FR3043588A1 - MULTILAYER ACOUSTIC PANEL - Google Patents

Abstract

The invention relates to an acoustic panel (1) comprising a core (11) constituted by a honeycomb structure (111) closed only on one side by a structural layer (112), the core (11) being interposed between two outer layers (13A, 13B) of damping material, each damping layer (13A, 13B) being fixed on the core (11) by an adhesive layer (12A, 12B).

Description

Multilayer acoustic panel

FIELD OF THE INVENTION The invention relates to the general field of acoustics. The invention more particularly relates to a panel structure for correcting the acoustics of a room.

Such an acoustic panel may be used in buildings or premises in which acoustic correction is necessary, such as industrial or public buildings (conference rooms, theaters, classrooms, commercial premises, dining rooms, station halls, offices, hospitals ...).

2. BACKGROUND TECHNOLOGY The use of acoustic panels is common in environments with high noise levels, for example in office space, in public spaces or in dwellings.

Such acoustic panels arise in buildings as a partition or along a partition or ceiling, with or without space relative to the partition or ceiling. Such acoustic panels are designed to correct the acoustics of a room and reduce noise, so that the activity takes place in the best possible sound conditions.

These acoustic panels are conventionally constituted by an absorbent core made of glass wool or rockwool, provided, at least with apparent appearance, with a facing layer consisting of a fiberglass veil, which gives it a decorative finish. .

These acoustic panels are constantly being improved to increase their performance. However, this increase in performance is usually accompanied by a significant increase in their thickness, their weight or their price.

In addition, some of these panels have a support frame of the absorbent core and facing that is made of wood or aluminum. By nature, these materials have low or no sound absorption properties. In addition, the surface of the frame represents a significant percentage of the total area of the panel.

Therefore, such a support structure decreases relatively significantly the acoustic efficiency of the panel.

3. OBJECTIVES OF THE INVENTION The invention, in at least one embodiment, has the particular objective of overcoming at least some disadvantages of the state of the art.

More precisely, in at least one embodiment of the invention, one objective is to provide a new type of acoustic panel capable, in particular, of reconciling the most stringent requirements in terms of lightness, rigidity and mechanical strength.

Another objective of at least one embodiment of the invention is to provide an acoustic panel that guarantees good efficiency for a relatively low weight and that meets environmental requirements.

Still another objective of at least one embodiment is to provide an acoustic panel having improved acoustic performance, and can be easily integrated in rooms of all sizes (concert hall or living room of a dwelling, for example) .

Yet another objective of at least one embodiment is to provide an acoustic panel for good mechanical strength (whose shape does not evolve or little in time) and an optimal impact resistance. The invention also aims, in at least one embodiment, to provide a manufacturing technique of such a panel that is inexpensive to implement.

4. DISCLOSURE OF THE INVENTION The invention manages to fill all or part of these objectives through an acoustic panel. According to the invention, the panel comprises a core consisting of a honeycomb or honeycomb structure closed only on one side by a wall (or skin, or layer) structure, the core being interposed between two outer layers of material damping, each damping layer being fixed on the core by a layer of glue.

Thus, it is proposed a sandwich type acoustic panel consisting of a honeycomb structure core (called honeycomb) open on one side.

The open face and the closed face of the core are covered by a skin (or layer) of damping material.

Each of these two damping layers is fixed by gluing on one of the faces of the honeycomb core.

Such an acoustic panel may be flat and have a square, rectangular or strip shape.

It has improved qualities of durability, sound absorption and fire resistance.

It has, moreover, a reduced thickness and weight, and is relatively ecological.

It can be placed close to a wall or a ceiling (it is intended in particular to be used as a suspended ceiling element), or it can be used as an interior separation or delimitation panel (thus forming an acoustic screen), in office space, for example.

According to a particular aspect of the invention, the honeycomb structure is made of a material or a combination of materials chosen from cardboard, paper and aramid.

According to a particular aspect of the invention, said structural layer is made of a material chosen from cardboard and paper.

According to a particular aspect of the invention, said outer layers consist of a material chosen from cork, linen, felt, wood wool, cellulose wadding and sheep's wool.

