DE2206875A1 - SILENCER - Google Patents

Description

ORiGlNAl

The * e Xerox copy

is considered Originci 2206875

Applicant:. 67 Ludwigshafen, February 11, 1972

Motor Condensator Walker

Manufacturing Company GmbH & Co. KG P 4897 I / wüs

68 Mannheim 1

Friesenheimer Strasse 23 - $ 2

Representative:

Pat ent attorneys e

Dipl.-Ing. Adolf H. Fischer
Dipl.-Ing. Wolf -Diet he fisherman
67 Ludwigshafen am Rhein
Richard-Wagner-Strasse 22

silencer

The invention relates to silencers for connection to internal combustion engines, as they are installed in motor vehicles in a known manner. In vehicles of this type, in which the internal combustion engine is at the front, the exhaust gases are generally passed through exhaust lines running under the vehicles to the end of the vehicle de to outdoors. A direct flow occurs in the lines with superimposed, periodically occurring exhaust pulses . Fundamental frequency, frequency spectrum and intensity of the exhaust pulses depend on the operating conditions of the internal combustion engine (load, speed, etc.).

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Like in Pig. 1 of the accompanying drawing, one, two, and more rarely, more mufflers are arranged in the course of the exhaust pipe, by means of which the exhaust pipe is divided into two, three or more pieces of equal length or of different lengths, the mufflers serving to prevent the sound waves from propagating in to insulate the exhaust line, ie to smooth the exhaust impulses and convert them as far as possible into a direct flow.

In this context, however, one must not consider the silencer on its own, but one must consider that the silencer with the connected lines together form a vibration system in which the effect of the silencer itself through resonances in the lines and the interaction of the lines with the volumes in the silencers is superimposed. It is therefore the place where the silencer or silencers are installed in the line system, in many cases of decisive importance for the effectiveness of such a silencer. In practice, the types of installation of the silencers are primarily determined by the space available below the vehicle. If a favorable choice of the installation location is not possible, resonances can occur in the pipes at certain speeds . the silencers cannot be attenuated because their frequency is below the lower limit frequency of the built-in silencers. Such pipe resonances then usually lead to unpleasant humming noises, which are punished by the opening of the tailpipes into the open.

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It is known that pipe resonances are fundamentally reduced by the installation of additional silencers Small volumes at suitable points in the course of the line can be reduced or shifted to such an extent that the humming noises at the muzzle are largely eliminated. But if the additional work involved in this additional silencer is undesirable or if there is no space in the appropriate places, so can the tube resonances by means of matched Helmholtz resonators Reduce or completely eliminate within the existing silencers. This vote however, usually requires large volumes for the low exhaust gas pulse frequencies, which in the silencer are not available, which is why there are limits to the use of resonators in the silencer are.

Some examples of well-known designs are in the Pig. 2a, 2b and 2c shown, which will be discussed in detail will.

The invention has now set itself the task of also • 'when using relatively short resonator chambers and therefore to attenuate very low frequencies with a relatively small resonator volume and through the associated Expansion of the damping range of the resonator damping to a much broader field of application open.

The solution to this problem is to be found by the invention constructive measures to combine sufficiently long resonator tubes with the resonator chambers and to be accommodated in the silencer, whereby this resonator

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tubes are the only connection between resonator chambers and show the remaining silencer volume. This is done by the fact that the resonator tube in the area of his The inlet opening facing the rest of the silencer volume is mounted in the resonator chamber partition is and protrudes with most of its length into the resonator chamber, where it is used to accommodate the length has a bend and in the area behind the pipe bend parallel or at a small angle to the chamber partition and thus runs transversely to the longitudinal axis of the chamber

In a design according to the invention, a curved resonator tube (U- or V-shape) is used, which is in the area its inlet opening facing the rest of the silencer volume is stored in the resonator chamber partition and the largest part of which protrudes into the resonator chamber and is parallel or approximately behind the pipe bend parallel to the chamber partition, ie. runs transversely to the longitudinal axis of the chamber.

In a further design, the resonator tube is located with most of its length outside the / Resonator volume, protrudes telescopically into one of the gas-carrying perforated tubes and is in the area of its inlet opening fastened in this perforated tube in the area of its outlet opening in the resonator chamber partition.

With a combination of the two above-mentioned designs, the resonator tube can be extremely long if it extends telescopically into one of the gas-carrying perforated pipes on one side and is attached there, on the other Side runs transversely in the resonator chamber by means of a pipe bend.

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According to a further proposal of the invention can the resonator can also be designed so that the resonator tube is entirely in the resonator chamber is located, runs parallel to the partition wall, is attached to it and via coincident openings in the Pipe jacket and in the partition with the remaining volume in communication. The corresponding Openings are sealed against each other so that the resonator tubes are not acoustically short-circuited will. According to the invention, the seal can be made by a collar on the partition wall opening, the serves to accommodate the edge of the opening in the resonator tube. Furthermore, the end of the resonator tube, which is adjacent to the coupling opening, closed, so that the full length of the resonator tube is effective for the damping adjustment.

