the exhaust gas guide pipe not yet positioned so as to engage in a peripheral wall opening;

Fig.6

one of the Fig.5 corresponding illustration with the exhaust gas guide pipe positioned so as to engage in the peripheral wall opening;

Fig.7

one of the Fig.2 corresponding representation for an alternative design of a silencer;

Fig.8

a retaining wall of the silencer of the Fig.7 ;

Fig.9

in their representations a), b) and c) various designs of exhaust gas guide pipes held by locking to a retaining wall;

Fig.10

a cross-sectional view of the Fig. 9a ) shown in the design.

In Fig.1 A silencer integrated, for example, as a transverse silencer in an exhaust system 10 of an internal combustion engine in a vehicle is generally designated with 12. The silencer 12 comprises a silencer housing 14 which is elongated in the direction of a housing longitudinal axis L and has a peripheral wall 16 surrounding the housing longitudinal axis L. End walls 22, 24 are fixed to both axial end regions 18, 20 of the peripheral wall 16. The peripheral wall 16 and the end walls 22, 24 are provided, for example, as formed sheet metal parts.

A silencer insert, generally designated 26, is provided inside the silencer housing 14. In the embodiment shown, this comprises four Fig.2 also recognizable partition walls 28, 30, 32, 34, for example designed as formed sheet metal parts, which divide the interior of the silencer housing 14 into five chambers 36, 38, 40, 42, 44 that follow one another in the direction of the housing's longitudinal axis L. Openings can be provided in the partition walls 28, 30, 32, 34, via which the chambers 36, 38, 40, 42, 44 can communicate with one another.

The silencer insert 26 further comprises a retaining wall 46 which extends essentially in the direction of the housing longitudinal axis L and is oriented essentially orthogonally to the intermediate walls 28, 30, 32, 34 and is designed, for example, as a formed sheet metal part. In its two axial end regions 48, 50, the retaining wall 46 is firmly connected to the two intermediate walls 30, 32, for example by welding.

The silencer 12 of the Fig.1 Furthermore, a first exhaust gas guide pipe 44 is provided, which provides an inlet pipe and through which exhaust gas is guided into the chamber 40 in the silencer housing 14. In order to discharge the exhaust gas from the silencer housing 14, two second exhaust gas guide pipes 52, 54, each providing an outlet pipe, are provided. In association with each second exhaust gas guide pipe 52, 54, an intermediate wall opening is provided in each of the intermediate walls 28, 30, 32, 34. Each of the intermediate wall openings can be surrounded by a bent fastening edge region formed on the respective intermediate wall, into which the respective second exhaust gas guide pipe 52, 54 is inserted. Advantageously, in the region of each such fastening edge region or each intermediate wall opening, the respective second exhaust gas guide pipe 52, 54 can be firmly connected to the respective intermediate wall 28, 30, 32, 24 by material bonding, in particular for welding. A circumferential weld seam can be provided here, or individual welding points can be provided to achieve the solid connection.

In association with the second exhaust gas guide pipe 52, a front wall opening is provided in the end wall 22 arranged at the axial end region 18 of the peripheral wall 16, into which the second exhaust gas guide pipe 52 is positioned so as to engage. In the area of this front wall opening, a fastening edge region, for example bent outwards, can be provided on the end wall 22. The second exhaust gas guide pipe 52 can be connected to the end wall 22 in the area of this fastening edge region by a preferably circumferential weld seam. Likewise, on the end wall 24 provided at the axial end region 20 of the peripheral wall 16, a An end wall opening is formed which is surrounded by an outwardly bent fastening edge region and into which the second exhaust gas guide pipe 54 is positioned so as to engage. Here too, a completely circumferential welded connection can be formed for a gas-tight seal between the second exhaust gas guide pipe 54 and the end wall 24.

Inside the silencer housing 14, the second exhaust gas guide pipes 52, 54 can have openings through which they are open to various of the chambers 36, 38, 40, 42, 44. Additional pipes can also be provided inside the silencer housing 14, which provide a connection between various of the chambers 36, 38, 40, 42, 44. For example, a Helmholtz resonator can be provided by means of a pipe 56 that opens into the otherwise closed chamber 44. It should be noted that the internal structure of the silencer 12 is only shown as an example and can be designed differently in various aspects, for example with regard to the number of partition walls, chambers, pipes and also the course of pipes, than shown in the figures.