According to a particular aspect of the invention, at least one of said outer layers is covered with a decorative covering fabric.

According to a particular aspect of the invention, said acoustic panel comprises a structuring layer located on the closed side of the honeycomb structure and interposed between the core and the outer layer.

According to a particular aspect of the invention, said structuring layer consists of a material or a combination of materials chosen from cardboard, PVC, nonwoven fabric, flax fiber and melamine resin.

According to a particular aspect of the invention, the thickness of said acoustic panel is less than 40 mm.

According to a particular aspect of the invention, the thickness of said acoustic panel is less than 30 mm.

According to a particular aspect of the invention, the thickness of said acoustic panel is between 20 and 22 mm.

According to a particular aspect of the invention, said acoustic panel is of planar shape.

According to a particular aspect of the invention, said acoustic panel has an arcuate shape.

According to a particular aspect of the invention, said acoustic panel is of polycylindrical shape.

According to a particular aspect of the invention, said acoustic panel is wave-shaped.

According to a particular aspect of the invention, the wave form of said acoustic panel is asymmetrical.

Such an acoustic panel may have a curved, symmetrical or asymmetrical shape, thus combining sound absorption and acoustic diffusion functions.

5. LIST OF FIGURES Other features and advantages of the invention will appear on reading the following description, given by way of indicative and nonlimiting example, and the appended drawings, in which: FIG. 1 is a view schematic section illustrating the interior structure of an acoustic panel according to the invention; - Figure 2 schematically illustrates the absorption principle of the acoustic panel of Figure 1; FIGS. 3a, 3b, 3c and 3d are different views of an acoustic panel according to a first embodiment; FIGS. 4a, 4b, 4c and 4d are different views of an acoustic panel according to a second embodiment; FIGS. 5a and 5b illustrate two examples of assembly of panels identical to that illustrated with reference to FIGS. 4a to 4d; FIG. 6 is a schematic view of an assembly system of two panels according to the invention; - Figures 7a, 7b, 7c and 7d are different views of an acoustic panel according to a third embodiment, and - Figure 8 illustrates the implementation of the panel of Figures 7a to 7d along a wall.

6. DETAILED DESCRIPTION OF THE INVENTION 6.1 Structure of the acoustic panel

Figure 1 is a schematic sectional view of an acoustic panel 1 according to the invention.

The acoustic panel 1, which is here planar and extends in the x-y plane, has a sandwich construction. It consists of a core 11 comprising a honeycomb structure 111 which is formed by at least one acoustically absorbent material.

The honeycomb structure 111 is, for example, made of a paper of aramid fibers, such as that known commercially as "NOMEX" (registered trademark), cardboard, paper or the like, or a combination of these materials.

The honeycomb structure 111 comprises cells arranged transversely (along the z axis).

Classically, these cells are interposed between two continuous (or solid) support layers.

According to the approach of the invention, the acoustic panel 1 comprises a single support layer, or support wall 112, made of cardboard or paper, for example. The side of the cells having no support layer (that is to say the open side of the cells) is intended to be oriented towards the sound source S as shown in Figure 1.

The cells forming the honeycomb structure 111 are, for example, hexagonal section. The thickness of such a structure is, for example, of the order of 10 to 12 mm.

First and second outer layers (or skin) 13A, 13B damping are disposed on either side of the honeycomb structure 111. The thickness of such a damping layer is, for example, the order of 2 to 5 mm. The first and second damping layers 13A, 13B are fixed on either side of the honeycomb structure 11 by gluing, using a glue layer 12A, 12B for example (the adhesive layer present, for example , a thickness of 2 mm).

The outer layers 13A, 13B may be made of an acoustically damping material such as cork, felt, linen, wood wool, cellulose wadding or sheep wool, for example. The combination of some of these materials can also be considered.

At least one of the two outer layers 13A, 13B may be covered with a facing layer, or plating, (not shown). This facing layer, which consists of a fabric or textile covering, for example, allows to present a decorative finish.

Preferably, a facing layer (not shown) covers the outer layer 13A located on the open side of the honeycomb structure 111, that is to say on the visible side of the acoustic panel 1, once the latter is fixed on a wall, for example.

