DE29623522U1 - Sound absorbing component - Google Patents

Description

Telephone: +49-89-21 9912-0 Fax: +49-89-21 9912-20 e-mail: upon request Telegramm/cable: MAXIMARK® Munich

PO Box 10 11 61 Maximilianstrasse 6 D-80085 Munich

Hans-Jürgen Müller Gerhard D. Schupfner Hans-Peter Gauger Patent attorneys European Patent Attorneys European patent attorneys

8101. GM-DE HJM/MY

M. Faist GmbH & Co. KG Michael-Faist-Strasse 11-15

D-8 6381 Krumbach

"Sound-absorbing component"

(from 196 34 615)

MAXIMARK Foray 01

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Hans-Jürgen Müller Gerhard D. Schupfner Hans-Peter Gauger Patent Attorneys European Patent Attorneys European patent attorneys

Telephone: +49-89-21 9912-0 Fax: +49-39-21 9912-20 e-mail: upon request Telegram: MAXIMARK® Munich

PO Box 10 11 61
Maximiiianstrasse 6
D-80085 Munich

M. Faist GmbH & Co. KG 8101. GM-DE HJM/S&zgr;

SOUND ABSORBING COMPONENT

The invention relates to a sound-absorbing component, in which chambers have thin side walls and form acoustic resonators.

Such a "sound absorber" is already known (DE-OS 195 29 440, EP 0 683 480 A1 and DE 94 14 934 U1). For example, rectangular or cylindrical, cup-like depressions are formed from a film using a deep-drawing process and connected to a carrier body. On the open side facing the sound incidence, such absorbers can be covered with a liquid-tight cover layer so that no foreign particles or contaminants collect in the resonator chambers. It is also known to form the chambers using flexible hoses that are attached to the underside of such a cover layer. Although such sound absorbers have proven to be functional, their production is relatively complex.

In addition, it is also known (DE 43 34 984 Cl, DE-U 69 48 849 and EP 0 214 559 A3) to line chambers formed in foam with thin foils in order to protect the porous

To protect the chamber side walls against contamination. Here too, the production is relatively complex.

The invention is based on the object of further improving sound-absorbing components of this type with regard to their sound-absorbing or sound-damping effect while simplifying their production.

According to the invention, the thin side walls of adjacent chambers, in contrast to the above-mentioned prior art, are not arranged at a greater distance from one another, but rather they lie close to one another or are preferably integrated with one another to form a partition wall, each of which is assigned to more than one chamber. The chambers therefore form a compartment-like chamber system with the partition walls, in which the chambers forming a kind of shaft are only separated from one another by the respective partition walls, i.e. they run directly next to one another. This chamber system is very stable and therefore ensures that the desired absorption spectrum or sound insulation frequency is maintained.

According to a special embodiment of the invention, the chambers are arranged next to and behind one another in such a way that they form a type of honeycomb system in the chamber plane, even if the respective chamber cross-section is not hexagonal, in contrast to honeycombs, but square, in particular rectangular and above all square.

Functionally, there is also the advantage that the available space is filled with an optimal number of chambers, since the chambers are only separated from each other by the thin partition walls, which preferably have a film layer thickness or double film layer thickness in the order of 0.1-5 mm.

point.

Although the component according to the invention can be cast or injection molded in one piece, whereby the use of thermosetting plastics or, even better, thermoplastics is recommended, according to a special embodiment of the invention, production takes place using a deep-drawing process. In this case, by placing a deep-drawing tool, particularly one that is a grid, on a film, it is ensured that the grid bars pull the relevant film parts on which they rest out of the film plane using heat and pressure, or the film is pulled around and away from the grid bars so far that the connecting parts between the parts on which the bars rest and the raised film parts form the partition walls; in this case, film parts lie against one another as side walls of adjacent chambers; they can even fuse together. In a special embodiment, the grid is formed three-dimensionally.

In addition to the functional advantages mentioned above and the process-related advantages described here, the material requirements are also low and the floors of the chambers ensure that no contamination or moisture can penetrate into the chambers without the need for additional covering foils. The floors made of foil are so thin that they act like membranes and allow sound from outside to pass through into the chambers. There, in conjunction with the partition walls and, if necessary, a support on which the free ends of the partition walls rest, a spring-mass system is formed which dampens certain frequencies of sound energy. By choosing the material for the component and by selecting the size of the chambers and the material thickness of the partition walls and floors, certain frequency ranges can be dampened particularly strongly.

or is it possible to dampen a relatively broad frequency spectrum of the sound energy. If a certain film material has proven to be suitable for the floors and partition walls of the chambers of the component, it is only necessary to measure the distances between the bars of the grid used for deep drawing and the extent to which they deep draw the relevant film parts out of the film plane, in particular perpendicular to the film plane, according to the desired frequencies.