The following explains how the first exhaust pipe 44 is integrated into the silencer 12 and how the first exhaust pipe 44 is integrated into the silencer 12. A first design variant for this is described below with reference to the Fig. 3 to 6 explained in more detail.

The Fig. 3 and 4 show the retaining wall 46 and the first exhaust pipe 44 in a pre-assembly state, i.e. before the silencer insert 26 is surrounded by the peripheral wall 16. Fig. 3 to 6 that a retaining wall opening 58 is formed in the retaining wall 46, for example in a central region thereof. A fastening edge region 60, which preferably runs completely around the retaining wall opening 58, is provided on the retaining wall 46, surrounding the retaining wall opening 58. The fastening edge region 60 is bent away from the retaining wall 46, for example by forming a passage, and has a substantially cylindrical structure.

The first exhaust gas guide pipe 44 has two pipe end regions 62, 64. Before the silencer insert 26 is surrounded by the peripheral wall 16, the first exhaust gas guide pipe 44 is inserted into the retaining wall opening 58 in such a way that the first exhaust gas guide pipe 44 is positioned in the region of its second pipe end region 64 in the retaining wall opening 58. The first exhaust gas guide pipe 44 can, for example, be inserted into the retaining wall opening 58 in the region of its second pipe end region 64 before the retaining wall 46 is connected to the two intermediate walls 30, 32 in the Fig. 3 and 4 shown positioning into the retaining wall opening 58, so that this process can be carried out without interference from the second exhaust gas guide pipes 52, 54 also provided on the silencer insert 26.

When inserting the first exhaust gas guide pipe 44 into the retaining wall opening 58, the first exhaust gas guide pipe 44 can be moved with its first pipe end region 62 in an insertion direction in which the fastening edge region 60 extends from the retaining wall 46. Thus, the rounded transition formed during the manufacture of the fastening edge region 60 between the essentially planar region of the retaining wall 46 and the fastening edge region 60 can be used as an insertion bevel.

The inner dimensions of the retaining wall opening 58 or of the fastening edge region 60 and the outer dimensions of the, for example, essentially cylindrical first exhaust gas guide pipe 44 are coordinated with one another in such a way that the first exhaust gas guide pipe 44 is held by a press fit in the retaining wall opening 46 or by the fastening edge region 60. When the first exhaust gas guide pipe 44 is inserted into the retaining wall opening 58, the fastening edge region 60 is slightly spread radially within the scope of its elastic deformability, so that it presses against the outer circumferential surface of the first exhaust gas guide pipe 44 under prestress. A force connection is thus created between the first exhaust gas guide pipe 44 and the retaining wall 46, i.e. a holding effect generated by frictional interaction, which prevents an unwanted displacement of the first exhaust gas guide pipe 44 with respect to the retaining wall 46, but fundamentally allows the first Exhaust gas guide pipe 44 with respect to the retaining wall 46 in the direction of a pipe longitudinal axis R of the first exhaust gas guide pipe and in the circumferential direction about the pipe longitudinal axis R, thus allowing a rotational movement.

The silencer insert 26 supplemented in this way with the first exhaust gas guide pipe 44 is then surrounded by the peripheral wall 16. This can be done, for example, by first providing a plate-like sheet metal blank of the peripheral wall 16 with a peripheral wall opening 66 associated with the retaining wall opening 58. This peripheral wall opening 66 can also be provided by a passage, so that an outward-facing fastening edge region 68 is created in the region of the peripheral wall opening 66. The plate-like sheet metal blank provided with the peripheral wall opening 66 can then be bent into a tubular closed structure and connected in its two edge regions which are then positioned adjacent to one another, for example by welding and/or flanging or the like.

The silencer insert 26 is then inserted in the direction of the housing longitudinal axis L into the peripheral wall 16 provided in this way with a closed structure in the peripheral direction until its installation position is reached and the retaining wall opening 58 is positioned in the direction of the housing longitudinal axis L in the region of the peripheral wall opening 66. In this state, the first exhaust gas guide pipe 44 lies with its first pipe end region 62 on the inside of the peripheral wall 16 opposite the peripheral wall opening 66.

