EP2898196B1 - Silencer and process for its manufacture - Google Patents

Description

The invention relates to a silencer with at least one bag and corresponding method for producing the aforementioned.

A muffler is a device for reducing noise emissions. There are various types of mufflers that reduce the generated sound power due to different mechanisms of action. An absorption silencer contains porous material, usually rock wool, glass wool or glass fiber, which partially absorbs the sound energy, that is, converts it into heat. The effect of sound absorption is enhanced by the multiple reflection. The invention particularly relates to such mufflers. Such silencers for internal combustion engines, in particular of vehicles or trucks, have a perforated inner tube for passing the exhaust gases. This is done in an outer air, dirt and moisture-tight sheath, so that forms a cavity between the inner tube and sheath. This cavity is filled with a sound-absorbing or -absorbierenden filling. The filling must be heat resistant. The filling of the cavity is complex and it is therefore resorted to prefabricated, flexible or more or less dimensionally stable elements with sound-insulating filling.

For example, dimensionally stable glass fiber basalt wool and multicomponent moldings are known, which contain flammable components that retain their shape during the first use of the silencer.

Pouches are known for insertion into a muffler cavity intended for sound deadening or absorption, with a shell closed on all sides, with a sound-absorbing or absorbing filling, the envelope consisting of plastic films or meshes. After filling these are welded. WO 2005/049982 revealed as well FR 2 906 307 A1 a pouch for insertion into a sound attenuator or cavity of a silencer having a knitted tubular casing and having a sound absorbing or absorbing filling, the casing being made of glass fibers. The filling is introduced into the shell and the shell is then closed at its ends. It is not disclosed to make certain 3D shapes.

DE 203 05 409 U discloses a bag for insertion into a muffler or cavity of a muffler having a tubular non-heat resistant envelope and having a sound absorbing or absorbing filling. The filling is introduced into the shell and the shell is then closed at its ends. It is not disclosed to make certain 3D shapes. The shell burns during operation of the muffler.

US 6,068,082 discloses a lattice-like member for insertion into a sound attenuation or absorption cavity of a muffler having a heat resistant shell and having a sound absorbing or absorbing filling. The filling is introduced into the shell and the shell is then closed.

GB 2 267 731 discloses a flexible bag for insertion into a sound attenuation or absorption cavity of a muffler with a fusible envelope and with a sound absorbing or absorbing filling. It is disclosed, inter alia, to put the bag around the inner tube of the muffler.

It is an object of the invention to provide a muffler with an improved bag for insertion into a cavity of a muffler or a muffler provided therewith and suitable methods for producing the same.

This object is achieved by silencers with the features of claims 1 to 8 and by a method for manufacturing the silencer according to the independent claim 9. Advantageous further developments are the subject of the dependent claims.

A silencer, in particular for internal combustion engines, preferably for vehicles or trucks, with a perforated inner tube for passing exhaust gases, an outer air, dirt and moisture-proof sheath and a cavity formed between inner tube and sheath has been developed according to the invention to the effect that at least one bag with a shell closed on all sides and with a sound-absorbing or absorbing filling in a cavity of the muffler intended for soundproofing or absorption, the envelope comprising intermeshed glass fibers, in particular a glass fiber knit, passing the filling through a loop in the envelope of the bag blown into the interior of the bag, and the closed on all sides Shell further comprising passages which are adapted to the outer cross section of the inner tube of the muffler, wherein the inner tube extends through the passage in the shell.

As already known from the prior art, the proposed bag for insertion into a designated for sound damping or absorption cavity of a muffler initially comprises a closed-all side shell with an enclosed therein sound-absorbing or -absorbierenden filling. Under a closed shell according to the invention is not a dense, for example, water, dirt or pressure density understood, such as a film. The term "closed" simply means that during transport, during normal handling, and when inserted into the cavity of the muffler, in the manufacture thereof, the envelope is impermeable to the filling placed therein. The special feature of the invention consists in the fact that the sheath consists of glass fibers and the filling is blown through the envelope of the bag into the interior of the bag. Thus, it is possible for the first time to provide a compact filling for labor-saving insertion into the cavity of a muffler, which releases no toxic combustion gases when first using the muffler. For the production of the bag while fewer steps are needed because the bag does not need to be closed after filling.

Another aspect of the invention, which can be implemented independently of or in conjunction with the invention described above, is that in the generic bag, the all-sided closed envelope has bushings. This allows adaptation to the geometry in the interior of the cavity, for example at indentations. The above-mentioned implementation in the shell can therefore absorb the indentation. It is therefore no manual adjustment by pressing / inserting individual bags needed. Preferably, however, the implementation is adapted to the outer cross section of the inner tube of the muffler. The bags can then simply be pushed over the inner tube. In the prior art, however, it was necessary to wrap individual bags around the inner tube or to lay several bags around the inner tube. This aspect of the invention can be realized independently of the material used of the casing, that is to say also in the case of the above-mentioned bags known from the prior art, for example of plastic.

