Sound-absorbing structure

Abstract

To provide a sound absorption structure with variable sound absorption frequency through a simple configuration.SOLUTION: A sound absorption structure 20 includes: a container 22 placed in an environment to be absorbed (space V1); a number of powder / granular materials 24A that are contained in the container 22 and form an aggregate 24; and disturbance means (shaker 26) that increases a distance between the powder / granular materials 24A according to a wavelength range of the sound source to be absorbed. In the sound absorption structure 20, a frequency at which sound is easily absorbed is changed by changing "amplitude" of vibration that excites the aggregate 24. As a result, sound in various wavelength ranges can be absorbed with only one type of powder / granular material 24A. In addition, sound in various wavelength ranges can be absorbed without changing the thickness or height of the aggregate 24 by increasing or decreasing an amount of powder / granular material 24A in the container 22.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a sound absorption structure.

Background Art

[0002] The following Patent Document 1 describes a sound absorption device using an electrically responsive type sound wave absorption control fluid. In this sound absorption device, an ENC fluid composition is accommodated between electrodes disposed in a casing, and by applying a voltage to the electrodes, the elastic modulus and viscosity of the ENC fluid composition are increased or decreased to change the frequency of the sound wave to be absorbed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the sound absorption device of the above Patent Document 1, since a substance (EA particles) that is arrayed and bonded is used by applying a voltage, it is necessary to directly apply a voltage to the ENC fluid composition, which is a sound absorption material, inside the casing. Therefore, it may be necessary to take measures to prevent electric leakage at the installation location of this sound absorption device.

[0005] Further, in this sound absorption device, since a fluid is handled as a sound absorption material, it is necessary to strengthen the structure of the casing in order to suppress leakage of the fluid.

[0006] Thus, in this sound absorption device, in order to change the sound absorption frequency, it is necessary to construct a complicated mechanism.

[0007] In consideration of the above facts, an object of the present invention is to provide a sound absorption structure with a variable sound absorption frequency having a simple configuration.

Means for Solving the Problems

[0008] The sound absorption structure according to claim 1 includes a container disposed in a sound absorption target environment, a large number of powder particles accommodated in the container to form an aggregate, and a sound source that absorbs sound Sound emitted from disturbing means for expanding the distance between the powder particles according to the wavelength range of not the sound source the sound source.

[0009] The sound absorption structure according to claim 1 accommodates a large number of powder particles in a container as a sound absorption material. In this sound absorption structure, the distance between the powder particles is expanded by the disturbing means according to the wavelength range of the sound emitted from the sound source that is the object of sound absorption.

[0010] When the distance between the powder particles is expanded, the apparent density of the aggregate formed by the large number of powder particles accommodated in the container changes, and the elastic modulus changes. For this reason, the sound absorption characteristics change.

[0011] Thereby, with only one type of powder particle, sounds in various wavelength ranges can be absorbed. Also, without changing the thickness or height of the aggregate by increasing or decreasing the accommodation amount of the powder particles, sounds in various wavelength ranges can be absorbed.

[0012] Furthermore, since the powder particles are solids, compared with a sound absorption structure using a fluid or the like, there is no need to take measures such as water stop measures, and the sound absorption frequency can be made variable with a simple configuration.

[0013] The sound absorption structure according to claim 2 A container disposed in the sound absorption target environment, a large number of powder particles accommodated in the container to form an aggregate, and disturbance means for expanding the interval between the powder particles according to the wavelength range of the sound source to be absorbed. The disturbing means is a vibrator that vibrates a large number of powder particles accommodated in the container and at least one of the amplitude and frequency of the vibration to be vibrated is variable.

[0014] In the sound absorption structure according to claim 2, at least one of the amplitude and frequency of the vibration that vibrates the powder particles is variable.

[0015] Among these, by making the "amplitude" of the vibration to be excited variable, the energy transmitted to the granular material can be changed. For example, if the amplitude is increased, the energy transmitted to the granular material increases, and the vibration of the granular material becomes larger. As a result, the exclusive volume per particle increases, and the apparent density of the aggregate decreases.

[0016] In this way, by changing the apparent density of the aggregate, the wavelength range that can be sound-absorbed can be changed.

[0017] Also, by making the "frequency" of the vibration to be excited variable, the frequency can be brought closer to the natural frequency of the granular material to resonate the granular material. In this case, compared with the case where the granular material does not resonate, more energy is transmitted to the granular material, so the vibration of the granular material becomes larger and the apparent density of the aggregate becomes smaller. Thereby, the wavelength range that can be sound-absorbed can be changed.

