RU2265251C2 - Multilayer noise-absorbing panel - Google Patents

Abstract

FIELD: noise-absorbing panels.

SUBSTANCE: multilayer noise-absorbing panel has a layer of porous, gas-penetrable, open-cell foam noise-absorbing material, which is protected by thin layer of sound-transparent gas-impenetrable film-like material. Structure of porous layer of sound-absorbing material, for given space direction of structure volume, is formed by a set of directionally grouped in a certain way, at least two types of families of alternating pores of different geometric dimensions, forming an appropriate specifically given non-homogenous rigid skeleton frame structure. Groups of families of lesser pore groups form volumetric zones of structure with higher rigidity in comparison with volumetric, softer zones of structure, formed by families of larger pore groups of porous layer. Face surface of porous sound-absorbing material layer is in thermal-adhesive and gapless way is connected to thin protective layer of gas-impenetrable sound-transparent film-like material with forming of resulting, having appropriate non-homogeneousness of rigidity, density, resistance to blowing-through sound-absorbing structure in form of alternating volumetric zones and local surface projections and recesses of waving-wrinkled shape.

EFFECT: higher efficiency, broader functional capabilities.

9 dwg

Description

The invention relates to noise-absorbing panels, in particular, below is considered a flat, combined, noise-absorbing panel, mainly designed to absorb industrial (industrial) and traffic noise, and can be widely used in the automotive industry to reduce the noise produced by cars.

Porous sound-absorbing materials - fibrous and foamed - are known and widely used in the technique of damping noise energy. Fibrous materials are represented by fibers of organic or inorganic origin, and foamed materials are usually open-cell polymers (polyurethane foams, polyethylene, polyvinyl chloride, etc.). An effective sound-absorbing material should not only absorb sound energy, but also be lightweight, cheap to manufacture, resistant to external influences, safe to operate and recyclable. In many cases of the use of porous sound-absorbing panels, the outer surface layer should not contain open pores that contribute to the accumulation of dust in its structure, absorption (absorption) of harmful substances (operating rooms, kitchens, engine compartments, cabins and passenger compartments of vehicles, etc.). In these cases, the sound-absorbing panel is laminated with a protective lining of the outer surface of the porous structure (skeleton) with a thin sound-transparent film (foil) such as aluminized, polyester, polyurethane, vinyl, etc. Of particular relevance is the use of these foamed sound-absorbing materials with an external lining with a sound-transparent film after it has been proved, for example, that such a porous-fibrous material as asbestos is a carcinogen (a causative agent of cancer). Similar problems arise with the use of other porous fibrous materials such as fiberglass, basalt fiber, etc., due to the possible small particles of these materials in the form of dust or particles of fibers entering the air environment. In this sense, the use of foamed-porous polymeric materials in the form of monolithic sheet structures lined with a protective thin sound-transparent film is favorable from the point of view of improving the environment.

Porous open-cell foams, such as polyurethane foams, can be effective materials for absorbing sound energy. Their effectiveness mainly depends on the intensity of the process of dispersion of sound energy associated with the movement of air through narrow systems of asymmetric and branched channels of a porous structure. The internal deformation and damping of the porous skeleton due to the impact of incident sound waves contributes to the additional dissipation of sound energy. Foamed porous sound-absorbing materials can be isotropic structures due to the peculiarities of the technology of fluid processes during foaming and solidification randomly distributed throughout the pore structure of various geometric ratios. The viscoelastic characteristics of such a porous structure differ in the direction of thickness in a plane perpendicular to this direction, i.e. the properties are mainly transversely isotropic. Such a porous foam structure can be represented as a two-component continuous medium consisting of a foam skeleton and air. The air moves relative to the frame and the frame is deformed. Both of these components (air and skeleton) are interconnected by frictional forces, as a result of which the conversion of mechanical work (deformation, friction) into heat is possible.

Known methods and devices for producing highly effective porous foam materials based on polymers by imparting the porous structure of materials anisotropic properties. The anisotropy property of the structure of foamed materials can be ensured both directly due to the formation (communication) of the material structure of various substantially different physical characteristics in various coordinate directions, such as elastic modulus (Young's modulus), shear modulus, Poisson's number, loss coefficient, and the introduction into the skeleton of the porous structure of various foreign structural elements that form anisotropic properties in specified directions and / or impart, for example, the structure of opogloschayuschey panel predetermined geometric shape.

