EP2997240B1 - Exhaust system for an internal combustion engine and method for operating the exhaust system - Google Patents

Description

The invention relates to an exhaust system for an internal combustion engine with the features of the preamble of claim 1 and method for operating the exhaust system according to the features of the claims 6 to 8. From the German patent application DE 10 2009 032 213 A1 , starting from the present invention, an exhaust system for an internal combustion engine is known, having a first and a second cylinder, wherein the first cylinder, a first exhaust pipe and the second cylinder is associated with a second exhaust pipe and wherein the first exhaust pipe, a first silencer and the second exhaust pipe is associated with a second muffler, wherein from the first exhaust pipe upstream of a first obturator branches off a first damping tube first opens into a first chamber and then passed through the first muffler and opens into the second exhaust pipe downstream of a second obturator and that of the second exhaust pipe upstream of a second obturator branches off a second damping pipe, which first opens into a second chamber and then passed through the second silencer and opens into the first exhaust pipe downstream of the first obturator.

A disadvantage of this known prior art is the fact that the damping resonator of the muffler is not variably adjustable in terms of sound.

Further mufflers for exhaust systems are generally known from the prior art, which operate on the absorption and / or reflection principle. The development of such a muffler usually means finding the best possible compromise between muzzle noise (volume after exhaust tailpipe), exhaust back pressure and required muffler volume. To circumvent such a compromise solution are often silencer with one or more movable closure elements or shut-off devices, such as an exhaust flap, executed to allow different flow paths in the exhaust pipe of the silencer system. In silencer systems for internal combustion engines, two, three or even four exhaust system tailpipes are often provided. In the silencer embodiments known from the prior art, the arrangement of the closure elements leads disadvantageously to the fact that, depending on the position of the closure element, exhaust gas tailpipes or tailpipe branching elements are no longer flowed through with exhaust gas.

• → Irritation beim Kunden, da nicht aus allen Abgasanlagen-Endrohren Abgas austritt (sichtbar bei niedriger Außentemperatur durch Wasserdampf und am unterschiedlichen Verschmutzungsgrad der sichtbaren Endrohre);
• → Hoher Abgasgegendruck durch einen Engpass im Abgasanlagen-Endrohr;
• → Hörbares Strömungsrauschen durch den Engpass im Abgasanlagen-Endrohr;
• → Wärmespannung zwischen kaltem und heißem Abgasanlagen-Endrohr birgt die Gefahr der Rißbildung;
• → Aufwendige Führung der Dämpfungsrohre bei der Schalldämpferanlage;
• → Hohes Gewicht der Schalldämpferanlage;
• → Hohe Herstellkosten der Schalldämpferanlage;
• → Klappen sind üblicherweise nur bedingt getrennt bzw. zeitlich versetzt zu schalten, dies führt zu einem deutlichen Abgasgegendruckanstieg in einem Abgasstrang.

However, this prior art has the following disadvantages:

• → irritation at the customer, since exhaust gas does not escape from all exhaust system tailpipes (visible at low outside temperature due to water vapor and at the different degree of contamination of the visible tailpipes);
• → High exhaust back pressure due to a bottleneck in the exhaust system tailpipe;
• → Audible flow noise through the bottleneck in the exhaust system tailpipe;
• → thermal stress between cold and hot exhaust tailpipe runs the risk of cracking;
• → Elaborate guidance of the damping tubes at the silencer system;
• → high weight of the silencer system;
• → high production costs of the silencer system;
• → Flaps are usually only partially separated or shifted in time, this leads to a significant increase in exhaust gas back pressure in an exhaust system.

Object of the present invention is to avoid the disadvantages mentioned above and at the same time introduce a variability in the acoustic damping properties of the silencer system.

This object is achieved by the device in the characterizing part of patent claim 1 and procedurally by the features of claims 6 to 8.

The inventive design of the exhaust system, all the above problems are avoided. The exhaust system has a structure advantageous with respect to the exhaust backpressure. Due to the construction according to the invention, one or both shut-off valves can also be closed at the same time without a substantial increase in the exhaust backpressure. Compared with conventional exhaust systems exists with open shut-off devices, such. As exhaust valves, a minimum or hardly measurable throttling (increase in the exhaust backpressure), since the entire Abgasrohr- and damping tube volume is used to the end of the exhaust system. By a slightly different structure, the shut-off valves can also be shifted in time to improve a subjective hearing impression during the switching phases. The staggered switching of the two shut-off devices can be reduced to conspicuous, acoustic level jumps in an advantageous manner.