• Wenn die Hülle im Wesentlichen aus vermaschten Glasfasern, insbesondere einem Glasfasergestrick, besteht, ergibt sich eine dehn- und formbare Hülle. Dieser Aufbau hat unter anderem den Vorteil, dass geschlossene Hüllen, die nicht separat verschweißt, vernäht oder verschlossen werden müssen, in einem einzigen Arbeitsverfahren hergestellt werden können. Es ist daher ein Merkmal, dass die Hülle frei von Nähten ist. Als Maschenware werden textile Flächengebilde bezeichnet, bei denen eine mittels Faden gebildete Schleife in eine andere Schleife hineingeschlungen ist. Die auf diese Weise entstehenden Maschen können unter Verwendung eines oder mehrerer Fäden gebildet werden.

The following advantageous embodiments apply to both inventions:

• If the sheath consists essentially of intermeshed glass fibers, in particular a glass fiber knit, results in a stretchable and malleable shell. One of the advantages of this construction is that closed casings, which do not need to be welded, sewn or closed separately, can be manufactured in a single operation. It is therefore a feature that the sheath is free of sutures. As a knitted fabric textile fabrics are referred to, in which a loop formed by means of thread is looped into another loop. The resulting stitches may be formed using one or more threads.

The mesh size or size of the meshed glass fibers is therefore to be chosen so that the components of the filling are initially well inflated by a mesh of the shell and the usually after blowing an enlarged volume having filling after blowing no longer through the mesh can fall out. The mesh size is therefore preferably 2-9 mm, in particular 2.5-5 mm and in particular preferably 3 mm.

Preferably, the sheath closed on all sides is produced by a single working method, in particular knitting, preferably on a flat knitting machine. Flat knitting machines make it possible to produce complex structures, for example pullovers or closed pouches. Also, other, even higher temperature resistant threads can be used in the knitting process at desired locations. Known from the prior art fiberglass casings are made on circular knitting machines and therefore limited to tube shapes and must be closed manually or in a further step.

If the shell has a shape adapted to the cavity, the cavity is filled particularly tightly with the filling, without that laborious stuffing, fitting, impressions is necessary. Therefore, the sheath may preferably have over its length, width and / or height variable cross-sections, in particular steps, curves, bulges, constrictions and / or indentations. From the prior art, only comparatively simple, tubular or pillow-like forms have hitherto been known.

Preferably, the filling is wholly or partly made of heat-resistant rovings, fibers or yarns. These allow the inventively preferred blowing into the closed envelope of the bag. Roving is a bundle, strand or multifilament yarn made of parallel filaments (continuous fibers), which is mainly used in the production of fiber reinforced plastics (FRP) or fiber reinforced plastics, a subgroup composites. The cross-section of a roving is usually elliptical or rectangular. However, there are also rovings with a slight protective rotation (eg 10 turns / m), which makes the cross section rounder. Most commonly filaments of glass, aramid or carbon are grouped into rovings. These are easily inflated, for example by a mesh of the shell and increase their volume after blowing, so that they can not fall out through the mesh.

Because of their high heat resistance, the filling is preferably made of glass or basalt materials. Preferably, the sheath and / or the filling are heat resistant in the range of 400-1300 ° C, preferably 450-1100 ° C. The materials used are preferably E-glass, silica, glass fibers with Si0 ₂ content greater than 75%, ECR glass, S-glass, C glass.

Preferably, the shape of the bag is adapted to the cavity of a muffler so that the cavity can be filled well without the need for manual stuffing or fitting.

• Herstellen eines Beutels zum Einsetzen in einen zur Schalldämpfung oder - absorption bestimmten Hohlraum des Schalldämpfers, mit folgenden Schritten:
  • --- Herstellen der allseitig geschlossenen Hülle des Beutels aus Glasfasern durch ein einziges Arbeitsverfahren, insbesondere Stricken, vorzugsweise auf einer Flachstrickmaschine, wobei kein Vernähen erfolgt;
  • --- Einblasen einer schalldämpfenden- oder -absorbierenden Füllung durch die Hülle des Beutels hindurch in das Innere des Beutels,
  wobei die allseitig geschlossene Hülle (2) des Beutels ferner Durchführungen (21) aufweist, die an den Außenquerschnitt des Innenrohrs des Schalldämpfers angepasst sind, und
  das Innenrohr durch die Durchführung in der Hülle verläuft,
• Einsetzen des Beutels (1) in den zwischen Innenrohr und Ummantelung des Schalldämpfers gebildeten Hohlraum, insbesondere an die für den jeweiligen Beutel (1) vorbestimmte Stelle, an welche die Form des Beutels (1) angepasst ist.

