acoustic component

Abstract

In one aspect, the present application relates to an acoustic component comprising acoustic damping material based on mineral wool and / or glass wool, wherein this acoustic component includes at least one Helmholtz resonator. In another aspect, the present application relates to a method for manufacturing an acoustic component according to the invention, comprising providing the acoustic damping material based on mineral wool and / or glass wool and incorporating at least one Helmholtz resonator into the acoustic damping material. Finally, a kit is described comprising acoustic damping material based on mineral wool and / or glass wool and at least one Helmholtz resonator, suitable for manufacturing an acoustic component according to the invention. Finally, the use of an acoustic component according to the invention or a corresponding kit for acoustic absorption, in particular for acoustic absorption in selected frequency ranges, is described.In particular, the acoustic components according to the invention are suitable for use in the vehicle sector.

Description

[0001] In one aspect, the present application relates to an acoustic component comprising acoustic damping based on mineral wool and / or glass wool, wherein this acoustic component has at least one Helmholtz resonator. In a further aspect, the present application is directed to a method for producing an acoustic component according to the invention, comprising providing the acoustic damping based on mineral wool and / or glass wool and introducing at least one Helmholtz resonator into the acoustic damping. Finally, a kit is described, comprising acoustic damping based on mineral wool or glass wool and at least one Helmholtz resonator, suitable for producing an acoustic component according to the invention. Finally, the use of an acoustic component according to the invention or a corresponding kit for acoustic absorption, in particular for acoustic absorption in selected frequency ranges, is described.The acoustic components according to the invention are particularly suitable for use in the automotive sector. State of the art

[0002] Reducing resonance effects plays a key role in acoustic development in many areas. In the automotive sector, among others, a wide variety of absorbers are used to achieve appropriate noise reduction. Common absorbers are porous absorbers that allow broadband absorption. Foams, such as open-cell polyurethane foams, or fibers, such as glass or mineral fibers, are used as absorption materials. These fibers, due to their porosity, offer good acoustic absorption properties. To reduce acoustic resonance effects, shift resonant frequencies to lower frequencies, or dampen their amplitudes, mass loading or stiffness adjustment is usually performed, which often entails an increase in weight.

[0003] The acoustic absorption components used in the automotive industry, for example in the field of exhaust technology, usually have additional thermal insulation properties.

[0004] Porous absorption materials, such as the fibers mentioned, demonstrate good broadband absorption performance, particularly in the higher frequency range (approximately above 1-2 kHz). Especially in the low frequency range below 1500 Hz, high absorption performance without adding mass is difficult to achieve given a low thickness / component strength. A further problem with absorption materials is that they can only be manufactured to a limited extent for narrow frequency ranges with the correspondingly necessary absorption properties for these narrow frequency ranges. Especially in the automotive industry, but also in other sectors, sound radiation frequently occurs in narrow frequency ranges, e.g., as the resonant frequency of components, which must be suppressed using complex acoustic measures.

[0005] The use of resonators in the absorption range is well known. In acoustics, resonance absorbers serve as noise protection, and in room acoustics, resonators allow the absorption of narrowband, often low-frequency room modes. For example, resonators are used in acoustic ceilings. One example of suitable resonance absorbers are Helmholtz resonators, which, like many resonance absorbers, essentially consist of a mass and a spring. The resulting sound energy is converted into kinetic energy of the vibrating mass to achieve appropriate absorption. Typically, maximum absorption occurs at the frequencies at which the mass vibrates most strongly, i.e., in the frequency range of its natural resonance. Helmholtz resonators are also used to amplify sound, for example, in musical instruments.

[0006] Particularly in the automotive sector, where many different components are installed, the use of narrowband absorbers is helpful for absorbing the natural frequencies of components. Accordingly, there is a need for suitable acoustic components adapted to the required acoustic absorption. These acoustic components exhibit both broad, good absorption in the higher-frequency ranges, as well as particularly narrowband absorption in the low-frequency range, in order to absorb interfering frequencies such as natural frequencies. Description of the invention

[0007] The present invention provides acoustic components that overcome the above-mentioned problems. These acoustic components comprise acoustic damping based on mineral wool and / or glass wool. In addition, these acoustic components feature at least one Helmholtz resonator.