Optionally, an additional structuring layer 14 may be disposed between the support layer 112 and the outer layer 13B. This structuring layer 14 may be formica (registered trademark), PVC, non-woven, or flax fiber.

It should be noted that the acoustic panel according to the invention does not implement a support frame.

The acoustic panel according to the invention has a thickness "e" of less than 40 mm. Preferably, its thickness "e" is less than 30 mm. Preferably, its thickness "e" is between 20 and 22 mm. 6.2 Implementation of the acoustic panel and advantages

FIG. 2 is a block diagram illustrating the implementation of the acoustic panel 1, as described with reference to FIG. 1, in a room and its interaction with a sound coming from a sound source S located on the side of the layer shock absorber 13A (constituting the front panel of the acoustic panel 1). The sound energy incident SI is partly reflected by the acoustic panel 1, the reflected energy S2 returning to the side of the sound source S, and partially absorbed transversely in the acoustic panel 1 (the energy absorbed is referenced S3). Another part of the incident sound energy SI is transmitted through the acoustic panel 1 (the energy transmitted is referenced S4).

The particular structure of the acoustic panel 1 on the one hand, described above and having in particular two damping layers 13A, 13B cork or other, and the absence of one of the two usual structural layers on the honeycomb secondly , allow optimization of the transmission of energy (sound wave) throughout the structure of the acoustic panel 1, resulting in a maximization of the acoustic performance of the entire acoustic panel 1.

In other words, this particular structure of the acoustic panel 1, and particularly the implementation of a honeycomb structure 11, paper and / or Nomex (trademark) for example, optimizes the performance the transverse absorption along the internal thickness of the panel (that is to say, to optimize the energy absorbed S3 along the x and y axes), while creating a multi-membrane effect of the same order in its other dimension (in the thickness of the panel, along the z axis).

These advantages have been observed by the inventors in the areas that are generally the most difficult to process, namely the low-midrange and the low register, ie the frequencies below 400 Hz, and in particular those below 200 Hz. of these aspects can significantly increase the acoustic efficiency of the acoustic panel 1 reported on its surface, compared to a conventional acoustic panel made of soft material (felt type or rock wool type, glass or natural) with a frame in hard material.

The particular multilayer structure of the acoustic panel 1 and its associated absorption and diffusion characteristics allow the acoustic panel 1 to offer better overall acoustic performance by reducing the reverberation time with respect to the areas to be treated in a particularly efficient manner. (listening point).

The acoustic panel 1 according to the invention is homogeneous in nature and reacts linearly, in its entirety, to the stresses of acoustic waves. 6.3 Examples of form of acoustic panel

Figures 3a to 3d illustrate an acoustic panel 1 according to a first embodiment.

The acoustic panel 1 here has a rectangular parallelepiped shape (Figure 3b). The panel may have another shape, such as a square shape.

In this first embodiment, the acoustic panel 1 is flat (that is to say it extends in a single plane), as illustrated in FIGS. 3c (side view) and 3d (seen from above ), which allows easy attachment of the acoustic panel 1 on a wall or a ceiling. As will be seen later, the manufacture of such an acoustic panel 1 is simple and inexpensive.

This particular planar shape combined with the detailed structure previously provide the acoustic panel 1 with superior acoustic performance and lower manufacturing cost than an acoustic panel of the prior art.

An acoustic panel 2 according to a second embodiment is illustrated in Figures 4a to 4d.

The acoustic panel 2 is here of curved shape, and more precisely of polycylindrical shape.

In order to optimize the acoustic efficiency of such an acoustic panel 2, the inventors have determined that, for a width L of reference equal to 650 mm: the optimum height H must be between 1200 and 1300 mm; the optimum radius of curvature (not shown) must be between 454 and 528 mm (and preferably equal to 480 mm); - The depth P, depending on the radius of curvature, must be between 112 and 137 mm.

In this example, the acoustic panel 2 is symmetrical. In a variant, such a panel could be of asymmetrical shape.

In general, a curved acoustic panel, especially of polycylindrical shape, offers a larger exchange area than a flat acoustic panel and, therefore, higher absorption performance.