In all designs, the resonator tubes can have a round, oval or angular cross-section. In the case of the design with the resonator tube located entirely in the resonator tube and aa the partition wall, it is advantageous to flatten the round cross-section in order to do so

the pipe rests and attaches better to the partition wall can be.

All erfindu'i ^ agefliäße Bauformon described are based on the idea to combine kuri'.e Hesonatorkanuaeno ir.it long resonator tubes _t where according to the invention, most of the tube length transversely in the. Extends resonator chambers or in a gas-carrying pipe of the rest of the muffler part.

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Further features of the invention will si oh from the following description of embodiments in conjunction with the drawings and the claims.

It show in schematic sketches

Fig. 1 shows the general arrangement of

Silencers in the exhaust line

2a, b, c known designs of silencers with Helmholtz resonators

Fig. 3 shows a muffler according to the proposal of the invention with a curved resonator tube in the Kai -er

Fig. 4 shows the arrangement of a resonator tube

parallel to the partition

Fig. 5 shows a silencer according to the invention, in which a long

• ■

'' Resonator tube in the inlet tube

protrudes.

In FIGS. 2a, 2b and 2c, known silencer designs with Helmholtz resonators are shown, these resonators being arranged at the beginning and / or at the end of the silencer. The silencer consists of a tubular jacket 1, which can be oval or round and which is closed with a cover 8 or 13 at both ends . The inner floors are divided into several chambers, with the lids

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adjacent inner floors 6 [resp. 11 the outlet pipe or hold the inlet pipe together with the opposite covers. In the inner chamber are between further inner floors partially perforated bores 2, 3 and 4 · clamped, one of which each with the input and Output pipe is in communication in such a way that there is an offset between the input and the output.

At the entrance to the muffler is the volume 14- and at the exit the volume 9 de of a Helmholtz resonator available, these volumes limited to the muffler inside by the partitions 6 and 11 will.

The associated resonator tubes 7, 7a, 7b and 12, 12a, 12b are fixed in the partition walls 6 and 11, respectively and usually mounted in such a way that their inlet openings are opposite one of the openings of the tubes 2, 3 or 4 lie. The tubes 7 lie with the opening 5 in each case opposite the inlet pipe and the pipes 12 with the opening to the connecting pipe which passes through the central chamber.

* ■

These known resonators only dampen in a relatively narrow frequency range and must therefore be equipped with suitable Dimensioning of volume and pipe dimensions can be matched to the frequency to be damped. The lower the The frequencies to be attenuated here are, the larger the volumes 9 and 14 must be, and of course also the Lengths of the tubes 7 or 7a or 12 or 12a. Because of these facts, the known arrangements of resonators a relatively large volume is always required and since the lengths of these volumes are therefore also very large the resonators take up too much of the

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available silencer volume for yourself. This then always has the effect of the Muffler in the other frequency ranges so deteriorated that one if from installation technical Reasons the silencer cannot be extended to the use of resonators have to do without.

If, on the other hand, one proceeds according to the proposal of the invention, then one can use sound attenuation Reach lower frequencies even with a short length of the volumes of the resonator chambers.

One design of a muffler according to the invention is in Pig. 3 shown in a cross section. A Jacket 20 is closed at both ends with cover 21 and 22 and through in its interior three partitions 23 »24-, 25 divided into four chambers, the chamber 26 lying between the cover 22 and the partition 25 serving as a resonator chamber. In the partition walls 23 and 24 provided with openings 27 tubes 17, 18 and 19 are used, wherein the ^ ear 17 a connection between the first and third Chamber produces, the tube 18 is pushed into the connecting tube 28 and the tube 19 into the connecting tube 29 is. The partition walls are provided with splashes on their outer edge, those on the inner surface of the jacket 20 and can be spot-welded to it. The partitions have to accommodate the various tubes have openings that are provided with flared collars, which is also the case with the lids, where the pipes pass through, is advantageous, so that

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the various pipes housed inside the silencer are reliably supported. The openings 27 in the walls of the pipes 17, 18 and 19 can either be bores of different design or outlets with pipe wall parts bent up in the shape of a roof, so-called blinds. In the resonator chamber 26, a resonator tube 30 is provided, which has approximately the shape of a "V" and whose upper end 32 protrudes into the preceding chamber 31, while the subsequently curved and then straight part, i.e. the main length of this tube 30, extends transversely the chamber 26 extends

As a result, the tube 30 can be much longer than if it were parallel to the axis of the muffler, it would reduce the length of the resonator chamber 26 is pushed down to a minimum and the entire length of the muffler is much smaller is like using a straight pipe. So one has by using a curved one Tube 30 the required length of a resonator tube in housed a resonator chamber, which would be too short if the usual straight tubes were used.

The exhaust gas pulses and sound waves entering the muffler through one of the connecting pipes 28, 29 are dampened in the main part of the muffler in a known manner by reflections, throttling and the chain conductor effect of the pipe masses and volumes. The path of the exhaust gases is indicated by the dashed lines with arrows. Finally, the exhaust gases leave the silencer through the other connecting pipe 29 »28 as a direct flow with low pulsation waves and correspondingly low sound wave components.

