JPWO2019138969A1 - Soundproof box - Google Patents

Abstract

The soundproof box has a plurality of soundproof walls having a soundproof structure having a honeycomb core, a first surface plate sandwiching the honeycomb core, a second surface plate, and a through hole formed in the first surface plate. The plurality of soundproof walls have two or more types of soundproof walls having soundproof structures having different frequency characteristics from each other. This soundproof box is thin and lightweight, and can realize high rigidity and wideband soundproofing.

Description

The present invention relates to a soundproof box, and more specifically, at least two or more kinds of soundproof walls having different frequency characteristics, including a soundproof wall having a soundproof structure having a through hole in one of two surface plates sandwiching a honeycomb core. Regarding the soundproof box used.

Boxes that use honeycomb boards as wall materials are lightweight and highly rigid, so they are used as soundproof boxes that can be easily installed. However, if the sound absorbing material is not placed inside the box, there is a problem that the reverberation inside the box becomes large and the sound reflected inside leaks out of the box, so that the soundproofing performance of the box deteriorates. ..
On the other hand, when the sound absorbing material is arranged on the wall of the box, it is necessary to arrange a thick sound absorbing body in order to enhance the sound absorbing effect. Therefore, the soundproofing property of the soundproof box is improved, but the volume inside the box is reduced.
Therefore, the wall of such a box is composed of a honeycomb structure, and one surface plate of the surface plate covering both sides of the honeycomb core is made of a porous material (see Patent Document 1), or a plurality of surface plates. A perforated surface plate having through holes is provided, and a sound absorbing material and / or a sound insulating material is provided on the perforated surface plate (see Patent Documents 2, 3 and 4), or the honeycomb core has a multilayer structure between them. By arranging the internal perforated plate (see Patent Document 5), the weight is reduced as compared with the conventional case, and the soundproofing performance such as the sound absorption coefficient is improved.

For example, Patent Document 1 proposes a sound absorbing body in which a porous material made of a paper material having a predetermined porosity is arranged on a honeycomb utilizing Helmholtz resonance of the honeycomb.
Patent Document 2 proposes to form a Helmholtz sound absorbing structure by forming a fine through hole corresponding to a honeycomb cell in a surface plate adhered on a honeycomb, and further joining a non-woven fabric to the upper surface thereof. With this structure, a sound absorbing effect can be added while maintaining high rigidity, and the sound absorbing frequency band can be widened by using a non-woven fabric.

Also in Patent Documents 3 and 4, a sound absorbing structure is formed by forming a fine through hole corresponding to a honeycomb cell in a surface plate adhered on a honeycomb, and a sound absorbing material and / or a sound insulating material is provided on the upper surface thereof. Is proposing. With this structure, the sound insulation effect can be enhanced while maintaining high rigidity, and the sound insulation effect can be further enhanced by the sound absorbing material and / or the sound insulating material.
In Patent Document 5, the honeycomb core between the perforated front plate and the back plate has a one-layer structure in the peripheral portion and a multi-layer structure in the inner portion, and as a partition panel in which one or more internal perforated plates are arranged between them, the sound insulation performance is improved. , The reverberation time in the room can be optimized. Further, in Patent Document 5, by setting the aperture ratio of the perforated surface plate and the inner perforated plate to be gradually reduced, the number of resonance frequencies that can be absorbed by the Helmholtz resonance principle increases, so that a wide band sound is absorbed. be able to.

Japanese Unexamined Patent Publication No. 09-228506 Japanese Unexamined Patent Publication No. 2017-065026 Japanese Unexamined Patent Publication No. 09-221849 JP-A-2017-151256 Japanese Patent No. 5531343

By the way, in the sound absorbing structure disclosed in Patent Document 1, there is a problem that the rigidity of the board is lowered if a porous material made of a paper material is arranged directly above the honeycomb.
Further, in the soundproof structure disclosed in Patent Document 2, the sound absorption frequency band is widened by the non-woven fabric, but there is a problem that there is a limit.
Further, even in the sound absorbing structures disclosed in Patent Documents 3 and 4, the frequency band capable of soundproofing is narrow because resonance is used, and the sound absorbing material and / or the sound insulating material further improves the sound insulating effect and widens the sound absorbing frequency band. However, there was a problem that there was a limit.

Further, in the partition panel disclosed in Patent Document 5, in order to widen the soundproof band, sound absorbing films having different frequency characteristics are arranged in the honeycomb thickness direction to realize a wide band. However, this method has problems such as a thick wall, an increase in weight, and a complicated structure, which makes it difficult to manufacture.
Further, the sound absorbing structures disclosed in Patent Documents 1, 2 and 5 have a problem that the frequency band capable of soundproofing is narrow because Helmholtz resonance is used.
That is, since the sound absorbing structures disclosed in Patent Documents 1 to 5 cannot realize thinness, light weight, high rigidity, and wideband soundproofing, even when they are used for the soundproofing wall of the soundproofing box, they are thin. There is a problem that it is not possible to realize a soundproof box that is lightweight, has high rigidity, and can provide soundproofing over a wide band.

An object of the present invention is to solve the above-mentioned problems of the prior art, and at least two types having a soundproof structure having different frequency characteristics including a soundproof wall having a soundproof structure having a through hole in one of two surface plates sandwiching the honeycomb core. It is an object of the present invention to provide a soundproof box that is thin, lightweight, has high rigidity, and can realize wideband soundproofing by being used for the above soundproof wall.

Here, in the present invention, "soundproofing" includes both meanings of "sound insulation" and "sound absorption" as acoustic characteristics, and particularly refers to "sound insulation". In addition, "sound insulation" means "shielding sound". That is, "sound insulation" means "not transmitting sound". Therefore, "sound insulation" includes "reflecting" sound (reflection of sound) and "absorbing" sound (absorption of sound) (Sanshodou Daijirin (3rd edition), and Nippon Onkyo. See http://www.onzai.or.jp/question/soundproof.html and http://www.onzai.or.jp/pdf/new/gijutsu201312_3.pdf on the Materials Society web page).
In the following, basically, "reflection" and "absorption" are not distinguished, but are referred to as "sound insulation" and "shielding" including both, and when distinguishing between the two, they are referred to as "reflection" and "absorption". ..

In order to achieve the above object, the soundproof box according to the present invention has a honeycomb core, a first surface plate sandwiching the honeycomb core, a second surface plate, and a through hole formed in the first surface plate. It has a plurality of soundproof walls having a soundproof structure, and the plurality of soundproof walls have two or more types of soundproof walls having soundproof structures having different frequency characteristics from each other.

Here, it is preferable that two types of soundproof walls out of two or more types of soundproof walls are arranged so as to face each other.
Further, it is preferable that two more types of soundproof walls among the two or more types of soundproof walls are arranged so as to face each other.
Further, the soundproof structure preferably has a sound absorbing body arranged on a part or the entire surface of at least one surface of the first surface plate.
Further, it is preferable that the soundproof wall having a soundproof structure having a sound absorbing body and the soundproof wall having a soundproof structure excluding the sound absorbing body are arranged to face each other.

Further, the first surface plate having a soundproof structure preferably has through holes having different diameters.
Further, the soundproof structure constitutes a Helmholtz resonator by a through hole having at least one diameter of through holes having different diameters of the first surface plate, one space surrounded by the inner surface of the honeycomb core, and the second surface plate. It is preferable that it is a thing.
Further, in the soundproof structure, the air column resonator is composed of a through hole having at least one diameter of the through holes having different diameters of the first surface plate, one space surrounded by the inner surface of the honeycomb core, and the second surface plate. It is preferable that the material is used.
Further, the honeycomb core is preferably made of paper, metal, or resin.
The second surface plate is preferably made of paper, metal, or resin.
Further, the first surface plate is preferably made of paper, metal, or resin.
Also, when two types of soundproof walls out of two or more types of soundproof walls are arranged facing each other and are paired, they have sound absorption peaks at different frequencies with respect to the frequency characteristics of the paired soundproof walls. In a pair of soundproof walls, among the frequencies at which the sound absorption coefficient of the soundproof wall having a low frequency absorption peak (f1) is 10%, the frequency on the high frequency side (f2) is equal to or lower than the high frequency absorption peak frequency (f3). Moreover, it is preferable that the sound absorption coefficient of the soundproof wall having this absorption peak is equal to or higher than the frequency (f4) on the low frequency side among the frequencies at 10%.

The diameter of the through hole is preferably 1.0 mm or more, and the opening ratio of the through hole in the first surface plate is preferably 1.0% or more.
The thickness of the sound absorbing body is preferably 50 mm or less.
Further, the sound absorbing body is preferably made of a fine through-hole plate, a woven cloth, a knitted fabric, or a non-woven fabric.
Further, it is preferable that the fine through-hole plate penetrates in the thickness direction and has a plurality of fine through holes having a diameter of 1 μm to 250 μm.
Further, the material of the fine through-hole plate is preferably a flame-retardant material.
Further, the flame retardant material is preferably a metal.
The metal is preferably aluminum or an aluminum alloy.
Further, the sound absorbing body preferably has a deodorizing function.
Further, it is preferable that the sound absorbing body is arranged only on one surface of the first surface plate located on the honeycomb core side.
Further, it is preferable that the sound absorbers are arranged on both surfaces of the first surface plate.

According to the present invention, it is made thinner by using it for at least two or more types of soundproof walls having different frequency characteristics, including a soundproof wall having a soundproof structure having a through hole in one of two surface plates sandwiching the honeycomb core. It is lightweight, has high rigidity, and can achieve wideband soundproofing.

It is a perspective view which shows typically an example of the soundproof box which concerns on one Embodiment of this invention. It is sectional drawing which shows typically an example of the soundproofing box shown in FIG. It is a perspective view which shows typically an example of the soundproof box which concerns on other embodiment of this invention. It is a partial cross-sectional view which shows typically an example of the soundproof structure used as a soundproof wall in the soundproof box of this invention. It is a top view which shows typically by partially breaking the soundproof structure shown in FIG. It is a partial sectional view schematically showing another example of the soundproof structure used as a soundproof wall in the soundproof box of this invention. It is a top view which shows typically by partially breaking the soundproof structure shown in FIG. It is a partial sectional view schematically showing another example of the soundproof structure used as a soundproof wall in the soundproof box of this invention. It is sectional drawing which shows typically an example of the Helmholtz resonator used in this invention. It is a graph which shows the aperture ratio dependence of the vertical incident sound absorption coefficient of the Helmholtz resonator shown in FIG. It is a graph which shows the spectrum of the sound pressure of the Helmholtz resonator shown in FIG. It is a graph which shows the noise level with respect to the aperture ratio of the Helmholtz resonator shown in FIG. It is a partial sectional view schematically showing another example of the soundproof structure used as a soundproof wall in the soundproof box of this invention. It is a partial sectional view schematically showing another example of the soundproof structure used as a soundproof wall in the soundproof box of this invention. It is a graph which shows the relationship of the different frequency characteristics of the soundproof wall which makes a pair of the soundproof box of this invention. It is a graph which shows the relationship between the vertical incident sound absorption coefficient and the frequency of four kinds of soundproof structures used for the soundproof wall of the soundproof box of this invention. It is a perspective view which shows typically an example of the acoustic measurement system of the soundproof box of Example 1 and Comparative Examples 1 to 3 of this invention. It is a graph which shows the noise level outside the soundproof box of Example 1 and Comparative Examples 1 to 3 of this invention. It is a graph which shows the noise level inside the soundproof box of Example 1 and Comparative Examples 1 to 3 of this invention.

Hereinafter, the soundproof box according to the present invention will be described in detail based on the preferred embodiments shown in the accompanying drawings.
The description of the constituent elements described below may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.
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.

[Soundproof box]
The soundproof box according to the present invention has a plurality of soundproof walls having a soundproof structure having a honeycomb core, a first surface plate sandwiching the honeycomb core, a second surface plate, and a through hole formed in the first surface plate. The plurality of soundproof walls are soundproof boxes having two or more types of soundproof walls having soundproof structures having different frequency characteristics from each other.
The soundproof box according to the present invention uses at least two or more types of soundproof walls having different frequency characteristics, including a soundproof wall having a soundproof structure having a through hole in one of the two surface plates sandwiching the honeycomb core. It is thin, lightweight, and can achieve high rigidity and wideband soundproofing.
The soundproof box according to the present invention can be configured as a soundproof box capable of wideband soundproofing with a simple box configuration by enhancing the sound absorbing performance of the soundproof wall.