The inventive method for producing the above-described muffler with bag comprises the following steps in the order given:

• Making a bag for insertion into a muffler cavity intended for sound attenuation or absorption, comprising the following steps:
  • Producing the envelope of the bag made of glass fibers, which is closed on all sides, by a single working method, in particular knitting, preferably on a flat knitting machine, whereby no sewing takes place;
  • Blowing a sound absorbing or absorbing filling through the envelope of the bag into the interior of the bag,
  the bag (2) of the bag closed on all sides further having passages (21) adapted to the external cross-section of the inner tube of the muffler, and
  the inner tube passes through the passage in the shell,
• Inserting the bag (1) in the cavity formed between the inner tube and the jacket of the muffler, in particular to the predetermined for the respective bag (1) point to which the shape of the bag (1) is adapted.

So there is no need for a separate step to sew the bag after the filling has been introduced.

Further advantages will become apparent from the following description and the accompanying figure. Likewise, according to the invention, the features mentioned above and even further can be used individually or in any desired combinations with one another. The mentioned embodiments are not exhaustive and have exemplary character.

FIG. 1 shows the bag 1 according to the invention for insertion into a designated for sound attenuation or absorption cavity of a muffler. Its all-sided closed glass fiber sheath 2 is made by means of a working method on a flat knitting machine and was not sewn. Inside the shell 2 is a sound-absorbing or -absorbierenden filling 3. This was blown through the shell, so by a mesh of the sheath forming knit fabric into the interior of the bag.

The closed on all sides sheath 2 has inside a passage 21 for pushing through the inner tube of the muffler. Their diameter is therefore adapted to the outer cross section of the inner tube of the muffler.

Claims (9)

1. Silencer, in particular for internal combustion engines, preferably for passenger or commercial motor vehicles, having a perforated internal pipe for passing through exhaust gases, an external shell that is air-tight, dirt-tight, and moisture-tight, and a cavity that is formed between the internal pipe and the shell,
   characterized in that
   at least one pouch (1) having a sheathing (2) that is closed on all sides and having a sound-damping or sound-absorbing filling (3) is inserted in a cavity of the silencer that is specified for damping or absorbing sound, wherein the sheathing (2) has intermeshed glass fibres, in particular a knitted glass-fibre fabric, the filling (3) is blown into the interior of the pouch through a mesh loop in the sheathing (2) of the pouch (1), and the sheathing (2) that is closed on all sides furthermore has ducts (21) which are adapted to the external cross section of the internal pipe of the silencer, wherein the internal pipe runs through the duct in the sheathing.
2. Silencer according to Claim 1, characterized in that the mesh loop size of the intermeshed glass fibres of the sheathing (2) of the pouch (1) is 2 - 9 mm, in particular 2.5 - 5 mm, and in particular preferably 3 mm.
3. Silencer according to one of the preceding claims, characterized in that the sheathing (2) of the pouch (1) is free of seams.
4. Silencer according to one of the preceding claims, characterized in that the sheathing (2) of the pouch (1) that is closed on all sides is produced by a single processing method, in particular knitting, preferably on a flatbed knitting machine.
5. Silencer according to one of the preceding claims, characterized in that the sheathing (2) of the pouch (1) has a shape that is adapted to the cavity, and in particular across the length, width, and/or height thereof has variable cross sections, in particular steps, rounded features, bulges, constrictions, and/or inversions.
6. Silencer according to one of the preceding claims, characterized in that the filling of the sheathing (2) of the pouch (1) comprises or is composed of heat-resistant rovings, fibres, or yarns, in particular from glass or basalt, wherein preferably the sheathing and/or the filling are/is heat-resistant in the range from 400 - 1300°C, preferably 450 - 1100°C.
7. Silencer according to one of the preceding claims, characterized in that the filling of the sheathing (2) of the pouch (1) as materials has E-glass, silica, glass fibres having a content of SiO₂ of more than 75%, ECR-glass, S-glass, C-glass.
8. Silencer according to one of the preceding claims, characterized in that the shape of the pouch (1) is adapted to the cavity of a silencer.
9. Method for producing a silencer according to one of Claims 1 to 8, said method comprising the following steps:

   - producing a pouch for inserting into a cavity of the silencer that is specified for damping or absorbing sound, by way of the following steps:

   ∘ producing the sheathing (2) of the pouch (1) that is closed on all sides from glass fibres, in particular by a single processing method, in particular knitting, on a flatbed knitting machine, wherein no sewing takes place;

   ∘ blowing a sound damping or absorbing filling into the interior of the pouch (1) through a mesh loop in the sheathing (2) of the pouch (1), wherein the sheathing (2) of the pouch that is closed on all sides furthermore has ducts (21) which are adapted to the external cross section of the internal pipe of the silencer, and
   the internal pipe runs through the duct in the sheathing,

   - inserting the pouch (1) into the cavity that is formed between the internal pipe and the sheathing of the silencer, in particular at that point that is pre-specified for the respective pouch (1) and to which the shape of the pouch (1) is adapted.

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