EP1321639B2 - Silencer arrangement - Google Patents

Abstract

An automotive exhaust pipe silencer has a housing (1) with two exhaust gas inlets and two exhaust gas outlet pipes. A first exhaust gas pipe (17) links an inlet (6) with an outlet (8), passing directly through the silencing chamber and is essentially straight. The pipe (17) centre section has outlets (20) to the housing (1) chamber. The exhaust pipe (17) extension beyond the outlet (8) esp. has a throttle valve (22a).

Description

The present invention relates to a sound damping device according to the preamble of claim 1.

It is known that mufflers produce a back pressure that lowers the performance of the internal combustion engine. A further reduction results from the use of catalytic converters, which are flowed through by the exhaust gases. Due to the increasing demands on the cleaning effect of the catalytic converters, these are increasingly hochzelliger and thereby generate an ever greater back pressure.

A sound damping device of the type mentioned is from the US-A-5014817 known. Further sound damping devices are in the GB-A-2223535 and the DE 41 40 429 A disclosed.

It is an object of the invention to provide a sound damping device of the type mentioned by which the performance of the engine is affected as little as possible. At the same time, however, a sufficient sound attenuation should be maintained.

This object is solved by the features of claim 1. By using a substantially straight exhaust pipe, the exhaust back pressure in the first exhaust pipe is greatly reduced. At the same time, the first exhaust pipe can be at least partially blocked in driving states with high exhaust gas noise development through the shut-off device, so that the exhaust gas flow must at least largely escape through the second exhaust gas outlet opening of the sound damping device. This can be achieved in these driving conditions, a high sound damping effect. Especially at low speeds, where a high silencing effect is required, the shut-off device can be adjusted to its shut-off position, while in the high speed range in which a large exhaust gas flow, the flow releases, so that the lowest possible back pressure is built up. The sound damping device according to the invention therefore combines a relatively low power reduction of the internal combustion engine with a relatively high sound attenuation.

According to the invention, the first exhaust pipe between the associated exhaust gas inlet opening and the associated exhaust gas outlet opening is formed as a continuous pipe, wherein the first exhaust pipe in its wall in the flow direction upstream of the shut-off device in particular has at least one perforated region. The continuous design of the first exhaust pipe leads with open shut-off device to a largely trouble-free exhaust gas flow in the first exhaust pipe, while the perforation in the wall of the first exhaust pipe with closed shut-off device allows the exhaust gas from the first exhaust pipe via the interior of the muffler housing through the second exhaust gas outlet opening.

The shut-off device of the sound damping device according to the invention is adjustable in dependence on the engine speed that the shut-off device locks the first exhaust pipe at low speeds and releases at high speeds to cause on the one hand at low speeds high sound attenuation and on the other hand at high speeds the lowest possible back pressure.

The shut-off device of the sound damping device according to the invention is preferably designed as a controllable exhaust flap, which can be actuated, for example via a connectable to the air intake pipe of the internal combustion engine vacuum box. Butterfly valves with vacuum cans are in use and can therefore be used favorably for the purpose of the invention. They are also functionally reliable, relatively inexpensive to manufacture and have a sufficient longevity. About the vacuum box, a speed-dependent adjustment of the exhaust valve can be achieved in a simple manner, since the negative pressure in the air intake of the engine also increases with increasing speed.

According to the invention a second exhaust pipe is provided in the muffler housing, one end of which is connected to the second exhaust gas outlet opening, wherein the second exhaust pipe is in flow connection via at least one opening with the openings of the first exhaust pipe. This results in various design options of the sound damping device according to the invention.

In particular, according to an embodiment of the invention, the other end of the second exhaust pipe can be arranged freely in the interior of the muffler housing. This variant is preferably used in sound damping devices in which the muffler housing has only one exhaust gas inlet opening, but two exhaust gas outlet openings, such as in two-pipe exhaust systems with two rear silencers, which are each connected to one of the two exhaust pipes. The exhaust gas flowing through the one exhaust gas inlet opening then flows through the two exhaust gas outlet openings when the exhaust gas flap is open, whereas with the exhaust valve closed, it is forced to flow out of the first exhaust pipe into the second exhaust pipe via the interior of the silencer housing in order to reach it via the second exhaust gas outlet opening , In this second case, this results in a high sound damping performance, while in the first case, a particularly low exhaust back pressure is given.

