EP3032063A1 - Exhaust pipe - Google Patents

Abstract

The present invention relates to an exhaust-carrying pipe (11) of an exhaust system (1) of an internal combustion engine (9), with an exhaust gas pipe body (15) and at least one with respect to the tubular body (15) separate attachment (12) laterally to the Tubular body (15) is mounted so that outside of the tubular body (15) at least partially by the attachment (12) limited cavity (13) is arranged extending in the circumferential direction (14) of the tubular body (15) over less than 360 ° , The tubular body serves as a stiffening element and as a muffler, which acts as a closed resonance chamber via perforations in the exhaust gas pipe (11).

Description

The present invention relates to an exhaust pipe leading an exhaust system of an internal combustion engine. The invention also relates to an exhaust system equipped with at least one such pipe.

An exhaust system, which serves to remove combustion exhaust gases from an internal combustion engine, fulfills a number of functions. The most important functions are, on the one hand, the implementation of exhaust gas aftertreatment in order to reduce the pollutant emissions of the internal combustion engine. On the other hand, the exhaust system causes an intensive sound attenuation to reduce the noise emissions of the internal combustion engine. Silencers with a small damping volume can be positioned virtually anywhere along the exhaust system and acoustically connect with a pipe of the exhaust system leading to exhaust gas. For example, a tubular housing of such a silencer can be arranged concentrically to such an exhaust pipe and connected thereto via end-side end floors. A perforation in the exhaust pipe then leads to the acoustic coupling between the exhaust system, ie the interior of the exhaust pipe and a damping chamber formed in the housing, which surrounds the exhaust pipe annular. The problem with such simple mufflers, however, is the different thermal load of the exhaust pipe on the one hand and the tubular housing on the other. In general, the exhaust pipe is exposed to significantly higher temperature fluctuations than the housing, so that the connection points between the housing and the exhaust pipe, which are located on the front end of the housing, are exposed to high thermal cycling. To solve this problem is basically conceivable to interrupt the exhaust pipe within the housing, ie between two end floors, which fix the housing on the exhaust pipe, or equip it with a sliding seat, so that ultimately the housing is kept movable in the longitudinal direction of the exhaust pipe relative to the exhaust pipe. However, such a design is relatively expensive. In addition, problems with gas tightness may occur.

The exhaust pipes used in the exhaust system can also contribute to the stability of the exhaust system, for example, if about such an exhaust pipe two relatively heavy components of the exhaust system must be connected to each other.

The present invention is concerned with the problem of providing for an exhaust pipe leading the above type or for an exhaust system equipped therewith an improved embodiment, which is characterized in particular by an additional function. In particular, according to one aspect of the invention, an increased dimensional stability or rigidity is sought for the exhaust pipe. According to a further aspect of the invention, a particularly inexpensive manufacturability of a silencer may be desired. As an additional aspect, a compact design for the exhaust pipe with muffler function may also be desired.

The problem of the invention is solved by the subject matter of the independent claim. Advantageous embodiments are the subject of the dependent claims.

The invention is based on the general idea to equip the exhaust gas pipe, which is also referred to below as the exhaust pipe, with a respect to a tubular body of the exhaust pipe separately manufactured attachment, wherein the attachment is externally attached to the tubular body, such that outside the tubular body creates a cavity which is completely or partially delimited by the attachment. Furthermore, the attachment and tube body are coordinated so that the attachment extends in the circumferential direction of the tubular body over less than 360 ° and preferably over 180 ° or less than 180 °. By attaching the attachment to the tubular body, the exhaust pipe is stiffened in the region of the attachment. Since the attachment is designed or arranged on the tubular body, that forms a cavity in addition to the exhaust gas leading interior of the tubular body, results transversely to the longitudinal direction of the tubular body, an increased area moment of inertia, which significantly increases the rigidity of the exhaust pipe. The provision of the cavity also provides the ability to use the cavity as a sound attenuation space, whereby the exhaust pipe can be modified to a silencer. Such a silencer can be realized relatively inexpensively, since essentially only the attachment to the pipe body of the exhaust pipe must be mounted. The arrangement of the attachment to the exhaust pipe, such that the attachment extends a maximum of half the circumference of the tubular body, also leads to an extremely compact design, so that the exhaust pipe presented here virtually at any point of the exhaust system between the beginning, the is usually formed by an exhaust manifold, and their end, which is usually formed by a tailpipe, realize.