[0018] The sound absorption structure according to claim 3 is the sound absorption structure according to claim 2, wherein both the amplitude and the frequency of the vibration for exciting the granular material accommodated in the container are variable.

[0019] In the sound absorption structure according to claim 3, both the amplitude and the frequency of the vibration for exciting the granular material are variable. Thereby, if the "frequency" of the vibration to be excited is brought closer to the natural frequency of the granular material to resonate the granular material, it becomes easier to change the apparent density of the aggregate. And if the "amplitude" of the vibration to be excited is changed, the apparent density of the aggregate changes.

[0020] The sound absorption structure according to claim 4 is the sound absorption structure according to claim 2 or 3, wherein the vibrator and the container are insulated by a vibration insulator.

[0021] In the sound absorption structure according to claim 4, since the vibrator and the container are insulated by a vibration insulator, the vibration of the vibrator is difficult to be transmitted to the container. Therefore, it is possible to suppress the transmission of vibration to the building where the container is installed.

Advantages of the Invention

[0022] According to the present invention, the sound absorption frequency can be made variable with a simple configuration.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0024] Hereinafter, a sound absorption structure according to an embodiment of the present invention will be described with reference to the drawings. Components denoted by the same reference numerals in each drawing mean the same components. However, unless otherwise specified in the specification, each component is not limited to one, and a plurality of them may exist.

[0025] Also, descriptions of overlapping configurations and reference numerals in each drawing may be omitted. Note that the present invention is not limited to the following embodiments, and appropriate changes such as omitting the configuration or replacing it with a different configuration can be made within the scope of the object of the present invention and implemented.

[0026] <Sound absorption target environment> In FIGS. 1(A) and 1(B), an example of the sound absorption structure 20 according to an embodiment of the present invention is shown. This sound absorption structure 20 covers at least a part of the surface of the slab 10 that partitions the two spaces V1 and V2. This sound absorption structure 20 is provided for the purpose of absorbing the sound S1 generated from the sound source O existing in the space V1 (sound absorption target environment) and reducing the sound S2 that passes through the slab 10 and propagates to the space V2.

[0027] In FIG. 1(A), for simplicity of illustration, only the direction orthogonal to the slab 10 is shown as the propagation direction of the sound S1. The sound S1 propagates in directions other than the direction orthogonal to the slab 10 according to the directivity of the sound source O. Similarly, the sound S2 also propagates in directions other than the direction orthogonal to the slab 10.

[0028] Also, the thickness of the slab 10 in FIG. 1(A) is schematically drawn. The same applies to other figures. The thickness of the slab 10 is set to the thickness required for structural strength and is appropriately set. The slab 10 includes slabs of various structures such as a concrete slab in a reinforced concrete structure, a floor material such as a structural plywood in a wooden structure, and a composite floor using a deck plate.

[0029] <Sound absorption structure> The sound absorption structure 20 according to an embodiment of the present invention includes a container 22 disposed in the space V1 which is a sound absorption target environment, a large number of powder particles 24A accommodated in the container 22, and a vibrator 26 as disturbance means.

[0030] (Container) The container 22 is formed including a housing portion 22A and a lid 22B. Among these, the housing portion 22A is formed in a rectangular frame shape with an open bottom and top, and is placed on the slab 10. The vibrator 26 is disposed inside the housing portion 22A.

[0031] The lid 22B is made of a sound-permeable material (such as a film or non-woven fabric) and closes the upper surface of the accommodating portion 22A. The lid 22B is fixed to the upper end surface of the accommodating portion 22A using an adhesive or the like. Note that a gap is formed between the lower surface of the lid 22B and the granular material 24A accommodated in the container 22. Also, the lid 22B may be omitted.

[0032] The container 22 may be formed of a material capable of holding the granular material 24A, and can be made of resin, metal, wood, or the like.

[0033] (Vibrator) The vibrator 26 is placed on the slab 10 inside the accommodating portion 22A. The vibrator 26 is formed including a vibration generating portion 26A and a diaphragm 26B.

[0034] The vibration generating portion 26A is connected to a power source (not shown) and can continuously generate vibrations. Then, due to the vibrations generated by the vibration generating portion 26A, the diaphragm 26B vibrates in the vertical direction. The vibrations generated by the vibration generating portion 26A are variable in both amplitude and frequency. Thereby, the interval between the granular materials 24A can be increased as described later according to the wavelength range of the sound generated by the sound source О which is the object of sound absorption.