In general, a polycylindrical panel allows a better acoustic diffusion than a flat panel. The combination of this polycylinder shape and the particular multilayer structure described above offers the acoustic panel 2 superior performance to the panels of the prior art.

Figures 5a and 5b show, in top view, examples of assembly of several acoustic panels 2 according to the second embodiment. These figures respectively illustrate the assembly of two and three acoustic panels 2 mounted head to tail and forming a wave.

Thus, several acoustic panels 2 can be assembled to form a continuous and modular wall depending on the size of a given room. The implementation of such a panel assembly in a room (studio or conference room, for example) can significantly improve the acoustic performance of the latter. The assembly of the acoustic panels 2 is obtained by the implementation of an assembly system comprising magnets 25 which are arranged flushly on the edge of each of the acoustic panels 2.

Figure 6 is a schematic detail view illustrating the implementation of two magnets 25 arranged in the side edges of the acoustic panels 2 and placed opposite one another, the acoustic panels 2 being arranged side by side. Such an arrangement of the magnets 25 makes it possible to obtain a continuous wall and a hermetic connection between two acoustic panels 2 thus assembled.

The acoustic panels 2 can be assembled along a wall (horizontally) or on the height (vertically). In the latter case, magnets 25 are arranged on the upper and lower edges of the acoustic panels 2. Other acoustic panel assembly systems according to the invention can be implemented.

A third embodiment, illustrated in FIGS. 7a to 7d, presents a corrugated acoustic panel. The corrugated acoustic panel, or wave-shaped, can be symmetrical or asymmetrical.

In the example illustrated, the acoustic panel 3 is asymmetrical and has an inverted double curvature. It is arranged vertically along a wall, at a distance from the latter.

The curvature of the acoustic panel 3 is greater on the bottom than on the top of the panel.

For an acoustic panel 3 having a height H 'of reference equal to 1000 mm, the inventors have determined that the depth P' most suitable, measured between points A and B, should be between 59 and 125 mm.

The acoustic panel 3 has a higher diffusion factor than the flat or polycylindrical panels. Generally, the acoustic panels, whatever their shape, are fixed leaving a space of a few centimeters with the wall or the wall on which they are fixed.

This space varies especially with the shape of the panel (flat or not).

In this arrangement, the non-flat panels, as described above, have a better efficiency in the lower spectrum of sound (on low-mid and low). Indeed, their shape makes it possible to trap a quantity or volume of air between the wall (or the wall) and the rear face of the acoustic panel, and thus absorb the sound energy that is there.

FIG. 8 illustrates an exemplary implementation of the acoustic panel 3. The particular form of this acoustic panel 3 allows a sound absorption significantly improved compared to the panels of the prior art.

It should be noted that the gap between the acoustic panel 3 and the wall against which it is arranged is reduced on the top C of the acoustic panel 3 with respect to the bottom D of the acoustic panel 3. This particular configuration makes it possible to optimize the efficiency overall absorption of the acoustic panel 3.

The voices (treble) are generally in height and are therefore absorbed on the upper part of the acoustic panel 3 (located above the point E), while the bass, located closer to the ground, are absorbed by the lower part. acoustic panel 3 (located below point E).

In addition, the curved shapes (non-flat) associated with the particular multilayer structure already mentioned of such an acoustic panel, make it an excellent proximity diffuser. Indeed, the diffusers of the prior art, usually wood, require a greater distance between the sound source and the diffuser, as well as between the diffuser and the area to be treated. A curved acoustic panel in accordance with the invention thus makes it possible to bring the listening point closer together (in other words the position of the listener), which allows the use of such an acoustic panel in small parts, such as the living room of an individual dwelling. 6.4 Acoustic Panel Fabrication

Whatever the shape of the acoustic panel in accordance with the invention, its manufacturing method is substantially identical and comprises: a step of successively placing the various layers constituting the acoustic panel in a mold; a step of applying a depression; and a demolding step of the acoustic panel. The step of placing the layers in the mold respects, of course, a defined order to obtain the particular structure of the acoustic panel described above. In particular, there is provided a step of bonding the outer layers to the honeycomb which is open on one side.

