JP7033055B2 - Soundproof structure and soundproof panel - Google Patents

Description

The present invention relates to a soundproof structure and a soundproof panel, and in particular, a core body constituting a plurality of cells is arranged between a back plate and a perforated plate, and a flow resistor is superposed on the perforated plate on the opposite side of the core body. The present invention relates to a soundproof structure composed of the above and a soundproof panel using the same.

The soundproof structure and the soundproof panel using the soundproof structure are required to be improved in quality from various viewpoints such as weight, rigidity, and strength.

Specifically, a lighter soundproof panel is desirable from the viewpoint of portability and safety in the event of a fall. Further, assuming that it is used as a simple wall or partition, a highly rigid soundproof panel that suppresses changes in acoustic performance and whose shape does not easily change is required. Further, from the viewpoint of fragility, a soundproof panel having higher strength is desirable.

By the way, for the soundproof structure, a sound absorbing material made of a porous material such as urethane foam and felt is often used. However, since the porous material is soft, it has no rigidity, and it is difficult to secure the strength. On the other hand, a sound absorbing material made of a metal material, ceramics, or the like may be used. Among them, there is a sound absorbing material which is a foam material and has high rigidity, but even such a sound absorbing material has a large weight and it is difficult to secure the strength.

Based on the above circumstances, soundproof structures with various structures have been developed so far. As an example thereof, as described in Patent Documents 1 and 2, a core body constituting a plurality of cells is arranged between a back surface plate and a perforated plate, and a flow resistor is placed on the opposite side of the core body. Examples thereof include a soundproof structure and a soundproof panel configured to be stacked on top of each other.

Specifically, in the soundproof panel described in Patent Document 1, the honeycomb core material layer is sandwiched between the perforated metal plate and the backing plate, and the perforated metal plate is covered with a metal cloth sheet such as wire woven fabric or metal felt. It is composed of. Further, the above-mentioned metal cloth sheet has a flow resistance of 5 to 300 Pa · s / m (= Rayls).

Further, in the soundproof panel described in Patent Document 2 (denoted as "acoustic plate" in Patent Document 2), an upper layer composed of a woven fabric having high sensitivity to the speed of sound and a support sheet having a certain porosity. Is combined with a conventional intermediate honeycomb layer and lower layer. Also, the woven fabrics that make up the top layer have a given nominal resistance to the speed of sound and known resistance fluctuations.

With the structures described in Patent Documents 1 and 2, it is possible to realize a soundproof structure having high sound absorption, wide band sound absorption characteristics, and high rigidity.

Japanese Unexamined Patent Publication No. 2002-189475 Japanese Unexamined Patent Publication No. 2002-258869

However, in the soundproof panel described in Patent Document 1, as described above, a metal cloth sheet of 0 to 300 Pa · s / m is used as a flow resistor. Further, according to Patent Document 1, it is desirable that the resistance value of the metal cloth sheet is a relatively low acoustic resistance, for example, about 10 Rayls at 20 cm / sec (see paragraph 0016 of Patent Document 1). However, in a soundproof panel using a flow resistor having extremely low flow resistance, a desired sound absorption effect cannot be obtained for a sound appearing on a relatively low frequency side such as a human voice. Such a problem can also occur in the soundproof panel described in Patent Document 2.

The soundproof panels of Patent Document 1 and Patent Document 2 both reduce relatively high frequency (specifically, for example, 10000 Hz or more) sound such as noise generated from a jet engine of an aircraft or the like. In the first place, it is not intended for relatively low frequency sounds such as human voice.

On the other hand, soundproof structures and soundproof panels attached to buildings and rooms in buildings are often used for purposes such as suppressing human conversation and making it difficult for others to hear, and the demand for them has increased in recent years. There is. Therefore, as the quality of the soundproof structure and the soundproof panel, it is required to absorb relatively low frequency sound such as human voice in a wide band. Further, since the soundproof structure and the soundproof panel may be used by arranging them on a wall surface or a ceiling, it is required that the soundproof structure and the soundproof panel be as small as possible, particularly thin.

Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to solve the following object.
Specifically, the present invention solves the above-mentioned problems of the prior art, and provides a soundproof structure and a soundproof panel having a relatively small structure and capable of absorbing relatively low frequency sound in a wide band. The purpose is to provide.

As described above, the soundproof structure in which the core body constituting a plurality of cells is arranged between the back plate and the perforated plate and the flow resistor is superposed on the perforated plate on the opposite side of the core body is compared. It has a compact structure and is lightweight, yet has high rigidity and high strength.
As a result of diligent studies to solve the above problems, the present inventors have obtained sound absorption in a wide band when the flow resistance of the flow resistor is 350 Pa · s / m to 1500 Pa · s / m. The present invention has been completed by finding that the sound absorption peak frequency at which the sound absorption coefficient is maximized shifts to the low frequency side.
That is, the present inventors have found that the above problem can be solved by the following configuration.

