JP7074897B2 - Soundproof structures, soundproof panels, and louvers - Google Patents

Description

The present invention relates to a soundproof structure, a soundproof panel, and a louver, and more particularly to a soundproof structure, a soundproof panel, and a louver using a plurality of flow resistors.

Soundproof structures and soundproof panels that use a flow resistor such as cloth as a sound absorbing material are already known. As an example thereof, for example, the soundproof panel described in Patent Document 1 (indicated as "soundproof sandwich panel" in Patent Document 1) can be mentioned. The soundproof panel described in Patent Document 1 is configured by sandwiching a core material made of a porous material between a pair of surface plates, forming a through hole in one of the surface plates, and mounting a metal cloth on the outer surface thereof. Has been done. Here, the metal cloth is a flow resistor, and Patent Document 1 discloses that the flow resistance of the metal cloth is 5 to 300 Pa · s / m (= Rayls).

The soundproof panel described in Patent Document 1 having the above-mentioned structure has high rigidity and exhibits high sound absorption performance in a relatively wide band. On the other hand, the soundproof panel described in Patent Document 1 is relatively heavy because it has a surface plate heavier than the porous material, and may be limited in terms of molding shape, installation space, and the like. Therefore, from the viewpoint of reducing the weight of the soundproof panel and increasing the degree of freedom in the molding shape and installation space, a simpler structure, specifically, a soundproof structure that does not use a surface plate is required.

On the other hand, for example, as in the soundproofing method disclosed in Patent Document 2, a method of arranging a fiber such as a non-woven fabric and a fabric in a room to reduce reverberant noise in the room is known. Patent Document 2 discloses, for example, reducing the noise level of a room by suspending a cloth, which is a flow resistor, from the ceiling or the like over the entire room.

Japanese Unexamined Patent Publication No. 2002-189475 Tokuhei 5-29919 Gazette

Here, as a structure simpler than the soundproof panel described in Patent Document 1, for example, a structure using only a single (one) flow resistor can be considered. In such a structure, when a general sound absorbing material (specifically, urethane, glass wool, microfiber, etc.) is used as the flow resistor, if the sound absorbing material is thinned for miniaturization and weight reduction, high sound absorption is achieved. It becomes difficult to demonstrate the performance. This is because general sound absorbing materials have high porousness (in other words, high air density) and the absorption performance changes according to the thickness, so it is difficult to absorb sound in a thin state, especially on the back surface of the sound absorbing material. If there is no (back plate), it will be difficult to achieve high sound absorption performance.

It should be noted that a general sound absorbing material has high heat insulating performance because it contains a large amount of air inside the micropores. Therefore, the use of general sound absorbing materials is limited, such as being unsuitable for use in the vicinity of equipment that generates heat.

Further, as a flow resistor other than a general sound absorbing material, a relatively thin cloth or the like can be mentioned. However, according to the present inventors, sufficient sound absorption performance cannot be obtained for a soundproof structure composed of only a single layer of cloth or the like, and specifically, the upper limit of the sound absorption rate is about 50%. It turned out (see, for example, FIG. 11).

On the other hand, as in the soundproofing method described in Patent Document 2, a plurality of cloths (specifically, fibrous bodies such as non-woven fabrics or fabrics) may be arranged side by side in a laminated manner in a room. However, in the example described in Patent Document 2, the space between the cloths is 0.45 m, and when the space between the cloths is widened to that size, it is necessary to secure a considerable space as the space for installing the cloths in the room. , Will lead to an increase in the size of the structure.

The present invention has been made in view of the above circumstances, and an object of the present invention is to solve the following object.
Specifically, the present invention solves the above-mentioned problems of the prior art, and provides a soundproof structure and a soundproof panel that exhibit high sound absorption performance while having a simpler and smaller structure. With the goal.
Another object of the present invention is to provide a louver that employs the above-mentioned soundproof structure.

As a result of diligent studies to solve the above problems, the present inventors have found that a plurality of arranged flow resistors have a specific flow resistance of 150 Pa · s / m or more and 2050 Pa · s / m or less. Is included, the thickness of the specific flow resistor is less than 11 mm, a gap is provided between adjacent specific flow resistors, and the average value of the thickness of each part of the gap is 0. We have found that the above-mentioned problems can be solved by having a thickness of 0.6 mm or more and less than 40 mm, and have completed the present invention. That is, it was found that the above problem can be solved by the following configuration.

[1] It has a plurality of flow resistors arranged side by side, and among the plurality of flow resistors, two adjacent flow resistors face each other in the thickness direction of each of the two adjacent flow resistors. The plurality of flow resistors include two or more specific flow resistors having a flow resistance of 150 Pa · s / m or more and 2050 Pa · s / m or less, and the thickness of the specific flow resistors is as follows. A soundproof structure characterized in that it is less than 11 mm, a gap is provided between adjacent specific flow resistors, and the average thickness of each portion of the gap is 0.6 mm or more and less than 40 mm. body.
[2] The soundproof structure according to [1], wherein the specific flow resistor is made of cloth.
[3] The soundproof structure according to [1] or [2], wherein the plurality of flow resistors include 3 or more and 10 or less specific flow resistors.
[4] The soundproof structure according to [3], wherein three or more and 10 or less specific flow resistors are continuously arranged in a direction in which a plurality of flow resistors are arranged.
[5] The soundproof structure according to any one of [1] to [4], wherein each of the plurality of flow resistors is a specific flow resistor.
[6] The soundproof structure according to any one of [1] to [5], which has an average value of 20 mm or less.
[7] The soundproof structure according to any one of [1] to [6], wherein the average value is 1 mm or more and 12 mm or less.
[8] The soundproof structure according to any one of [1] to [7], wherein the thickness of the specific flow resistor is less than 4 mm.
[9] The soundproof structure according to any one of [1] to [8], wherein a holding member for holding a gap is provided between adjacent specific flow resistors.
[10] The soundproof structure according to any one of [1] to [9], wherein the flow resistance of the specific flow resistor is 200 Pa · s / m or more and 1300 Pa · s / m or less.
[11] The soundproof structure according to any one of [1] to [10], wherein the soundproof structure is attached to at least one of a ceiling and a wall partitioning a space in a suspended state.
[12] A soundproof panel having the soundproof structure according to any one of [1] to [10].
[13] A louver in which the soundproof structure according to any one of [1] to [10] constitutes at least a part.

According to the present invention, it is possible to provide a soundproof structure and a soundproof panel that exhibit high sound absorption performance while having a simpler and smaller structure.
Further, according to the present invention, it is possible to provide a louver and a lattice window that employ a soundproof structure that can obtain the above effects.

It is a figure which shows an example of a preferable embodiment of the soundproof structure of this invention. It is explanatory drawing about the structure of the soundproof structure of this invention, and is the AA sectional view of FIG. It is a figure which shows the soundproof structure which concerns on the 1st modification. It is a figure which shows the soundproof structure which concerns on the 2nd modification. It is a perspective view which shows the soundproof panel of this invention. It is a figure which shows an example of a preferable embodiment of the louver of this invention (the 1). It is a figure which shows an example of a preferable embodiment of the louver of this invention (the 2). It is a figure which shows an example of a preferable embodiment of the louver of this invention (the 3). It is a figure which shows the 1st example of the soundproof structure adopted for the louver of this invention. It is a figure which shows the 2nd example of the soundproof structure adopted for the louver of this invention. It is a figure which shows the other embodiment about the louver of this invention. FIG. 8 is a plan view showing a grid of louvers illustrated in FIG. 8A. It is a figure which shows the actual measurement result and the simulation result about the vertical incident sound absorption coefficient of a single layer cloth. It is a figure which shows the simulation result of each of the Biot model, the Rigid model and the DB model. It is a figure which shows the calculation result when the absorption rate of a single layer structure is calculated. It is a figure which shows the absorption rate when the interlayer distance is changed in a three-layer structure. It is a figure which shows the absorption rate when the flow resistance of a cloth and the interlayer distance are changed in a three-layer structure. It is a figure which shows the absorption rate when the interlayer distance is changed in a five-layer structure. It is a figure which shows the absorption rate when the flow resistance of cloth and the interlayer distance are changed in a five-layer structure. It is a figure which shows the absorption rate when the interlayer distance is changed in a two-layer structure. It is a figure which shows the absorption rate when the interlayer distance is changed in a four-layer structure. It is a figure which compared the absorption rate of the present invention with the absorption rate of a simple addition system. It is a figure which shows the absorption rate when the thickness of the whole soundproof structure is fixed and the number of layers is changed. It is a figure which shows the absorption rate of each of the single-layer structure and the two-layer structure having the same total thickness. It is a figure which shows the relationship between the absorption rate at 2 kHz, and the total thickness. It is a figure which shows the relationship between the interlayer distance and the absorption rate for each of 4kHz and 12kHz. It is a figure which shows the absorption rate with respect to the normalized interlayer distance. It is a figure which shows the dependence of the total absorption value with respect to the interlayer distance. It is a figure which shows the result of having differentiated the total absorption value by the interlayer distance.

The soundproof structure, the soundproof panel, and the louver according to the embodiment of the present invention will be described in detail below with reference to the preferred embodiments shown in the accompanying drawings.
The description of the constituent elements described below is based on a typical embodiment of the present invention, but the present invention is not limited to such an embodiment. Further, in the drawings attached to the present specification, the scale of each part is appropriately changed as necessary to make it easier to see.

Further, in the present specification, the numerical range represented by using "-" means a range including the numerical values before and after "-" as the lower limit value and the upper limit value.
Further, in the present specification, "orthogonal" and "parallel" include the range of error allowed in the technical field to which the present invention belongs. For example, "orthogonal" and "parallel" mean that they are within a range of less than ± 10 ° with respect to a strict orthogonality or parallelism. Here, the error with respect to strict orthogonality or parallelism is preferably 5 ° or less, and more preferably 3 ° or less.
Further, in the present specification, "identical" and "same" include an error range generally accepted in the technical field to which the present invention belongs. Further, in the present specification, the terms "all", "all", "whole surface", etc. include not only the case of 100% but also the error range generally accepted in the technical field to which the present invention belongs, for example. It shall include the case where it is 99% or more, 95% or more, or 90% or more.