In a subsequent work step, a tool is used to engage the first exhaust gas guide pipe 44 and move or pull it in a direction of movement B with the first pipe end region 62 leading towards the peripheral wall opening 66 or the fastening edge region 68 surrounding it. The first exhaust gas guide pipe 44 moves with its second pipe end region 64 in the retaining wall opening 58 until the Fig.6 shown state is reached, in which the first pipe end region 62 is positioned engaging in the peripheral wall opening 66 and is thus surrounded by the fastening edge region 68 and the second pipe end region 64 is positioned engaging in the retaining wall opening 58 and is surrounded by the fastening edge region 60 and, as already stated, is held in the retaining wall opening 58 by frictional engagement.

The process of moving the first exhaust gas guide pipe 44 in the direction of movement B to insert the first pipe end region 62 into the peripheral wall opening 66 can therefore be carried out comparatively easily, since the peripheral wall 16 with its curved transition region to the fastening edge region 68 also provides an insertion bevel through which the first pipe end region 62 is guided into the peripheral wall opening 66, and since the fastening edge region 60 on the holding wall 46 is also bent in the direction of the peripheral wall opening 66 or the first pipe end region 62, i.e. in the direction in which the first exhaust gas guide pipe 44 is moved in order to insert the first pipe end region 62 into the peripheral wall opening 66. Neither in the area of the retaining wall opening 58 nor in the area of the peripheral wall opening 66 is there any danger that a sharp-edged area of the retaining wall 46 or the peripheral wall 16 will become jammed on the outer surface of the first exhaust gas guide pipe 44.

The peripheral wall opening 66 can be dimensioned in such a way that a frictional connection with the first pipe end region 62 of the first exhaust gas guide pipe 44 is also created there when the latter is introduced into the peripheral wall opening 66. Alternatively or additionally, the peripheral wall opening 66 can be designed with a slight oversize in relation to the external dimensions of the first exhaust gas guide pipe 44 in its first pipe end region 66, so that the first exhaust gas guide pipe 44 with its first pipe end region 62 is accommodated in the peripheral wall opening 66 or in the fastening edge region 68 with little play for movement.

After the first exhaust gas guide pipe 44 has been introduced into the peripheral wall opening 66 in such a way that the first exhaust gas guide pipe 44 ends with its first pipe end region 62, for example in the direction of the pipe longitudinal axis R, essentially flush with the fastening edge region 68 or slightly protrudes outwards beyond this, the first exhaust gas guide pipe 44 can be connected to the peripheral wall 16 in the region of the fastening edge region 68 by a weld seam that preferably runs all the way around in the circumferential direction in order to ensure a gas-tight seal. During this process, for example, another exhaust gas guide pipe can already have been inserted into the first exhaust gas guide pipe 44 and thus be connected to the first exhaust gas guide pipe 44 or the peripheral wall 16 by the same weld seam.

In a subsequent operation, the two end walls 22, 24 can then be arranged on the axial end regions 18, 20 of the peripheral wall 16 and connected to it in a fixed and gas-tight manner by welding and/or by form-fitting, for example by flanging. The second exhaust gas guide pipes 52, 54 passing through or engaging in the respective end wall openings can also be connected to the end walls 22, 24 in a fixed and gas-tight manner by means of circumferential weld seams.

In the silencer 12 manufactured in the manner described above, the first exhaust gas guide pipe 44 is held in its two pipe end regions 62, 44 stably on the peripheral wall 16 or the retaining wall 46 and thus on the silencer insert 26, in particular against evasive movements transverse to the pipe longitudinal axis R. Since the welding of the first exhaust gas guide pipe 44 to the peripheral wall 16 in the first pipe end region 62 reliably holds the latter against displacement in the direction of the pipe longitudinal axis R, it is not necessary to weld the first exhaust gas guide pipe 44 after it has been welded in the manner described in Fig.6 shown installation position, in its second pipe end region 64 interacting with the retaining wall 46 in such a way that in this region too a form fit is generated between the retaining wall 46 and the first exhaust pipe 44, preventing movement in the direction of the pipe's longitudinal axis R. Nevertheless, it should be noted that the force fit generated between the retaining wall 46 and the first exhaust pipe 44 also provides a defined axial support of the first Exhaust guide pipe 44 in the direction of the pipe longitudinal axis R in the silencer 12.

The Figs. 7 and 8 show a modification of the previously described design of the silencer 12. One can see in the Figs. 7 and 8 that a plurality of slot-like wall interruption regions 70 are provided in the retaining wall 46, which extend essentially radially with respect to the retaining wall opening 58 or an opening center axis M. In the circumferential direction around the opening center axis M, a retaining wall tongue 72 is formed between each two such wall interruption regions 70. Since in the embodiment example shown a total of four slot-like wall interruption regions 70 are provided and are open radially inward towards the retaining wall opening 58, four such retaining wall tongues 72 are provided surrounding the retaining wall opening 58.