Such methods and devices are known, in particular, from publications:

/1/. T. Alts, Unikeller "The significantanse of anisotrony for the acoustical effectiveness of visco - elastic foams", Unikeller Conference - 89, Zurich, 1989, p.8 / 1 ... 8/23;

/ 2 /. DE No. 4113628 A1, IPC G 10 K 11/16, publ. 1992;

/ 3 /. FR No. 2667430 A3, IPC G 10 K 11/16, publ. 1992;

/4/. DE No. 4332856 A1, IPC G 10 K 11/16, publ. 1995;

/5/. DE No. 3219339 C1, IPC G 10 K 11/16, publ. 1983;

/ 6 /. EP No. 0643203 B1, IPC F 01 N 7/10, publ. 1995;

/ 7 /. EP No. 0 509 603 A1, IPC G 10 K 11/16, publ. 1992;

/8/. RU No. 2106021 C1, IPC G 10 K 11/16, publ. 1998;

/9/. US No. 5554830, IPC E 04 In 1/81, publ. 1996;

/10/. PCT / WO No. 91/09728, IPC 32 V 11/04, publ. 1991;

/eleven/. PCT / WO No. 00/27671, IPC B 60 R 13/02, publ. 2000;

/12/. RU No. 27026 U1, IPC B 60 R 13/08, publ. 2003;

/thirteen/. USSR author's certificate No. 348755, F 01 N 1/04, 1972.

In particular, in / 1 / the problems of the production of highly efficient multilayer soundproofing materials containing porous fibrous and / or foamed sound-absorbing layers in combination with a dense weight sound-insulating layer are considered. Due to the optimal selection of the stiffness characteristics of the components of the layered soundproofing system, imparting anisotropy to the foamed layer by a random distribution of pores of various overall dimensions, combined with a dense sound-reflecting wave, a soundproofing soundproof layer, the possibilities of changing the “soundproofing” parameter of layered soundproofing structural packages in the rear are illustrated ranges.

B / 2 / claims the design of a sound-absorbing material with anisotropic physical properties by imparting a lower value of the elastic modulus "E" in a specific spatial direction of the porous structure of the material with respect to other directions of the three-dimensional volume of the porous structure of the material, providing better coordination of wave resistance of the air near the interface between the surface structure of the porous material with wave resistance inside the porous structure. The value of the module "E" in a given spatial direction (each of 3) is unchanged.

B / 3 / claims a multilayer soundproofing panel containing a combination of porous layers of fibrous and foam materials, a supporting panel, a heavy bituminous soundproofing layer, a protective layer of rigid material, specially formed large-sized air cavities that together provide the specified soundproofing ability of the soundproofing panel when used as a specific one a structural element of soundproof casings, screens, cladding, etc.

B / 4 / claims a multilayer sound-absorbing flat element with a perforated carrier plate, providing anisotropy of the sound-absorbing properties of the porous layer over the thickness of the element and forming a given sound absorption by choosing a specific perforation of the carrier plate. The outer protective surface of the element is made of a soundproof material with weak reflection of the sound waves incident on the element, which ensures the process of effective sound absorption by the structure of the flat element.

B / 5 / claims a flat sound-absorbing panel made of foamed isotropic material, the outer (receiving for incident sound waves) surface of which is made knobby to improve the sound absorption effect, while the vertices of these knolls of an uneven profile of the foam are covered with a thin protective foil. Some improvement in sound absorption, due to the better coordination of the wave impedances of the surrounding air and the porous layer in the area of their separation (vertices covered with foil), created by the geometry of the convex tubercles and concave depressions of the surface porous layer, is negatively combined with the low strength and performance properties of such a panel (primarily - ease of damage to areas of thin foil that are not backed to the tops of the hillocks).

B / 6 / claims a porous noise-insulating heat shield mounted in areas of the exhaust pipes of an internal combustion engine (ICE), in which an external protective structure made of a soundproof metal mesh is used to ensure strength characteristics in a vehicle’s operating conditions.

B / 7 / claims a multilayer design of sound-absorbing material, the basis of which is a porous structure with a Young's modulus not exceeding 10 ⁵ n / m ² to ensure a high sound absorption coefficient in the low-frequency region of the sound spectrum. The disadvantages of the known device are the limited frequency range of effective sound absorption, the pronounced flat geometry of the sound-absorbing panel with insufficiently high conditions for matching the wave impedances of the air and the porous layer in the area of their separation, the absence of a thin sound-transparent protective film lining the front surface of the porous layer of material, low strength and performance due to low Young's modulus material.