The soundproof box of the present invention can also be used as, for example, a soundproof hut for pets such as a kennel, a soundproof box for covering a device (generator, PC) that becomes a noise source, or a soundproof room for humans. When the noise source requires intake and exhaust, the soundproof structure on any surface of the soundproof box may be provided with an opening for intake and an opening for exhaust, although not shown.
Further, the soundproof box of the present invention is usually preferably one in which a soundproof wall is used on the entire surface of a polyhedron such as a rectangular parallelepiped, or the entire surface other than one surface, but the present invention is not limited to this, and the polyhedron is not limited thereto. It may be a tubular body having a soundproof enclosure structure in which a soundproof wall is used on the entire surface other than the two opposing surfaces.
Therefore, the soundproof box of the present invention has a box-shaped interior (side walls, ceiling, floor, etc. excluding windows) inside a building or other building structure (for example, a house, a hall, an elevator, a music classroom, a conference room, etc.). It can be used for construction applications such as covering panel materials, transportation applications such as automobile interiors, and logistics applications such as box materials and packing materials.

In addition, the soundproof structure of the present invention can be used for copiers, blowers, air conditioners, ventilation fans, pumps, generators, ducts and the like.
In addition, the soundproof structure of the present invention also includes coating machines such as factories, industrial equipment such as various types of manufacturing equipment that emit sound such as rotary machines and conveyors, vehicles such as automobiles and trains, and vehicles such as automobiles and trains. , Transportation equipment such as aircraft, refrigerators, washing machines, dryers, televisions, copiers, microwave ovens, game machines, air conditioners, electric fans, PCs (personal computers), vacuum cleaners, air purifiers, ventilation fans, etc. It can be used for general household equipment and the like.
The soundproof box of the present invention is appropriately arranged at a position where the sound generated from the noise source passes in these various devices.

The soundproof box according to the present invention will be described in detail with reference to FIGS. 1 and 2.
FIG. 1 is a perspective view schematically showing an example of a soundproof box according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the soundproof box shown in FIG.
As shown in FIGS. 1 and 2, the soundproof box 30 of the present invention has a rectangular parallelepiped shape, and among the six surfaces thereof, the soundproof wall 32 on the right side in FIG. 1 and the soundproof wall 32 are arranged to face each other. The soundproof wall 34 on the left side in FIG. 1 and the four soundproof walls 36 on the front side in the middle of FIG. 1, the back side in the middle of FIG. 1, the upper side (ceiling) in the middle of FIG. 1, and the lower side (bottom surface) of FIG. Has.
Here, the soundproof wall 32 has the soundproof structure 10 required for the present invention, and the soundproof wall 34 has the soundproof structure 10A required for the present invention. The soundproof structure 10 of the soundproof wall 32 and the soundproof structure 10A of the soundproof wall 34 will be described in detail later, but as shown in FIG. 2, both have a honeycomb core 12 and a through hole 18 sandwiching the honeycomb core 12. Although it has one surface plate 16 and a second surface plate 20 having no through hole, the soundproof structure 10A further has a sound absorbing body 22, and therefore has different frequency characteristics from each other.

The remaining four soundproof walls 36 both have a soundproof structure 11 that can be used in the present invention. The soundproof structure 11 has a honeycomb core 12 and two second surface plates 20 having no through holes sandwiching the honeycomb core 12, as shown in FIG. 2, and has a soundproof structure 11. It has different frequency characteristics from 10 and 10A.
In the soundproof box 30 of the present invention, as shown in FIGS. 1 and 2, the soundproof structure 10 having different frequency characteristics and the two types of soundproof walls 32 and 34 having 10A are arranged to face each other. It is preferable that it is. However, the present invention is not limited to this, and may not be arranged facing each other. For example, in the example shown in FIG. 1, one of the four soundproof walls 36 may be replaced with the soundproof wall 34.

Further, the soundproof box 30 shown in FIGS. 1 and 2 has a pair of soundproof structures 10 having different frequency characteristics and two types of soundproof walls 32 and 34 having 10A. The invention is not limited to this, and may have two or more pairs. That is, it is preferable to increase the number of pairs of soundproof walls in which soundproof structures having different sound absorption characteristics are arranged, such as 2 pairs and 3 pairs, because the soundproof effect is enhanced.
For example, as in the soundproof box 30A shown in FIG. 3, in addition to the two types of soundproof walls 32 and 34 arranged facing each other, the two types of soundproof walls 32a and 34 arranged facing each other It may have three sets of 34a and two types of soundproof walls 32b and 34b arranged opposite to each other. In the example shown in FIG. 3, the soundproof walls 32a and 32b have a soundproof structure 10, and the soundproof walls 34a and 34b have a soundproof structure 10A.
In the soundproof box 30A shown in FIG. 3, three pairs of soundproof walls made of honeycomb cores having different sound absorption characteristics are arranged. In the soundproof box 30A, all three dimensions in the soundproof box can correspond to the mode by making such a form.

The soundproof boxes 30 and 30A shown in FIGS. 1 and 3 are composed of two types of soundproof walls 32, 34, 32a, and 34a, and 32b, 34b, but the present invention is limited thereto. Not done. The soundproof box of the present invention may have two or more types of soundproof walls having soundproof structures having different frequency characteristics, and may not be arranged facing each other. For example, it has three types of soundproof walls, which are the soundproof walls 32 and 34 having the soundproof structures 10 and 10A, and the soundproof walls having the soundproof structure 10B (see FIG. 8) required for the present invention, which will be described later. Is also good. Further, in the present invention, soundproof structures having different frequency characteristics may be used. Therefore, in each of the soundproof structures having the same structure, for example, the soundproof structures 10, 10A, and 10B, the through hole 18 of the first surface plate 16 is formed. The diameters may be different, the size of the honeycomb core 12 may be different, or the sound absorbing body 22 may be different.

By the way, since the low frequency sound has a long wavelength, it easily interferes in the soundproof box and forms a mode. Therefore, it tends to leak out of the soundproof box. Like the soundproof boxes 30 and 30A shown in FIGS. 1 and 3, modes are formed between paired soundproof walls in a box consisting of 6 faces (face-to-face parallel), and there are roughly 3 modes. Therefore, in order to soundproof each mode at various frequencies, the frequencies of at least one pair of soundproof walls (soundproof members) of the soundproof walls facing each other, such as the soundproof boxes 30 and 30A shown in FIGS. 1 and 3. It is desirable that the characteristics are different.
Further, in the soundproof box of the present invention, it is preferable that these soundproof walls have a mechanism that can be attached to and detached from each other. By doing so, it is possible to easily combine different types of soundproof walls to provide soundproofing in various modes. That is, it is preferable to provide a detachable mechanism that allows the soundproof wall to be easily removed, so that various soundproof walls can be easily combined.

[Soundproof structure]
The soundproof structure required for the soundproof box of the present invention will be described in detail with reference to FIGS. 4 to 8.
FIG. 4 is a cross-sectional view schematically showing an example of a soundproof structure used in the soundproof box of the present invention. FIG. 5 is a top view schematically showing the soundproof structure shown in FIG. 4 with a partial breakage. FIG. 6 is a cross-sectional view schematically showing another example of the soundproof structure used in the soundproof box of the present invention. FIG. 7 is a top view schematically showing the soundproof structure shown in FIG. 6 with a partial breakage. FIG. 8 is a cross-sectional view schematically showing another example of the soundproof structure used in the soundproof box of the present invention.
The soundproof structure 10 shown in FIGS. 4 and 5 has a honeycomb core 12 having a plurality of openings 14, a plate-shaped first surface plate 16 having a plurality of through holes 18, and a second surface plate 20. ..
On the other hand, the soundproof structure 10A shown in FIGS. 6 and 7 includes a honeycomb core 12 having a plurality of openings 14, a plate-shaped first surface plate 16 having a plurality of through holes 18, and a second surface plate 20. It has a sound absorbing body 22 and. That is, the soundproof structure 10A shown in FIGS. 6 and 7 has a sound absorbing body 22 between the first surface plate 16 and the honeycomb core 12 in the soundproof structure 10 shown in FIGS. 4 and 5.
Therefore, first, the soundproof structure 10A shown in FIGS. 6 and 7 will be described, and then the soundproof structure 10 shown in FIGS. 4 and 5 will be described.

The soundproof structure 10A shown in FIGS. 6 and 7 is used for the soundproof boxes 30 and 30A shown in FIGS. 1 and 3. As described above, the soundproof structure 10A includes a honeycomb core 12 having a plurality of openings 14, a plate-shaped first surface plate 16 having a plurality of through holes 18, a second surface plate 20, a sound absorbing body 22 and the like. Has.
Here, the first surface plate 16 and the second surface plate 20 are arranged so as to sandwich the honeycomb core 12 at intervals from each other. The first surface plate 16 is joined to one surface of the honeycomb core 12 via a sound absorbing body 22. The second surface plate 20 is joined to the other surface of the honeycomb core 12. That is, the sound absorbing body 22 is arranged between the first surface plate 16 and the honeycomb core 12 (that is, one surface of the first surface plate located on the honeycomb core side). In the example shown in FIG. 6, the sound absorbing body 22 is composed of a fine through hole plate 26 having a plurality of fine through holes 24.
In addition, in FIG. 7, in order to make it easy to understand the structure of the soundproof structure 10A, the portion where the first surface plate 16 and the sound absorbing body 22 (fine through-hole plate 26) are broken is shown on the left side of FIG. The portion where only the face plate 16 is broken is shown in the middle of FIG.

[Honeycomb core]
The honeycomb core 12 is arranged between the first surface plate 16 and the second surface plate 20, is a frame body having a plurality of honeycomb cells (frames), and has a plurality of openings 14 penetrating in the thickness direction. Has. That is, each honeycomb cell (frame) has an opening 14.
The plurality of openings 14 of the honeycomb core 12 are closed by the first surface plate 16 and the sound absorbing body 22 arranged on both sides, and the second surface plate 20. Behind the through hole 18 of the first surface plate 16 and the fine through hole 24 of the fine through hole plate 26 which is the sound absorbing body 22, the opening 14 of the honeycomb core 12 is a closed space, and a back air layer is formed.
Here, a plurality of through holes 18 are arranged with respect to the first surface plate 16 so that one through hole 18 of the first surface plate 16 corresponds to one opening 14 of the honeycomb core 12. Is preferable. Therefore, it is preferable that the plurality of through holes 18 of the first surface plate 16 are arranged corresponding to the plurality of openings 14 of the honeycomb core 12, respectively. When the plurality of openings 14 of the honeycomb core 12 are regularly arranged, the plurality of through holes 18 are also regularly arranged in the first surface plate 16 according to the regular arrangement of the plurality of openings 14. Of course.

The arrangement of the plurality of openings 14 of the honeycomb core 12 and the arrangement of the plurality of through holes 18 of the first surface plate 16 are not limited to those described above. Two or more through holes 18 of the first surface plate 16 may be arranged so as to correspond to the opening 14 of the honeycomb core 12. Further, the plurality of openings 14 do not have to be regularly arranged in the honeycomb core 12.
Further, the honeycomb core 12 preferably has a honeycomb structure. That is, the shape of the opening 14 is preferably a honeycomb (regular hexagon) shape in the plane shape, but is not particularly limited in the present invention. For example, the shape of the opening 14 is a circular, oval, square (regular quadrangle), rectangle, diamond, or other quadrangle such as a parallel quadrilateral, a regular triangle, an isosceles triangle, or a triangle such as a right triangle, a regular pentagon, Alternatively, it may be a polygon including a regular polygon such as a regular octagon, an elliptical shape, or the like, or an indefinite shape. When the shape of the opening 14 is a regular polygon such as a circle or a square, the diameter (hole diameter or size) of the opening 14 is defined as the distance between opposite sides passing through the center or the diameter equivalent to a circle. In the case of polygons, ellipses, or irregular shapes, it can be defined as the equivalent diameter of a circle. In the present invention, the circle-equivalent diameter and radius are the diameter and radius when converted into circles having the same area, respectively.