[1] Each of the core body constituting the plurality of cells, the back plate covering the opening surface of each of the plurality of cells in the thickness direction of the core body, and the plurality of cells at positions opposite to the back plate in the thickness direction. A perforated plate that covers the opening surface and has through holes, and a flow resistor that is overlapped with the perforated plate at a position opposite to the core body in the thickness direction and has air permeability. A soundproof structure having a flow resistance of 350 Pa · s / m or more and 1500 Pa · s / m or less.

[2] The soundproof structure according to [1], wherein the surface density of the flow resistor is 60 g / m ² or more and 500 g / m ² or less.
[3] The soundproof structure according to [1] or [2], wherein the flow resistor is made of a fine through-hole plate or a porous sound absorbing material.
[4] The soundproof structure according to any one of [1] to [3], wherein the flow resistor is made of cloth.
[5] The soundproof structure according to any one of [1] to [4], wherein the thickness of the flow resistor is less than 1 mm.
[6] The soundproof structure according to any one of [1] to [5], which is a honeycomb core.
[7] The soundproof structure according to any one of [1] to [6], wherein at least one of the core body, the back plate and the perforated plate is made of a material in which voids are distributed inside.
[8] The soundproof structure according to [7], wherein the core body, the back plate, and the perforated plate are all made of a material in which voids are distributed inside.
[9] The soundproof structure according to [8], wherein the core body, the back plate, and the perforated plate are all made of paper material.
[10] The flow resistor has a processed portion that has been processed to modify the properties of the flow resistor, and the flow resistance of the processed portion after processing is 350 Pa · s / m or more and 1500 Pa. -The soundproof structure according to any one of [1] to [9], which is s / m or less.
[11] A soundproof panel configured by the soundproof structure according to any one of [1] to [10].

According to the present invention, a soundproof structure and a soundproof panel capable of absorbing sound of a relatively low frequency in a wide band with a relatively small structure are realized.

It is a partial cross-sectional view which shows the soundproof structure which concerns on one Embodiment of this invention. FIG. 1 is a top view schematically showing the soundproof structure shown in FIG. 1 by partially breaking it. It is a top view which shows the modification of the structure of a core body. It is a perspective view which shows the soundproof panel which concerns on one Embodiment of this invention. It is a figure which shows the sound absorption coefficient of the soundproof structure produced in Example 1. It is a figure which shows the calculation result when the sound absorption coefficient of the soundproof structure produced in Example 1 was calculated by each of the Ridid model Biot model. It is a figure which shows the calculation result about the sound absorption coefficient of the soundproof structure using the sound absorbing material which has a flow resistance of 100 Pa · s / m. It is a figure which shows the calculation result of the sound absorption coefficient when the flow resistance is 100, 500, 800 and 3000 Pa · s / m. It is a figure which shows the maximum sound absorption coefficient for each flow resistance. It is a figure which shows the result of having evaluated the sound absorption peak width which satisfies the sound absorption coefficient 50% or more for each flow resistance. It is a figure which shows the sound absorption peak frequency specified for each flow resistance. It is a figure which shows the result of having differentiated the sound absorption peak frequency by the flow resistance. It is a figure which shows the evaluation result about the degree of low frequency of a sound absorption peak frequency. It is a figure which shows the sound absorption peak frequency when the surface density and the flow resistance are changed respectively. It is a figure which shows the maximum sound absorption coefficient when the surface density and the flow resistance are changed respectively. It is a figure which shows the sound absorption peak width when the surface density and the flow resistance are changed respectively. It is a figure which shows the change of the sound absorption peak frequency when the surface density is changed. It is a figure which shows the change of the maximum sound absorption coefficient when the surface density is changed.

The soundproof structure and the soundproof panel of the present invention will be described in detail below based on the preferred embodiments shown in the accompanying drawings.
The description of the constituent elements described below may be based on a typical embodiment of the present invention, but the present invention is not limited to such an embodiment.

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

Further, "soundproofing" in the present invention is a concept including both meanings of "sound insulation" and "sound absorption". Here, "sound insulation" means "shielding sound", in other words, "not transmitting sound", and mainly reflects sound (acoustic). Further, "sound absorption" means "reducing reflected sound", and in an easy-to-understand manner, means absorbing sound (sound). Further, in the present invention, since the back plate described later is used, the transmitted sound is originally small, and the reflected sound becomes a problem. In such a system, it is appropriate to use an index evaluated from the viewpoint of "sound absorption" described above (that is, an index of low reflected sound). Therefore, in the following, "soundproofing" will be mainly referred to as "sound absorption", and "sound insulation" and "sound absorption" will be referred to to distinguish between the two.