The wall interruption regions 70 extend into the region of the fastening edge region 60 and thus also interrupt this in the circumferential direction, so that the fastening edge region 60 provides a retaining wall tongue edge region 74 in association with each retaining wall tongue 72.

In the Figs. 7 and 8 In the embodiment of the retaining wall 46 shown, the fastening edge region 60 on the retaining wall 46 is provided in such a way that, when the silencer insert 26 is surrounded by the peripheral wall 16, it extends in the direction of the peripheral wall opening 66 provided in the peripheral wall 16, as shown in the Fig. 5 and 6 is shown, extends away. When assembling the muffler 12, after the muffler insert 26 has been surrounded by the peripheral wall 16, in a procedure not corresponding to the principles of the present invention, the first exhaust gas guide pipe 44 with its second pipe end region 64 can be moved from the outside through the peripheral wall opening 66 in the direction of the retaining wall 46 until the second pipe end region 64 enters the retaining wall opening 58 or is inserted into it with a press fit. In this case, the retaining wall tongues 72 can give way in the area of their elastic deformability or in the direction of movement of the first exhaust gas guide pipe 44 be displaced, whereby the fastening edge region 60 with its retaining wall tongue edge regions 74 is slightly spread radially and, due to the elasticity of the retaining wall 46, presses from the outside radially against the outer circumferential surface of the first exhaust gas guide pipe 44 in the second pipe end region 64. This also generates a holding effect through frictional connection, i.e. through frictional interaction between the first exhaust gas guide pipe 44 and the retaining wall 46 and thus the silencer insert 26.

Subsequently, the first exhaust gas guide pipe 44 can be fixed in the region of its first pipe end region 62 in the manner described above to the peripheral wall 16 in the region of the peripheral wall opening 66 or the fastening edge region 68.

It should be noted that even in the Figs. 7 and 8 In the embodiment shown, the fastening edge region 60 on the retaining wall 46 could be provided in such a way that, when the silencer insert 26 is surrounded by the peripheral wall 16, it extends in the direction of the associated peripheral wall opening 66. In such an embodiment, the first exhaust gas guide pipe 44 can then be arranged in one of the Fig.5 in a manner corresponding to the principles of the present invention on the retaining wall 46 before the silencer insert 26 with the first exhaust gas guide pipe 44 already provided thereon is surrounded by the peripheral wall 16. The first exhaust gas guide pipe 44 can then be repositioned in the manner shown in Fig.5 shown direction of movement B from the inside with its first pipe end region 62 through the peripheral wall opening 66 or into it and then firmly connected to the peripheral wall 16 by welding. Similarly, in the case of the Fig. 3 to 6 In the embodiment shown, the fastening edge region 60 on the retaining wall 46 can be bent in such a way that it extends in the direction away from the associated peripheral wall opening 66. In this embodiment, the first exhaust gas guide pipe 44, after the silencer insert 26 has been surrounded by the peripheral wall 16, can then be connected from the outside to its second Pipe end region 64 is first introduced through the peripheral wall opening 66 and then into the retaining wall opening 58. It can thus be seen that the fastening edge region 60, which contributes significantly to generating the frictional connection between the retaining wall 46 and the first exhaust gas guide pipe 44, is advantageously provided bent on the retaining wall 46 in the direction in which the first exhaust gas guide pipe 44 is moved in order to position the first pipe end region 62 thereof in the peripheral wall opening 66.

It is further pointed out that the process of surrounding the silencer insert 46 with the peripheral wall 16 could also be carried out in a different way. This peripheral wall blank, which is provided as a plate-like blank and is provided with the peripheral wall opening 66 or the fastening edge region 68, could, for example after it has already been pre-bent into a curved or tube-like structure, be positioned or wound around the silencer insert 26, whereupon the peripheral wall blank is then connected in the adjacent edge regions by welding and/or by positive locking to provide the structure closed in the circumferential direction. The two end walls 22, 24 could also be provided on the silencer insert before the silencer insert 26 is surrounded by the peripheral wall 16 and then, when the silencer insert 26 is positioned inside the peripheral wall 16 or the silencer housing 14 either by being pushed into the circumferentially closed structure of the peripheral wall 16 or by being surrounded by a peripheral wall 16 that is initially still open in the circumferential direction, be connected to the peripheral wall 16 in its two axial end regions 18, 20.