For example, it can thus be provided that the cavity is closed to the outside. In addition, it can be provided that the cavity is fluidically and / or acoustically connected to an interior of the tubular body. Furthermore, it can optionally be provided that the cavity is filled with sound-absorbing material.

According to an advantageous embodiment, the attachment may be attached to two opposite sides of the tubular body on the tubular body. The attachment extends along the longitudinal direction of the tubular body, so that the attachment of the attachment to the tubular body in cross-section of the tubular body takes place on two opposite sides and preferably on two diametrically opposite sides. The direct coupling of the attachment to the tubular body, in particular a good thermal coupling between attachment and tubular body is achieved, so that the temperature difference between the tubular body and fixture is reduced. As a result, also thermally induced stresses between fixture and tubular body are reduced.

According to a particularly advantageous development, the attachment can be fixed on the respective side of the tubular body by means of a welded connection to the tubular body, which extends in the longitudinal direction of the tubular body along the tubular body. Since the fixation between attachment and tubular body thus takes place along the longitudinal direction of the tubular body, thermally induced expansion differences only lead to comparatively low stresses within the weld, since this is only loaded in its longitudinal direction. An embodiment in which the respective welded connection extends over the entire length of the attachment is advantageous. As a result, the thermal cycling of the respective weld is minimized.

In another advantageous embodiment, the attachment may be a shell body made of one piece, which has a U-shaped cross-section and two leg connected via an arc transversely to a longitudinal extent of the exhaust pipe end of the tubular body, which are attached to opposite sides of the tubular body. The design of the attachment as a shell body allows a particularly inexpensive feasibility of the attachment and the exhaust pipe equipped therewith. The cavity is then limited on the one hand by an inner wall of the attachment and on the other hand by an outer wall of the tubular body.

According to an advantageous development of the tubular body may be perforated in the region of the attachment. Such a perforation can in principle be configured in any desired manner, for example by a single wall opening or preferably by a multiplicity, comparatively smaller wall openings. Through the perforation, an acoustic coupling of the tube interior with the cavity, whereby the cavity can be used as Schalldämpfungsraum. For example, the cavity serves as an expansion chamber or as an absorption chamber. With specific tuning of the perforation or the openings of the perforation and a kind of Helmholtz resonator can be realized, the resonance volume is limited by the cavity and the vibration volume is formed within the openings of the perforation. In principle, a "genuine" Helmholtz resonator can also be realized if a so-called "neck" containing the oscillatory volume is provided in a suitable manner. For example, such a neck of the Helmholtz resonator can be generated by a branch pipe branching from the pipe body within the attachment, by a corresponding geometry of the attachment or by an exhibition or Austulpung of the tubular body when producing a wall opening in the tubular body. Likewise, a sound attenuation can be realized by means of micro perforation, if the openings of the perforation have an opening cross section of a maximum of 1 mm.

In an alternative embodiment, the attachment may be a one-piece further or other tubular body having a port side that is complementarily shaped to an outer wall of the exhaust-carrying tubular body to which the additional tubular body is mounted such that the port side contacted the outer wall areally. Due to the surface contact between the outside and the outer wall, an intense heat transfer between the attachment and tubular body can be realized, which reduces thermally induced stresses due to temperature differences. In this design, the cavity is limited at least in the cross section of the exhaust pipe exclusively by an inner side of the attachment. This allows a shaping of the cavity independently of the exhaust gas pipe body.

According to an advantageous development, the connection side of the attachment part and the outer wall of the exhaust-gas-conducting tubular body can be perforated in the region of the contact between the connection side and outer wall. This also creates an acoustic coupling between the interior of the tubular body through which exhaust gas flows and the cavity of the attachment not throughflow, in order to realize a sound damping function. The perforations of connection side and outer wall can basically be configured identically. It is also possible to design the perforations differently. For example, the outer wall of the tube may be formed with a perforation formed by a plurality of openings, while the connection side has a perforation formed by a single opening which extends over all the openings of the perforation of the outer wall. Likewise, a reverse design is conceivable.

