EP2394265B1 - Acoustic absorber, acoustic transducer, and method for producing an acoustic absorber or an acoustic transducer - Google Patents
Acoustic absorber, acoustic transducer, and method for producing an acoustic absorber or an acoustic transducer Download PDFInfo
- Publication number
- EP2394265B1 EP2394265B1 EP10709986.3A EP10709986A EP2394265B1 EP 2394265 B1 EP2394265 B1 EP 2394265B1 EP 10709986 A EP10709986 A EP 10709986A EP 2394265 B1 EP2394265 B1 EP 2394265B1
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- EP
- European Patent Office
- Prior art keywords
- absorption layer
- absorber
- layer
- absorption
- acoustic absorber
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R7/00—Diaphragms for electromechanical transducers; Cones
- H04R7/26—Damping by means acting directly on free portion of diaphragm or cone
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/162—Selection of materials
- G10K11/168—Plural layers of different materials, e.g. sandwiches
Definitions
- the invention relates to an acoustic absorber according to the preamble of claim 1 and to a method for producing an acoustic absorber according to the preamble of claim 13.
- the energy of the sound waves penetrating into the open-pore porous material is at least partially converted into heat energy in the material, in particular by the fact that the kinetic energy of air molecules connected to the sound wave is converted into heat by friction of the air molecules at the material enclosing the cavities.
- This absorption mechanism results in shorter wavelengths of sound, i. higher frequency, are absorbed more than low frequencies.
- the US Pat. No. 6,145,617 A a sound-insulating arrangement with a porous damping layer and a porous porous and rigid reinforcing layer.
- prior art acoustic transducers e.g. in the form of area loudspeakers, but often having a strong non-linear frequency characteristic.
- the problem underlying the invention is to provide an acoustic absorber for the absorption of sound waves, which can be produced in the simplest possible way and still allows sound absorption over a wider frequency range.
- the invention is further based on the problem of specifying a method for producing such an acoustic absorber.
- an acoustic absorber for sound damping which has an absorbent layer formed from an open porous material, wherein the porous porous material is so elastic that the absorption layer is excited upon impact of sound waves to bending vibrations with natural frequencies of the absorption layer (1) and the absorber due to the inflow of air into the porous porous material of the absorption layer, sound waves of a first frequency range and by the excitation of bending vibrations of the absorption layer can absorb sound waves of a second frequency range comprising lower frequencies than the first frequency range, the porous porous material consisting of multiple nonwoven layers and for bonding the nonwoven layers and / or the fibers of the nonwoven layers has a binder in the form of latex and / or a thermally activatable binder.
- the first and the second frequency range partially overlap.
- the properties of the absorption layer can be selected such that the two frequency ranges overlap in a predetermined overlap frequency range in order to produce increased absorption in this region.
- the absorption layer thus combines two absorption mechanisms together, namely the typical absorption of an open porous material at higher frequencies with absorption via the excitation of bending vibrations at lower frequencies.
- the absorber is able to dampen sound waves over a wide frequency range, ie it is not necessary, in addition to the porous porous
- Absorption layer to provide other means for damping the sound waves at lower frequencies.
- two different absorption mechanisms are thus to some extent connected in parallel.
- Porous materials include all porous and fibrous materials such as textiles, nonwoven, carpet, foam, mineral wool, cotton, special acoustic plasters, expanded glass granules, and so-called porous materials that absorb sound energy by frictionally converting vibrations of the air particles into heat energy.
- Thin porous porous absorption layers such as textiles preferably absorb in the high-frequency range.
- Thin porous porous absorption layers preferably absorb in the high-frequency range.
- several porous porous absorption layers with increasing flow resistance arranged one behind the other.
- the layer with the lowest flow resistance of the sound source is turned. This ensures in particular that the absorption layers, which are arranged facing away from the sound source, do not lose their effectiveness through the cover by the other absorption layers.
- the ratio of the flexural rigidity (or mass, thickness and / or dimensions) to the flow resistance of the absorbent layer may be selected depending on the intended application of the acoustic absorber, e.g. To avoid a drone in smaller rooms or a relatively lower frequencies too strong absorption of high frequencies.
- the absorption properties of the absorber according to the invention in the lower frequency range, the formation of a "flutter echo", e.g. be counteracted when lining rooms with the absorber.
- the inventive acoustic absorber can replace a combination of different types of absorbers, thereby reducing costs, weight and assembly time, for example.
- the acoustic absorber according to the invention can of course certainly be combined with conventional absorber types, for example the absorption layer of the acoustic absorber according to the invention can be used as the end face (muzzle surface) of a Helmholtz resonator instead of the insulating material conventionally used as end face.
- the absorption layer has such a flexural rigidity that the natural frequency of the absorption layer with respect to flexural vibrations is below 600 Hz, in particular below 300 Hz or in particular of 200 Hz.
- the absorption layer may have a similar flexural rigidity. However, this is not mandatory, but the bending stiffness with respect to different load directions can of course also be different.
- the absorbent layer may have increased flexural elasticity, ductility and / or crush resistance, particularly in comparison with conventional absorbers (e.g., having a mineral fiber or open cell foam).
- the porous-porous material of the absorbent layer is more ductile than glass or rock wool, i. in particular, that the open-pore porous material of the absorption layer has a greater breaking strength than these materials.
- the maximum permissible tensile force of the porous porous material of the absorbent layer is at least 10 percent greater than that of glass.
- the absorption layer may have a basis weight in the range of 30 g / m 2 to 20 kg / m 2 , in particular between 1 to 5 kg or between 1 to 3 kg.
- the basis weight does not have to be constant over the absorption layer, but it may also be location-dependent, ie the basis weight may vary, for example, in the thickness direction of the absorption layer and / or in a direction perpendicular to the thickness direction.
- the bulk density of the porous porous material of the absorption layer may be generally location-dependent, ie vary across the absorption layer and not only in the thickness direction.
- the bulk density of the porous open-pore material increases in the thickness direction of the absorption layer (progressive densification) or increases or decreases from a center of the absorption layer to its (perpendicular to the thickness direction) surfaces.
- the mass density of the absorption layer may also increase in the thickness direction relative to a first cross section of the absorption layer and decrease with respect to a second cross section which is at a distance from the first cross section. This can also be done alternately, i. When viewed along the length or the width of the absorption layer, the bulk density of the absorption layer alternately increases and decreases in the thickness direction.
- the bulk density can also extend in the manner of a honeycomb structure to increase the stability of the absorption layer.
- the "absorption layer" of the absorber is understood in particular to be a planar structure which extends along a main extension plane and whose dimension perpendicular to the main extension plane is small in relation to the dimensions parallel to the main extension plane.
- the absorption layer is formed in the form of a plate, wherein the acoustic absorber, for example, consists at least substantially only of this plate.
- the absorption layer is e.g. at least approximately rectangular, e.g. with a length between 30 and 150 cm and a width between 30 and 100 cm (with for example a thickness between 5 and 20 mm).
- the invention is of course not limited to a particular form of absorption layer, but the shape and dimensions of the absorption layer can in principle be chosen arbitrarily depending on the intended application of the acoustic absorber.
- the absorption layer does not necessarily have to be flat, but may also extend at least in sections in a curved manner, so that it may be e.g. with respect to a concave or convex surface. Furthermore, it is possible to make an adjustment of the natural frequencies of the absorption layer or a scattering or bundling of the incident sound waves via the strength of the curvature of the absorption layer.
- the absorption layer has, for example, a thickness in the range from 0.1 mm to 100 mm, in particular in the range between 3 mm and 20 mm, it being understood that it is not mandatory for the absorption layer to have a constant thickness. It is also conceivable that the thickness is location-dependent, ie it can be in a direction parallel to a main plane along which vary the absorption layer, for example, to increase the sound absorption by increasing the surface of the absorption layer and / or to produce a diffuse sound-reflecting surface (eg by a wave-shaped configuration of at least one surface of the absorption layer).
- the absorption layer may be flat (i.e., at least substantially non-curved), but not continuous, but e.g. has a (in particular rectangular or circular) opening.
- the absorption layer may be designed such that it circulates around a (central) opening in the manner of a frame.
- the absorption layer may also be designed as a component of a basically arbitrary construction, e.g. in the form of a part of a piece of furniture or a sound-absorbing partition or protective wall (for example, as a substitute for a plasterboard).
- the absorbent layer can also withstand greater mechanical stress, i. it is characterized, for example, by from a particularly high in comparison with conventional sound absorbers high ball impact safety, shock resistance, resistance to breakage, dimensional stability, dimensional stability, scratch resistance, abrasion resistance, tear resistance and / or elasticity.
- the surface of the absorption layer air- and / or waterproof (or water-repellent), so that the absorber according to the invention, for example, can also be used in environments with increased hygiene requirements and / or increased humidity or moisture.
- the absorption layer of the absorber according to the invention can also in particular in conjunction with elastically resilient and / or soft open-pore porous materials (eg via a point, line and / or sheet-like connection area) as a floor covering or used as a substructure of a floor.
- elastically resilient and / or soft open-pore porous materials eg via a point, line and / or sheet-like connection area
- a sound absorption can be combined with a vibration isolation or impact sound insulation.
- the absorption layer has a specific flow resistance in the range of 50-5000 Pa * s / m or N * s / m 2 .
- the flow resistance of the absorption layer depends on its thickness and on the porosity of the open-pore porous material, the "porosity” referring to the ratio of the void volume to the total volume (void volume + solid volume) of the material.
- the absorption layer is supported so that it can be excited to piston-like vibrations, i. by sound action, the absorption layer can not only in bending vibration, but also in a piston-like, i. at least approximately rectilinear, oscillation, be excited.
- the absorption layer can be stored on an air cushion, wherein the mass of the absorption layer as the oscillating mass and the air cushion as a "spring" form an oscillatory system.
- Absorber materials can additionally be arranged in the area of the air cushion, s.u.
- the natural frequency of the absorption layer with respect to the piston-like vibrations is in the range between 10 Hz and 2000 Hz.
- the natural frequencies of the absorption layer are in comparison with, e.g. between 0.00005 Hz and 200 Hz.
- the (eg in the form of a plate formed) absorption layer can for example be loosely inserted into a frame, so that the frame, for example, although a lateral guidance of the absorption layer causes, but it is in a direction perpendicular to its main extension plane back and forth movable.
- no frame is used, but the absorption layer is otherwise stored so that it can perform free bending-like movements, for example, the absorption layer is hung like a lamella.
- a floating storage of the absorption layer on a (eg elastic) carrier is also used.
- the acoustic absorber has a mass element connected to the absorption layer for varying the natural frequencies of the absorption layer, wherein the mass element can influence the natural frequencies with respect to the bending vibrations of the absorption layer and / or with respect to piston-like vibrations of the absorption layer.
- the mass element is designed in the form of one or more material regions and in particular also has a porous material.
- the mass element is formed of a non-porous material.
- any geometries are conceivable, e.g. square, circular, polygonal, knobbed, conical, also in the form of multidimensional patterns and / or fractals.
- the mass element also has a plurality of grid-like structures arranged at a predetermined distance from one another.
- the inventive acoustic absorber can have means for generating a restoring force on the absorption layer.
- These means are used in particular to be able to tune the natural frequencies of bending vibrations of the absorption layer or possibly of piston-like vibrations of the absorption layer on.
- the means comprise an air-filled volume adjacent to the absorption layer ("air spring").
- the air-filled volume is formed only by incorporation of the absorption layer in a cavity or as a conclusion of a cavity.
- the absorber may consist only of the absorption layer and be used as the ceiling plate of a room, the absorption layer being e.g. is placed loosely in a ceiling frame, so that behind the absorption layer, i. adjacent to a side of the absorption layer facing away from the space, there is an air-filled volume into which the absorption plate can move.
- the means comprise an elastic element coupled to the absorption layer.
- the absorption layer is mounted on this elastic element, in particular point, line, or planar.
- the elastic member may also comprise a mechanical spring formed in another way.
- the elastic element is formed by an element made of an open-pore porous material, the spring-like with the absorption layer (in particular in one piece) is connected.
- the elastic element is formed by bending at least a portion of the absorption layer, so that the elastic element is connected via a resilient curvature with the rest of the absorption layer and extends correspondingly at an angle to the rest of the absorption layer.
- the angle between the elastic element and the absorption layer can be selected depending on the application (installation situation, mounting options, etc.) of the acoustic absorber, for example in the range between 30 ° and 45 °.
- the acoustic absorber according to the invention can also have means for damping bending vibrations and / or piston-like vibrations of the absorption layer.
- the damping means can cooperate with the means for exerting a restoring force on the absorption layer or at the same time be realized by this.
- an elastic element via which a restoring force can be exerted on the absorption layer, will also bring about a certain damping of vibrations of the absorption layer.
- the damping means comprise separate elements, e.g. a damping element attached to a spring connected to the absorption layer.
- the damping means comprise an opening through which air can flow out of an air-filled volume adjacent to the absorption layer, wherein the outflow of air through this opening absorbs energy from vibrations of the air molecules in the air-filled volume which have been excited by vibrations of the absorption layer , can be dissipated.
- the open-pored porous material of the absorption layer is in the form of a compacted (and in particular also ductile) nonwoven fabric.
- a "densified" nonwoven is a nonwoven material whose surface density has been increased by appropriate means such as needling or crimping.
- several nonwoven layers made of flexible organic fibers, such as aramids or other organic synthetic fibers such as polypropylene, viscose, polyacrylonitrile, polyamides or polyesters are used and needled several times with needles perpendicular to the nonwoven plane top and / or underside needles or other Way interconnected and condensed.
- the plurality of interconnected nonwoven layers of the absorption layer may consist of the same fiber material or at least partially made of different fiber materials.
- the nonwoven material of the absorption layer is compressed so that it has a flexural rigidity corresponding to the flexural rigidity of a layer of wood or plexiglass having the same dimensions.
- the densified web e.g. by mechanical needling with a perforation (e.g., in the form of a "micro-perforation", i.e., creating micrometer-sized diameter orifices) to reduce the flow resistance of the compacted web.
- a perforation e.g., in the form of a "micro-perforation", i.e., creating micrometer-sized diameter orifices
- This perforation arises, in particular, in that additional interconnected cavities are formed in the compacted nonwoven material, so that the perforated and compacted nonwoven material is, of course, also an "open-pored porous" material.
- nonwoven which has fibers with a larger diameter compared to fibers of a conventional absorber material, so that even with a high compression of the nonwoven, a flow through the absorption layer or at least a flow into the absorption layer is possible.
- the absorption layer consisting of a compacted non-woven material can, in principle, be processed like a conventional solid material board, e.g. by tacking, nailing, screwing, gluing, gluing, wedging, profiling, structuring, perforating, deforming, dyeing, and / or candling. Methods of making the densified nonwoven layer will be discussed in more detail below.
- the open-pore porous material of the absorption layer comprises first fibers of a first material and second fibers of a second material.
- the first fibers are plastic fibers and the second fibers are bicomponent fibers.
- the first fibers have a higher viscosity (as a measure of the interaction of the fiber molecules with one another, ie for the "internal friction" of the fibers) than the second fibers.
- the first fibers are plastic fibers and the second fibers are metal fibers.
- the first and the second fibers are made of different plastics. In this way, a flexurally elastic open-pore porous plate can be produced, which has a high flexural elasticity due to the less viscous second fibers and thus reacts immediately to a given sound pressure and vibrates.
- the absorption layer has an internal friction which dampens the excited vibrations of the absorption layer, so that more energy is withdrawn from a sound field impinging on the absorption layer than when using an absorption layer containing only one viscosity fibers, or when using a conventional absorber.
- the less viscous fibers are able to absorb more energy (in the form of elastic energy) than the higher viscous fibers, while conversely the higher viscous fibers can convert more energy to heat than the less viscous fibers.
- the ratio of the bending stiffness of the absorption layer to the damping can be adjusted.
- a higher-viscosity fiber type or in addition, another correspondingly viscous binder may also be used, e.g. a viscous liquid.
- the absorption layer has on one side, which is to be turned to a sound source, a layer for reducing the sound wave attenuation by the open-pored porous material.
- the layer is produced by melting a surface area of the absorption layer ("skinning"). This has the particular purpose of avoiding overdamping of higher frequencies, since the air itself as a carrier medium of the sound waves attenuates even at high frequencies stronger than at lower frequencies.
- an additional material may be applied to the surface to form the coating (e.g., impregnation, bonding and / or coating).
- the absorption layer can also be provided with a porous, air-permeable, light and / or thin plaster application. This could create an optically seamless surface.
- the absorption layer of the pores of the open-pored porous material has different openings, which in particular have dimensions (for example width or diameter) which is greater than the average pore dimensions of the open-pore porous material.
- additional openings are generated whose dimensions are in the range of pore dimensions.
- the sound absorption can be further increased specifically in a frequency range.