With reference to the Figs. 9 and 10 An alternative embodiment is described below, which enables a connection of the first exhaust gas guide pipe 44 in its second raw end region 64 to the retaining wall 66 without the need for a deformation of the first exhaust gas guide pipe 44 or the retaining wall 46 after positioning the first exhaust gas guide pipe 64 in the retaining wall opening 58. The Fig. 9a), 9b) and 9c ) each follow the same functional principle underlying different variants of this embodiment, in which a holding interaction between the holding wall 46 and the first exhaust gas guide pipe 44 is generated by locking.

The Fig. 9a ) shows in conjunction with Fig.10 that on the retaining wall 46, in association with the retaining wall opening 58, there are again four slot-like wall interruption regions 70 that are open radially inward toward the retaining wall opening 58. These also extend into the fastening edge region 60, so that locking tongue edge regions 78 of the fastening edge region 60 are formed in association with the locking tongues 76 formed between two wall interruption regions 70 that are adjacent in the circumferential direction. In each of these locking tongue edge regions 78, a bulge is formed that is directed radially outward with respect to the opening center axis M of the retaining wall opening 58 and provides a locking recess 80 that is open radially inward.

At the second pipe end region 64 of the first exhaust gas guide pipe 44, a bead-like formation is formed which runs completely around the pipe longitudinal axis R in the circumferential direction and which forms a locking projection 82 which projects radially outward with respect to the pipe longitudinal axis R.

The first exhaust gas guide pipe 44 provides a locking formation 84 with the locking projection 82, while a counter-locking formation, generally designated 86, is provided on the retaining wall 46 with the segments of the locking recess 80 formed in the locking tongue edge regions 78.

When constructing the silencer 12, the silencer insert 26 can be surrounded by the peripheral wall 16 in the manner described above. The fastening edge region 60 is provided with its locking tongue edge regions 78 such that the locking tongue edge regions 78 extend in the direction away from the associated peripheral wall opening 66. Subsequently, in a manner not corresponding to the principles of the present invention, the first exhaust gas guide pipe 44 can be guided through the peripheral wall opening 66 with its second pipe end region 64 in the direction of the retaining wall 46 until the locking projection 82 comes into contact with the radially inner end regions of the locking tongues 76. When the first exhaust gas guide pipe 44 moves further into the silencer housing 14, the locking projection 82 takes the locking tongues 76 with it in the direction of movement, i.e. in the direction away from the peripheral wall opening 66, until a positioning is reached in which the initially elastically deformed locking tongues 76 spring back and engage with their segments of the locking recess 80 on the locking projection 82.

A state is then reached in which, even if the first exhaust gas guide pipe 44 has not yet been secured to the peripheral wall 16 by welding, the first exhaust gas guide pipe 44 is held in a defined position in the direction of the pipe's longitudinal axis R on the retaining wall 46 and thus on the silencer 12 by locking. Here too, no deformation of the first exhaust gas guide pipe 44 or the retaining wall 46 is required for fastening the first exhaust gas guide pipe 44 to the retaining wall 46.

Subsequently, the first exhaust gas guide pipe 44 can be fixed to the peripheral wall 16 in the region of its first pipe end region 62 in the manner described above.

It should be noted that in this embodiment, the fastening edge region 60 on the retaining wall 46 could also be provided in such a way that, when the silencer insert 26 is surrounded by the peripheral wall 16, the fastening edge region 60 extends in the direction of the peripheral wall opening 66. In this case, the first exhaust gas guide pipe 44 can again be in one of the embodiments of the Fig. 3 and 4 corresponding manner in the area of its second pipe end area 64 in the retaining wall opening 58, but in such a way that the locking projection 82 is not yet positioned to engage in the locking recess 80. After the silencer insert 26, which is already provided with the first exhaust gas guide pipe 44, has been surrounded by the peripheral wall 16, the first exhaust gas guide pipe 44 can then be connected from the inside with its first Pipe end region 62 is moved in advance in the direction of the peripheral wall opening 16 and positioned so as to engage therein. During this process, the locking projection 82 also moves in the direction of the peripheral wall opening 66 and takes the locking tongues 76 with it until they lock into the segments of the locking recess 80 provided thereon on the locking projection 82. In this embodiment too, the locking tongue edge regions 78 and the fastening edge 60 on the holding wall 46 are therefore preferably bent in the direction in which the first exhaust gas guide pipe 44 is moved into the peripheral wall opening 66 when the first pipe end region 62 is moved.