According to another advantageous embodiment, the cavity can be closed in the longitudinal extension of the tubular body at each end by a closure element. Such a closure at the longitudinal ends of the cavity is especially necessary when the respective cavity is acoustically and ultimately also fluidically coupled to the interior of the tubular body. The respective closure element can in principle represent a separate component with respect to the attachment, which attaches to the attachment in a suitable manner is. It is also conceivable to form the respective closure element integrally on the attachment. Furthermore, it is conceivable to fasten the respective closure element to the tubular body. It is also conceivable to form at least one such closure element integrally on the tubular body.

The exhaust pipe leading body can basically have any spatial length. For example, it may extend arcuately or rectilinearly.

If the tube body extends in a straight line or has a straight section, it is conceivable to arrange at least two such attachments on the tube body, which are arranged offset in the circumferential direction of the tube body and / or in the longitudinal direction of the tube body to each other on the tube body. In this way, the space available along the exhaust system can be exploited particularly favorably to provide a stiffening and / or a silencing function by attaching a plurality of such attachments to the respective exhaust pipe.

In another advantageous embodiment, the tubular body may extend curved so that it has a bow. Appropriately, the attachment is then arranged on an inner side of the sheet on the tubular body. In this way, a particularly efficient stiffening of the curved tubular body results in the region of the arc.

According to a development, the attachment can be shaped so that the cavity is closed in the longitudinal extension of the tubular body at each end by the tubular body itself, even if this no additional closure elements are formed on the attachment. In this case, the attachment is adapted to the curvature or to the arc of the tubular body that the Cavity is closed on all sides, when the attachment is attached to the pipe body. This measure also simplifies the production of the exhaust pipe presented here with attachment and cavity.

This embodiment can be particularly well combined with the embodiment described above, in which the attachment is a one-piece shell body having a U-shaped cross-section with two legs connected via a bow transversely to a longitudinal extent of the tubular body at opposite Side of the tubular body are attached. Particularly advantageous is an embodiment in which the two legs are curved in each case at its edge remote from the arc of the shell body according to the arc of the tubular body. Since, in addition, the optionally existing weld follows this edge, there is a significant stiffening of the tubular body in the region of its arc.

An exhaust gas system according to the invention comprises at least one exhaust aftertreatment device, which may be configured, for example, as a catalytic converter or as a particle filter or as a silencer or as any desired combination of such components. In any case, the exhaust aftertreatment device or its housing is connected on the inlet side and the outlet side in each case to an exhaust pipe leading piece of pipe. In the exhaust system according to the invention is now formed at least in such a piece of pipe through an exhaust pipe of the type described above, which is characterized by an additional function, namely by an increased stiffness and optionally by a silencing function.

Other important features and advantages of the invention will become apparent from the dependent claims, from the drawings and from the associated figure description with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components.

Fig. 1

eine stark vereinfachte, schaltplanartige Prinzipdarstellung einer Abgasanlage mit mehreren Abgasrohren,

Fig. 2

ein stark vereinfachter Querschnitt eines Abgasrohrs, entsprechend Schnittlinien II in Fig. 1,

Fig. 3

ein Querschnitt wie in Fig. 2, jedoch bei einer anderen Ausführungsform,

Fig. 4

ein Längsschnitt des Abgasrohrs entsprechend Schnittlinien IV in Fig. 2,

Fig. 5

mehrere Seitenansichten von Abgasrohren bei verschiedenen Ausführungsformen a bis e,

Fig. 6

isometrische Ansichten der Abgasrohre aus Fig. 5 bei den verschiedenen Ausführungsformen a bis e.

Show, in each case schematically,

Fig. 1

a greatly simplified schematic diagram of an exhaust system with several exhaust pipes,

Fig. 2

a greatly simplified cross section of an exhaust pipe, corresponding to section lines II in Fig. 1 .

Fig. 3

a cross section as in Fig. 2 but in another embodiment,

Fig. 4

a longitudinal section of the exhaust pipe according to section lines IV in Fig. 2 .

Fig. 5

several side views of exhaust pipes in various embodiments a to e,

Fig. 6

isometric views of the exhaust pipes off Fig. 5 in the various embodiments a to e.

