WO2016136973A1

WO2016136973A1 - Sound insulation structure and method for manufacturing sound insulation structure

Info

Publication number: WO2016136973A1
Application number: PCT/JP2016/055904
Authority: WO
Inventors: 真也白田; 昇吾山添; 達矢吉弘; 暁彦大津; 笠松　直史; 納谷　昌之
Original assignee: 富士フイルム株式会社
Priority date: 2015-02-27
Filing date: 2016-02-26
Publication date: 2016-09-01

Abstract

A sound insulation structure having one or more sound insulation cells, wherein: each of the one or more sound insulation cells is provided with a frame having through holes, a film affixed to the frame, and an opening part formed from one or more holes penetrating the film; both end parts of the through holes in the frame are not closed; and the sound insulation structure has, on the low-frequency side of a first natural resonance frequency for the film of the one or more sound insulation cells, a masking peak frequency that is determined due to the opening parts of the one or more sound insulation cells and for which transmission loss is maximum, and selectively insulates sound of a fixed frequency band centered on the peak masking frequency. Thus, it is possible to provide a sound insulating structure that is lightweight and thin, is not dependent on the position and shape of holes, has high robustness as an acoustic insulator, has stability, has air permeability, does not retain heat, and has excellent manufacturing suitability, and a manufacturing method for the sound insulating structure.

Description

Soundproof structure and method for manufacturing soundproof structure

The present invention relates to a soundproof structure and a method of manufacturing the soundproof structure. Specifically, the soundproof cell includes a frame, a film fixed to the frame, and an opening made of one or more holes perforated in the film. The present invention relates to a soundproof structure that selectively and strongly shields a target frequency sound, and a method of manufacturing a soundproof structure for manufacturing such a soundproof structure.

In general, the sound insulation material shields sound better as the mass is heavier. Therefore, the sound insulation material itself becomes larger and heavier in order to obtain a good sound insulation effect. On the other hand, it is particularly difficult to shield low frequency component sounds. In general, this region is called a mass law, and it is known that the shielding increases by 6 dB when the frequency is doubled.
As described above, most conventional soundproof structures have a drawback that they are large and heavy because sound is insulated by the mass of the structure, and it is difficult to shield at low frequencies.
For this reason, a light and thin sound insulation structure is required as a sound insulation material corresponding to various scenes such as equipment, automobiles, and general homes. Therefore, in recent years, attention has been paid to a sound insulation structure in which a frame is attached to a thin and light membrane structure to control the vibration of the membrane (see Patent Documents 1 and 2).
In the case of this structure, since the principle of sound insulation is a rigidity law different from the above mass law, the low frequency component can be further shielded even with a thin structure. This region is called a rigidity law and behaves the same as when the membrane has a finite size matching the frame opening by fixing the membrane vibration at the frame portion.

In patent document 1, it has the frame body in which the through-hole was formed, and the sound-absorbing material which covers one opening of this through-hole, and the 1st storage elastic modulus E1 of a sound-absorbing material is 9.7x10 ⁶ or more. There is disclosed a sound absorber having a second storage elastic modulus E2 of 346 or less (see summary, claim 1, paragraphs [0005] to [0007], [0034], etc.). The storage elastic modulus of the sound absorbing material means a component stored inside the energy generated in the sound absorbing material due to sound absorption.
In Patent Document 1, in the examples, the peak value of the sound absorption coefficient is 0.5 to 1 without increasing the size of the sound absorber by using a sound absorbing material in which the blended material is resin or a mixture of resin and filler. 0.0, the peak frequency is 290 to 500 Hz, and a high sound absorption effect can be achieved in a low frequency region of 500 Hz or less.

Patent Document 2 discloses an acoustically transparent two-dimensional rigid frame divided into a plurality of individual cells, a sheet of flexible material fixed to the rigid frame, a plurality of weights, A plurality of individual cells are roughly two-dimensional cells, and each weight is fixed to a sheet of flexible material so that each cell is provided with a weight. Are defined by the two-dimensional shape of each individual cell, the flexibility of the flexible material, and each weight thereon, and an acoustic attenuation structure (claims 1 and 12). , And 15, see FIG. 4, column 4, etc.).
Patent Document 2 discloses that this acoustic attenuation panel has the following advantages as compared with the conventional art. (1) The acoustic panel can be made very thin. (2) The acoustic panel can be made very light (low density). (3) Panels can be laminated together to form a wide frequency local resonant acoustic material (LRSM) without obeying the mass law over a wide frequency range, and in particular this deviates from the mass law at frequencies below 500 Hz be able to. (4) Panels can be manufactured easily and inexpensively (see column 5, line 65 to column 6, line 5).

Japanese Patent No. 4832245 US Pat. No. 7,395,898 (corresponding Japanese patent publication: see JP-A-2005-250474)

Incidentally, the sound absorber disclosed in Patent Document 1 is lightweight, has a high sound absorption coefficient peak value as high as 0.5 or higher, and can achieve a high sound absorption effect in a low frequency region where the peak frequency is 500 Hz or less. There was a problem that the selection range of the sound absorbing material was narrow and difficult.
In addition, since the sound absorbing material of such a sound absorbing body completely covers the through hole of the frame body, the sound and the heat cannot easily pass through, and the heat tends to be stored. There was a problem that it was not suitable for sound insulation of cars.
In addition, the sound insulation of the sound absorber disclosed in Patent Document 1 changes gently according to a normal rigidity law or mass law, and therefore, a specific frequency component such as a motor sound often emits strongly in a pulsed manner. It has been difficult to use effectively in equipment and automobiles.

Further, in Patent Document 2, the sound attenuation panel is very thin, lightweight and low in density, can be used at a frequency lower than 500 Hz, can be out of the law of mass density, and can be easily manufactured at low cost. However, the lighter and thinner sound insulation structure required in equipment, automobiles and general households has the following problems.
In the sound attenuating panel disclosed in Patent Document 2, since a weight is essential for the film, the structure is heavy, and it is difficult to use it in equipment, automobiles, general households, and the like.
There is no easy means for placing the weight in each cell structure, and there is no suitability for manufacturing.
Since the shielding frequency and size are strongly dependent on the weight of the weight and the position on the film, the robustness as a sound insulating material is low and there is no stability.
Since the membrane is clearly designated as a non-breathable membrane, it has no ability to transmit wind and heat, and heat tends to be trapped, which is not particularly suitable for sound insulation of equipment and automobiles.

The object of the present invention is to solve the above-mentioned problems of the prior art, lightweight and thin, and the sound insulation properties such as the shielding frequency and size do not depend on the position and shape of the hole, and the robustness as a sound insulation material is high. Soundproof structure that is stable, breathable, can pass wind and heat, has no heat accumulation, is suitable for use in equipment, automobiles and general households, and has excellent manufacturability Another object of the present invention is to provide a method of manufacturing a soundproof structure that can reliably and easily manufacture a soundproof structure.
In the present invention, the term “soundproof” includes both the meanings of “sound insulation” and “sound absorption” as acoustic characteristics. In particular, “sound insulation” refers to “sound insulation”, and “sound insulation” “sounds out”. Including “does not transmit sound”, and therefore “reflects” sound (reflection of sound) and “absorbs” sound (absorption of sound) (Sanseido Ojirin (third edition) ), And http://www.onzai.or.jp/question/soundproof.html and http://www.onzai.or.jp/pdf/new/gijutsu201312_3.pdf ).
In the following, “reflection” and “absorption” are basically referred to as “sound insulation” and “shielding”, and the two are referred to as “reflection” and “absorption”. .

In order to achieve the above object, the soundproof structure of the present invention is a soundproof structure having one or more soundproof cells, each of the one or more soundproof cells being fixed to the frame and a frame each having a through hole. A film and an opening made of one or more holes perforated in the film, both ends of the through-hole of the frame are not closed, and the soundproof structure is a film of one or more soundproof cells A constant frequency centered around the shielding peak frequency, having a shielding peak frequency that is determined due to the opening of one or more soundproofing cells on the lower frequency side than the first natural vibration frequency of the sound and has a maximum transmission loss It is characterized in that the sound of the band is selectively soundproofed.

Here, the one or more soundproof cells are preferably a plurality of soundproof cells arranged two-dimensionally.
The first natural vibration frequency is determined by the geometric shape of the frame of the one or more soundproofing cells and the rigidity of the film of the one or more soundproofing cells, and the shielding peak frequency is the opening of the one or more soundproofing cells. It is preferable to be determined according to the area.
The first natural vibration frequency is determined by the shape and size of the frame of the one or more soundproof cells and the thickness and flexibility of the film of the one or more soundproof cells, and the shielding peak frequency is one or more of the soundproof cells. It is preferable to be determined according to the average area ratio of the openings.
The first natural vibration frequency is preferably included in the range of 10 Hz to 100,000 Hz.