B / 8, 9, 10 and 11 / declare multilayer sound insulating materials containing a combination of porous sound absorbing, dense weight sound insulating and specific aesthetic layers, operating on the principle of "oscillating mass - elastic spring", providing a specified increase in sound insulating properties. The composition of this combination can also include perforated layers of dense material or closed air cavities can be formed for directional changes in local densities and stiffnesses of the structure, and as a result, directional changes in sound insulation in a given frequency range.

B / 12 / claims a sound-absorbing cladding in which perforation discharge holes are made on mounted curved surfaces of the panels, eliminating deformation stresses and seals of porous structures in these zones, resulting in loss of sound absorption in these zones. The disadvantages of such cladding designs are the partial loss of volume of the porous sound-absorbing structure in the areas of perforation holes and the high probability of damage to the thin protective foil of the cladding in the areas of holes in the porous layer with subsequent accumulation of moisture, oil, dust, etc.

In the design of the device described in / 13 /, sound-absorbing effects similar to the device considered in / 5 / are realized. The disadvantages are poor protection of the porous layer by a perforated screen from dusting, moisture, etc. and, in connection with this, the occurrence of their limited application in terms of layout options in cramped engine compartments and cabs of vehicles.

From the description of the patent of Russia No. 2188772, IPC 7 B 60 R 13/08, publ. 09/10/2002, BI No. 25, a multilayer noise-reducing gasket for a vehicle body panel, such as a passenger car, is known, containing at least a layer of porous sound-absorbing material, on the outside of which a thin protective layer of film material is adhesively mounted, and on the mounting side - mounting adhesive a layer on which an easily removable layer of protective material is placed, an adhesion layer between the outer side of the porous sound-absorbing material and the counter surface of the protective film layer Container material formed as a thin line pattern composed of a plurality of regular geometric shapes. The lines of the pattern can intersect with each other, forming many elementary closed geometric shapes, or the lines of the pattern can be made mutually parallel or equidistant. At the same time, the lines of the pattern can have a continuous path or be made in the form of discontinuous lines. Thus, without violating the integrity and tightness of the outer surface of the panel as a whole, it is possible to provide a weak negative effect of the adhesive layer on the sound-absorbing ability of the gasket in the area of the outer surface of the PPU-conjugated film layer, thereby preserving the named outer surface of the PPU relatively free and, accordingly, malleable and porous for the passage and absorption of sound that is not covered by a continuous adhesive layer (not fused over the entire surface of the interface with a fire or thermal adhesive iem) having a limited free air contact with the protective layer of the film (foil) material, which greatly improves the dissipation of energy of sound waves, i.e. increases the effect of sound absorption. As a result, higher reliability and durability of the noise-absorbing gasket are provided, its aesthetic qualities are improved. At the same time, the formed flat surface of the outer facing layer, as a result of the adhesive bond of the protective film with a uniformly uniform, equally rigid, in the specified directions of the structure, isotropic porous layer of the polyurethane foam sheet, as a result, in some cases, does not provide the required sound absorption capacity as in absolute the value of the sound absorption coefficient, and the width of the effective frequency range of sound absorption. The use of "very soft foam" with a low Young's modulus "E" is often unrealistic due to the low strength and performance characteristics of the gasket structure.

As a prototype, a flat element (sound-absorbing panel) for sound absorption, described in the patent of Germany (DE) No.PS 3219339, IPC G 10 K 11/16, publ. 02.03.83, Bulletin No. 5, which contains an elastic porous layer of foam and a protective surface layer in the form of a foil. The element is characterized in that the foam layer at least on one side has a tuberous profiled surface, and the foil of artificial sound-transparent material, in the form of a thin-walled plate, is fixed only on the tops of the tubercles of the uneven external profile of the foam. However, as in the analogue described above, the formation of voids (air cavities) between the thin foil and the surface of the porous foam reduces the operational reliability of the panel due to the possible violation of the integrity of the thin foil in the zones of these voids (for example, as a result of mechanical damage). As a result of this, various external factors, such as dust, moisture, engine oil, fuel, etc. can accumulate in the formed cavities under the film and destructively affect the porous structure of the sound-absorbing material, while reducing its sound-absorbing qualities.

Both in the prototype and in the above examples reflecting the prior art, both isotropic materials with identical size and physical characteristics of pores are described, as well as anisotropic porous foam sound-absorbing structures, the change of the stiffness and sound-absorbing characteristics of which is carried out, first of all, for due to the random nature of the change in geometric dimensions, randomly distributed pores of the foam layer of the material throughout the volume of the structure, given sizes and number of pores, open sizes anal, oral reporting neighboring pores distributed randomly throughout the volume of the structure. Thus, the sound-absorbing structure as a whole has approximately the same stiffness characteristics, blowing resistance and the obtained sound-absorbing characteristics in a given specific spatial direction of the porous sound-absorbing structure.