Further, "soundproofing" in the present invention is a concept including both meanings of "sound insulation" and "sound absorption". Here, "sound insulation" means "shielding sound", in other words, "not transmitting sound", and mainly reflects sound (acoustic). Further, "sound absorption" means "reducing reflected sound", and in an easy-to-understand manner, means absorbing sound (sound). In the following, "soundproofing" will be mainly "sound absorption", and "sound insulation" and "sound absorption" will be called separately to distinguish between them.

<< Outline of the soundproof structure of the present invention >>
First, the outline of the soundproof structure of the present invention will be described.
The soundproof structure of the present invention has a plurality of flow resistors arranged side by side (see, for example, FIGS. 2 to 4). In the soundproof structure of the present invention, of the plurality of flow resistors, two adjacent flow resistors face each other in the thickness direction of each of the two flow resistors. Further, the plurality of flow resistors include two or more specific flow resistors having a flow resistance of 150 Pa · s / m or more and 2050 Pa · s / m or less. Further, the thickness of the specific flow resistor is less than 11 mm. Further, a gap is provided between the adjacent specific flow resistors, and the average value of the thickness of each portion of the gap is 0.6 mm or more and less than 40 mm.

According to the soundproof structure of the present invention configured as described above, high sound absorption performance can be exhibited even though the structure is simpler and smaller. More specifically, as in the soundproof panel described in Patent Document 1, a core material made of a porous material is sandwiched between a pair of surface plates, a through hole is formed in one of the surface plates, and the material flows to the outer surface thereof. A soundproof structure configured by attaching a cloth as a resistor is known. However, in such a structure, since it has a surface plate heavier than the porous material, it becomes relatively heavy, and there is a possibility that it is limited in terms of molding shape, installation space, and the like.

On the other hand, the soundproof structure of the present invention does not use a surface plate, so that the weight is reduced and the structure is simpler. As a result, with respect to the soundproof structure of the present invention, the degree of freedom in molding shape and installation space is improved.

In particular, when there is no plate material placed on the back side of the flow resistor (in other words, the side opposite to the sound source), that is, the back plate, the soundproof structure has a small structure while ensuring breathability. , It becomes possible to absorb sound in a relatively wide frequency band. Here, "when there is no back plate" means that the back plate exists within a distance of λ / 2 from the surface of the flow resistor on the back side of the flow resistor when the wavelength of the sound to be absorbed is λ. Means not.

By the way, regarding the soundproof structure that has been made smaller and lighter as described above, for example, if a structure using a single flow resistor (that is, a single layer structure) is used, it is possible to realize an absorption rate of more than 50%. It will be difficult. This is clear from the absorption rate derived from the continuity equation of the sound wave pressure shown below.

Specifically, the absorption rate is A, the transmittance is T, the reflectance is R, the transmission coefficient is t, the reflectance coefficient is r, and T = | t | ² and R = | r | ² . Then, the following relational expression is established.
A = 1-T-R = 1- | t | ^2- | r | ²
Here, in the continuous pressure equation, which is the basic equation of the sound wave interacting with the flow _resistor of one layer, the incident sound pressure is _PI , the reflected sound pressure is PR, and the transmitted sound pressure is _PT . Sometimes (PI, _PR , and _PT are all complex numbers), _{PI = PT} + _PR .

Further, since t = P _T / P _I and _r = PR / P _I , the continuity equation of pressure is expressed as follows.
1 = t + r

From the above, the following relational expression holds between the absorption rate A and the transmission coefficient t. In the following equation, Re is the real part of the complex number and Im is the imaginary part of the complex number.
A = 1- | t | ^2- | 1-t | ²
= 1- {Re (t) ² + Im (t) ² }
-{(Re (1-t)) ² + (Im (1-t)) ² }
= 1- {Re (t) ² + Im (t) ² }
-{1-2 Re (t) + Re (t) ² + Im (t) ² }
= -2Re (t) ² + 2Re (t) -2Im (t) ²
= 2Re (t) × (1-Re (t))-2Im (t) ²
<2Re (t) × (1-Re (t))
Since the above equation is an equation of the form of 2x × (1-x) and 0 ≦ x ≦ 1, A becomes the maximum value (= 0.5) when x = 0.25. From this, it can be seen that the sound absorption rate in the single-layer structure is 0.5 at the maximum.

Regarding the above situation, the present inventors have formed a multilayer structure by arranging two or more specific flow resistors having a flow resistance of 150 Pa · s / m or more and 2050 Pa · s / m or less to form a multilayer structure, and the thickness of the specific flow resistance. It was also clarified that the absorption rate is improved by setting the gap between the adjacent specific flow resistors within a predetermined range. More specifically, when the thickness of the specific flow resistor is less than 11 mm and the average value of the thickness of each portion of the gap is 0.6 mm or more and less than 40 mm, it covers a wide frequency band. High absorption performance can be exhibited, and an absorption rate exceeding 0.5 can be obtained (see, for example, FIG. 12). In particular, when two specific flow resistors lined up with a gap in between are close to each other, the absorption rate can be further increased by the interference effect of sound in the gap.

Further, since the average value of the thickness of each portion of the gap provided between the specific flow resistors is less than 40 mm, the specific flow resistors are close to each other, and the cloth in the structure described in Patent Document 2 is used. It is much smaller than the interval (= 450 mm). As a result, unlike the structure described in Patent Document 2, it is not necessary to secure a large space for installing the cloth, and as a result, the soundproof structure can be further miniaturized.

As described above, the soundproof structure of the present invention can effectively absorb sound over a wide frequency band because there is no back plate on the back side of the flow resistor. More specifically, if the back plate is present within a distance of 1/2 times the wavelength λ of the sound to be absorbed, the flow resistor becomes a node of the sound and the sound absorbing effect becomes small at the corresponding frequency. On the other hand, if there is no back plate within the distance of λ / 2 over half the area of the surface (end face in the thickness direction) of the flow resistor, there is no frequency that becomes a sound node. Therefore, a high absorption rate can be obtained in a wide band.

By the way, in the case where the back plate is temporarily present on the back side of the flow resistor in the soundproof structure of the present invention, as a result of maximizing the local velocity of the sound in the flow resistor and increasing the sound absorption, a specific frequency (strictly speaking). , Peak frequency) improves sound absorption. Further, in the above case, the absorption rate at the peak frequency can be effectively increased by reflecting the sound on the back plate.
The back plate in the above case corresponds to a wall, a ceiling, or the like that partitions a space in which the soundproof structure of the present invention is used, and more specifically, a transportation machine such as a building wall, a floor, a ceiling, or a car. Sheet metal and flooring, general furniture boards such as desks, soundproof walls, roads, partition boards such as partitions, surfaces of home appliances, surfaces of office equipment or internal ducts, surfaces of industrial machinery, and metal plates. Applicable.

Although the configuration and effect of the soundproof structure of the present invention have been described above, the soundproof structure of the present invention can be used for various purposes, for example, a house, a hall, an elevator, a classroom, an office, and the like. Build various sound environments such as meeting rooms, schools, nursery schools and kindergartens, other buildings (specifically, factories and animal sheds, etc.), structures other than buildings, booths partitioned by partitions, and soundproof booths. Used for applications.

Further, the soundproof structure of the present invention can be used for applications other than the above, and can be used, for example, as a material for distribution such as an acoustic plate of an aircraft engine, an interior material of an automobile, a box material, and a packing material. can.
Further, the soundproof structure of the present invention can also be used as a cage that surrounds a device that becomes a noise source, for example, an air conditioner outdoor unit or a water heater. By surrounding the noise source with the soundproof structure of the present invention, it is possible to prevent noise while absorbing sound while ensuring heat dissipation and air permeability.
Further, the soundproof structure of the present invention can be used as a material for copiers, blowers, air conditioners, ventilation fans, pumps, generators, ducts and the like. Further, the soundproof structure of the present invention comprises various types of industrial equipment that emits sound such as coating machines, rotating machines, and conveyors; vehicles such as automobiles and trains, and transportation equipment such as aircraft; It can be used for general household equipment such as refrigerators, washing machines, dryers, televisions, copiers, microwave ovens, game machines, air conditioners, electric fans, projectors, personal computers, vacuum cleaners, air purifiers, and ventilation fans. ..
The soundproof structure of the present invention is appropriately arranged at a position where the sound generated from the noise source passes in the various devices described above.

<< Configuration example of the soundproof structure of the present invention >>
The configuration of the soundproof structure of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a diagram showing an example of a preferred embodiment of the soundproof structure of the present invention, and specifically, is a diagram showing a room in which the soundproof structure of the present invention is installed. FIG. 2 is an explanatory view of the configuration of the soundproof structure of the present invention, and is a sectional view taken along the line AA of FIG.

As shown in FIG. 1, the soundproof structure (hereinafter, soundproof structure 10) according to the embodiment of the present invention is used in a state of being suspended from the ceiling C that partitions the room. Specifically, for example, a string 11 is tied to one corner portion of the soundproof structure 10 (strictly speaking, a corner portion located at the same position in each of the plurality of stacked flow resistance bodies 12), and the string is tied to the string. The soundproof structure 10 is attached by hooking the 11 to a fastener (not shown) attached to the ceiling C.

The place where the soundproof structure 10 is attached is not limited to the ceiling C, and may be, for example, a side wall or a beam that partitions the room. Specifically, the above string 11 is directly attached to the side wall or the beam. The soundproof structure 10 may be attached by fixing it intentionally or indirectly.

Explaining the configuration example of the soundproof structure 10, the soundproof structure 10 has a plurality of flow resistance bodies 12 as shown in FIG. Each flow resistor 12 has air permeability, and a ventilation portion (void) is formed inside the flow resistance body 12. The flow resistor 12 is preferably made of a cloth, a thin fine through-hole plate, a thin porous sound absorbing material, or the like, and the cloth is preferably made of a cloth in terms of design and tactile sensation (texture when touched by a person). Especially preferable. Here, the cloth refers to a fiber aggregate including a non-woven fabric, a woven cloth, a knitted cloth, and the like. Further, the material of the cloth may be a natural yarn, a synthetic yarn, a metal material or the like. Further, the fine through-hole plate as the flow resistor 12 refers to a plate material having a large number of through-holes having a hole diameter of about 1 mm or less, and may be chemically formed by etching or the like, or may be physically formed through holes. It may be a worn plate. Alternatively, it may be a fine through-hole plate having a structure in which a through-hole-shaped portion is formed by a structural device. The fine through-hole plate includes a punching metal and an expanded metal.