<< Outline of the soundproof structure of the present invention >>
First, the outline of the soundproof structure of the present invention will be described.
The soundproof structure of the present invention includes a core body constituting a plurality of cells, a back plate covering the opening surface of each of the plurality of cells in the thickness direction of the core body (hereinafter referred to as the thickness direction), and a back plate in the thickness direction. It has a perforated plate that covers the opening surface of each of the plurality of cells at a position opposite to the core body, and a flow resistor superposed on the perforated plate at a position opposite to the core body in the thickness direction (for example). , See Figure 1).

The core body and the back plate form a resonance structure, or more strictly, an air column resonance structure. Through holes are formed in the perforated plate. The flow resistor has a large number of micropores formed therein, and therefore has air permeability. The flow resistance of the flow resistor is 350 Pa · s / m or more and 1500 Pa · s / m or less.

The soundproof structure of the present invention configured as described above is lightweight, yet highly rigid and high-strength, has a relatively small (compact) structure, and has a relatively low frequency such as a human voice. It becomes possible to absorb the sound of the above in a wide band (see, for example, FIG. 5).

More specifically, the soundproof structure of the present invention has both a sound absorbing effect due to the air column resonance structure composed of the core body and the back plate and a sound absorbing effect in the flow resistor. Here, the flow resistor is a cloth or the like having a relatively thin thickness, but has a characteristic of affecting the sound absorption performance of the soundproof structure. Among the characteristics of the flow resistor, the present inventors have discovered that the flow resistance has a great influence on the sound absorption characteristics (specifically, the range of frequencies capable of absorbing sound), and have found a suitable range thereof. Specifically, by increasing the flow resistance, the sound absorption peak frequency at which the sound absorption coefficient is maximized shifts to the low frequency side. As a result, a soundproof structure capable of absorbing relatively low-frequency sound over a wide band is realized while having a compact structure.

Explaining the influence of the flow resistance of the flow resistor on the sound absorption performance, the flow resistor in which the micropores are formed has air permeability because the micropores form a ventilation portion. Then, the flow resistor absorbs sound due to the friction generated when the sound passes through and exits the above-mentioned ventilation portion. In the following, the material portion of the flow resistor other than the micropores will be referred to as a “frame” for convenience.

By the way, a normal sound absorbing material is composed of a flow resistor having a relatively low flow resistivity, and in a soundproof structure using this, the resistance against the passage of sound through the above-mentioned ventilation portion (in other words, micropores) is compared. Small. Therefore, the incident sound mainly passes through the ventilation portion, and the thermally viscous friction generated at that time contributes to the sound absorption. On the other hand, as described above, since the sound easily flows through the ventilation portion, the frame does not almost shake, so that the frame itself does not contribute to the sound absorption characteristics.
In the above case, the sound absorption peak frequency at which the sound absorption coefficient is maximized is determined by the distance of the back surface portion of the flow resistor (specifically, the air layer on the back surface side of the flow resistor in the sound incident direction). Specifically, the sound absorption peak frequency is extremely close to the frequency of air column resonance determined by the thickness of the air layer on the back surface side, assuming that there is no flow resistor.
Therefore, in a soundproof structure using a normal sound absorbing material, it is difficult to make the sound absorbing frequency significantly lower than the air column resonance frequency determined from the size of the structure.

On the other hand, as described above, by increasing the flow resistance of the sound absorbing material (flow resistor), the sound absorbing peak frequency is shifted to the low frequency side. Explaining this from the viewpoint of the microscopic sound absorption mechanism, the larger the flow resistance, the more the effect that the frame is shaken by the sound as well as the friction when the sound passes through the micropores in the flow resistance body is added. Become.

More specifically, as the flow resistance (that is, the ventilation resistance in the micropores) becomes large, the resistance to the passage of the sound of the ventilation portion is large, and the sound does not easily flow to the ventilation portion. As a result, instead of passing a part of the incident sound (sound to be absorbed) through the ventilation portion, the frame is shaken. As a result, it is considered that the vibration and mass of the frame in the flow resistor contribute to the sound absorption effect.

Then, the vibration and mass of the frame contribute to sound absorption, so that the sound absorption peak frequency shifts to the low frequency side. In particular, in the soundproof structure of the present invention, as described above, a flow resistance body having a flow resistance of 350 to 1500 Pa · s / m is used. As a result, the sound absorption peak frequency is 10% or more of the resonance frequency of the air column resonance generated in the core body (specifically, in each opening of a plurality of cells) in the sound absorption structure without the flow resistor. It can be shifted to the low frequency side (see, for example, FIG. 13).