The essence of the invention lies in the fact that in the known multilayer sound-absorbing panel containing a layer of porous, gas-permeable, open-celled foamed sound-absorbing material, which is protected by a thin layer of sound-transparent gas-tight film material, the structure of the layer of porous foamed sound-absorbing material in a predetermined spatial direction of the volume of the structure is formed by a plurality of directionally directed direction of the structure volume. grouped in a certain way, at least two types of families alternating, from varying in their geometrical sizes of pores, forming a correspondingly predetermined non-uniform stiffness skeletal structure, while families of smaller pore groups form volume zones of the structure with higher stiffness compared to volume, softer zones of the structure formed by families of larger groups of pores porous layer, the front surface of the porous foamed sound-absorbing layer of the material is thermally adhesive and gaplessly connected to a thin protective layer of gas-tight o sound-transparent film material, with the formation, as a result, of a corresponding inhomogeneous in stiffness, density, blowing resistance of the sound-absorbing structure in the form of alternating volumetric zones formed and local surface protrusions and depressions of a wavy-wrinkled appearance. In fact, the reinforced structure of the composite sound-absorbing material of a given spatial orientation is realized, in which the families of “small” pores connected to the film layer serve as the reinforcing system — the matrix, and the family of “large” pores - the filler.

In addition, there can be more than two such families, while the sizes of the pore groups of these families should differ from the pore sizes of the two families described above.

The mounting side of the porous layer of foamed material contains one of the means known from the prior art for securing the panel on the defatted surface of the corresponding vehicle body panel or other object of technology, in which the problem of noise reduction is solved, for example, it may be a sticky adhesive layer or a layer of thermally activated substance, etc.

Thus, in contrast to the well-known principles of anisotropy - as a relatively weakly controlled process of giving a porous sound-absorbing structure to a panel with high sound-absorbing properties due to the random distribution of pores of a given size throughout the volume of the structure, we propose a technological principle for defining ordered anisotropy in a porous foam material - directional, oriented in a certain grouping into given pore families of approximately the same geometric dimensions, to the right data to enhance the sound absorption effects, providing the specified strength and durability characteristics of the panel by communicating to the panel structure both the functions of the additional supporting skeleton (“matrix” with local zones of higher rigidity) and the introduction of dynamically malleable “soft” filler zones filling the skeleton "hard" spaces. At the same time, the properties of the panel as a whole are controlled both by choosing the sizes of the pore groups and by grouping them into homogeneous families in predetermined areas of the panel structure space with the subsequent formation of a predetermined tuberous-wrinkled surface layer during thermo-adhesive stitching of a protective soundproof gas-tight film with a porous surface layer of open-cell foam.

The invention is illustrated in the drawings, where:

- on figa shows the inventive sound-absorbing panel (state "in stock");

- Fig.2b shows the claimed conditionally layered panel in its pre-installation condition;

- figure 2 shows a family of pores of one of the groups that make up the sound-absorbing gas-permeable structure of the panel; increased;

- figure 3 and 4 show possible options for the construction of multilayer sound-absorbing panels, respectively, with a wavy and tuberous front surface, the structure of which consists of two groups, including families of small and large pores (cells);

- on figa, 6a, 7a shows possible options for the design of the inventive multilayer sound-absorbing panels, the porous structures of which consist of three groups, including families of conditionally "small" in size, "medium" and "large" pores;

- on figb, 6b, 7b shows a cross-section along aa the above panels.

Obviously, real structural structures constructed according to these structural and technological principles, in practice, may contain a number of unprincipled deviations from strictly idealized ones (as shown in the graphic illustrations above). First of all, this applies both to the appearance of the formation of the facial structure with deviations from its forms of combinations of regular geometric shapes of absolutely identical size, and the formation of the structure of foam material in a given area from close-in (but not absolutely identical) pores, etc.

- Figures 8 and 9 show the results of an experimental evaluation of the sound absorption efficiency of the claimed material of type AA 25 SMT (polyurethane foam layer thickness 25 mm) and AAD 12.5 SMT (polyurethane foam layer thickness 12.5 mm) in comparison with similar materials manufactured by Perstorp - Antiphon, Sweden, type LA 25 SE (polyurethane foam layer thickness 25 mm) and LDA 12.5 SE (polyurethane foam layer thickness 12.5 mm), which are considered to be among the most effective in the world market of sound-absorbing materials.