Further, when the radius corresponding to the circle of the frame is R1 (mm), the thickness of the film is t1 (μm), the Young's modulus of the film is E1 (GPa), and the radius of the circle is equivalent to r (μm), It is preferable that the parameter A represented by 1) is 0.07000 or more and 759.1 or less.
A = √ (E1) * (t1 ^1.2 ) * (ln (r) −e) / (R1 ^2.8 ) (1)
Here, e indicates the number of Napiers, and ln (x) is the logarithm of x with e as the base.
In addition, when the equivalent circle radius of the frame is R2 (m), the thickness of the film is t2 (m), the Young's modulus of the film is E2 (Pa), and the density of the film is d (kg / m ³ ), The parameter B represented by 2) is preferably 15.47 or more and 23500 or less.
B = t2 / R2 ² * √ (E2 / d) (2)

Moreover, it is preferable that the opening part of one or more soundproof cells is comprised by one hole.
Moreover, it is preferable that the opening part of one or more soundproof cells is comprised by the several hole of the same size.
Further, when one or more soundproof cells are a plurality of soundproof cells arranged two-dimensionally, it is preferable that 70% or more of the openings of the plurality of soundproof cells are configured by holes of the same size.
In addition, the size of the one or more holes in the opening of the one or more soundproof cells is preferably 2 μm or more.
Moreover, it is preferable that the average size of the frame of one or more soundproof cells is below the wavelength size corresponding to a shielding peak frequency.

Moreover, it is preferable that the one or more holes in the opening of the one or more soundproof cells are holes drilled by a processing method that absorbs energy, and the processing method that absorbs energy is laser processing. preferable.
Moreover, it is preferable that the one or more holes in the opening of the one or more soundproofing cells are holes drilled by a machining method using physical contact, and the machining method is punching or needle processing. Is preferred.

The membrane is preferably impermeable to air.
Moreover, it is preferable that one hole of the opening of the soundproof cell is provided at the center of the film.
The membrane is preferably made of a flexible elastic material.
Further, when one or more soundproof cells are a plurality of soundproof cells arranged two-dimensionally, a plurality of frames of the plurality of soundproof cells are constituted by one frame body arranged so as to be two-dimensionally connected. It is preferred that
Further, when the one or more soundproof cells are a plurality of soundproof cells arranged two-dimensionally, the plurality of films of the plurality of soundproof cells are in the form of a sheet covering a plurality of frames of the plurality of soundproof cells. It is preferable to be constituted by a film body.

In order to achieve the above object, the method for producing a soundproof structure according to the present invention, when producing the soundproof structure, has one or more holes in the opening of one or more soundproof cells in the film of each soundproof cell. It is characterized by drilling by a machining method that absorbs energy or a machining method by physical contact.
Moreover, it is preferable that the processing method which absorbs energy is laser processing, and the machining method is punching or needle processing.

According to the present invention, it is lightweight and thin, and the sound insulation properties such as the frequency and size of the shielding do not depend on the position and shape of the hole, and the robustness as the sound insulation material is high and stable, and the air permeability is good. Therefore, it is possible to provide a soundproof structure suitable for use in equipment, automobiles, and general households, and having excellent manufacturability.
Further, according to the present invention, such a soundproof structure can be reliably and easily manufactured.
In particular, according to the present invention, by providing a very small hole in the film portion of the film structure and the rigidity law shielding structure of the frame, any aimed frequency component can be shielded very strongly, that is, reflected and / or absorbed. .
Further, according to the present invention, it is generally difficult to shield with a thin and light structure, whether it is a mass law or a rigidity law, and a large sound insulation can be performed even in the vicinity of 1000 Hz, which is a region that can be heard loudly by human ears. .

In addition, according to the present invention, a strong sound insulation structure can be realized simply by making a hole in the film.
In addition, according to the present invention, a lighter sound insulation structure can be realized because the weight, which is a cause of increasing the mass, is not required for the acoustic attenuation panel and structure described in Patent Document 2.
In addition, according to the present invention, it is possible to realize a structure in which the film has air permeability due to the presence of the holes, that is, the sound is shielded, that is, reflected and / or absorbed while passing wind or heat.
In addition, according to the present invention, a hole can be easily formed in a film at a high speed by laser processing and punch hole processing, and therefore, it has manufacturability.
Further, according to the present invention, since the sound insulation characteristics hardly depend on the position and shape of the hole, there is an advantage that the stability is high in manufacturing.

It is a top view showing typically an example of soundproof structure concerning one embodiment of the present invention. FIG. 2 is a schematic cross-sectional view taken along line II-II of the soundproof structure shown in FIG. It is a top view which shows typically an example of the soundproof structure which concerns on other embodiment of this invention. It is a top view which shows typically an example of the soundproof structure which concerns on other embodiment of this invention. It is a top view which shows typically an example of the soundproof structure which concerns on other embodiment of this invention. It is a graph which shows the sound insulation characteristic represented by the transmission loss with respect to the frequency of the soundproof structure of Example 1 of this invention. 5 is a graph showing sound insulation characteristics of the soundproof structure of Comparative Example 1. It is a graph which shows the sound insulation characteristic of the soundproof structure of Example 10 of this invention. It is a graph which shows the sound insulation characteristic of the soundproof structure of Example 21 of this invention. It is a graph which shows the sound insulation characteristic of the soundproof structure of Example 5 and 23 of this invention. It is a graph which shows the sound insulation characteristic of the soundproof structure of Example 38 of this invention. It is a graph which shows the shielding frequency with respect to the parameter A of the soundproof structure of this invention. It is a graph which shows the 1st natural vibration frequency with respect to parameter B of the soundproof structure of this invention. 5 is a graph showing sound insulation characteristics of a soundproof structure of Comparative Example 2. It is a graph which shows the absorption characteristic of the soundproof structure of Example 16 of this invention. It is a graph which shows the absorption characteristic of the reference soundproof structure before opening the hole of the soundproof structure of Example 16.

Hereinafter, a soundproof structure and a method for manufacturing the soundproof structure according to the present invention will be described in detail with reference to preferred embodiments shown in the accompanying drawings.
FIG. 1 is a plan view schematically showing an example of a soundproof structure according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view taken along line II-II of the soundproof structure shown in FIG. is there. 3 to 5 are plan views schematically showing an example of a soundproof structure according to another embodiment of the present invention.

The soundproof structure 10 of the present invention shown in FIGS. 1 and 2 has a through-hole 12 and a plurality of two-dimensionally arranged frame bodies 16 that form 16 frames 14 in the illustrated example. A plurality of, in the illustrated example, a sheet-like film body 20 forming 16 films 18 fixed to each frame 14 so as to cover the through holes 12 of the frames 14, and the films 18 in each frame 14 are penetrated. In the illustrated example, there are a plurality of apertures 24 formed by one

hole

22 and 16 openings 24 in the illustrated example.
In the soundproof structure 10, one frame 14, a film 18 fixed to the frame 14, and an opening 24 provided in the film 18 constitute one soundproof cell 26. For this reason, the soundproof structure 10 of the present invention is constituted by a plurality of, in the illustrated example, 16 soundproof cells 26.
The soundproof structure 10 in the illustrated example is configured by a plurality of soundproof cells 26, but the present invention is not limited to this, and includes one frame 14, one film 18, and one opening 24. A single soundproof cell 26 may be used.

The frame 14 is formed so as to be annularly surrounded by a thick plate-like member 15, has a through hole 12 inside, and fixes the film 18 so as to cover the through hole 12 on at least one side. Thus, it becomes a node of membrane vibration of the membrane 18 fixed to the frame 14. Therefore, the frame 14 is higher in rigidity than the film 18. Specifically, both the mass and rigidity per unit area need to be high.
The shape of the frame 14 is preferably a closed continuous shape that can fix the membrane 18 so that the entire outer periphery of the membrane 18 can be suppressed, but the present invention is not limited to this, and the frame 14 As long as it becomes a node of the membrane vibration of the membrane 18 fixed to the substrate, a part thereof may be cut and discontinuous. That is, the role of the frame 14 is to control the membrane vibration by fixing the membrane 18, so that even if there is a small cut in the frame 14 or there is a part that is not very slightly bonded, it is effective. Demonstrate.

Further, the geometric form of the through-hole 12 formed by the frame 14 is a planar shape and is a square in the example shown in FIG. 1, but is not particularly limited in the present invention, and is, for example, a rectangle or a rhombus. Or other quadrilaterals such as parallelograms, regular triangles, isosceles triangles, triangles such as right triangles, regular pentagons, regular polygons such as regular hexagons, circles as shown in FIG. 3, or It may be oval or the like, or may be indefinite.
The size of the frame 14 is the size in plan view and can be defined as the size of the through-hole 12. However, in the case of a regular polygon such as a square shown in FIGS. 1, 4, and 5, or a circle, , The distance between opposing sides passing through its center, or the equivalent circle diameter, and in the case of a polygon, ellipse or indefinite shape, it can be defined as the equivalent circle diameter. In the present invention, the equivalent circle diameter and radius are the diameter and radius when converted into circles having the same area.
In the soundproof structure 10 of the present invention, the size of the frame 14 may be constant in all the frames 14, but may include frames of different sizes (including cases where the shapes are different). In this case, the average size of the frame 14 may be used as the size of the frame 14.