The above-mentioned effect of lowering the sound absorption peak frequency can be explained as an effect due to the mass of the frame. Specifically, in a flow resistor body to which the vibration of the frame does not contribute, only the friction of the ventilation part (strictly speaking, the thermal viscous friction of the air in the ventilation part) contributes to the sound absorption, so that the mass of the frame (strictly speaking) , Density) does not affect the sound absorption peak frequency. On the other hand, in a situation where the frame is shaken, the mass of the frame affects the sound absorption. Here, the mass component of the frame is a quantity that follows the equation of motion, and has the effect of increasing the inductance in the acoustic equivalent circuit theory. Then, as the inductance increases, the resonance frequency of the equivalent circuit shifts to the low frequency side. According to this theory, it is considered that the mass of the frame gives the effect of lowering the sound absorption peak frequency.

The above effect is difficult to obtain when a flow resistor having a low resistance (specifically, 10 to 300 Pa · s / m) is used as in the soundproof panels described in Patent Documents 1 and 2. In the first place, since the soundproof panel described in Patent Documents 1 and 2 targets relatively high frequency sound of 10,000 Hz or higher such as noise derived from a jet engine, it is not necessary to lower the frequency of the sound to be absorbed. Therefore, the soundproof panels described in Patent Documents 1 and 2 cannot sufficiently absorb noise having a lower frequency than the noise derived from a jet engine, such as a human voice. On the other hand, the soundproof structure of the present invention can absorb relatively low frequency sound due to the above-mentioned low frequency effect of the sound absorption peak frequency.

Here, a resonator is mentioned as a typical sound absorbing structure, the soundproof structure of the present invention is compared with the resonator, and the superiority of the soundproof structure of the present invention will be described. Examples of the resonator include an air column resonator in which the sound absorption peak frequency is determined only by the distance of the air column (columnar air portion). On the other hand, as another resonator, a membrane is arranged on the opening surface of the tubular body, and the sound absorption peak frequency is determined based on the mass (mass) of the membrane and the distance between the back space (back distance). The body is mentioned. The "membrane-type resonator" referred to here is not due to mass spring resonance due to the membrane vibration mode of the membrane, but when the membrane is used as the mass, that is, the one in which only the mass of the membrane and the back space contribute to sound absorption. Point to.

When the speed of sound is c, the back distance is d, the surface density of the film is m, and the density of air is rho, the resonance frequency fs1 in the air column resonator and the resonance frequency in the membrane type resonator due to mass. fs2 is determined by the following equations (1) and (2), respectively.
fs1 = c / (d × 4) (1)
fs2 = c / {2π × √ (rho / m / d)} (2)
Here, the density rho of air at 20 ° C. and 1 atm is 1.205 kg / m ³ , and at this time, the resonance frequency fs2 is expressed by the following equation (3).
fs2 = 60 / √ (m × d) (3)

In the case of a membrane-type resonator, as is clear from the above equations (2) and (3), the back surface distance d and the weight of the membrane (strictly speaking, the surface density m) contribute to the sound absorption peak frequency. Further, although it depends on the back surface distance d, when the back surface distance d is several cm and the surface density m of the membrane is approximately 0.03 kg / m ² or more, the resonance frequency fs1 of the air column resonator is used. The resonance frequency fs2 of the membrane-type resonator is sufficiently lower.

In the above-mentioned two types of resonators, due to the nature of the resonator, the range in which the desired sound absorption coefficient can be obtained (hereinafter referred to as the sound absorption peak width) is narrowed around the sound absorption peak frequency. That is, it is difficult for the above-mentioned resonator to absorb the target sound in a wide band.

On the other hand, in the soundproof structure of the present invention, the sound absorption peak width can be widened by using the flow resistor. Further, when the flow resistor has a relatively high flow resistance, the sound absorption effect in a wide band due to the provision of the ventilation portion composed of micropores and the sound absorption peak frequency due to the mass of the frame move to the lower frequency side. It is possible to realize the shift effect of.

More specifically, in the present invention, as described above, a flow resistance body having a flow resistance of 350 to 1500 Pa · s / m is used. As a result, the sound absorption coefficient at the sound absorption peak frequency is 98% (17 dB when converted to mute volume), and the sound absorption peak width set to the sound absorption rate of 50% or more (3 dB or more when converted to mute volume) is 3500 Hz. (See, for example, FIGS. 9 and 10).
By the way, the muffling volume (unit is dB) is a value evaluated by the reduction ratio of the reflected sound with respect to the incident sound. Specifically, when the incident volume energy is Iinc and the reflected volume energy is Iref, it is reflected. The rate will be Reflect / Iinc. At this time, the mute volume (unit: dB) can be calculated as 10 × log10 (Iinc / Iref).