Further, as shown in FIG. 2, the plurality of flow resistors 12 are arranged side by side at intervals. Specifically, among the plurality of flow resistors 12, two adjacent flow resistors 12 are arranged. The flow resistors 12 face each other in the thickness direction (in FIG. 2, the direction in which the flow resistors 12 are laminated). That is, each of the plurality of flow resistors 12 is laminated to form each layer in the laminated structure. In the configuration shown in FIG. 2, the number of layers in the multilayer structure (that is, the number of flow resistors 12 arranged in a laminated state) is 3, but the number is not limited to 2, and the number is 2 or more. It may be any number of.

Further, the plurality of flow resistors 12 include two or more specific flow resistors 12a having a flow resistance of 150 Pa · s / m or more and 2050 Pa · s / m or less. Further, in order to further increase the sound absorption rate, it is preferable that there are 3 or more and 10 or less specific flow resistors 12a. The flow resistance of each of these specific flow resistors 12a may be the same as each other, or the flow resistance of at least one specific flow resistor 12a is different from the flow resistance of the other specific flow resistors 12a. May be good. Further, it is preferable that the plurality of specific flow resistors 12a are continuously arranged in the direction in which the plurality of flow resistors 12 are arranged. Here, in the direction in which the plurality of flow resistance bodies 12 are lined up, the flow resistance bodies 12 are lined up at intervals with their thickness directions aligned in a certain direction. In the following, the direction in which the plurality of flow resistors 12 are lined up is also referred to as a stacking direction.

Further, for the purpose of obtaining the effect of the present invention more reliably, the plurality of flow resistors 12 may be all specified flow resistors 12a. However, the present invention is not limited to this, and the flow resistance 12 (that is, the flow resistance is less than 150 Pa · s / m, or 2050 Pa · s / m) other than the specific flow resistance 12a among the plurality of flow resistances 12 is not limited to this. A flow resistor 12) that is super may be included. In that case, a flow resistor 12 having an extremely small flow resistance may be interposed between the specific flow resistors 12a in the stacking direction.
In the following description, unless otherwise specified, the case where the plurality of flow resistance bodies 12 are all the specific flow resistance bodies 12a will be described.

Further, each specific flow resistor 12a is relatively thin, and specifically has a thickness of less than 11 mm. Here, the thickness of the specific flow resistor 12a is preferably less than 7 mm, and more preferably less than 4 mm in terms of effectively absorbing sound in the frequency band of the human voice (near 4 kHz). It is even more preferably less than 2.5 mm, and particularly preferably less than 2 mm.

Further, a gap is provided between the specific flow resistors 12a adjacent to each other. The average value of the thickness of each portion of the gap (indicated by the symbol d in FIG. 2) is 0.6 mm or more and less than 40 mm. Here, within the same gap, the thickness of each portion of the gap may vary depending on the portion. Therefore, in the present invention, attention is paid to the average value of the thickness of each portion of the gap, strictly speaking, the arithmetic mean value, and the average value is set in the above numerical range.

When the average value of the thickness of the specific flow resistor 12a and the thickness d of each portion of the gap is within the above-mentioned numerical range, the sound absorption rate can be set to more than 0.5 in a wide band. More preferably, the thickness d of each portion of the gap is preferably within the above-mentioned numerical range.

Further, when three or more specific flow resistors 12a exist and these are continuously arranged in the stacking direction, the gap between the specific flow resistors 12a is two or more (specifically, the specific flow). (A number smaller than the number of resistors 12a by 1) exists, but in this case, it is necessary that the average value of the thickness of each portion of the gap satisfies the above numerical range for each gap. Here, the average value of the thickness d of each portion of the gap is preferably 30 mm or less. Further, the average value of the thickness d of each portion of the gap may be different for each gap, or all the gaps may be the same. In other words, the three or more specific flow resistors 12a that are continuously arranged in the stacking direction may be arranged at equal intervals in the stacking direction, or may be arranged at different intervals.

Further, in order to efficiently increase the sound absorption rate, it is more preferable that the average value of the thickness of each portion of the gap is 20 mm or less in at least one of the two or more gaps, which is 1 mm. It is particularly preferable that the above is 12 mm or less.

The thickness of each portion of the gap corresponds to the distance between the layers formed by the specific flow resistor 12a, that is, the interlayer distance. Therefore, in the following, the thickness of each portion of the gap will also be referred to as the interlayer distance.

Further, from the viewpoint of keeping the thickness d (interlayer distance) of each portion of the gap constant, as shown in FIG. 2, a holding member 14 for holding the gap is provided between the adjacent specific flow resistors 12a. It is desirable to have.

Hereinafter, the flow resistance body 12 (strictly speaking, the specific flow resistance body 12a) and the holding member 14 constituting the soundproof structure 10 will be described in detail.
[Flow resistor]
In the present invention, the flow resistor 12 (strictly speaking, the specific flow resistor 12a) is a relatively thin sheet-like body, film-like body, or thin plate body, and has a thickness of less than 11 mm. Therefore, the flow resistance body 12 can be freely curved according to the arrangement location.

Further, when the thickness of the flow resistor 12 is less than 7 mm, the absorption rate in the multilayer structure in which a plurality of flow resistors 12 are laminated effectively exceeds the absorption rate in the single layer structure. Further, in order to further reduce the size and weight of the soundproof structure 10, it is more preferably less than 4 mm, further preferably less than 2.5 mm, and particularly preferably less than 2 mm. Examples of the flow resistor having a thickness of less than 2 mm include a sheet-like body made of a woven fabric, a knitted fabric, a non-woven fabric, and the like, and a film-like body.

The thickness of the flow resistor 12 may be uniform or non-uniform (may vary) within the same flow resistor 12. When the thickness of the flow resistance body 12 varies within the flow resistance body 12, the average value of the thicknesses of each portion of the flow resistance body 12 is taken as the thickness of the flow resistance body 12. Further, the thickness of each of the plurality of flow resistors 12 may be uniform or different among the flow resistors 12.

Further, the sound absorption performance of the flow resistor 12 itself largely depends on the flow resistance of the flow resistor 12. Explaining the influence of the flow resistance of the flow resistance body 12 on the sound absorption performance, when the sound passes through the ventilation portion (void) in the flow resistance body 12 and exits, the sound is absorbed by the friction generated at that time. In the following, the material portion of the flow resistance body 12 other than the ventilation portion will be referred to as a “frame” for convenience.
Here, since the flow resistor 12 having a relatively small flow resistivity that can be used as a normal sound absorbing material has a small resistance at the ventilation portion, the sound passes through the ventilation portion and the thermal viscous friction generated at that time. Contributes to sound absorption. However, since the sound flows through the ventilation portion and hardly shakes the frame, the frame itself does not contribute to sound absorption.

On the other hand, when the flow resistance of the flow resistor 12 becomes large, not only the friction when the sound passes through the ventilation portion of the flow resistor 12 but also the effect that the frame is shaken by the sound is added. More specifically, in the specific flow resistor 12a having a relatively large flow resistance, sound does not easily flow in the ventilation portion. As a result, instead of passing a part of the incident sound (sound to be absorbed) through the ventilation portion, the frame is shaken. As a result, it is considered that the vibration and mass of the frame in the specific flow resistor 12a contribute to the sound absorption effect.

As described above, in the specific flow resistor 12a having a relatively large flow resistance, the vibration and mass of the frame contribute to sound absorption. In the present invention, as described above, the flow resistance of the specific flow resistor 12a is 150 Pa · s / m or more and 2050 Pa · s / m or less.
The flow resistance of the specific flow resistor 12a is preferably 150 Pa · s / m to 1750 Pa · s / m, more preferably 200 Pa · s / m to 1300 Pa · s / m, and more preferably 250 Pa · s / m. It is more preferably s / m to 900 Pa · s / m, and particularly preferably 250 Pa · s / m to 550 Pa · s / m.

By the way, for the flow resistance of the flow resistance body 12, the air flow rate per unit area of the flow resistance body 12 with respect to the surface of the flow resistance body 12 is 0.4 cc / cm2 / using a ventilation resistance measuring device (KES F-8 manufactured by Kato Tech Co., Ltd.). It can be measured by setting it to s. This method is a method of measuring the aeration resistance by a method of constant aeration amount, and a step of sandwiching a flow resistor 12 in a measuring part and discharging air to the atmosphere through a sample with the above aeration amount, and the above-mentioned method. Similarly, it is composed of two steps of sucking the sample from the atmosphere to the device side, and it is a method of measuring the flow resistance by measuring the pressure at each step. When the flow resistance is not uniform in the surface of the surface of the flow resistance body 12, the average value of the flow resistance of each part of the surface may be adopted as the flow resistance of the flow resistance body 12. For example, three points in the flow resistance body 12 can be measured, and the average value thereof can be adopted as the flow resistance.
In addition, when multiple members with different flow resistance are used, such as attaching multiple cloths of different types to different places, or when the flow resistance is different for each region, each member or region has its own. Make the above measurements. Then, if the flow resistance obtained by combining each measurement result satisfies the above numerical range, it can be used as the specific flow resistance 12a. That is, the flow resistance body 12 may have a laminated structure in which a plurality of layers (materials) having different flow resistances are laminated, and in that case, a value obtained by combining the flow resistances of the respective layers is used. Adopted as flow resistance.
Regarding the flow resistance, the flow resistance may be measured using a system such as "Flow resistance measurement system AirReSys" manufactured by Nippon Acoustic Engineering. The method adopted by this system is the method specified in ISO 9053 (ISO 9053-1: 2018 as of 2018), and as long as this method is followed, it is possible to measure with other devices.

Next, the material of the flow resistor 12 will be described. It is desirable to use cloth as the material of the flow resistor 12 because of its high design, good texture, and ease of procurement. Examples of the cloth constituting the flow resistor 12 include woven cloth, knitted cloth, and non-woven fabric. Further, using a fiber having a fiber diameter of submicron order (order of 1 to 100 nm) as the fiber of the cloth constituting the flow resistor 12 is thinner than the conventional non-woven fabric and a high sound absorption effect can be obtained. preferable. Examples of the non-woven fabric constituting the flow resistor 12 include synthetics (trademark, manufactured by 3M, materials are polypropylene and polyester), and felts containing sound absorbing felt (materials are various fibers such as polyester, polypropylene, and PET). Non-woven fabric made of polymer fiber; non-woven fabric made of metal fiber such as Poal (manufactured by Unix, material is aluminum) and Tommy Filec SS (manufactured by Tomikawa Paper Co., material is stainless steel); non-woven fabric made of paper fiber and the like.
Examples of woven fabrics constituting the flow resistor 12 include broad (plain weave), non-combustible cloth (ISToflon Co., Ltd. IST), metal woven fabric, and metal-polymer composite fiber cloth (Seiren's conductive cloth). Etc.) etc.
It should be noted that the nonwoven fabric is generally compressed to form a thin flow resistor having a large flow resistance, and the woven fabric is relatively easy to weave densely, which is a desirable form for obtaining the effect required by the present invention. ..

