WO2003008237A1

WO2003008237A1 - Soundproofing element

Info

Publication number: WO2003008237A1
Application number: PCT/EP2002/006106
Authority: WO
Inventors: Franz Schweiggart; Franz Koch; Dimitrios Patsouras; Klaus Pfaffelhuber
Original assignee: Faist Automotive Gmbh & Co. Kg
Priority date: 2001-07-17
Filing date: 2002-06-04
Publication date: 2003-01-30
Also published as: DE10134783A1; DE10134783B4; ES2235081T3; ATE283181T1; DE50201635D1; EP1406792A1; EP1406792B1

Abstract

To improve the absorption of sound, a plate (1) comprising numerous small perforations (2), or a layer with a low hole-surface ratio is used as a front cover for a system (3) of chambers (4), the latter being separated from one another by partition walls (5). Said partition walls (5) run essentially perpendicular to the plate (1).

Description

Shawl screen element

The invention relates to a sound shielding element with at least one plate having many small openings, according to the preamble of claim 1.

Such sound shielding elements, which are used, for example, to protect against sound propagation from the noise area of a room into a neighboring room and / or to cover sound-reflecting or sound-generating components, are already known (WO 00/68039). The dimensioning of the mean diameter or of the small openings formed as holes, slots or the like is just as important as the proportion of the area which has such openings on the entire surface of the sound shielding element. This so-called “perforated area ratio”, like the average diameter or the width of the perforations, should be very small. Perforated area ratios between 0.01% and 10% and average diameter or width of the perforations between 0.01 mm and 1 mm are preferred.

Challabschirmelementen in such _S, it is also known that several such comparable with many small openings arrange the panels in parallel one behind the other in front of the sound-reflecting wall, for example, and keep them at a distance by spacers.

In addition, it is also known (DE -AS 1 180 155) to equip a soundproofing panel consisting of at least three layers with perforated front panels and a hardboard inserted between the front and rear panels in a sandwich-like manner; Large holes are also provided, which go through the 3-plate system and primarily serve for ventilation.

In the case of sound-insulating, plastic-molded components, it is also known (US Pat. No. 4,479,992) to mechanically stabilize strongly projecting thin wall parts by providing them with a honeycomb-like stiffening structure on the back.

The invention has for its object to further improve sound shielding elements of the type mentioned in terms of their sound absorption in the simplest possible manner and with low manufacturing costs.

The invention is characterized in claim .1 and in further subclaims and in the description preferred forms of training are claimed or. described.

It has very surprisingly been found that the sound absorption can then be improved according to the invention, when behind d _e r _P latte a system of chambers is arranged welc _{he d} urch partition walls are separated from each other. The plate _e _d i nt _d ann _g ewissermaßen as a front cover of the Chamber m _e rsys _t ems, egg _b which the partition walls at substantially accounting- angle to the plate. Such a "box or. Cassette system "is shown schematically in Figure 1. Measurements have confirmed that the equivalent absorption area, which represents a measure of the absorption especially in the audible sound wave range, can be improved considerably and for certain frequency ranges by a multiple. These results were not predictable , even if it was known to arrange perforated material, in particular made of foam, between a perforated outer layer and a rear cover plate (US Pat. No. 3,770,560) Have essentially circular chambers in, for example, plastic, which are either covered with a thin, oscillatable cover film or with a front plate which has an opening for each Helmholzt chamber.

In the invention, the chambers are preferably rectangular in cross section, so that the partitions each run in a substantially straight plane, which greatly facilitates the production of large-area sound shielding elements. However, the partitions can also be honeycomb-shaped or be formed by tube pieces placed against one another. The chambers should have a clear width between 10 mm and 300 mm. The partitions should be as thin as possible; wall thicknesses between 0.5 mm and 3 mm are recommended.