Thus, a first outer layer 13A is disposed at the bottom of the mold, on which a first resin layer 12a is applied. The core 11, comprising the honeycomb structure 111 and the support layer 112, is then affixed to the resin 12A. Once the core 11 is installed in the mold, a second resin layer 12B is applied to which the structuring layer 14 and the second outer layer 13B (optionally) are applied.

The implementation of a depression in the mold is performed by any technique known to those skilled in the art.

Such a manufacturing process is reliable, simple and inexpensive. 6.5 Other aspects and variants

Although described above in its application to the realization in particular of acoustic panels intended to be arranged along a wall or a wall, the invention is obviously susceptible of applications in any other field where it turns out it is necessary or desirable to use a sandwich panel type structure combining lightness, high mechanical strength and optimized acoustic properties.

In addition, the forms of the acoustic panel presented above are described by way of example. It is obvious that other geometric shapes can be envisaged and that many variations are possible.

One can also consider implementing a plurality of holes on the face facing the sound source of an acoustic panel according to the invention (and in particular on a flat acoustic panel according to the first embodiment).

The implementation of these holes allows a better penetration of sound energy inside the honeycomb structure of the acoustic panel and thus improves the absorption efficiency of such an acoustic panel.

Furthermore, the fixing of the acoustic panels on a support (a wall or a ceiling, for example) is obtained by the implementation of inserts (not shown) on the rear face of the acoustic panels. These inserts are configured not to degrade the acoustic performance of the acoustic panel, by preventing the maximum, when using the acoustic panel, the transmission of any form of vibration of the structure to the insert.

The acoustic panel according to the invention can be placed on the ground or mounted on foot (s).

Claims (15)

1. Acoustic panel (1) characterized in that it comprises a core (11) constituted by a honeycomb structure (111) closed only on one side by a structural layer (112), the core (11) ) being interposed between two outer layers (13A, 13B) of damping material, each damping layer (13A, 13B) being fixed on the core (11) by an adhesive layer (12A, 12B). Acoustic panel (1) according to claim 1, characterized in that said honeycomb structure (111) consists of a material or a combination of materials chosen from cardboard, paper and aramid. 3. acoustic panel (1) according to claim 1 or 2, characterized in that said structural layer (112) is made of a material selected from cardboard and paper. 4. acoustic panel (1) according to one of claims 1 to 3, characterized in that said outer layers (13A, 13B) are made of a material selected from cork, linen, felt, wood wool , cellulose wadding and sheep's wool. 5. acoustic panel (1) according to one of claims 1 to 4, characterized in that at least one of said outer layers (13A, 13B) is covered with a decorative coating fabric. 6. acoustic panel (1) according to one of claims 1 to 5, characterized in that it comprises a structuring layer (14) located on the closed side of the honeycomb structure (111) and interposed between the core (11) and the outer layer (13B). 7. Acoustic panel (1) according to claim 6, characterized in that said structuring layer (14) is made of a material or a combination of materials selected (s) from cardboard, PVC, nonwoven, flax fiber and melamine resin. 8. acoustic panel (1) according to one of claims 1 to 7, characterized in that the thickness of said acoustic panel (1) is less than 40 mm. 9. acoustic panel (1) according to claim 8, characterized in that the thickness of said acoustic panel (1) is less than 30 mm. 10. acoustic panel (1) according to claim 9, characterized in that the thickness of said acoustic panel (1) is between 20 and 22 mm. 11. Acoustic panel (1) according to one of claims 1 to 10, characterized in that said acoustic panel (1) is of planar shape. 12. acoustic panel (1) according to one of claims 1 to 10, characterized in that said acoustic panel (1) has an arcuate shape. 13. acoustic panel (1) according to one of claims 1 to 10, characterized in that said acoustic panel (1) is of polycylindrical form. 14. acoustic panel (1) according to one of claims 1 to 10, characterized in that said acoustic panel (1) is wave-shaped. 15. Acoustic panel (1) according to claim 14, characterized in that the wave shape of said acoustic panel (1) is asymmetrical.