The size of the frame 14 is not particularly limited, and the soundproofing object to which the soundproofing structure 10 of the present invention is applied for soundproofing, for example, a copying machine, a blower, an air conditioner, a ventilation fan, pumps, a generator, and the like. , Ducts, other kinds of industrial equipment such as coating machines, rotating machines, conveyors, etc. that produce sound, transportation equipment such as automobiles, trains, aircraft, refrigerators, washing machines, dryers, TVs What is necessary is just to set according to general household devices, such as John, a copier, a microwave oven, a game machine, an air conditioner, an electric fan, PC, a vacuum cleaner, an air cleaner.
Further, the soundproof structure 10 itself can be used like a partition to be used for the purpose of blocking sounds from a plurality of noise sources. Also in this case, the size of the frame 14 can be selected from the frequency of the target noise.

Although details will be described later, it is preferable to reduce the size of the frame 14 in order to obtain the natural vibration mode of the structure including the frame 14 and the film 18 on the high frequency side.
Although the details of the average size of the frame 14 will be described later, in order to prevent sound leakage due to diffraction at the shielding peak of the soundproof cell 26 by the opening 24 made of a hole provided in the film 18, a shielding peak frequency which will be described later. It is preferable that it is below the wavelength size corresponding to.
For example, the size of the frame 14 is preferably 0.5 mm to 200 mm, more preferably 1 mm to 100 mm, and most preferably 2 mm to 30 mm.
Note that the size of the frame 14 is preferably represented by an average size when different sizes are included in each frame 14.

Further, the width and thickness of the frame 14 are not particularly limited as long as the film 18 can be fixed so as to surely suppress the film 18 and the film 18 can be reliably supported. For example, the width and thickness are set according to the size of the frame 14. be able to.
For example, the width of the frame 14 is preferably 0.5 mm to 20 mm, more preferably 0.7 mm to 10 mm, and more preferably 1 mm to 5 mm when the size of the frame 14 is 0.5 mm to 50 mm. Most preferably.
If the ratio of the width of the frame 14 to the size of the frame 14 becomes too large, the area ratio of the portion of the frame 14 that occupies the whole increases, and the device may become heavy. On the other hand, if the ratio is too small, it is difficult to strongly fix the film with an adhesive or the like at the frame 14 portion.

Further, the width of the frame 14 is preferably 1 mm to 100 mm, more preferably 3 mm to 50 mm, and more preferably 5 mm to 20 mm when the size of the frame 14 is more than 50 mm and 200 mm or less. Most preferred.
The thickness of the frame 14 is preferably 0.5 mm to 200 mm, more preferably 0.7 mm to 100 mm, and most preferably 1 mm to 50 mm.
Note that the width and thickness of the frame 14 are preferably represented by an average width and an average thickness, respectively, when different widths and thicknesses are included in each frame 14.

In the present invention, a plurality of, that is, two or more frames 14 are preferably configured as frame bodies 16 arranged so as to be two-dimensionally connected.
Here, the number of the frames 14 of the soundproof structure 10 of the present invention, that is, in the illustrated example, the number of the frames 14 constituting the frame body 16 is not particularly limited, and the above-described soundproof object of the soundproof structure 10 of the present invention is not limited. It may be set according to Alternatively, since the size of the frame 14 described above is set according to the above-described soundproof object, the number of the frames 14 may be set according to the size of the size of the frame 14.
For example, the number of frames 14 is preferably 1 to 10000, more preferably 2 to 5000, and more preferably 4 to 1000 in the case of noise shielding (reflection and / or absorption) in equipment. Most preferred.

This is because the size of a device is determined with respect to the size of a general device. Therefore, in order to make the size of one soundproof cell 26 suitable for the frequency of noise, a plurality of soundproof cells 26 are used. In many cases, it is necessary to shield, i.e., reflect and / or absorb the frame body 16 with a combination of the above, and on the other hand, if the number of the soundproof cells 26 is increased too much, the total weight of the frame 14 may increase. Because. On the other hand, in a structure like a partition with no restriction on the size, the number of frames 14 can be freely selected according to the required overall size.
Since one soundproof cell 26 has one frame 14 as a structural unit, the number of frames 14 of the soundproof structure 10 of the present invention can also be referred to as the number of soundproof cells 26.

The material of the frame 14, that is, the material of the frame body 16, can support the film 18, has a strength suitable for application to the above-described soundproofing object, and is particularly resistant to the soundproofing environment of the soundproofing object. It is not restrictive and can be selected according to the soundproof object and its soundproof environment. For example, as the material of the frame 14, metal materials such as aluminum, titanium, magnesium, tungsten, iron, steel, chromium, chromium molybdenum, nichrome molybdenum, and alloys thereof, acrylic resin, polymethyl methacrylate, polycarbonate, polyamideid, Polyarylate, polyetherimide, polyacetal, polyetheretherketone, polyphenylene sulfide, polysulfone, polyethylene terephthalate, polybutylene terephthalate, polyimide, resin material such as triacetylcellulose, carbon fiber reinforced plastic (CFRP), carbon fiber, glass Examples thereof include fiber reinforced plastic (GFRP).
Further, a plurality of types of materials of these frames 14 may be used in combination.

The film 18 is fixed to the frame 14 so as to cover the through-hole 12 inside the frame 14, and absorbs or reflects sound wave energy by vibrating the film in response to sound waves from the outside. And soundproofing. Therefore, the membrane 18 is preferably impermeable to air.
By the way, since it is necessary for the membrane 18 to vibrate with the frame 14 as a node, the membrane 18 is fixed to the frame 14 so as to be surely suppressed, becomes an antinode of membrane vibration, and needs to absorb or reflect sound wave energy to prevent sound. There is. For this reason, the membrane 18 is preferably made of a flexible elastic material.
For this reason, the shape of the film 18 is the shape of the through hole 12 of the frame 14, and the size of the film 18 is the size of the frame 14, more specifically, the size of the through hole 12 of the frame 14. Can do.

Here, as shown in FIGS. 6 to 11, the film 18 fixed to the frame 14 of the soundproof cell 26 has a minimum transmission loss, for example, 0 dB as a resonance frequency which is the frequency of the lowest natural vibration mode. The first natural vibration frequency is as follows. In the present invention, the first natural vibration frequency is determined by the structure formed by the frame 14 and the membrane 18, and therefore, as shown in FIGS. 6 and 7, the hole 22 drilled in the membrane 18, and hence the opening 24. It has been found by the present inventors that the values are substantially the same regardless of the presence or absence. 6 to 11 are graphs showing the sound insulation characteristics of the soundproof structures of Example 1, Comparative Example 1, and Examples 10, 21, 5, and 23 and 38 of the present invention, which will be described later, respectively. It represents the transmission loss with respect to frequency.
Here, in the structure composed of the frame 14 and the film 18, that is, the first natural vibration frequency of the film 18 fixed so as to be restrained by the frame 14, the sound wave is the frequency where the sound wave shakes the film vibration most due to the resonance phenomenon. It is the frequency of the natural vibration mode that is greatly transmitted at.

In addition, according to the knowledge of the present inventors, in the soundproof structure 10 of the present invention, since the hole 18 constituting the opening portion 24 including the hole 22 is drilled in the film 18 as a through hole, the first A sound wave shielding peak in which transmission loss peaks (maximum) appears at a shielding peak frequency lower than the natural vibration frequency. In particular, an increase in sound absorption is observed due to the presence of the through-hole 22 on the low frequency side from the shielding peak caused by the through-hole 22.
Therefore, since the soundproof structure 10 of the present invention has a peak (maximum) of shielding (transmission loss) at the shielding peak frequency, it is possible to selectively prevent sound in a certain frequency band centered on the shielding peak frequency. .
In the present invention, first, sound shielding can be increased and the peak of the shielding can be controlled. In addition to this, sound (sound wave energy) is absorbed by the effect of the through-hole 22. Has a feature that appears on the lower frequency side.

For example, in the example shown in FIG. 6, the first natural vibration frequency is 2820 Hz in the audible range, and shows a shielding peak at which transmission loss has a peak value of 35 dB at a shielding peak frequency of 1412 Hz on the lower frequency side. A certain frequency band centered at 1412 Hz in the audible range can be selectively insulated.
In each example shown in FIGS. 8 to 11, 3162 Hz, 708 Hz, 2000 Hz, and 1258 Hz on the low frequency side and in the audible range with respect to the first natural vibration frequencies of 5620 Hz, 2818 Hz, 2820 Hz, and 2820 Hz in the audible range, respectively. The transmission loss shows 40, 72, 29, 37, and 70 at the shielding peak frequency, which indicates that a certain frequency band centered on each shielding peak frequency can be selectively shielded.
In addition, the measuring method of the transmission loss (dB) in the soundproof structure of this invention is mentioned later.

For this reason, in the structure composed of the frame 14 and the film 18, in order to set the shielding peak frequency depending on the opening 24 composed of one or more holes 22 to an arbitrary frequency within the audible range, the natural vibration mode is set as high as possible. It is important to obtain, especially in practical use. For this purpose, it is preferable to increase the thickness of the film 18, preferably to increase the Young's modulus of the material of the film 18, and to reduce the size of the frame 14, and thus the size of the film 18, as described above. Etc. are preferable. That is, in the present invention, these preferable conditions are important.