- the openings are slit-like (e.g., in the form of a micro-slot).
- the shape of the openings can in this case also extend in patterns and in a plurality of spatial directions, ie, for example, also have sections which extend at an angle to the thickness direction of the absorption layer.
- at least one of the openings extends considered single and / or multiple corrugated, rounded, conical, serrated, etc. along the thickness direction of the absorption layer.
- the openings may also be arranged in elevations (eg, curved or step-like) and / or bulges of a surface of the absorption layer.
- At least some of the openings may also be such that they do not completely penetrate the absorption layer but have a depth that is smaller than the thickness of the absorption layer.
- the depth of such openings may be considered as a resonator neck length of a Helmholtz resonator, wherein the residual thickness of the absorption layer not penetrated by these openings constitutes a flow resistance located immediately at the mouth surface of the resonator necks formed through the openings. An additional damping of these "resonator necks" can thus be omitted.
- Resonator necks of a Helmholtz resonator can be e.g. also form in that one edge of the opening protrudes from the remaining surface of the absorption layer.
- Such a structure may e.g. be generated by an opening is introduced into a survey of the surface.
- a Helmholtz resonator may also be made by creating a continuous opening in the absorption layer and forming this opening at least on one side with a sound absorbing layer, e.g. is made identical to the absorption layer of an open porous material, is closed.
- the absorption layer in which the resonator opening is provided is connected via its surface to a further absorption layer, which has dimensions similar to the absorption layer with the resonator opening and runs continuously in the region of the resonator opening.
- the acoustic absorber according to the invention can have means for generating a tensile stress in the absorption layer in order to be able to vary its bending stiffness.
- the means for generating a tensile stress comprise a mechanism (eg a frame) with which the edge (or at least a portion of the edge) of the absorption layer can be clamped and over which the absorption layer can be stretched in the manner of a membrane in order to increase the natural frequencies of the absorption layer change.
- the absorption layer formed by the open-pored porous material is a first absorption layer of the absorber, wherein the absorber has, in addition to the first absorption layer, a second absorption layer likewise formed from an open-pored porous material.
- a volume may be formed, e.g. can be filled with air (or any other gas) to cause the already mentioned above air suspension of the absorption layer.
- the volume between the absorption layers may be formed such that vibration energy from the absorption layer over the volume, i. via a coupling of the vibrating absorption layer (the "vibration mass") to the air spring, can be dissipated.
- the air-filled volume is configured to be in fluid communication with the environment of the absorber, whereby by discharging and flowing air into the volume, energy from sound waves excited in the air-filled volume dissipates, i. can be converted into heat energy.
- the air-filled volume is limited by a frame having at least one opening through which there is a flow connection of the air-filled volume to the surroundings of the absorber.
- an acoustically insulating material e.g. an open-pore porous material, arranged, which serves in particular in addition to an air filling for damping vibrations (bending and possibly piston-like vibrations) of at least one of the absorption layers.
- the two absorption layers may differ in their properties, e.g. also be formed of different porous materials open porous. It is also conceivable that the two absorption layers have different dimensions, e.g. Have thicknesses.
- the first absorption layer has a higher flexural rigidity than the second absorption layer, for example in that for the first absorption layer, another porous material is used porous and / or the first absorption layer is thicker than the second absorption layer.
- the first absorption layer has a higher basis weight than the second absorption layer.
- the two absorption layers differ; It is also possible that two identical absorption layers are provided or at least two absorption layers, which are formed from identical open-pored porous materials.
- the absorber is more than two Has absorption layers, wherein the number and the configuration of the absorption layers can be selected depending on the intended use of the absorber.
- a plurality of absorption layers of the absorber can also be connected to one another and in particular can be arranged adjacent to one another with their surfaces (which extend perpendicular to the thickness direction of the layers) (sandwich structure).
- the absorption layers of a sandwich structure can be joined together by gluing, welding, fusing and / or clawing.
- the absorber comprises two layers of the same material or of different porous and porous materials with a relatively thinner layer with a relatively higher densification of the material and with a further relatively thicker layer with a relatively lower densification.
- the higher density layer faces a sound source, with the higher density layer e.g. has a much higher stiffness than the less densified thicker layer.
- an areal relatively thinner area with higher compression and / or higher rigidity and a relatively thicker area with relatively less densification and / or less rigidity may be formed.
- the thinner area of the material, which is over-compacted and / or stiffened more highly, can be produced by progressive unilateral compression and stiffening of the material from one side
- the different absorption layers can be connected to one another at points or surfaces, preferably by adhesive bonding, fusion, holding together by frames or holding structures of solid materials, foaming of plastic, elastic or rigid foamable materials, spraying or application of liquid or plastically moldable materials.
- the absorbing layer facing a sound source is perforated or slit in a relatively higher density and / or stiffer layer.
- the change in the thickness of the layer facing away from the sound source i. their configuration in different thickness, in particular affects the range of the absorption effect in the low-frequency range, in particular in the manner of a film or plate resonant absorber or membrane absorber.
- two or more absorption layers are combined, i. h mounted and connected in rows, wherein the density of the second, third or each successive the sound source facing higher density layer a negative influence on the absorption effect by disturbing reflections within the overall structure are avoided.
- the connection is made, for example, by spot or surface adhesive bonding, fusion, holding together by means of frames or holding structures of solid materials, foaming of plastic, elastic or rigid foamable materials, spraying or application of liquid or plastically moldable materials.
- each higher-density and higher stiffened layer Due to the open-pored porous properties of each higher-density and higher stiffened layer, a reduction in the increase by the absorption effect counteracting reflections within the absorber structure is avoided.
- a mechanical vibration exciter to the higher density and / or stiffened layer or frame or support constructions connected thereto, e.g.
- the effect that the absorber is the broadband airborne sound radiator.
- the absorber according to the invention can also have at least one sound absorption layer, which is not formed from an open-pore porous fiber material (but for example from a foam). It is also conceivable that the absorption layer is arranged on a particularly elastic carrier (eg a carrier plate), wherein the carrier is formed in particular from a porous material.
- a particularly elastic carrier eg a carrier plate
- the carrier is formed in particular from a porous material.
- piston-shaped and / or bending oscillations in the carrier can also be excited, so that the design (eg material, dimensions, type of attachment, type of adhesion) of the carrier with regard to a tuning optimization of the absorption and / or Sound insulation properties of the acoustic absorber according to the invention can be carried out.
- the absorber of the present invention may also include one (or more) further air-permeable layer (e.g., a perforated surface or lattice structure) and / or one (or more) other air-enclosing or air-impermeable layers (e.g., a film).
- the further air-impermeable layer e.g., steel
- the further layers can at least approximately have the area dimensions of the absorption layer. However, it is also conceivable that at least some of the further layers (relative to the surface) are smaller than the absorption layer and / or have a different geometry.
- the absorption layer has a first portion which is movable relative to a second portion, so that e.g. a folding of the layer is possible.
- the absorbent layer may also have more than one (e.g., elongate or pointy) hinge, such that the absorbent layer is e.g. accordion-like with uniform or different intervals of the folding can be pulled apart and compressed.
- the absorbent layer may be folded over an elongate hinge (or joints) along a line parallel to a side edge of the absorbent layer. A punctiform joint allows a scissor-like fanning of the absorption layer.
- X ⁇ ⁇ d ⁇ 0 ⁇ c 0
- the height of the flow resistance, or factor X would have to be adapted to the respective thickness in the manufacturing process.
- the above variant of the invention makes it possible to adjust the setting of the factor X over the fanning of the absorption layer.
- the edge of the absorption layer is at least partially stored in a frame.
- the edge in the frame can be set so that the edge region (or at least portions of the edge region) of the absorption layer can at least substantially not be excited to vibrate.
- the "edge" of the absorption layer bounds the absorption layer in a direction perpendicular to its thickness direction.
- the storage of the absorption layer in a frame is not mandatory, as already mentioned above.
- the material layer is used as the "absorption layer" in the above-described acoustic absorber of the present invention. Accordingly, the material layer can be compressed or foamed until it has a bending stiffness of 10 to 100 Nm 2 , in particular between 10 and 30 Nm 2 , in another example, the layer is densified or foamed so far that their lowest natural frequency with respect to bending vibrations below 300 Hz.
- the material layer has, in particular in order to achieve the most uniform pore sizes possible (cavity sizes, the voids formed between the fibers of the web) multilayer fiber webs, in particular of highly flexible organic fibers, for example of organic synthetic fibers such as polypropylene, viscose, polyacrylonitrile, polyamides or polyester ,
- the compacting of the material layer formed by a plurality of nonwoven layers is accomplished by needling and / or pressing.
- the material layer it is alternatively or additionally also possible for the nonwoven layers of the material layer to be connected to one another and / or preconsolidated in another way.
- a binder in the form of latex and / or in the form of a thermally activatable binder e.g. in the form of bicomponent fibers.
- the nonwoven material layer can be compressed by means of a press to the desired stiffness and compressed in this way. After pressing, the material layer can be needled again and pressed again after this re-needling. Of course, the steps of needling / crimping the material layer may be repeated as often as necessary for the desired flexural rigidity and / or air permeability of the material layer.
- a nonwoven material layer having a flexural rigidity e.g. the flexural rigidity of a wooden panel (e.g., birch or oak), a wood-based panel, or a plexiglass panel of comparable (especially identical) dimensions is equal to or better than that.
- a feed rate i. the speed at which the material layer is passed through a needle device, which is significantly lower than the feed rates used in the needling of a conventional nonwoven fabric.
- a feed rate in the range of 0.50 m / minute to 3 m / minute, in particular between 0.5 m / minute and 2 m / minute is used.
- the needling of the material layer after compression may serve to create a perforation (in particular a microperforation) or a partial perforation in the densified material layer, i. to increase the number of interconnected voids between the fibers of the layer to reduce the flow resistance of the material layer.
- perforation or partial perforation of the material layer may be accomplished by other mechanical methods (e.g., drilling, water jet perforation) and / or thermal methods (e.g., hot needling, laser perforation).
- the elasticity of the material layer can also be changed (in particular increase) by needling and / or calendering, for example. It should be noted that as
- Material of the material layer can be used in particular nonwovens, which have a high breaking strength, so that bending vibrations of high amplitude can be excited in the Matehal für assembly without damaging the material layer.
- nonwovens are used whose fibers have a suitable length (e.g., at least 40 mm) and which are sufficiently elastic and break-resistant.
- the material layer can in particular have different types of fibers and / or nonwoven layers which are formed from different types of fibers.
- a fiber of a second type of fiber e.g., a viscosity different from the first type of fiber
- a viscosity different from the first type of fiber can be blended into a starting material of a first type of fiber.
- the densified material layer is thermoformed to bring it into a desired shape for an acoustic absorber.
- the fibers of a nonwoven used to produce the material layer may also have a coating or be provided with a coating during the production of the material layer.
- it may be a soil-repellent coating of the fibers and / or a coating for coloring, flame retardance, odor control, increase in hydrolysis resistance, UV protection, soil repellency, water repellency of the fibers, e.g. a plasma polymer functional coating, a Teflon coating and / or a nanocoating comes into question.
- residues of the nonwoven materials used during the production of the material layer can be recycled and, in turn, serve as starting material for producing a further material layer.
- the waste is shredded and then processed according to the method described above for producing the material layer.
- the absorption layer has open-cell foams, fiber materials, minerals, glass materials, ceramics, plastics, but also solid materials such as cellular concrete or the like.
- glass covers glass itself and also all glass-related building materials, such as Plexiglas, acrylic glass, organic glass, such as crystal glass.
- a "plastic” is, for example, PVC, polyethylene, polypropylene, polyester, polystyrene, including polystyrene with glass fiber, rubber, rubber including natural rubber, in particular foams of plastics and plastic films of the aforementioned materials.
- the absorption layer may also include metal such as aluminum, lead, copper, brass, iron, steel including finishings such as stainless steel and steel alloys and cast steel, malleable cast iron, sintered metals such as zinc, tin, gold and platinum.
- the Figures 1A to 1D each show a plate-shaped absorption layer 1 of the acoustic absorber according to the invention, wherein the absorption layers each have a continuously varying mass density.
- the mass density is continuously from a first side 11 (which is eg a sound source turn) to one of the first side opposite second side 12 of the absorption layer 1 continuously smaller.
- the mass density of the absorption layer increases towards the center (viewed in the thickness direction) continuously, while according to Fig. 1C the mass density continuously decreases towards the center of the layer.
- the mass density changes periodically in a direction transverse to the thickness direction of the absorption layer, ie, along a direction parallel to the main extension plane of the absorption layer.
- the absorption layer 1 has, at least in sections, a rib structure 100.
- the absorption layer is wave-shaped.
- the absorption layer 1 has a honeycomb structure at least in sections, in particular in order to increase its stability.
- the absorption layer 1 may have a base body 13 (for example rectangular in cross-section), from which (eg periodically arranged) in cross-section rectangular (FIG. FIGS. 2A and B ) Structures 131 protrude.
- a base body 13 for example rectangular in cross-section
- FIGS. 2A and B the absorption layer 1
- FIGS. 2C and D stand from the main body a plurality of structures 132 with a curved surface.
- at least one side of the absorption layer has a rib structure as in FIGS FIGS. 2A and B or wave structure according to the FIGS. 2C and D on.
- FIGS. 3A and B relate to a further embodiment of the absorber according to the invention, wherein Fig. 3A the absorber in a view from above and Fig. 3B show the absorber in a perspective view.
- an absorption layer 1 is mounted in a support frame 2.
- the storage of the absorption layer in the frame can take place such that an air volume which acts as a spring coupled to the absorption layer is present on a rear side of the absorption layer facing away from a sound source.
- FIGS. 4A and 4B illustrate other elastic elements that can be coupled to the absorption layer of the absorber.
- FIGS. 4A and 4B illustrated.
- a plurality of spring elements 3 are arranged on a back side 12 of the absorption layer, wherein the spring elements are positioned so close to each other that a sheet-like storage of the absorption layer is formed.
- a large-area elastic element which is, for example, approximately over the entire surface of the back of the absorption layer coupled thereto.
- FIG. 4B Another possibility of the resilient mounting of the absorption layer 1 shows the Fig. 4B , Thereafter, a plurality of spring elements 3 are arranged spaced from each other, wherein in each case one side of the spring elements is coupled to the back of the absorption layer 1.
- the spring elements 3, in particular a punctiform storage of the absorption layer 1 can be realized.
- a mass element 4 is applied to the actual absorption layer 1, which is formed in particular from a different material than the absorption layer.
- the mass element serves, in particular, to tune the natural frequencies of the absorption layer 1.
- the mass element may have any desired geometries, for example, like a lattice (according to the sectional view of FIG Fig. 5A or the top view of Fig. 5B ) or diamond-like ( FIGS. 5C and D ).
- the mass element 4 is at least partially disposed in depressions of the surface of the absorption layer 1.
- FIGS. 6A to C refer to further embodiments of the absorber according to the invention.
- an absorption layer 1 of the absorber is mounted on a frame 2, that between a bottom portion 21 of the frame 2 and a back side 12 of the absorption layer 1, an air volume 5 is present, which acts as an elastic element and together with the absorption layer 1, a mass-spring -System forms, which can be excited by the action of sound waves on a front side 11 of the absorption layer 1 to vibrate.
- the frame has, in addition to the bottom plate 21 side walls 22 which project perpendicularly from the bottom plate 21 and a side edge 14 of the absorption layer border.
- the absorber according to the invention may also have other means for generating a restoring force on the absorption layer, in particular, the side walls of the frame may be formed elastically.
- the absorption layer 1 may be coupled to elastic elements, for example in the form of a spring 3 or an elastic wall 31, which absorb a vibration of the absorption layer.
- the elastic elements are in the region of their side edge 14 with the absorption layer coupled, for example, two elastic elements are provided, which are coupled at opposite side edge portions of the absorption layer with this; see. FIGS. 6B and C ,
- FIG. 7 illustrates the sound absorption behavior of air in relation to different air volumes.
- air has an increased sound absorption compared to lower frequencies.
- the absorption layer of the absorber according to the invention may have on its side facing the sound source a coating 150, for example in the form of a "skin formation", which can be produced by melting a surface region of the absorption layer; see. Fig. 9 ,
- FIG. 8 shows the absorption behavior of various conventional open-pore porous absorber in comparison with the flexurally elastic absorption layer (dots) of the absorber according to the invention. While conventional absorbers absorb much less in the low frequency range (below about 600 Hz) than in the higher frequency range (above 600 Hz), the flexurally elastic absorption layer also absorbs in the region below 600 Hz due to the excited bending vibrations.
- the absorption behavior of a plate resonator (triangles) is shown, which absorbs almost exclusively due to excited bending vibrations, i. almost exclusively in the low-frequency sound range, while the absorption layer of the absorber according to the invention absorbs both in the low-frequency and in the higher-frequency range.