The rods used for deep drawing can be removed by separating the ends of the partition walls, especially the thick ones. For some applications, however, it is recommended to use so-called "lost grids" as deep drawing tools, so that the rods remain in the ends of the partition walls. This leads to improved stability of the entire component, as is required for use as a hood absorber, for example. In this case, it is recommended that the rod material is made of the same or similar material as the film or plate from which the deep drawing is carried out. The invention is not limited to the use of thin films, but plates that are thicker than films can also be used.

If the sound-absorbing or damping effect in special cases is to be improved, it is recommended according to a further development of the invention to pull the floors of the chambers onto sound-absorbing layers, in particular damping fleece. The film could also be pulled onto an aluminum strip coated with e.g. polypropylene, which acts as a heat shield. To reinforce the sound-absorbing component, it can also be useful to attach reinforcing elements, such as reinforcing grids, to the floors of the chambers and, if necessary, to place the reinforcing elements between

the floors and the additional sound-absorbing and/or heat-repellent layer. Such reinforcing elements can be formed by a fabric and it is recommended that thermoplastically bonded fibers are used for the reinforcing elements or a reinforcing mat.

Preferred embodiments of the invention will now be explained in more detail with reference to the figures.

Figure 1 shows a schematic partial cross section through a sound-absorbing component 1 according to the invention;

Figure 2 shows an enlarged partial section through a further embodiment of the invention;

Figure 3 shows a schematic cross section through a component according to the invention connected to a carrier 2, the outer side of which facing the sound incidence, which is formed by the floors, is not only located in one plane;

Figure 4 shows a cross-section corresponding to Figure 3, in which the carrier 2 is located in different planes;

Figures 4a, 4b and 4c show in cross section various deformation stages during the manufacturing process of a component according to the invention,

Figure 5 shows a further schematic cross section through a component according to the invention in a further process stage and

Figure 6 is a plan view of a cutaway part of the construction

part.

According to Figure 1, the component 1 is formed by a plurality of chambers 14, which are arranged next to and possibly one behind the other (not shown in Figure 1). The chambers 14 are each separated from one another by partition walls 4. At the outer edge, the component 1 is closed off by a flange 6, which extends in the plane of the thickened partition wall ends 5 and can serve as a fastening means on, for example, a support 2 (see Figure 3). The floors 13 of the chambers 14 face the sound incidence, which, like the partition walls 4, are made from a film 3 using a deep-drawing process. The sound incidence is symbolized by the arrows, which are provided with the letter "S".

According to Figure 2, the floors 13 are covered on the side facing the sound incidence with a fleece 12 that additionally dampens sound waves. A reinforcement grid 15 is used for reinforcement, which is inserted between the floors 13 or the film 3 and the fleece 12 and can be thermally welded together with the fleece 12 and the film 3. In this embodiment, the thickened partition wall edge 5 is cut open by a slot 8 that leads into the inner area 7, from which rods (no longer shown here) are taken through the slot 8, which form parts of a deep-drawing tool.

In the embodiment of Figure 3, the chambers 14 are not the same size, but chamber bottoms 13a are located at a smaller distance from the carrier 2 than other chamber bottoms 13. The cross-sectional width of chambers 14 is also chosen differently, so that different sound frequencies are "damped" due to the spring-mass effects.

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In the sound-absorbing component according to Figure 4, the support 2 is not located in a flat plane; rather, the outer surface of the support 2 facing the sound-absorbing component extends in different and partially mutually inclined planes. The thickened partition wall ends 5 are supported on corresponding surface parts of the support 2 according to Figure 4. The partition walls 4 extend between such partition wall edges 5 and the floors 13 of the "membrane absorber" facing the sound incidence S, forming the chambers 14 between the floors 13, the partition walls 4 and the surface of the support 2. This means that the thickened partition wall ends or partition wall edges 5 are also not located in a flat plane, but are adapted to the outer contours of the support 2, which is already taken into account in the manufacturing process of the component.

A particularly simple manufacturing process is demonstrated using Figures 4a to 4c as follows:

A thin film 3 made of PP (polypropylene) with a thickness of 1-5 mm is pressed from below onto rods 9 as shown in Figure 4a, which are combined in the form of a grid with grid rods arranged at right angles to each other. In this "initial stage" of the manufacturing process as shown in Figure 4a, the film 3 is in a single flat plane.