Therefore, the soundproof structure 10 of the present invention complies with the rigidity law, and since the sound wave is shielded at a frequency lower than the first natural vibration frequency of the film 18 fixed to the frame 14, the first natural vibration frequency of the film 18 is It is preferably 10 Hz to 100000 Hz corresponding to a human sound wave detection range, more preferably 20 Hz to 20000 Hz, which is a human sound wave audible range, still more preferably 40 Hz to 16000 Hz, and even more preferably 100 Hz to Most preferably, it is 12000 Hz.

The thickness of the film 18 is not particularly limited as long as the film can vibrate in order to absorb or reflect sound wave energy to prevent sound. However, the thickness of the film 18 is increased to obtain a natural vibration mode on the high frequency side. It is preferable. For example, in the present invention, the thickness of the film 18 can be set according to the size of the frame 14, that is, the size of the film.
For example, the thickness of the film 18 is preferably 0.005 mm (5 μm) to 5 mm, and preferably 0.007 mm (7 μm) to 2 mm when the size of the frame 14 is 0.5 mm to 50 mm. More preferably, the thickness is 0.01 mm (10 μm) to 1 mm.
Further, the thickness of the film 18 is preferably 0.01 mm (10 μm) to 20 mm, and preferably 0.02 mm (20 μm) to 10 mm when the size of the frame 14 is more than 50 mm and 200 mm or less. Is more preferable, and 0.05 mm (50 μm) to 5 mm is most preferable.
Note that the thickness of the film 18 is preferably expressed as an average thickness when the thickness of one film 18 is different, or when the thickness of each film 18 is different.

Here, in the soundproof structure 10 of the present invention, the first natural vibration frequency of the film 18 in the structure composed of the frame 14 and the film 18 is the geometric form of the frame 14 of the plurality of soundproof cells 26, for example, the shape of the frame 14 and It can be determined by the size (size) and the rigidity of the membrane of the plurality of soundproof cells, for example, the thickness and flexibility of the membrane.
As a parameter characterizing the first natural vibration mode of the film 18, in the case of the film 18 of the same material, a ratio of the thickness (t) of the film 18 and the square of the size (a) of the frame 14, for example, In the case of a regular square, a ratio [a ² / t] to the size of one side can be used. When this ratio [a ² / t] is equal, for example, (t, a) is (50 μm, 7. 5 mm) and (200 μm, 15 mm), the first natural vibration mode has the same frequency, that is, the same first natural vibration frequency. That is, by setting the ratio [a ² / t] to a constant value, the scaling rule is established, and an appropriate size can be selected.

The Young's modulus of the film 18 is not particularly limited as long as the film 18 has elasticity capable of vibrating the film in order to absorb or reflect sound wave energy to prevent sound. It is preferable to increase the size in order to obtain a higher frequency. For example, in the present invention, the Young's modulus of the film 18 can be set according to the size of the frame 14, that is, the size of the film.
For example, the Young's modulus of the film 18 is preferably 1000 Pa to 3000 GPa, more preferably 10,000 Pa to 2000 GPa, and most preferably 1 MPa to 1000 GPa.

Further, the density of the film 18 is not particularly limited as long as the film 18 can vibrate in order to absorb or reflect sound wave energy to prevent sound. For example, the density of the film 18 is 10 kg / m ³ to 30000 kg / m ^3. is ^preferably, more preferably from ^{100kg / m 3 ~ 20000kg / m} 3, most preferably ^{500kg / m 3 ~ 10000kg / m} 3.

When the material of the film 18 is a film-like material or a foil-like material, the film 18 has strength suitable for application to the above-described soundproofing object, and is resistant to the soundproofing environment of the soundproofing object. As long as the film can vibrate in order to absorb or reflect sound wave energy to prevent sound, it is not particularly limited and can be selected according to the soundproof object and its soundproof environment. For example, the material of the film 18 includes polyethylene terephthalate (PET), polyimide, polymethyl methacrylate, polycarbonate, acrylic (PMMA), polyamideide, polyarylate, polyetherimide, polyacetal, polyetheretherketone, polyphenylene sulfide, polysulfone. , Polyethylene terephthalate, polybutylene terephthalate, polyimide, triacetyl cellulose, polyvinylidene chloride, low density polyethylene, high density polyethylene, aromatic polyamide, silicone resin, ethylene ethyl acrylate, vinyl acetate copolymer, polyethylene, chlorinated polyethylene , Resin materials that can be made into a film such as polyvinyl chloride, polymethylpentene, polybutene, aluminum, chromium, titanium, stainless steel, Metal materials that can be made into foil, such as nickel, tin, niobium, tantalum, molybdenum, zirconium, gold, silver, platinum, palladium, iron, copper, permalloy, paper, cellulose, and other fibrous film materials, non-woven fabric, nano Examples include materials or structures capable of forming a thin structure, such as a film containing a size fiber, a porous material such as urethane and cinsalate processed thinly, and a carbon material processed into a thin film structure.

The film 18 may be individually fixed to each of the plurality of frames 14 of the frame body 16 of the soundproof structure 10 to constitute a sheet-like film body 20 as a whole. A film 18 that covers each frame 14 may be formed by a single sheet-like film body 20 that is fixed so as to cover the frame. Alternatively, as an intermediate between them, a sheet-like film body is fixed to a part of the frames 14 so as to cover a part of the plurality of frames 14, and a film 18 that covers each frame 14 is formed. You may comprise the sheet-like film body 20 which covers the whole some frame 14 (all the frames 14) using some bodies.

The film 18 is fixed to the frame 14 so as to cover the opening on at least one side of the through hole 12 of the frame 14. That is, the film 18 may be fixed to the frame 14 so as to cover the opening on one side, the other side, or both sides of the through hole 12 of the frame 14.
Here, all the films 18 may be provided on the same side of the through holes 12 of the plurality of frames 14 of the soundproof structure 10, or some of the films 18 may be part of the through holes 12 of the plurality of frames 14. A part of the film 18 may be provided on one side, and the other part of the remaining part of the through holes 12 of the plurality of frames 14 may be provided with the remaining film 18. The films provided on one side, the other side, and both sides of the through-hole 12 may be mixed.

The method of fixing the film 18 to the frame 14 is not particularly limited, and any method may be used as long as the film 18 can be fixed to the frame 14 so as to be a node of film vibration. For example, a method using an adhesive or a physical And a method using a typical fixture.
In the method using an adhesive, the adhesive is applied on the surface surrounding the through hole 12 of the frame 14, the film 18 is placed thereon, and the film 18 is fixed to the frame 14 with the adhesive. Examples of the adhesive include an epoxy adhesive (araldite, etc.), a cyanoacrylate adhesive (Aron Alpha, etc.), an acrylic adhesive, and the like.
As a method using a physical fixing tool, a film 18 arranged so as to cover the through hole 12 of the frame 14 is sandwiched between the frame 14 and a fixing member such as a rod, and the fixing member is fixed with a screw or a screw. The method of fixing to the frame 14 using a tool etc. can be mentioned.

The membrane 18, that is, the soundproof cell 26, has an opening 24 composed of one or more holes 22.
Here, in the present invention, as shown in FIGS. 6 and 8 to 11, the soundproof structure 10 has an opening 24 composed of one or more holes 22 perforated in the film 18, whereby the film 18. There is a transmission loss peak at which the shielding becomes a peak (maximum) on the lower frequency side than the first natural vibration frequency, and the frequency at which this shielding (transmission loss) becomes a peak (maximum) is called a shielding peak frequency.

This shielding peak frequency appears due to the hole 22 of the opening 24 on the lower frequency side than the first natural vibration frequency that mainly depends on the film 18 of the soundproof cell 26 of the soundproof structure 10. The shielding peak frequency is determined by the size of the opening 24 with respect to the size of the frame 14 (or the film 18), specifically, the total of the holes 22 with respect to the area of the through hole 12 (or the film 18 covering the through hole 12) of the frame 14. It is determined according to the opening ratio of the opening 24 which is the area ratio.

Here, as shown in FIG. 4, one or more holes 22 may be perforated in the film 18 covering the through-hole 12 of the soundproof cell 26. Further, as shown in FIGS. 1 to 3 and 5, the drilling position of the hole 22 may be in the middle of the soundproof cell 26 or the membrane 18 (hereinafter represented by the soundproof cell 26). However, as shown in FIG. 4, it is not necessary to be in the middle of the soundproof cell 26, and any position may be used.
That is, simply changing the drilling position of the hole 22 does not change the sound insulation characteristic of the soundproof structure 10 of the present invention.

Further, the number of the holes 22 constituting the opening 24 in the soundproof cell 26 may be one for one soundproof cell 26 as shown in FIGS. 1 to 3 and FIG. The present invention is not limited to this, and may be two or more (ie, a plurality) as shown in FIG.
Here, in the soundproof structure 10 of the present invention, from the viewpoint of air permeability, the opening 24 of each soundproof cell 26 is constituted by one hole 22 as shown in FIGS. 1 to 3 and FIG. Is preferred. The reason is that, when the aperture ratio is constant, the ease of passage of air as wind is greater when one hole is large and the viscosity at the boundary does not work greatly.