Here, as shown in FIG. 6, the diameter (size) of the opening 14 of the honeycomb core 12 is larger than the diameter of the through hole 18 of the first surface plate 16. The diameter of the opening 14 can be said to be the size (for example, width or length) of the honeycomb cell of the honeycomb core 12.
The diameter of the opening 14 is preferably 1.0 mm to 500 mm, more preferably 5 mm to 250 mm, and particularly preferably 10 mm to 100 mm.
Here, the reason why the diameter of the opening 14 is preferably 1.0 mm to 500 mm is that when it is smaller than 1.0 mm, the air viscous resistance in the side wall of the tubular honeycomb core becomes high, and the sound absorbing effect is lowered. Also, it becomes difficult to manufacture. Further, if the size is larger than 500 mm, the rigidity is lowered.
Further, the opening ratio of the opening 14 of the honeycomb core 12 is larger than the opening ratio of the through hole 18 of the first surface plate 16.
The shape and / or diameter of the opening 14 (or honeycomb cell) may be the same and constant in all the openings 14 (or honeycomb cell), but may be different and different sizes (or honeycomb cells). The opening (frame, honeycomb cell) of the opening (including the case where the shape is different) may be included.
The planar shape and size (planar size) of the honeycomb core 12 are not particularly limited, and may be appropriately determined according to the planar shape and size of the first surface plate 16 or the second surface plate 20. You just have to choose.

The thickness of the honeycomb core 12 is equal to the distance (separation distance) between the sound absorbing body 22 and the second surface plate 20, but since the thickness of the sound absorbing body 22 is thin, the first surface plate 16 and the second surface plate 20 It can be said that it is almost equal to the interval (separation distance) between. The thickness of the honeycomb core 12 is not particularly limited, and may be determined or selected according to the place where the soundproof structure 10A of the present invention is used and the environment. The thickness of the honeycomb core 12 is, for example, preferably 1.0 mm to 200 mm, more preferably 5 mm to 100 mm, and particularly preferably 10 mm to 50 mm.
Here, the reason why the thickness of the honeycomb core 12 is preferably 1.0 mm to 200 mm is that the rigidity is greatly reduced when it is less than 1.0 mm, and the soundproof structure becomes thicker when it is more than 200 mm, and each application. This is because the arrangement space is exhausted.

Further, as a material of the honeycomb core 12, it is lightweight and has high rigidity, and the honeycomb core 12 can support the first surface plate 16 and the sound absorbing body 22, and is between the sound absorbing body 22 and the second surface plate 20. It is not particularly limited as long as the interval can be maintained constant and the air column resonance structure can be formed together with the first surface plate 16, the sound absorbing body 22, and the second surface plate 20. The material of the honeycomb core 12 may be, for example, a flammable material or a flame-retardant material.
In the present invention, the flammable material refers to a material other than the following flame-retardant materials, and examples thereof include resin materials such as paper, wood, and synthetic resin. Examples of paper include corrugated cardboard and boards.
Examples of the resin material include acrylic resins such as polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polycarbonate, polyamideide, polyarylate, polyetherimide, polyacetal, polyetheretherketone, polyphenylene sulfide, polysulfone, and poly. Butylene terephthalate, polyimide, triacetyl cellulose and the like can be mentioned.

In the present invention, the flame-retardant material refers to a material other than the above-mentioned flammable material, but in the case of a building material, a non-combustible material specified in Article 2, Item 9 of the Building Standards Act, Article 1 of the Building Standards Act Enforcement Ordinance. Refers to the semi-incombustible material specified in item 5 and the flame-retardant material specified in Article 1, item 6 of the same. These materials do not burn for more than 5 minutes after the start of heating when heated by a normal fire, do not cause harmful deformation, melting, cracking, and other damage for fire prevention, and are harmful for evacuation. It is necessary to satisfy the three points of not generating smoke or gas.
Examples of the flame-retardant material include materials such as metal materials, inorganic materials, flame-retardant plywood, flame-retardant fiberboard, and flame-retardant plastic plates. Examples of the metal material include aluminum, steel, titanium, magnesium, tungsten, iron, steel, chromium, chromium molybdenum, dichrome 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.

In addition, as the material of the honeycomb core 12, a material containing carbon fibers such as carbon fiber reinforced plastic (CFRP), carbon fiber, and glass fiber reinforced plastic (GFRP) can be mentioned.
In addition, a plurality of kinds of materials of these honeycomb cores 12 may be used in combination.
As the material of the honeycomb core 12, it is preferable to use a metal such as aluminum because nonflammability can be imparted and high fire resistance can be obtained. It is preferable to use a metal or resin as the material of the honeycomb core 12 because the rigidity is increased.
On the other hand, it is preferable to use paper as the material of the honeycomb core 12 because it can be easily incinerated, easily disposed of, and made lighter.
Further, it is preferable to use a paper coated with an aramid resin because it is lightweight and can obtain fire resistance.
From the above, the honeycomb core 12 is preferably made of paper, metal, or resin.
Here, regarding the thickness of the material of the honeycomb core 12, the honeycomb core 12 is lightweight and has high rigidity, and has rigidity capable of supporting the first surface plate 16 and the sound absorbing body 22, and the sound absorbing body 22 and the second table. It is not particularly limited as long as the distance between the face plate 20 and the honeycomb core 12 can be maintained constant and the honeycomb core 12 can form an air column resonance structure together with the second surface plate 20. The thickness of the material of the honeycomb core 12 is, for example, preferably 0.001 mm (1 μm) to 5 mm, more preferably 0.01 mm (10 μm) to 2 mm, and 0.1 (100 μm) mm to 1 mm. It is particularly preferable to have.
Here, the reason why the thickness of the material of the honeycomb core 12 is preferably 0.001 mm (1 μm) to 5 mm is that the rigidity decreases when it is less than 0.001 mm (1 μm). This is because if it exceeds 5 mm, the weight becomes heavy and the lightweight merit of the honeycomb disappears.

It is preferable that the sound absorbing body 22 and the honeycomb core 12 and the honeycomb core 12 and the second surface plate 20 are fixed without a gap. The method of fixing the sound absorbing body 22 and the honeycomb core 12 and the method of fixing the honeycomb core 12 and the second surface plate 20 are as long as the honeycomb core 12, the sound absorbing body 22 and the second surface plate 20 can be fixed. But it's fine, not particularly restrictive. Examples of the fixing method include a method using an adhesive and a method using a physical fixture.
In the method using an adhesive, the adhesive is applied on the surfaces on both sides (of the honeycomb cell) surrounding the opening 14 of the honeycomb core 12, and the sound absorber 22 and the second surface plate 20 are placed on the adhesive, respectively. Place and fix to honeycomb core 12. Examples of the adhesive include epoxy adhesives (Araldite (registered trademark) (manufactured by Nichiban Co., Ltd.), etc.), cyanoacrylate adhesives (Aron Alpha (registered trademark) (manufactured by Toagosei Co., Ltd.), etc.), and acrylic adhesives. Adhesives and the like can be mentioned.
As a method using a physical fixture, a sound absorbing body 22 or a first surface plate 16, a sound absorbing body 22, and a second surface plate 20 arranged so as to cover and sandwich the opening 14 of the honeycomb core 12 are used. Examples thereof include a method of sandwiching the honeycomb core 12 between a fixing member such as a rod and fixing the fixing member to the honeycomb core 12 using a fixing tool such as a screw or a screw.

[First surface plate]
The first surface plate 16 has a plate shape and has a plurality of through holes 18 penetrating in the thickness direction. The first surface plate 16 functions as a protective layer of the sound absorbing body 22 on the back side of the first surface plate 16 (between the first surface plate 16 and the honeycomb core 12), and the sound absorbing body 22 directly contacts an external object. It is possible to prevent contact with each other and suppress mechanical damage to the sound absorbing body 22. Further, when the sound absorbing body 22 is located only on the back side of the first surface plate 16, the first surface plate 16 having a plurality of through holes 18 covers the sound absorbing body 22, so that the first surface plate 16 is designed. The appearance of the sound absorbing body 22 can be improved. Hereinafter, a case where the sound absorbing body 22 is located only on the back side of the first surface plate 16 will be mainly described.
The through hole 18 of the first surface plate 16 corresponds to the opening 14 of the honeycomb core 12.
Behind the through hole 18 of the first surface plate 16 and the fine through hole 24 of the sound absorbing body 22 (fine through hole plate 26), the honeycomb core 12 and the second surface plate 20 form a back air layer in a closed space. Will be done. The honeycomb core 12 forming the through hole 18 and the back air layer behind the through hole 18 and the second surface plate 20 form an air column resonance structure. That is, a portion of the honeycomb core 12 having one opening 14, a portion of the sound absorbing body 22 having a plurality of fine through holes 24 corresponding to one opening 14, and one penetrating supporting the portion of the sound absorbing body 22. The portion of the first surface plate 16 having the holes 18 and the portion of the second surface plate 20 corresponding to one opening 14 form an air column resonance structure. Here, the through hole 18 of the first surface plate 16 is a large hole that does not interfere with the air column resonance (does not induce Helmholtz resonance). Further, the sound absorbing body 22 does not constitute the air column resonance itself, but is for adding resistance to the air column resonance structure to widen the sound absorbing band.
Here, the plurality of through holes 18 may be arranged in any way in the first surface plate 16, but they may be arranged regularly to a certain extent according to the plurality of openings 14 of the honeycomb core 12. preferable. In addition, one through hole 18 may be provided in the first surface plate 16.

In the present invention, the thickness of the first surface plate 16 is not particularly limited as long as it can protect the sound absorbing body 22. The thickness of the first surface plate 16 is, for example, preferably 0.01 mm to 50 mm, more preferably 0.1 mm to 30 mm, and particularly preferably 1.0 mm to 10 mm.
The planar shape and size (planar size) of the first surface plate 16 are not particularly limited, and may be appropriately determined according to the place where the soundproof structure 10A using the first surface plate 16 is used, the environment, and the like. You just have to choose.

In the present invention, it is preferable that the plurality of through holes 18 of the first surface plate 16 are arranged so as to correspond to the plurality of openings 14 of the honeycomb core 12, respectively. In particular, it is preferable that one through hole 18 of the first surface plate 16 and one opening 14 of the honeycomb core 12 are arranged so as to have a one-to-one correspondence. However, the present invention is not limited to this, and one opening of the honeycomb core 12 does not interfere with the air column resonance (does not induce Helmholtz resonance) composed of the honeycomb core 12 and the second surface plate 20. Two or more through holes 18 may be provided with respect to 14. In the present invention, the plurality of through holes 18 of the first surface plate 16 are preferably arranged regularly, but may be arranged randomly (irregularly).
The shape of the through hole 18 is preferably a planar shape and a circular shape, but is not particularly limited in the present invention. For example, the shape of the through hole 18 is a square (regular square), a rectangle, a diamond, or another square such as a parallel quadrilateral, a regular triangle, an isosceles triangle, or a triangle such as a right angle triangle, a regular pentagon, or a regular hexagon. It may be a polygon including a regular polygon, an elliptical shape, or the like, or an indefinite shape. The diameter of the through hole 18 can be defined in the same manner as the diameter (size) of the opening 14.

The diameter of the through hole 18 of the first surface plate 16 is preferably 1.0 mm or more, more preferably 5 mm or more, and further preferably 10 mm or more. The diameter of the through hole 18 is preferably 100 mm or less, more preferably 50 mm or less, and particularly preferably 25 mm or less.
Here, the reason for limiting the preferable range of the diameter of the through hole 18 to 1.0 mm or more is that when the diameter of the through hole 18 is smaller than 1 mm, the viscous resistance on the side wall of the through hole 18 increases, and the sound absorbing body 22 This is because if it is arranged under the first surface plate 16, the acoustic resistance becomes too large and the sound absorption characteristic deteriorates.
Further, the reason why the preferable range of the diameter of the through hole 18 is limited to 100 mm or less is that if it is larger than 100 mm, the rigidity of the soundproof structure decreases.
The shape and / or diameter of the through hole 18 may be constant in all the through holes 18, but may include frames of different sizes (including cases where the shape is different).
In the present invention, the diameter of the through hole 18 of the first surface plate 16 is larger than the diameter of the fine through hole 24 of the fine through hole plate 26 which is the sound absorbing body 22, and the through hole of the first surface plate 16 penetrates. The opening ratio of the hole 18 is larger than the opening ratio of the fine through hole 24 of the sound absorbing body 22.

