EP3311009A1

EP3311009A1 - Exhaust-gas system

Info

Publication number: EP3311009A1
Application number: EP16726078.5A
Authority: EP
Inventors: Rainer Drees; Christian Eichmüller
Original assignee: Bayerische Motoren Werke AG
Current assignee: Bayerische Motoren Werke AG
Priority date: 2015-06-22
Filing date: 2016-05-30
Publication date: 2018-04-25
Anticipated expiration: 2036-05-30
Also published as: WO2016206915A1; CN107429585B; DE102015211460A1; US10746065B2; EP3311009B1; US20180016954A1; CN107429585A

Abstract

The invention relates to an exhaust-gas system for a vehicle having an internal combustion engine, comprising a Helmholtz resonator (2) and two exhaust-gas lines (3) extending toward the resonator, wherein the resonator (2) has two neck openings (7) to a resonator volume (4), each neck opening (7) is coupled to one of the exhaust-gas lines (3), and the resonator (2) is tuned to damp a dominating engine order.

Description

exhaust system

description

The present invention relates to an exhaust system for a vehicle having an internal combustion engine, with a Helmholtz resonator and two extending in the direction of the resonator exhaust pipes, according to the preamble of claim 1. Exhaust systems for multi-cylinder, powerful internal combustion engines are usually provided with two separate exhaust pipes, for example, emanating from a respective cylinder bank of a V-engine or, for example, each of two or three cylinders of a multi-cylinder in-line engine.

The configuration with separate exhaust pipes has the advantage over a single exhaust pipe with a large single cross-section, that it is easier to lay for the sake of the available space in a vehicle and still provides sufficiently large cross-sections to the exhaust pipe.

In the exhaust pipes in addition to a common or separate exhaust catalysts other components for reducing the combustion-related noise emissions of the engine are installed, such as pre-muffler, center muffler or rear muffler and finally, the exhaust pipes also have respective tailpipes or Abgasauslassmündungen. It is also already known, in the housing of the rear silencer or connected to a branch line with the rear silencer specifically tuned Helmholtz resonators or λ / 4 provide attenuator, which are each tuned to a speed range of the engine, in which the internal combustion engine to conspicuous, the Comfort specifications for the vehicle not corresponding drone frequencies tends. With these, the noise emissions of the internal combustion engine influencing facilities intended targeted the muzzle level at the exhaust outlet or the exhaust gas outlet ports are reduced.

A multi-stage Helmholtz resonator is known from DE 200 03 666 U1, in which the resonator volume can be increased or reduced via a switchable flap provided in the resonator housing, whereby a sound level reduction of two different main frequencies can be achieved.

An exhaust system for a vehicle is known from DE 100 84 870 T1, which has a silencer which is coupled via a branch line to a Helmholtz resonator which is formed by an independent resonator housing, which is arranged on the vehicle underbody and from Exhaust gas is not flowed through and is formed from a polymer.

It is also already known to provide switchable exhaust valves in the exhaust system, which further reduce the noise emissions with the flap closed by a consequent reduction of the exhaust gas flowable through the cross section of the exhaust pipes, said measures but regularly increase the pressure prevailing in the exhaust system exhaust back pressure and thus deteriorate the experience of the driver of the vehicle responsiveness of the engine and increase the fuel consumption of the engine due to the exhaust gas to be provided by the engine against the high exhaust backpressure.

Based on this, the present invention, the object of a To provide exhaust system for a vehicle with an internal combustion engine, which allows a reduction in the noise emissions of the internal combustion engine, but without generating a high exhaust back pressure. It is also intended to provide a method for operating an exhaust system of an internal combustion engine.

To solve this problem with regard to the exhaust system, the invention has the features specified in claim 1. Advantageous embodiments thereof are described in the further claims.

In addition, the invention has the features specified in claim 13 with respect to the method.

The invention provides an exhaust system for a vehicle having an internal combustion engine, with a Helmholtz resonator and two extending in the direction of the resonator exhaust pipes, wherein the resonator has two neck openings to a resonator volume and a respective neck opening is coupled to a respective exhaust pipe and the Resonator for damping a dominant engine order is tuned.