The sound absorption peak frequency of the soundproof structure of the present invention exists between the resonance frequency fs1 of the air column resonator and the resonance frequency fs2 of the membrane-type resonator. Specifically, the sound absorption peak frequency is close to the resonance frequency fs1 of the air column resonator when the sound flows only through the ventilation portion of the flow resistor and hardly shakes the frame, and the contribution of the vibration of the frame is large. Approaches the resonance frequency fs2 of the membrane-type resonator. On the other hand, as described above, when the flow resistor has a relatively low flow resistance as in Patent Documents 1 and 2, the sound absorption peak frequency becomes the resonance frequency fs1 described above. On the other hand, when the contribution of the frame vibration becomes large, the resonance frequency fs2 is approached, so that the sound absorption peak frequency becomes low.

As described above, the soundproof structure of the present invention can effectively absorb relatively low-frequency sound in a wide band. Therefore, the soundproof structure of the present invention can be used for various purposes such as suppressing a person's conversation and making it difficult to hear around the room. For example, a house, a hall, an elevator, a classroom, an office, a conference room, etc. , Schools, nurseries and kindergartens, other buildings (specifically, factories and animal sheds, etc.), and various sound environments such as structures other than buildings.

Further, the soundproof structure of the present invention can of course be used for applications other than the above, and can be used, for example, as a material for distribution such as an interior material of an automobile, a box material, and a packing material. Further, the soundproof structure of the present invention can be used as a material for copiers, blowers, air conditioners, ventilation fans, pumps, generators, ducts and the like. Further, the soundproof structure of the present invention comprises various types of industrial equipment that emits sound such as coating machines, rotating machines, and conveyors; vehicles such as automobiles and trains, and transportation equipment such as aircraft; It can be used for general household equipment such as refrigerators, washing machines, dryers, televisions, copiers, microwave ovens, game machines, air conditioners, electric fans, personal computers, vacuum cleaners, air purifiers, and ventilation fans.
The soundproof structure of the present invention is appropriately arranged at a position where the sound generated from the noise source passes in the above-mentioned various uses.

<< Configuration example of the soundproof structure of the present invention >>
Next, a configuration example of the soundproof structure of the present invention will be described in detail with reference to FIGS. 1 and 2. FIG. 1 is a partial cross-sectional view showing a soundproof structure (hereinafter, soundproof structure 10) according to an embodiment of the present invention. Note that FIG. 1 also shows an enlarged view of a part of the flow resistor. FIG. 2 is a top view schematically showing the soundproof structure 10 with the soundproof structure 10 partially broken.

In addition, in FIG. 1, the thickness direction of the soundproof structure 10 is shown by an arrow. Here, the thickness direction of the soundproof structure 10 coincides with the thickness direction of the core body 12, and in the following description, the thickness directions of both are collectively referred to as the “thickness direction”.

Further, in FIG. 2, in order to make it easier to understand the structure of the soundproof structure 10, the portion of the soundproof structure 10 from which the perforated plate 20 and the flow resistor 24, which will be described later, are removed is placed on the left side of FIG. 2 and the flow resistance. The part where only the body 24 is removed is shown in the central part of FIG. 2, respectively.

As shown in FIGS. 1 and 2, the soundproof structure 10 is configured by stacking a flow resistance body 24, a perforated plate 20, a core body 12, and a back plate 18 from the side closer to the sound source in the thickness direction. Has been done.

As shown in FIG. 2, the core body 12 is a member constituting a plurality of cells 14. Each cell 14 is a frame having a tubular opening 14a along the thickness direction and a partition wall 14b surrounding the opening. Further, both end faces of each of the plurality of cells 14 in the thickness direction are open faces.

As shown in FIG. 1, the back plate 18 is a plate that covers each opening surface (strictly speaking, the end surface on the back side) of the plurality of cells 14 in the thickness direction. In the configuration shown in FIG. 1, the back plate 18 is joined to one end surface of the core body 12 in the thickness direction, and closes the opening 14a of each cell 14.

As shown in FIG. 1, the perforated plate 20 covers the opening surface of each of the plurality of cells 14 on the side opposite to the back plate 18 (that is, the side closer to the sound source) in the thickness direction. In the configuration shown in FIG. 1, the perforated plate 20 is joined to the other end surface of the core body 12 in the thickness direction (the end surface opposite to the side to which the back plate 18 is joined). Further, as shown in FIG. 2, the perforated plate 20 has a through hole 22 formed at a position corresponding to each of the plurality of cells. Each through hole 22 is provided at a position communicating with the opening 14a of the cell 14.

The flow resistance body 24 is superposed on the perforated plate 20 at a position opposite to the core body 12 in the thickness direction. Further, the flow resistance body 24 has air permeability, and micropores 26 forming a ventilation portion are formed inside the flow resistance body 24. Further, the flow resistance body 24 is preferably made of a fine penetrating plate or a porous sound absorbing material, and particularly preferably made of cloth. Here, the cloth refers to a fiber aggregate including a non-woven fabric, a woven cloth, a knitted fabric, and the like. Further, the material of the cloth may be a natural yarn, a synthetic yarn, a metal material or the like.
On the other hand, the fine through-hole plate refers to a plate having a large number of through holes of about 1 mm or less, and may be a plate in which holes are chemically formed by etching or the like, or a plate in which through holes are physically formed. Alternatively, it may be a fine through-hole plate having a structure in which a through-hole-shaped portion is formed by a structural device. The fine through-hole plate includes punching metal and expanded metal.