The aperture ratio of the through hole 18 of the first surface plate 16 can be defined as the ratio of the area of the through hole 18 to the area of the closed space (back air layer) described above. When the opening 14 of the honeycomb core 12 is not constant, or when the through hole 18 is not constant, the opening ratio of the through hole 18 can be defined as the average opening ratio of the through hole 18. The average aperture ratio of the through holes 18 can be obtained as the total area ratio of the total through holes 18 to the area of the total openings 14 of the honeycomb core 12 (as a ratio of the total area of all the through holes 18) of the honeycomb core 12. The area of the total openings 14 may be obtained by determining the average diameter and the number of all openings 14 within a predetermined range of the honeycomb core 12 and from the product of the average diameter and the number. Further, the total penetration of the first surface plate 16 may be obtained. The area of the holes 18 may be obtained by determining the average diameter and the number of all through holes 18 within a predetermined range of the first surface plate 16 and from the product of the average diameter and the number.
Here, in the present invention, the opening ratio of the through hole 18 is preferably 1.0% or more, more preferably 5% or more, further preferably 10% or more, and 20% or more. Especially preferable. Here, the reason why the opening ratio is preferably 1.0% or more is that when the opening ratio of the through hole 18 of the first surface plate 16 is 1.0% or more, the air weight of the through hole 18 and the honeycomb. This is because Helmholtz resonance formed by an air spring by the core 12 is less likely to occur, air column resonance determined by the length of the air column of the honeycomb core is generated, and sound absorption in a wide band becomes possible. In order to realize sound absorption in a wider band, an aperture ratio of 5% or more is preferable.
From the viewpoint of rigidity, the aperture ratio is preferably 90% or less, more preferably 80% or less, further preferably 70% or less, and particularly preferably 50% or less.

The reason why the opening ratio of the through hole 18 is more preferably 5% or more can be considered as follows.
The aperture ratio (ratio of the area of the through hole to the area of the closed space) dependence of the vertically incident sound absorption coefficient of the Helmholtz resonance structure as shown in FIG. 9 was obtained by calculation, and further, in their sound absorption spectra, with respect to pink noise. We calculated how much the noise level would go down.
The Helmholtz resonance structure 28 shown in FIG. 9 is one cell of the soundproof structure 10A shown in FIG. 6 excluding the sound absorbing body 22, and is one cell of the soundproof structure 10 shown in FIG. Can be done. The Helmholtz resonance structure 28 has a honeycomb core 12 having an opening 14, a first surface plate 16 having a through hole 18, and a second surface plate 20. In FIG. 9, a is the radius of the through hole 18, w is the diameter of the opening 14, h is the thickness of the first surface plate 16, and l is the thickness of the honeycomb core 12.

FIG. 10 shows the calculation result of the vertically incident sound absorption coefficient when the aperture ratio ar (= 4a ² / w ² ) of the Helmholtz resonance structure 28 is changed.
It can be seen that as the aperture ratio ar increases, the frequency of the peak of the vertically incident sound absorption coefficient shifts to the higher frequency side, and the band expands. This is because when the aperture ratio ar is small, the inductance component due to the through hole 18 is large and induces Helmholtz resonance, whereas when the aperture ratio ar is large, this inductance component becomes small and air column resonance is mainly induced. Because it is.
Multiplying the muffling effect in this sound absorption spectrum by the pink noise gives a spectrum of sound pressure level as shown in FIG.

This sound pressure level is integrated from 10 to 10000 Hz, and the aperture ratio ar and the radius a of the through hole 18 are within the practical range (ar = 1%, 5%, 10%, 15%, 20%, 25%, 30%). , 35%, 40%, 45%, a = 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm), the noise level of the first surface plate 16 and the honeycomb core 12. 16 types of graphs showing the noise level with respect to the aperture ratio ar are calculated by shaking the thickness l within a practical range (h = 0.5 mm, 1 mm, 2 mm, 5 mm, l = 10 mm, 20 mm, 30 mm, 40 mm). Obtained.
One of the results is shown in FIG. 12 as a representative.
From the graph shown in FIG. 6, it can be seen that the noise level sharply decreases when the aperture ratio reaches 5%. Further, it can be seen that the noise level further decreases at 10%, although the amount of decrease decreases. Furthermore, it can be seen that when it reaches 20%, the amount of decrease reaches the bottom. The remaining graphs showed similar results.
On the other hand, the upper limit of the aperture ratio is better for the sound deadening effect as the aperture ratio is higher, but if it is too large, the rigidity of the first surface plate is lowered, so 90% or less is preferable, and 70% or less is more preferable. The most preferable is 50% or less, which saturates the muffling effect.

The calculation method is as follows.
Assuming that the acoustic impedance of the Helmholtz resonance structure 28 is Zh, it can be expressed by the following equation (1).
R is the acoustic resistance in the through hole 18, and is set so that the sound absorption coefficient becomes 99% at the time of resonance (imaginary part is 0).
ar is the opening ratio and is represented by the ratio of the area of the through hole 18 to the area of the closed space (ar = 4a ² / w ² ). h'is the thickness of the first surface plate 16 including the end correction of the through hole 18. Further, ρ is the air density, c is the speed of sound, l is the length of the back space, and ω is the angular frequency.
The first term of the imaginary part indicates the inductance of the through hole 18, and the second term indicates the capacitance of the closed space. As the aperture ratio ar increases, the inductance component decreases, and the characteristics of air column resonance, which causes resonance with the capacitance component, become stronger.

Using the acoustic impedance of the Helmholtz resonance structure 28, the vertically incident sound absorption coefficient α was calculated from the following equation (2).
Z _air = ρc, ρ: air density, c: sound velocity Also, set the sound pressure level p of pink noise to p = -10log (f / fo) (set to fo = 1000Hz), and set the above sound pressure level to a linear value. The noise level was calculated by multiplying the above sound absorption effects.

Further, as the material of the first surface plate 16, the sound absorbing body 22 can be protected, and the sound absorbing body 22 is supported between the honeycomb core 12 and the first surface plate 16 so that the sound absorbing body 22 is supported on one surface of the honeycomb core 12. As long as the body 22 can be sandwiched and the distance between the body 22 and the second surface plate 20 can be maintained constant, the same material as the honeycomb core 12 can be used without particular limitation.
As for the material of the first surface plate 16, the first surface plate 16 protects the sound absorbing body 22, and the honeycomb core 12 and the second surface plate 20 are behind the through holes 18 of the first surface plate 16. It suffices if the air column resonance structure can be constructed by.
Further, the first surface plate 16 is preferably made of paper, metal, or resin.

[Second surface plate]
Next, the second surface plate 20 is arranged on the other surface of the honeycomb core 12 (lower surface in FIG. 6; that is, the surface opposite to the side on which the sound absorbing body 22 is provided) at intervals from the first surface plate 16. Will be done.
The second surface plate 20 is for sealing the other side (lower side in FIG. 6) of the plurality of openings 14 of the honeycomb core 12, and is connected to the first surface plate 16 with the sound absorbing body 22 and the sound absorbing body 22. It is for sandwiching the honeycomb core 12.
The thickness of the second surface plate 20 is not particularly limited as long as it can support the sound absorbing body 22 and the honeycomb core 12 with the first surface plate 16, but is preferably 0.1 mm to 100 mm, for example. It is more preferably 1 mm to 50 mm, and particularly preferably 5 mm to 20 mm.
The plane shape and size (plane size) of the second surface plate 20 are not particularly limited, and depend on the plane shape and size of the first surface plate 16, the sound absorbing body 22, and the honeycomb core 12. It may be decided as appropriate, or it may be selected.

Further, the material of the second surface plate 20 is not particularly limited as long as the sound absorbing body 22 and the honeycomb core 12 can be sandwiched between the first surface plate 16 and the same material as the first surface plate 16. be able to. For example, as the material of the second surface plate 20, various metals such as paper, aluminum, and iron, and various resin materials such as polyethylene terephthalate (PET) can be used.
The second surface plate 20 is preferably made of paper, metal, or resin.
Further, if the sound absorbing body 22 and the honeycomb core 12 can be sandwiched between the second surface plate 20 and the first surface plate 16, the second surface plate 20 may be a component member of various devices for installing a soundproof structure, a wall, or the like. Good. That is, for example, when a soundproof structure composed of the first surface plate 16, the sound absorbing body 22, and the honeycomb core 12 is installed on the wall, the surface of the honeycomb core 12 opposite to the surface on which the first surface plate 16 is arranged. May be configured to use the wall as the second surface plate 20 by arranging the wall so as to be in contact with the wall.

In the above-mentioned example, the first surface plate 16, the honeycomb core 12, and the second surface plate 20 are made of different members, but the honeycomb core 12, and the second surface plate 20 may be integrated. .. Alternatively, the sound absorbing body 22, the honeycomb core 12, and the second surface plate 20 may be integrated.
A member or the like in which the honeycomb core 12 and the second surface plate 20 are integrated can be manufactured by, for example, a 3D printer. Further, as for the member in which the sound absorbing body 22, the honeycomb core 12 and the second surface plate 20 are integrated, for example, the member forming the sound absorbing body 22 and the honeycomb core 12 and the second surface plate 20 are integrally molded by a 3D printer. Later, as will be described later, it can be produced by forming a fine through hole 24 in a member forming the sound absorbing body 22 with a laser.

[Sound absorber]
Next, the sound absorbing body 22 is arranged in contact with one surface of the honeycomb core 12 (upper surface in FIG. 6) and the other main surface of the first surface plate 16 (lower surface in FIG. 6). 1 It is sandwiched between the surface plate 16 and the honeycomb core 12. The sound absorbing body 22 functions as an air column resonance structure in a closed space behind a plurality of fine through holes of the sound absorbing body 22 formed by the sound absorbing body 22 itself, the honeycomb core 12, and the second surface plate 20. is there.
The sound absorbing body 22 is preferably a fine through-hole plate or a film having a plurality of fine through holes. Examples of the sound absorbing body 22 include a sound absorbing body made of fibers such as woven fabric, knitting, non-woven fabric, and felt, a porous material such as urethane, and a through-hole plate having through holes.
In the example shown in FIG. 6, the sound absorbing body 22 is arranged between the first surface plate 16 and the honeycomb core 12, and has only one surface (lower surface in FIG. 6) located on the honeycomb core 12 side of the first surface plate 16. However, the present invention is not limited to this, and may be arranged on both surfaces of the first surface plate 16.

In the example shown in FIG. 6, the sound absorbing body 22 is composed of a fine through-hole plate 26 having a plurality of fine through holes 24 penetrating in the thickness direction.
The plurality of fine through holes 24 of the fine through hole plate 26 preferably have an average diameter of 1.0 μm to 250 μm. The fine through hole 24 may be perforated in the fine through hole plate 26 regularly or randomly in shape, size (diameter), and arrangement. The diameter of the fine through hole 24 can be defined in the same manner as the diameter of the through hole 18.
The reason why the average diameter of the fine through holes 24 is preferably 1.0 μm to 250 μm is that if the average diameter is less than 1.0 μm, the acoustic resistance becomes too large and the sound absorption characteristics deteriorate, and the average diameter becomes This is because if it exceeds 250 μm, the inductance due to the fine through hole 24 becomes large and the band becomes narrow.
The sound absorbing body 22 may be a film-like film or a fibrous film as long as it has a plurality of fine through holes 24 penetrating in the thickness direction. In the case of a fibrous film, the space between the fibers can be regarded as a fine through hole 24. Since the fine through-hole plate 26 may have regularity or randomness in the fine through-holes 24, it may be a film of the fiber itself, and may be a woven fabric or a non-woven fabric having various textures. good.
The sound absorbing body 22 made of the fine through-hole plate 26 is more preferable because a high sound absorbing effect can be obtained even in a thin state.