According to another embodiment of the invention, the other end of the second exhaust pipe is connected to a second exhaust gas inlet opening. This variant can be used with two-pipe exhaust systems with only one rear silencer by the sound damping device connected with its two exhaust gas inlet openings to each an exhaust pipe of the two-pipe exhaust system becomes.

According to one embodiment of the invention, the second exhaust pipe may be formed continuously between the exhaust gas inlet opening and the exhaust gas outlet opening like the first exhaust pipe and may have at least one perforated area in its wall. In this embodiment, a particularly low exhaust back pressure results in the second exhaust pipe. With the first exhaust pipe closed, exhaust gas can flow out of the first exhaust pipe via the second exhaust pipe via the perforated wall.

According to a further embodiment of the invention, the second exhaust pipe is formed in two parts, with a first part, one end of which is connected to the second exhaust gas inlet opening and the other end opens freely inside the muffler housing, and a second part, whose one end to the second exhaust gas outlet opening is connected and the other end opens freely inside the silencer housing. By this two-part design of the second exhaust pipe, the sound damping effect of the sound damping device according to the invention can be influenced. For example, the free ends of the two parts of the second exhaust pipe may open into a resonance chamber. Over the length, in particular of the second part of the second exhaust pipe, the sound damping device can be tuned. That is, the frequency range in which the greatest silencing effect occurs can be selected over its length and cross section.

The muffler housing may additionally have at least one absorption chamber. The two exhaust pipes are then preferably passed through the absorption chamber and have within this at least one perforated region in its wall. Over the perforated area, a flow connection to the absorption chamber is provided, so that an additional sound attenuation is achieved.

According to the invention, the resonance chamber is arranged between two absorption chambers. According to a particularly preferred embodiment of the invention, the two exhaust pipes are passed through two absorption chambers. In the resonance chamber open the free ends of the two parts of the second exhaust pipe and is a perforated wall portion of the first exhaust pipe. As a result, with the shut-off device closed, exhaust gas can pass from the first exhaust pipe into the resonance chamber and from this via the second part of the second exhaust pipe through the second exhaust gas exit opening. The three chambers are also separated by a perforated wall. In this way, the two absorption chambers are in fluid communication with the resonance chamber and each other. It has been shown that a particularly good sound damping effect can be realized with relatively low back pressure by this structure.

Fig. 1

eine Seitenansicht einer erfindungsgemäßen Schalldämpfungseinrichtung,

Fig. 2

eine Draufsicht auf die Oberseite der Schalldämpfungseinrichtung von Fig. 1,

Fig. 3

eine Ansicht gemäß Fig. 2, jedoch mit abgenommenem oberen Gehäuseteil, einer ersten Variante der erfindungsgemäßen Schalldämpfungseinrichtung,

Fig. 4

eine Ansicht gemäß Fig. 3 einer zweiten Variante der erfindungsgemäßen Schalldämpfungseinrichtung,

Fig. 5

eine Ansicht gemäß Fig. 3 einer dritten Variante der erfindungsgemäßen Schalldämpfungseinrichtung, und

Fig. 6

eine Ansicht gemäß Fig. 3 einer vierten Variante der erfindungsgemäßen Schalldämpfungseinrichtung.

Embodiments of the invention are illustrated in the drawings and will be described below. They show, in each case in a schematic representation,

Fig. 1

a side view of a sound damping device according to the invention,

Fig. 2

a top view of the top of the sound damping device of Fig. 1 .

Fig. 3

a view according to Fig. 2 , but with removed upper housing part, a first variant of the sound damping device according to the invention,

Fig. 4

a view according to Fig. 3 a second variant of the sound damping device according to the invention,

Fig. 5

a view according to Fig. 3 a third variant of the sound damping device according to the invention, and

Fig. 6

a view according to Fig. 3 A fourth variant of the sound damping device according to the invention.