The invention takes into account the cramped space available on a vehicle for silencing regularly and sees instead of the use of the silencer volume for integration of damping components that allow sound absorption by the reflection method or absorption method, the formation of a Helmholtz resonator in a possible silencer volume exploiting housing before, wherein the resonator volume is coupled by means of a respective neck opening with a respective exhaust pipe of the twin-flow exhaust system. The exhaust system accordingly has two exhaust pipes, which are provided for the conduction of exhaust gas from the internal combustion engine in the direction of the exhaust gas outlet and each exhaust pipe is by means of a respective neck opening or branch line with which the resonator volume of the Helmholtz Resonator forming housing coupled and the Helmholtz resonator is tuned for damping at least one specific for the engine engine order. In this case, the engine order may be that which makes the greatest contribution to the orifice level in terms of amount, so that the resonator can be tuned to the frequency which contributes the highest sound pressure level to a measured orifice level. For example, the resonator can be tuned exactly to the frequency that gives the highest level in a type approval approval drive. This orifice level may thus be, for example, the orifice level relevant to a vehicle type approval of the vehicle during an approval run, which is then reduced by the resonator to an allowable measured sound pressure level without the need for sound attenuation devices operating according to the reflection or absorption techniques. Due to the lack of sound damping devices that operate on the reflection method or the absorption process, also eliminates the disadvantage of increasing the exhaust backpressure in the exhaust system.

According to a development of the invention, it is provided that the resonator has a housing having the resonator volume, which housing is formed separately from other component housings of the exhaust system and the housing is arranged at a distance from the rear area of the vehicle. By means of this configuration it is achieved that a space as large as possible is used for noise reduction measures on the vehicle, as large a resonator volume as possible is used, and the resonator housing is arranged at a large distance from the rear of the vehicle, whereby a component having a rigid structure, namely, the housing required for soundproofing is taken out of the region of the rear structure of the vehicle, and if the rear of the vehicle is damaged by the rigid component, components which are no longer adjacent to the vehicle are damaged by the rigid component.

It is also provided according to a development of the invention that the exhaust gas Anläge has a respective, arranged in the region between the exhaust pipe and the resonator volume flap, which is designed for at least partially releasing and / or closing the respective neck opening. With these flaps arranged adjacent to the resonator volume, the Helmholtz resonator can, as it were, be switched on or off, it is thus possible to influence the sound level at the exhaust gas outlet openings of the exhaust pipes, and it is also possible to reduce the attenuation level of the exhaust pipe by only partially releasing the neck openings Resonator set variable. It does not change the resonance frequency of the damping, but only the degree of damping according to the opening angle of the flaps or resonator flaps.

The flaps can be opened and / or closed, for example, in an elevation-selective or gangway-selective or driving-mode-selective manner, the flaps can be opened, for example, in a certain speed range of the vehicle, so that the Helmholtz resonator reduces the orifice level while the flaps in another Speed range of the vehicle or, for example, in a sport driving mode of the vehicle are closed and therefore the muzzle level is higher. It is also provided according to a development of the invention that each exhaust pipe in the flow direction of the exhaust pipes downstream of the resonator has at least two Abgasauslaßmündungen and at least one respective Abgasauslaßmündung is provided with an exhaust flap, by means of which the exhaust gas outlet opening is reversibly closed.

In other words, this means that a respective exhaust pipe has two exhaust gas outlet openings, ie four exhaust gas outlet openings are provided in the case of two exhaust pipes, wherein in each case an exhaust gas outlet opening of an exhaust gas outlet orifice pair is provided with an exhaust gas flap which can be controlled separately from the resonator flaps.

By means of the exhaust flap, the respective exhaust outlet can be closed, thereby further influencing the noise emissions of the vehicle is possible, it can be counteracted with the exhaust valves, for example, while driving the comfort of the vehicle-reducing noise emissions, which may occur, for example, in overrun operation of the vehicle. The fact that the exhaust valves are controlled independently of the resonator flaps, an influence on the noise emissions of the vehicle over a wide range of applications is possible.

It is also provided according to a development of the invention that the common cross section of the exhaust gas outlet openings per exhaust pipe is the same size as the cross section of the relevant exhaust pipe. In other words, this means that the sum cross section of the exhaust gas outlet openings of an exhaust pipe is larger than the cross section of this exhaust pipe. In this way, it is achieved that the flow resistance which occurs in the region of the exhaust gas outlet openings and which counteracts the exhaust gas flow is not greater than the flow resistance in the exhaust pipe, as is the case with known exhaust systems.

As a result, it is also possible to achieve a reduction in the exhaust emissions, since the internal combustion engine does not have to provide increased exhaust work for discharging the exhaust gases at high exhaust counterpressure. The reduction of the flow cross-section of the exhaust gas outlet orifices necessary for reducing the acoustic emissions in known exhaust systems can therefore be dispensed with in the exhaust system according to the invention.