On the other hand, when there are a plurality of holes 22 in one soundproof cell 26, the sound insulation characteristic of the soundproof structure 10 of the present invention is the sound insulation characteristic corresponding to the total area of the plurality of holes 22, that is, the area of the opening 24, That is, the corresponding sound insulation peak is shown at the corresponding sound insulation peak frequency. Therefore, as shown in FIG. 4, the area of the opening 24, which is the total area of the plurality of holes 22 in one soundproof cell 26 (or film 18), is within the other soundproof cell 26 (or film 18). It is preferable to be equal to the area of the opening 24 which is the area of the hole 22 having only one, but the present invention is not limited to this.
If the aperture ratio of the opening 24 in the soundproof cell 26 (the area ratio of the opening 24 to the area of the film 18 covering the through-hole 12 (the ratio of the total area of all the holes 22)) is the same. Since the same soundproof structure 10 is obtained with the single hole 22 and the plurality of holes 22, soundproof structures of various frequency bands can be produced even if the hole 22 is fixed to a certain size.

In the present invention, the aperture ratio (area ratio) of the opening 24 in the soundproof cell 26 is not particularly limited, and may be set according to the sound insulation frequency band to be selectively insulated, but is 0.000001%. It is preferably from ˜70%, more preferably from 0.000005% to 50%, and preferably from 0.00001% to 30%. By setting the aperture ratio of the opening 24 within the above range, it is possible to determine the sound insulation peak frequency and the transmission loss of the sound insulation peak, which are the center of the sound insulation frequency band to be selectively insulated.

The soundproof structure 10 of the present invention preferably has a plurality of holes 22 of the same size in one soundproof cell 26 from the viewpoint of manufacturability. In other words, the opening 24 of each soundproof cell 26 is preferably composed of a plurality of holes 22 of the same size.
Furthermore, in the soundproof structure 10 according to the present invention, it is preferable that the holes 22 constituting the openings 24 of all the soundproof cells 26 have the same size.

In the present invention, the hole 22 is preferably drilled by a processing method that absorbs energy, for example, laser processing, or by a machining method by physical contact, for example, punching or needle processing.
For this reason, if a plurality of holes 22 in one soundproof cell 26 or one or a plurality of holes 22 in all soundproof cells 26 have the same size, holes are formed by laser processing, punching, or needle processing. In some cases, it is possible to continuously drill holes without changing the setting of the processing apparatus and the processing strength.

Further, as shown in FIG. 5, in the soundproof structure 10 of the present invention, the size (size) of the hole 22 in the soundproof cell 26 (or film 18) is different for each soundproof cell 26 (or film 18). May be. When there is a hole 22 having a different size for each soundproof cell 26 (or film 18) as described above, the sound insulation characteristic corresponding to the average area obtained by averaging the areas of the holes 22, that is, the corresponding sound insulation peak frequency corresponds. This shows the sound insulation peak.
Moreover, it is preferable that 70% or more of the opening 24 of each soundproof cell 26 of the soundproof structure 10 of this invention is comprised with the hole of the same size.

The size of the hole 22 constituting the opening 24 is not particularly limited as long as it can be appropriately drilled by the above-described processing method.
However, the size of the hole 22 on the lower limit side is 2 μm from the viewpoint of manufacturing suitability such as laser processing accuracy such as laser aperture accuracy, processing accuracy such as punching processing or needle processing, and ease of processing. Preferably, it is preferably 5 μm or more, and most preferably 10 μm or more.
In addition, since the upper limit value of the size of these holes 22 needs to be smaller than the size of the frame 14, the size of the frame 14 is usually in the order of mm, and if the size of the hole 22 is set to the μm order, The upper limit value of the size of the hole 22 does not exceed the size of the frame 14, but if it exceeds, the upper limit value of the size of the hole 22 may be set to be equal to or smaller than the size of the frame 14.

By the way, in the soundproof structure 10 of the present invention, the first natural vibration frequency is determined by the structure composed of the frame 14 and the film 18, and the shielding peak frequency at which the transmission loss peaks is a film having the structure composed of the frame 14 and the film 18. It depends on the opening made of the hole 22 perforated.
Here, in the soundproof structure 10 of the present invention, the inventors set R1 (mm) as the equivalent circle radius of the soundproof cell 26, that is, the frame 14, the thickness of the film 18 as t1 (μm), and the Young's modulus of the film 18. When E1 (GPa) and the equivalent circle radius of the opening 24 are r (μm), the parameter A represented by the following formula (1) and the shielding peak vibration frequency (Hz) of the soundproof structure 10 are the soundproof cell. When the equivalent circle radius R1 (mm) of 26, the thickness t1 (μm) of the film 18, the Young's modulus E1 (GPa) of the film 18, and the equivalent circle radius r (μm) of the opening 24 are changed, FIG. As shown, it has a substantially linear relationship, is represented by a substantially linear expression, and has been found to ride on a substantially identical straight line in two-dimensional coordinates. It was also found that the parameter A does not substantially depend on the film density and Poisson's ratio.
A = √ (E1) * (t1 ^1.2 ) * (ln (r) −e) / (R1 ^2.8 ) (1)
Here, e indicates the number of Napiers, and ln (x) is the logarithm of x with e as the base.
Here, when there are a plurality of openings 24 in the soundproof cell 26, the circle equivalent radius r is obtained from the total area of the plurality of openings.

FIG. 12 is obtained from a simulation result in a design stage before an experiment of an example described later.
In the soundproof structure 10 of the present invention, when the first natural vibration frequency is 10 Hz to 100,000 Hz, the shield peak vibration frequency is a main fraction less than or equal to the first natural vibration frequency, so the shield peak vibration frequency is from 10 Hz to 100,000 Hz. Table 1 shows values of the parameter A corresponding to a plurality of values.

As is apparent from Table 1, the parameter A corresponds to the first natural vibration frequency. Therefore, in the present invention, it is preferably 0.07000 or more and 759.1 or less, and is 0.1410 to 151.82. More preferably, it is more preferably 0.2820 to 121.5, and most preferably 0.7050 to 91.09.
By using the parameter A normalized as described above, the shielding peak frequency can be determined in the soundproof structure of the present invention, and the sound in a certain frequency band centered on the shielding peak frequency is selectively insulated. be able to. Conversely, by using this parameter A, it is possible to set the soundproof structure of the present invention having a shielding peak frequency that is the center of a frequency band to be selectively sound-insulated.

In addition, in the soundproof structure 10 of the present invention, the present inventors set the soundproof cell 26, that is, the frame 14 to have a circle equivalent radius R2 (m), the thickness of the film 18 t2 (m), and the Young's modulus of the film 18 E2. (Pa) When the density of the film 18 is d (kg / m ³ ), the parameter B (√m) represented by the following formula (2), the frame 14 of the soundproof structure 10 and the film 18 are used. The first natural vibration frequency (Hz) is a circle-equivalent radius R2 (m) of the soundproof cell 26, a thickness t2 (m) of the film 18, a Young's modulus E2 (Pa) of the film 18, and a density d (kg / kg) of the film 18. It was found that even when m ³ ) was changed, the relationship was approximately linear, and as shown in FIG. 13, it was expressed by the following expression (3).
B = t2 / R2 ² * √ (E2 / d) (2)
y = 0.7278x ^0.9566 (3)
Here, y is the first natural vibration frequency (Hz), and x is the parameter B.
Note that FIG. 13 is obtained from the result of simulation in the design stage before the experiment of an example described later.

From the above, in the soundproof structure 10 of the present invention, the equivalent circle radius R2 (m) of the soundproof cell 26, the thickness t2 (m) of the film 18, the Young's modulus E2 (Pa) of the film 18, and the density d (kg) of the film 18 / M ³ ) is normalized by the parameter B (√m), the point representing the relationship between the parameter B and the first natural vibration frequency (Hz) of the soundproof structure 10 on the two-dimensional (xy) coordinates is It is expressed by the above formula (3) that can be regarded as a substantially linear expression, and it can be seen that all points are on substantially the same straight line. Note that R2 and R1 both represent the circle-equivalent radius of the soundproof cell 26, but have a relationship of R2 = 10 ³ × R1. Further, t2 and t1 both represent the thickness of the film 18, but have a relationship of t2 = 10 ⁶ × t1. E2 and E1 both represent the Young's modulus of the film 18, but have a relationship of E1 = 10 ⁹ × E2.
Table 2 shows parameter B values for a plurality of values of the first natural vibration frequency between 10 Hz and 100,000 Hz.

As is apparent from Table 2, the parameter B corresponds to the first natural vibration frequency, and therefore, in the present invention, 1.547 × 10 (= 15.47) or more and 2.350 × 10 ⁵ (23500) or less. It is preferably 3.194 × 10 (= 31.94) to 4.369 × 10 ⁴ (43960), more preferably 6.592 × 10 (= 65.92) to 3.460 ×. preferably more than it is 10 ⁴ (34600), and most preferably ^{1.718 × 10 2 (= 171.8)} ~ 2.562 × 10 4 (25620).
By using the parameter B standardized as described above, the first natural vibration frequency that is the upper limit on the high frequency side of the shielding peak frequency in the soundproof structure of the present invention can be determined, and the frequency that should be selectively sound-insulated. The shielding peak frequency that becomes the center of the band can be determined. Conversely, by using this parameter B, it is possible to set the soundproof structure of the present invention having the first natural vibration frequency that can have the shielding peak frequency that is the center of the frequency band to be selectively sound-insulated. it can.