The illustrated sound damping device comprises a muffler housing 1, which has a lower shell 2 and an upper shell 3, as in Fig. 1 and 2 is recognizable. The lower shell 2 and the upper shell 3 are connected to one another in their edge region, in particular welded. On the exhaust gas outlet side of the muffler housing 1, two exhaust tailpipes 4, 5 are arranged.

In the presentation of Fig. 3 you recognize the inner structure of the in the Fig. 1 and 2 illustrated sound damping device. The interior of the muffler housing 1 is divided between the two exhaust gas inlet openings 6, 7 on the one hand and the two exhaust gas outlet openings 8 and 9 on the other hand by two spaced apart perforated walls 10 and 11 in an exhaust gas inlet side first chamber 12, a subsequent second chamber 13 and an exhaust gas outlet side third chamber 14 , The first chamber 12 and the third chamber 14 are each formed as an absorption chamber and, as indicated by the cross-hatching, filled with a sound absorption material. The intermediate second chamber 13, however, is designed as a reflection chamber. The two perforated walls 10 and 11 are also each on their side facing the absorbent material with a steel wool mat 15, 16 occupied.

The three chambers 12, 13, 14 are traversed by a continuous first exhaust pipe 17, which is arranged between the first exhaust gas inlet opening 6 and the first exhaust gas outlet opening 8. The first exhaust pipe 17 consists of two parts which are inserted into each other with sliding fit. As well as in Fig. 3 recognizes, the first exhaust pipe 17 is just executed except for a bent portion in the region of the first exhaust gas outlet opening 8.

Within the first chamber 12, the wall of the first exhaust pipe 17 has a perforated region 18. About this perforation 18, the interior of the first exhaust pipe 17 communicates with the interior of the first absorption chamber 12 in connection. In addition, the first exhaust pipe 17 is coated within the first chamber 12 with a chrome steel wool stocking 19. In the region of the second chamber 13, the wall of the first exhaust pipe 17 also has a perforated region 20, via which the interior of the first exhaust pipe 17 communicates with the interior of the second chamber 13 formed as a reflection chamber. Finally, the first exhaust pipe 17 is connected on the exhaust gas outlet side outside the muffler housing 1 via a connecting pipe 21 with the first exhaust pipe end 4, as can be seen in particular Fig. 2 recognizes. In the region of the connecting pipe 21, a vacuum unit 22 which can be connected to the air intake line of an internal combustion engine is arranged, via which an exhaust gas flap 22a arranged within the connecting pipe 21 can be actuated. That is, the exhaust flap 22a, which is only indicated here, can be adjusted between a position which essentially blocks the connecting tube 21 and a position which releases it.

The first chamber 12 of the muffler housing 1 is further traversed by a first part 23 'of a second exhaust pipe 23, whose one end is connected to the second exhaust gas inlet opening 7 and the other end with its opening 24' in the second chamber designed as a reflection chamber 13 free empties. Also, the first part 23 'of the second exhaust pipe 23 has within the first chamber 12 on a perforated portion 25 and is covered with a chrome steel wool stocking 19.

In the second chamber 13 opens with its opening 24 "also has an end of a second part 23" of the second exhaust pipe 23, whose other end is connected to the second exhaust gas outlet opening 9. In fact, here as in the first exhaust pipe 17, the exhaust gas outlet end is led out of the muffler housing 1, as in Fig. 3 is recognizable. How to get in Fig. 3 In addition, the second part 23 "of the second exhaust pipe 23 is curved in both the third chamber 14 and the second chamber 13 and extends with its free end above the first exhaust pipe 17. In this way, a desired length of the second part 23 "of the second exhaust pipe for frequency tuning housed in the muffler housing 1.

In the Fig. 4 illustrated second variant is largely consistent with the variant of Fig. 3 match. The only difference is that here the second part 23 'of the second exhaust pipe 23 is formed shorter than in the first variant. Accordingly, the second part 23 'of the second exhaust pipe 23 in the second chamber 13 extends straight and does not extend over the first exhaust pipe 17. The shorter design of the second part 23 "of the exhaust pipe, the sound damping device is tuned to a different frequency. the maximum sound attenuation takes place at a different frequency than in the first variant.