Further, the shape of the fine through hole 24 is preferably a planar shape and a circular shape, but is not particularly limited in the present invention. For example, the shape of the fine through hole 24 may be a rectangle, a diamond, or another quadrangle such as a parallelogram, a regular triangle, an isosceles triangle, or a triangle such as a right triangle, a regular polygon, or a regular polygon such as a regular hexagon. It may be a polygon including, an elliptical shape, or the like, or it may be an indefinite shape.
The soundproof structure 10A is formed by an air column resonance structure formed by a honeycomb core 12 and a second surface plate 20 behind a sound absorbing body 22 composed of a first surface plate 16 having a through hole 18 and a fine through hole plate 26. It has the effect of improving the sound absorption performance and widening the sound absorption frequency.

In the soundproof structure 10A, the average diameter of the plurality of fine through holes 24 formed in the fine through hole plate 26 is 0.1 μm or more and less than 100 μm, and the average aperture ratio of the fine through holes 24 is in the following range. In some cases, the fine through-hole plate 26 alone has high sound absorption independently without the resonance structure formed by the first surface plate 16 having the through holes 18, the honeycomb core 12, and the second surface plate 20. It can function as a soundproof structure that produces an effect.
When the average diameter of the plurality of fine through-holes 24 of the fine through-hole plate 26 is phi (μm) and the thickness of the fine through-hole plate 26 is t (μm), rho is greater than 0 and less than 1. So, with rho_center = (2 + 0.25 × t) × phi ^-1.6 as the center, with rho_center- (0.052 × (phi / 30) ^-2 ) as the lower limit, rho_center + (0.795 × (phi / 30) ^-2 ) It is in the upper limit range.

The fine through hole plate 26 has a fine through hole 24 having an average diameter of 0.1 μm or more and less than 100 μm with an average aperture ratio in the above range, so that the fine through hole 24 is included in the fine through hole 24 when sound passes through the fine through hole 24. Sound is absorbed by friction between the wall surface and air. That is, the fine through-hole plate 26 is a closed space of the back air layer of the resonance structure formed by the first surface plate 16 having the through hole 18, the fine through-hole plate 26 itself, the honeycomb core 12, and the second surface plate 20. It is possible to combine sound absorption by resonance with and sound absorption by a mechanism other than resonance. As described above, the sound absorption in the fine through hole plate 26 is the sound absorption effect due to the air column resonance that causes resonance between the air layer in the fine through hole 24 and the air layer in the closed space to absorb sound, and the sound absorption in the fine through hole 24. The sound absorbing effect is combined with the friction between the inner wall surface of the fine through hole 24 and the air when passing through.

The sound absorbing mechanism of the sound absorbing body 22 itself made of the fine through hole plate 26 is to heat energy of sound energy due to friction between the inner wall surface of the fine through hole 24 and air when sound passes through the fine through hole 24. It was presumed to be a change in. This mechanism is different from the mechanism by resonance because it is caused by the fine size of the fine through hole 24. The path that passes directly as sound in the air through the fine through hole 24 has a much smaller acoustic impedance than the path that is once converted into membrane vibration and then radiated as sound again. Therefore, the sound is easier to pass through the path of the fine through hole 24 than the membrane vibration. When passing through the fine through-hole portion, sound is aggregated and passed from the entire wide area on the fine through-hole plate 26 to the narrow area of the fine through-hole 24. The local velocity becomes extremely large due to the sound gathering in the fine through hole 24. Since the friction correlates with the velocity, the friction increases in the fine through hole 24 and is converted into heat.
When the average diameter of the fine through hole 24 is small, the ratio of the edge length of the fine through hole 24 to the opening area becomes large, so that the friction generated at the edge portion and the inner wall surface of the fine through hole 24 can be increased. Conceivable. By increasing the friction when passing through the fine through hole 24, sound energy can be converted into heat energy and sound can be absorbed.

Further, there is an optimum ratio for the average opening ratio of the fine through holes 24, and particularly when the average diameter is relatively large, such as about 50 μm or more, the smaller the average opening ratio, the higher the absorption rate. When the average aperture ratio is large, sound passes through each of the many fine through holes 24, whereas when the average aperture ratio is small, the number of fine through holes 24 is small, so that one fine The sound passing through the through hole 24 is increased, the local velocity of air when passing through the fine through hole 24 is further increased, and the friction generated at the edge portion and the inner wall surface of the fine through hole 24 can be further increased. ..

As described above, the sound absorption by the fine through hole 24 itself functions as the fine through hole plate 26 alone, so that the size can be freely set. Therefore, when the sound absorbing bodies 22 are arranged on both surfaces of the first surface plate 16, the fine through holes 24 of the fine through hole plates 26 arranged on the upper side in FIG. 6 of the first surface plate 16 are formed. It is valid.
Further, as described above, the sound absorption by the fine through hole 24 is absorbed by the friction when the sound passes through the fine through hole 24, so that the sound can be absorbed regardless of the frequency band of the sound, and the sound is absorbed in a wide band. Can be done.
Further, since it functions by forming the fine through hole 24 in the fine through hole plate 26, the degree of freedom in selecting the material of the fine through hole plate 26 is high, and pollution of the surrounding environment and problems of environmental resistance are also considered in the environment. Since the material can be selected at the same time, problems can be reduced.
Further, since the fine through hole plate 26 has the fine through hole 24, even when a liquid such as water adheres to the fine through hole plate 26, water avoids the portion of the fine through hole 24 due to surface tension. Since the fine through hole 24 is not blocked, the sound absorption performance is unlikely to deteriorate.
Further, since the fine through-hole plate 26 is a thin layered film, it can be curved according to the place where it is arranged.

Here, from the viewpoint of sound absorption performance and the like, the upper limit of the average diameter of the fine through holes 24 is less than 100 μm, preferably 80 μm or less, more preferably 70 μm or less, further preferably 50 μm or less, and most preferably 30 μm or less. This is because as the average diameter of the fine through holes 24 becomes smaller, the ratio of the edge length of the fine through holes 24 that contributes to friction in the fine through holes 24 to the opening area of the fine through holes 24 becomes larger, and the friction becomes larger. Because it is easy to occur.
The lower limit of the average diameter is preferably 0.5 μm or more, more preferably 1.0 μm or more, and even more preferably 2 μm or more. If the average diameter is too small, the viscous resistance when passing through the fine through hole 24 is too high to allow sufficient sound to pass through, so that the sound absorbing effect cannot be sufficiently obtained even if the aperture ratio is increased.

Further, as described above, the average aperture ratio rho of the fine through hole 24 is the average aperture ratio of the fine through hole 24 when the average diameter is phi (μm) and the thickness of the fine through hole plate 26 is t (μm). rho is a range larger than 0 and smaller than 1, with rho_center = (2 + 0.25 × t) × phi ^-1.6 as the center and rho_center- (0.052 × (phi / 30) ^-2 ) as the lower limit, rho_center + ( It falls within the range up to 0.795 × (phi / 30) ^-2 ).
The average aperture ratio rho is preferably in the range of rho_center-0.050 × (phi / 30) ^-2 or more, rho_center + 0.505 × (phi / 30) ^-2 or less, and rho_center-0.048 × (phi / 30) ^-2 or more. , Rho_center + 0.345 × (phi / 30) ^-2 or less is more preferable, rho_center-0.085 × (phi / 20) ^-2 or more, rho_center + 0.35 × (phi / 20) ^-2 or less is more preferable. The range of (rho_center-0.24 × (ph i / 10) ^-2 ) or more and (rho_center + 0.57 × (phi / 10) ^-2 ) or less is particularly preferable, and (rho_center-0.185 × (ph i / 10) ^-2 ) or more, (rho_center + 0.34 × (phi / 10) ^-2 ) The following range is the most preferable.

As described above, in the soundproof structure 10A, when the average diameter of the plurality of fine through holes 24 formed in the fine through hole plate 26 which is the sound absorbing body 22 is 0.1 μm or more and less than 100 μm, the average opening of the fine through holes 24 Setting the ratio rho in the above range is to optimize the sound absorption ratio of the sound absorbing body 22 alone (the absorption ratio when the sound passes through the sound absorbing body 22). In this way, optimizing the sound absorption coefficient of the sound absorbing body 22 alone (the absorption rate when the sound passes through the sound absorbing body 22) obtains a high acoustic resistance in the sound absorbing body 22. Therefore, like the soundproof structure 10A, the fine through-hole plate 26 having the fine through-holes 24 having the average opening ratio rho satisfying the above range is used as the sound absorbing body 22, and the first surface plate 16 having the through holes 18 and the honeycomb core 12 By using it between, the sound absorption of the fine through hole 24 itself and the resonance in the air column resonance structure formed by the first surface plate 16, the sound absorbing body 22, the honeycomb core 12, and the second surface plate 20 cause a wide band. It is possible to add a large acoustic resistance value that is optimal for obtaining characteristics.

The average diameter of the fine through holes 24 is determined by photographing the surface of the sound absorbing body 22 from the surface side of the sound absorbing body 22 at a magnification of 200 times using a high-resolution scanning electron microscope (SEM). , Twenty microthrough holes 24 having an annular shape around them are extracted, their diameters are read, and the average value of these is calculated as the average diameter. If there are less than 20 fine through holes 24 in one SEM photograph, the SEM photograph is taken at another position in the periphery and counted until the total number reaches 20.
The diameter was evaluated using the diameter (diameter equivalent to a circle) when the area of each of the fine through holes 24 was measured and replaced with a circle having the same area. That is, since the shape of the opening of the fine through hole 24 is not limited to a substantially circular shape, when the shape of the opening is a non-circular shape, the diameter of a circle having the same area is evaluated. Therefore, for example, even in the case of a fine through hole having a shape in which two or more fine through holes are integrated, this is regarded as one fine through hole 24, and the diameter corresponding to the circle of the fine through hole 24 is defined as the diameter.
For these operations, for example, "Image J" (https://imagej.nih.gov/ij/) can be used, and the diameter equivalent to a circle, aperture ratio, etc. can all be calculated by Analyze Particles.

The average aperture ratio is a 30 mm × 30 mm field of view (5 locations) of the obtained SEM photograph obtained by photographing the surface of the sound absorbing body 22 from directly above at a magnification of 200 times using a high resolution scanning electron microscope (SEM). Is binarized with image analysis software or the like, the portion of the fine through hole 24 and the non-fine through hole portion are observed, and the ratio is calculated from the total opening area of the fine through hole 24 and the area of the visual field (geometric area). It is calculated from (opening area / geometric area), and the average value in each field of view (5 points) is calculated as the average opening ratio.

Further, the plurality of fine through holes 24 may be composed of fine through holes 24 having one type of diameter as long as the average diameter is 1.0 μm to 250 μm, and the fine through holes 24 having two or more types of diameters. It may consist of. From the viewpoint of productivity, durability, etc., it is preferable that the fine through holes 24 having two or more diameters are formed.
As for productivity, it is better to allow variation in diameter from the viewpoint of performing a large amount of etching treatment. Also, from the viewpoint of durability, the size of dust and dirt differs depending on the environment, so if one type of fine through hole is used, all fine penetration will occur when the size of the main dust almost matches the fine through hole. It will affect the holes. By providing fine through holes with a plurality of types of diameters, the device can be applied in various environments.

Further, by the manufacturing method or the like described in International Publication WO2016 / 060037, it is possible to form a fine through hole having a bulging diameter inside the fine through hole and having a maximum diameter inside. Due to this shape, dust (dust, toner, non-woven fabric, loose foam, etc.) having a size of fine through holes is less likely to be clogged inside, and the durability of the fine through hole plate having fine through holes is improved.
Dust larger than the diameter of the outermost surface of the fine through hole does not enter the fine through hole, while dust smaller than the diameter can pass through the fine through hole as it is because the internal diameter is large.
This is because, considering the opposite shape and the inside is squeezed, the dust that has passed through the outermost surface of the fine through hole is caught in the part with a small diameter inside, and the dust tends to remain as it is. It can be seen that the shape having the maximum diameter is advantageous in suppressing dust clogging.
Further, in a shape such as a so-called tapered shape in which one surface of the film has the maximum diameter and the internal diameter decreases substantially monotonously, "maximum diameter> dust size> the other surface" from the one having the maximum diameter. When dust that satisfies the relationship of "diameter" enters, the internal shape functions like a slope, and the possibility of clogging in the middle is further increased.