Hereinafter, each component of the soundproof structure 10 will be described individually.
[Core body]
The core body 12 is sandwiched between the back plate 18 and the perforated plate 20 in the thickness direction. Each opening 14a of the plurality of cells 14 composed of the core body 12 is closed by the back plate 18 and the perforated plate 20. That is, on the back side of the through hole 22 of the perforated plate 20, the opening 14a of each cell 14 becomes a closed space to form a back space. Then, each cell 14 of the core body 12 and the back plate 18 cooperate to form an air column resonance structure.

Further, as shown in FIG. 1, a plurality of through holes 22 are formed in the perforated plate 20 so that one of the through holes 22 of the perforated plate 20 communicates with the opening 14a of one cell 14. It is preferable to have it. That is, it is desirable that the plurality of through holes 22 formed in the perforated plate 20 are arranged one-to-one with one of the openings 14a of the plurality of cells 14, respectively. In this case, if the openings 14a of the plurality of cells 14 are regularly arranged, the plurality of through holes 22 are also regularly arranged in the perforated plate 20 according to the regularity of the arrangement of the openings 14a. become.
Further, when each through hole 22 is arranged so that the plurality of through holes 22 correspond to one cell 14, the same effect as described above can be obtained. That is, for example, it is possible to periodically arrange each through hole 22 so that the opening 14a of one cell 14 and the three through holes 22 communicate with each other. However, considering the time and effort required to form the through hole 22 in the perforated plate 20, forming one large hole is more cost effective than forming a large number of holes, so that the cell 14 has one cell. It is desirable that one through hole 22 corresponds to it.
Further, the through holes 22 do not have to correspond one-to-one with all the cells 14, and if the number of through holes 22 corresponds with respect to a certain number of cells, the same effect as described above can be obtained. Specifically, either the length of the wavelength corresponding to the sound absorption peak frequency or, when the size of the soundproof structure 10 is smaller than the wavelength corresponding to the sound absorption peak frequency, the size of the entire soundproof structure 10 is all. If the number of through holes 22 corresponds to 50% or more of the cells, the same effect as described above can be obtained. It is preferable that the number of through holes 22 corresponds to the cell 14 which is preferably 70% or more, more preferably 90% or more. This is because, as a property of sound waves that are waves, the sound absorption performance from the structure of each cell 14 is not propagated as it is when the soundproof structure of the present invention is arranged, and it is about the wavelength size of the sound wave. This is because the effect of the averaged sound absorption performance appears.

The arrangement of the openings 14a of each cell 14 in the core body 12 and the positional relationship between the openings 14a of each cell 14 and the through holes 22 of the perforated plate 20 are not limited to the above contents. For example, two or more through holes 22 of the perforated plate 20 may be arranged so as to correspond to the opening 14a of one cell 14. Further, the openings 14a of each cell 14 may not be regularly arranged in the core body 12.

Further, from the viewpoint of ensuring the strength of the soundproof structure 10, the core body 12 is preferably a honeycomb core having a honeycomb structure. That is, the shape of the plurality of cells 14 is preferably a honeycomb (regular hexagon) shape in a plan view as shown in FIG. However, the structure of the core body 12 is not limited to the honeycomb structure, and the cell shape may be a substantially rectangular shape in a plan view as in grating, and the cell shape may be in a plan view as in expanded metal. It may have a substantially rhombic shape. Alternatively, as shown in FIG. 3, the structure of the core body 12 is such that a plurality of corrugated slate are arranged so that the front and back directions are alternately switched, and the cell shape is substantially spindle-shaped in a plan view. good. FIG. 3 is a top view showing a modified example of the structure of the core body 12.

The structure of the core body 12, that is, the shape of each cell 14 is not limited to the above contents, and includes special quadrangles such as circles, ellipses, parallelograms, trapezoids, triangles, pentagons, octagons, and the like. It may be polygonal or indefinite. Further, the shape of the cell 14 may be the same (constant) among all the cells 14, or may be different among the cells 14.

Incidentally, the size of the opening 14a of the cell 14 can be defined as the diameter or the length of the longest diagonal line in the regular polygon when the planar shape of the opening 14a is a regular polygon such as a circle or a square. can. Further, when the planar shape of the opening 14a is polygonal, elliptical or amorphous, it can be defined as a diameter equivalent to a circle. Here, the "circle-equivalent diameter" is the diameter when converted into circles having the same area.

