FR2649237A1 - Process and device for the acoustic treatment of a room - Google Patents

Abstract

The invention relates to the acoustic treatment of noisy rooms. Use is made of a material which achieves an acoustic absorption effect 1 and interposed between this material and the space of the room to be treated is a stretched impermeable membrane 4 arranged in the vicinity of this material but at least partially spaced therefrom, so as to avoid any pollution of the space of the room by the absorbent material whilst enabling the latter, through its membrane effect, to perform its acoustic absorption function. Application to the treatment of rooms intended for the food industry in particular.

Description

PROCESS AND DEVICE FOR TREATMENT
ROOM ACOUSTICS
The present invention relates to the acoustic treatment of noisy premises capable of being used to shelter in particular an activity which is part of the food industry.

 It is known that the use of porous and / or fibrous materials is prohibited in the food industry for reasons of public health, in particular because of bacteriological problems.

 However, the known effective acoustic absorbent elements are of this type and therefore cannot be used, in particular for the installation of acoustic ceilings, or the treatment of walls.

 The present invention makes it possible to produce "food grade" absorbent acoustic baffles.

 It also applies to industries presenting similar constraints, for example to the pharmaceutical, space, nuclear industries, to the treatment of clean rooms, etc.

 According to the invention, a material is used which provides an acoustic absorption effect, and a substantially impermeable membrane, stretched and arranged in the vicinity of this material but at least partially spaced between this material and the space of the room to be treated, is interposed. this, so as to avoid any pollution of the space of the room by the absorbent material while allowing it, thanks to the membrane effect to ensure its acoustic absorption function.

 The acoustic vibrations are thus transmitted to the acoustic material which absorbs them substantially whereas any particle which may originate from this material cannot in any case be dispersed in the atmosphere of the room to be treated thanks to the impermeable membrane.

 On the other hand, the whole treatment being perfectly smooth, it has no surface roughness which could promote bacteriological development.

 We can say that the membrane is impervious to fluids but "permeable" to acoustic vibrations by membrane effect. The tightness allows the cabinet to be washed down with large amounts of water without affecting the acoustic qualities.

 The membrane can be made of resistant polyester while the absorbent element can be made of fibrous material such as glass wool.

 In one embodiment, the acoustic baffle comprises a plate of absorbent material associated with a stretched membrane disposed along this plate but spaced from and substantially parallel to the latter.

 In another embodiment, the acoustic baffle may comprise a bag whose wall constitutes the membrane and inside which a plurality of absorbent elements are arranged, the bag is closed in a sealed manner and so that the membrane of the bag is advantageously stretched.

The description which follows, given by way of example, will make it clear how the invention can be implemented.

Figure 1 is a schematic view of a first embodiment of the invention.

FIG. 2 is a schematic view of a second embodiment of the invention,
Figure 3 is a schematic view of a third embodiment of the invention.

FIG. 4 is a perspective view of the embodiment of FIG. 3.

Figure 5 is a view similar to that of Figure 3, illustrating an alternative embodiment.

FIG. 6 is a diagram representing the acoustic absorption obtained as a function of the frequency with an acoustic baffle according to the invention.

In FIG. 1, one can see an acoustic baffle comprising a plate (1) made of sound absorbing material
(for example in fibrous and / or porous material such as glass wool) surrounded on its periphery by a frame (2) ensuring its maintenance. This frame can be made of plastic, steel, stainless steel, or any other conventional material. It is provided with elastic peripheral beads (3).

 A membrane (4) is stretched around the frame (2) and rests on the beads (3) thereof. The membrane can for example be made of resistant polyester, such as the material sold under the name of MYLAR, with a thickness of 5 to 25rC. It is closed at (5) in a leaktight manner by any appropriate means (bonding, heat-sealing, etc.) The membrane (4) therefore extends on either side of the plate substantially parallel to the latter, preferably at a distance greater than or equal to 5 mm, for example 1 cm. It has no point of contact with the absorbent element (1). It is thus confined in a perfectly sealed enclosure limited by the membrane (4).

 Advantageously, the assembly is surrounded by an external frame (6) also provided with beads (7) similar to the beads (3). This frame constitutes a casing making it possible to adapt the aesthetics and ergonomics to each case encountered.

On the other hand the beads (7) cooperate with the associated beads (3) to come by pinching the membrane.
(4) increase tension.

Thus it is capable of ensuring the desired membrane effect.

The external acoustic vibrations are therefore transmitted, via the membrane to the element (1) which absorb them substantially. On the other hand, no communication exists between the enclosure containing the absorbent element and the exterior thereof. Any pollution of the atmosphere of the room to be soundproofed by the absorbent element is therefore avoided.