Further, from the viewpoint of increasing the friction when the sound passes through the fine through hole, the inner wall surface of the fine through hole is preferably roughened. Specifically, the surface roughness Ra of the inner wall surface of the fine through hole is preferably 0.1 μm or more, more preferably 0.1 μm to 10.0 μm, and 0.2 μm or more and 1.0 μm or less. Is more preferable.
Here, the surface roughness Ra can be measured by measuring the inside of the fine through hole with an AFM (Atomic Force Microscope). As the AFM, for example, SPA300 manufactured by Hitachi High-Tech Science Corporation can be used. The cantilever can be measured in DFM (Dynamic Force Mode) mode using OMCL-AC200TS. Since the surface roughness of the inner wall surface of the fine through hole is about several microns, it is preferable to use AFM because it has a measurement range and accuracy of several microns.

Further, from the SEM image in the fine through hole, each convex portion of the unevenness in the fine through hole can be regarded as a particle, and the average particle size of the convex portion can be calculated.
Specifically, an SEM image (a field of view of about 1 mm x 1 mm) taken at a magnification of 2000 times is captured in Image J, binarized into black and white so that the convex parts are white, and the area of each convex part is analyzed. Obtained by Particles. The equivalent circle diameter assuming a circle having the same area as each area is obtained for each convex portion, and the average value is calculated as the average particle size.
The average particle size of the convex portion is preferably 0.1 μm or more and 10.0 μm or less, and more preferably 0.15 μm or more and 5.0 μm or less.
Here, the ventilation flow resistance of the sound absorbing body 22 (for example, the fine through hole plate 26 having the fine through hole 24) is preferably 10 to 50,000 Rayls, more preferably 50 to 10000 Rayls, and 100 to 2000 Rayls. Is most preferable. This is because the optimum sound absorption coefficient (viscous resistance) can be obtained for the first surface plate 16 having a small diameter of the through hole 18 and a small aperture ratio of 10 Rayls or more, but there is almost no resistance when the diameter is smaller than 10 Rayls. On the other hand, when it exceeds 50,000 Rayls, the resistance is too large and reflection is mainly generated, and the sound absorption effect is reduced.

Further, the thickness of the fine through-hole plate 26 which is the sound absorbing body 22 is not limited, but the thicker the thickness, the larger the frictional energy received when the sound passes through the fine through hole 24, so that the sound absorbing performance is further improved. Conceivable. If it is extremely thin, it is difficult to handle and it is easy to tear, so it is desirable that it is thick enough to hold it. On the other hand, it is preferable that the thickness is thin in terms of miniaturization, air permeability, and light transmission. Further, when etching or the like is used as a method for forming the fine through hole 24, the thicker the thickness, the longer it takes to produce the fine through hole 24. Therefore, from the viewpoint of productivity, the thinner one is desirable.
As the thickness of the sound absorbing body 22 becomes thicker, the rigidity of the first surface plate 16 having the honeycomb core 12 and the through hole 18 becomes lower, so that the sound absorbing body 22 is preferably thinner. Therefore, the thickness of the sound absorbing body 22 is preferably 50 mm or less, more preferably 20 mm or less, and even more preferably 10 mm or less. On the other hand, if the thickness of the sound absorbing body 22 becomes too thin, the sound absorbing body 22 is easily damaged mechanically. Therefore, the sound absorbing body 22 is preferably 0.1 μm or more, more preferably 1.0 μm or more, and 10 μm or more. Is more preferable.
When the sound absorbing body 22 is thick (for example, when it is 1.0 mm or more), the distance between the first surface plate 16 and the second surface plate 20 becomes longer by the thickness of the sound absorbing body 22, so that the sound absorbing body 22 has a wide band at a low frequency. Can absorb sound.
The planar shape and size (planar size) of the sound absorbing body 22 are not particularly limited, and may be appropriately determined according to the planar shape and size of the first surface plate 16, and may be appropriately selected. ..

Hereinafter, a case where the sound absorbing body 22 is a film-shaped (film-shaped) fine through-hole plate 26 having a plurality of fine through holes 24 will be described.
The material of such a fine through-hole plate 26 is not particularly limited, and a material similar to that of the honeycomb core 12 can be used. Examples of the material of the sound absorbing body 22 include aluminum, titanium, nickel, permalloy, 42 alloy, coval, nichrome, copper, beryllium, phosphorus bronze, brass, white, tin, zinc, iron, tantalum, niobium, molybdenum, and zirconium. , Gold, silver, platinum, palladium, steel, tungsten, lead, stainless steel, and various metals such as iridium; alloy materials made of these metals; PET (polyethylene terephthalate), TAC (triacetyl cellulose), polyvinyl chloride, polyethylene, Polyvinyl chloride, polymethylbenzene, COP (cycloolefin polymer), polycarbonate, zeonoa, PEN (polyethylene naphthalate), polypropylene, and polyimide, ABS resin (Acrylonitrile, Butadiene), styrene (Styrene) Polymerized synthetic resin), resin materials such as PLA resin, and the like can be used. Further, glass materials such as thin film glass; fiber-reinforced plastic materials such as CFRP (Carbon Fiber Reinforced Plastics) and GFRP (Glass Fiber Reinforced Plastics) can also be used.

The material of the sound absorbing body 22 is preferably a flame-retardant material, particularly when the first surface plate 16, the second surface plate 20, and the honeycomb core 12 are made of a flammable material such as paper. The flame-retardant material is more preferably a metal material.
That is, from the viewpoints of high flame retardancy, high Young's modulus, low vibration even if the thickness is thin, and easy to obtain the effect of sound absorption due to friction in the fine through holes, it is more preferable to use a metal material. preferable. Of these, copper, nickel, stainless steel, titanium and aluminum are more preferable from the viewpoint of cost and availability. In particular, it is most preferable to use aluminum or an aluminum alloy from the viewpoints of light weight, easy formation of minute through holes by etching, etc., availability, cost, and the like.
When a metal material is used, the surface may be metal-plated from the viewpoint of suppressing rust.
Further, the average diameter of the fine through holes may be adjusted to a smaller range by applying metal plating to at least the inner surface of the fine through holes.

Further, by using a material having conductivity and not being charged like a metal material as the material of the sound absorbing body 22, minute dust and dirt are not attracted to the film by static electricity, and the fine through-hole plate 26 is made fine. It is possible to prevent the through hole 24 from being clogged with dust, dust, etc. and deteriorating the sound absorbing performance.
Further, by using a metal material as the material of the fine through-hole plate, the heat resistance can be increased. In addition, ozone resistance can be increased.
Further, when a metal material is used as the material of the fine through-hole plate, radio waves can be shielded.

Further, since the metal material has a high reflectance to radiant heat due to far infrared rays, by using a metal material (conductive material) as a material for the fine through-hole plate, it also functions as a heat insulating material for preventing heat transfer due to radiant heat. At that time, a plurality of fine through holes are formed in the fine through hole plate, but since the diameter of the fine through holes is small, the fine through hole plate functions as a reflective film.
It is known that a structure in which a plurality of fine through holes are formed in a metal functions as a frequency high-pass filter. For example, a window with a metal mesh of a microwave oven has a property of transmitting visible light having a high frequency and shielding the microwave used in the microwave oven. In this case, when the diameter of the fine through hole is Φ and the wavelength of the electromagnetic wave is λ, the long wavelength component having a relationship of Φ <λ does not pass through, and the short wavelength component having Φ> λ functions as a penetrating filter.
Now consider the response to radiant heat. Radiant heat is a heat transfer mechanism in which far-infrared rays are emitted from an object according to the temperature of the object and transmitted to other objects. According to Wien's radiation law, radiant heat in an environment of about room temperature is distributed around λ = 10 μm, and effectively radiates heat up to about three times that wavelength (up to 30 μm) on the long wavelength side. It is known to contribute to communicating in. Considering the relationship between the diameter Φ and the wavelength λ of the high-pass filter, when Φ = 20 μm, the component of λ> 20 μm is strongly shielded, while when Φ = 50 μm, the relationship is Φ> λ and the radiant heat is a fine through hole. It propagates through. That is, since the diameter Φ is several tens of μm, the propagation performance of radiant heat changes greatly depending on the difference in diameter Φ, and it can be seen that the smaller the diameter Φ, that is, the smaller the average diameter, the more it functions as a radiant heat cut filter. Therefore, from the viewpoint of a heat insulating material that prevents heat transfer due to radiant heat, the average diameter of the fine through holes formed in the fine through hole plate is preferably 20 μm or less.

On the other hand, when transparency is required for the entire soundproof structure, a resin material or glass material that can be made transparent can be used. For example, the PET film has a relatively high young ratio among resin materials, is easily available, and has high transparency, so that a fine through hole can be formed to form a suitable soundproof structure.
In addition, the durability of the fine through-hole plate is improved by appropriately performing surface treatment (plating treatment, oxide film treatment, surface coating (fluorine, ceramic), etc.) according to the material of the fine through-hole plate. be able to. For example, when aluminum is used as the material for the fine through-hole plate, an oxide film can be formed on the surface by performing anodizing treatment (anodizing treatment) or boehmite treatment. By forming an oxide film on the surface, corrosion resistance, wear resistance, scratch resistance and the like can be improved. Further, by adjusting the processing time and adjusting the thickness of the oxide film, it is possible to adjust the color tone by optical interference.

In addition, the fine through-hole plate can be colored, decorated, decorated, designed, and the like. As a method for applying these, an appropriate method may be selected depending on the material of the fine through-hole plate and the state of surface treatment. For example, printing using an inkjet method can be used. Further, when aluminum is used as the material of the fine through-hole plate, highly durable coloring can be performed by performing color alumite treatment. The color alumite treatment is a treatment in which the surface is anodized, then the dye is permeated, and then the surface is sealed. As a result, it is possible to obtain a fine through-hole plate having a high design such as the presence or absence of metallic luster and color. In addition, by performing alumite treatment after forming the fine through holes, an anodized film is formed only on the aluminum part, so that the dye does not cover the fine through holes and the sound absorption characteristics are not reduced. It can be performed.
By combining with the above alumite treatment, various colors and designs can be added.

Next, a case where the fine through-hole plate is a fibrous film will be described.
As described above, the fine through-hole plate may be the fiber itself or a fibrous film such as a non-woven fabric. In the case of a fibrous film, the space between the fibers can be regarded as a through hole.
Further, when the fibers themselves are made into a film, the fibers are irregularly overlapped, and in the case of a non-woven fabric, the fibers are woven irregularly. Therefore, the fibers are not parallel or orthogonal to each other, but the fibers are not. A through hole is formed in the space surrounded by. Therefore, the average diameter and the average aperture ratio of the fine through holes are determined by the fiber diameter and the density.
When the fine through-hole plate is a fibrous film, the thickness is preferably 250 μm or less, more preferably 100 μm or less.
The fiber diameter of the fibrous film is usually about several tens of μm. Therefore, by setting the thickness to 100 μm or less, many threads are not laminated. Therefore, the space surrounded by the fibers can be regarded as a through hole. As a result, even a fibrous member can handle the sound absorbing characteristic in the same manner as a plate-shaped member having a through hole.

As the material of the fibrous film, 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, ethylene vinyl acetate resin fiber Fibers made of resin materials such as synthetic rubber fibers, copolymerized polyamide resin fibers, copolymerized polyester resin fibers; paper (tissue paper, Japanese paper, etc.); SUS fibers (Stainless fiber sheet "Tommy Filec" manufactured by Tomoegawa Paper Co., Ltd. Fibers made of metal materials such as "SS"); fibers made of carbon materials, fibers made of carbon-containing materials, etc. can be mentioned.
Since the absorption characteristics in the present invention are generated by the passage of sound through the fine through holes, there is almost no change in the acoustic characteristics even if the material of the fibrous member changes. Therefore, the material can be freely selected. It can also be selected according to characteristics other than acoustic characteristics. For example, a metal material can be selected when heat resistance is required, and a plastic material can be selected when weight reduction is required.