- the absorption layer 1 is wave-shaped and has openings 17 on the side flanks of the "wave" (FIG. Fig. 10A ). It is also possible that the absorption layer has no through openings ( Fig. 10B ), but openings that are covered on one side of the absorption layer (in particular by an insulating material 180), so that in a sense a variety of Helmholtz resonators arise. It is also possible to arrange several such absorption layers one above the other ( Fig. 10D ). In another example, the openings 17 are formed in elevations 171 of a surface 11 of the absorption layer (FIG. Fig. 10C ).
- the absorption layer 1 is mounted in a frame 2 so that it can be clamped across the frame transversely to its thickness direction in order to tune the natural frequencies of the absorption layer.
- FIGS. 12A to E refer to a variant of the absorber according to the invention, according to which two absorption layers 1a, 1b are provided.
- the two absorption layers 1a, 1b are arranged at a distance and parallel to each other and in particular integrally connected to one another via a side edge 1c.
- openings 6 can be provided in the side edge 1c through which air can flow out of a volume 5 extending between the absorption layers 1a, 1b ( Fig. 12B ).
- an insulating material 7 may be arranged in the volume 5, in particular such that the volume is at least approximately completely filled ( Fig. 12C ).
- the absorption layers 1a and 1b do not have to be connected to each other in one piece, but they can also be shaped flat without a side edge ( Fig. 12D ), the volume 5 being analogous to Fig. 12C can be filled with an insulating material 7.
- the insulating material is in particular such that it only partially fills the volume 5 ( Fig. 12E) ,
- the absorber according to the invention may have an insulating material on its rear side ( Fig. 13A ).
- the absorption layer may include air inclusions 8 (FIG. Fig. 13B ) or another, eg lattice-shaped material 9 (eg of metal) in order to increase its bending stiffness ( Fig. 13C ).
- FIG. 14 Another embodiment of the absorber according to the invention shows Fig. 14 , Thereafter, a plurality of absorption layers 1a-1d are arranged at a distance and parallel to each other.
- the absorption layers 1a-1d are connected to each other via hinge elements 9, so that the spacing of the absorption layers relative to each other can be changed in the manner of a concertina.
- the joint elements may in particular be formed by flexible pieces of material (eg of a textile material).
- Fig. 15 relates to an embodiment of the movable element 1 'of the acoustic transducer according to the invention.
- the movable member 1 ' has a thickness increasing from its center to the side edge 15 (ie, along the main extension planes of the movable member). This serves in particular to suppress reflections of bending waves excited in the movable element on the side edge.
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Description
Die Erfindung betrifft einen akustischen Absorber gemäß dem Oberbegriff des Anspruchs 1 sowie ein Verfahren zum Herstellen eines akustischen Absorbers gemäß dem Oberbegriff des Anspruchs 13.The invention relates to an acoustic absorber according to the preamble of
Aus dem Stand der Technik ist bekannt, offenporig poröse Materialien zur Schalldämpfung zu verwenden, wobei unter einem "porösen" Material ein Material verstanden wird, das einen gewissen Anteil von Hohlraumeinschlüssen aufweist Von einem "offenporig" porösen Material wird insbesondere gesprochen, wenn der überwiegende Anteil der Hohlräume des Materials in Strömungsverbindung mit anderen Hohlräumen steht. So können Schallwellen aufgrund der miteinander verbundenen Hohlräume des offenporig porösen Materials in das Material eindringen und es zumindest teilweise durchdringen.It is known from the prior art to use open-pore porous materials for soundproofing, wherein a "porous" material is understood to mean a material which has a certain proportion of void inclusions. An "open-porous" porous material is particularly preferred if the predominant proportion the cavities of the material are in fluid communication with other cavities. Thus, sound waves can penetrate into the material due to the interconnected cavities of the porous material open porous and at least partially penetrate it.
Die Energie der in das offenporig poröse Material eindringenden Schallwellen wird in dem Material zumindest teilweise in Wärmeenergie umgewandelt, insbesondere dadurch, dass die mit der Schallwelle verbundene Bewegungsenergie von Luftmolekülen durch Reibung der Luftmolekülen an dem die Hohlräume umschließenden Material in Wärme umgesetzt wird. Dieser Absorptionsmechanismus führt dazu, dass Schallwellen mit kürzerer Wellenlänge, d.h. höherer Frequenz, stärker absorbiert werden als tiefe Frequenzen.The energy of the sound waves penetrating into the open-pore porous material is at least partially converted into heat energy in the material, in particular by the fact that the kinetic energy of air molecules connected to the sound wave is converted into heat by friction of the air molecules at the material enclosing the cavities. This absorption mechanism results in shorter wavelengths of sound, i. higher frequency, are absorbed more than low frequencies.
Beispielsweise offenbart die
Darüber hinaus sind aus dem Stand der Technik akustische Wandler, z.B. in Form von Flächenlautsprechern bekannt, die jedoch häufig eine stark nichtlineare Frequenzcharakteristik aufweisen.In addition, prior art acoustic transducers, e.g. in the form of area loudspeakers, but often having a strong non-linear frequency characteristic.
Das der Erfindung zugrunde liegende Problem besteht darin, einen akustischen Absorber zur Absorption von Schallwellen zu schaffen, der auf möglichst einfache Weise herstellbar ist und dennoch eine Schallabsorption über einen breiteren Frequenzbereich ermöglicht. Der Erfindung liegt des Weiteren das Problem zugrunde, ein Verfahren zum Herstellen eines derartigen akustischen Absorbers anzugeben.The problem underlying the invention is to provide an acoustic absorber for the absorption of sound waves, which can be produced in the simplest possible way and still allows sound absorption over a wider frequency range. The invention is further based on the problem of specifying a method for producing such an acoustic absorber.
Diese Probleme werden durch den akustischen Absorber mit den Merkmalen des Anspruchs 1 und durch das Verfahren mit den Merkmalen des Anspruchs 13 gelöst. Weiterbildungen der Erfindung sind in den abhängigen Ansprüchen angegeben.These problems are solved by the acoustic absorber having the features of
Danach wird ein akustischer Absorber zur Schalldämpfung bereitgestellt, der eine aus einem offenporig porösen Material gebildete Absorptionsschicht aufweist, wobei das offenporig poröse Material derart biegeelastisch ist, dass die Absorptionsschicht beim Auftreffen von Schallwellen zu Biegeschwingungen mit Eigenfrequenzen der Absorptionsschicht (1) angeregt wird und der Absorber aufgrund des Hineinströmens von Luft in das offenporig poröse Material der Absorptionsschicht Schallwellen eines ersten Frequenzbereichs und durch die Anregung von Biegeschwingungen der Absorptionsschicht Schallwellen eines zweiten Frequenzbereichs, der niedrigere Frequenzen umfasst als der erste Frequenzbereich, absorbieren kann, wobei das offenporig poröse Material aus mehreren Vlieslagen besteht und zur Bindung der Vlieslagen und/oder der Fasern der Vlieslagen ein Bindemittel in Form von Latex und/oder ein thermisch aktivierbares Bindemittel aufweist.Thereafter, an acoustic absorber for sound damping is provided which has an absorbent layer formed from an open porous material, wherein the porous porous material is so elastic that the absorption layer is excited upon impact of sound waves to bending vibrations with natural frequencies of the absorption layer (1) and the absorber due to the inflow of air into the porous porous material of the absorption layer, sound waves of a first frequency range and by the excitation of bending vibrations of the absorption layer can absorb sound waves of a second frequency range comprising lower frequencies than the first frequency range, the porous porous material consisting of multiple nonwoven layers and for bonding the nonwoven layers and / or the fibers of the nonwoven layers has a binder in the form of latex and / or a thermally activatable binder.
Es ist natürlich auch möglich, dass sich der erste und der zweite Frequenzbereich teilweise überlappen. Insbesondere können die Eigenschaften der Absorptionsschicht so gewählt werden, dass die beiden Frequenzbereiche in einem vorbestimmten Überlappungsfrequenzbereich überlappen, um in diesem Bereich eine erhöhte Absorption zu erzeugen.Of course, it is also possible that the first and the second frequency range partially overlap. In particular, the properties of the absorption layer can be selected such that the two frequency ranges overlap in a predetermined overlap frequency range in order to produce increased absorption in this region.
Die Absorptionsschicht kombiniert somit zwei Absorptionsmechanismen miteinander, nämlich die typische Absorption eines offenporig porösen Materials bei höheren Frequenzen mit der Absorption über die Anregung von Biegeschwingungen bei niedrigeren Frequenzen. Insbesondere ist damit gemeint, dass die Schallabsorption in dem tieferen Frequenzbereich, die auf die Anregung von Biegeschwingungen der Absorptionsschicht zurückgeht, größer ist als eine möglicherweise noch in diesem Frequenzbereich vorhandene geringe AbsorptionThe absorption layer thus combines two absorption mechanisms together, namely the typical absorption of an open porous material at higher frequencies with absorption via the excitation of bending vibrations at lower frequencies. In particular, this means that the sound absorption in the lower frequency range, which is due to the excitation of bending vibrations of the absorption layer is greater than a possibly present in this frequency range low absorption
durch die Durchströmung des offenporig porösen Materials. Somit ist der Absorber auch mit nur einer Absorptionsschicht in der Lage, Schallwellen über einen großen Frequenzbereich zu dämpfen, d.h. es ist nicht notwendig, zusätzlich zu der offenporig porösenthrough the flow through the porous material porous. Thus, even with only one absorption layer, the absorber is able to dampen sound waves over a wide frequency range, ie it is not necessary, in addition to the porous porous
Absorptionsschicht andere Mittel zur Dämpfung der Schallwellen bei niedrigeren Frequenzen vorzusehen. Mit dem erfindungsgemäßen Absorber werden zwei unterschiedliche Absorptionsmechanismen somit gewissermaßen parallel geschaltet.Absorption layer to provide other means for damping the sound waves at lower frequencies. With the absorber according to the invention, two different absorption mechanisms are thus to some extent connected in parallel.
Zu den porösen Materialien zählen alle porösen und faserartigen Materialien wie Textilien, Vlies, Teppich, Schaumstoff, Mineralwolle, Baumwolle, spezielle Akustikputze, Blähglasgranulate und so genannte haufwerksporige Materialien, die Schallenergien absorbieren, indem sie Schwingungen der Luftteilchen durch Reibung in Wärmeenergie umwandeln.Porous materials include all porous and fibrous materials such as textiles, nonwoven, carpet, foam, mineral wool, cotton, special acoustic plasters, expanded glass granules, and so-called porous materials that absorb sound energy by frictionally converting vibrations of the air particles into heat energy.
Dünne offenporig poröse Absorptionsschichten wie Textilien absorbieren bevorzugt im hochfrequenten Bereich. Um auch bei dünneren Materialstärken eine breitbandigere und hohe Absorption zu erzielen, werden z.B. mehrere offenporig poröse Absorptionsschichten mit immer höher werdendem Strömungswiderstand hintereinander angeordnet. Hierbei wird insbesondere die Schicht mit dem geringsten Strömungswiderstand der Schallquelle zugewandt. Hierdurch wird insbesondere sichergestellt, dass die Absorptionsschichten, die der Schallquelle abgewandt angeordnet sind, Ihre Wirksamkeit durch die Abdeckung durch die übrigen Absorptionsschichten nicht verlieren.Thin porous porous absorption layers such as textiles preferably absorb in the high-frequency range. In order to achieve a broader band and high absorption even with thinner material thicknesses, e.g. several porous porous absorption layers with increasing flow resistance arranged one behind the other. In this case, in particular the layer with the lowest flow resistance of the sound source is turned. This ensures in particular that the absorption layers, which are arranged facing away from the sound source, do not lose their effectiveness through the cover by the other absorption layers.
Insbesondere kann das Verhältnis der Biegesteifigkeit (bzw. der Masse, Dicke und/oder der Abmessungen) zum Strömungswiderstand der Absorptionsschicht in Abhängigkeit der vorgesehenen Anwendung des akustischen Absorbers gewählt werden, z.B. um ein Dröhnen in kleineren Räumen oder eine relativ zu tieferen Frequenzen zu starke Absorption hoher Frequenzen zu vermeiden. Insbesondere kann durch geeignete Anpassung der Absorptionseigenschaften des erfindungsgemäßen Absorbers im tieferen Frequenzbereich dem Ausbilden eines "Flatterechos" z.B. bei Auskleidung von Räumen mit dem Absorber entgegengewirkt werden.In particular, the ratio of the flexural rigidity (or mass, thickness and / or dimensions) to the flow resistance of the absorbent layer may be selected depending on the intended application of the acoustic absorber, e.g. To avoid a drone in smaller rooms or a relatively lower frequencies too strong absorption of high frequencies. In particular, by suitable adaptation of the absorption properties of the absorber according to the invention in the lower frequency range, the formation of a "flutter echo", e.g. be counteracted when lining rooms with the absorber.
Des Weiteren kann der erfindungsgemäße akustische Absorber, dadurch, dass er sowohl in tieferen als auch in höheren Frequenzbereichen absorbiert, eine Kombination verschiedener Absorbertypen ersetzen, wodurch z.B. Kosten, Gewicht und Montagezeit verringert werden können. Allerdings kann der erfindungsgemäße akustische Absorber natürlich durchaus mit konventionellen Absorbertypen kombiniert werden, z.B. kann die Absorptionsschicht des erfindungsgemäßen akustischen Absorbers als Abschlussfläche (Mündungsfläche) eines Helmholtzresonators anstelle des konventionellerweise als Abschlussfläche verwendeten Dämmstoffs eingesetzt werden.Furthermore, by absorbing both lower and higher frequency ranges, the inventive acoustic absorber can replace a combination of different types of absorbers, thereby reducing costs, weight and assembly time, for example. However, the acoustic absorber according to the invention can of course certainly be combined with conventional absorber types, for example the absorption layer of the acoustic absorber according to the invention can be used as the end face (muzzle surface) of a Helmholtz resonator instead of the insulating material conventionally used as end face.
In einem Ausführungsbeispiel der Erfindung weist die Absorptionsschicht eine Biegesteifigkeit
Insbesondere weist die Absorptionsschicht eine derartige Biegesteifigkeit auf, dass die Eigenfrequenz der Absorptionsschicht in Bezug auf Biegeschwingungen unterhalb von 600 Hz, insbesondere unterhalb von 300 Hz oder insbesondere von 200 Hz liegt.In particular, the absorption layer has such a flexural rigidity that the natural frequency of the absorption layer with respect to flexural vibrations is below 600 Hz, in particular below 300 Hz or in particular of 200 Hz.
In Bezug auf Richtungen, die parallel zur Haupterstreckungsebene der Absorptionsschicht verlaufen, kann die Absorptionsschicht eine ähnliche Biegesteifigkeit aufweisen. Dies ist jedoch nicht zwingend, sondern die Biegesteifigkeiten in Bezug auf unterschiedliche Belastungsrichtungen können natürlich auch unterschiedlich sein.With respect to directions parallel to the main extension plane of the absorption layer, the absorption layer may have a similar flexural rigidity. However, this is not mandatory, but the bending stiffness with respect to different load directions can of course also be different.
Damit auch größere Biegeschwingungsamplituden ohne Beschädigung der Absorptionsschicht möglich sind, kann die Absorptionsschicht eine insbesondere im Vergleich mit konventionellen Absorbern (die z.B. einen Mineralfaserdämmstoff oder einen offenzellig porösen Schaumstoff aufweisen) erhöhte Biegeelastizität, Duktilität und/oder Bruchfestigkeit aufweisen. Beispielsweise ist das offenporig poröse Material der Absorptionsschicht duktiler als Glas oder als Steinwolle, d.h. insbesondere, dass das offenporig poröse Material der Absorptionsschicht eine größere Bruchfestigkeit als diese Materialien aufweist. In einem Beispiel liegt die zulässige Höchstzugkraft des offenporig porösen Materials der Absorptionsschicht mindestens 10 Prozent über derjenigen von Glas.In order to allow greater bending vibration amplitudes without damaging the absorbent layer, the absorbent layer may have increased flexural elasticity, ductility and / or crush resistance, particularly in comparison with conventional absorbers (e.g., having a mineral fiber or open cell foam). For example, the porous-porous material of the absorbent layer is more ductile than glass or rock wool, i. in particular, that the open-pore porous material of the absorption layer has a greater breaking strength than these materials. In one example, the maximum permissible tensile force of the porous porous material of the absorbent layer is at least 10 percent greater than that of glass.