The Fig. 9b ) shows a modification in which the locking projection 82 is not designed to run around the longitudinal pipe axis R in the circumferential direction, but rather comprises a plurality of locking projection segments 88 that follow one another in the circumferential direction. Accordingly, divided segments of the locking recess 80 could also be formed in the locking tongue edge areas, so that the first exhaust gas guide pipe 44 is also effectively locked to the retaining wall 46 in the circumferential direction. This can be advantageous if the first exhaust gas guide pipe 44 does not have a rotationally symmetrical design, but is to be positioned in a specific rotational position around the longitudinal pipe axis R with respect to the retaining wall 46.

Another variation is in Fig. 9c ). In this modification, the locking formation 84 on the first exhaust gas guide pipe 44 comprises two bead-like formations or locking projections 82, 82' provided thereby, which are spaced apart in the direction of the pipe's longitudinal axis R. A depression is formed between the two locking projections 82, 82', into which the retaining wall tongues 76 provided on the retaining wall 46 can be positioned so as to engage. Although this is not absolutely necessary, in this embodiment, a fastening edge region 60 surrounding the retaining wall opening 58 with retaining tongue edge regions 78 provided on the retaining tongues 76 can also be provided on the retaining wall 46, so that in this embodiment too Design form a planar contact interaction between the first exhaust gas guide pipe 44 and the retaining wall 46 is achieved.

Even in the Fig. 9c ), at least one of the locking projections 82 could not be provided by a bead-like formation running in the circumferential direction on the first exhaust gas guide pipe 44, but could be interrupted in the circumferential direction and, for example, be provided in the form of several segments.

It is further pointed out that the locking formation 84 could also be provided by a radially inwardly directed, bead-like indentation, possibly in the form of several segments following one another in the circumferential direction, which provides a locking recess open radially outward or several segments thereof. On the retaining wall, in the area of the retaining wall tongues, possibly in the area of the respective retaining wall tongue edge areas 78, a radially inwardly directed formation of the counter-locking formation 86 could be provided, each providing a locking projection, which can be positioned so as to engage in the locking recess provided on the second pipe end area 64 of the first exhaust gas guide pipe 44 when the first exhaust gas guide pipe 44 moves with respect to the retaining wall 46. This design can be particularly advantageous if the first exhaust gas guide pipe 44 is moved with its second pipe end region 64 first through the peripheral wall opening 66 and then into the retaining wall opening 58, since then such an oversize of the peripheral wall opening 66 that a locking projection on the first exhaust gas guide pipe 44 that protrudes radially outwards can also be guided through it is not necessary. The provision of such a locking recess on the first exhaust gas guide pipe 44 can, however, lead to a reduction in the flow cross-section of the first exhaust gas guide pipe 44 due to the bead-like formations directed radially inwards to provide it. The provision of the locking formation 84 by shaping the first exhaust gas guide pipe 44 radially outwards can therefore be considered advantageous in principle.

Finally, it should be noted that the design variants described above can be varied in various aspects. For example, more or fewer than the four wall interruption regions shown can be provided to form respective retaining wall tongues or locking tongues, and the wall interruption regions can, for example, have a greater extent in the circumferential direction, so that, for example, the circumferential extent of respective wall interruption regions can be greater than the circumferential extent of retaining wall tongues or locking tongues formed between two wall interruption regions.

Claims (19)

1. A method for producing an exhaust muffler, comprising the following measures:

   a) providing at least one muffler insert (26) with at least one retaining wall (46) and with at least one retaining-wall opening (58) in the at least one retaining wall (46),

   b) providing at least one first exhaust-gas routing pipe (44),

   c) surrounding the at least one muffler insert (26) with a peripheral wall (16) of a muffler housing (14), wherein a peripheral-wall opening (66) is provided in the peripheral wall (16), assigned to the at least one retaining-wall opening (58),

   d) arranging the at least one first exhaust-gas routing pipe (44) in such a manner that a first end region (62) of the at least one first exhaust-gas routing pipe (44) is positioned so as to engage in the peripheral-wall opening (66) provided, assigned to the at least one retaining-wall opening (58), and a second end region (64) of the at least one first exhaust-gas routing pipe (44) is retained in the at least one retaining-wall opening (58) by force closure or interlocking,