With regard to power and dynamics (response of the internal combustion engine), the very low exhaust back pressure of the exhaust system due to the inventive design has a very positive effect. For slight acoustic adjustments, the volumes of the first silencer and the second silencer can also be subsequently changed. In addition, one or more possibly necessary resonators can be easily integrated in the exhaust system while maintaining the symmetry in a simple manner. Due to the symmetrical design of the exhaust system, these and beyond the muffler itself can be very cheap.

• Das Schalldämpfergehäuse kann beispielsweise als kostengünstiger Wickeldämpfer oder in Schalenbauweise umgesetzt werden. Bei einer Umsetzung als Wickeldämpfer können die beiden Seitenteile als Gleichteile ausgeführt werden. In Schalenbauweise können die Ober- und die Unterschale jeweils aus Gleichteilen ausgeführt werden.

Many components of the exhaust system according to the invention can be manufactured or used as inexpensive common parts:

• The silencer housing can be implemented, for example, as a cost-effective coil damper or shell construction. When implemented as a winding damper, the two side parts can be designed as a common part. In shell construction, the upper and lower shell can each be made of identical parts.

The exhaust pipes can also be manufactured and installed as the same components.

The Y-branch elements of the exhaust pipes to the damping tubes can be implemented for example as hydroforming (IHU). The damping tubes with perforation, which are guided through the silencer, are also implemented as equal parts. The same applies to the damping pipe from the Y pipe section to the reflection chamber.

Also for the production can be saved because of the common parts for the exhaust system assembly tools. Depending on how the manufacturing of a manufacturer or supplier is constructed, for the pre-assembly of the Y-branching elements and the shut-off devices are used for both sides of the exhaust system the identical mounting device.

All of the above points lead to a significant reduction of the tool and manufacturing costs for the exhaust system according to the invention.

Due to the large proportion of identical parts and the reduction of individual part variants, it is also possible to realize a possibly desired lightweight construction much more easily.

Preferred developments of the exhaust system according to the invention for an internal combustion engine are described in the subclaims.

With the embodiment according to claim 2, several variants can be displayed in a simple manner.

The embodiment according to claims 3 to 5 again reduces the production costs.

With the method for operating an exhaust system for an internal combustion engine according to claim 6, a minimum sound attenuation is achieved.

With the method for operating an exhaust system for an internal combustion engine according to claim 7, an average sound attenuation is achieved.

With the method for operating an exhaust system for an internal combustion engine according to claim 8, a maximum sound attenuation is achieved.

Fig. 1

zeigt schematisch eine erfindungsgemäße Abgasanlage.

Fig. 2

zeigt die erfindungsgemäße Abgasanlage mit zwei geschlossenen Absperrorganen.

Fig. 3

zeigt die erfindungsgemäße Abgasanlage mit zwei geöffneten Absperrorganen.

Fig. 4

zeigt die erfindungsgemäße Abgasanlage mit einem geschlossenen und einem geöffneten Absperrorgan.

In the following, an exhaust system according to the invention and three methods for operating the exhaust system according to the invention are explained in more detail in four figures.

Fig. 1

schematically shows an exhaust system according to the invention.

Fig. 2

shows the exhaust system according to the invention with two closed shut-off valves.

Fig. 3

shows the exhaust system according to the invention with two open shut-off valves.

Fig. 4

shows the exhaust system according to the invention with a closed and an open shut-off.

Fig. 1 shows an end portion of an exhaust system 1 according to the invention for an internal combustion engine, not shown, with at least a first and a second, also not shown cylinder. The first and the second cylinder are representative of cylinder groups of the internal combustion engine. For example, in a six-cylinder internal combustion engine, the cylinders 1 to 3 of the cylinder group 1 and the cylinders 4 to 6 correspond to the cylinder group 2. The first cylinder is a first exhaust pipe 2 and the second cylinder is associated with a second exhaust pipe 3. Further, the first exhaust pipe 2, a first muffler 4 and the second exhaust pipe 3, a second muffler 5 is assigned.