The considered multilayer sound-absorbing panel comprises a layer 1 of porous, gas-permeable foamed sound-absorbing material, which is protected by a thin layer 2 of sound-transparent gas-tight film material. On the mounting side of the porous layer 1 there is a layer of thermo-adhesive substance 3 (although any other of the well-known from the prior art means of fastening similar panels to a structural element of a vehicle body or other object of technology in which the problem of noise reduction is solved) can be used. The structure of the porous sound-absorbing layer 1 of the foam material is formed by a plurality of alternating families grouped in a certain way, different in their geometrical pore sizes, forming a rigid skeletal structure non-uniform in surface and volume. Groups 4 of the smallest pores form zones of structure with higher stiffness compared with structure zones formed by groups 5 of the largest pores of the porous layer 1. The front surface 6 of the porous sound-absorbing layer 1 of the material is thermally adhesive 7 and gaplessly connected to the thin protective layer 2 of the gas-tight sound-transparent film material and forms together with it an inhomogeneous sound-absorbing structure in the form of locally distributed surface protrusions and troughs of a wavy-wrinkled appearance. In addition, in the space of the volume of the porous structure of the foam material located between groups 4 and 5 formed by families of “small” pores and “large” pores, groups of 8 families of pores can be located, the sizes of which are in an intermediate size range limited by the sizes of these “small” ones "and" large "pores constituting additional families in the respective groups.

The layer of thermo-adhesive substance 3 on the mounting side of the porous layer 1 in the pre-mounting state is covered with a protective layer 9 (this can be thick waxed paper, lavsan film, etc.), which is easy before mounting the panel, for example on the corresponding surface of the car body structure (not shown) of the car deleted.

The specific composition of the panel structure depends on the degree of sufficient effectiveness of the functions it performs. In general, the panel may take the form of a multilayer sandwich, including, in particular, a thin soundproof gas-tight layer 2 (polyester, vinyl, urethane, polyethylene film, thin aluminum foil, etc.), a layer of thermally activated substance 7 (hot forming of the film 2 with filamentary fibers, with the formation of a knobby or wrinkled front surface as a result of completion of this technological process 6), a porous (foamed open-cell) layer 1 of sound-absorbing material, the quality of which is m Open cell polyurethane foam (PUF), for example, can be used.

Before directly mounting the panel, for example, on the corresponding body panel, the protective paper layer 9 is removed and, by applying the panel with an adhesive layer 3 on the degreased surface of the panel, fix it on the steel body panel in the right place (by pressing manually or using a magnetic roller).

Families of pores 5 with maximum overall dimensions in this volume zone of the porous structure of the material report conditions of increased deformation due to the realized lower stiffness of the walls and volume of pores in this volume zone and, accordingly, their greater flexibility as a result of dynamic deformation. As a result of the implementation of these dynamic processes, it is possible to efficiently convert the energy of sound waves incident on the porous structure into the corresponding mechanical work for directed deformation of the porous skeleton, as well as changing the shapes of air volumes in the pores, air flowing through the communicating channels of the cells (pores) and, as a result, further converting it into dissipated thermal energy, which, thus, provides an effective process of suppressing sound energy (i.e., reducing noise levels during tion of a specific technical problem).

The smaller family of pores 4, having higher stiffness characteristics, combined with a thin film layer, forming a reinforcement matrix with a given spatial orientation, not only provides the foamed open-cell sound-absorbing structure of the material with the required bearing capacity and higher strength characteristics required by the operating conditions of the technical object (for example, a vehicle), but also extends the frequency range of effective sound absorption in the high frequency region. On the other hand, the alternation of families of pores 4 and 5 of different overall dimensions allows, if necessary, the formation of alternating zones of variable stiffness in a given coordinate direction of a three-dimensional porous three-dimensional structure, for example, in the transverse plane of a section of sheet material. Ultimately, such a porous structure, being subsequently “crosslinked” by its external (perceiving incident waves) surface layer by means of a thermo-adhesive layer 7 of a binder with a thin elastic sound-transparent protective film 2, as a result of completion of the process of thermo-adhesion of the stitched layers, forms a wavy tuberous or wrinkled surface sheet layered sound-absorbing material. A tuberous or wrinkled surface of the material is formed by pairing a thin film and the opposing surface of the porous layer as a result of various deformations in the process of thermal adhesion of alternating “soft” and “harder” portions of the porous layer of foam material with an elastic layer of a thin soundproof protective film 2, also contributes to a more smooth coordination wave resistance of media in the zone of separation of the porous skeleton of the material with the air and directly in the volume of the porous structure of the material (in avnenii with the known embodiment, when such a sound receptive surface of the porous material is strictly flat).