[0035] Note that the "vertical direction", which is the vibration direction of the diaphragm 26B, is, in other words, the direction orthogonal to the in-plane direction of the slab 10, and is also the thickness direction of the aggregate 24 formed by the granular material 24A described later.

[0036] The diaphragm 26B is a rectangular plate-like member along the inner wall of the accommodating portion 22A, and is connected by the vibration generating portion 26A and a rod-shaped connecting portion 26C. A vibration insulator 30 is disposed in the gap between the diaphragm 26B and the accommodating portion 22A of the container 22.

[0037] The vibration insulator 30 is formed of an elastic material such as silicon or rubber, and is adhered to the end face of the diaphragm 26B and the inner wall of the housing portion 22A. By disposing the vibration insulator 30 in the gap between the diaphragm 26B and the housing portion 22A, the bottom surface of the housing portion 22A is closed. Note that the vibration insulator 30 is also disposed between the vibration generating portion 26A and the slab 10.

[0038] (Powdery and granular material) The powdery and granular material 24A is particles accommodated in the container 22. A large number of powdery and granular materials 24A are accommodated inside the container 22, and an aggregate 24 of the powdery and granular materials 24A is formed. Note that "a large number" indicates the quantity of the powdery and granular materials 24A such that the thickness H1 (thickness in the non-vibrating state) of the aggregate 24 is approximately 10 mm or more when accommodated in the container 22.

[0039] The powdery and granular material 24A is formed using silica (anhydrous silicic acid), and has a particle diameter of 200 μm or less and a bulk specific gravity of 0.2 or less. When the particles 20A vibrate, the apparent density of the aggregate 24 formed by the large number of powdery and granular materials 24A accommodated in the container 22 changes, and sound absorption performance is exhibited.

[0040] Note that, as the material used for the powdery and granular material 24A, in addition to silica, talc (magnesium hydrosilicate), hollow glass beads, calcium silicate, carbon, or the like can be used.

[0041] <Actions and effects> The sound absorption structure 20 according to the embodiment of the present invention accommodates a large number of powdery and granular materials 24A in the container 22 as a sound absorption material. In this sound absorption structure 20, the interval between the powdery and granular materials 24A is widened according to the wavelength range of the sound emitted from the sound source O that is the object to be sound-absorbed by the vibrator 26 as disturbance means.

[0042] When the interval between the powdery and granular materials 24A is widened, the apparent density of the aggregate 24 formed by the large number of powdery and granular materials 24A accommodated in the container 22 changes, and the elastic modulus changes. For this reason, the sound absorption characteristics change.

[0043] Specifically, due to the vibration generated by the vibration generating unit 26A of the vibrator 26, the diaphragm 26B vibrates in the vertical direction. As a result, as shown in FIG. 2, only the apparent density of the aggregate 24 formed by the large number of powder particles 24A accommodated in the container 22 decreases. When the apparent density of the aggregate 24 decreases, the thickness H2 of the aggregate 24 becomes larger than the thickness H1 (the thickness in the non-vibrated state) in the non-vibrated state.

[0044] Here, in FIG. 3, the sound absorption rate of the aggregate 24 in the non-vibrated state is shown by the curve K1. Similarly, the sound absorption rate of the aggregate 24 that has been vibrated and has a reduced apparent density is shown by the curve K2. As shown by these curves K1 and K2, when the aggregate 24 is vibrated, the frequency at which the sound absorption rate is excellent (in other words, the frequency at which it is easy to absorb sound) becomes smaller as indicated by the arrow L1.

[0045] At this time, when the "amplitude" of the vibration that vibrates the aggregate 24 is increased, the energy transmitted to the powder particles 24A increases, and the vibration of the powder particles 24A increases. As a result, the exclusive volume per particle increases, and the apparent density of the aggregate decreases. As a result, the frequency at which the sound absorption rate is excellent becomes even smaller.

[0046] Alternatively, when the "amplitude" of the vibration that vibrates the aggregate 24 is decreased, the energy transmitted to the powder particles 24A decreases, and the vibration of the powder particles 24A decreases. As a result, the exclusive volume per particle decreases, and the apparent density of the aggregate increases. As a result, the frequency at which the sound absorption rate is excellent becomes larger.