Corresponding Fig. 1 In addition, the exhaust system 1 has a plurality of pipe sections 5, for example, to connect two exhaust aftertreatment devices 2 with each other or to connect the exhaust manifold 3 with such an exhaust aftertreatment device 2. Die Abgasaustrennung 3 bzw. The exhaust aftertreatment devices 2 may be, for example, a catalytic converter 6, a particulate filter 7 and a silencer 8. Appropriately, in each case a housing 35 of the respective exhaust aftertreatment device 2 is connected to such a pipe section 5 on the inlet side and / or outlet side. In the example of Fig. 1 is directly connected to the silencer 8, the tailpipe 4.

The exhaust system 1 is used for discharging combustion exhaust gases from an internal combustion engine 9, which is also equipped for fresh air supply with a fresh air system 10. Conveniently, internal combustion engine 9, exhaust system 1 and fresh air system 10 are arranged in a motor vehicle not shown here.

In the example of Fig. 1 are two of the pipe sections 5 as the exhaust pipe leading 11, which may also be referred to below as the exhaust pipe 11, designed as follows. According to the Fig. 1 to 6 such an exhaust pipe 11 comprises a pipe section 15, which serves to guide an exhaust gas flow during operation of the exhaust system 1, and an attachment 12, which is not traversed by exhaust gas during operation of the exhaust system 1, which is a separate component with respect to the tubular body 15 and the the tubular body 15 is grown. In this case, a geometry of the attachment 12 and its arrangement on the tubular body 15 are coordinated so that outside of the tubular body 15, a cavity 13 is formed, which is at least partially bounded by the attachment 12.

How in particular the Fig. 2 to 6 can be seen extending the attachment 12 and the cavity 13 in a circumferential direction 14 of the tubular body 15 is not complete, that is less than 360 ° and preferably over 180 ° along the tubular body 15 of the exhaust pipe 11. The tubular body 15 performs the exhaust gas leading function the exhaust pipe 11 and can therefore be referred to as a flow-through or exhaust pipe leading body 15.

How in particular the Fig. 2 and 3 can be seen, the attachment 12 is attached to two opposite sides of the tubular body 15 on the tubular body 15. Are recognizable in the Fig. 2 and 3 two welds 16 each, which fix the attachment 12 on the tubular body 15. It is particularly advantageous if the respective weld 16, which can also be generally referred to as welded joint 16, extends in a longitudinal direction 17 or longitudinal extent 17 of the tubular body 15 along the tubular body 15. The longitudinal direction 17 or the longitudinal extent 17 of the tubular body 15 follows a longitudinal central axis 18 of the tubular body 15, which according to the examples of Fig. 4 and 5a to 5d such as 6a to 6d rectilinear or according to the example of Fig. 5e and 6e can be curved. In particular, the respective welded connection 16 can extend over the entire length of the attachment 12 in the longitudinal direction 17 along the tubular body 15.

According to the in the Fig. 2 and 4 embodiment shown, the attachment 12 may be a shell body 19, which is made in one piece, so in one piece. The shell body 19 is provided transversely to the longitudinal extent 17 of the tubular body 15 with a substantially U-shaped cross section, in which two legs 20 are connected to each other via a sheet 21. The opposing legs 20 are attached to opposite sides of the tubular body 15. Furthermore, in the preferred example shown here, the tubular body 15 perforated in the region of the attachment 12, that is equipped with a perforation 22, which is formed purely by way of example by a plurality of separate openings 23. As a result, an inner space 24 of the tubular body 15 is acoustically and ultimately also fluidically coupled to the cavity 13. The cavity 13 is not flowed through by the exhaust gas. The cavity 13 thus serves as a sound damping chamber, for example as an absorption chamber or as a reflection chamber. According to Fig. 4 can be arranged in the cavity 13, a sound-absorbing material 25, for example, metal wool or the like.