In the soundproofing of the soundproofing structure of the present invention, it is important that both the through hole 22 through which sound can be transmitted as an acoustic wave instead of vibration and the film 18 through which sound passes as membrane vibration are important.
Therefore, the through-hole 22 through which sound can be transmitted obtains a sound insulation peak in the same manner as when the sound is opened even when the sound is not covered by a membrane vibration but is covered with a member that can pass through as an acoustic wave transmitted through the air. be able to. Such a member is generally a breathable member.
As a representative member having such air permeability, a screen door screen can be cited. As an example, an amidology 30 mesh product manufactured by NBC Meshtec Co., Ltd. can be cited, but the present inventors have confirmed that the spectrum obtained by closing the through hole 22 does not change.

The net may have a lattice shape or a triangular lattice shape, and is not particularly limited or limited by the shape. The size of the entire net may be larger or smaller than the size of the frame of the present invention. Further, the size of the net may be a size that covers the through holes 22 of the film 18 one by one. Moreover, the net | network may be a net | network of the size for the purpose of what is called an insect repellent, and the net | network which prevents a finer sand from approaching. The material may be a net made of synthetic resin, or a wire for crime prevention or radio wave shielding.
In addition, the air-permeable member described above is not limited to a screen door mesh, but besides a mesh, a non-woven material, a urethane material, cinsalate (manufactured by 3M), breath air (manufactured by Toyobo), dot air (Toray Industries, Inc.) Etc.). In the present invention, by covering with a material having such air permeability, it is possible to prevent insects and sand from entering from the hole, to ensure privacy such that the inside can be seen from the through hole 22, and to conceal. Sex can be imparted.
The soundproof structure of the present invention is basically configured as described above.

Since the soundproof structure of the present invention is configured as described above, it enables low-frequency shielding, which has been difficult in the conventional soundproof structure, and further adapts to noise of various frequencies from low frequencies to frequencies exceeding 1000 Hz. It also has the feature that it can design a structure that provides strong sound insulation. In addition, since the soundproof structure of the present invention is a sound insulation principle that does not depend on the mass (mass law) of the structure, it is possible to realize a very light and thin sound insulation structure compared to the conventional soundproof structure. Therefore, it can be applied to a soundproofing object for which sufficient sound insulation is difficult.

In addition, the soundproof structure of the present invention is a sound insulating structure that does not require a weight, is suitable for manufacturing only by providing a hole in the film, and has high robustness as a sound insulating material, as in the technique described in Patent Document 2. Have That is, the soundproof structure of the present invention has the following characteristics as compared with the technique described in Patent Document 2.
1. Since a weight that was a cause of increasing the mass is not necessary, a lighter sound insulation structure can be realized.
2. Since the film can be punched at high speed and easily by laser processing or punch holes, it has manufacturability.
3. Since the sound insulation characteristics hardly depend on the position and shape of the hole, stability in manufacturing is high.
4). The presence of the hole makes it possible to realize a structure in which the membrane has air permeability, that is, a sound is shielded while passing wind and heat.

The soundproof structure of the present invention is manufactured as follows.
First, a plurality of, for example, a frame body 16 having 225 frames 14 and a sheet-like film body 20 that covers all the through holes 12 of all the frames 14 of the frame body 16 are prepared.
Next, the sheet-like film body 20 is fixed to all the frames 14 of the frame body 16 with an adhesive, and the films 18 that respectively cover the through holes 12 of all the frames 14 are formed. A plurality of soundproof cells having the following structure are formed.
Next, one or more holes 22 are respectively drilled in the individual films 18 of the plurality of soundproof cells by a processing method that absorbs energy such as laser processing, or a mechanical processing method that uses physical contact such as punching or needle processing. Thus, the opening 24 is formed in each soundproof cell 26.
Thus, the soundproof structure 10 of the present invention can be manufactured.
The manufacturing method of the soundproof structure of the present invention is basically configured as described above.

The soundproof structure and the method of manufacturing the soundproof structure of the present invention will be specifically described based on examples.
The design of the soundproof structure will be described before the experiment of manufacturing the embodiment of the present invention and measuring the acoustic characteristics.
Since this soundproof structure system is an interaction system between membrane vibration and sound waves in the air, analysis was performed using a coupled analysis of sound and vibration. Specifically, the design was performed using an acoustic module of COMSOL ver5.0 which is analysis software of the finite element method. First, the first natural vibration frequency was obtained by natural vibration analysis. Next, acoustic structure coupling analysis by frequency sweep was performed in the boundary of the periodic structure, and transmission loss at each frequency with respect to the sound wave incident from the front was obtained.
Based on this design, the shape and material of the sample were determined. The shielding peak frequency in the experimental result agrees well with the prediction from the simulation.

In addition, acoustic structure coupled analysis simulation was performed to determine the correspondence between the shielding peak frequency and each physical property. As parameters A, the thickness t1 (μm) of the film 18, the size (or radius) R1 (mm) of the frame 14, the Young's modulus E1 (GPa) of the film, and the equivalent circle radius r (μm) of the opening are changed. The transmission loss at each frequency was determined, and the shielding peak frequency was determined. The results are shown in FIG. The present inventors have found from this calculation that the shielding peak frequency is approximately proportional to √ (E1) * (t1 ^1.2 ) * (ln (r) −e) / (R1 ^2.8 ). Therefore, it was found that the shielding peak frequency can be predicted by setting the parameter A = √ (E1) * (t1 ^1.2 ) * (ln (r) −e) / (R1 ^2.8 ).

In addition, the correspondence between the first natural vibration frequency and each physical property was obtained by taking advantage of the characteristics of the simulation that can freely change the material characteristics and the film thickness. By changing the thickness t2 (m) of the film 18, the size (or radius) R2 (m) of the frame 14, the Young's modulus E2 (Pa) of the film, and the density d (kg / m ³ ) of the film as parameters B Asked. The results are shown in FIG. The present inventors have found that the first natural vibration frequency f_resonance is approximately proportional to t2 / R2 ² * √ (E2 / d) by this calculation. Therefore, it was found that the natural vibration can be predicted by setting the parameter B = t2 / R2 ² * √ (E2 / d).

(Example 1)
Hereinafter, the PET film thickness of the film 18 is 50 μm (= 50 × 10 ⁻⁶ m), the size of the frame 14 is 7.5 mm (= 7.5 × 10 ⁻³ m), and the size diameter is 200 μm (= 200 × 10 ^−6). The manufacturing method of the soundproof structure of Example 1 which has the hole 22 of m) is shown.
A 50 μm PET film (Lumirror manufactured by Toray Industries, Inc.) was used as the film 18. As the frame 14, an aluminum thickness of 3 mm × width of 3 mm was used, and the shape of the frame 14 was a square, and one processed through the square through-hole 12 having a side of 7.5 mm was used. The through holes 12 of the frame structure have a total of 225 pieces of 15 × 15 pieces. This frame structure was fixed to the PET film with an adhesive, and a frame / membrane structure composed of the frame 14 and the film 18 was produced.

The step of making the hole 22 in the film 18 having the frame / film structure was performed as follows.
First, black dots were drawn on the film 18 for the purpose of light absorption using black ink. At this time, the size of the black spot was set as close as possible to the size of the hole to be opened.
Next, the black spot portion of the film was irradiated with a green laser (300 mW) of a laser device (a laser diode manufactured by Nichia Corporation).
Since the visible light absorptance of the PET film was sufficiently small, the laser was absorbed only in the black spot portion to generate heat of absorption, and finally a hole 22 was opened in the black spot portion. When the size of the hole 22 was measured using an optical microscope (Nikon Corporation ECLIPSE), a circular hole diameter of 200 μm could be obtained at the center of the frame 14. Thereby, the soundproof structure of Example 1 of this invention was able to be manufactured.

The acoustic characteristics were measured by the transfer function method using four microphones in a self-made aluminum acoustic tube. This method conforms to “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 that of WinZac manufactured by Nittobo Acoustic Engineering Co., Ltd. was used. With this method, sound transmission loss can be measured in a wide spectral band. The soundproof structure of Example 1 was placed at the measurement site of the acoustic tube, and sound transmission loss was measured in the range of 10 Hz to 40000 Hz. This measurement range is measured by combining a plurality of acoustic tube diameters and distances between microphones.
In general, as the distance between the microphones increases, the measurement noise at the low frequency becomes smaller. On the other hand, if the distance between the microphones is longer than the wavelength / 2 on the high frequency side, the measurement becomes impossible in principle. Therefore, the measurement was performed a plurality of times while changing the distance between the microphones. In addition, since the acoustic tube is thick, it becomes impossible to measure due to the influence of the higher-order mode on the high frequency side. Therefore, the measurement was performed using a plurality of types of acoustic tube diameters.