The heated film 3 is then pulled upwards in the direction of the arrow with fixed rods 9 or a fixed grid made of these rods 9 as shown in Figure 4b, whereby parts of the plastically deformable film 3 in the area of the rods 9 form grooves or folds 3a.

According to Figure 4c, the final "deep drawing stage" is schematically

shown, in which the film 3 was pulled out from the original plane A of Figure 4a into the final plane E at a distance from A. The rods 9 are located inside the thickened edge 5 of the partition walls 4, which are formed from a double layer of the film parts pulled out from the film plane E here at right angles. The folds 3a of Figure 4b are considerably longer and have become the partition walls.

4 are placed together between the chambers 14 formed thereby.

The bars 9 can remain in the partition ends 5. The "deep-drawn grid" formed from the bars 9 is then a "lost grid" in this embodiment, which on the one hand makes the use of a further process step superfluous, but on the other hand also serves to reinforce the edge areas

5 of the Chambers 14 contributes.

If such reinforcements and "lost grids" are not desired, according to the embodiment of Figure 5, it can also be ensured that the thickened partition ends 5 are separated and the rods 9 are removed by a tool 11. In the embodiment of Figure 5, the film level E is at the bottom, so that the tool 11 would have to make an upward movement in the direction of the arrow 0 to remove the rods 9. The grid formed from the rods 9 can either be cut out of the partition ends 5 with a punching knife located in the upper punch of the deep-drawing machine or it can also be melted out by heating the edges of the partition. After the manufacturing process has been developed, the film 3 is pulled by an upper punch over the grid onto the sound-absorbing fleece 12 mentioned above and with this onto a type of "deep-drawing bed". The film 3, which is held by a frame not shown here, is moved from top to bottom over the grid towards the "deep-drawing bed". This causes film

areas to form the partition walls 4 are also pulled downwards and at the same time the chambers 14 are formed. The thickened partition wall edges 5 are then at the top, so that an upper punch moves downwards from above, for example as shown in Figure 5, and cuts open the upper parts of the partition wall ends and penetrates as far as the bars 9. When the upper punch moves back upwards, the grid bars 9 are pulled upwards and removed from the component 1.

Figure 6 shows a schematic oblique view of such a component 1 composed of a chamber system.

The material for the component is not limited to plastic or thermoplastic. It is also possible to use a thin aluminum foil and to form a corresponding chamber system by deep drawing.

Preferred applications of the inventions are in the area of engines, in particular motor vehicle engines. There, the engine capsule or the hood panel can serve as a carrier on which the component according to the invention is placed with the free partition wall ends and connected by welding, gluing, clipping and the like.

Claims (10)

'··"··""rtänsOürgen lOlüller ' Gerhard D. Schupfner Hans-Peter Gauger Patentanwälte European Patent Attorneys Mandataires en brevets europeens Phone: +49-89-219912-0
Fax: +49-89-21 9912-20
e-mail: upon request
Telegram/cable:
MAXIMARK® Munich PO Box 10 11 61
Maximilianstrasse 6
D-80085 Munich 8101. GM-DE M. Faist GmbH & Co. KG HJM/MY PROTECTION CLAIMS 1. Sound-absorbing component in which chambers (14) assembled into a compartment-like chamber system have thin side walls and form resonance chambers or acoustic resonators and a deformed film (3) is used to form the side walls, characterized in that the film (3) is deformed such that thin side walls of adjacent chambers (14) abut one another as dividing walls (4) thereof. 2. Component according to claim 1,
characterized in that the bottoms (13, 13a) of the chambers (14) face the sound incidence. 3. Component according to claims 1 or 2,
characterized in that the bottoms (13, 13a) of the chambers (14) consist of foil (3) and act as a thin membrane. 4. Component according to one of the preceding claims, characterized in that the partition walls (4) have thickened partition wall ends (5). O MAXIMAEK Form 01 5. Component according to one of the preceding claims, characterized in that the floors (13, 13a) are covered on their outside with a sound-absorbing or sound-damping and/or with a heat-repellent layer (12). 6. Component according to claim 5,
characterized in that the sound-absorbing or sound-damping layer (12) consists of a fleece. 7. Component according to claim 6,
characterized in that the sound-absorbing or sound-damping layer (12) consists of foam. 8. Component according to claim 7,
characterized in that a reinforcing mat (15) is inserted between the floors (13) of the chambers (14) and the fleece. 9. Component according to claim 8,
characterized in that the reinforcing mat (15) comprises thermoplastically bonded fibers. 10. Component according to one of the preceding claims, characterized in that the partition wall ends (5) are connected to a support (2).