According to Fig. 3 the attachment 12 may be configured instead of a shell body 19 alternatively as a further tubular body 26, which is also suitably made in one piece or in one piece. This further tubular body 26 is not traversed by exhaust gas in contrast to the exhaust-carrying tubular body 15 and has a connection side 27 which is shaped to be complementary to an outer wall 28 of the exhaust-carrying tubular body 15. With this complementary connection side 27 of the further tubular body 26 is attached to the outer wall 28 of the exhaust pipe tube body 15, such that the connection side 27 rests flat against the outer wall 28. As a result, an intensive heat transfer between the exhaust gas pipe body 15 and the further tubular body 26 of the fixture 12 is achieved. In the example of Fig. 3 is also a sound damping function for the exhaust pipe 11 is provided. For this purpose, the connection side 27 and the outer wall 28 are perforated in the region of the contact between the outer side 27 and the outer wall 28. By way of example, the exhaust pipe leading body 15 is again provided with a perforation 22 which is formed by a plurality of openings 23. In contrast, a perforation 29 of the further tubular body 26 is formed purely by way of example by a single opening 30 which covers the entire region of the perforation 22 of the tubular body 15 carrying exhaust gas. It is also conceivable to provide such a window-like opening in the exhaust gas-carrying tubular body 15, while then the further tubular body 26 a Having formed by a plurality of openings perforation. However, the aforementioned variant is preferred because of the reduced flow resistance. Again, an acoustic and ultimately fluidic coupling between the in the cavity 13 and the interior 24 is created by the perforations 22, 29.

According to Fig. 4 can the cavity 13 in the longitudinal extension 17 of the tube 11 and the exhaust gas pipe body 15 are closed at each of its longitudinal ends or front ends in each case by a closure element 31. As a result, the shape of the attachment 12. If no perforation 22 is provided, such closure elements 31 are basically not required to achieve the desired stiffening of the exhaust pipe body 15 and the exhaust pipe 11. However, if the cavity 13 are to be used for soundproofing, the cavity 13 must be sealed tight on all sides, except for the area of the perforation 22. In the example of Fig. 4 the two closure elements 31 are designed both as regards the exhaust-carrying tubular body 15 and with respect to the attachment 12 as separate components, which are grown both to the attachment 12 and to the tubular body 15. However, corresponding welds or welds are not shown here. Likewise, it is conceivable in principle that respective closure elements 31 form integrally on the tubular body 15 or integrally on the attachment 12.

Referring to the FIGS. 5 and 6 Now further basic features for other embodiments are discussed, wherein the features explained below can in principle also be combined as desired with the features of the embodiments explained above.

According to variants a to d of FIGS. 5 and 6 the exhaust pipe 11 is generally straight. Its tubular body 15 thus extends straight. In the embodiments a to c of FIGS. 5 and 6 In each case two attachments 12 are attached to the tubular body 15. In the embodiment a of FIGS. 5 and 6 the two attachments 12 in the longitudinal direction 17 of the tubular body 15 are mutually offset on the tubular body 15. In variants a and b of FIGS. 5 and 6 are the two attachments 12 diametrically opposite, that is offset by 180 ° in the circumferential direction 14 to each other on the tubular body 15. This makes it possible in particular to fix the two attachments 12 via common welds 16 on the tubular body 15.

In the embodiments a, b and c of FIGS. 5 and 6 are the attachments 12 in the longitudinal direction 17 each sized the same size. In principle, it is also conceivable to dimension the two attachment parts 12 unevenly.

The embodiment c of FIGS. 5 and 6 differs from the embodiment b of the FIGS. 5 and 6 in that the two attachments 12 are not exactly diametrically opposed, but are aligned at a different angle from 180 ° to each other. This can be advantageous for adapting the exhaust pipe 11 to special installation situations.

The attachments 12 can be attached as explained exclusively for stiffening purposes on the tubular body 15. This stiffening is particularly efficient if, with the help of the attachment 12, said cavity 13 is provided outside the exhaust pipe body 15 leading, since this significantly increases the area moment of inertia of the entire exhaust pipe 11. However, the embodiment is preferred in which the cavity 13 is used as a sound-damping chamber, so that an acoustic coupling between the interior 24 of the tubular body 15 and the cavity 13 is made. For this the must Cavity 13 to be close to an environment 32 of the exhaust pipe 11. As above Fig. 4 explained, the closure elements 31 may be provided for this purpose. However, these closure elements 31 are in Fig. 6a to d not shown.

According to the variant e of FIGS. 5 and 6 can the exhaust pipe 11 and its tubular body 15 extend curved so that the tubular body 15 has a bow 33. The attachment 12 is now preferably arranged on an inner side 34 of the sheet 33 on the tubular body 15. As a result, the curved tube 11 can stiffen particularly efficient. In addition, the attachment 12 according to the Fig. 5e and 6e each specifically be shaped so that the cavity 13 is closed at its longitudinal ends in each case by the tubular body 15 directly. This can be realized particularly easily when the attachment 12 is configured as a shell body 19. Separate or additional closure elements 31 can thus be dispensed with. Recognizable possess in this side view then the two legs 20 of the U-shaped shell body 19 each have a distance from the rectilinear arc 21 of the shell body 19 edge along which the weld 16 extends. Said edge has a curvature which corresponds to the curvature of the arc 33 of the tubular body 15, that is, has substantially the same radius of curvature.