Darüber hinaus kann die Absorptionsschicht eine Flächenmasse im Bereich von 30g/m2 bis 20kg/m2, insbesondere zwischen 1 bis 5 kg oder zwischen 1 bis 3 kg aufweisen. Allerdings muss die Flächenmasse nicht über die Absorptionsschicht hinweg konstant sein, sondern sie kann auch ortsabhängig sein, d.h. die Flächenmasse kann z.B. in Dickenrichtung der Absorptionsschicht und/oder in einer Richtung senkrecht zur Dickenrichtung variieren. Darüber hinaus kann die Massendichte des offenporig porösen Materials der Absorptionsschicht allgemein ortsabhängig sein, d.h. über die Absorptionsschicht hinweg und nicht nur in Dickenrichtung variieren.In addition, the absorption layer may have a basis weight in the range of 30 g / m 2 to 20 kg / m 2 , in particular between 1 to 5 kg or between 1 to 3 kg. However, the basis weight does not have to be constant over the absorption layer, but it may also be location-dependent, ie the basis weight may vary, for example, in the thickness direction of the absorption layer and / or in a direction perpendicular to the thickness direction. In addition, the bulk density of the porous porous material of the absorption layer may be generally location-dependent, ie vary across the absorption layer and not only in the thickness direction.
Beispielsweise nimmt die Massendichte des offenporig porösen Materials in Dickenrichtung der Absorptionsschicht zu (progressive Verdichtung) oder sie nimmt von einer Mitte der Absorptionsschicht zu ihren (senkrecht zur Dickenrichtung verlaufenden) Oberflächen zu- oder ab. Die Massendichte der Absorptionsschicht kann auch bezogen auf einen ersten Querschnitt der Absorptionsschicht in Dickenrichtung zu- und bezogen auf eine zweiten, zum ersten Querschnitt beabstandeten Querschnitt abnehmen. Dies kann auch alternierend erfolgen, d.h. entlang der Länge oder der Breite der Absorptionsschicht betrachtet, nimmt die Massendichte der Absorptionsschicht in Dickenrichtung abwechselnd zu und ab. Darüber hinaus kann die Massendichte auch nach Art einer Wabenstruktur zur Erhöhung der Stabilität der Absorptionsschicht verlaufen.For example, the bulk density of the porous open-pore material increases in the thickness direction of the absorption layer (progressive densification) or increases or decreases from a center of the absorption layer to its (perpendicular to the thickness direction) surfaces. The mass density of the absorption layer may also increase in the thickness direction relative to a first cross section of the absorption layer and decrease with respect to a second cross section which is at a distance from the first cross section. This can also be done alternately, i. When viewed along the length or the width of the absorption layer, the bulk density of the absorption layer alternately increases and decreases in the thickness direction. In addition, the bulk density can also extend in the manner of a honeycomb structure to increase the stability of the absorption layer.
Unter der "Absorptionsschicht" des Absorbers wird insbesondere ein flächiges Gebilde verstanden, das sich entlang einer Haupterstreckungsebene erstreckt und dessen Abmessung senkrecht zu der Haupterstreckungsebene klein gegenüber den Abmessungen parallel zur Haupterstreckungsebene ist. Beispielsweise ist die Absorptionsschicht in Form einer Platte ausgebildet, wobei der akustische Absorber beispielsweise zumindest im Wesentlichen nur aus dieser Platte besteht. Insbesondere ist die Absorptionsschicht z.B. zumindest näherungsweise rechteckig ausgebildet, z.B. mit einer Länge zwischen 30 und 150 cm und einer Breite zwischen 30 und 100 cm (mit z.B. einer Dicke zwischen 5 und 20 mm). Allerdings ist die Erfindung natürlich nicht auf eine bestimmte Form der Absorptionsschicht festgelegt, sondern die Form und die Abmessungen der Absorptionsschicht können im Prinzip beliebig in Abhängigkeit von der vorgesehenen Anwendung des akustischen Absorbers gewählt werden.The "absorption layer" of the absorber is understood in particular to be a planar structure which extends along a main extension plane and whose dimension perpendicular to the main extension plane is small in relation to the dimensions parallel to the main extension plane. For example, the absorption layer is formed in the form of a plate, wherein the acoustic absorber, for example, consists at least substantially only of this plate. In particular, the absorption layer is e.g. at least approximately rectangular, e.g. with a length between 30 and 150 cm and a width between 30 and 100 cm (with for example a thickness between 5 and 20 mm). Of course, the invention is of course not limited to a particular form of absorption layer, but the shape and dimensions of the absorption layer can in principle be chosen arbitrarily depending on the intended application of the acoustic absorber.
Die Absorptionsschicht muss jedoch nicht unbedingt plan verlaufen, sondern sie kann sich auch zumindest abschnittsweise gekrümmt erstrecken, so dass sie z.B. in Bezug auf eine konkave oder konvexe Oberfläche angeordnet werden kann. Des Weiteren ist es möglich, über die Stärke der Krümmung der Absorptionsschicht eine Einstellung der Eigenfrequenzen der Absorptionsschicht bzw. eine Streuung oder Bündelung der einfallenden Schallwellen vorzunehmen.However, the absorption layer does not necessarily have to be flat, but may also extend at least in sections in a curved manner, so that it may be e.g. with respect to a concave or convex surface. Furthermore, it is possible to make an adjustment of the natural frequencies of the absorption layer or a scattering or bundling of the incident sound waves via the strength of the curvature of the absorption layer.
Die Absorptionsschicht weist beispielsweise eine Dicke im Bereich von 0,1 mm bis 100 mm, insbesondere im Bereich zwischen 3 mm und 20 mm, auf, wobei darauf hingewiesen wird, dass es nicht zwingend ist, dass die Absorptionsschicht eine konstante Dicke besitzt. Es ist auch denkbar, dass die Dicke ortsabhängig ist, d.h. sie kann in einer Richtung parallel zu einer Haupterstreckungsebene, entlang derer sich die Absorptionsschicht variieren, um z.B. die Schallabsorption durch Oberflächenvergrößerung der Absorptionsschicht zu erhöhen und/oder eine diffus schallreflektierende Oberfläche zu erzeugen (z.B. durch eine wellenförmige Ausgestaltung zumindest einer Oberfläche der Absorptionsschicht).The absorption layer has, for example, a thickness in the range from 0.1 mm to 100 mm, in particular in the range between 3 mm and 20 mm, it being understood that it is not mandatory for the absorption layer to have a constant thickness. It is also conceivable that the thickness is location-dependent, ie it can be in a direction parallel to a main plane along which vary the absorption layer, for example, to increase the sound absorption by increasing the surface of the absorption layer and / or to produce a diffuse sound-reflecting surface (eg by a wave-shaped configuration of at least one surface of the absorption layer).
Es ist auch möglich, dass die Absorptionsschicht zwar flach (d.h. zumindest im Wesentlichen nicht gekrümmt) verläuft, jedoch nicht durchgehend ausgeformt ist, sondern z.B. eine (insbesondere rechteckige oder kreisförmige) Öffnung aufweist. Beispielsweise kann die Absorptionsschicht so beschaffen sein, dass sie nach Art eines Rahmens eine (zentrale) Öffnung umläuft.It is also possible for the absorption layer to be flat (i.e., at least substantially non-curved), but not continuous, but e.g. has a (in particular rectangular or circular) opening. For example, the absorption layer may be designed such that it circulates around a (central) opening in the manner of a frame.
In diesem Zusammenhang wird darauf hingewiesen, dass die Absorptionsschicht auch als ein Bauteil einer im Prinzip beliebigen Konstruktion ausgestaltet sein kann, z.B. in Form eines Teiles eines Möbelstücks oder einer schalldämpfenden Trenn- oder Schutzwand (z.B. als Ersatz einer Gipskartonplatte). Insbesondere kann sich die Absorptionsschicht aufgrund ihrer Biegefestigkeit auch stärkerer mechanischer Belastung widersetzen, d.h. sie zeichnet sich z.B. aus durch eine insbesondere im Vergleich mit konventionellen Schallabsorbern hohe Ballwurfsicherheit, Stoßsicherheit, Bruchsicherheit, Formstabilität, Formbeständigkeit, Kratzunempfindlichkeit, Scheuerfestigkeit, Reißfestigkeit und/oder Elastizität.In this context, it should be noted that the absorption layer may also be designed as a component of a basically arbitrary construction, e.g. in the form of a part of a piece of furniture or a sound-absorbing partition or protective wall (for example, as a substitute for a plasterboard). In particular, due to its flexural strength, the absorbent layer can also withstand greater mechanical stress, i. it is characterized, for example, by from a particularly high in comparison with conventional sound absorbers high ball impact safety, shock resistance, resistance to breakage, dimensional stability, dimensional stability, scratch resistance, abrasion resistance, tear resistance and / or elasticity.
Darüber hinaus besteht die Möglichkeit, die Oberfläche der Absorptionsschicht luft- und/oder wasserdicht (bzw. wasserabweisend) herzustellen, so dass der erfindungsgemäße Absorber z.B. auch in Umgebungen mit erhöhten Hygieneanforderungen und/oder erhöhter Feuchtigkeit oder Nässe verwendet werden kann.In addition, it is possible to make the surface of the absorption layer air- and / or waterproof (or water-repellent), so that the absorber according to the invention, for example, can also be used in environments with increased hygiene requirements and / or increased humidity or moisture.
Weitere Verwendungsmöglichkeiten des erfindungsgemäßen Absorbers sind beispielsweise:
- Lautsprechermembran und/oder Mikrofonmembran (s.u.);
- Kanalschalldämpfer
- Schallschleusen
- Schallschirm;
- Schallkapsel;
- schalldämmende Trennwand;
- Anordnen des Absorbers unter einer Tapete (insbesondere einer luftdurchlässigen Glasfaser- oder Textiltapete);
- Anordnen des Absorbers unter einem luftdurchlässigen Putz (haufwerksporig);
- Anordnen des Absorbers unter einem Furnier (z.B. einem mikroperforierten Furnier);
- Projektionsfläche und Absorberfläche, bei gleichzeitiger Schallabstrahlung;
- Mikrofon-Lautsprecher Trennwand;
- Mikrofon-Lautsprecher Segel.
- Speaker diaphragm and / or microphone diaphragm (see below);
- channel sound absorbers
- sound locks
- Sound screen;
- Sound chamber;
- sound-insulating partition;
- Placing the absorber under a wallpaper (in particular an air-permeable glass fiber or textile wallpaper);
- Placing the absorber under an air-permeable plaster (hspwerksporig);
- Placing the absorber under a veneer (eg a microperforated veneer);
- Projection surface and absorber surface, with simultaneous sound radiation;
- Microphone speaker partition;
- Microphone speaker sails.
Die Absorptionsschicht des erfindungsgemäßen Absorbers kann zudem auch insbesondere im Verbund mit elastisch federnden und/oder weichen offenporig porösen Materialien (z.B. über einen punkt-, linien- und/oder flächenförmigen Verbindungsbereich) als Fußbodenbelag oder als Unterkonstruktion eines Fußbodens verwendet werden. Hierdurch kann eine Schallabsorption mit einer Schwingungsisolierung bzw. Trittschallisolierung kombiniert werden.The absorption layer of the absorber according to the invention can also in particular in conjunction with elastically resilient and / or soft open-pore porous materials (eg via a point, line and / or sheet-like connection area) as a floor covering or used as a substructure of a floor. As a result, a sound absorption can be combined with a vibration isolation or impact sound insulation.
In einer anderen Ausgestaltung der Erfindung weist die Absorptionsschicht einen spezifischen Strömungswiderstand im Bereich von 50 - 5000 Pa*s/m bzw. N*s/m2 auf. Insbesondere hängt der Strömungswiderstand der Absorptionsschicht von ihrer Dicke und von der Porösität des offenporig porösen Materials ab, wobei sich die "Porösität" auf das Verhältnis des Hohlraumvolumens zu dem Gesamtvolumen (Hohlraumvolumen + Feststoffvolumen) des Materials bezieht.In another embodiment of the invention, the absorption layer has a specific flow resistance in the range of 50-5000 Pa * s / m or N * s / m 2 . In particular, the flow resistance of the absorption layer depends on its thickness and on the porosity of the open-pore porous material, the "porosity" referring to the ratio of the void volume to the total volume (void volume + solid volume) of the material.
Beispielsweise wird für die Porosität σ angegeben:
Gemäß einer anderen Weiterbildung der Erfindung ist die Absorptionsschicht so gelagert, dass sie zu kolbenartigen Schwingungen angeregt werden kann, d.h. durch Schalleinwirkung kann die Absorptionsschicht nicht nur in Biegeschwingung, sondern auch in eine kolbenartige, d.h. zumindest näherungsweise geradlinige, Schwingung, angeregt werden. Dadurch ist es möglich, das Absorptionsspektrum des akustischen Absorbers zu verbreitern oder noch genauer auf eine vorgegebene Frequenz (oder mehrere Frequenzen) oder einen Frequenzbereich abzustimmen. Beispielsweise kann die Absorptionsschicht auf einem Luftpolster gelagert werden, wobei die Masse der Absorptionsschicht als Schwingmasse und das Luftpolster als "Feder" ein schwingfähiges System bilden. Im Bereich des Luftpolsters können zusätzlich Absorbermaterialien angeordnet sein, s.u.According to another embodiment of the invention, the absorption layer is supported so that it can be excited to piston-like vibrations, i. by sound action, the absorption layer can not only in bending vibration, but also in a piston-like, i. at least approximately rectilinear, oscillation, be excited. This makes it possible to widen the absorption spectrum of the acoustic absorber or even more precisely to a predetermined frequency (or multiple frequencies) or tune a frequency range. For example, the absorption layer can be stored on an air cushion, wherein the mass of the absorption layer as the oscillating mass and the air cushion as a "spring" form an oscillatory system. Absorber materials can additionally be arranged in the area of the air cushion, s.u.
Beispielsweise liegt die Eigenfrequenz der Absorptionsschicht in Bezug auf die kolbenartigen Schwingungen im Bereich zwischen 10Hz und 2000Hz Die Eigenfrequenzen der Absorptionsschicht liegen im Vergleich z.B. zwischen 0,00005 Hz und 200 Hz.For example, the natural frequency of the absorption layer with respect to the piston-like vibrations is in the range between 10 Hz and 2000 Hz. The natural frequencies of the absorption layer are in comparison with, e.g. between 0.00005 Hz and 200 Hz.
Die (z.B. in Form einer Platte ausgebildete) Absorptionsschicht kann z.B. lose in einen Rahmen eingelegt werden, so dass der Rahmen z.B. zwar eine seitliche Führung der Absorptionsschicht bewirkt, sie jedoch in einer Richtung senkrecht zu ihrer Haupterstreckungsebene hin und her bewegbar ist. In einer anderen Variante wird kein Rahmen verwendet, sondern die Absorptionsschicht wird auf andere Weise so gelagert, dass sie freie biegeartige Bewegungen ausführen kann, z.B. wird die Absorptionsschicht lamellenartig aufgehängt. Eine andere Möglichkeit ist eine schwimmende Lagerung der Absorptionsschicht auf einem (z.B. elastischen) Träger. Es sind natürlich weitere Arten der Lagerung der Absorptionsschicht möglich, z.B. ein zumindest teilweises Einspannen der Absorptionsschicht oder ein nur teilweises Auflegen oder nur teilweises Freischwingenlassen der Absorptionsschicht bzw. eine Kombination unterschiedlicher Arten der Lagerung, s.u..The (eg in the form of a plate formed) absorption layer can for example be loosely inserted into a frame, so that the frame, for example, although a lateral guidance of the absorption layer causes, but it is in a direction perpendicular to its main extension plane back and forth movable. In another variant, no frame is used, but the absorption layer is otherwise stored so that it can perform free bending-like movements, for example, the absorption layer is hung like a lamella. Another possibility is a floating storage of the absorption layer on a (eg elastic) carrier. There are of course other types of Storage of the absorption layer possible, for example, an at least partial clamping of the absorption layer or only a partial laying on or only partial free release of the absorption layer or a combination of different types of storage, see below.
Gemäß einer anderen Variante der Erfindung weist der akustische Absorber ein mit der Absorptionsschicht verbundenes Massenelement zum Verändern der Eigenfrequenzen der Absorptionsschicht auf, wobei das Masseelement die Eigenfrequenzen in Bezug auf die Biegeschwingungen der Absorptionsschicht und/oder in Bezug auf kolbenartige Schwingungen der Absorptionsschicht beeinflussen kann. Beispielsweise ist das Masseelement in Form eines oder mehrerer Materialbereiche ausgebildet und weist insbesondere ebenfalls ein poröses Material auf. Es ist jedoch im Prinzip auch denkbar, dass das Masseelement aus einem nicht porösen Material gebildet ist. Neben einer punktförmigen Ausgestaltung des Masseelementes sind im Prinzip beliebige Geometrien denkbar, z.B. quadratisch, kreisförmig, polygonal, noppenförmig, kegelförmig, dies auch in Form mehrdimensionaler Muster und/oder Fraktale. Insbesondere weist das Masseelement auch mehrere rasterartig mit einem vorgegebenen Abstand zueinander angeordnete Strukturen auf.According to another variant of the invention, the acoustic absorber has a mass element connected to the absorption layer for varying the natural frequencies of the absorption layer, wherein the mass element can influence the natural frequencies with respect to the bending vibrations of the absorption layer and / or with respect to piston-like vibrations of the absorption layer. For example, the mass element is designed in the form of one or more material regions and in particular also has a porous material. However, it is also conceivable in principle that the mass element is formed of a non-porous material. In addition to a punctiform configuration of the mass element, in principle any geometries are conceivable, e.g. square, circular, polygonal, knobbed, conical, also in the form of multidimensional patterns and / or fractals. In particular, the mass element also has a plurality of grid-like structures arranged at a predetermined distance from one another.