[0008] It was surprisingly discovered that the use of these typically narrowband, low-frequency tuned Helmholtz resonators significantly improved the absorption properties of acoustic components. In particular, Helmholtz resonators allow for a modification of existing acoustic damping based on mineral wool and / or glass wool to absorb frequencies that would otherwise cause disturbing noise, for example, due to natural resonance or especially in the low-frequency range.

[0009] Surprisingly, it was also shown that, in contrast to other conventional methods for acoustic damping based on mineral wool and / or glass wool, the acoustic absorption is not changed by changing the mass of the acoustic damping or the stiffness of the acoustic damping, but by using narrow-band, particularly low-frequency tuned Helmholtz resonators, the acoustic damping is improved.

[0010] The application of Helmholtz resonators in broadband acoustic damping based on mineral wool and / or glass wool allows for appropriate tuning in a desired narrowband range.

[0011] The acoustic components according to the invention are characterized by the use of broadband and narrowband absorption media.

[0012] In one embodiment, the acoustic damping used in the acoustic component consists of mineral wool and / or glass wool. In one embodiment, the acoustic damping consists of mineral wool. If necessary, these acoustic damping materials can contain additives that influence other properties, such as flammability, water absorption, etc.

[0013] By using narrowband Helmholtz resonators, it is possible to add discrete frequencies to the acoustic damping system that are to be absorbed (tuning frequencies). In this context, the term "tuning frequency" refers to the resonator being designed in such a way that its natural frequency exactly matches the frequency to be absorbed.

[0014] In addition to the acoustic damping material and the Helmholtz resonators, the acoustic component can also have a nonwoven fabric arranged on at least one side of the acoustic damping. Suitable nonwoven materials include, for example, needle-punched nonwovens made of PET or PES. This nonwoven fabric allows the corresponding acoustic damping to be protected from external influences. This nonwoven fabric can also be arranged over the Helmholtz resonators if necessary.

[0015] The at least one Helmholtz resonator present in the components according to the invention with acoustic damping is usually integrated into the acoustic damping. In one embodiment, the at least one Helmholtz resonator is integrated using inlay(s) that are inserted into recesses in the absorber. These absorber inlays containing the Helmholtz resonator can be tuned to the corresponding tuning frequency. Suitable means for achieving the desired tuning frequency are known to those skilled in the art. This includes appropriate dimensioning of the Helmholtz resonators with the length and diameter of the neck opening or the small bore, the length and diameter of the large air volume, or the diameter of the large bore.

[0016] In one embodiment, the at least one Helmholtz resonator can be integrated into the acoustic component according to the invention in such a way that it is continuously present in the acoustic damping from the top side to the bottom. In a further embodiment, the at least one Helmholtz resonator can be present in such a way that it is not completely continuously present in the acoustic damping from the top side to the bottom, but is only partially integrated in the cross-section. Remaining acoustic damping can be present both above, i.e. on the side where the sound enters, and below, i.e. on the side where the sound exits. If the Helmholtz resonator is not continuously integrated in the cross-section, the remaining acoustic damping is usually on the side of the sound input of the resonator.

[0017] By tuning the desired tuning frequencies, it is possible to tune the resonance frequencies or natural frequencies of other components against which acoustic damping is to be achieved.

[0018] According to the invention, at least two Helmholtz resonators can be present, and these Helmholtz resonators can have different tuning frequencies. This means that several identical Helmholtz inlays can be inserted to increase the absorption efficiency compared to one frequency range, and / or several differently tuned Helmholtz resonators can be used to act on multiple tuning frequencies.

[0019] The inventive use of Helmholtz resonators makes it possible to absorb resonance frequencies, especially in low frequency ranges, and thus to improve the acoustic properties of the acoustic components.