The cloth fibers constituting the flow resistor 12 include aramid fiber, glass fiber, cellulose fiber, nylon fiber, vinylon fiber, polyester fiber, polyethylene fiber, polypropylene fiber, polyolefin fiber, rayon fiber, low density polyethylene resin fiber, and ethylene. Vinyl acetate resin fiber, synthetic rubber fiber, copolymerized polyamide resin fiber, fiber made of resin material such as copolymerized polyester resin fiber, fiber made of metal material such as stainless steel fiber, fiber of carbon material, fiber of carbon-containing material, and Examples include fibers of glass material.

The material constituting the flow resistance body 12 may be a material other than cloth as long as the thickness and flow resistance satisfy the above-mentioned conditions, for example, expanded metal and punching metal having a relatively thin thickness. A fine through-hole plate may be used, or a thin-layer porous sheet (membrane) may be used. Further, it is also possible to use a porous sound absorbing material other than these, for example, glass wool, rock wool, urethane foam, gypsum board or the like as the flow resistor 12.

Further, when the flow resistance body 12 made of a metal material (for example, a cloth sheet made of a metal fiber) is used, the flame retardancy of the soundproof structure 10 can be improved. The metal materials that make up the flow resistor include aluminum, titanium, nickel, permalloy, 42 alloy, koval, nichrome, copper, beryllium, phosphorus bronze, brass, white, tin, zinc, iron, tantalum, niobium, molybdenum, and so on. Examples thereof include various metals such as zirconium, gold, silver, platinum, palladium, steel, tungsten, lead, stainless steel, and iridium, and alloy materials in which the above-mentioned various metals are combined. Among these, copper, nickel, stainless steel, titanium and aluminum are preferable from the viewpoint of cost and availability.

Further, the flow resistor 12 made of a metal material can improve ozone resistance and can shield radio waves. Furthermore, since the flow resistor 12 made of a metal material has conductivity and is difficult to be charged, minute dust and dirt are not attracted to the flow resistor 12 side by static electricity, and are inside the flow resistor 12. It is possible to prevent the sound absorption performance from being deteriorated due to clogging with dust and dirt. Further, since the metal material has a high reflectance to radiant heat due to far infrared rays, the flow resistor 12 made of the metal material also functions as a heat insulating material for preventing heat transfer due to radiant heat. At that time, since there are many voids having a relatively small size in the flow resistance body 12, the flow resistance body 12 functions as a reflective film against radiant heat.

Further, the surface of the flow resistor 12 made of a metal material may be metal-plated from the viewpoint of suppressing rust. At this time, the size of the void may be adjusted to be smaller by applying metal plating to at least the inner wall surface of the void in the flow resistor 12. Further, when applying metal plating, it is desirable to apply metal plating so as not to form nodal points between fibers.

Further, the flow resistor 12 made of cloth or the like has functions other than sound absorption performance, such as flame retardancy, design, waterproofness, water repellency, oil repellency, stain resistance, wear resistance, weather resistance and shape retention. For the purpose of imparting properties and the like, processing for modifying the properties of the flow resistor 12 may be performed. Since the soundproof structure 10 using the flow resistor 12 subjected to the above processing can be installed in a place where the soundproof structure has not been used in the past, and can be used in that place. , Market value and usefulness increase.

On the other hand, depending on the processing method, the air permeability and sound absorption of the flow resistor 12 may be lowered. In order to maintain the sound absorption property of the flow resistor 12, it is necessary to select an appropriate processing method with respect to the characteristics (characteristics to be modified) imparted to the flow resistor 12. That is, as the cloth constituting the flow resistor 12, there is a demand for a cloth that has been processed to impart desired characteristics while maintaining sound absorption. As the cloth constituting the flow resistor 12, there has been a cloth on which a predetermined image is printed in order to improve the design, but the type (fabric) of the cloth is limited, and further printing is performed. Since it is necessary to submit an image at the time of request, processing cost and labor are required.

For the above reasons, when the cloth constituting the flow resistor 12 in the present invention is processed, among the mechanical properties on the surface of the cloth, the physical properties related to sound absorption (specifically, the flow resistance and the fiber strength rate). Etc.) is preferably maintained. In other words, among the flow resistance bodies 12 of the present invention, the flow resistance of the processed portion after processing is preferably 150 Pa · s / m or more and 2050 Pa · s / m or less. If the flow resistance after processing of the processed portion is within this range, a high sound absorption effect can be obtained even when the flow resistance body 12 after processing is used.

To give a specific example, as a method of imparting design to the cloth forming the flow resistor 12 (for easy understanding, an image or a pattern is attached to the processed portion), dyeing with a dye or coloring with a paint is performed. , And transfer of printed film. Of these, dye dyeing is considered preferable from the viewpoint of maintaining the flow resistance of the processed portion after processing.

To explain with another example, as the water-repellent treatment for imparting water repellency to the cloth forming the flow resistor 12, a method of laminating a water-repellent coating layer on the cloth surface and a method of immersing the cloth in a chemical solution are used. Then, a method of chemically binding a water-repellent component to the fibers of the cloth cloth can be mentioned. Of these, from the viewpoint of maintaining the flow resistance of the processed portion after processing, the latter method, that is, a method of chemically binding a water-repellent component to the fibers of the cloth fabric is considered to be preferable.

The holding member interposed between the flow resistance body 12 and the flow resistance body 12 by applying the water repellent treatment to the flow resistance body 12 while maintaining the flow resistance of the processed portion after processing within the above numerical range. 14 can also be protected from water or the like when it is splashed with water or other liquid (hereinafter, water or the like). As a result, the range of choices for the material of the holding member 14 can be expanded to a material having low durability against water, and for example, paper or the like can be used. As described above, by applying the water-repellent treatment to the flow resistance body 12 as described above, the entire soundproof structure 10 can be protected.

By the way, examples of the processing applied to the cloth forming the flow resistor 12 include the above-mentioned dyeing processing and water-repellent processing, for example, printing processing, sublimation transfer processing, brushing processing, antibacterial processing, water absorption processing, and speed. Dry processing, morphological stability processing, wrinkle-proof processing, photocatalyst processing, ultraviolet-cutting processing, dust-proof processing, cool feeling processing, negative ion processing, flame-proof processing, pollen adhesion prevention processing, and pest repellent processing are included, and at least of these. One may be applied to the processed part.

The ratio of the region belonging to the processed portion to the surface of the flow resistor 12 (strictly speaking, the end face in the thickness direction) is preferably more than 5%, more preferably more than 30%, more preferably more than 70%. Is particularly preferable. That is, the flow resistance body 12 may include a processed portion and a non-processed portion, and the flow resistance (breathability) may be the same between the processed portion and the non-processed portion.

Next, the number of layers in the soundproof structure 10, that is, the number of flow resistance bodies 12 (strictly speaking, the specific flow resistance body 12a) will be described. It is necessary that there are two or more. Further, from the viewpoint of increasing the absorption rate (strictly speaking, the maximum absorption rate when the flow resistance is changed), the number of layers is preferably 3 or more. When the number of layers is three or more, it is possible to suppress the reduction of sound absorption due to interference and effectively absorb sound in a wide band.
On the other hand, as the number of layers increases, the production of the soundproof structure 10 becomes complicated and the cost increases. Therefore, the number of flow resistors 12 is preferably 10 or less.

The size and shape of each of the plurality of flow resistors 12 (strictly speaking, the plurality of specific flow resistors 12a) may be the same among the flow resistors 12, or for each flow resistor 12. It may be different. Here, the planar shape of each flow resistor 12 is not particularly limited, and is, for example, a polygon including a rhombus, a square, a rectangle, a parallel quadrilateral, a trapezoidal or other quadrangle, a triangle, a pentagon, a hexagon, and the like. , Circular, oval, or irregular.
Further, each of the plurality of flow resistors 12 arranged along the stacking direction is completely overlapped when visually recognized from the stacking direction (that is, the flow resistors 12 are not displaced). Alternatively, some of the flow resistors 12 may be arranged in a misaligned state.

Next, the thickness of each part of the gap between the flow resistance bodies 12 (strictly speaking, the specific flow resistance body 12a) will be described. In order to make the absorption rate more than 0.5, the average thickness of each part of the gap is averaged. It is necessary that the value is 0.6 mm or more. Further, as the average value of the thickness is increased, the sound absorption characteristic of the soundproof structure 10 tends to increase (see, for example, FIG. 24), so that the average value of the thickness should be 1.5 mm or more. It is preferably 2.0 mm or more, more preferably 3.0 mm or more, and particularly preferably 3.5 mm or more.

On the other hand, when the thickness of each portion of the gap is 40 mm or more, almost no increase in absorption characteristics can be obtained (see, for example, FIGS. 24 and 25). Therefore, it is desirable that the average value of the thickness of each portion of the gap is less than 40 mm. The average thickness is preferably 30 mm or less from the viewpoint of further downsizing the soundproof structure 10. Further, when three or more flow resistance bodies 12 are present and two or more gaps are present, the average value of the thickness of each portion of the gaps in at least one gap is from the viewpoint of effectively enhancing the absorption characteristics. Is more preferably 20 mm or less, and particularly preferably 1 mm or more and 12 mm or less.

Here, to explain the method of measuring the thickness of each portion of the gap, two flow resistors 12 (strictly speaking, the specific flow resistor 12a) sandwiching the gap are stretched, and the flow resistor 12 is preferably straightened. When tension is applied to the extent that the two flow resistors 12 are parallel to each other, the thickness of each part of the gap is uniform, so that the thickness of one part of the gap is set as a caliper. It may be measured using a measuring instrument such as a thickness gauge. Further, a metal plate having a fixed thickness such as a gap gauge (feeler gauge) may be inserted into the gap, and the maximum value of the gauge that can be inserted without being caught may be specified as the gap thickness. In this case, the measured thickness corresponds to the average value of the thickness of each portion of the gap.
Further, even when the two flow resistance bodies 12 are not parallel to each other under the above conditions, the minimum value and the maximum value of the gap can be measured along the inclination direction of each flow resistance body 12. The average value of the minimum value and the maximum value at this time may be adopted as the average value of the thickness of each portion of the gap.