Darüber hinaus kann der erfindungsgemäße akustische Absorber Mittel zur Erzeugung einer Rückstellkraft auf die Absorptionsschicht aufweisen. Diese Mittel dienen insbesondere dazu, die Eigenfrequenzen von Biegeschwingungen der Absorptionsschicht oder ggf. von kolbenartigen Schwingungen der Absorptionsschicht weiter abstimmen zu können. Beispielsweise umfassen die Mittel ein an die Absorptionsschicht angrenzenden luftgefülltes Volumen ("Luftfeder"). Hier ist denkbar, dass das luftgefüllte Volumen erst durch einen Einbau der Absorptionsschicht in einen Hohlraum oder als Abschluss eines Hohlraums entsteht. Etwa kann der Absorber lediglich aus der Absorptionsschicht bestehen und als Deckenplatte eines Raumes verwendet werden, wobei die Absorptionsschicht z.B. lose in einen Deckenrahmen eingelegt wird, so dass hinter der Absorptionsschicht, d.h. angrenzend an eine dem Raum abgewandte Seite der Absorptionsschicht, ein luftgefülltes Volumen vorhanden ist, in das sich die Absorptionsplatte hinein bewegen kann.In addition, the inventive acoustic absorber can have means for generating a restoring force on the absorption layer. These means are used in particular to be able to tune the natural frequencies of bending vibrations of the absorption layer or possibly of piston-like vibrations of the absorption layer on. For example, the means comprise an air-filled volume adjacent to the absorption layer ("air spring"). Here it is conceivable that the air-filled volume is formed only by incorporation of the absorption layer in a cavity or as a conclusion of a cavity. For example, the absorber may consist only of the absorption layer and be used as the ceiling plate of a room, the absorption layer being e.g. is placed loosely in a ceiling frame, so that behind the absorption layer, i. adjacent to a side of the absorption layer facing away from the space, there is an air-filled volume into which the absorption plate can move.
Gemäß einer anderen Variante der Erfindung umfassen die Mittel ein mit der Absorptionsschicht gekoppeltes elastisches Element. Beispielsweise ist die Absorptionsschicht über dieses elastische Element gelagert, insbesondere punkt-, linien-, oder flächenartig. Das elastische Element kann jedoch auch eine auf andere Weise ausgebildete mechanische Feder aufweisen.According to another variant of the invention, the means comprise an elastic element coupled to the absorption layer. For example, the absorption layer is mounted on this elastic element, in particular point, line, or planar. However, the elastic member may also comprise a mechanical spring formed in another way.
Darüber hinaus ist auch denkbar, dass das elastische Element durch ein Element aus einem offenporig porösen Material gebildet ist, das federartig mit der Absorptionsschicht (insbesondere einstückig) verbunden ist. Beispielsweise wird das elastische Element durch Abbiegen mindestens eines Abschnitts der Absorptionsschicht ausgebildet, so dass das elastische Element über eine federnde Krümmung mit der übrigen Absorptionsschicht verbunden ist und sich entsprechend unter einem Winkel zu der übrigen Absorptionsschicht erstreckt. Der Winkel zwischen dem elastischen Element und der Absorptionsschicht kann je nach Anwendung (Einbausituation, Befestigungsmöglichkeiten, etc.) des akustischen Absorbers gewählt werden, z.B. im Bereich zwischen 30° und 45°.In addition, it is also conceivable that the elastic element is formed by an element made of an open-pore porous material, the spring-like with the absorption layer (in particular in one piece) is connected. For example, the elastic element is formed by bending at least a portion of the absorption layer, so that the elastic element is connected via a resilient curvature with the rest of the absorption layer and extends correspondingly at an angle to the rest of the absorption layer. The angle between the elastic element and the absorption layer can be selected depending on the application (installation situation, mounting options, etc.) of the acoustic absorber, for example in the range between 30 ° and 45 °.
Es ist natürlich auch möglich, dass mehrere elastische Elemente vorgesehen sind, die z.B. an einander gegenüberliegenden Seiten der Absorptionsschicht mit dieser verbunden sind.Of course, it is also possible to provide a plurality of elastic elements, e.g. On opposite sides of the absorption layer are connected thereto.
Der erfindungsgemäße akustische Absorber kann zudem auch Mittel zum Dämpfen von Biegeschwingungen und/oder kolbenartiger Schwingungen der Absorptionsschicht aufweisen. Insbesondere können die Dämpfungsmittel mit den Mitteln zum Ausüben einer Rückstellkraft auf die Absorptionsschicht zusammenwirken oder auch gleichzeitig durch diese realisiert werden. Beispielsweise wird ein elastisches Element, über das eine Rückstellkraft auf die Absorptionsschicht ausgeübt werden kann, auch eine gewisse Dämpfung von Schwingungen der Absorptionsschicht bewirken.The acoustic absorber according to the invention can also have means for damping bending vibrations and / or piston-like vibrations of the absorption layer. In particular, the damping means can cooperate with the means for exerting a restoring force on the absorption layer or at the same time be realized by this. For example, an elastic element, via which a restoring force can be exerted on the absorption layer, will also bring about a certain damping of vibrations of the absorption layer.
Es ist jedoch auch möglich, dass die Dämpfungsmittel separate Elemente umfassen, z.B. ein Dämpfungselement, das an einer mit der Absorptionsschicht verbundenen Feder angebracht ist. In einer anderen Variante umfassen die Dämpfungsmittel eine Öffnung, über die Luft aus einem an die Absorptionsschicht angrenzenden luftgefüllten Volumen abströmen kann, wobei durch das Abströmen von Luft über diese Öffnung Energie von Schwingungen der Luftmoleküle in dem luftgefüllten Volumen, die durch Schwingungen der Absorptionsschicht angeregt wurden, dissipiert werden kann.However, it is also possible that the damping means comprise separate elements, e.g. a damping element attached to a spring connected to the absorption layer. In another variant, the damping means comprise an opening through which air can flow out of an air-filled volume adjacent to the absorption layer, wherein the outflow of air through this opening absorbs energy from vibrations of the air molecules in the air-filled volume which have been excited by vibrations of the absorption layer , can be dissipated.
Gemäß einer anderen Ausgestaltung der Erfindung ist das offenporig poröse Material der Absorptionsschicht in Form eines verdichteten (und insbesondere auch duktilen) Vlieses ausgebildet. Ein "verdichtetes" Vlies ist ein nicht gewebtes Material, dessen Flächendichte durch geeignete Maßnahme wie Nadeln oder Verpressen erhöht wurde. Beispielsweise werden zum Herstellen des verdichteten Vlieses mehrere Vlieslagen aus flexiblen organischen Fasern, z.B. Aramiden oder aus anderen organischen Synthesefasern wie Polypropylen, Viskose, Polyacrylnitril, Polyamide oder Polyester, verwendet und mehrfach mit Nadeln senkrecht zur Vliesebene ober- und/oder unterseitig genadelt oder auf andere Weise miteinander verbunden und verdichtet. Die mehreren miteinander verbundenen Vlieslagen der Absorptionsschicht können aus demselben Fasermaterial oder auch zumindest teilsweise aus unterschiedlichen Fasermaterialien bestehen.According to another embodiment of the invention, the open-pored porous material of the absorption layer is in the form of a compacted (and in particular also ductile) nonwoven fabric. A "densified" nonwoven is a nonwoven material whose surface density has been increased by appropriate means such as needling or crimping. For example, several nonwoven layers made of flexible organic fibers, such as aramids or other organic synthetic fibers such as polypropylene, viscose, polyacrylonitrile, polyamides or polyesters, are used and needled several times with needles perpendicular to the nonwoven plane top and / or underside needles or other Way interconnected and condensed. The plurality of interconnected nonwoven layers of the absorption layer may consist of the same fiber material or at least partially made of different fiber materials.
Insbesondere ist das Vliesmaterial der Absorptionsschicht derart verdichtet, dass sie eine Biegesteifigkeit aufweist, die der Biegesteifigkeit einer aus Holz oder Plexiglas gebildeten Schicht mit den gleichen Abmessungen entspricht.In particular, the nonwoven material of the absorption layer is compressed so that it has a flexural rigidity corresponding to the flexural rigidity of a layer of wood or plexiglass having the same dimensions.
Es ist zudem möglich, dass das verdichtete Vlies z.B. durch mechanisches Nadeln mit einer Perforation (z.B. in Form einer "Mikroperforation", d.h. das Erzeugen von Öffnungen mit einem Durchmesser im Mikrometerbereich) versehen wird, um den Strömungswiderstand des verdichteten Vlieses zu reduzieren. Diese Perforation entsteht insbesondere dadurch, dass in dem verdichteten Vliesmaterial zusätzliche miteinander verbundene Hohlräume entstehen, so dass es sich bei dem perforierten und verdichten Vliesmaterial selbstverständlich auch um ein "offenporig poröses" Material handelt.It is also possible that the densified web, e.g. by mechanical needling with a perforation (e.g., in the form of a "micro-perforation", i.e., creating micrometer-sized diameter orifices) to reduce the flow resistance of the compacted web. This perforation arises, in particular, in that additional interconnected cavities are formed in the compacted nonwoven material, so that the perforated and compacted nonwoven material is, of course, also an "open-pored porous" material.
Des Weiteren kann ein Vlies verwendet werden, das Fasern mit einem im Vergleich zu Fasern eines konventionellen Absorbermaterials größeren Durchmesser aufweist, so dass auch bei einer hohen Verdichtung des Vlieses eine Strömung durch die Absorptionsschicht oder zumindest eine Strömung in die Absorptionsschicht hinein möglich ist.Furthermore, it is possible to use a nonwoven which has fibers with a larger diameter compared to fibers of a conventional absorber material, so that even with a high compression of the nonwoven, a flow through the absorption layer or at least a flow into the absorption layer is possible.
Die aus einem verdichten Vlies bestehenden Absorptionsschicht kann im Prinzip wie eine übliche feste Werkstoffplatte verarbeitet werden, z.B. durch Tackern, Nageln, Schrauben, Verleimen, Verkleben, Verkeilen, Profilieren, Strukturieren, Perforieren, Verformen, Färben, und/oder Durchleuchten. Auf Verfahren zum Herstellen der verdichteten Vliesschicht wird weiter unten noch ausführlicher eingegangen.The absorption layer consisting of a compacted non-woven material can, in principle, be processed like a conventional solid material board, e.g. by tacking, nailing, screwing, gluing, gluing, wedging, profiling, structuring, perforating, deforming, dyeing, and / or candling. Methods of making the densified nonwoven layer will be discussed in more detail below.
Gemäß einer Weiterbildung weist das offenporig poröse Material der Absorptionsschicht erste Fasern eines ersten Materials und zweite Fasern eines zweiten Materials auf. Beispielsweise sind die ersten Fasern Kunststofffasern und die zweiten Fasern Bikomponenten-Fasern.According to a development, the open-pore porous material of the absorption layer comprises first fibers of a first material and second fibers of a second material. For example, the first fibers are plastic fibers and the second fibers are bicomponent fibers.
Insbesondere weisen die ersten Fasern eine höhere Viskosität (als Maß für die Wechselwirkung der Fasermoleküle untereinander, d.h. für die "innere Reibung" der Fasern) als die zweiten Fasern auf. Dies kann z.B. dadurch realisiert werden, dass die ersten Fasern Kunststofffasern sind und die zweiten Fasern Metallfasern. Es jedoch auch denkbar, dass die ersten und die zweiten Fasern aus unterschiedlichen Kunststoffen hergestellt sind. Hierdurch kann eine biegeelastische offenporig poröse Platte hergestellt werden, welche aufgrund der weniger viskosen zweiten Fasern eine hohe Biegeelastizität aufweist und somit umgehend auf einen gegebenen Schalldruck reagiert und in Schwingungen gerät. Aufgrund der viskoseren ersten Fasern weist die Absorptionsschicht jedoch eine innere Reibung auf, die dämpfend auf die angeregten Schwingungen der Absorptionsschicht wirkt, so dass einem auf die Absorptionsschicht auftreffenden Schallfeld mehr Energie entzogen wird als bei Verwendung einer Absorptionsschicht, die Fasern nur einer Viskosität enthält, oder bei Verwendung eines konventionellen Absorbers.In particular, the first fibers have a higher viscosity (as a measure of the interaction of the fiber molecules with one another, ie for the "internal friction" of the fibers) than the second fibers. This can be realized, for example, in that the first fibers are plastic fibers and the second fibers are metal fibers. However, it is also conceivable that the first and the second fibers are made of different plastics. In this way, a flexurally elastic open-pore porous plate can be produced, which has a high flexural elasticity due to the less viscous second fibers and thus reacts immediately to a given sound pressure and vibrates. However, due to the more viscous first fibers, the absorption layer has an internal friction which dampens the excited vibrations of the absorption layer, so that more energy is withdrawn from a sound field impinging on the absorption layer than when using an absorption layer containing only one viscosity fibers, or when using a conventional absorber.
Insbesondere sind die weniger viskosen Fasern in der Lage, mehr Energie (in Form von elastischer Energie) aufzunehmen als die höher viskosen Fasern, während umgekehrt die höher viskosen Fasern eine größere Energiemenge in Wärme umwandeln können als die weniger viskosen Fasern.In particular, the less viscous fibers are able to absorb more energy (in the form of elastic energy) than the higher viscous fibers, while conversely the higher viscous fibers can convert more energy to heat than the less viscous fibers.
Über das Verhältnis zwischen dem Anteil der viskosen Fasern und dem Anteil der weniger viskosen Fasern kann das Verhältnis der Biegesteifigkeit der Absorptionsschicht zur Dämpfung eingestellt werden. Anstelle eines höherviskosen Fasertyps oder zusätzlich kann auch ein anderes entsprechend viskoses Bindemittel verwendet werden, z.B. eine viskose Flüssigkeit.By means of the ratio between the proportion of viscous fibers and the proportion of less viscous fibers, the ratio of the bending stiffness of the absorption layer to the damping can be adjusted. Instead of a higher-viscosity fiber type or in addition, another correspondingly viscous binder may also be used, e.g. a viscous liquid.
Gemäß einer anderen Ausgestaltung des akustischen Absorbers weist die Absorptionsschicht auf einer Seite, die einer Schallquelle zuzuwenden ist, eine Schicht zur Verminderung der Schallwellendämpfung durch das offenporig poröse Material auf. Beispielsweise wird die Schicht durch Aufschmelzen eines Oberflächenbereiches des Absorptionsschicht erzeugt ("Verhautung"). Dies hat insbesondere den Sinn, eine Überdämpfung höherer Frequenzen zu vermeiden, da die Luft als Trägermedium der Schallwellen selber bereits bei hohen Frequenzen stärker dämpft als bei niedrigeren Frequenzen. Es ist jedoch auch möglich, dass zum Ausbilden der Beschichtung ein zusätzliches Material auf die Oberfläche aufgebracht wird (z.B. Tränkung, Verklebung und/oder Beschichtung). Die Absorptionsschicht kann auch mit einem porösen, luftdurchlässigen, leichten und/oder dünnem Putzauftrag versehen werden. Hierdurch könnte eine optisch fugenlose Oberfläche erzeugt werden.According to another embodiment of the acoustic absorber, the absorption layer has on one side, which is to be turned to a sound source, a layer for reducing the sound wave attenuation by the open-pored porous material. For example, the layer is produced by melting a surface area of the absorption layer ("skinning"). This has the particular purpose of avoiding overdamping of higher frequencies, since the air itself as a carrier medium of the sound waves attenuates even at high frequencies stronger than at lower frequencies. However, it is also possible that an additional material may be applied to the surface to form the coating (e.g., impregnation, bonding and / or coating). The absorption layer can also be provided with a porous, air-permeable, light and / or thin plaster application. This could create an optically seamless surface.