   e) connecting the at least one first exhaust-gas routing pipe (44) to the peripheral

   wall (16) by material closure in the region of the peripheral-wall opening (66), wherein in the course of measure a) the at least one first exhaust-gas routing pipe (44) is positioned so as to engage in the at least one retaining-wall opening (58), characterized in that in the course of measure d) the at least one first exhaust-gas routing pipe (44) is moved, with its first end region (62) leading, from inside in the direction toward the peripheral-wall opening (66) until the first end region (62) is positioned so as to engage in the peripheral-wall opening (66) and the second end region (64) is retained on the at least one retaining wall (46) by force closure or interlocking so as to engage in the at least one retaining-wall opening (58).
2. The method as claimed in claim 1, characterized in that in the course of measure a) the at least one muffler insert (26) is provided in such a manner that the at least one retaining wall (46) is connected to a partition (30, 32) in each of two opposite end regions (48, 50) of said wall,
   or/and
   in that the course of measure c) the at least one muffler insert (26) is surrounded with the peripheral wall (16) by winding of a plate-like peripheral-wall blank around the at least one muffler insert (26), or that in the course of measure c) the at least one muffler insert (26) is surrounded by providing the peripheral wall (16) with a structure that is closed in the peripheral direction and inserting the at least one muffler insert (26) into the peripheral wall (16) provided with a structure that is closed in the peripheral direction.
3. The method as claimed in one of claims 1 or 2, characterized in that a measure f) is provided for securing a front wall (22, 24) to each of the axial end regions (18, 20) of the peripheral wall (16), elongated in the direction of a longitudinal housing axis (L), by material closure or/and positive closure before or after implementation of measure c).
4. A muffler manufactured by a method according to one of claims 1-3, comprising:

   - a muffler housing (14) with a peripheral wall (16) elongated in the direction of a longitudinal housing axis (L) and with a front wall (22, 24) on each axial end region (18, 20) of the peripheral wall (16),

   - the muffler insert (26), surrounded by the peripheral wall (16) and supported on the peripheral wall (16), with at least one retaining wall (46) extending substantially in the direction of the longitudinal housing axis (L),