The measurement result of the transmission loss is shown in FIG.
As is clear from the results shown in FIG. 1, it was found that extremely strong shielding occurred in the vicinity of 1000 Hz.
Hereinafter, since the measurement methods are the same in all of Examples 2 to 42 and Comparative Examples 1 and 2, methods for preparing samples of each Example and each Comparative Example are shown.
The shape, size and material of the frame 14 of each of the soundproof structures of Examples 1 to 42 and Comparative Examples 1 and 2 manufactured, the type, thickness and first natural vibration frequency of the film 18, and the size, shape and number of the holes 22 Tables 3 to 5 show the maximum or maximum shielding peak frequency (hereinafter also simply referred to as shielding frequency), the transmission loss, and the values of parameters A and B of the spectra obtained in the examples and the comparative examples. Shown in

(Comparative Example 1)
The frame / membrane structure produced in Example 1 was measured using the same frame / membrane structure without making a hole. The results are shown in Table 3. Moreover, the measurement result of transmission loss is shown in FIG. Sound insulation by general mass law and rigidity law was obtained. It can be seen that this switching occurs near 2820 Hz, which matches the first natural vibration frequency of the membrane.
(Comparative Example 2)
With respect to the film | membrane (PET film 50 micrometers) used in Example 1, the hole was opened at 7.5 mm space | interval, without attaching a frame. The diameter of the hole was set to 200 μm in accordance with Example 1. The results are shown in Table 3, and the measurement results of the transmission loss are shown in FIG. In general, a structure with a hole in the plate is easier to pass at lower frequencies and more difficult to pass at higher frequencies, and this experiment has obtained its characteristics. At this time, neither the first natural vibration frequency nor the shielding peak is observed.
In the calculation of the parameters A and B in the table, since there is no frame, the radius R of the frame was calculated as infinite (R → ∞).

(Examples 2 to 7)
A frame / film structure was prepared in the same manner as in Example 1. Since it is known that the amount of heat generated can be changed by changing the laser irradiation time and the size of the hole 22 can be changed, the laser irradiation time / power is optimized so that 20 μm can be formed on the PET film. The desired hole 22 of up to 2000 μm could be obtained. Table 3 shows the results including the shielding frequency in the soundproof structure of each example obtained in this way. The sound insulation characteristics of Example 5 are indicated by dotted lines in FIG.

(Example 8)
In the same manner as in Example 1, after preparing the frame / membrane structure, instead of forming the hole 22 by laser irradiation, the hole 22 was physically formed by inserting a needle into the film. A hole 22 having a diameter of 200 μm could be obtained by adjusting the force. The shielding spectrum (transmission loss) of Example 8 obtained in this way was obtained without changing from Example 1. The results are shown in Table 3.

(Examples 9 to 11)
The thickness of the PET film used in Example 1 was changed from a 50 μm product to a 20 μm, 100 μm, and 200 μm product, and a soundproof structure with a hole diameter of 200 μm was obtained using the same manufacturing method. Table 3 shows the measurement results of the examples thus obtained.
As the film thickness increases, the bending rigidity increases, and accordingly, the first vibration mode of the natural vibration shifts to a high frequency. Accordingly, the shielding frequency at the same hole diameter also shifted to a high frequency. FIG. 8 shows the shielding spectrum of Example 10 having a thickness of 100 μm.

(Examples 12 to 17)
A soundproof structure sample was produced under the same conditions as in Example 1 except that the frame size was changed. Processing was performed with one side of the square through-hole 12 being 15 mm. The frame 14 itself is the same as thickness 3 mm × width 3 mm. The through holes 12 of the frame 14 of the frame body 16 have a total of 64 of 8 × 8. Similarly to Example 1, the holes 22 were processed with a laser, and the holes 22 having different hole sizes (20, 100, 200, 400, 1000, and 2000 μm) were obtained by adjusting the irradiation time and power. The measurement results of Examples 12 to 15 thus obtained are shown in Table 3, and the measurement results of Examples 16 to 17 are shown in Table 4.
In addition, the absorption factor of the sound (energy of sound waves) of the soundproof structure sample of Example 16 was obtained. The measurement method was the transfer function method using the same four microphones as in Example 1, and the absorptance was obtained from the measured transmittance and reflectance. Here, the absorption rate can be obtained from the following equation. The result is shown in FIG.
Absorptivity = 1-Transmittance-Reflectance For comparison, the sound absorptivity of the reference soundproof structure sample without the hole 22 before the hole 22 in the middle of making the soundproof structure sample of Example 16 is drilled. Was also measured. The result is shown in FIG.

(Examples 18 to 19)
In the case of the same material, the first natural vibration frequency is a frequency that is almost close when the ratio of the square of the thickness to the length of one side of the square is constant. A soundproof structure sample was produced in the same manner as in Example 1 except that the PET film had a thickness of 200 μm. The size of the hole 22 was adjusted so that Example 18 had a diameter of 200 μm and Example 19 had a diameter of 400 μm. Table 4 shows the measurement results of each example thus obtained. The first solid vibration frequency was obtained as 2820 Hz in the same manner as in Example 1, and a large shielding was obtained in the region of 1000 Hz or higher.

(Example 20)
Under the conditions of Example 1, the size of the frame 14 was changed to 30 mm, the thickness of the film 18 was changed to 200 μm, and the other conditions were the same including the hole size to produce a soundproof structure sample. The measurement results of Example 20 thus obtained are shown in Table 4. Since the conditions of Example 20 are four times the thickness of the film 18 and twice the size of the frame 14 from the conditions of Example 14, the first vibration mode of the natural vibration is expected to be the same, and the measurement is performed. Was actually the same frequency.

(Example 21)
In Example 20, a soundproof structure sample was manufactured under the same conditions except that the film thickness was changed to 800 μm instead of 200 μm. The measurement results of Example 21 thus obtained are shown in Table 4. In Example 21, the film thickness was 16 times and the frame size was 4 times that in Example 1, and the first vibration mode of natural vibration was expected to be the same. When measured, a transmission peak (minimum) actually appeared at the same frequency of 2820 Hz. The transmission loss peak (maximum) showed a large peak at 708 Hz. This transmission loss spectrum is shown in FIG.

(Example 22)
A soundproof structure sample was prepared in the same manner as in Example 21 except that the hole diameter was changed from 200 μm to 1600 μm. The measurement results of Example 22 thus obtained are shown in Table 4.
Even when the size of the frame 14 was large, 2000 Hz or more could be shielded.

(Example 23)
In Example 1, instead of making a single through hole in the center, four holes with a hole diameter of 200 μm were made in the center. Others produced a soundproof structure sample under the same conditions as in Example 1. The measurement results of Example 23 obtained in this way are shown in Table 4. The transmission loss spectra of Example 23 and Example 5 are shown in FIG. The shielding frequency was 2000 Hz in agreement with the single hole having a hole diameter of 400 μm in Example 5. That is, when the through holes 22 on the film 18 in the frame 14 have the same aperture ratio without changing other conditions, the shielding spectra in the case of the single hole 22 and the plurality of holes 22 almost coincided.

(Examples 24 to 30)
In Example 1, instead of making a single through hole in the center, the position where the hole 22 having a hole diameter of 200 μm was made a position shifted on the diagonal line in the square frame. Others produced a soundproof structure sample under the same conditions as in Example 1. Table 4 shows the measurement results of each example thus obtained. The shielding frequency is not different from that in Example 1 with the hole 22 in the center, and this soundproofing system reveals that it is very robust with respect to the position of the hole 22 on the membrane 18.

(Example 31)
In Example 1, instead of making a single through hole, three holes having a hole diameter of 200 μm and four holes having a hole diameter of 100 μm were formed in the same soundproof cell 26. Others produced a soundproof structure sample under the same conditions as in Example 1. Table 5 shows the measurement results of Example 31 thus obtained. The shielding frequency is 2000 Hz, which is the same shielding frequency as in the case of the single hole having a hole total of 400 μm in Example 5. The total hole area in the cell in Example 5 and this example is the same.

(Example 32)
In Example 1, instead of using aluminum as a frame material, acrylic processed into a frame shape was used. Others produced a soundproof structure sample under the same conditions as in Example 1. The measurement results of Example 32 thus obtained are shown in Table 5. The same effect was obtained even if the material of the frame 14 was changed.

(Example 33)
In Example 1, a polyimide film was used in place of the PET film as the film material.
Others produced a soundproof structure sample under the same conditions as in Example 1. The measurement results of Example 33 obtained in this way are shown in Table 5. As in the case of the PET film, the polyimide film has a soundproof structure including the frame 14, the film 18, and the holes 22, and the transmission loss has a large peak.
(Example 34)
In Example 1, instead of the aluminum frame processed into the frame shape of the square through hole 12, an aluminum frame processed into the frame shape of the circular through hole 12 was used. Others produced a soundproof structure sample under the same conditions as in Example 1. The measurement results of Example 34 thus obtained are shown in Table 5.

(Example 35)
In Example 1, the shape of the black ink drawn on the PET film was made to be a square.
At this time, the length of one side was set to 200 [(√π) / 2] (μm) so that the area of the hole 22 would be the same as in Example 1 (the circular equivalent diameter is defined as the diameter of a circle of the same area) ). At this time, the ink jet method was used for drawing. Irradiation was performed so that the laser diameter was reduced to about 20 μm and black spots were scanned. Square holes 22 could be obtained by adjusting the laser power. The measurement results of Example 35 obtained in this way are shown in Table 5. As for the shielding frequency, the same result as in Example 1 was obtained. This indicates that the shielding characteristic does not depend on the shape of the hole 22 in the same area.