In einer anderen Variante weist die Absorptionsschicht von den Poren des offenporig porösen Materials verschiedene Öffnungen auf, die insbesondere Abmessungen (z.B. Breite oder Durchmesser) besitzen der größer ist als die durchschnittlichen Porenabmessungen des offenporig porösen Materials. Allerdings ist es auch möglich, dass zusätzliche Öffnungen ("Mikroperforation") erzeugt werden, deren Abmessungen im Bereich der Porenabmessungen liegen. Mittels dieser zusätzlichen Öffnungen kann die Schallabsorption gezielt in einem Frequenzbereich weiter erhöht werden. Beispielsweise sind zumindest einige der Öffnungen schlitzartig (z.B. in Form eines Mikroschlitzes) ausgebildet.In another variant, the absorption layer of the pores of the open-pored porous material has different openings, which in particular have dimensions (for example width or diameter) which is greater than the average pore dimensions of the open-pore porous material. However, it is also possible that additional openings ("microperforation") are generated whose dimensions are in the range of pore dimensions. By means of these additional openings, the sound absorption can be further increased specifically in a frequency range. For example, at least some of the openings are slit-like (e.g., in the form of a micro-slot).
Die Form der Öffnungen kann hierbei auch in Mustern und sich in mehrere Raumrichtungen erstrecken, d.h. z.B. auch Abschnitt aufweisen, die sich abgewinkelt zur Dickenrichtung der Absorptionsschicht erstrecken. Beispielsweise verläuft zumindest eine der Öffnungen entlang der Dickenrichtung der Absorptionsschicht betrachtet einfach und/oder mehrfach gewellt, abgerundet, konisch, gezackt etc. Die Öffnungen können auch in (z.B. gewölbten oder stufenartigen) Erhebungen und/oder Ausbuchtungen einer Oberfläche der Absorptionsschicht angeordnet sein.The shape of the openings can in this case also extend in patterns and in a plurality of spatial directions, ie, for example, also have sections which extend at an angle to the thickness direction of the absorption layer. For example, at least one of the openings extends considered single and / or multiple corrugated, rounded, conical, serrated, etc. along the thickness direction of the absorption layer. The openings may also be arranged in elevations (eg, curved or step-like) and / or bulges of a surface of the absorption layer.
Zumindest einige der Öffnungen können auch beschaffen sein, dass sie die Absorptionsschicht nicht vollständig durchdringen, sondern eine Tiefe aufweisen, die kleiner als die Dicke der Absorptionsschicht ist. Die Tiefe derartiger Öffnungen kann als Resonatorhalslänge eines Helmholtzresonators betrachtet werden, wobei die von diesen Öffnungen nicht durchdrungene Restdicke der Absorptionsschicht einen Strömungswiderstand darstellt, der unmittelbar an der Mündungsfläche der durch die Öffnungen ausgebildeten Resonatorhälse angeordnet ist. Eine zusätzliche Bedämpfung dieser "Resonatorhälse" kann somit entfallen.At least some of the openings may also be such that they do not completely penetrate the absorption layer but have a depth that is smaller than the thickness of the absorption layer. The depth of such openings may be considered as a resonator neck length of a Helmholtz resonator, wherein the residual thickness of the absorption layer not penetrated by these openings constitutes a flow resistance located immediately at the mouth surface of the resonator necks formed through the openings. An additional damping of these "resonator necks" can thus be omitted.
Resonatorhälse eines Helmholtzresonator lassen sich z.B. auch dadurch ausbilden, dass ein Rand der Öffnung von der übrigen Oberfläche der Absorptionsschicht absteht. Eine derartige Struktur kann z.B. dadurch erzeugt werden, dass eine Öffnung in eine Erhebung der Oberfläche eingebracht wird.Resonator necks of a Helmholtz resonator can be e.g. also form in that one edge of the opening protrudes from the remaining surface of the absorption layer. Such a structure may e.g. be generated by an opening is introduced into a survey of the surface.
Ein Helmholtzresonator kann auch dadurch hergestellt werden, dass eine durchgehende Öffnung in der Absorptionsschicht erzeugt und diese Öffnung zumindest an einer Seite mit einer schallabsorbierenden Schicht, die z.B. identisch zu der Absorptionsschicht aus einem offenporig porösen Material hergestellt ist, verschlossen wird. Beispielsweise wird die Absorptionsschicht, in der die Resonatoröffnung vorgesehen ist, über ihre Oberfläche mit einer weiteren Absorptionsschicht, die ähnliche Abmessungen wie die Absorptionsschicht mit der Resonatoröffnung aufweist und die im Bereich der Resonatoröffnung durchgehend verläuft, verbunden. Darüber ist auch möglich, mehrere derartige Helmholtzresonator-Absorptionsschichten hintereinander anzuordnen.A Helmholtz resonator may also be made by creating a continuous opening in the absorption layer and forming this opening at least on one side with a sound absorbing layer, e.g. is made identical to the absorption layer of an open porous material, is closed. By way of example, the absorption layer in which the resonator opening is provided is connected via its surface to a further absorption layer, which has dimensions similar to the absorption layer with the resonator opening and runs continuously in the region of the resonator opening. In addition, it is also possible to arrange a plurality of such Helmholtz resonator absorption layers one behind the other.
Des Weiteren kann der erfindungsgemäße akustische Absorber Mittel zum Erzeugen einer Zugspannung in der Absorptionsschicht aufweisen, um deren Biegesteifigkeit variieren zu können. Insbesondere umfassen die Mittel zum Erzeugen einer Zugspannung einen Mechanismus (z.B. einen Rahmen), mit dem der Rand (oder zumindest einen Abschnitt des Randes) der Absorptionsschicht eingespannt und über den die Absorptionsschicht nach Art einer Membran gespannt werden kann, um die Eigenfrequenzen der Absorptionsschicht zu verändern.Furthermore, the acoustic absorber according to the invention can have means for generating a tensile stress in the absorption layer in order to be able to vary its bending stiffness. In particular, the means for generating a tensile stress comprise a mechanism (eg a frame) with which the edge (or at least a portion of the edge) of the absorption layer can be clamped and over which the absorption layer can be stretched in the manner of a membrane in order to increase the natural frequencies of the absorption layer change.
Gemäß einer weiteren Ausgestaltung der Erfindung stellt die durch das offenporig poröse Material gebildete Absorptionsschicht eine erste Absorptionsschicht des Absorbers dar, wobei der Absorber neben der ersten Absorptionsschicht eine ebenfalls aus einem offenporig porösen Material gebildete zweite Absorptionsschicht aufweist.According to a further embodiment of the invention, the absorption layer formed by the open-pored porous material is a first absorption layer of the absorber, wherein the absorber has, in addition to the first absorption layer, a second absorption layer likewise formed from an open-pored porous material.
Zwischen der ersten und der zweiten Absorptionsschicht kann ein Volumen ausgebildet sein, das z.B. mit Luft (oder einem beliebigen anderen Gas) gefüllt sein kann, um die bereits oben erwähnte Luftfederung der Absorptionsschicht zu bewirken. Zudem kann das Volumen zwischen den Absorptionsschichten so ausgebildet sein, dass Schwingungsenergie von der Absorptionsschicht über das Volumen, d.h. über eine Ankopplung der schwingenden Absorptionsschicht (der "Schwingungsmasse") an die Luftfeder, dissipiert werden kann.Between the first and second absorption layers, a volume may be formed, e.g. can be filled with air (or any other gas) to cause the already mentioned above air suspension of the absorption layer. In addition, the volume between the absorption layers may be formed such that vibration energy from the absorption layer over the volume, i. via a coupling of the vibrating absorption layer (the "vibration mass") to the air spring, can be dissipated.
Insbesondere ist das luftgefüllte Volumen so ausgestaltet, dass eine Strömungsverbindung zur Umgebung des Absorbers besteht, wobei durch Aus- und Einströmen von Luft in das Volumen Energie von in dem luftgefüllten Volumen angeregten Schallwellen dissipiert, d.h. in Wärmeenergie umgewandelt werden kann. Beispielsweise ist das luftgefüllte Volumen durch einen Rahmen begrenzt, der mindestens eine Öffnung aufweist, über die eine Strömungsverbindung des luftgefüllten Volumens zur Umgebung des Absorbers besteht.In particular, the air-filled volume is configured to be in fluid communication with the environment of the absorber, whereby by discharging and flowing air into the volume, energy from sound waves excited in the air-filled volume dissipates, i. can be converted into heat energy. For example, the air-filled volume is limited by a frame having at least one opening through which there is a flow connection of the air-filled volume to the surroundings of the absorber.
In einer anderen Variante ist in dem Volumen zwischen der ersten und der zweiten Absorptionsschicht ein akustisch dämmendes Material, z.B. ein offenporig poröses Material, angeordnet, das insbesondere zusätzlich zu einer Luftfüllung zur Dämpfung von Schwingungen (Biege- und ggf. kolbenartige Schwingungen) zumindest einer der Absorptionsschichten dient.In another variant, in the volume between the first and second absorption layers is an acoustically insulating material, e.g. an open-pore porous material, arranged, which serves in particular in addition to an air filling for damping vibrations (bending and possibly piston-like vibrations) of at least one of the absorption layers.
Die beiden Absorptionsschichten können sich in ihren Eigenschaften unterscheiden, z.B. auch aus unterschiedlichen offenporig porösen Materialien gebildet sein. Auch ist es denkbar, dass die beiden Absorptionsschichten unterschiedliche Abmessungen, z.B. Dicken aufweisen.The two absorption layers may differ in their properties, e.g. also be formed of different porous materials open porous. It is also conceivable that the two absorption layers have different dimensions, e.g. Have thicknesses.
Gemäß einer anderen Variante weist die erste Absorptionsschicht eine höhere Biegesteifigkeit als die zweite Absorptionsschicht auf, beispielsweise dadurch, dass für die erste Absorptionsschicht ein anderes offenporig poröses Material verwendet wird und/oder die erste Absorptionsschicht dicker als die zweite Absorptionsschicht ist. Insbesondere ist es auch möglich, dass die erste Absorptionsschicht eine höhere Flächenmasse als die zweite Absorptionsschicht aufweist.According to another variant, the first absorption layer has a higher flexural rigidity than the second absorption layer, for example in that for the first absorption layer, another porous material is used porous and / or the first absorption layer is thicker than the second absorption layer. In particular, it is also possible that the first absorption layer has a higher basis weight than the second absorption layer.
Selbstverständlich ist es nicht zwingend, dass sich die beiden Absorptionsschichten unterscheiden; es ist auch möglich, dass zwei identische Absorptionsschichten vorgesehen werden oder zumindest zwei Absorptionsschichten, die aus identischen offenporig porösen Materialien gebildet sind. Natürlich ist es auch möglich, dass der Absorber mehr als zwei Absorptionsschichten aufweist, wobei die Anzahl und die Ausgestaltung der Absorptionsschichten in Abhängigkeit von der vorgesehenen Verwendung des Absorbers gewählt werden kann. Insbesondere können mehrere Absorptionsschichten des Absorbers auch miteinander verbunden sein und insbesondere mit ihren Oberflächen (die sich senkrecht zur Dickenrichtung der Schichten erstrecken) aneinanderliegend angeordnet sein (Sandwichstruktur). Beispielsweise können die Absorptionsschichten einer Sandwichstruktur durch Verkleben, Verschweißen, Verschmelzen und/oder Verkrallen miteinander verbunden sein.Of course, it is not mandatory that the two absorption layers differ; It is also possible that two identical absorption layers are provided or at least two absorption layers, which are formed from identical open-pored porous materials. Of course, it is also possible that the absorber is more than two Has absorption layers, wherein the number and the configuration of the absorption layers can be selected depending on the intended use of the absorber. In particular, a plurality of absorption layers of the absorber can also be connected to one another and in particular can be arranged adjacent to one another with their surfaces (which extend perpendicular to the thickness direction of the layers) (sandwich structure). For example, the absorption layers of a sandwich structure can be joined together by gluing, welding, fusing and / or clawing.
Insbesondere weist der Absorber zwei Schichten desselben Materials oder unterschiedlicher offenporig und poröser Materialien mit einer im Verhältnis dünneren Schicht mit einer im Verhältnis höheren Verdichtung des Materials und mit einer weiteren im Verhältnis dickeren Schicht mit einer im Verhältnis geringeren Verdichtung auf. Beispielsweise ist die höher verdichtete Schicht einer Schallquelle zugewandt ist, wobei die höher verdichtete Schicht z.B. eine wesentlich höhere Steifigkeit als die weniger verdichtete dickere Schicht aufweist.In particular, the absorber comprises two layers of the same material or of different porous and porous materials with a relatively thinner layer with a relatively higher densification of the material and with a further relatively thicker layer with a relatively lower densification. For example, the higher density layer faces a sound source, with the higher density layer e.g. has a much higher stiffness than the less densified thicker layer.
Statt zweier Schichten desselben oder unterschiedlicher poröser offenporiger Materialien in einer Schicht gleichen Materials kann auch ein ganzflächiger verhältnismäßig dünnerer Bereich mit höherer Verdichtung und/ oder höherer Steifigkeit und ein verhältnismäßig dickerer Bereich mit verhältnismäßig geringerer Verdichtung und/oder geringerer Steifigkeit ausgebildet sein. Darüber hinaus kann der ganzflächige höher verdichtete und/oder höher versteifte dünnere Bereich des Materials durch progressive einseitige Verdichtung und Versteifung des Materials von einer Seite aus erzeugt seinInstead of two layers of the same or different porous open-pored materials in a layer of the same material, an areal relatively thinner area with higher compression and / or higher rigidity and a relatively thicker area with relatively less densification and / or less rigidity may be formed. Moreover, the thinner area of the material, which is over-compacted and / or stiffened more highly, can be produced by progressive unilateral compression and stiffening of the material from one side
Des Weiteren können die unterschiedlichen Absorptionsschichten punktuell oder flächig miteinander verbunden sein, vorzugsweise durch adhäsive Verklebung, Verschmelzung, Zusammenhalten durch Rahmen oder Haltekonstruktionen von festen Werkstoffen, Aufschäumen von plastischen, elastischen oder starren aufschäumbaren Werkstoffen, Aufsprühen oder Auftragen von flüssigen oder plastisch formbaren Werkstoffen.Furthermore, the different absorption layers can be connected to one another at points or surfaces, preferably by adhesive bonding, fusion, holding together by frames or holding structures of solid materials, foaming of plastic, elastic or rigid foamable materials, spraying or application of liquid or plastically moldable materials.
Beispielsweise ist die einer Schallquelle zuzuwendende Absorptionsschicht verhältnismäßig höher verdichtete und/oder steifere Schicht perforiert oder geschlitzt. Die Veränderung der Dicke der der Schallquelle abgewandten Schicht, d.h. ihrer Ausgestaltung in unterschiedlicher Dicke, beeinflusst insbesondere die Reichweite der Absorptionswirkung in den tieffrequenten Bereich hinein, insbesondere nach Art eines Folien- oder Plattenresonanzabsorbers oder Membranabsorbers.For example, the absorbing layer facing a sound source is perforated or slit in a relatively higher density and / or stiffer layer. The change in the thickness of the layer facing away from the sound source, i. their configuration in different thickness, in particular affects the range of the absorption effect in the low-frequency range, in particular in the manner of a film or plate resonant absorber or membrane absorber.
Insbesondere werden zwei oder mehr Absorptionsschichten kombiniert, d. h in Reihen montiert und geschaltet, wobei durch die Dichte der zweiten, dritten oder jeder fortfolgenden der Schallquelle zugewandten höher verdichten Schicht eine negative Beeinflussung der Absorptionswirkung durch störende Reflexionen innerhalb des Gesamtaufbaus vermieden sind. Die Verbindung erfolgt z.B. durch punktuelle oder flächige Adhäsivverklebung, Verschmelzung, Zusammenhalten durch Rahmen oder Haltekonstruktionen von festen Werkstoffen, Aufschäumen von plastischen, elastischen oder starren aufschäumbaren Werkstoffen, Aufsprühen oder Auftragen von flüssigen oder plastisch formbaren Werkstoffen. Durch die Veränderung der Dicke der weniger verdichteten und weniger versteiften Schicht bzw. des weniger verdichteten oder versteiften Bereiches, kann nach der Art eines Platten-, Membran- oder Folienresonators der Wirkungsgrad im tieffrequenten Bereich eingestellt werden. Durch die offenporig poröse Eigenschaft der dünneren der Schallquelle zugewandten höher verdichteten und/oder höher versteiften Schicht wird jedoch das Durchdringen dieser Schicht durch die Schallwellen ermöglicht, so dass eine optimale Absorbtion auch im höherfrequenten Bereich erzielt wird. Überraschenderweise ermöglicht die Kombination derartiger Absorptionsschichten eine deutlich breitbandigere Absorptionswirkung als bekannte Absorber, insbesondere herkömmliche Platten-, Folien- oder Membranabsorber, jedoch auch einen hohen Absorptionsgrad im tieffrequenten Bereich gleich der Wirkungsweise von herkömmlichen Platten-, Folien- oder Membranabsorbern.In particular, two or more absorption layers are combined, i. h mounted and connected in rows, wherein the density of the second, third or each successive the sound source facing higher density layer a negative influence on the absorption effect by disturbing reflections within the overall structure are avoided. The connection is made, for example, by spot or surface adhesive bonding, fusion, holding together by means of frames or holding structures of solid materials, foaming of plastic, elastic or rigid foamable materials, spraying or application of liquid or plastically moldable materials. By changing the thickness of the less compacted and less stiffened layer or the less compacted or stiffened region, the efficiency in the low-frequency range can be adjusted in the manner of a plate, membrane or film resonator. Due to the open porous property of the thinner sound source facing higher densified and / or higher stiffened layer, however, the penetration of this layer is made possible by the sound waves, so that an optimal absorption is achieved in the higher frequency range. Surprisingly, the combination of such absorption layers allows a significantly broader band absorption effect than known absorbers, in particular conventional plate, film or membrane absorbers, but also a high absorption in the low-frequency range equal to the mode of action of conventional plate, film or membrane absorbers.