According to the invention, a first damping pipe 2 'branches off from the first exhaust pipe 2 upstream of a first shut-off element 6. This first flows into a first reflection chamber 7 and is then passed through the first muffler 4 and opens again into the second exhaust pipe 3 downstream of a second obturator 8. In addition, branches from the second exhaust pipe 3 upstream of a second obturator 8, a second Damping tube 3 'from which first opens into a second reflection chamber 9 and then passed through the second muffler 5 and opens into the first exhaust pipe 2 downstream of the first obturator 6. Flow directions of the exhaust gases, which are represented by arrows are the Fig. 2 to 4 removable.

As is known from the prior art, the first damping tube 2 'and the second damping tube 3' in the volume of the first muffler 4 and in the region of the second muffler 5 on a perforation, for emitting sound emissions in the muffler 4, 5 for frequency-selective Attenuation of the sound pressure level. The damping effect is in the Fig. 2 to 4 symbolically represented by dashed lines in the area of the perforation.

In the present embodiment, the first and the second obturator 6, 8 is an exhaust valve, in other embodiments, it may for example be rollers.

Next to the first exhaust pipe 2 downstream of the first obturator 6, a third reflection chamber 10 and the second exhaust pipe 3 downstream of the second obturator 8, a fourth reflection chamber 11 assigned. In another embodiment, a reflection chamber 10, 11 omitted.

Preferably, the first exhaust pipe 2 is connected via a perforation 12 exhaust gas leading to the third reflection chamber 10 and / or the second exhaust pipe 3 via a perforation 12 exhaust gas leading to the fourth reflection chamber 11. In a further embodiment, the first and the third reflection chamber 7, 10 and / or the second and the fourth reflection chamber 9, 11 may be connected to each other exhaust-conducting, for example by a further perforation. By this measure, a further acoustic optimization is possible.

Particularly preferably, the first and the second muffler 4, 5 are arranged in a common housing 13, whereby manufacturing costs are saved.

In yet another particularly preferred embodiment, the first and the second reflection chamber 7, 9 are arranged in the housing 13. The greatest cost saving is achieved if even the third and the fourth reflection chamber 10, 11 are arranged in the housing 13.

In yet another embodiment, the first and second reflection chambers 7, 9 can also be designed as resonator chambers.

Again, in another embodiment, the third and the fourth reflection chamber 10, 11 may be designed as absorption chambers. The particular embodiment of a reflection chamber, a resonator chamber, or absorption chamber will not be described in detail, since this is sufficiently defined in standard textbooks.

Due to the symmetrical design of the entire exhaust system 1, in particular the manufacturing costs can be reduced, since the common parts principle can be applied in wide proportions. For example, the Y-branch pipes (transition region from the exhaust pipe to the damping pipe), the damping pipes 2 ', 3', the shut-off elements 6, 8, the tail pipe branches, the reflection chambers 7, 9, 10, 11, the mufflers 4, 5 and the exhaust pipes 2, 3 are designed as equal parts. In a particularly advantageous manner, the muffler 4, 5, the reflection chambers 7, 9, 10, 11 accommodate cost in a single common housing 13.

Also for the production can be 1 assembly tools save due to the common parts for the exhaust system. This also leads to a significant reduction in tooling costs.

In the Fig. 2 to 4 in which the same reference numbers apply to identical components as in Fig. 1 , the same exhaust system 1 as in Fig. 1 shown again, but for three different operating conditions. Exhaust gas flow directions are, as already explained above, each schematically represented by arrows.

Fig. 2 shows the exhaust system 1 according to the invention with a setting for a first operating method, wherein the first and the second obturator 6, 8 are closed. By this setting, a maximum sound attenuation for the exhaust system 1 is achieved.

Fig. 3 shows the exhaust system 1 according to the invention with a setting for a second operating method, wherein the first and the second obturator 6, 8 are open. By this setting a minimum sound attenuation for the exhaust system 1 is achieved.

Fig. 4 shows the exhaust system 1 according to the invention with a setting for a third operating method, wherein the first obturator 6 is closed and the second obturator 8 is opened. By this setting, an average sound attenuation for the exhaust system 1 is achieved.