Polypropylene is particularly recommended as the material for the partition walls in a cased underbody paneling of motor vehicles. In high temperature applications, metals, e.g. B. Aluminum, advantageous for the partitions. A perforation area ratio of between 1% and 8% is particularly preferred for the plate and the average diameter or the width of the small openings should be between 0.05 mm and 1 mm. The system of chambers and partitions should connect to a rear wall on the side facing away from the plate; this can also be designed as a plate. The back wall can also be missing.

The chambers are preferably filled with air. It is assumed that the air vibrations behind the "perforated plate" provided with small openings, in particular small circular holes, are influenced by the partition walls arranged as "transverse walls" in such a way that a considerably larger proportion of "sound energy" is dampened in the microperforated plate in front of it ,

A preferred embodiment of the invention is described below with reference to the drawing. Show:

Figure 1 is a schematic partial view (partially torn) of a sound shielding element according to the invention and

Figures 2 and 3 curves for the equivalent absorption area in m ² depending on the measurement frequency f in Hz.

According to FIG. 1, a system 3 of chambers 4 is arranged behind the plate 1, which is provided with small openings 2, which are formed by partitions 5 which extend orthogonally to the plate 1. The chambers 4 are _d in this example in cross section quite angular, in particular square, with a width B and a depth T. between the back of the plate 1 and the rear wall 6, which may also consist of a plate. However, this rear wall can also be omitted, which surprisingly hardly changes the absorption behavior. The partition walls 5 have the smallest possible wall thickness S, which above all has to ensure sufficient stability of the, in particular, self-supporting chamber system A of “cassettes”.

In an embodiment subjected to measurements, the wall thickness d of the plate 1 is approximately 2 mm. Hole diameters D of 0.8 mm are used and the hole area ratio, i.e. H. the proportion of the area occupied by the holes in the total area of the plate 1 is 0.5%. The chamber system 3 has a depth T of 30 mm. The chamber or partition walls 5 with a wall thickness S of 2 mm are made of polypropylene.

Their width B is given in the table below. The plate 1 consists of transparent injection molding; it has a wall thickness d of 2 mm.

In the present embodiment, the chambers 4 have the height H and the width B. The dimension of the entire measured arrangement is 1 ^ 200 mm x 800 mm

W (mm) H (mm)

A 800 1,200 B 400 400 C 200 200 D 100 100 E 50 50 F without chambers, only with spacer bolts In Figure 2, the equivalent absorption area (m ² ) (measured in the alpha cabin) as a function of the measurement frequency for examples A to F of the table, ie for different widths and heights of the chambers 4 is listed. If the perforated plate 1 is arranged without partition walls at a distance T from the rear wall 6, which can be realized by suitable spacers, the curve F results. With increasing width B and height H of the chambers 4, higher absorption values or α- Values reached. The equivalent absorption area is increased at 600 Hz to 600%, ie five times. Even at a frequency f of 8 kHz, the equivalent absorption area is still more than doubled.

FIG. 3 shows the dependence of the absorption curve on the “degree of cassette” with the same cassette measures as in the previous example, if a high-frequency tuning of the microperforation is selected. In contrast to FIG. 2, however, the distance, ie the depth T, is between the microperforated plate 1 and the rear wall B. only T = 20 mm Here, too, the cassette can achieve a significant improvement in absorption, even if the percentage increase is not as great as with deep tuning. The wall thickness d of plate 1 is d = 0.5 mm with slit-shaped Openings 2 of 0.1 mm width with a hole area ratio of 5%.

_Since he _f s indungsgemäße sound proofing element is n not only in äum _R _e, but also to shield machines and lärmverur _sa c _h forming units in motor vehicles applicable. Also Preferred areas of application arise in aircraft and in particular passenger ships in which the cabin area is to be particularly noise-protected.