Durch die offenporig porösen Eigenschaften der jeweils höher verdichteten und höher versteiften Schicht wird eine Verminderung der Erhöhung durch der Absorptionswirkung entgegen wirkende Reflexionen innerhalb des Absorberaufbaus vermieden. Bei der Verbindung und/oder dem Anschluss eines mechanischen Schwingungserregers an die höher verdichtete und/oder versteifte Schicht oder damit verbundene Rahmen- oder Haltekonstruktionen entsteht z.B. zudem der Effekt, dass der Absorber zum breitbandigen Luftschallabstrahler wird.Due to the open-pored porous properties of each higher-density and higher stiffened layer, a reduction in the increase by the absorption effect counteracting reflections within the absorber structure is avoided. Upon connection and / or connection of a mechanical vibration exciter to the higher density and / or stiffened layer or frame or support constructions connected thereto, e.g. In addition, the effect that the absorber is the broadband airborne sound radiator.
Des Weiteren kann der erfindungsgemäße Absorber auch mindestens eine Schallabsorptionsschicht aufweisen, die nicht aus einem offenporig porösen Fasermaterial (sondern z.B. aus einem Schaumstoff) gebildet ist. Auch ist denkbar, dass die Absorptionsschicht auf einem insbesondere elastischen Träger (z.B. einer Trägerplatte) angeordnet ist, wobei der Träger insbesondere aus einem porösen Material gebildet ist. Durch die Ankopplung der Absorptionsschicht an den Träger können Schwingungen der Absorptionsschicht Matrixschwingungen (Kompressionswellen und Scherwellen) innerhalb des Trägers, z.B. innerhalb der Skelettstruktur eines Trägers aus einem porösen Material, angeregt werden. Des Weiteren können je nach Ausgestaltung des Trägers auch kolbenförmige und/oder Biegeschwingungen im Träger angeregt werden, so dass die Ausgestaltung (z.B. Material, Abmessungen, Art der Befestigung, Art der Haftung) des Trägers im Hinblick auf eine Abstimmungsoptimierung der Absorption- und/oder Schalldämmungseigenschaften des erfindungsgemäßen akustischen Absorbers erfolgen kann.Furthermore, the absorber according to the invention can also have at least one sound absorption layer, which is not formed from an open-pore porous fiber material (but for example from a foam). It is also conceivable that the absorption layer is arranged on a particularly elastic carrier (eg a carrier plate), wherein the carrier is formed in particular from a porous material. By coupling the absorption layer to the support, vibrations of the absorption layer can be excited by matrix vibrations (compression waves and shear waves) within the support, for example within the skeletal structure of a carrier made of a porous material. Furthermore, depending on the design of the carrier, piston-shaped and / or bending oscillations in the carrier can also be excited, so that the design (eg material, dimensions, type of attachment, type of adhesion) of the carrier with regard to a tuning optimization of the absorption and / or Sound insulation properties of the acoustic absorber according to the invention can be carried out.
Der erfindungsgemäße Absorber kann auch eine (oder mehrere) weitere luftdurchlässige Schicht aufweisen (z.B. eine perforierte Fläche oder eine Gitterstruktur) und/oder eine (oder mehrere) weitere luftumschließende oder luftundurchlässige Schicht (z.B. eine Folie). Die weitere luftundurchlässige Schicht (z.B. aus Stahl) kann z.B. mit der Absorptionsschicht gekoppelt (verbunden) sein, um einen Schichtverbund mit erhöhter Biegesteifigkeit zu erzeugen. Die weiteren Schichten können zumindest näherungsweise die Flächenabmessungen der Absorptionsschicht aufweisen. Es ist jedoch auch denkbar, dass zumindest einige der weiteren Schichten (bezogen auf die Fläche) kleiner sind als die Absorptionsschicht und/oder eine andere Geometrie aufweisen.The absorber of the present invention may also include one (or more) further air-permeable layer (e.g., a perforated surface or lattice structure) and / or one (or more) other air-enclosing or air-impermeable layers (e.g., a film). The further air-impermeable layer (e.g., steel) may e.g. be coupled (connected) to the absorption layer to produce a layer composite with increased bending stiffness. The further layers can at least approximately have the area dimensions of the absorption layer. However, it is also conceivable that at least some of the further layers (relative to the surface) are smaller than the absorption layer and / or have a different geometry.
Gemäß einer weiteren Ausführungsform des Absorbers weist die Absorptionsschicht einen ersten Abschnitt auf, der relativ gegenüber einem zweiten Abschnitt bewegbar ist, so dass z.B. eine Faltung der Schicht möglich ist. Insbesondere kann die Absorptionsschicht auch mehr als ein (z.B. längliches oder punktartiges) Gelenk aufweisen, so dass die Absorptionsschicht z.B. ziehharmonikaartig mit gleichmäßigen oder unterschiedlichen Abständen der Faltung auseinandergezogen und zusammengestaucht werden kann. Insbesondere kann die Absorptionsschicht über ein längliches Gelenk (oder die mehreren Gelenke) entlang einer Linie, die parallel zu einem Seitenrand der Absorptionsschicht verläuft, gefaltet werden. Ein punktförmiges Gelenk ermöglicht ein scherenartiges Auffächern der Absorptionsschicht.According to a further embodiment of the absorber, the absorption layer has a first portion which is movable relative to a second portion, so that e.g. a folding of the layer is possible. In particular, the absorbent layer may also have more than one (e.g., elongate or pointy) hinge, such that the absorbent layer is e.g. accordion-like with uniform or different intervals of the folding can be pulled apart and compressed. In particular, the absorbent layer may be folded over an elongate hinge (or joints) along a line parallel to a side edge of the absorbent layer. A punctiform joint allows a scissor-like fanning of the absorption layer.
Durch Falten und/oder Auffächern der Absorptionsschicht ist es insbesondere möglich, den effektiven Strömungswiderstand der Absorptionsschicht einzustellen, so dass sich für den Strömungswiderstand der Absorptionsschicht in Abhängigkeit von ihrer Dicke d, der Massendichte ρ0 und der Schallgeschwindigkeit in Luft c o für den Strömungswiderstand Ξ ergibt:
Hierbei ist X ein Faktor, der die Höhe des spezifischen Strömungswiderstands definiert:
Bei der Verwendung von homogenen porösen Absorbern, müsste die Höhe des Strömungswiderstands, bzw, der Faktor X, im Herstellungsprozess auf die jeweilige Dicke angepasst werden. Die obige Variante der Erfindung ermöglicht es, die Einstellung des Faktors X über das Auffächern der Absorptionsschicht einzustellen.When using homogeneous porous absorbers, the height of the flow resistance, or factor X, would have to be adapted to the respective thickness in the manufacturing process. The above variant of the invention makes it possible to adjust the setting of the factor X over the fanning of the absorption layer.
Gemäß einer weiteren Variante der Erfindung ist der Rand der Absorptionsschicht zumindest abschnittsweise in einem Rahmen gelagert. Insbesondere kann der Rand in dem Rahmen so festgelegt sein, dass der Randbereich (oder zumindest Abschnitte des Randbereichs) der Absorptionsschicht zumindest im Wesentlichen nicht zu Schwingungen angeregt werden kann. Der "Rand" der Absorptionsschicht begrenzt die Absorptionsschicht in einer Richtung senkrecht zu ihrer Dickenrichtung. Allerdings ist die Lagerung der Absorptionsschicht in einem Rahmen nicht zwingend, wie bereits weiter oben angesprochen.According to a further variant of the invention, the edge of the absorption layer is at least partially stored in a frame. In particular, the edge in the frame can be set so that the edge region (or at least portions of the edge region) of the absorption layer can at least substantially not be excited to vibrate. The "edge" of the absorption layer bounds the absorption layer in a direction perpendicular to its thickness direction. However, the storage of the absorption layer in a frame is not mandatory, as already mentioned above.
Die Erfindung betrifft auch ein Verfahren zum Herstellen eines akustischen Absorbers oder Wandlers, mit den Schritten:
- Bereitstellen einer Materialschicht, die aus mehreren Vlieslagen besteht;
- Verdichten und/oder Aufschäumen der Materialschicht, bis diese derart biegesteif ist, dass sie bei Auftreffen von Schallwellen zu Biegeschwingungen angeregt wird; und
- Binden der Vlieslagen und/oder der Fasern der Vlieslagen mit einem Bindemittel in Form von Latex und/oder mit einem thermisch aktivierbaren Bindemittel.
- Providing a layer of material consisting of a plurality of nonwoven layers;
- Compacting and / or foaming the material layer until it is so rigid that it is excited upon impact of sound waves to bending vibrations; and
- Bonding the nonwoven layers and / or the fibers of the nonwoven layers with a binder in the form of latex and / or with a thermally activatable binder.
Insbesondere wird die Materialschicht als "Absorptionsschicht" in dem oben beschriebenen erfindungsgemäßen akustischen Absorber verwendet. Entsprechend kann die Materialschicht verdichtet oder aufgeschäumt werden, bis sie eine Biegesteifigkeit von 10 bis 100 Nm2, insbesondere zwischen 10 und 30 Nm2 beisitzt, In einem anderen Beispiel wird die Schicht soweit verdichtet bzw. aufgeschäumt, dass ihre tiefste Eigenfrequenz bezüglich Biegeschwingungen unterhalb von 300 Hz liegt.In particular, the material layer is used as the "absorption layer" in the above-described acoustic absorber of the present invention. Accordingly, the material layer can be compressed or foamed until it has a bending stiffness of 10 to 100 Nm 2 , in particular between 10 and 30 Nm 2 , in another example, the layer is densified or foamed so far that their lowest natural frequency with respect to bending vibrations below 300 Hz.
Die Materialschicht weist, insbesondere, um möglichst gleichmäßige Porengrößen (Hohlraumgrößen, der zwischen den Fasern des Vlieses gebildeten Hohlräume) zu erzielen, mehrlagige Faservliese auf, insbesondere aus hoch flexiblen organischen Fasern, beispielsweise aus organischen Synthesefasern wie Polypropylen, Viskose, Polyacrylnitril, Polyamide oder Polyester.The material layer has, in particular in order to achieve the most uniform pore sizes possible (cavity sizes, the voids formed between the fibers of the web) multilayer fiber webs, in particular of highly flexible organic fibers, for example of organic synthetic fibers such as polypropylene, viscose, polyacrylonitrile, polyamides or polyester ,
Gemäß einer Variante des erfindungsgemäßen Verfahrens erfolgt das Verdichten der aus mehreren Vlieslagen gebildeten Materialschicht durch Nadeln und/oder Pressen. Beispielsweise wird die Materialschicht zunächst mehrfach mit Nadeln senkrecht zur Vliesebene ober- und/oder unterseitig genadelt Es ist jedoch alternativ oder zusätzlich auch möglich, dass die Vlieslagen der Materialschicht auf andere Weise miteinander verbunden und/oder vorverfestigt werden.According to a variant of the method according to the invention, the compacting of the material layer formed by a plurality of nonwoven layers is accomplished by needling and / or pressing. For example, the material layer However, it is alternatively or additionally also possible for the nonwoven layers of the material layer to be connected to one another and / or preconsolidated in another way.
Des Weiteren wird zur Bindung der Vlieslagen und/oder der Fasern der Vlieslagen bzw. zur Vorverdichtung (vor einem anschließenden Pressen) der einzelnen Lagen ein Bindemittel in Form von Latex und/oder in Form eines thermisch aktivierbaren Bindemittels, z.B. in Form von Bikomponenten-Fasem, verwendet.Furthermore, to bind the nonwoven layers and / or the fibers of the nonwoven layers or for pre-compaction (before a subsequent pressing) of the individual layers, a binder in the form of latex and / or in the form of a thermally activatable binder, e.g. in the form of bicomponent fibers.
Zur Endversteifung kann die Vlies-Materialschicht über eine Presse auf die gewünschte Steifigkeit verpresst uns auf diese Weise verdichtet werden. Nach der Verpressung kann die Materialschicht noch einmal genadelt und nach dieser erneuten Nadelung noch einmal verpresst werden. Selbstverständlich können die Schritte Nadeln/Verpressen der Materialschicht so oft wie für die gewünschte Biegesteifigkeit und/oder Luftdurchlässigkeit der Materialschicht notwendig wiederholt werden. Durch dieses Verfahren lässt sich z.B. eine Vlies-Materialschicht mit einer Biegesteifigkeit erzeugen, die z.B. der Biegesteifigkeit einer Holzplatte (z.B. aus Birkenholz oder Eichenholz), einer Holzwerkstoffplatte oder einer Plexiglasplatte mit vergleichbaren (insbesondere identischen) Abmessungen entspricht oder diese übertrifft.For final stiffening, the nonwoven material layer can be compressed by means of a press to the desired stiffness and compressed in this way. After pressing, the material layer can be needled again and pressed again after this re-needling. Of course, the steps of needling / crimping the material layer may be repeated as often as necessary for the desired flexural rigidity and / or air permeability of the material layer. By this method, e.g. produce a nonwoven material layer having a flexural rigidity, e.g. the flexural rigidity of a wooden panel (e.g., birch or oak), a wood-based panel, or a plexiglass panel of comparable (especially identical) dimensions is equal to or better than that.
Insbesondere beim Nadeln einer bereits vorverdichteten Materialschicht wird eine Vorschubgeschwindigkeit, d.h. die Geschwindigkeit, mit der die Materialschicht durch eine Nadelungsvorrichtung geführt wird, gewählt, die deutlich geringer ist als die Vorschubgeschwindigkeiten, die beim Nadeln eines konventionellen Vlieses verwendet werden. Insbesondere wird eine Vorschubgeschwindigkeit im Bereich von 0,50m/Minute bis 3 m/Minute, insbesondere zwischen 0,5 m/Minute und 2 m/Minute benutzt.In particular, when needling an already precompacted material layer, a feed rate, i. the speed at which the material layer is passed through a needle device, which is significantly lower than the feed rates used in the needling of a conventional nonwoven fabric. In particular, a feed rate in the range of 0.50 m / minute to 3 m / minute, in particular between 0.5 m / minute and 2 m / minute is used.
Insbesondere kann das Nadeln der Materialschicht nach dem Verpressen dazu dienen, eine Perforation (insbesondere eine Mikroperforation) oder eine Teilperforation in der verdichteten Materialschicht zu erzeugen, d.h. die Zahl der miteinander verbundenen Hohlräume zwischen den Fasern der Schicht zu erhöhen, um den Strömungswiderstand der Materialschicht zu reduzieren. Es ist auch denkbar, dass anstelle eines Nadelns eine Perforation oder eine Teilperforation der Materialschicht durch andere mechanische Verfahren (z.B. Bohren, Perforieren per Wasserstrahl) und/oder thermische Verfahren (z.B. heiße Nadelung, Laserperforation) vorgenommen wird.In particular, the needling of the material layer after compression may serve to create a perforation (in particular a microperforation) or a partial perforation in the densified material layer, i. to increase the number of interconnected voids between the fibers of the layer to reduce the flow resistance of the material layer. It is also conceivable that, instead of needling, perforation or partial perforation of the material layer may be accomplished by other mechanical methods (e.g., drilling, water jet perforation) and / or thermal methods (e.g., hot needling, laser perforation).
Schließlich lässt sich auch die Elastizität der Materialschicht z.B. durch Nadeln und/oder Kalandrieren verändern (insbesondere steigern). Es wird darauf hingewiesen, dass alsFinally, the elasticity of the material layer can also be changed (in particular increase) by needling and / or calendering, for example. It should be noted that as
Material der Materialschicht insbesondere Vliese verwendet werden, die eine hohe Bruchfestigkeit aufweisen, so dass in der Matehalschicht auch Biegeschwingungen hoher Amplitude anregbar sind, ohne die Materialschicht zu beschädigen. Beispielsweise werden Vliese verwendet, deren Fasern eine geeignete Länge aufweisen (z.B. mindestens 40 mm) und die hinreichend elastisch und bruchfest sind.Material of the material layer can be used in particular nonwovens, which have a high breaking strength, so that bending vibrations of high amplitude can be excited in the Matehalschicht without damaging the material layer. For example, nonwovens are used whose fibers have a suitable length (e.g., at least 40 mm) and which are sufficiently elastic and break-resistant.