Supplementing to the cell 14 of the core body 12, the size of the opening 14a of each cell 14 (that is, the diameter of the opening 14a, the length of the longest diagonal line, and the diameter corresponding to the circle) is perforated as shown in FIG. It is larger than the diameter of the through hole 22 of the plate 20. Incidentally, the size of the opening 14a 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 size of the opening 14a is preferably 1.0 mm to 500 mm is that when the size is smaller than 1.0 mm, the air viscous resistance in the inner wall surrounding the opening 14a is remarkably increased, so that the sound absorption effect is lowered. However, it becomes difficult to manufacture the core body 12. Further, when the size is larger than 500 mm, the rigidity of the core body 12 is remarkably lowered.

The size of the opening 14a of each cell 14 may be the same (constant) among all the cells 14, and the size of the opening 14a of some cells 14 may be the same (constant) among all the cells 14, and the size of the opening 14a of some cells 14 may be the same (constant) among the other cells 14. It may be different from the size of. The shape and size of the opening 14a (in other words, the shape and plane size of the cell 14) are not particularly limited, and depend on the plane shape and size (area) of the back plate 18 and the perforated plate 20. It may be set appropriately.

Further, the ratio (opening ratio) occupied by the opening 14a of the cell 14 on the end surface of the core body 12 in the thickness direction is larger than the opening ratio of the through hole 22 in the perforated plate 20.

The thickness of the core body 12 is equal to the distance between the back plate 18 and the perforated plate 20. The thickness of the core body 12 is not particularly limited and may be appropriately set according to the place and environment in which the soundproof structure 10 of the present invention is used, but is preferably 1.0 mm to 200 mm, for example. It is more preferably 5 mm to 100 mm, and particularly preferably 10 mm to 50 mm. Here, the reason why the thickness of the core body 12 is preferably 1.0 mm to 200 mm is that if it is less than 1.0 mm, the rigidity of the core body 12 is greatly reduced, and if it is more than 200 mm, the soundproof structure 10 is used. This is because there is a risk that the size will increase and it will not be possible to arrange it depending on the location.

The material of the core body 12 is not particularly limited as long as it is lightweight, has high rigidity, and exhibits a good function as the core body 12. That is, the core body 12 supports the perforated plate 20 and the flow resistance body 24, maintains a constant distance between the back plate 18 and the perforated plate 20, and has an air column resonance structure together with the back plate 18. The material of the core body 12 can be freely selected as long as it is constituent.

Explaining the material of the core body 12 in detail, the material of the core body 12 may be, for example, a flammable material. Here, the flammable material refers to a material other than the flame-retardant material described later, and examples thereof include a paper material, wood, and a resin material such as a synthetic resin. Examples of the paper material include Japanese paper, paper, and a corrugated cardboard structure using a pulp raw material, a honeycomb corrugated cardboard structure, a board, and the like. Examples of the resin material include PET (polyethylene terephthalate), TAC (triacetyl cellulose), PVDC (polyvinylidene chloride), PE (polyethylene), PVC (polyvinyl chloride), PMP (polymethylpentene), and COP (cycloolefin). Polymer), Zeonoa, Polycarbonate, PEN (Polyethylene Naphthalate), PP (Polypropylene), PS (Polypropylene), PAR (Polyalilate), Aramid, PPS (Polyphenylidene Sulfide), PES (Polyethersulfon), Nylon, PEs ( Polyester), COC (Cyclic Olefin Copolymer), Diacetyl Cellulose, Nitro Cellulose, Cellulose Derivatives, Polyamide, Polyamideimide, POM (Polyoxymethylene), PEI (Polyetherimide), PMMA (Polymethylmethacrylate), Polyrotaxane (Slide) (Ring material, etc.) and polyethylene, etc. can be mentioned. Further, a so-called corrugated plastic structure mainly using polypropylene or polycarbonate can also be used.

However, the material of the core body 12 is not limited to the above contents, and may be, for example, a flame-retardant material. Here, the flame-retardant material is a non-combustible material specified in Article 2, Item 9 of the Building Standards Act, and a quasi-flame-retardant material specified in Article 1, Item 5 of the Building Standards Act Enforcement Ordinance when it is used as a building material. Refers to non-combustible materials and flame-retardant materials specified in Article 1, Item 6 of the Enforcement Ordinance. 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 protection, 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 fiber plates, and flame-retardant plastic plates. Examples of the metal material include aluminum, steel, titanium, magnesium, tungsten, iron, steel, chromium, chromium molybdenum, nichrome 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 core body 12 other than the above, a material containing carbon fiber such as carbon fiber reinforced plastics (CFRP), carbon fiber, and glass fiber reinforced plastics (GFRP) can be mentioned. Be done.
The core body 12 may be formed by combining a plurality of types of the materials mentioned above.