On the other hand, when the two flow resistance bodies 12 sandwiching the gap are greatly bent, the thickness of each portion of the gap becomes non-uniform (varies). In such a case, the thickness of several gaps is measured by a measuring instrument. Then, the average value of the thickness is calculated by averaging the thicknesses of the measured points. Specifically, the curvature of the deflection of each flow resistor 12 is specified. Here, at the inflection point of deflection (corresponding to the extreme value of curvature), the distance between the flow resistors 12 becomes maximum or minimum. This is because, for example, in the configuration in which the flow resistance body 12 is suspended as shown in FIG. 4, the position of the center of gravity of the flow resistance body 12 hangs down most, and this becomes an inflection point. Then, the thickness is measured for the gap at the position of the inflection point. Then, the thickness is measured for the gap at the end of the flow resistor 12 (for example, a fixed portion in the flow resistor 12). Here, if there is a variation in the thickness within the gap at the end of the flow resistor, the average value of the maximum value and the minimum value is adopted as the thickness. The average value of the two thicknesses (that is, the thickness at the inflection point and the thickness at the end of the flow resistor 12) measured by the above procedure can be adopted as the average value of the thickness of each portion of the gap. ..
Further, when the holding member 14 is arranged between the two flow resistance bodies 12 sandwiching the gap, the height of the holding member 14 can be regarded as the thickness (interlayer distance) of each portion of the gap.

In the following explanation, unless otherwise specified, the thickness of each part of the gap is uniform, and the explanation is based on the assumption that the thickness of each part of the gap is equal to the average value of the thickness of each part. do.

Incidentally, when there are two or more gaps, the thicknesses may be the same between the gaps, or the thickness may be different between one gap and the other gaps. Further, when there are a plurality of gaps having different thicknesses, it is preferable to arrange the flow resistor 12 so that the thickness of each portion of the gaps becomes larger on the side closer to the sound source. Further, when there are three or more gaps, it is preferable to arrange the flow resistor 12 so that the thicknesses are the same between the gaps at symmetrical positions in the stacking direction. For example, when five flow resistance bodies 12 are arranged, there are four gaps, of which two gaps have a thickness of 2 mm and the remaining two gaps have a thickness of 1 mm. Then, it is preferable to arrange them in the order of 1 mm-2 mm-2 mm-1 mm, and more preferably to arrange them in the order of 2 mm-1 mm-1 mm-2 mm.

[Holding member]
As shown in FIG. 2, the holding member 14 is a hollow frame body arranged between the flow resistance bodies 12 in the stacking direction. The planar shape and size of the holding member 14 are determined according to the planar shape and size of the flow resistance body 12, and are specifically the same. The flow resistor 12 is attached to both sides of the holding member 14 (both end faces in the height direction of the holding member 14). The height of the holding member 14 is the same as the thickness of each portion of the gap between the flow resistance bodies 12 (strictly speaking, the specific flow resistance body 12a), that is, the interlayer distance, and is 0.6 mm or more and less than 40 mm. ..

The hollow frame body constituting the holding member 14 is not particularly limited, but from the viewpoint of ensuring sufficient strength and rigidity to support the flow resistance body 12 and reducing the weight, for example, A honeycomb core having a plurality of openings (cells) is preferable. However, in addition to this, a plate-shaped member having a plurality of openings such as a punching metal and an expanded metal may be used as the holding member 14.

Examples of the material of the holding member 14 include flammable materials such as paper material, wood, and resin material. Examples of the paper material include Japanese paper, paper, a corrugated cardboard structure using a pulp raw material, a honeycomb corrugated cardboard structure, a board, and the like. Examples of the resin material include PET (polyethylene terephthalate), TAC (triacetyl cellulose), PVDC (polyvinylidene chloride), PE (polyethylene), PVC (polyvinyl chloride), PMP (polymethylpentene), and COP (cycloolefin). Polymer), Zeonoa, Polycarbonate, PEN (Polyethylene Naphthalate), PP (Polypropylene), PS (Polypropylene), PAR (Polyallylate), Aramid, PPS (Polyphenylene Sulfide), PES (Polyethersulfon), Nylon, PEs ( Polyester), COC (Cyclic Olefin Copolymer), Diacetyl Cellulose, Nitro Cellulose, Cellulose Derivatives, Polyamide, Polyamideimide, POM (Polyoxymethylene), PEI (Polyetherimide), PMMA (Polymethylmethacrylate), Polyrotaxane (Slide) (Ring material, etc.), and polyethylene, etc. can be mentioned. Further, a so-called corrugated plastic structure mainly using polypropylene or polycarbonate can also be used.
Further, as a material of the holding member 14, a flame-retardant material can also be mentioned. Examples of the flame-retardant material include metal materials, inorganic materials, flame-retardant plywood, flame-retardant fiber plates, and flame-retardant plastic plates. Examples of the metal material include aluminum, steel, titanium, magnesium, tungsten, iron, steel, chromium, chromium molybdenum, dichromium molybdenum, and alloys thereof. Examples of the inorganic material include glass, concrete, gypsum board, sapphire, and ceramics. Further, by coating a flammable material with an aramid resin or the like, it can be used as a flame-retardant material.
Examples of the material of the holding member 14 include materials containing carbon fibers such as carbon fiber reinforced plastics (CFRP), carbon fibers, and glass fiber reinforced plastics (GFRP).
Further, the holding member 14 may be formed by combining a plurality of types of the above-mentioned materials.

In the soundproof structure 10 shown in FIGS. 1 and 2, the flow resistance body 12 is supported by being fixed to the holding member 14, but the flow resistance body 12 is held without using the holding member 14. You may. The method of holding the flow resistance body 12 without using the holding member 14 is not particularly limited, but for example, as shown in FIG. 3, a plurality of flow resistance bodies 12 (strictly speaking,) constituting the soundproof structure 10x. Each of the specific flow resistors 12a) may be suspended from the ceiling C in a hanging curtain shape. Further, as shown in FIG. 4, at a position directly below the ceiling C, each of the plurality of flow resistance bodies 12 (strictly speaking, the specific flow resistance body 12a) constituting the soundproof structure 10y has a constant pitch in the vertical direction. It may be arranged in layers with. Explaining the configuration shown in FIG. 4, it is preferable that a plurality of rod-shaped columns 16 are arranged on the ceiling at appropriate intervals, and a plurality of flow resistors 12 can be attached to each of the columns 16 at regular intervals in the vertical direction. In such a configuration, when cloth is used as the flow resistor 12, each cloth may be arranged in a stretched state between the columns 16, or may be arranged in a loose state as shown in FIG. You may.
From the viewpoint of exhibiting high sound absorption performance in a wide band, the soundproof structures 10, 10x and 10y shown in FIGS. 1 to 4 have end faces (specifically, a flow resistor 12 forming the outermost layer). It is desirable that the surface) is arranged so as to be away from the ceiling C or the like, and an air layer exists between the surface and the rigid body.

<< About the soundproof panel of the present invention >>
Next, the soundproof panel of the present invention configured by using the above-mentioned soundproof structure 10 will be described with reference to the configuration of the illustrated soundproof panel B in FIG. 5 as an example.

As shown in FIG. 5, the soundproof panel B has a panel body Bx configured by the soundproof structure 10 and a frame body By surrounding the panel body Bx, and is a panel material having sound absorbing performance (that is, a sound absorbing panel). ). The soundproof panel B shown in FIG. 5 is partially composed of the soundproof structure 10, but the present invention is not limited to this, and the entire soundproof panel B is composed of the soundproof structure 10. May be good. Further, of the panel body Bx and the frame body By, only the frame body By may be configured in the soundproof structure 10.

The soundproof panel B is used for forming a soundproof member, a soundproof box, a soundproof enclosure structure, a soundproof chamber, and the like. Soundproofing members include, for example, those used as building materials, those used for air conditioning equipment, those installed in openings such as room windows, those installed on ceilings, those installed for floors, and indoors. Those installed in the opening of the room such as doors or windows, those installed inside the toilet, those installed on the balcony, those used for room tone adjustment, those for constructing a simple soundproof room, pet shed Those that are installed in amusement facilities, those that are used for sound insulation at construction sites, those that are installed in the rooms of moving objects such as vehicles (for example, passenger rooms in automobiles, trains, airplanes, etc.), In addition, those installed in tunnels can be mentioned.

The soundproof box is a box body constructed by arranging a plurality of panel materials including the soundproof panel B in a box shape, and is used, for example, for construction of buildings and other structures, transportation, and distribution. be able to. The soundproof box using the soundproof panel B can prevent the sound from leaking from the inside of the box to the outside or the sound from the outside into the inside of the box. The soundproof box is used, for example, as a pet shed, a housing of a device that becomes a noise source, or the like.

The soundproof enclosure structure is configured by arranging a plurality of panel materials including the soundproof panel B as an outer peripheral wall (that is, a partition), and by arranging a sound source in the space inside the outer wall (that is, a partition), a sound absorbing effect on noise is exhibited. do. The soundproof enclosure structure is not limited to the one in which the soundproof panels B are arranged in a ring shape so as to surround the sound source, and may be a partition composed of one or two panels. When a partition as a soundproof enclosure structure is used, sound can be suitably shielded between the partitioned spaces. Further, the movable partition made of the soundproof panel B of the present invention is thin and light, so that it is easy to carry, and there is a great merit in using this.
Further, the soundproof enclosure structure may be used by being attached to a chair, a desk or the like.

A soundproof room is a room composed of a plurality of panel materials including a soundproof panel B used for the walls or ceiling of the room, and has a sound absorbing effect against the voices of people who are active indoors or the noise generated outdoors. Demonstrate.
The sound source described above may be a device that emits sound or a human voice.