Also in Fig. 5 illustrated third variant is largely consistent with the first variant of Fig. 3 match. In contrast to the first and the second variant, however, here the second exhaust pipe 23 is not formed in two parts but continuously and extends substantially straight through all three chambers 12, 13 and 14. By this configuration, a relatively low back pressure in the second exhaust pipe 23 generated. For connecting the second exhaust pipe 23 to the resonance chamber 13, in this variant the second exhaust pipe 23, like the first exhaust pipe 17, has a perforated region 26 in the resonance chamber 13.

During operation of the sound damping device according to the invention, the exhaust valve 22a is adjusted by the vacuum box 22 in response to the negative pressure in the air intake pipe of the engine and thus in dependence on the engine speed. The adjustment takes place in such a way that the exhaust flap 22a essentially closes off the connecting pipe 21 between the first exhaust pipe 17 and the tail pipe 4 at low rotational speeds, but releases it at high rotational speeds. At low speeds, a high sound attenuation is achieved in this way, since the exhaust gas flowing through the first exhaust pipe 17 can not escape via the first exhaust gas outlet opening 8. Instead, the exhaust gas has to escape via the perforation 20, the resonance chamber 13 and the opening 24 "of the second part 23" or the perforation 26 of the second exhaust pipe 23 together with the exhaust gas flowing through the second exhaust gas inlet opening 7 through the second exhaust gas outlet opening 9. Since the exhaust gas flow at low speeds is still relatively low, nevertheless builds up not too large exhaust back pressure. At the same time, however, a good sound attenuation is achieved.

At high speeds at which the exhaust valve 22a is opened, the exhaust gas flowing through the first exhaust gas inlet opening 6 can flow out unhindered through the first exhaust gas outlet opening 8, while the exhaust gas flowing through the second exhaust gas inlet outlet flows through the second exhaust gas outlet opening 9 after passing through the resonance chamber 13. This and the straight passage of the exhaust gas flow through the first exhaust pipe 17 results in a particularly low exhaust back pressure, so that the performance of the internal combustion engine is only slightly affected. An even lower exhaust back pressure results in the in Fig. 5 shown third variant in which the exhaust gas flow through the second exhaust pipe 25 flows straight ahead.

At the in Fig. 6 has shown variant the muffler housing 1 only an exhaust gas inlet opening 6. Accordingly, the second exhaust pipe 23 is arranged with one end freely in the muffler housing 1. It opens there with its opening 24 in the interior of the resonance chamber 13. The other end of the second exhaust pipe 23 is connected to the second exhaust gas outlet opening 9, as in the other variants.

The remaining structure of this variant is the same in principle with the structure of the other variants. One difference is that the second exhaust pipe 23 is guided through all three chambers 12, 13, 14 and has a deflection in the region of the first chamber 12. In addition, the two exhaust gas outlet openings 8, 9 are connected via a fork 27 to a common end pipe 28.

The function is basically the same again. In operation, the exhaust flap 22a is adjusted by the vacuum box 22. At low speeds, the exhaust flap 22a closes the connected to the first exhaust gas outlet opening branch 27a of the fork piece 27 while it releases it at high speeds. At low speeds, the exhaust gas flowing through the exhaust gas inlet opening 6 can therefore only escape through the second exhaust pipe 23 and the second exhaust gas outlet opening 9 and the other branch 27b of the fork piece 27. The sound-damping effect is thereby high. At high speeds and open exhaust flap 22a, however, the exhaust gas can also escape through the first exhaust port 8. The exhaust back pressure is therefore particularly low.