Claims (15)

Exhaust gas pipe (11) of an exhaust system (1) of an internal combustion engine (9), with an exhaust gas pipe body (15) and with at least one with respect to the tubular body (15) separate attachment (12) laterally to the tubular body (15) so is mounted, that on the outside of the tubular body (15) at least partially by the attachment (12) limited cavity (13) is arranged, which extends in the circumferential direction (14) of the tubular body (15) over less than 360 °. Pipe according to claim 1,
characterized,
that the cavity (13) is closed to the outside. Pipe according to claim 2,
characterized,
that the cavity (13) having an interior (24) of the tubular body (15) is fluidically and / or acoustically connected. Pipe according to claim 2 or 3,
characterized,
that the cavity (13) with sound-absorbing material (25) is filled. Pipe according to one of claims 1 to 4,
characterized, - that the attachment (12) on two opposite sides of the tubular body (15) is fixed to the tube body (15), - That the attachment (12) on the respective side of the tubular body (15) by means of a welded joint (16) is fixed to the tubular body (15) extending in the longitudinal extent (17) of the tubular body (15) along the tubular body (15) , Pipe according to one of claims 1 to 5,
characterized,
that the attachment part (12) is made of one piece shell body (19) transversely to a longitudinal extension (17) of the tubular body (15) has a U-shaped cross-section with two through an arc (21) connected to the legs (20), which are fixed to opposite sides of the tubular body (15). Pipe according to claim 6,
characterized,
that the tubular body (15) is perforated in the area of the attachment part (12). Pipe according to one of claims 1 to 5,
characterized,
in that the attachment part (12) is a further tube body (26) produced in one piece, which has a connection side (27) which is shaped complementarily to an outer wall (28) of the tube body (15) carrying exhaust gas, to which the further tube body ( 26) is attached, so that the connection side (27) and the outer wall (28) lie flat against each other. Pipe according to claim 8,
characterized,
in that the connection side (27) and the outer wall (28) are perforated in the region of the contact between the connection side (27) and outer wall (28). Pipe according to claim 7 or 9,
characterized,
that a perforation (22) of the tubular body (15) having a plurality of openings (23) which are adjacent to one another axially and / or in the circumferential direction (14) of the tubular body (15). Pipe according to one of claims 1 to 10,
characterized,
that the cavity (13) in the longitudinal extension (17) of the tubular body (15) is closed at each end by a closure element (31). Pipe according to claim 11,
characterized, - That at least one such closure element (31) on the tubular body (15) is attached, and / or - That at least one such closure element (31) attached to the attachment (12) or integrally formed thereon. Pipe according to one of claims 1 to 12,
characterized, that the tubular body (15) extends in a straight line, - That at least two such attachments (12) are attached to the tubular body (15) in the circumferential direction (14) of the tubular body (15) and / or in the longitudinal direction (17) of the tubular body (15) offset from each other on the tubular body (15 ) are arranged. Pipe according to one of claims 1 to 12,
characterized, in that the tubular body (15) extends in a curved manner and has an arc (33), the attachment (12) being arranged on an inner side (34) of the arc (33) on the tubular body (15), - That the attachment (12) is shaped so that the cavity (13) in the longitudinal extension (17) of the tubular body (15) is closed at each end by the tubular body (15) itself, - That the attachment (12) is a one-piece shell body (19) which transversely to a longitudinal extent (17) of the tubular body (15) has a U-shaped cross-section with two via a sheet (21) connected legs (20) mounted on opposite sides of the tubular body (15), - That the two legs (20) in each case at its from the arc (21) of the shell body (19) remote edge corresponding to the arc (33) of the tubular body (15) are curved. Exhaust system of an internal combustion engine (9), which has at least one exhaust aftertreatment device (2) which is connected on the inlet side and outlet side respectively to a exhaust pipe piece (5), wherein at least one such pipe piece (5) by an exhaust pipe (11) according to one of the preceding Claims is formed.

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