[0047] Thus, in the sound absorption structure 20 according to the embodiment of the present invention, by changing the "amplitude" of the vibration that vibrates the aggregate 24, the frequency at which it is easy to absorb sound can be changed. As a result, with only one type of powder particle 24A, sounds in various wavelength ranges can be absorbed. Also, without changing the thickness or height of the aggregate 24 by increasing or decreasing the accommodation amount of the powder particles 24A in the container 22, sounds in various wavelength ranges can be absorbed.

[0048] In addition, the vibrator 26 can change the "frequency" of the vibration to be generated. Thereby, the frequency of the vibration to be generated can be brought close to the natural frequency of the granular material 24A (that is, the natural frequency of the aggregate 24 formed by the granular material 24A), and the granular material 24A can be resonated.

[0049] When the granular material 24A resonates, more energy is transmitted to the granular material 24A compared to the case where the granular material 24A does not resonate, so the vibration of the granular material 24A becomes larger and the apparent density of only the aggregate 24 becomes smaller.

[0050] When the "amplitude" of the vibration to be generated is changed in a state where the granular material 24A is resonated by adjusting the "frequency" of the vibration to be generated, it is easier to change the frequency at which the sound absorption rate is excellent compared to the case where the granular material 24A is not resonating. For this reason, the effect of being able to absorb sounds in various wavelength ranges is enhanced.

[0051] Further, in the sound absorption structure 20, as shown in FIGS. 1(A) and 1(B), since the diaphragm 26B of the vibrator 26 and the container 22 are insulated by the vibration insulator 30, the vibration of the vibrator 26 is hardly transmitted to the container 22. For this reason, it is possible to suppress the transmission of vibration to the slab 10 on which the container 22 is installed.

[0052] The sound absorption structure 20 is preferably applied to a space V1 where noise of a certain frequency continuously occurs, such as a machine room in a building. Further, the sound absorption structure is preferably disposed in the underfloor space or the ceiling space in such a space V1.

[0053] According to such a configuration, even when the frequency of the noise associated with the replacement of the machine changes in the machine room, for example, it is possible to reduce the respective noises before and after the replacement of the machine without replacing the sound absorption structure 20.

[0054] Specifically, as described above, it is possible to absorb the sound S1 generated from the sound source O existing in the space V1, which is the sound absorption target environment, and reduce the sound S2, which is the noise transmitted through the slab 10 and propagated to the space V2. Further, by absorbing the sound S1 generated from the sound source O in the space V1, it is possible to suppress the sound S1 from remaining in the space V1. That is, the noise in the space V1 can also be reduced.

[0055] <Modification example> In the vibrator 26 in the present embodiment, both the "amplitude" and "frequency" of the vibration to be vibrated are variable, but the embodiment of the present invention is not limited to this. For example, the frequency of the vibration vibrated by the vibrator 26 may not be variable. Even if the frequency of the vibration to be vibrated is fixed, the sound absorption frequency can be changed by changing the amplitude, and the sound emitted from the sound source O can be absorbed.

[0056] Similarly, the amplitude of the vibration vibrated by the vibrator 26 may not be variable. Even if the amplitude of the vibration to be vibrated is fixed, the granular material 24A can be resonated by changing the frequency. Thereby, the wavelength range that can be sound-absorbed can be changed.

[0057] Further, as shown in FIGS. 1(A) and (B), in the above-described sound absorption structure 20, the lower surface of the container 22 is formed to be open, and the diaphragm 26B is arranged as the bottom plate of the container 22, but the embodiment of the present invention is not limited to this.

[0058] For example, as in the sound absorption structure 40 shown in FIG. 4(A), the container 22 may be provided with a bottom plate 22C. In this case, the bottom plate 22C is provided at an intermediate portion in the height direction of the accommodating portion 22A, and the vibration generating portion 26A of the vibrator 26 is arranged below the bottom plate 22C.

[0059] Further, a through hole is formed in the bottom plate 22C, and the connecting portion 26C of the vibrator 26 is inserted into this through hole. The diaphragm 26B of the vibrator 26 is buried and arranged inside the aggregate 24 formed by the granular material 24A. Then, a vibration insulator 30 is arranged in the gap between the hole wall of the through hole formed in the bottom plate 22C and the connecting portion 26C.