The sound shielding element can be manufactured by, for example, the following preferred manufacturing processes in such a way that the partitions forming the chambers form a mechanical structural unit with the plate or layer covering the chambers:

1. A thermoplastic plastic film is heated from a heating field and then pulled, in particular by means of vacuum, into a deep-drawing tool forming the chambers. The film clings to the chamber contour and hardens by cooling. The perforations can be made by perforating the chamber bottoms that form the plate or layer using needle fields. This is either still possible in the deep-drawing tool or even after demolding. Instead of the vacuum deep-drawing process, a corresponding blowing process can also be used, in which the thermoplastic plastic film is pressed against the contour of the shaping blow molding tool by the blowing pressure.

2. Nonwovens, foams, foils or plastic masses are pressed into a chamber structure. Cold pressing of thermally heated thermoplastic materials or hot pressing of thermosetting materials is possible. Here, too, the perforations can Per _f orieren subsequently a _g e _b racht be either in the pressing tool itself or. In addition, it is also possible to find in advance in accordance with "perforated" material v _e r _f ormen. This can be a thin fleece application which has an average opening proportion and an average opening diameter, which correspond to the design rules for the openings of the preamble of claim 1.

A component integrating the plate or the layer on the one hand and the partition walls of the chamber on the other hand can also be produced by casting, injection molding, injection molding or injection molding. It is also recommended to use the same material for the plate and partitions. According to a preferred embodiment, the partition walls with the chamber structure, in particular polypropylene, are injection molded onto a perforated, in particular needle-rolled, film made of polypropylene, in particular an aluminum polypropylene composite layer.

Claims

Claim version

1. A sound shielding element with at least one plate (1) or layer with a large number of small openings (2) or a thickness d between 0.001 mm and 50 mm, in which the average diameter or the width of the opening (2) between 0.001 mm and 2 mm and the hole area ratio between 0.01% and 8%, characterized in that the plate (1) is used as a front cover for a system (3) of chambers (4) which are separated from one another by partitions (5) and run essentially at right angles to the plate (1).

2. Sound shielding element according to claim 1, characterized in that the chambers (4) are rectangular in cross section and the partitions (5) each extend in a substantially straight plane.

, A sound proofing element according to claim 1 or 2, characterized GEK _e NNZ _e ichnet that the partitions (5) intersect at right angles.

4. Sound screening element according to one of the preceding claims, characterized in that the chambers (4) have a clear width B between 5 mm and 300 mm.

5. Sound screening element according to one of the preceding claims, characterized in that the partitions (5) have a wall thickness S between 0.5 mm and 4 mm.

6. Sound screening element according to one of the preceding claims, characterized in that the perforation area ratio of the plate (1) is between 1% and 8%.

7. Sound screening element according to one of the preceding claims, characterized in that the average diameter or the width of the openings (2) is between 0.05 mm and 0.7 mm.

8. Sound screening element according to one of the preceding claims, characterized in that the plate (1) consists of an aluminum-polypropylene composite.

9. Sound screening element according to one of the preceding claims, characterized in that the partitions (5) consist of polypropylene.

10. Sound screening element according to one of the preceding claims, characterized in that the system (3) of chambers (4) and partitions (5) on the side facing away from the plate (1) connects to a rear wall (6).

11. _S challabschirmelement according to claim 10, characterized in that the rear wall (6) is designed as a plate.

12. A sound proofing element according to one of .vorhergehenden An ^¬ claims, characterized in that the plate (1) are formed integrally with the partition walls (5).

13. A sound proofing element according to claim 12, characterized labeled in ^¬ characterized in that the partitions (5) swaged with the plate ⁽¹⁾ made of a plastic film and / or ren in Blasverfah- is made.

14. A sound proofing element according to claim 12, characterized in that the chambers ^⁽⁴⁾ forming partitions _₍₅₎ are injection-molded onto the plate (1) which consists of a needle-rolled foil.

15. A sound proofing element according to claim 14, characterized labeled in ^¬ characterized in that the needle-rolled foil consists of an aluminum-polypropylene composite.