[0020] In one embodiment, the acoustic components according to the invention are those that have at least one Helmholtz resonator with a tuning frequency in a range of 500 to 1500 Hz. In one embodiment, the Helmholtz resonators are those that absorb in the frequency range above 1 kHz.

[0021] The Helmholtz resonators can be made of metal or plastic or a combination thereof. In one embodiment, these are designed as so-called Helmholtz inlays, i.e., they have a shape that can be easily inserted into existing recesses of acoustic damping based on mineral wool and / or glass wool. In one embodiment, the resonators are designed as a single or two-part unit. With a two-part resonator, the resonance chamber can be defined by a lid or cover, for example. Alternatively, this definition of the resonator can be achieved by structures to which the acoustic component according to the invention is attached. For example, the acoustic component according to the invention with the Helmholtz resonator can be attached to a corresponding vehicle structure, so that this vehicle structure accordingly covers the resonance chamber.

[0022] The acoustic damping of the acoustic component according to the invention can take various forms. Common designs of the acoustic damping include those in the form of a mat, but also as a molded, pressed, or stamped part. In one embodiment, the acoustic damping is particularly present as a molded part, obtained, for example, by pressing the material forming the acoustic damping.

[0023] The acoustic component can be designed in such a way that the Helmholtz resonators are regularly arranged throughout the acoustic component. Alternatively, or if different sections are present, the Helmholtz resonators can also be arranged in sections.

[0024] The distribution of Helmholtz resonators in the acoustic damping can be random. However, it can also be designed in such a way that these Helmholtz resonators are present precisely in the areas where high sound radiation occurs, while in other areas of the acoustic component where lower sound radiation occurs, these Helmholtz resonators are absent or other Helmholtz resonators with different tuning frequencies are present.

[0025] An advantage of the Helmholtz resonators according to the invention is that the tuning frequency of the Helmholtz resonator can be easily adjusted due to the spring / mass principle.

[0026] In a further aspect of the invention, a method for producing the acoustic components according to the invention is provided.

[0027] The method according to the invention for producing an acoustic component according to the invention comprises, in one step, providing an acoustic damping layer based on mineral wool and / or glass wool, followed by the introduction of at least one Helmholtz resonator into the acoustic damping layer. In one embodiment, the acoustic damping layer has preformed recesses for the introduction of the Helmholtz resonators, e.g., in the form of inlays, also referred to herein as Helmholtz inlays.

[0028] The acoustic component according to the invention can be manufactured in various ways. In one embodiment, the method according to the invention comprises providing the acoustic damping with the step of pressing the acoustic damping based on mineral wool and / or glass wool, in particular consisting of mineral wool and / or glass wool. In one embodiment, during this pressing of the acoustic damping, recesses are formed into which the Helmholtz resonators are inserted in a further process step. Alternatively, or in combination, the pressing can be carried out in such a way that the Helmholtz resonators are pressed with the acoustic damping based on mineral fiber and / or glass fiber.

[0029] Suitable molds, punching, and pressing processes for forming the acoustic damping, possibly with corresponding recesses, and methods for inserting the Helmholtz resonators are known to those skilled in the art and are carried out using known devices and methods. In the embodiment in which the Helmholtz resonators are inserted into the acoustic damping in preformed recesses, this can be done manually or automatically. During insertion, Helmholtz resonators can be inserted with the same tuning frequency or with different tuning frequencies.

[0030] If the acoustic component according to the invention further comprises a fleece, this is applied in an integrated or additional step to at least one side of the acoustic damping.

[0031] The fleece is bonded to the acoustic damping using known methods, e.g., force-fitting with the help of adhesives, etc.

[0032] In one embodiment, the method according to the invention is one for producing acoustic components according to the invention, wherein a mineral wool is provided and pressed into a mold with integrated recesses. The Helmholtz resonators are then inserted into the recesses preformed in the pressed part. If necessary, a fleece is then applied to at least one side of the acoustic damping. The fleece can be applied to both sides of the acoustic damping. In one embodiment, the fleece is arranged such that it is present on the side of the acoustic component according to the invention facing the sound direction.