(Example 36)
In Example 35, a rectangular black ink shape was used instead of the square black shape. The long side was 200√π (μm) and the short side was 200 [(√π) / 4] (μm) so as to have the same area. A rectangular hole was obtained in the same manner as in Example 35. The measurement results of Example 36 thus obtained are shown in Table 5.
(Example 37)
In Example 1, a soundproof structure sample was prepared in the same manner as in Example 1 except that an aluminum foil thickness of 20 μm was used as the film 18 instead of the PET film. The measurement results of Example 37 thus obtained are shown in Table 5. The through hole 22 was formed by a needle. At this time, both the film 18 and the frame 14 are made of aluminum and are made of the same material. Since aluminum has a larger Young's modulus / density than a general polymer film material, a peak appears on the high frequency side even if it is thinner than a PET film.

(Example 38)
In Example 1, instead of processing the same hole diameter in all the cells, a soundproof structure sample including soundproof cells 26 having holes 22 having a diameter of 200 μm and holes 22 having a diameter of 100 μm so as to be staggered was produced. The measurement results of Example 38 obtained in this way are shown in Table 5. Moreover, the transmission loss spectrum of Example 38 is shown in FIG. At this time, the maximum (peak) frequency of shielding was 1258 Hz. According to Example 1 and Example 4, since the shielding frequency of the single soundproof cell 26 having the respective holes 22 was 1412 Hz and 1000 Hz, shielding could be realized at a frequency intermediate between them.

(Examples 39 to 41)
In Example 34, the diameter of the circular through-hole 12 of the frame 14 was changed from 7.5 mm to 4 mm, 2 mm, and 2 mm, respectively, and the diameter of the circular hole 22 was changed from 200 mm to 40 mm only in Example 41. In the same manner as in Example 34, a soundproof structure sample of each example was produced.
Table 5 shows the measurement results of the examples thus obtained. It can be seen that the first natural vibration frequency and the shielding frequency are both greatly shifted to the high frequency side by reducing the size of the frame.
(Example 42)
As the acoustic tube, an acoustic tube having an inner side length of 15 mm was prepared. Instead of using the 15 × 15 frame 14 in Example 18 to prepare a soundproof structure sample, a single 15 mm frame 14 made of aluminum (Al) was prepared, and the other was the same as in Example 18, A 200 μm thick PET film as the film 18 was passed through a 200 μm diameter circular hole as a hole 22 to prepare a sample. At this time, since the acoustic tube and the sample frame 14 are exactly the same size, the acoustic tube is used for a soundproof structure consisting of only one cell structure by matching the sample frame 14 with the sample holder of the acoustic tube. The measurement was performed so that it could be measured.
The results are shown in Table 5. The result was the same as the measurement result of Example 18.

As is apparent from Tables 3 to 5, the soundproof structures of Examples 1 to 42 of the present invention differ from Comparative Examples 1 and 2 in that the transmission is performed at the shielding peak frequency on the lower frequency side than the first natural vibration frequency. Since there is a shielding peak at which the loss becomes a peak, it is possible to selectively isolate a frequency band having a certain width around the shielding peak frequency.
Further, as is clear from FIG. 16, in the reference soundproof structure sample in the absence of the hole 22 in the middle of preparation of the soundproof structure sample of Example 16, the sound caused by the large vibration of the membrane at the first natural vibration frequency of the system Only the absorption peak was large. On the other hand, as is clear from FIG. 15, in the soundproof structure sample of Example 16, the hole 22 was drilled, so that the absorption rate on the lower frequency side was increased overall, and the absorption performance was improved. I understand. It was found that, in the soundproof structure sample of Example 16, greater absorption occurred on the low frequency side than the shielding peak caused by the hole 22 in particular.
From the above, it can be seen that the soundproof structure of the present invention has an excellent sound insulation characteristic that can shield a specific frequency component aimed at extremely strongly, and can further increase the absorption of the component on the lower frequency side. It was.

As mentioned above, although the various embodiment and the Example about the manufacturing method of the soundproof structure of this invention and the manufacturing method of a soundproof structure were mentioned and demonstrated in detail, this invention is not limited to these embodiment and an Example. Of course, various improvements or changes may be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 10 Soundproof structure 12 Through-hole 14 Frame 15 Plate-like member 16 Frame 18 Film 20 Film body 22 Hole (through-hole)
24 opening 26 soundproof cell

Claims

A soundproof structure having one or more soundproof cells,
Each of the one or more soundproof cells is
A frame having a through hole;
A membrane fixed to the frame;
An opening made of one or more holes perforated in the membrane,
Both ends of the through hole of the frame are not closed together,
The soundproof structure is defined by the opening of the one or more soundproofing cells on the lower frequency side than the first natural vibration frequency of the film of the one or more soundproofing cells and has a maximum transmission loss. A soundproof structure having a peak frequency and selectively soundproofing a certain frequency band centered on the shielded peak frequency.
The soundproof structure according to claim 1, wherein the one or more soundproof cells are a plurality of soundproof cells arranged two-dimensionally.
The first natural vibration frequency is determined by the geometric shape of the frame of the one or more soundproof cells and the rigidity of the membrane of the one or more soundproof cells,
The soundproof structure according to claim 1 or 2, wherein the shield peak frequency is determined according to an area of the opening of the one or more soundproof cells.
The first natural vibration frequency is determined by the shape and size of the frame of the one or more soundproof cells, and the thickness and flexibility of the film of the one or more soundproof cells,
The soundproof structure according to any one of claims 1 to 3, wherein the shielding peak frequency is determined according to an average area ratio of the openings of the one or more soundproof cells.
The soundproof structure according to any one of claims 1 to 4, wherein the first natural vibration frequency is included in a range of 10 Hz to 100,000 Hz.
When the equivalent circle radius of the frame is R1 (mm), the thickness of the film is t1 (μm), the Young's modulus of the film is E1 (GPa), and the equivalent circle radius of the opening is r (μm), The soundproof structure according to any one of claims 1 to 5, wherein the parameter A represented by the formula (1) is not less than 0.07000 and not more than 759.1.
A = √ (E1) * (t1 1.2 ) * (ln (r) −e) / (R1 2.8 ) (1)
Here, e indicates the number of Napiers, and ln (x) is the logarithm of x with e as the base.
When the equivalent circle radius of the frame is R2 (m), the thickness of the film is t2 (m), the Young's modulus of the film is E2 (Pa), and the density of the film is d (kg / m 3 ), The soundproof structure according to any one of claims 1 to 6, wherein the parameter B represented by the formula (2) is 15.47 or more and 235000 or less.
B = t2 / R2 2 * √ (E2 / d) (2)
The soundproof structure according to any one of claims 1 to 7, wherein the opening of the one or more soundproof cells is configured by a single hole.
The soundproof structure according to any one of claims 1 to 7, wherein the opening of the one or more soundproof cells is composed of a plurality of holes of the same size.
When the one or more soundproof cells are a plurality of soundproof cells arranged two-dimensionally,
The soundproof structure according to any one of claims 1 to 9, wherein 70% or more of the openings of the plurality of soundproof cells are configured by holes of the same size.
The soundproof structure according to any one of claims 1 to 10, wherein a size of the one or more holes in the opening of the one or more soundproof cells is 2 µm or more.
The soundproof structure according to any one of claims 1 to 11, wherein a size of the frame of the one or more soundproof cells is equal to or smaller than a wavelength size corresponding to the shielding peak frequency.
The soundproof structure according to any one of claims 1 to 12, wherein the one or more holes in the opening of the one or more soundproof cells are holes formed by a processing method that absorbs energy.
The soundproof structure according to claim 13, wherein the processing method for absorbing energy is laser processing.
The soundproof structure according to any one of claims 1 to 12, wherein the one or more holes in the opening of the one or more soundproof cells are holes formed by a machining method using physical contact.
The soundproof structure according to claim 15, wherein the machining method is punching or needle processing.
The soundproof structure according to any one of claims 1 to 16, wherein the membrane is impermeable to air.
The soundproof structure according to any one of claims 1 to 17, wherein one hole of the opening of the soundproof cell is provided at a center of the film.
The soundproof structure according to any one of claims 1 to 18, wherein the film is made of a flexible elastic material.
When the one or more soundproof cells are a plurality of soundproof cells arranged two-dimensionally,
The soundproof structure according to any one of claims 1 to 19, wherein the plurality of frames of the plurality of soundproof cells are configured as one frame body arranged so as to be two-dimensionally connected.
When the one or more soundproof cells are a plurality of soundproof cells arranged two-dimensionally,
The soundproofing device according to any one of claims 1 to 20, wherein the plurality of films of the plurality of soundproofing cells are configured by a single sheet-like film body covering the plurality of frames of the plurality of soundproofing cells. Construction.
In producing the soundproof structure according to any one of claims 1 to 21,
The one or more holes in the opening of the one or more soundproofing cells are perforated in the film of each soundproofing cell by a processing method for absorbing energy or a mechanical processing method by physical contact. Structure manufacturing method.
The processing method for absorbing the energy is laser processing,
The method for manufacturing a soundproof structure according to claim 22, wherein the machining method is punching or needle processing.