The exhaust system 1 according to the invention has a construction which is very advantageous with regard to the exhaust backpressure. As a result of the design according to the invention, one or both shut-off elements 6, 8 can also be closed at the same time without a substantial increase in the exhaust backpressure. Compared with conventional exhaust systems with open shut-off valves 6, 8, such. As exhaust valves, a minimum or hardly measurable throttling (increase in the exhaust backpressure), since the entire exhaust - from the damping tube volume until the end of the exhaust system 1 - is used. By a slightly different construction, the shut-off devices 6, 8 can also be switched over in time to improve a subjective hearing impression during the switching phase. By staggered switching of the two shut-off valves 6, 8 can be reduced to conspicuous acoustic level jumps in an advantageous manner.

With regard to power and dynamics (response of the internal combustion engine), the very low exhaust backpressure of the exhaust system 1 due to the embodiment according to the invention has a very positive effect. For slight acoustic adjustments, the volumes of the first muffler 4 and the second muffler 5 can also be subsequently changed. In addition, one or more possibly necessary resonator chambers 10, 11, which are also designed as reflection chambers, can be integrated in the exhaust system 1 in a simple manner without great expense, while maintaining the symmetry.

Due to the arrangement of the first and the second adjusting element 6, 8 in the first and in the second exhaust pipe 2, 3 in the flow direction of the exhaust gas in front of the exhaust pipe, a switching operation of outsiders is practically not heard.

LIST OF REFERENCE NUMBERS

1.

exhaust system

Second

first exhaust pipe

2 '

first damping tube

Third

second exhaust pipe

3 '

second damping tube

4th

first silencer

5th

second silencer

6th

first obturator

7th

first reflection chamber (resonator chamber)

8th.

second obturator

9th

second reflection chamber (resonator chamber)

10th

third reflection chamber (absorption chamber)

11th

fourth reflection chamber (absorption chamber)

12th

perforation

13th

casing

Claims (8)

1. An exhaust system (1) for an internal combustion engine, comprising at least a first and a second cylinder, wherein associated with the first cylinder is a first exhaust pipe (2) and associated with the second cylinder is a second exhaust pipe (3) and wherein associated with the first exhaust pipe (2) is a first silencer (4) and associated with the second exhaust pipe (3) is a second silencer (5), wherein branching off from the first exhaust pipe (2) upstream of a first shut-off element (6) is a first damping pipe (2') which initially leads into a first chamber and is then guided through the first silencer (4) and leads into the second exhaust pipe (3) downstream of a second shut-off element (8), and branching off from the second exhaust pipe (3) upstream of a second shut-off element (8) is a second damping pipe (3') which initially leads into a second chamber and is then guided through the second silencer (5) and leads into the first exhaust pipe (2) downstream of the first shut-off element (6), and wherein associated with the first exhaust pipe (2) downstream of the first shut-off element (6) is a third reflection chamber (10) and/or associated with the second exhaust pipe (3) downstream of the second shut-off element (8) is a fourth reflection chamber (11),
   characterised in that the first and second chambers are reflection chambers (7, 9), the first and the third reflection chambers (7, 10) and/or the second and the fourth reflection chambers (9, 11) being interconnected in an exhaust-gas conveying manner.
2. An exhaust system according to claim 1,
   characterised in that the first exhaust pipe (2) is connected to the third reflection chamber (10) by perforations (12) in an exhaust-gas conveying manner, and/or the second exhaust pipe (3) is connected to the fourth reflection chamber (11) by perforations (12) in an exhaust-gas conveying manner.
3. An exhaust system according to either of claims 1 or 2,
   characterised in that the first and the second silencers (4, 5) are arranged in a common housing (13).
4. An exhaust system according to claim 3,
   characterised in that the first and the second reflection chambers (7, 9) are arranged in the housing (13).
5. An exhaust system according to either of claims 3 or 4,
   characterised in that the third and the fourth reflection chambers (10, 11) are arranged in the housing (13).
6. A method for operating an exhaust system according to any of claims 1 to 5,
   characterised by the following method step:

   - opening the first and the second shut-off elements (6, 8) for minimum silencing.
7. A method for operating an exhaust system according to any of claims 1 to 5,
   characterised by the following method step:

   - opening the first shut-off element (6) and closing the second shut-off element (8) for medium silencing.
8. A method for operating an exhaust system according to any of claims 1 to 5,
   characterised by the following method step:

   - closing the first and the second shut-off elements (6, 8) for maximum silencing.

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