[0033] If the acoustic component has additional layers, such as an outer thermally insulating layer or a metal layer, this is also applied subsequently.

[0034] In a further aspect, a kit is provided. This kit comprises acoustic damping based on mineral wool and / or glass fiber and at least one Helmholtz resonator. The kit is suitable for producing an acoustic component according to the invention.

[0035] In one embodiment, the kit according to the invention comprises Helmholtz resonators with different tuning frequencies and / or different materials. Providing the kit for producing an acoustic component allows the user to customize the acoustic component. For example, the user can insert Helmholtz resonators with different tuning frequencies at desired locations, thus improving the acoustic damping of the acoustic components.

[0036] In one embodiment, the kit for producing an acoustic component according to the invention further comprises nonwoven material and means for adhering the nonwoven material to the acoustic damping.

[0037] Finally, the present invention describes the use of the components or kits according to the invention for acoustic absorption, in particular for acoustic absorption in selected frequency ranges. The use of these acoustic components allows, in particular, the targeted absorption of frequencies in different ranges and thus the suppression of disturbing resonant frequencies. This applies in particular to low-frequency and narrow-band frequency ranges, which are usually not adequately absorbed by broadband acoustic damping, e.g., based on porous materials such as fibers.

[0038] The acoustic components and kits according to the invention are particularly suitable for acoustic absorption in the automotive sector. They are particularly suitable for specifically absorbing natural frequencies or resonance frequencies of other components used in the automotive sector. The acoustic components according to the invention allow for quick and easy adaptation to individual acoustic damping requirements. The use of Helmholtz resonators as easily inserted inlays in the acoustic damping enables the acoustic components to be individually adapted to the desired absorption properties.

[0039] The subject matter of the invention is further explained below with reference to the figures: The Fig. Figure 1 shows, in embodiments 1A and 1B, sections of acoustic components 1 according to the invention, here a cross-section of the acoustic component. The acoustic component has an acoustic damping 2 based on mineral wool and / or glass wool. Also shown is the at least one Helmholtz resonator 3, which is correspondingly present in the acoustic damping 2, e.g., in the form of an inlay. The sound radiation is represented by the arrow 5. The Helmholtz resonator 3 is tuned such that the sound radiation 5 is damped in a tuned manner. Furthermore, Fig. 1A, the acoustic component according to the invention is applied to a structure, e.g., vehicle structure 4. The Helmholtz resonator 3 is formed as a single piece, and the resonance chamber of the Helmholtz resonator 3 is covered by the vehicle structure 4. In the Fig. 1B, the resonator is constructed in two parts. The resonator's resonance chamber is covered by a cover 6. Fig. Figure 2 shows a further embodiment of the acoustic component 1 according to the invention. Helmholtz resonators 3a, 3b, 3c, 3d, ... are introduced into the acoustic damping 2 in sections. Section A has corresponding Helmholtz resonators 3a, 3b, ... Section B has no Helmholtz resonators, while section C has Helmholtz resonators of the same or different tuning frequencies, 3c, 3d, ... The sections can be selected accordingly so that no Helmholtz resonators are present in areas of low sound radiation, e.g. in section B of the Fig. 2. In other areas with high sound radiation, such as in sections A and C, Helmholtz resonators 3 are incorporated into the acoustic damping 2. Fig. Figure 3 shows an embodiment of an acoustic component 1 according to the invention with Helmholtz resonators 3e and 3f with different tuning frequencies. It can be seen that the Helmholtz resonators are designed differently, with the corresponding effect that when sound is emitted in the direction of arrow 5, different frequencies are absorbed in the resonators 3e and 3f, respectively. The Helmholtz resonators 3e, 3f are incorporated into the acoustic damping 2. A fleece 7 is applied to one side of this component 1, on the side of the sound inlet. The acoustic component according to the invention is mounted on a structure, such as a vehicle structure 4, in order to influence the acoustics accordingly. In Fig.Figure 4 shows measurements of the absorption coefficients of an acoustic component with mineral wool-based acoustic damping i) without a Helmholtz resonator inlay and ii) with a Helmholtz resonator inlay. The improved absorption coefficient is clearly visible in the range of approximately 950 Hz with the inlay; good absorption coefficients of the mineral wool-based acoustic damping without an inlay are only found in the range above 1500 Hz. It can be seen that the inventive acoustic component with acoustic damping and a Helmholtz resonator can dampen sound emissions in the low-frequency range in a specific manner. Reference symbol: 1 acoustic component 2 Acoustic damping 3, 3a, 3b, 3c, 3d, 3e, 3f, ... Helmholtz resonator 4 Vehicle structure 5 Sound direction 6 Cover 7 fleece