<< About the louver of the present invention >>
The soundproof structure of the present invention can be used as a louver 110 as shown in FIGS. 6A to 6C. That is, according to the present invention, it is possible to realize a louver whose at least a part is configured by the above-mentioned soundproof structure. This louver (specifically, the louver 110 illustrated in FIGS. 6A to 6C) is a facility for private room space such as a personal booth, a centralized booth, a work booth, and a conference room space booth (hereinafter, booth). It can be used for V). Specifically, regarding booth V, it is often necessary to open the upper part (ceiling part) according to the air permeability, the relationship with fire extinguishing equipment, and the regulations such as the Fire Service Act. In that case, as shown in FIG. 6C, outside sounds (including reflected sounds on the ceiling C of the room where the booth V is installed) enter the booth V through the open portion and make noise for the people inside the booth V. Can be. On the contrary, as shown in FIG. 6B, the voices and sounds emitted by the person in the booth V are diffused to the outside of the booth V through the open portion, and as a result, confidential information is leaked or becomes noise. Problems arise.

Therefore, as shown in FIGS. 6A to 6C, by attaching the louver 110 configured by the soundproof structure of the present invention to the open portion of the booth V, the air permeability and other conditions (relationship with firefighting equipment, etc.) can be improved. Sound can be absorbed while maintaining. Further, the soundproof structure of the present invention constituting the louver 110 is mainly composed of the flow resistance body 12, and the flow resistance body 12 is generally a lightweight structure. Therefore, even if the louver 110 installed in the open portion (that is, the ceiling portion) of the booth V should fall, safety can be ensured.

Here, the louver 110 may be configured only by a flow resistor such as a cloth forming a soundproof structure, or may be configured by combining a flow resistor forming the soundproof structure and a frame supporting the flow resistor. good. Here, as the frame, it is preferable to use a frame made of a hard material such as plastic, metal, or wood.

Further, in the soundproof structure constituting the louver 110 (louver 110x in FIG. 7B), the flow resistance bodies 12 (strictly speaking, the specific flow resistance bodies 12a) are arranged side by side in a grid pattern as shown in FIG. 7A. Alternatively, they may be arranged along one direction so as to be parallel to each other as shown in FIG. 7B.

Further, as shown in FIG. 8A, the louver 210 configured by the soundproof structure of the present invention can be used for the air supply fan R arranged in the duct D for exhaust heat or ventilation. As a result, the sound can be blocked by the louver 210 while keeping the air flowing through the duct D. Here, the flow resistance body 12 (strictly speaking, the specific flow resistance body 12a) of the soundproof structure constituting the louver 210 functions as a grid of the louver 210. The grid of the louver 210 may be composed of only the flow resistance body 12, or a hard plate material 211 may be attached to the side end portion of the flow resistance body 12. Specifically, as shown in FIG. 8B, a grid of the louver 210 can be formed by attaching a plastic or metal frame material (plate material 211) to the outer edge portion of a substantially rectangular cloth. With such a structure, it is possible to prevent fingers and the like from getting inside the air supply fan R. Further, it is possible to impart sound absorption to the louver 210 while maintaining the original function of the louver 210 to prevent foreign matter or the like derived from the air supply fan R from scattering to the outside of the duct D.

Further, the soundproof structure of the present invention may be used for applications other than the louvers 110 and 210, and can be used, for example, for lattice windows, blindfolds, awnings, and the like. That is, according to the present invention, it is also possible to realize a lattice window whose at least a part is formed by the above-mentioned soundproof structure.

The present invention will be described in more detail with reference to the examples described below. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention should not be construed as limiting by the examples shown below.

The absorption rate of the soundproof structure of the present invention was examined by simulation using the finite element method software COMSOL ver5.3 (COMSOL Inc.). Here, the "absorption rate" is "1-transmittance-reflectance" in a system in which a wall is not provided on the back surface side of the flow resistor and both sound transmission and reflection can exist. It is a value defined by.

In this simulation, a flow resistor was used as a cloth, and the cloth was modeled during the simulation. Regarding the modeling of the cloth, as a result of diligent studies by the present inventors, not only the frictional heat absorption model of the ventilation part of the cloth but also the vibration of the frame (material part) of the cloth is incorporated into the simulation model, and the experimental result is obtained. It was revealed that it was reproduced very well.

By the way, for the calculation of the sound absorbing material which is the flow resistance, the Delaney-Bazzley-Miki model which is a general empirical formula or the Equivalent Fluid model which calculates only the passage of the sound of the ventilation part without vibrating the frame ( Ridd model) is used. According to these models, it is known that the absorption rates of felt and glass wool, which are ordinary porous sound absorbing materials, can be accurately reproduced.

However, the present inventors have clarified that it is difficult to satisfactorily reproduce the experimental results of a flow resistor having a large flow resistance with the above model. Specifically, it was found that the absorption rate and the sound absorption band at the sound absorption peak frequency cannot satisfactorily reproduce the measured values in the calculation results when calculated using the Ridid model.

Therefore, the present inventors have adopted the Biot model in order to calculate even the vibration of the frame in the flow resistor. Specifically, the present inventors have clarified that the measured value can be reproduced satisfactorily by applying it to the Biot model and calculating including the vibration of the frame in the flow resistor.
More specifically, we compared experiments and simulations on the absorptivity of single-layer fabrics. Toray GS2000, which has a relatively high flow resistance, was used as the target cloth. The flow resistance of this cloth was 694 Pa · s / m when measured using KES F-8 manufactured by Kato Tech Co., Ltd. Further, the surface density was obtained by cutting the above cloth into 10 cm × 10 cm, measuring the weight of the cut cloth by weighing, and dividing by the area. The surface density obtained in this way was 200 g / m ² . The thickness of the cloth was measured with a Mitutoyo Digimatic Thickness Gauge. The measurement result of the thickness was 530 μm.
Then, the above cloth was measured using an acoustic tube. Specifically, the cloth was arranged so as to face the sound source side, and a wall (specifically, an aluminum plate having a thickness of 20 mm) was placed 40 mm apart on the back side thereof to form a cloth sound absorbing structure with a back wall. In addition, the acoustic tube measurement method was evaluated by preparing a measurement system for the vertical incident sound absorption coefficient using two microphones in accordance with "JIS A 1405-2". Here, the internal diameter of the acoustic tube was set to 4 cm, and a system capable of measuring up to about 4000 Hz was used.
The same measurement as the above-mentioned interacoustic measurement method can be performed using WinZac MTX manufactured by Nippon Acoustic Engineering.
The measured vertical incident sound absorption coefficient is shown in FIG. As can be seen from FIG. 9, the characteristic of the measurement result is that the reflection spectrum is asymmetric with respect to the frequency, and the vertical incident sound absorption coefficient is biased toward the low frequency side.
On the other hand, a simulation was performed for the above structure. Specifically, an acoustic tube was modeled using a COMSOL acoustic module, a cloth portion was set as a porosity member, and the above parameters were input to the above-mentioned Biot model to carry out a simulation.
The vertical incident sound absorption coefficient obtained as a simulation result is shown in FIG. As can be seen from FIG. 9, the experimental results and the simulation results are in good agreement, including the tendency that the vertical incident sound absorption coefficient increases asymmetrically on the low frequency side.
Furthermore, the above simulation results (calculation results in the Biot model) were compared with other porosity models. As a comparative model, a DB model (Delany-Bazley-Miki model), which is an empirical formula for flow resistors, was used, and the above-mentioned flow resistance and thickness were input to the COMSOL model for calculation. As another comparative model, the Rigid model in which the material part (frame) of the cloth is fixed in the JCA model, which is a semi-empirical type of sound absorption of the flow resistor, that is, the model that eliminates the vibration of the lattice of the porous body is used. , Made a calculation.
Regarding the above two comparative models, it is known that simulation results that are in good agreement with the experiment can be obtained when targeting flow resistors with relatively small flow resistance. The simulation results when each of these models and the above-mentioned Biot model are used are shown in FIG. As can be seen from FIG. 10, it was found that the DB model and the Rigid model showed similar tendencies to each other, and as a characteristic tendency, the graph shape of the sound absorption coefficient became substantially symmetric with respect to the frequency.
On the other hand, when the Biot model is used, the graph shape of the vertically incident sound absorption coefficient becomes an asymmetrical shape that is biased toward the low frequency side, and as described above, the experimental results are well reproduced.
From the above, the present inventors have confirmed that in a system having a relatively high flow resistance as in the present invention, the actual phenomenon can be reproduced well by using the Biot model. Here, the system having a relatively high flow resistance is, to be precise, a case where the flow resistivity is extremely large because the flow resistance is large and the thickness is small. Incidentally, it is considered that the flow resistivity of the above-mentioned cloth (GS2000) is 130000 Pa · s / m ² , and the flow resistivity of urethane foam and glass wool usually used as a sound absorber is about 10000 Pa · s / m ² . It is a remarkably high value. As a result, a large resistance is generated when passing through the ventilation portion of the cloth, which is considered to be the cause of the sound vibrating the material portion (frame) of the cloth.
Since the Biot model has a wider range of application than the DB model and the like, even if it is applied to a flow resistor having a low flow resistance, the calculation is in good agreement with the experiment. Therefore, there is no problem in examining the sound absorption of various types of flow resistors using the Biot model.

The simulation by the Biot model was carried out under the conditions of Examples 1 to 7 shown below. In addition, when carrying out the simulation under the conditions of each example, the simulation was carried out under the conditions of the comparative examples shown below.

(Comparative example)
As a model of the flow resistor, a cloth with a density of 0.6 g / m ³ and a thickness of 240 μm is assumed, and the flow resistance of the cloth is changed to 100, 200, 400, 600, 800 and 1000 Pa · s / m for simulation. Carried out. Moreover, in the comparative example, the absorption rate of a single cloth (single layer structure) was calculated. The calculation result of the comparative example is shown in FIG.

As can be seen from FIG. 11, as the flow resistance increases, the absorption rate increases even with a single thin cloth (single layer structure). However, as shown in FIG. 11, in the single layer structure, the absorption rate does not exceed 50%. This is a problem that can occur when a single-layer structure is adopted in order to reduce the size and weight of the soundproof structure, as described in the section "Problems to be Solved by the Invention".

(Example 1)
The layers of the cloth having the same density and thickness as in the comparative example were made into three layers instead of a single layer, and the absorption rate was calculated by changing the thickness (interlayer distance) of each part of the gap provided between the cloths. In Example 1, first, the flow resistance of the cloth constituting each layer was set to 400 Pa · s / m, and the interlayer distances were changed to 2, 4, 6, 8 and 10 mm. FIG. 12 shows the calculation result of the absorption rate when the interlayer distance is changed.