Further, the sound absorbing body 22 and the first surface plate 16 may be arranged in contact with each other, but are preferably bonded and fixed.
By adhering and fixing the sound absorbing body 22 and the first surface plate 16, the rigidity of the sound absorbing body 22 can be made higher, and the resonance vibration frequency can be made higher.
The adhesive used when the sound absorbing body 22 and the first surface plate 16 are adhesively fixed may be selected according to the material of the sound absorbing body 22 and the material of the first surface plate 16. Examples of the adhesive include epoxy-based adhesives (Araldite (registered trademark) (manufactured by Nichiban Co., Ltd.), etc.), cyanoacrylate-based adhesives (Aron Alpha (registered trademark) (manufactured by Toa Synthetic Co., Ltd.), etc.), and acrylic. Examples include system adhesives.

Further, the sound absorbing body 22 preferably has a deodorizing function.
When imparting a deodorizing function to the sound absorbing body 22, if the sound absorbing body 22 is a fibrous film, a fine through-hole plate, or a porous material, the fibers may be impregnated with a deodorant. ..
As the deodorant, a known deodorant can be used. Examples of deodorants include Kobayashi Pharmaceutical Co., Ltd.'s unscented space air and cloth deodorant mist, Orbs's Rivage Natural Eucalyptus Brush Up Spray (CR-TN012), and Goodwill's Biowill Clear Spray (Crystal-TN012). E483184H) and the like can be mentioned.

Next, the soundproof structure 10 shown in FIGS. 4 and 5 includes a honeycomb core 12 having a plurality of openings 14, a plate-shaped first surface plate 16 having a plurality of through holes 18, and a second surface plate 20. Have. That is, the soundproof structure 10 shown in FIGS. 4 and 5 is obtained by removing the sound absorbing body 22 between the first surface plate 16 and the honeycomb core 12 from the soundproof structure 10A shown in FIGS. 6 and 7. Therefore, in the following, only the differences from the soundproof structure 10A will be described.
Here, the first surface plate 16 and the second surface plate 20 are arranged so as to sandwich the honeycomb core 12 at intervals from each other. The first surface plate 16 is directly bonded to one surface of the honeycomb core 12. The second surface plate 20 is joined to the other surface of the honeycomb core 12.
In addition, in FIG. 5, in order to make it easy to understand the structure of the soundproof structure 10, the portion where the first surface plate 16 is broken is shown on the left side of FIG.

The thickness of the honeycomb core 12 is equal to the distance (separation distance) between the first surface plate 16 and the second surface plate 20.
Further, as a material of the honeycomb core 12 in the soundproof structure 10, the honeycomb core 12 is lightweight and has high rigidity, the honeycomb core 12 can support the first surface plate 16, and the first surface plate 16 and the second surface plate 20 If the interval between them can be maintained constant, and a Helmholtz resonance structure or an air column resonance structure can be formed together with the first surface plate 16 and the second surface plate 20 according to the diameter of the through hole 18 of the first surface plate 16. Not particularly restrictive.
Further, the thickness of the material of the honeycomb core 12 is such that the honeycomb core 12 is lightweight and has high rigidity, and has rigidity capable of supporting the first surface plate 16, and the first surface plate 16 and the second surface plate 20 The distance between the honeycomb cores 12 can be kept constant, and the honeycomb core 12 together with the first surface plate 16 and the second surface plate 20 has a Helmholtz resonance structure or an air column depending on the diameter of the through hole 18 of the first surface plate 16. As long as the resonance structure can be constructed, it is not particularly limited.

It is preferable that the first surface plate 16 and the honeycomb core 12 are fixed without gaps, similarly to the honeycomb core 12 and the second surface plate 20. The fixing method between the first surface plate 16 and the honeycomb core 12 may be the same fixing method as the fixing method between the honeycomb core 12 and the second surface plate 20. In the method using an adhesive, the adhesive is applied on the surfaces on both sides (of the honeycomb cell) surrounding the opening 14 of the honeycomb core 12, and the first surface plate 16 and the second surface plate 20 are placed on the adhesive. It is placed and fixed to the honeycomb core 12.
The through hole 18 of the first surface plate 16 corresponds to the opening 14 of the honeycomb core 12.
Behind the through hole 18 of the first surface plate 16, a back air layer in a closed space is formed by the first surface plate 16, the honeycomb core 12, and the second surface plate 20. The first surface plate 16, the honeycomb core 12, and the second surface plate 20 forming the through hole 18 and the back air layer behind the through hole 18 form a Helmholtz resonance structure or an air column resonance structure. That is, a portion of the honeycomb core 12 having one opening 14, a portion of the first surface plate 16 having one through hole 18 corresponding to one opening 14, and a second surface plate 20 corresponding to one opening 14. The part constitutes a Helmholtz resonance structure or an air column resonance structure.

Next, the soundproof structure 10B shown in FIG. 8 includes a honeycomb core 12 having a plurality of openings 14, a plate-shaped first surface plate 16 having a plurality of through holes 18, a second surface plate 20, and a sound absorbing body 22. Urethane 27 and the like. That is, in the soundproof structure 10A shown in FIG. 8, in the soundproof structure 10 shown in FIGS. 4 and 5, urethane 27 is provided as the sound absorbing body 22 on the surface of the first surface plate 16 (the surface opposite to the honeycomb core 12). It has. Therefore, in the following, only the differences from the soundproof structure 10 will be described.
Since the soundproof structure 10B shown in FIG. 8 has urethane 27 as the sound absorbing body 22 on the surface of the first surface plate 16 (the surface opposite to the honeycomb core 12), for example, the soundproofing in the high frequency band is improved. It is possible to widen the frequency band of soundproofing.

Examples of such a sound absorbing body 22 include non-woven fabric, woven cloth, knitting, gypsum board, felt, and the like, in addition to urethane 27.
Further, the method of fixing the urethane 27 to the surface of the first surface plate 16 is the same as the fixing method of the first surface plate 16 and the honeycomb core 12 and the fixing method of the honeycomb core 12 and the second surface plate 20. Any method will do.
In the soundproof structure 10B shown in FIG. 8, it goes without saying that the fine through-hole plate 26 shown in FIGS. 6 and 7 may be used as the sound absorbing body 22 instead of the urethane 27. When the fine through-hole plate 26 is used, the same effect as that of the soundproof structure 10A shown in FIGS. 6 and 7 can be obtained.

Next, in the soundproof box 30 shown in FIGS. 1 and 2, the soundproof structure 11 constituting the soundproof wall 36 will be described.
As shown in FIG. 13, it has a honeycomb core 12 having a plurality of openings 14 and two second surface plates 20 sandwiching the honeycomb core.
The soundproof structure 11 is also low in soundproofing performance, but is thin, lightweight, and has high rigidity. Therefore, the soundproof wall 36 is thin, sturdy, and lightweight.
Therefore, the soundproof box 30 composed of soundproof walls 32, 34, and 36 made of soundproof structures 10, 10A, and 11, which are thin, lightweight, and have high rigidity, is thin, sturdy, and lightweight.
In order to impart soundproofing performance to the soundproofing structure 11, as the sound absorbing body 22 on the surface of one of the second surface plates 20 (the surface opposite to the honeycomb core 12) as in the soundproofing structure 11A shown in FIG. Urethane 27 or the like may be installed. Also in the soundproof structure 11A, by having urethane 27 or the like on the surface of the second surface plate 20, soundproof performance can be imparted and improved as in the soundproof structure 10B shown in FIG.
As described above, when the soundproof structure in which the sound absorbing body 22 (urethane 27) is arranged on the second surface plate 20 having no through hole like the soundproof structure 11A shown in FIG. 14 is used as the soundproof wall, up to a low frequency. In order to absorb sound, it is necessary to make the sound absorbing body 22 thicker, and the volume inside the soundproof box is reduced. Therefore, as shown in FIGS. 4 and 5, the first surface plate 16 having the through hole 18 is provided. It is preferable to use the soundproof structure to be used as a soundproof wall.

In addition to the above, the soundproof structure used in the present invention can also be used as a soundproof member in which two or more types of soundproof walls having soundproof structures having different frequency characteristics as described below are combined.
For example, as a soundproofing member having the soundproofing structure of the present invention,
Soundproofing material for building materials: Soundproofing material used for building materials,
Soundproofing material for air conditioning equipment: Soundproofing material installed in ventilation openings and air conditioning ducts to prevent external noise.
Soundproofing member for external opening: Soundproofing member installed on the window of the room to prevent noise from indoors or outdoors.
Ceiling soundproofing member: A soundproofing member installed on the ceiling of a room to control the sound in the room.
Soundproofing member for floor: Soundproofing member installed on the floor to control the sound in the room,
Soundproofing member for internal opening: Soundproofing member installed on the door or bran part of the room to prevent noise from each room.
Toilet soundproofing material: Installed inside the toilet or at the door (indoor / outdoor) to prevent noise from the toilet,
Soundproofing material for balconies: Soundproofing material installed on the balcony to prevent noise from your own balcony or the adjacent balcony,
Room sound control member: Soundproof member for controlling the sound of the room,
Simple soundproof room member: Soundproof member that can be easily assembled and moved easily.
Soundproof room material for pets: Soundproof material that surrounds the pet's room and prevents noise,
Amusement facilities: Soundproofing materials installed in game centers, sports centers, concert halls, movie theaters, etc.
Soundproofing material for temporary enclosures for construction sites: Soundproofing members that cover the construction site and prevent noise from leaking around
Soundproofing member for tunnel: A soundproofing member installed in the tunnel to prevent noise leaking inside and outside the tunnel can be mentioned.
The soundproof structure of the first embodiment of the present invention is basically configured as described above.

As shown in FIGS. 1 and 2, the soundproof box 30 of the present invention has a soundproof structure 10 having different frequency characteristics and two types of soundproof walls 32 and 34 having 10A arranged facing each other. It is constructed in a rectangular shape by adding four soundproof walls 36 having 11. Therefore, the soundproof box 30 of the present invention is thin and lightweight, and can obtain high rigidity and high soundproof performance in a wide frequency band.
As described above, in the soundproof box 30, when the soundproof structures 10 having different frequency characteristics and the two types of soundproof walls 32 and 34 having 10A are arranged to face each other, the soundproof performance is high in a wide frequency band. In order to obtain the above, it is preferable to arrange the speakers so as to exhibit the sound absorbing characteristics as shown in FIG.

As shown in FIG. 15, regarding the frequency characteristics of the pair of soundproof walls, in the pair of soundproof walls having sound absorption peaks at different frequencies, the sound absorption coefficient of the soundproof walls having a low frequency absorption peak (f1) is 10%. Of the frequencies, the high frequency side frequency (f2) is equal to or lower than the high frequency absorption peak frequency (f3), and the sound absorption coefficient of the soundproof wall having this absorption peak is 10%, and the low frequency side frequency (f4). ) Or more is preferable. Moreover, this frequency (f4) is preferably equal to or higher than the absorption peak (f1) of a low frequency.
That is, it is preferable to satisfy the following formula (3).
f1 ≦ f4 ≦ f2 ≦ f3 …… (3)
The sound absorption coefficient of the soundproof wall having a low frequency absorption peak (f1) for determining the frequency (f2) is more preferably 25%, and most preferably 50%. Further, the sound absorption coefficient of the soundproof wall having a high frequency absorption peak frequency (f3) for determining the frequency (f4) is more preferably 25%, and most preferably 50%.