Claims

[1] Acoustic component (1), comprising an acoustic damping (2) based on mineral wool and / or glass wool, and at least one Helmholtz resonator (3). [2] Acoustic component (1) according to claim 1, characterized by that the acoustic damping (2) based on mineral wool and / or glass wool is one consisting of mineral wool and / or glass wool, in particular consisting of mineral wool. [3] Acoustic component (1) according to claim 1 or 2, characterized by that a fleece (7) is further arranged on at least one side of the acoustic damping (2). [4] Acoustic component (1) according to one of the preceding claims, characterized by that the acoustic damping (2) is in the form of a mat, as a shaped, pressed or punched part, in particular as a shaped part. [5] Acoustic component (1) according to one of the preceding claims, characterized by that the at least one Helmholtz resonator (3) consists of a metal or plastic or combinations thereof. [6] Acoustic component (1) according to one of the preceding claims, characterized by that the at least one Helmholtz resonator (3) has a tuning frequency in a range of 500 - 1500 Hz, in particular in the range of 800 - 1200 Hz. [7] Acoustic component (1) according to one of the preceding claims, wherein at least two Helmholtz resonators (3) are present and wherein Helmholtz resonators are present with different tuning frequencies. [8] Acoustic component (1) according to one of the preceding claims, characterized by that the Helmholtz resonators (3) are present regularly or in sections. [9] Acoustic component (1) according to one of the preceding claims, wherein the component has sections with Helmholtz resonators (3), optionally with different tuning frequencies, and sections without resonators. [10] Method for producing an acoustic component (1) according to one of claims 1 to 9, comprising - providing acoustic damping (2) based on mineral wool and / or glass wool; - introducing at least one Helmholtz resonator (3) into the acoustic damping (2), if necessary into preformed recesses. [11] Method for producing an acoustic component (1) according to claim 10, wherein the provision of the acoustic damping (2) comprises the step of pressing the acoustic damping (2) based on mineral wool and / or glass wool, in particular consisting of mineral wool and / or glass wool. [12] Method for producing an acoustic component (1) according to claim 10 or 11, characterized by that it comprises an additional step of applying a fleece (7) to at least one side of the acoustic damping (2). [13] Method for producing an acoustic component (1) according to one of claims 10 to 12, characterized bythat a mineral wool is provided and pressed into a mold with integrated formations; introduction of the Helmholtz resonators (3) into the preformed recesses; and optionally subsequent application of a fleece (7) to at least one side of the acoustic damping (2). [14] Kit comprising an acoustic damping (2) based on mineral wool and / or glass fiber and at least one Helmholtz resonator (3) suitable for producing an acoustic component (1) according to one of claims 1 to 9. [15] Kit according to claim 14, wherein Helmholtz resonators (3) of different tuning frequencies and / or different materials are present. [16] Kit for producing an acoustic component (1) according to claim 14 or 15, further comprising a nonwoven material (7) and means for adhering the nonwoven material to the acoustic damping (2). [17] Use of an acoustic component (1) according to one of claims 1 to 9 or of a kit according to claims 14 to 16 for acoustic absorption, in particular for acoustic absorption in selected frequency ranges, preferably for acoustic absorption in the vehicle sector.

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