[0060] Further, for example, as in the sound absorption structure 42 shown in FIG. 4(B), the accommodating portion 22D in the container 22 may be formed in a bottomed box shape, and the connecting portion 26C of the vibrator 26 may be connected to this accommodating portion 22D. That is, in the example shown in this figure, the accommodating portion 22D also serves as the diaphragm 26B shown in FIG. 4(A) and the like.

[0061] In addition, in the present embodiment, only one vibrator 26 is provided in one aggregate 24, but the embodiments of the present invention are not limited to this. For example, as in the sound absorption structure 44 shown in FIG. 4(C), a plurality of vibrators 26 may be provided in one aggregate 24 according to the size of the aggregate 24.

[0062] In addition, in the present embodiment, the vibrator 26 is arranged below the container 22 so that the diaphragm 26B vibrates in the vertical direction, but the embodiments of the present invention are not limited to this. For example, as in the sound absorption structure 50 shown in FIG. 5(A), the diaphragm 26B may be made to vibrate in the horizontal direction.

[0063] That is, in the example shown in this figure, the container 22 is formed by the accommodating portion 22E with an open side surface and the lid 22B, and the side surface of the accommodating portion 22E is closed by the diaphragm 26B. Then, the diaphragm 26B is vibrated in the horizontal direction.

[0064] Incidentally, the "horizontal direction" is, in other words, the direction along the in-plane direction of the slab 10 and is also the direction orthogonal to the thickness direction of the aggregate 24 formed by the granular material 24A.

[0065] Furthermore, the diaphragm 26B that vibrates in the horizontal direction may be embedded inside the aggregate 24 formed by the granular material 24A as in the sound absorption structure 52 shown in FIG. 5(B). In the example shown in this figure, the container 22 is formed by the accommodating portion 22F with only the upper surface open and the lid 22B, and a through hole for inserting the connecting portion 26C is formed in the accommodating portion 22F.

[0066] Furthermore, as in the sound absorption structure 52 shown in FIG. 5(C), the accommodation part 22G in the container 22 may be formed in a bottomed box shape, and the connection part 26C of the vibrator 26 may be connected to this accommodation part 22G. It is preferable to dispose a vibration insulator 30 between the accommodation part 22G and the slab 10. That is, in the example shown in this figure, the accommodation part 22G also serves as the diaphragm 26B shown in FIG. 5(A) and the like.

[0067] Also, each of the sound absorption structures in the above embodiments is configured to absorb the sound S1 generated from the sound source O existing in the space V1 (sound absorption target environment) partitioned by the slab 10 and reduce the sound S2 that passes through the slab 10 and propagates to the space V2. However, the embodiments of the present invention are not limited to this.

[0068] For example, as in the sound absorption structures 60 and 62 shown in FIGS. 6(A) and 6(B) respectively, it may be configured to absorb the sound generated from a sound source (not shown) existing in the space V3 (sound absorption target environment) partitioned by the wall 12 and reduce the sound that passes through the wall 12 and propagates to the space V4. In this case, the container 22 can adopt an appropriate structure as long as it is fixed to the wall 12 and can accommodate the granular material 24A to form the aggregate 24.

[0069] Also, in each of the sound absorption structures in the above embodiments, the vibrator 26 is used as the disturbance means for expanding the interval between the granular materials 24A. However, the embodiments of the present invention are not limited to this. For example, as the disturbance means, a blower or the like that ejects air into the container 22 may be used.

Description of Reference Numerals

[0070] 22 Container 24 Aggregate 24A Granular Material 26 Vibrator (Disturbance Means) 30 Vibration Insulator

Claims

1. A container disposed in an environment to be sound-absorbed, A large number of powder particles accommodated in the container to form an aggregate, Disturbance means other than the sound source that expands the interval between the powder particles according to the wavelength range of the sound emitted from the sound source to be sound-absorbed, A sound-absorbing structure comprising the above.

2. A container disposed in an environment to be sound-absorbed, A large number of powder particles accommodated in the container to form an aggregate, Disturbance means that expands the interval between the powder particles according to the wavelength range of the sound source to be sound-absorbed, Comprising, The disturbance means is, A vibrator that vibrates a large number of powder particles accommodated in the container, and at least one of the amplitude and frequency of the vibration to be vibrated is variable, A sound-absorbing structure.

3. The sound-absorbing structure according to claim 2, wherein both the amplitude and frequency of the vibration of the vibrator that vibrates a large number of powder particles accommodated in the container are variable.

4. The vibrator and the container are insulated by a vibration insulator, The sound-absorbing structure according to claim 2 or 3.

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