As can be seen from FIG. 12, the absorption rate of the three-layer structure is the absorption rate of the single-layer structure over a wide band from low frequency to high frequency regardless of the above-mentioned values of the interlayer distance (calculation of comparative example). Result) is exceeded. Specifically, for example, since the wavelength of the sound of 10000 Hz is about 343 mm, the thickness (4 to 20 mm) of the multilayer structure of Example 1 is a system much thinner than the above wavelength. It has been clarified that even in such a thin system, the absorption rate can be increased by using multiple layers of cloth. The thickness of the multi-layer structure is the thickness of the entire multi-layer structure (in Example 1, the total value of the thickness of each of the three layers and the distance between the two layers), and is also referred to as "total thickness" below.

Next, the absorption rate at a frequency of 12 kHz was calculated by changing both the flow resistance of the cloth and the interlayer distance. FIG. 13 shows the calculation result of the absorption rate when the flow resistance of the cloth and the interlayer distance are changed. As can be seen from FIG. 13, when the cloth of each layer has an appropriate flow resistance and the interlayer distance is a certain distance or more, a particularly high absorption rate can be obtained. More specifically, the highest absorption rate can be obtained when the flow resistance is about 400 Pa · s / m.

Here, since the absorption rate in the single-layer structure (that is, the system of the comparative example) was 50% at the maximum, the absorption rate of a value (55%) or more that is 10% larger than that value is higher than that in the single-layer structure. It is considered to be essentially a large absorption rate. In order to realize this absorption rate, it is necessary that the flow resistance of each cloth is 150 to 2050 Pa · s / m and the interlayer distance is 0.6 mm or more in the structure in which the cloths are multi-layered. Become.
Table 1 shows the conditions for obtaining an absorption rate of 55% or more.

(Example 2)
In Example 2, the number of layers was changed from Example 1 to five, and the absorption rate was calculated under the same conditions as in Example 1. FIG. 14 shows the calculation result of the absorption rate when the interlayer distance is changed. Further, FIG. 15 shows the calculation result of the absorption rate when the flow resistance of the cloth and the interlayer distance are changed. As can be seen from FIGS. 14 and 15, a higher absorption rate can be obtained by increasing the number of layers.
Table 2 shows the conditions for obtaining an absorption rate of 90% or more.

(Examples 3 and 4)
In Example 3, the number of layers was changed from Example 1 to two layers, and the absorption rate was calculated under the same conditions as in Example 1 except for the conditions. In Example 4, the number of layers was changed from Example 1 to four layers, and the absorption rate was calculated under the same conditions as in Example 1 except for the conditions. The calculation result of Example 3 is shown in FIG. 16, and the calculation result of Example 4 is shown in FIG. 17, respectively. Both FIGS. 16 and 17 show the calculation results of the absorption rate when the interlayer distance is changed. As can be seen from FIGS. 16 and 17, a structure in which the number of layers of the cloth is two or four layers provides a higher absorption rate than the single layer structure. However, when the number of layers is two, the maximum absorption rate remains less than 80%. From this, it is considered that a higher absorption rate can be obtained in a configuration in which the number of layers exceeds two.

(Consideration of each calculation result of Examples 1 to 4)
The calculation results of Examples 1 to 4 described above will be considered below. Specifically, the present invention will be compared with a system in which the absorption effects of cloth are simply added (hereinafter referred to as a simple addition system). The flow resistance of the cloth forming each layer was 400 Pa · s / m.
The simple addition system assumes an ideal system that absorbs the most as a superposition of a single-layer structure. Specifically, there is no sound interference between the cloths, and it hits the cloth of each layer. It was assumed that all of the sound that was not absorbed would pass through the cloth. That is, when the absorption rate of the cloth forming each layer is A, the transmittance is T, and the reflectance is R, the following equation holds in the simple addition system.
T = 1-A
R = 0
In the actual single-layer structure, a certain amount of reflection occurs, so that the absorption is smaller than that of the above ideal system.

Then, in the simple addition system, the absorption rate An of the entire soundproof structure in which the number of layers of the cloth is n (n is a natural number of 2 or more) is expressed as follows.
When n is 2: An = A {1+ (1-A)}
When n is 3 or more: An = A {1 + (1-A) + ... + (1-A) ^n-1 }
Incidentally, the absorption rate An when the number of layers is 1 (that is, a single layer structure) can be obtained by using the maximum absorption rate when actually calculated for one layer.

The absorption rate An of the simple addition system calculated by the above procedure is shown in FIG. Further, FIG. 18 also shows the calculation results when the maximum absorption rate in the soundproof structure of the present invention is calculated by changing the number of layers by the above-mentioned calculation of the multilayer structure using COMSOL.

As shown in FIG. 18, when the simple addition system and the soundproof structure of the present invention are compared, the absorption rate when the cloths are arranged at intervals of several mm as in the soundproof structure of the present invention is higher. , It is larger than the absorption rate of the simple addition system. That is, it was found that by arranging the cloths close to each other, an absorption rate higher than the ideal absorption in a simple addition system can be obtained. More specifically, the presence of flow resistors in close proximity to each other causes sound interference between the flow resistors. At this time, if the distance between the separated flow resistors, that is, the interlayer distance is shorter than 1/2 times the wavelength λ of the sound absorbing target sound (that is, λ / 2), due to the relationship of sound superposition due to interference. , The reflected waves from the two flow resistors cancel each other out. As a result, the amount of absorption increases. When the frequency of the sound to be absorbed is 12 kHz, λ / 2 is about 14 mm, so that the above-mentioned suitable interference condition is sufficiently satisfied if the interlayer distance is about several mm.
When the distance is λ / 2, as shown in the next Example 5, absorption is minimized due to the interference effect.
Therefore, according to the soundproof structure of the present invention, it is considered that a higher absorption rate can be obtained than when the arrangement is a simple addition system, for example, when the distance is large. That is, it was found that by arranging the flow resistors close to each other, not only the thickness of the entire soundproof structure is reduced, but also a high absorption effect can be obtained by using the sound interference effect.

(Example 5)
In Examples 1 to 4 above, the absorptivity was calculated by changing the interlayer distance, but under such conditions, as the number of layers formed by the cloth increases, the overall thickness increases. On the other hand, in Example 5, the total thickness was fixed at 20 mm, and the number of layers was changed from two layers to five layers to calculate the absorption rate. The flow resistance of the cloth was 400 Pa · s / m, and the other conditions were the same as in Simulation 1. The calculation result of Example 5 is shown in FIG.

When the number of layers is two, as shown in FIG. 19, since the interlayer distance is relatively large, the sound absorption fluctuates (waviness) due to the interference between the cloths. The wavelength λ of the sound having a frequency of 9 kHz is about 38 mm, and the interlayer distance is approximately λ / 2. When the number of layers is two, the absorption rate becomes extremely small at a frequency of 9 kHz, and wide-band absorption is not performed.
Further, under the condition that the number of layers is two and the interlayer distance is λ / 2, the reflected wave in each layer has a phase relationship in which the reflected waves are completely strengthened between the layers. Therefore, under the above conditions, the reflected wave in the soundproof structure is maximized, while the sound absorption rate in the soundproof structure is minimized. The minimum value of the absorption rate confirmed in FIG. 19 is caused by the above-mentioned strengthening of the reflected waves.
As described above, it is not preferable that the interlayer distance is λ / 2, and in particular, the above condition is satisfied in the region where the auditory sensitivity is high in the audible range (specifically, in the range of about 1 kHz to 4 kHz). Is not desirable.

On the other hand, it was found that in a structure with three or more layers, the absorption rate converges to a relatively high value. That is, the distance between the two outermost cloths is 20 mm as in the case where the number of layers is two, but the interlayer distance is λ / 2 due to the cloths being arranged between them. The sound is strengthened due to the interference at the time, and the reduction of absorption accompanying it is almost eliminated, and a wide band absorption effect can be obtained. It is considered that this is because the reflected waves from the middle layer of the three layers have a phase relationship in which they cancel each other out, so that the relationship in which the reflected sounds strengthen each other is broken.

From the above, by using a multi-layer structure with three or more layers, the maximum absorption rate can be increased, and the effect of reducing absorption (minimization effect) due to interference when the interlayer distance is λ / 2 can be suppressed. can. In this respect, a multi-layer structure having three or more layers is superior to a two-layer structure.

Further, as described above, when the interlayer distance is 1/2 times (λ / 2) the wavelength λ of the sound to be absorbed, the effect of reducing absorption due to interference (minimization effect) appears. This depends on the frequency of the sound to be absorbed, but for example, in order to sufficiently absorb a sound having a frequency of 8 kHz, it is not preferable that the interlayer distance is larger than 20 mm. Therefore, in order to suppress the effect of reducing absorption due to interference (minimization effect) in a structure in which cloths are multi-layered, it is desirable to design the interlayer distance, that is, the distance between separated cloths to be 20 mm or less.

(Example 6)
When the absorption rate of a thick single-layer structure is compared with the absorption rate of a two-layer structure having the same total thickness as the thickness, there is a total thickness in which the absorption rate of the latter is larger. It can be said that the total thickness at this time is the total thickness to which the multi-layer structure, which is a feature of the present invention, should be used because the two-layer structure is more dominant from the viewpoints of both absorption rate and weight.

Therefore, in Example 6, for each of the single-layer structure and the two-layer structure, the flow resistance of the cloth is set to a condition value (specifically, 800 Pa · s / m) at which the absorption rate in the single-layer structure becomes large. A simulation was performed. Explaining the single-layer structure of Example 6, the flow resistance of the cloth is 800 Pa · s / m (Rayls), the surface density is 200 g / m ² , and the thickness is changed from 1500 μm to 12000 μm (12 mm). Absorption rates were calculated respectively.

On the other hand, in the case of a two-layer structure, the flow resistance of the cloth forming each layer is 800 Pa · s / m, the surface density is 200 g / m ² , the thickness of each layer is 500 μm, and the interlayer distance changes from 500 μm to 11000 μm (11 mm). Then, the absorption rate was calculated respectively. Here, for example, when the thickness is 5000 μm in the single-layer structure and when the thickness of each layer (cloth) is 500 μm in the two-layer structure and the interlayer distance is 4000 μm, the thickness of the single-layer structure and the two Equal to the total thickness of the layer structure. Then, in Example 6, the absorption rate was compared when the thickness of the single-layer structure and the total thickness of the two-layer structure were equal. FIG. 20 shows the absorptivity spectra of each structure when the thickness of the single-layer structure and the total thickness of the two-layer structure are both 5000 μm. As shown in FIG. 20, in the other frequency bands except for a part of the frequency band on the low frequency side, the absorption rate of the two-layer structure becomes larger over the whole.