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If the exhaust gas pulses coming from the engine enter the muffler through the pipe 29, they will arrive they through the bore 19 to the mouth 32 of the resonator tube JO and always excite the resonator to vibrations when the pulse frequency or a harmonic is in the tuning range of the resonator · The vibrations of the resonator then have the consequence that in the area of the inlet mouth of the Resonator tube and inside the chamber in which this' mouth is located, the stimulating impulses and sound waves are effectively attenuated, so that the relevant sound frequencies in the noise at the The mouth of the outlet pipe 28 largely disappears.

If the exhaust gas pulses enter the muffler through the pipe 28, they pass through the pipes and 17 as well as through the perforation 27 into the tubes and 17 into the chamber 31 and rain there upon entry in the tube 19 at the same time the resonator via the tube 30 to vibrate when the excitation frequency is in the range of resonator tuning. The oscillations of the resonator have in this Pail to The result is that in the area between the openings of the outlet tube 19 and the resonator tube 30 in the chamber the stimulating pulses and sound waves are effectively attenuated, so that the relevant sound frequencies largely disappear in the noise at the mouth of the outlet pipe 29.

In this way it has been achieved that long resonator tubes can be found in a relatively small space

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can use, so that in cases of particularly low frequencies a largely per damping has become possible is what was previously not feasible because of the insufficiently deep resonator tuning.

The muffler 20 '(FIG. 4) is designed essentially in the same way as the muffler shown in FIG. 3. The difference, however, is that in the resonator chamber 26 'a resonator tube 33 is accommodated in its entire length transversely to the longitudinal axis of the muffler within the short resonator volume 26'. At one end, the tube 33 is closed with a cover 34, but a pinch or a similar closure can also be provided there if necessary. The pipe 33 is attached to the partition 25 'in such a way that it is connected ^{to the adjacent silencer volume 31' via aligned openings 5 1} in the partition and in the wall of the pipe.

The mode of action of such in the rest just like the damper constructed and described in FIG. 3 is the same as indicated there.

Finally, in Fig. 5 it is shown that one to the same Effect can come if you have an elongated resonator tube 35 in such, otherwise similar in itself inserted silencer 20 'into the gas-carrying inlet pipe 19' ", so that its end 32 '*, for example, in a rather Cutting zone 36 of the pipe 19 ″ can be stored. The right end of the tube 35 protrudes again into the resonator chamber 26 ″.

The rest of the structure and the mode of operation are the same

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as with the designs described above. ,

But you can also, following the proposal of the invention, to a design with a particularly long resonator tube come when you use a combination of the embodiments according to Figures 3 and 5, wherein then the resonator tube protruding into the inlet tube 19 ″ 35 in the area of the chamber 26 * 'a bend obtained like the pipe 30 according to FIG. 3.

Finally, it should be noted that the proposed here long resonator tubes in the same or can accommodate various different designs in other places, as shown in Fig. 2a, 2b and 2c for the short pipe sockets 7 »12 removed can be.

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Claims (1)

Claims Silencer with one resonator chamber each at the beginning and / or end of the silencer and with a resonator tube of great length connected to each resonator chamber, characterized in that the resonator tube (30, 33 »35) in the area of its inlet opening in the resonator chamber directed towards the rest of the silencer volume -Partition wall is mounted and protrudes with the largest part of its length in the resonator chamber (26, 26 ', 26''), it has a bend to accommodate the length and in the area behind the pipe bend parallel or at a small angle, to the chamber partition (25, 25 ', 25 ¹¹ ) and thus transversely to the longitudinal axis of the chamber. 2) silencer, characterized in that the resonator tube (35) in the area of its resonance 'Volume-directed tube opening in the resonator chamber partition is stored and is with most of its length in the rest of the silencer volume extends, wherein it telescopes to accommodate its length in one of the gas-carrying Perforated tubes (19) protrudes and is mounted in this. 3) silencer, characterized in that the Reso- 309833/0291 natorrphr (33) is located entirely within the Resonator chamber (26 ') is located, being parallel to the chamber partition (25 *) runs, is attached to this, via corresponding against the resonator volume sealed openings in the pipe jacket and in the partition with the remaining volume of the silencer communicates and at his. the end adjacent to the coupling opening (32 *) is locked. Silencer according to claims 1 and 2, characterized in that the resonator tube (30) is inserted into the The resonator chamber (26 ') protrudes and extends in this with a bend and also telescopes into one the gas-carrying perforated pipes of the rest of the silencer volume extends. 5) silencer according to claim 1 to 4-, characterized in that the resonator tubes are round, oval or have angular cross-section and can also be designed as pressed parts. 6) Silencer according to claim 3 »characterized in that the resonator tube (33) located entirely in the resonator chamber (26") and attached to the partition (25 ") has a flattened cross-section with which it rests against the partition. 309833/0291 Empty line