According to a development of the invention, it is also provided that the exhaust systems have a device for the common control of the valve arranged between the resonator volume and the respective exhaust pipe. This device can be part of the engine control and control both resonator flaps together, whereby the cost of providing signal lines or Ansteuerleitungen is reduced to the Resonatorklappen the vehicle.

It is also provided according to a development of the invention that the exhaust system comprises a device for the common control of the in a respective Ab- Has gas outlet mouth arranged exhaust flap. This device can also be part of the engine control and control the exhaust valves together, which in turn reduces the number of signal lines or Ansteuerungsleitun- gene to the exhaust valves on the vehicle.

It is also provided according to a development of the invention that the exhaust system has a provided in the flow direction of the exhaust pipes downstream of the resonator means for sound damping. This device for soundproofing may be, for example, a rear muffler which receives the exhaust port of the respective exhaust pipe and with which the vehicle-specific sound spectrum can be influenced.

According to a development of the invention, it is also provided that the resonator volume is divided into at least two partial volumes by means of a dividing wall. The sub-volumes can also be controlled by means of a passage passing through the partition - for example by means of a flap closing or releasing the passage - whereby the possibility is created to dampen a further engine order in addition to the dominant engine order.

It is also provided according to a development of the invention that the resonator has a housing body formed from a plastic material, whereby a reduction in the intrinsic mass of the resonator can be achieved. Finally, according to a further development of the invention, it is also provided that the exhaust system has a further neck opening extending from the respective exhaust pipe to the resonator volume and at least one of the existing neck openings is provided with a flap for at least partially releasing and / or closing the respective neck opening , This creates a configuration with which, in addition to a frequency to be damped, a second frequency can be damped. In the case of a closed flap, the resonator attenuates a first frequency by means of the still existing and permanently open neck opening and, when the flap is open, the resonator also dampens the sound second frequency. The two frequencies may be interfering frequencies in the sense of buzzing or droning or even to such a disturbing frequency and the other frequency then by a frequency that is to be reduced to admission or the like in terms of level.

The neck opening continuously opened in the direction of the resonator volume per exhaust line generates a bypass line with which the first interfering frequency is permanently damped, while the second disturbing frequency can be selectively damped or not dampened by releasing or closing the further neck opening.

Finally, according to the invention, a method for operating an exhaust system of an internal combustion engine of a vehicle is provided, as has been described above and the exhaust system is provided with an exhaust valve in an exhaust outlet, wherein provided by the method that the exhaust valve in overrun operation of the vehicle is closed. As a result, special disturbing frequencies in the overrun mode of the vehicle can be eliminated. The invention will be explained in more detail below with reference to the drawing. This shows in:

Figure 1 is a schematic representation of an embodiment of an exhaust system with two exhaust pipes and four Abgasauslassmündungen and a Helmholtz resonator.

FIG. 2 shows a representation similar to that of FIG. 1 with an additional rear silencer per exhaust gas line of the exhaust system; FIG. 3 shows a representation similar to that according to FIG. 1 with a switchable exhaust gas flap in an exhaust gas outlet orifice per exhaust gas line;

Fig. 4 is a view similar to that of FIG. 3 with an additional Rear silencer per exhaust system of the exhaust system;

FIG. 5 shows a representation similar to that of FIG. 1 with one resonator flap per neck opening; FIG.

6 shows a representation similar to that according to FIG. 5 with an additional rear silencer per exhaust gas line of the exhaust system;

7 shows a representation similar to that according to FIG. 6 with an additional exhaust gas flap in an exhaust gas outlet opening per exhaust gas line of the exhaust gas system;

8 shows a representation similar to that according to FIG. 7 with an additional rear silencer per exhaust system of the exhaust system; 9 is an illustration of an arrangement similar to that of FIG. 8 with a further neck opening in the direction of the resonator volume starting from the respective exhaust gas line, in addition to the neck opening per exhaust line which can be switched with a resonator flap; 10 shows a representation of an arrangement similar to that according to FIG. 6, which differs in that only one exhaust gas outlet orifice is provided per exhaust-gas line side;

Fig. 1 1 is a representation of an arrangement similar to that of Figure 9, but without exhaust flap in the region of the exhaust outlet. and

FIG. 12 shows an illustration of an arrangement similar to that according to FIG. 5, again with only one exhaust gas outlet opening per exhaust gas line side. 1 of the drawing shows a schematic representation of an embodiment of a twin-flow exhaust system 1 with Helmholtz resonator second

The twin-flow exhaust system 1 has two exhaust pipes 3 with a in the area between the two exhaust pipes 3, which emanate from a not shown internal combustion engine of a vehicle, also not shown, arranged resonator 4, which forms a resonator 5 of the Heimholtz resonator 2.