Hereinafter, the upper limit of the thickness of each layer (specifically, the flow resistor) in the multi-layer structure will be examined by comparing the two-layer structure and the single-layer structure.
The thicker the total thickness in the two-layer structure, the larger the interlayer distance can be. Within the range where the interlayer distance does not become excessively large, the absorption rate increases as the interlayer distance increases, and when the total thickness is increased, the absorption rate of the two-layer structure exceeds the absorption rate of the single-layer structure. .. In this regard, the frequencies were set to 1 kHz, 2 kHz, 4 kHz, 8 kHz, and 16 kHz according to the definition of the octave band, and the absorption rates of the single layer structure and the double layer structure were compared for each frequency. FIG. 21 shows, as an example, the result of comparing the relationship between the total thickness and the absorption rate at 2 kHz between the single-layer structure and the two-layer structure. As shown in FIG. 21, when the total thickness is 7000 μm (7 mm) or more, that is, when the interlayer distance is 6000 μm (6 mm) or more in the two-layer structure, the absorption rate of the two-layer structure is single even at 2 kHz. It exceeds the absorption rate of the layer structure. In this case, the total volume of the flow resistors is reduced to about 14% as compared with the single-layer structure, but the absorption rate is larger in the two-layer structure.
Table 3 shows the comparison results of the absorption rates at 2 kHz and other frequencies.

Here, it is examined whether it is more effective to arrange the flow resistors in a space having the same volume as a single layer or two layers. From FIG. 21 and Table 3, it can be seen that the absorption rate of the two-layer structure exceeds the absorption rate of the single-layer structure even if the volume is smaller as the frequency increases. When the absorption rate of the two-layer structure exceeds the absorption rate of the single-layer structure in the space of the same volume, the result is that it is preferable to arrange the two-layer structure in the space rather than the single-layer structure. From this result, the upper limit of the layer thickness can be determined. More specifically, from the above results, the thickness per layer is preferably less than 11 mm, more preferably less than 7 mm, even more preferably less than 4 mm, and more preferably 2.5 mm. It is more preferably less than, and particularly preferably less than 2 mm.
By arranging three or more layers of flow resistors in the above space, it is possible to further improve the absorption rate.

(Example 7)
In Example 7, the upper limit of the interlayer distance in the multilayer structure was examined from the condition of wideband sound absorption.
First, the flow resistance of the flow resistors forming each layer of the two-layer structure was 400 Pa · s / m, the surface density was 200 g / m ² , the thickness was 250 μm, and the interlayer distance was changed to calculate the absorption rate. FIG. 22 shows the relationship between the interlayer distance and the absorption rate for two types of frequencies, 4 kHz and 12 kHz. As shown in FIG. 22, it was found that the dependence of the absorptance rate on the interlayer distance changes depending on the frequency.

Next, in FIG. 23, the value obtained by dividing the interlayer distance L by the wavelength λ corresponding to the above frequency (4 kHz and 12 kHz) (value corresponding to the horizontal axis L / λ in the figure, and hereinafter, the standard). The absorption rate for the normalization distance) is shown. As can be seen from FIG. 23, the dependence of the absorptance rate on the normalized distance is completely the same at both of the two types of frequencies. That is, it was found that the absorptivity is maximized when the interlayer distance L is the distance corresponding to λ / 4, and is minimized when the distance is the distance corresponding to λ / 2. More precisely, when the interlayer distance L is (2m + 1) / 4 (m is an integer of 0 or more), the absorption rate becomes a maximum value, and when it becomes 2m × λ / 4, it becomes a minimum value.

Further, as can be seen from FIG. 23, when the interlayer distance L is 0, the absorption rate becomes the minimum at all frequencies. Further, when the layers are separated from each other, the wavelength becomes shorter as the frequency of the sound becomes higher, so that it can be seen that the absorption rate vibrates between the maximum value and the minimum value from the stage where the interlayer distance L is small. The dependence of this absorption rate on the normalized distance can be well expressed by the curve shown by the following equation.
Y = a + b × {sin (L / (λ / 4) × Pi / 2)} ^ 2
In the above equation, Y is the absorptivity, L is the interlayer distance, a and b are constants, the constant a is 0.5, and the constant b is 0.3.
Here, the wave phenomenon shows the dependence of the sin function, and the absorption of sound is expressed by energy. Considering this, it is physically natural that the sound absorption rate is dependent on the square of the sin function as shown in the above equation.

By the way, the soundproof structure of the present invention is intended to absorb the sound heard by humans in a wide band. Therefore, in Example 7, the interlayer distance that increases the absorptivity over many frequencies was calculated. Specifically, the frequency of the sound to be absorbed was set to 500 Hz to 16000 Hz in the 1/3 octave band. Further, assuming the above-mentioned two-layer structure, the function for determining the interference component of the absorption rate is defined as the Absorption Function (AF) represented by the following equation.
AF = {Aweighting x sin (L / (λ / 4) x Pi / 2)} ^ 2
According to the above function, it is possible to calculate the effect of increasing or decreasing the absorption rate due to the interference of sound between layers. A-weighting is the weighting of the A characteristic defined in IEC (International Electrotechnical Commission) 61672-1: 2013. More specifically, Aweighting is a weighting calculated from a loudness curve showing a weighting for a frequency at which a human feels May cry, and is multiplied by a sound pressure for each frequency. By multiplying this weighting by the sound pressure of each frequency, it is possible to evaluate the absorption rate, reflecting, for example, that a sound of about 1 kHz to 4 kHz is the most audible sound for humans.

In Example 7, the Absorption Function at each frequency is expressed as AF (f), and by adding them over all frequencies, the absorption rate over a wide band frequency (strictly speaking, the absorption rate perceived by humans). Was evaluated. As a result, FIG. 24 shows a graph showing the dependence of the total value of AF (f) (hereinafter, total absorption value) on the interlayer distance. As shown in FIG. 24, it can be seen that as the interlayer distance is increased, the total absorption value showing the absorption characteristics tends to saturate and vibrate. In the region where the total absorption value vibrates, it is shown that the absorption rate does not increase even if the interlayer distance is increased (that is, even if the size of the entire two-layer structure is increased). Therefore, in the above region, it can be seen that it is necessary to take measures such as sandwiching a new third layer flow resistor (cloth) between the layers.
From the above, it is preferable that the interlayer distance is not more than the size corresponding to the above-mentioned vibration region.

Further, in order to evaluate the increase / decrease in the absorption rate with respect to the interlayer distance, the total absorption value shown in FIG. 24 is differentiated by the interlayer distance, and the result is shown in FIG. 25. As shown in FIG. 25, in a region where the interlayer distance is 1 to 5 mm, the above differential value increases as the interlayer distance increases. Therefore, a soundproof structure (two-layer structure) should be constructed by separating the layers by about 5 mm. It can be seen that sound can be absorbed efficiently. Further, in the region where the interlayer distance is 6 mm to 30 mm, the differential value decreases monotonically, but the differential value becomes a positive region. In this region, the total absorption value increases as the interlayer distance increases, but it can be seen that the amount of increase decreases as the interlayer distance increases. Further, when the interlayer distance is 30 mm or more, it becomes the above-mentioned vibration region. In particular, the differential value becomes negative in the region where the interlayer distance is 40 mm or more. That is, in this region, the total absorption value becomes small even if the interlayer distance is increased, and the absorption rate is hardly increased even if the interlayer distance is increased. Therefore, when the layers are arranged at a distance of 40 mm or more, an additional layer (that is, another cloth) should be inserted between them.

As described above, considering the results shown in FIG. 25, the interlayer distance is preferably less than 40 mm, more preferably 30 mm or less, and at 20 mm or less, which is the inflection point of the differential value. It is especially desirable to have. Further, in the case of increasing the absorption rate most efficiently according to the interlayer distance, the vicinity of 5 mm is particularly preferable, and based on this point, the interlayer distance is 1 mm or more and 12 mm or less (12 mm is an inflection of the above differential value). Point) is the most desirable.

Each of Examples 1 to 8 of the present invention described above is within the scope of the present invention, and the effect of the present invention is clear.

10, 10x, 10y Soundproof structure 11 String 12 Flow resistor 12a Specific flow resistor 14 Holding member 16 Strut 110, 110x, 210 Louver 211 Plate material B Soundproof panel Bx Panel body By Frame C Ceiling D Duct R Air supply fan V booth

Claims (11)

Has multiple flow resistors arranged side by side,
Of the plurality of flow resistors, two adjacent flow resistors face each other in the thickness direction of each of the two adjacent flow resistors.
The plurality of flow resistors include two or more specific flow resistors having a flow resistance of 150 Pa · s / m or more and 2050 Pa · s / m or less.
The thickness of the specific flow resistor is less than 11 mm.
A gap is provided between the adjacent specific flow resistors.
The average value of the thickness of each portion of the gap is 0.6 mm or more and 20 mm or less .
The soundproof structure is characterized in that the plurality of flow resistors include 3 or more and 10 or less of the specific flow resistors . The soundproof structure according to claim 1, wherein the specific flow resistor is made of cloth. The soundproof structure according to claim 1 or 2 , wherein the specific flow resistors having 3 or more and 10 or less are continuously arranged in the direction in which the plurality of flow resistors are arranged. The soundproof structure according to any one of claims 1 to 3 , wherein each of the plurality of flow resistors is the specific flow resistor. The soundproof structure according to any one of claims 1 to 4 , wherein the average value is 1 mm or more and 12 mm or less. The soundproof structure according to any one of claims 1 to 5 , wherein the thickness of the specific flow resistor is less than 4 mm. The soundproof structure according to any one of claims 1 to 6 , wherein a holding member for holding the gap is provided between the adjacent specific flow resistors. The soundproof structure according to any one of claims 1 to 7 , wherein the flow resistance of the specific flow resistor is 200 Pa · s / m or more and 1300 Pa · s / m or less. The soundproof structure according to any one of claims 1 to 8 , wherein the soundproof structure is attached to at least one of a ceiling and a wall partitioning a space in a suspended state. A soundproof panel having the soundproof structure according to any one of claims 1 to 9 . A louver in which the soundproof structure according to any one of claims 1 to 10 constitutes at least a part thereof.

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