LIST OF REFERENCE NUMBERS

1

muffler housing

2

subshell

3

Upper shell

4

tailpipe

5

tailpipe

6

first exhaust gas inlet opening

7

second exhaust gas inlet opening

8th

first exhaust gas outlet opening

9

second exhaust gas outlet opening

10

Pegboard

11

Pegboard

12

first chamber

13

second chamber

14

third chamber

15

Steel wool mat

16

Steel wool mat

17

first exhaust pipe

18

perforation

19

Chrome steel wool sock

20

perforation

21

connecting pipe

22

Vacuum unit

22a

exhaust flap

23

second exhaust pipe

23 '

first part of the second exhaust pipe

23 "

second part of the second exhaust pipe

24, 24 ', 24 "

Opening of 23, 23 'or 23 "

25

perforation

26

perforation

27

forked piece

27a, b

Branches of 27

28

tailpipe

I

Exhaust gas flow direction

Claims (10)

1. A silencer device for combustion engines having a silencer housing (1) with at least one exhaust gas inlet opening (6, 7) and with at least two exhaust gas outlet openings (8, 9), in particular a rear silencer of a two-pipe exhaust gas system, in which a substantially straight first exhaust pipe (17) is provided which connects an exhaust gas inlet opening (6) to a first exhaust gas outlet opening (8) and whose interior is in communication via at least one opening (20) with the interior of the silencer housing (1); in which a barrier device (22a) is arranged in the flow direction (I) after the openings (20) and is adjustable between a position at least partly suppressing the exhaust gas flow through the first exhaust gas outlet opening (8) and a position freeing it, wherein the barrier device (22a) is adjustable in dependence on the speed of the combustion engine such that the barrier device (22a) blocks the first exhaust pipe (17) at low speeds and frees it at high speeds; and in which a second exhaust pipe (23) is provided whose one end is connected to the second exhaust gas outlet opening (9), wherein the second exhaust pipe (23) is in flow communication via at least one opening (24, 24', 24", 26) with the openings (20) of the first exhaust pipe (17),
   characterized in that
   the first exhaust pipe (17) is configured as a throughgoing pipe between the exhaust gas inlet opening (6) and the exhaust gas outlet opening (8);
   in that the openings (20, 26) of the first exhaust pipe (17) and of the second exhaust pipe (23) or the free ends of the second exhaust pipe (23) are arranged in a common resonance chamber (13); and
   in that the resonance chamber (13) is arranged between two absorption chambers (12, 14).
2. A silencer device in accordance with claim 1,
   characterized in that
   the first exhaust pipe (17) has at least one perforated region (20) in its wall in the flow direction before the barrier device (22a).
3. A silencer device in accordance with one of the preceding claims, characterized in that
   the barrier device (22a) is configured as a regulable exhaust flap.
4. A silencer device in accordance with any one of the preceding claims, characterized in that
   the barrier device (22a) is actuable via a vacuum actuator (22) connectable to the air suction line of the combustion engine.
5. A silencer device in accordance with any one of the preceding claims, characterized in that
   the other end of the second exhaust pipe (23) is freely arranged in the interior of the silencer housing (1).
6. A silencer device in accordance with any one of the claims 1 to 4, characterized in that
   the other end of the second exhaust pipe (23) is connected to a second exhaust gas inlet opening (7), with the second exhaust pipe (23) preferably being made throughgoing between the exhaust gas inlet opening (7) and the exhaust gas outlet opening (9) and having at least one perforated region (26) in its wall, or with the second exhaust pipe (23) preferably being made in two parts, with a first part (23') whose one end is connected to the second exhaust gas inlet opening (7) and whose other end opens freely in the interior of the silencer housing (1) and with a second part (23") whose one end is connected to the second exhaust gas outlet opening (9) and whose other end opens freely in the interior of the silencer housing (1).
7. A silencer device in accordance with any one of the preceding claims, characterized in that
   the silencer housing additionally has at least one absorption chamber (12, 14).
8. A silencer device in accordance with any one of the preceding claims, characterized in that
   at least one exhaust pipe (17, 23) is conducted through at least one absorption chamber (12) and has at least one perforated region (20, 26) in its wall within said absorption chamber.
9. A silencer device in accordance with any one of the preceding claims, characterized in that
   at least one absorption chamber (12, 14) is in flow communication with the resonance chamber (13).
10. A silencer device in accordance with any one of the preceding claims, characterized in that
    two silencer housings (1) having an exhaust gas inlet opening (6) and two exhaust gas outlet openings (8, 9) are provided and are each connected to an exhaust pipe of a two-pipe exhaust gas system.

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