The resonator housing 4 has two extending in the direction of the exhaust pipes 3 branch lines 6, which form neck openings 7 of the Heimholtz resonator 2. The exhaust gas does not flow through the resonator housing 4, so that it is not acted upon by the hot exhaust gas with a heat flow passing through the resonator 2 during operation of the exhaust system 1 and can therefore be manufactured from a plastic material. The tuning of the Heimholtz resonator 2 via a respective combustion engine adapted interpretation of the resonator volume, the length of the Resonatorhalses, ie the length of the branch line 6, and the diameter of the Resonatorhalses. As a result of this tuning, the resonator 2 is designed for the frequency which has the highest sound pressure level in terms of magnitude of an orifice level measured, for example, during a test drive or registration run of the vehicle.

This can be done, for example, by carrying out a test drive with the vehicle without a Helmholtz resonator and the orifice level measured in a test track! is examined for the frequency that produces the highest sound pressure level during the test run. By appropriate tuning of the Heimholtz resonator to this frequency, this frequency can then be correspondingly reduced in a test drive with a Helmholtz resonator without the need for sound attenuation devices that operate according to the reflection method, absorption method or resonance method.

In the embodiment illustrated in FIG. 1, the exhaust system 1 has two exhaust gas outlet nozzles per exhaust gas line 3 or exhaust gas side. - -

fertilize 8, wherein the exhaust system 1 according to the invention is not limited to this number of Abgasauslassmündungen, but for example, each exhaust pipe 3 may have only one exhaust outlet 8, as for example in the embodiments of the exhaust system according to Fig. 10 to Fig. 12 of the drawing the case is.

Fig. 2 of the drawing shows a modified embodiment of the exhaust system 1 with a rear silencer 9 per exhaust gas side. With the rear silencer

9 can be influenced by the user of the vehicle acoustically perceptible sound image, for example in the direction of a sporty or low-frequency enriched sound image.

3 of the drawing shows an embodiment of an exhaust system 1, in which two exhaust gas outlet openings 8 are each provided with a reversibly closable exhaust gas flap 10. The exhaust flap 10 can be controlled via a device, not shown, for opening and closing the exhaust outlet 8. The device may for example be implemented by the engine control of the internal combustion engine, not shown, which outputs to an actuator of the exhaust valve 10, a control signal for closing the exhaust valve 10 when the vehicle and thus the internal combustion engine goes into a thrust state. Through the then closed exhaust flap

10, the emission of frequencies perceivable as booming is prevented.

Fig. 4 shows a further modified embodiment of the exhaust system 1 with two exhaust valves 10, one of which is provided at a Abgasauslaßmündung 8 and one provided per exhaust gas side rear muffler 9. With the rear muffler 9, the sound of the engine can be influenced, as it has already been mentioned above. FIG. 5 of the drawing shows an embodiment of the exhaust system 1 with two exhaust gas lines 3 and a Helmholtz resonator 2 connected between the exhaust lines 3, as has already been explained with reference to FIG. 1 of the drawing. In contrast to the embodiment according to FIG. 1, the Helmholtz resonator 2 according to FIG. 5 of the drawing can be switched, that is to say switched with respect to its damping function into a damping and a non-damping state. For this purpose, the neck openings 7 are changeable with a flap or resonator flap 1 arranged in the region of a respective neck opening 7 such that the neck openings 7 can be blocked or closed or opened. When the resonator flaps 1 1 are blocked by means of an actuation of the resonator flaps 1, the damping effect of the resonator 2 is canceled and, by means of an actuation of the resonator flaps 11 open or continuous neck openings 7, the resonator 2 performs the attenuation function described above. In all embodiments of the exhaust system 1 with Resonatorklappen 1 1, it is also provided according to the present invention that the Resonatorklappen 1 1 not only digitally can be opened or closed, but can also occupy angular positions between the open state and the closed state, whereby the degree of damping of the Resonator 2 can be variably adjusted. By changing the opening degree of the Resonatorklappen 11 does not change the resonance frequency of the damping but only the degree of damping according to the set opening angle of Resonatorklappen 1 1. Fig. 6 of the drawing shows an embodiment of an exhaust system 1 with controllable or controllable Resonatorklappen 1 1, as just have been described and a rear silencer 9 per exhaust gas side, with which the sound of the exhaust system can be designed. 7 of the drawing shows an embodiment of an exhaust system 1 with controllable or controllable resonator flaps 11 and additional exhaust flaps 10 in the region of two exhaust gas outlet openings 8. As has already been explained above, in addition to influencing the sound pattern of the combustion engine. By switching on or off the resonator 2 and the damping, for example, during the coasting of the vehicle are changed by the exhaust valves 10 are controlled by, for example, the engine control to close the corresponding exhaust outlet 8.