FIG. 6 illustrates the actual sound absorption obtained with an acoustic baffle according to the invention, as a function of the frequency F In the example chosen, the membrane is a MYLAR polyester sheet of 23Wnet the absorbent element is a woolen plate, . 80 mm thick glass.

The baffle which has just been described can be used for the production of "acoustic" ceilings or walls, while meeting the standards required in the food industry.

 It goes without saying that in the case where only one side of the cabinet is in contact with the atmosphere of the room to be treated, the membrane could only be associated with one side of the absorbent element, the other side can be embedded or glued to the wall of the room to be treated.

On the other hand, it is possible in a variant that is not (shown) to use absorbent elements constituted, in a similar manner, by several plates of glass wool separated by one or more air knives. For example, pn may have 25 mm of glass wool, 30 mm of air, 25 mm of glass wool.

FIG. 2 illustrates a variant of the embodiment of FIG. 1.

Each edge of the absorbent plate (1) is associated with a clamp (11) whose ends are supported on the sides of the plate and whose bottom extends substantially parallel to the edge of the plate and at a short distance from it. this. In some cases the bottom of the pliers can rest on the edge of the plate.

The membrane (4) surrounding the assembly is stretched over the clamps which keep it away from the plate 1. It is closed at (12) in a leaktight manner.

The finish and the ergonomics of the assembly are ensured by the installation of a peripheral frame which can be in metal, plastic etc ... fixed by gluing or any other appropriate means.

Figures 3 and 4 illustrate another embodiment of an acoustic baffle according to the invention. It consists of a bag (13) for example of parallelepiped shape which can be closed at (14). The wall of the bag can consist of a resistant polyester membrane. Inside this bag are arranged absorbent elements (15), for example of cylindrical shape, so as to fill the bag as much as possible and to stretch the wall of the bag. The bag is closed at (14) in a leaktight manner. The absorbent elements can be made, for example, of glass wool, foam, etc. We thus obtain
If an entirely smooth acoustic baffle, usable in the food industry and presenting the acoustic efficiency of the absorbent elements thanks to the membrane effect.

The elements can be chosen in various colors and shapes according to aesthetic and ergonomic needs.

The baffles can be suspended from the ceiling by means of rods penetrating into eyelets (16) or other means of attachment practiced on the closure (14).

In the variant of Figure 5, the absorbent elements (15) have a parallelepiped shape. Other forms of the elements (15) can be provided, in particular oval sphericals, etc., without going beyond the ambit of the invention.

Claims (11)

 1) Process for the acoustic treatment of a noisy room capable of being used to shelter in particular an activity forming part of the food industry, characterized in that one uses a material (1,15) providing an effect of sound absorption and that there is interposed between this material and the space of this room a membrane (4,13) substantially impermeable, stretched and disposed in the vicinity of this material but spaced at least partially from it.  2) Device for the acoustic treatment of a room intended in particular to house an activity which is part of the food industry, characterized in that it comprises at least one absorbent element (1.15) confined in an envelope constituted in part at less by a substantially impermeable, more or less stretched membrane (4,13), disposed in the vicinity of this material but at least partially spaced from it.  3) Device according to claim 2, characterized in that the membrane has a thickness of substantially between 5 to 25  4> Device according to claim 2 or 3, characterized in that the absorbent element is made of a fibrous material such as glass wool.  5) Device according to any one of claims 2 to 4, characterized in that it comprises at least one absorbent element (1) in the form of a plate and that the stretched membrane (4) is disposed along this plate but spaced of and substantially parallel thereto.  6) Device according to claim 5., characterized in that it comprises a frame (2) holding the absorbent element on its periphery and around which the membrane is stretched, the latter having no point of contact with the element absorbent.  7) Device according to claim 6, characterized in that the frame is provided with peripheral elastic beads (3) on which the membrane (4) rests.  8) Device according to claim 7, characterized in that it comprises a second frame (6) outside surrounding the first (2) and also provided with beads (7) cooperating with the first (3) to increase the tension of the membrane (4) by pinching.  9) Device according to claim 5, characterized in that the edges of the absorbent plate (1) are associated with clips (11) whose ends are supported on the sides of the plate and whose bottoms extend substantially parallel at the corresponding edges of the plate and at a short distance from or against them, the membrane (4) being stretched over the clamps (11) which keep it away from the plate (1).  10) Device according to any one of claims 2 to 4 characterized in that it comprises a bag (13) whose wall constitutes the membrane and inside which are arranged a plurality of absorbent elements (15), the the bag being closed in a leaktight manner and so that the metallurgy constituting the wall of the bag is stretched.  11) Device according to claim 10, characterized in that hooking means (16) are arranged in the closure strip (14) of the bag so as to allow the device to be suspended from the ceiling of the room to be treated.