   - the at least one first exhaust-gas routing pipe (44), wherein the at least one first exhaust-gas routing pipe (44) is positioned with its first end region (62) engaging in the peripheral-wall opening (66) in the peripheral wall (16) and is secured to the peripheral wall (16) and retained with a second end region (64) on the at least one retaining wall (46).
5. The muffler as claimed in claim 4, characterized in that the at least one first exhaust-gas routing pipe (44) is connected to the peripheral wall (16) by welding, or/and in that the at least one first exhaust-gas routing pipe (44) is an inlet pipe.
6. The muffler as claimed in claim 4 or 5, characterized in that a retaining-wall opening (58), surrounded at least in some regions by a bent fastening-edge region (60) of the at least one retaining wall (46), is provided in the at least one retaining wall (46), assigned to the at least one first exhaust-gas routing pipe (44), and in that the at least one first exhaust-gas routing pipe (44) is positioned with its second end region (64) engaging in the retaining-wall opening (58) and is retained by press fit in the retaining-wall opening (58) in the region of the fastening-edge region (60), preferably wherein the fastening-edge region (66) is bent in the direction toward the first end region (62) of the at least one first exhaust-gas routing pipe (44), or wherein the fastening-edge region (60) is bent in the direction away from the first end region (62) of the at least one first exhaust-gas routing pipe (44).
7. The muffler as claimed in one of claims 4-6, characterized in that for the purpose of providing the force closure between the at least one first exhaust-gas routing pipe (44) and the at least one retaining wall (46) a completely circumferential abutting contact in the peripheral direction between the at least one first exhaust-gas routing pipe (44) and the at least one retaining wall (46) is provided in the region of the retaining-wall opening (58) provided on the at least one retaining wall (46), assigned to the at least one first exhaust-gas routing pipe (44),
   or
   in that
   for the purpose of providing the force closure between the at least one first exhaust-gas routing pipe (44) and the at least one retaining wall (46) an abutting contact, interrupted in at least one peripheral region, is provided between the at least one first exhaust-gas routing pipe (44) and the at least one retaining wall (46) in the region of the retaining-wall opening (58) provided on the at least one retaining wall (46), assigned to the at least one first exhaust-gas routing pipe (44), preferably wherein at least one preferentially slot-like wall-interruption region (70), preferentially a plurality of preferentially slot-like wall-interruption regions (70) arranged at a distance from one another around the retaining-wall opening (58) in the peripheral direction, open toward the retaining-wall opening (58), is/are provided in the at least one retaining wall (46) in the region of the retaining-wall opening (58) provided on the at least one retaining wall (46), assigned to the at least one first exhaust-gas routing pipe (44).
8. The muffler as claimed in claim 4 or 5, characterized in that a detent formation (84) is provided on the second end region of the at least one first exhaust-gas routing pipe (44), and in that a mating detent formation (86) in detent engagement with the detent formation (84) is provided on the at least one retaining wall (46), assigned to the detent formation (84).
9. The muffler as claimed in claim 8, characterized in that the detent formation (84) comprises at least one detent projection (82) protruding radially outward with respect to a longitudinal pipe axis (R) of the at least one first exhaust-gas routing pipe (44).
10. The muffler as claimed in claim 9, characterized in that the detent formation (84) comprises at least two detent projections (82, 82') succeeding one another in the direction of the longitudinal pipe axis (R), or/and in that the detent formation (84) comprises at least two detent-projection segments (88) succeeding one another around the longitudinal pipe axis (R) in the peripheral direction.
11. The muffler as claimed in claim 9 or 10, characterized in that at least one detent projection (82), preferentially each detent projection (82), is provided by a bead-like shaping of the at least one first exhaust-gas routing pipe (44).
12. The muffler as claimed in one of claims 8-11, characterized in that a retaining-wall opening (58) is provided in the at least one retaining wall (46), assigned to the at least one first exhaust-gas routing pipe (44), wherein a plurality of preferentially slot-like wall-interruption regions (70), arranged at a peripheral distance from one another around the retaining-wall opening (58) and open toward the retaining-wall opening, are provided in the at least one retaining wall (46), wherein a detent tongue (76) of the mating detent formation (86) is formed between at least two wall-interruption regions (70) immediately succeeding one another in the peripheral direction.
13. The muffler as claimed in claim 10 and claim 12, characterized in that at least one detent tongue (76), preferentially each detent tongue (76), of the mating detent formation (86) engages between two detent projections (82, 82') of the detent formation (84) succeeding one another in the direction of the longitudinal pipe axis.
14. The muffler as claimed in claim 9 and claim 12 or 13, characterized in that a detent recess (80) for receiving at least one detent projection (82) of the detent formation (84) is provided on at least one detent tongue (76), preferentially on each detent tongue (76).
15. The muffler as claimed in one of claims 12-14, characterized in that a bent detent-tongue edge region (78) is provided on the at least one retaining wall (46) near at least one detent tongue (76), preferentially near each detent tongue (76).
16. The muffler as claimed in claim 13 and claim 15, characterized in that at least one detent-tongue edge region (78), preferentially each detent-tongue edge region (78), engages between two detent projections (82, 82') of the detent formation (84) succeeding one another in the direction of the longitudinal pipe axis (R).
17. The muffler as claimed in claim 14 and claim 15, characterized in that at least one detent recess (80) is provided on at least one detent-tongue edge region (78), preferentially on each detent-tongue edge region (78).
18. The muffler as claimed in one of claims 4-17, characterized in that the muffler insert (26) includes at least two partitions (28, 30, 32, 34) arranged so as to be substantially orthogonal to the longitudinal housing axis (L) and supported on said peripheral wall (16), wherein the at least one retaining wall (46) is secured to one of the partitions (28, 30, 32, 34) in each of two opposite end regions (48, 50) of said wall, preferably wherein the muffler insert (26) includes at least one second exhaust-gas routing pipe (52, 54), preferentially an outlet pipe, wherein a partition opening is provided in at least one of the partitions (30, 32) connected to the at least one retaining wall (46), assigned to the at least one second exhaust-gas routing pipe (52, 54), and a front-wall opening is provided in one of the front walls (22, 24), wherein the at least one second exhaust-gas routing pipe (52, 54) is positioned so as to engage in the partition opening and in the front-wall opening and is secured by material closure in the region of the front-wall opening to the front wall (22, 24) exhibiting said opening or/and in the region of at least one partition opening to the partition exhibiting said opening.
19. An exhaust system for an internal-combustion engine, comprising at least one muffler (12) as claimed in one of claims 4-18, manufactured according to the method as claimed in one of claims 1-3.