A further reduction in the sound level emitted by the exhaust system 1 can be achieved by significantly reducing the exhaust gas passage diameter of the exhaust gas outlet opening 8 without the exhaust valve 10 relative to the diameter of the exhaust pipe 3, so that the sound pattern of the internal combustion engine can be varied within a wide adjustment range ,

Fig. 8 of the drawing shows an embodiment of an exhaust system 1 similar to that shown in FIG. 7 with additionally provided per exhaust gas side, downstream of the resonator 2 arranged rear silencer 9 for influencing the sound of the engine.

FIG. 9 of the drawing shows a further modified embodiment of an exhaust system 1, in which two neck openings 12 are provided in addition to two first neck openings 7 which can be controlled or regulated by means of two resonator flaps 11, namely one neck opening 12 per exhaust pipe 3 a arranged between the respective exhaust pipe 3 and the resonator 4 branch pipe 13 is formed. This embodiment provides a switchable or controllable resonator 2 which also performs the function of a basic resonator. The term "base resonator" is understood to mean a resonator tuned to a first frequency-the base frequency-for the damping of which it is designed. The base frequency is determined inter alia by the opening diameter of the Halsöff- 12, so that the resonator shown in Fig. 9 of the drawing always attenuates the base frequency, since the branch lines 13 are constantly open. By way of example, the base frequency may be a frequency which dominates a sound level to be maintained during a test drive or certification run and which is therefore permanently damped. When the exhaust flaps 1 1 are opened, the resonator can also damp a second disturbing frequency. The branch lines 13 and the Resonatorklappen 1 1 can be matched in terms of their length and the common cross section to a required damping frequency, which may for example also be required for the registration drive damping frequency or a second, perceived as disturbing in a particular driving mode frequency ,

FIGS. 10 to 12 of the drawing show embodiments of exhaust systems with two exhaust pipes 3 and a respective resonator 2, each having only one orifice pipe or exhaust outlet orifice 8. The resonator 2 shown in FIG. 10 of the drawing has two controllable or controllable resonator flaps 11 whose function corresponds to the resonator flaps 1 1 explained in connection with FIG. 5 of the drawing.

Fig. 1 1 of the drawing shows an embodiment of an exhaust system 1 similar to that of FIG. 9 with additional neck openings 12, which are always open and resonator flaps 1 1. While the exhaust system shown in Fig. 9 of the drawing also two exhaust flaps 10 at two exhaust gas outlet 8, which are provided, for example, for damping drone frequencies in overrun operation of the vehicle, the exhaust system illustrated in FIG. 1 of the drawing, although the exhaust system according to FIG. 9 of the drawing, has two rear silencers 9, but not the exhaust valves 10.

The exhaust system shown in FIG. 1 1 of the drawing is provided, for example, to be arranged on an internal combustion engine, which does not generate disturbing drone frequencies in overrun mode, so that the exhaust flaps 11 can be omitted for cost reduction.

Finally, Fig. 12 of the drawing shows an exhaust system with two exhaust pipes 3 and via the Resonatorklappen 1 1 controllable or controllable resonator 2, so that also in this embodiment, the degree of damping of the resonator 2 according to the opening angle of the Resonatorklappen 1 can be changed. To reduce costs compared to the exhaust system shown in Fig. 10 of the drawing, the exhaust system shown in Fig. 12 of the drawing but has no rear silencer 9 per exhaust line side, as shown in the embodiment of FIG. 10 of the drawing.

Although in the embodiments of the exhaust system shown in the figures next to the respective Helmholtz resonator no further muffler housing are shown, may be arranged in the respective exhaust system, for example, a further sound damping device in the form of a center muffler in the area in front of the Helmholtz resonator.