Thus, the anisotropy of the stiffness and damping characteristics of the skeleton of the panel structure formed in a certain way is ensured by the arrangement of spheroidal hollow cells of various sizes (radii) of open-celled foam material arranged in groups (families), for example, polyurethane foam and a flexible skeleton of a porous structure, the dynamic stiffness and damping of which changes accordingly image with purposefully specified grouping and arrangement of individual pore groups. In this case, the “larger” cell sizes of the hollow pores locally provide a softer volume zone of the skeleton structure of the open-cell polyurethane foam, and, correspondingly, the “smaller” ones provide the locally more rigid zone of the skeleton structure of the polyurethane foam, unlike the version, for example, using open-cell polyurethane foam with the same cell sizes, reporting essentially isotropic stiffness characteristics in all three coordinate directions randomly located in volume pores of various geometric sizes.

Thus, the rational constructive and technological technique combines the conflicting requirements of ensuring high sound-absorbing properties of the porous structure of the material, eliminating the contamination of the porous structure, while ensuring sufficient rigidity and strength of the sheet panel as a whole. This is achieved, first of all, by communicating the porous structure of ordered inhomogeneous anisotropic stiffness characteristics in specified cross-sectional areas of the skeleton, the formation of alternating zones with lower and higher dynamic stiffness, the sufficient operational strength and durability of the panel is ensured by the increased bearing capacity of the matrix skeleton formed by more rigid alternating zones of the porous layer associated with a protective sound-transparent film (foil), thermo-adhesive " stitched "with an oncoming surface layer of the porous structure, with the formation of the front tuberous or wrinkled surface structure of the sound-absorbing panel.

Figures 8 and 9 show the results of an experimental evaluation of the sound absorption efficiency of the claimed material of type AA 25 SMT (polyurethane foam layer thickness 25 mm) and AAD 12.5 SMT (polyurethane foam layer thickness 12.5 mm) in comparison with similar materials manufactured by Perstorp- Antiphon, Sweden, type LA 25 SE (polyurethane foam layer thickness 25 mm) and LDA 12.5 SE (polyurethane foam layer thickness 12.5 mm), which are considered to be among the most effective in the world market of sound-absorbing materials, illustrate the achieved significant positive technical effect by Sound Absorption Compared Materials are identical in structural composition, including the use of a protective polyester aluminized film, crosslinked with an open-cell polyurethane foam layer, and have the same thickness.The tests were carried out on samples of materials in the form of flat sheets with an area of 1 m ² (1 m × 1 m) when placed in a bench research installation "Cabin Alpha", which is a small reverberation chamber in which a diffuse sound field is generated. The essence of the method used to evaluate sound-absorbing properties was to determine the reverberation coefficient of sound absorption of a large-sized sample of material from the attenuation rate of sound in the space of the measuring chamber of the Cab Alpha test setup. As can be seen from the presented test results, the claimed design of sound-absorbing panels made of materials AA 25 SMT and AAD 12.5 SMT have a significantly higher (in some frequency areas - over 20%) value of the reverberation sound absorption coefficient. These experimental results clearly confirm the novelty and effectiveness of the claimed structure of the sound-absorbing panel.

Claims (1)

A multilayer sound-absorbing panel, in particular containing a layer of porous, gas-permeable, open-cell sound-absorbing material, which is protected by a thin layer of sound-transparent gas-tight film material, characterized in that the structure of the porous layer of sound-absorbing material in a given spatial direction of the volume of the structure is formed by a plurality of directionally grouped in a certain way, at least two types of alternating families, differing in their geometric pore sizes that form a correspondingly defined non-uniform stiffness skeletal structure, the grouped families of smaller pore groups form volumetric zones of the structure with higher stiffness compared to the volumetric, “softer” structure zones formed by the families of grouped larger pore groups of the porous layer the surface of the porous sound-absorbing layer of the material is thermally adhesive and gaplessly connected to a thin protective layer of a gas-tight sound-transparent film material with the formation of the resultant corresponding inhomogeneous in rigidity, density, resistance to blowing sound-absorbing structure in the form of alternating volumetric zones formed and local surface protrusions and troughs of a wavy-wrinkled appearance.

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