In order to form the soundproof box 30 shown in FIGS. 1 and 2, as shown in FIG. 2, first, the soundproof structure 10 of the two soundproof walls 32 and 34 and the second surface plate 20 of 10A are on the front side (outside). Therefore, the first surface plate 16 is joined so as to be on the back side (inside). That is, both ends of the soundproof structure 10 of the two soundproof walls 32 and 34 and the first surface plate 16 of 10A are the side surfaces of the soundproof structure 11 of the two soundproof walls 36 (the second surface plate 20, the honeycomb core 12, and the second). 2 Each side end of the surface plate 20) is adhered and fixed to form four walls on the side surface of the rectangular body. Next, the four ends of the second surface plate 20 of the soundproof structure 11 of the remaining two soundproof walls 36 are the four soundproof walls 32, 34, 36, which form the four surfaces of the rectangular body shown in FIG. And 36, by adhering and fixing to the side surfaces of the soundproof structures 10, 10A, 11, and 11, for example, the ceiling and the bottom surface are formed to form the soundproof box 30 which constitutes the six soundproof walls of the rectangular body. Can be done.
The soundproof structures 10, 10A, and 11 are preferably fixed by using an adhesive in the same manner as the fixing of the honeycomb core 12 and the second surface plate 20, but by a method using a physical fixture. It may be present, and any fixing method may be used.
As described above, by arranging the soundproof box 30 composed of the six walls of the rectangular parallelepiped so as to cover the noise source, a high soundproofing effect in a wide band can be obtained.

The above-mentioned soundproof box 30 uses a soundproof wall including two or more types of soundproof walls having soundproof structures having different frequency characteristics for the six-sided wall of the rectangular body, but the present invention is limited to this. Instead, the soundproof wall may be used for the five walls of the rectangular body to cover the noise source, or the soundproof wall may be used for the four walls of the rectangular body to surround the noise source. Further, in the soundproof box of the present invention, one or more openings (not shown) may be provided in the soundproof structure 10A as an entrance / exit on one wall surface. Further, also in this case, a configuration having openings (not shown) for intake and exhaust may be provided in addition to the entrance and exit.
Further, when the sound absorbing bodies 22 of the soundproofing structures 10A, 10B, and 11A are made of those having a deodorizing effect, the soundproofing box 30 can be used for a pet hut or the like, which is preferable. Further, it is preferable to attach a handle (not shown) to the soundproof box 30 so that the lightweight soundproof box can be carried. That is, it is preferable because the handle functions as a portable soundproof box, for example, a pet gauge.
The above-mentioned soundproof box 30 has a rectangular parallelepiped shape, but the present invention is not limited to this, and as long as it has the shape of a box, it may have a cubic shape or another hexahedral shape. However, in addition to this, a polyhedral shape such as a tetrahedral shape, a pentahedral shape, or an octahedral shape may be used.
The soundproof box of the present invention is basically configured as described above.

The present invention will be described in more detail below based on examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as limiting by the examples shown below.

(Example 1)
Examples of the soundproof structure of the soundproof wall used for the soundproof box used in this embodiment are shown in FIGS. 13, 14, 4, and 6.
Structural example 1 is a soundproof structure 11 in which a paper honeycomb core 12 (manufactured by Corepack Nishikawa) having a thickness of 30 mm is bonded and fixed with a second surface plate 20 (manufactured by Corepack Nishikawa) made of paper having a thickness of 1.0 mm. Yes, as shown in FIG.
Structure Example 2 is a soundproof structure 11A in which urethane having a thickness of 15 mm is adhered and arranged on the second surface plate 20 of the soundproof structure 11 of the structure example 1, and is shown in FIG.

In the structure example 3, a through hole 18 having a diameter of 1.0 mm is formed in the second surface plate 20 on one side of the soundproof structure 11 of the structure example 1 by a laser processing machine (GCC LaserPro C1802) in a staggered manner with a center spacing of 12 mm. It is a soundproof structure 10 having a first surface plate 16, and is shown in FIG. The soundproof structure 10 has a Helmholtz resonance structure in which mass-spring resonance occurs due to the closed space of the through hole 18 and the honeycomb portion on the back surface (a space surrounded by one cell of the honeycomb core 12 and the second surface plate 20). ..
In the structural example 4, a fine through hole 24 having a diameter of 25 μm as a sound absorbing body 22 is provided between the honeycomb core 12 and the first surface plate 16 made of paper in which a through hole 18 having a diameter of 2 mm is formed in parallel with a center spacing of 4 mm. Is a soundproof structure 10A in which a fine through-hole plate 26 made of aluminum having a thickness of 20 μm and opened with an aperture ratio of 6.5% is arranged, and is shown in FIG. The adhesive used for adhesive fixing was spray glue 77 (manufactured by 3M).

FIG. 16 shows the results of measuring the vertical incident sound absorption coefficient of each of Structural Examples 1 to 4 with an acoustic tube by measurement using a self-made acoustic tube.
The measurement of the acoustic characteristics using the self-made acoustic tube was a measurement by the transfer function method using four microphones on the self-made acrylic acoustic tube. This method follows "ASTM E2611-09: Standard Test Method for Measurement of Normal Incidence Sound Transmission of Acoustical Materials Based on the Transfer Matrix Method". As the acoustic tube, for example, a tube having the same measurement principle as WinZac manufactured by Nitto Boseki Acoustic Engineering Co., Ltd. was used. In this way, the acoustic transmission loss can be measured in a wide spectral band. The soundproof structure 10 of the present embodiment was placed at the measurement site of the acoustic tube, and the vertical incident sound absorption coefficient of each soundproof structure was measured in the range of 100 Hz to 4000 Hz. The inner diameter of the acoustic tube is 40 mm, and it can be sufficiently measured up to 4000 Hz or higher.
In the form of Structural Example 1, the vertical incident sound absorption coefficient is low in the measurement range because there is no sound absorber. In Structural Example 2, it can be seen that the sound absorption coefficient increases in the high frequency region. Structural example 3 shows a low-frequency sound absorption characteristic having a peak near 700 Hz. This sound absorption characteristic is due to Helmholtz resonance. It can be seen that Structural Example 4 exhibits high sound absorption characteristics in a band wider than 500 Hz. It is considered that this is caused by the high acoustic resistance of the fine through hole 24 added to the air column resonance of the cell column of the honeycomb core 12.

Five soundproof walls having a soundproof structure of 50 cm × 50 cm were fixed with an adhesive to prepare soundproof boxes of Example 1 and Comparative Examples 1 to 3 to be measured.
A soundproof box in which the soundproof wall 36 made of the soundproof structure 11 of the structure example 1 shown in FIG. 13 was used for the five walls was used as Comparative Example 1.
Comparative Example 2 was obtained by forming one side surface of the soundproof box of Comparative Example 1 into a soundproof wall 32 having the soundproof structure 10 of the structure Example 3 shown in FIG.
Comparative Example 3 was obtained by forming one side surface of the soundproof box of Comparative Example 1 into a soundproof wall 34 having a soundproof structure 10A of Structure Example 4 shown in FIG.
The two sides of the soundproof box of Comparative Example 1 are made into a soundproof wall 32 made of the soundproof structure 10 of the structure example 3 shown in FIG. 4 and a soundproof wall 34 made of the soundproof structure 10A of the structure example 4 shown in FIG. It was set as Example 1.

FIG. 17 shows a measurement system for evaluating the soundproofness of the soundproof boxes of Examples 1 and Comparative Examples 1 to 3 using the soundproof walls of Structural Examples 1 to 4.
As the soundproof box 42 to be measured, a speaker 44 for emitting a sound source was arranged inside the soundproof boxes of Examples 1 and Comparative Examples 1 to 3, respectively. Three microphones 46 were placed inside the soundproof wall of the soundproof box 42, and microphones 48 were placed outside the soundproof box 42 at a position 50 cm from the soundproof box 42 and a height of 70 m, and the sound inside and outside the box from the speaker 44 was measured.
FIG. 18 shows the average noise level (microphone sound pressure level) of the microphone outside the soundproof box 42 when pink noise is emitted from the speaker 44.

In Comparative Example 1, since there is no sound absorbing structure, the volume leaking to the outside is large. In Comparative Example 2, the Helmholtz resonance sound absorption effect of Structural Example 3 has a large soundproofing effect in the vicinity of 630 Hz. On the other hand, in Comparative Example 3, since the wideband sound absorbing structure of Structure Example 4 is used, soundproofing can be performed at a wide frequency. In the first embodiment, the soundproofing effect near 630 Hz by Helmholtz of the structural example 3 and the soundproofing effect of a wide band of the structural example 4 are combined, and a high soundproofing effect can be realized in a wide band.
FIG. 19 shows data (microphone sound pressure level) obtained by averaging the sound pressures of the three microphones inside the box. From this data, it can be seen that the structure of the first embodiment can mute the sound in a wide band even inside the soundproof box.
From the above results, the effect of the present invention is clear.

Although various embodiments and examples of the soundproof structure, the soundproof surrounding structure, and the soundproof box according to the present invention have been described in detail above, the present invention is not limited to these embodiments and examples. Of course, various improvements or changes may be made without departing from the gist of the present invention.

The soundproof box according to the present invention can also be used as, for example, a soundproof hut for pets such as a kennel, a soundproof box for a device (generator, PC) cover that becomes a noise source, or a soundproof room for humans. ..
Further, the soundproof box of the present invention has a box-shaped interior (side walls, ceiling, floor, etc. excluding windows) inside a building or other building structure (for example, a house, a hall, an elevator, a music classroom, a conference room, etc.). It can be used for construction applications such as covering panel materials, transportation applications such as automobile interiors, and distribution applications such as box materials and packing materials.

10, 10A, 10B, 11, 11A Soundproof structure 12 Honeycomb core 14 Opening 16 First surface plate 18 Through hole 20 Second surface plate 22 Sound absorber 24 Fine through hole 26 Fine through hole plate 27 Sound absorbing urethane 28 Helmholtz resonance structure 30, 30A, 42 Soundproof box 32, 32a, 32b, 34, 34a, 34b, 36 Soundproof wall 40 Measurement system 44 Speaker 46, 48 Microphone

Claims (12)

Honeycomb core and
The first surface plate and the second surface plate that sandwich the honeycomb core,
It has a plurality of soundproof walls having a soundproof structure having a through hole formed in the first surface plate.
The plurality of soundproof walls are soundproof boxes having two or more types of soundproof walls having soundproof structures having different frequency characteristics. The soundproof box according to claim 1, wherein the two types of soundproof walls among the two or more types of soundproof walls are arranged so as to face each other. The soundproof box according to claim 2, wherein the further two types of soundproof walls among the two or more types of soundproof walls are arranged facing each other. The soundproof box according to any one of claims 1 to 3, wherein the soundproof structure has a sound absorbing body arranged on a part or the entire surface of at least one surface of the first surface plate. The soundproof box according to claim 4, wherein the soundproof wall having the sound absorbing body and the soundproof wall having the soundproof structure excluding the sound absorbing body are arranged to face each other. The soundproof box according to any one of claims 1 to 5, wherein the first surface plate having the soundproof structure has the through holes having different diameters. The soundproof structure is a Helmholtz resonator by a through hole having at least one diameter of the through holes having different diameters of the first surface plate, one space surrounded by the inner surface of the honeycomb core, and the second surface plate. The soundproof box according to claim 6, which constitutes the above. In the soundproof structure, air column resonance is performed by a through hole having at least one diameter of the through holes having different diameters of the first surface plate, one space surrounded by the inner surface of the honeycomb core, and the second surface plate. The soundproof box according to claim 6, which constitutes a vessel. The soundproof box according to any one of claims 1 to 8, wherein the honeycomb core is made of paper, metal, or resin. The soundproof box according to any one of claims 1 to 9, wherein the second surface plate is made of paper, metal, or resin. The soundproof box according to any one of claims 1 to 10, wherein the first surface plate is made of paper, metal, or resin. When two types of soundproof walls out of the two or more types of soundproof walls are arranged facing each other and are paired with each other, they have sound absorption peaks at different frequencies with respect to the frequency characteristics of the paired soundproof walls. In the pair of soundproof walls, the frequency (f2) on the high frequency side is equal to or less than the high frequency absorption peak frequency (f3) among the frequencies at which the sound absorption coefficient of the soundproof wall having a low frequency absorption peak (f1) is 10%. The soundproof box according to any one of claims 1 to 11, wherein the sound absorption coefficient of the soundproof wall having the absorption peak is equal to or higher than the frequency (f4) on the low frequency side among the frequencies at 10%.