In the respective embodiment with exhaust valves in the exhaust outlet port, the exhaust flap takes over the damping of disturbing frequencies, especially in overrun mode of the engine, in an embodiment with additional resonator flaps, the sound level at the exhaust gas outlet can be changed in many areas, and thus the acoustics of the exhaust system can be particularly affected in that a resonator which is at least partially opened by the opening of the resonator flaps assumes the function of a cross-talk station, so that a distinctly different sound pattern is produced, in particular in an internal combustion engine in V-arrangement, than in an exhaust system without a cross-talk station.

A resonator provided with additional neck openings which are always open can also be used for damping a disturbing frequency arising when the resonator flaps are closed. Since the resonator is not flowed through by hot exhaust gas, it can for example be made of a plastic material, resulting in a significant reduction in the dead weight of the resonator. By using plastic or, for example, a carbon-fiber reinforced plastic Stoffs the resonator can be adapted to the geometry of the underbody of the vehicle and thereby also shifted from the rear of the vehicle towards the center of the vehicle, which improves the crash behavior of the vehicle.

With regard to the above in detail not explained in detail features of the invention, reference is expressly made to the claims and the drawings.

LIST OF REFERENCE NUMBERS

1st exhaust system

2. Helmholtz resonator

3. Exhaust pipes

4. resonator housing

5. resonator volume

6. Branch lines

7. Neck opening

8. exhaust outlet port

9. Rear silencer

10. exhaust flap

1 1. flap, resonator flap

12. neck opening

13. branch line

Claims

Claims 1. Exhaust system for a vehicle having an internal combustion engine, with a Helmholtz resonator (2) and two exhaust gas lines (3) extending in the direction of the resonator, characterized in that the resonator (2) has two neck openings (7) to form a resonator volume (4) ) and in each case a neck opening (7) is coupled to an exhaust pipe (3) and the resonator (2) is tuned to dampen a dominant engine order.

2. Exhaust system according to claim 1, characterized in that the resonator (2) has a resonator volume (5) exhibiting housing (4) which is formed separately from other component housings of the exhaust system (1) and the housing (4) at a distance from Rear area of the vehicle is arranged.

3. Exhaust system according to claim 1 or 2, characterized by a respective in the region between the exhaust pipe (3) and the resonator (5) arranged flap (1 1) formed for at least partially releasing and / or closing the respective neck opening (7) is.

4. Exhaust system according to one of the preceding claims, characterized in that each exhaust pipe (3) in the flow direction of the exhaust pipes (3) downstream of the resonator (2) at least two Abgasauslaßmündungen (8) and at least one respective exhaust outlet port (8) with an exhaust flap ( 10) is provided, by means of which the exhaust outlet port (8) is reversibly closed.

5. Exhaust system according to claim 4, characterized in that the common cross section of the exhaust gas outlet openings (8) per exhaust pipe (3) is larger than the cross section of the exhaust pipe (3).

6. Exhaust system according to one of claims 3 to 5, characterized by a Device for the common control of the valve between the resonator (5) and the respective exhaust pipe (3) arranged flap (1 1).

7. Exhaust system according to one of claims 4 to 6, characterized by a device for the common control of in a respective outlet port (8) arranged exhaust flap (10).

8. Exhaust system according to one of the preceding claims, characterized by a device in the flow direction of the exhaust pipes (3) downstream of the resonator (2) provided for sound damping (9).

9. Exhaust system according to one of the preceding claims, characterized in that the resonator volume (5) is divided by means of a partition in at least two sub-volumes.

10. Exhaust system according to claim 9, characterized in that the partition wall has a passage connecting the sub-volumes.

1 1. Exhaust system according to one of the preceding claims, characterized in that the resonator (2) has a housing body formed from a plastic material (4).

12. Exhaust system according to one of the preceding claims, characterized by a respective further, from the respective exhaust pipe (3) to the Resonatorvo! (5) extending neck opening (12), wherein at least one of the neck openings (7) per exhaust pipe (3 ) is provided with a flap (11) for at least partially releasing and / or closing the respective neck opening (7).

13. A method for operating an exhaust system (1) of an internal combustion engine of a vehicle according to one of the preceding claims and the exhaust system

(1) is provided with an exhaust flap (10) in a Abgasauslassmündung (8), characterized in that the exhaust flap (10) is closed in the overrun operation of the vehicle.