Wie oben bereits im Zusammenhang mit der Absorptionsschicht erwähnt, kann die Materialschicht insbesondere unterschiedliche Faserarten aufweisen und/oder Vliesschichten, die aus unterschiedlichen Faserarten gebildet sind. Beispielsweise können einem Ausgangsmaterial einer ersten Faserart Faser einer zweiten Faserart (z.B. einer von der ersten Faserart verschiedenen Viskosität) beigemischt werden.As already mentioned above in connection with the absorption layer, the material layer can in particular have different types of fibers and / or nonwoven layers which are formed from different types of fibers. For example, a fiber of a second type of fiber (e.g., a viscosity different from the first type of fiber) can be blended into a starting material of a first type of fiber.
Darüber hinaus ist auch denkbar, dass zusätzlich (oder anstelle unterschiedlich viskoser Faserarten) ein anderes viskoses Material beigefügt wird, das eine höhere Viskosität als die Fasern der Vliesmaterialschicht besitzt, insbesondere, um die Rückstellelastizität der Materialschicht bei Biegebeanspruchung zu beeinflussen. Beispielsweise kann hierdurch eine stärkere Energieaufnahme und Dämpfung von Schwingungen der Materialschicht erreicht werden, d.h. die Rückstellung bei einer biegeelastischen Beanspruchung der Materialschicht erfolgt mit einer erhöhten Trägheit, so dass den Schwingungen der Materialschicht und damit einem auf die Materialschicht einwirkenden Schallfeld mehr Energie entzogen wird.Moreover, it is also conceivable that in addition (or instead of different viscous fiber types) another viscous material is added, which has a higher viscosity than the fibers of the nonwoven material layer, in particular to influence the resilience of the material layer under bending stress. For example, this can achieve greater energy absorption and damping of vibrations of the material layer, i. the provision for a flexurally elastic stress of the material layer is carried out with an increased inertia, so that the vibrations of the material layer and thus a sound field acting on the material layer more energy is withdrawn.
Es ist auch möglich, dass die verdichtete Materialschicht thermoplastisch verformt wird, um sie in eine für einen akustischen Absorber gewünschte Form zu bringen. Auch können die Fasern eines zur Herstellung der Materialschicht verwendeten Vlieses eine Beschichtung aufweisen oder im Rahmen der Herstellung der Materialschicht mit einer Beschichtung versehen werden. Beispielsweise kann es sich um eine schmutzabweisende Beschichtung der Fasern handeln und/oder eine Beschichtung zur Farbgebung, zum Flammschutz, Geruchshemmung, Erhöhung der Hydrolysebeständigkeit, UV-Schutz, Schmutzabweisung, Wasserabweisung der Fasern, wobei z.B. eine plasmapolymere Funktionsbeschichtung, eine Teflonbeschichtung und/oder eine Nanobeschichtung in Frage kommt.It is also possible that the densified material layer is thermoformed to bring it into a desired shape for an acoustic absorber. The fibers of a nonwoven used to produce the material layer may also have a coating or be provided with a coating during the production of the material layer. For example, it may be a soil-repellent coating of the fibers and / or a coating for coloring, flame retardance, odor control, increase in hydrolysis resistance, UV protection, soil repellency, water repellency of the fibers, e.g. a plasma polymer functional coating, a Teflon coating and / or a nanocoating comes into question.
Darüber hinaus wird darauf hingewiesen, dass beim Herstellen der Materialschicht entstehende Reste der verwendeten Vliesmaterialien recycelt werden und wiederum als Ausgangsmaterial zur Herstellung einer weiteren Materialschicht dienen können. Hierfür werden die Abfälle z.B. geschreddert und anschließend nach dem oben beschriebenen Verfahren zur Herstellung der Materialschicht verarbeitet.In addition, it is pointed out that residues of the nonwoven materials used during the production of the material layer can be recycled and, in turn, serve as starting material for producing a further material layer. Therefor For example, the waste is shredded and then processed according to the method described above for producing the material layer.
Beispielsweise weist die Absorptionsschicht offenporige Schäume, Fasermaterialien, Mineralstoffe, Glaswerkstoffe, Keramiken, Kunststoffe, aber auch feste Materialien wie Porenbeton oder Ähnliches auf. Der Begriff "Glas" erfasst Glas an sich und auch alle glasverwandten Baustoffe, wie Plexiglas, Acrylglas, organische Glas, wie Kristallglas.For example, the absorption layer has open-cell foams, fiber materials, minerals, glass materials, ceramics, plastics, but also solid materials such as cellular concrete or the like. The term "glass" covers glass itself and also all glass-related building materials, such as Plexiglas, acrylic glass, organic glass, such as crystal glass.
Ein "Kunststoff" ist zum Beispiel PVC, Polyethylen, Polypropylen, Polyester, Polysterol einschließlich Polysterol mit Glasfaser, Gummi, Kautschuk einschließlich Naturkautschuk, insbesondere Schäume aus Kunststoffen sowie Kunststofffolien aus den vorgenannten Materialien. Die Absorptionsschicht kann jedoch auch auch Metall wie Aluminium, Blei, Kupfer, Messing, Eisen, Stahl einschließlich der Veredelungsformen wie Edelstahl sowie Stahllegierungen und Stahlguss, Temperguss, Sintermetalle wie Zink, Zinn, Gold und Platin aufweisen.A "plastic" is, for example, PVC, polyethylene, polypropylene, polyester, polystyrene, including polystyrene with glass fiber, rubber, rubber including natural rubber, in particular foams of plastics and plastic films of the aforementioned materials. However, the absorption layer may also include metal such as aluminum, lead, copper, brass, iron, steel including finishings such as stainless steel and steel alloys and cast steel, malleable cast iron, sintered metals such as zinc, tin, gold and platinum.
Die Erfindung wird im Folgenden anhand von Ausführungsbeispielen unter Bezugnahme auf die Figuren näher erläutert. Es zeigen:
- Figur 1A bis 1G
- verschiedene Varianten des erfindungsgemäßen akustischen Absorbers;
- Figuren 2A bis 2D
- weitere Varianten des erfindungsgemäßen akustischen Absorbers;
- Figuren 3A und 3B
- weitere Ausführungsbeispiele des erfindungsgemäßen akustischen Absorbers;
- Figuren 4A und 4B
- unterschiedliche Möglichkeiten der Lagerung der Absorptionsschicht des erfindungsgemäßen akustischen Absorbers;
- Figuren 5A bis 5D
- weitere Ausführungsformen des erfindungsgemäßen akustischen Absorbers;
- Figuren 6A bis 6C
- akustische Absorber gemäß weiterer Ausführungsbeispiele der Erfindung;
Figur 7- Diagramm zum Schallabsorptionsverhalten der Luft;
Figur 8- Diagramm zum Absorptionsverhalten unterschiedlicher offenporig poröser Materialien;
Figur 9- eine weitere Ausführungsform des erfindungsgemäßen akustischen Absorbers;
- Figuren 10A bis 10D
- Varianten eines erfindungsgemäßen akustischen Absorbers mit perforierter Absorptionsschicht;
Figur 11- eine weitere Ausführungsform des erfindungsgemäßen akustischen Absorbers;
- Figuren 12A bis 12E
- weiteren Ausführungsbeispiele des erfindungsgemäßen akustischen Absorbers;
- Figuren 13A bis 13C
- Varianten der Absorptionsschicht des erfindungsgemäßen akustischen Absorbers;
Figur 14- ein weiteres Ausführungsbeispiel des erfindungsgemäßen akustischen Absorbers; und
Figur 15- bewegbares Element des erfindungsgemäßen akustischen Wandlers.
- FIGS. 1A to 1G
- different variants of the acoustic absorber according to the invention;
- FIGS. 2A to 2D
- further variants of the acoustic absorber according to the invention;
- FIGS. 3A and 3B
- further embodiments of the acoustic absorber according to the invention;
- FIGS. 4A and 4B
- different possibilities of storage of the absorption layer of the acoustic absorber according to the invention;
- FIGS. 5A to 5D
- further embodiments of the acoustic absorber according to the invention;
- FIGS. 6A to 6C
- acoustic absorbers according to further embodiments of the invention;
- FIG. 7
- Diagram of the sound absorption behavior of the air;
- FIG. 8
- Diagram of the absorption behavior of different open porous materials;
- FIG. 9
- a further embodiment of the acoustic absorber according to the invention;
- FIGS. 10A to 10D
- Variants of an acoustic absorber according to the invention with a perforated absorption layer;
- FIG. 11
- a further embodiment of the acoustic absorber according to the invention;
- FIGS. 12A to 12E
- further embodiments of the acoustic absorber according to the invention;
- FIGS. 13A to 13C
- Variants of the absorption layer of the acoustic absorber according to the invention;
- FIG. 14
- a further embodiment of the acoustic absorber according to the invention; and
- FIG. 15
- movable element of the acoustic transducer according to the invention.
Die
Im Beispiel der
Andere Möglichkeiten der Ausgestaltung der Absorptionsschicht 1 zeigen die
Des Weiteren ist es auch möglich, dass die Absorptionsschicht 1 einen (z.B. im Querschnitt rechteckigen) Grundkörper 13 aufweist, von dem (z.B. periodisch angeordnete) im Querschnitt rechteckige (
Selbstverständlich können die Varianten der
Die
Anstelle oder zusätzlich zu einem rückwärtigen Luftpolster können jedoch auch andere elastische Elemente mit der Absorptionsschicht des Absorbers gekoppelt werden. Dies ist in den
Eine andere Möglichkeit der federnden Lagerung der Absorptionsschicht 1 zeigt die
Gemäß den Varianten 5A bis D ist auf der eigentlichen Absorptionsschicht 1 ein Masseelement 4 aufgebracht, das insbesondere aus einem anderen Material gebildet ist als die Absorptionsschicht. Das Masseelement dient insbesondere zur Abstimmung der Eigenfrequenzen der Absorptionsschicht 1. Das Masseelement kann eine im Prinzip beliebige Geometrien aufweisen, z.B. gitterartig (gemäß der Schnittansicht der
Die
Der erfindungsgemäße Absorber kann auch andere Mittel zur Erzeugung einer Rückstellkraft auf die Absorptionsschicht aufweisen, insbesondere können die Seitenwände des Rahmens elastisch ausgebildet sein. Es ist auch möglich, dass die Absorptionsschicht 1 mit elastischen Elementen z.B in Form einer Feder 3 oder einer elastischen Wand 31 gekoppelt ist, die eine Schwingung der Absorptionsschicht aufnehmen. Insbesondere sind die elastischen Elemente im Bereich ihres Seitenrandes 14 mit der Absorptionsschicht gekoppelt, z.B. sind zwei elastische Elemente vorgesehen, die an einander gegenüberliegenden Seitenrandabschnitten der Absorptionsschicht mit dieser gekoppelt sind; vgl.
Zum weiteren Vergleich ist auch das Absorptionsverhalten eines Plattenresonators (Dreiecke) dargestellt, der nahezu ausschließlich aufgrund angeregter Biegeschwingungen absorbiert, d.h. nahezu ausschließlich im niederfrequenten Schallbereich, während die Absorptionsschicht des erfindungsgemäßen Absorbers sowohl im niederfrequenten als auch im höherfrequenten Bereich absorbiert.For further comparison, the absorption behavior of a plate resonator (triangles) is shown, which absorbs almost exclusively due to excited bending vibrations, i. almost exclusively in the low-frequency sound range, while the absorption layer of the absorber according to the invention absorbs both in the low-frequency and in the higher-frequency range.
Um das Absorptionsverhalten der Absorptionsschicht weiter abzustimmen, kann sie eine Perforation aufweisen; vgl.
Gemäß dem Ausführungsbeispiel der
Die Ausführungsbeispiele der
Darüber hinaus kann in dem Volumen 5 ein Dämmmaterial 7 angeordnet sein, insbesondere derart, dass das Volumen zumindest näherungsweise komplett gefüllt ist (
Auch wenn der erfindungsgemäße Absorber nur eine Absorptionsschicht aufweist, kann diese an ihrer Rückseite ein Dämmmaterial aufweisen (
Eine weitere Ausführungsform des erfindungsgemäßen Absorbers zeigt
Es wird darauf hingewiesen, dass Elemente der oben erläuterten Ausführungsbeispiele natürlich auch miteinander kombiniert werden können. Beispielsweise kann das bewegbare Element der
Claims (13)
- An acoustic absorber, comprising an absorption layer (1) formed from an open-pore porous material, wherein the open-pore porous material is formed flexurally elastically in such a way that flexural vibrations with natural frequency of the absorption layer (1) are excited in the absorption layer (1) when sound waves strike it and, owing to the inflow of air into the open-pore porous material of the absorption layer, the absorber can absorb sound waves in a first frequency range and, on account of the excitation of flexural vibrations of the absorption layer, sound waves in a second frequency range, which comprises lower frequencies than the first frequency range,
characterized in that
the open-pore porous material consists of a plurality of nonwoven layers and comprises a binder in the form of latex and/or a thermally activatable binder that bonds the nonwoven layers and/or the fibers of the nonwoven layers. - The acoustic absorber as claimed in claim 1, characterized in that the open-pore porous material is viscous such that flexural vibrations of the absorption layer (1) are damped.
- The acoustic absorber as claimed in claim 1 or 2, characterized in that the absorption layer (1) has a flexural stiffness in the range between 200 and 400 Nm.
- The acoustic absorber as claimed in one of the preceding claims, characterized in that the lowest flexural-vibration natural frequency of the absorption layer is in the range between 0.00005 Hz and 300 Hz.
- The acoustic absorber as claimed in one of the preceding claims, characterized in that the mass per unit area varies in the thickness direction of the absorption layer (1) and/or in a direction that is perpendicular to the thickness direction.
- The acoustic absorber as claimed in one of the preceding claims, characterized in that the absorption layer is supported such that piston-type vibrations can be excited therein.
- The acoustic absorber as claimed in one of the preceding claims, characterized in that the open-pore porous material has first fibers of a first material and second fibers of a second material.
- The acoustic absorber as claimed in claim 7, characterized in that the first fibers have a higher viscosity than the second fibers.
- The acoustic absorber as claimed in one of the preceding claims, characterized in that the absorption layer formed by the open-pore porous material represents a first absorption layer (1a) of the absorber and the absorber has a second absorption layer (1b) which is likewise formed from an open-pore porous material.
- The acoustic absorber as claimed in one of the preceding claims, characterized in that the acoustic absorber is exclusively formed by a plate-like absorption layer.
- The acoustic absorber as claimed in one of the preceding claims and a frame, wherein the absorption layer is inserted loosely in the frame or is at least partially clamped in the frame.
- Use of an acoustic absorber as claimed in one of the claims 1 to 10, wherein the acoustic absorber is at least partially supported in such a manner that it can vibrate freely.
- A method for producing an acoustic absorber comprising the following steps:- providing a material layer which consists of a plurality of nonwoven layers;- densifying or foaming the material layer such that an open-pore porous absorption layer results which is flexurally elastically in such a way that it is excited to flexurally vibrations with natural frequency of the absorption layer (1) when sound waves impinge and owing to the inflow of air into the open-pore porous material of the absorption layer, the absorber can absorb sound waves in a first frequency range and, on account of the excitation of flexural vibrations of the absorption layer, sound waves in a second frequency range, which comprises lower frequencies than the first frequency range,
characterized by
bonding the nonwoven layers and/or the fibers of the nonwoven layers with a binder in the form of latex and/or a thermally activatable binder.
Applications Claiming Priority (2)
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DE102009007891A DE102009007891A1 (en) | 2009-02-07 | 2009-02-07 | Resonance sound absorber in multilayer design |
PCT/EP2010/051520 WO2010089398A2 (en) | 2009-02-07 | 2010-02-08 | Acoustic absorber, acoustic transducer, and method for producing an acoustic absorber or an acoustic transducer |
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EP (1) | EP2394265B1 (en) |
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CN102362309A (en) | 2012-02-22 |
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WO2010089398A3 (en) | 2011-03-03 |
US9369805B2 (en) | 2016-06-14 |
US20120155688A1 (en) | 2012-06-21 |
WO2010089398A2 (en) | 2010-08-12 |
EP2394265A2 (en) | 2011-12-14 |
AU2010210069B2 (en) | 2015-05-07 |
DE102009007891A1 (en) | 2010-08-12 |
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