Incidentally, among the materials of the core body 12 described above, the paper material, the metal material and the resin material are preferable, and the paper material is more preferable in that it is lighter and can be easily incinerated. Further, if the paper material is coated with an aramid resin, fire resistance is imparted, which is further preferable.

The thickness (plate thickness) of the material itself of the core body 12 is not particularly limited, but is preferably 0.001 mm (1 μm) to 5 mm, preferably 0.01 mm (10 μm) to 2 mm, for example. Is more preferable, and 0.1 mm (100 μm) to 1.0 mm is particularly preferable. Here, the reason why the plate thickness of the material of the core body 12 is preferably 0.001 mm (1 μm) to 5 mm is that if it is less than 0.001 mm (1 μm), the rigidity of the core body 12 cannot be sufficiently secured. .. Further, when it exceeds 5 mm, the core body 12 becomes remarkably heavy, which hinders the weight reduction of the core body 12.

Further, among the plurality of cells 14 formed by the core body 12, sound absorbing material made of a porous sound absorbing material, for example, a fiber such as a woven fabric, a knitted fabric, a non-woven fabric, or felt, is contained in the opening 14a of at least a part of the cells 14. A material or a foam material such as porous urethane may be arranged. Further, a sound absorbing material may be interposed between the core body 12 and the perforated plate 20.

Further, it is preferable that the core body 12 is fixed to each of the back plate 18 and the perforated plate 20 without any gap. As for the method of fixing each of the back plate 18 and the perforated plate 20 to the core body 12, any method may be used as long as the fixed state can be well maintained, and the method is not particularly limited. Examples of the fixing method include a method using an adhesive, a method using a physical fixative, and the like.

Explaining the fixing method using an adhesive, the adhesive is applied to both end faces of the core body 12 in the thickness direction (in other words, the opening faces of each of the plurality of cells 14), and the back plate 18 is placed on one end face. , The perforated plate 20 is placed on the other end face, and each is fixed to the core body 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.

Explaining the method of using a physical fixing tool, the back plate 18 and the perforated plate 20 arranged so as to sandwich the core body 12 in the thickness direction are provided with a fixing member such as a rod and the core body 12 (not shown). Examples thereof include a method of sandwiching the fixing member between the two and fixing the fixing member to the core body 12 with a fixing tool (fastener) such as a screw and a screw.

[Back plate]
The back plate 18 is a plate material that closes the opening surface of each of the plurality of cells 14 formed by the core body 12 on the back side (that is, the side opposite to the side on which the perforated plate 20 is provided). That is, as shown in FIG. 1, the back plate 18 covers the surface of the core body 12 on the back surface side and is arranged at a distance from the perforated plate 20 in the thickness direction.

The thickness of the back plate 18 is not particularly limited, but is preferably 0.001 mm (1 μm) to 5 mm, more preferably 0.01 mm (10 μm) to 2 mm, and 0.1 mm, for example. It is particularly preferably (100 μm) to 1.0 mm.

Further, the planar shape and size (area) of the back plate 18 are not particularly limited as long as they can cover the surface of the core body 12 on the back surface side, and other members (core body 12, It may be appropriately set according to the planar shape and size of the perforated plate 20 and the flow resistor 24).

Further, the material of the back plate 18 is not particularly limited, and the same material as the material of the core body 12 described above can be used. Specifically, examples of the material of the back plate 18 include paper materials, various metals such as aluminum and iron, and various resin materials such as polyethylene terephthalate (PET) and polypropylene (PP).

The back plate 18 may cover the opening surface of each of the plurality of cells 14 formed by the core body 12, and for example, the back plate 18 may cover the housing or cover of the device in which the soundproof structure 10 is installed. May be used as. Alternatively, the wall of the room or the like may be used as the back plate 18. That is, for example, when a structure composed of a flow resistor 24, a perforated plate 20, and a core body 12 is installed on a wall, the above structure is placed so that the surface on the back surface side of the core body 12 abuts on the wall. By arranging them, the wall may be configured to function as the back plate 18.

[Perforated plate]
The perforated plate 20 is made of a plate material having a slight thickness, and has a plurality of through holes 22 to penetrate. The plurality of through holes 22 are covered with the flow resistor 24 arranged on the perforated plate 20 and become invisible. Such an aspect is preferable in terms of the appearance (design) of the soundproof structure 10.

As described above, the position of forming the through hole 22 in the perforated plate 20 is set so as to correspond to the opening 14a of the cell 14 of the core body 12. Specifically, the through hole 22 is formed so that the flow resistance body 24, the through hole 22, and the opening 14a of the cell 14 communicate with each other, whereby the sound absorbing effect is exhibited. More specifically, on the back surface side of each through hole 22, a closed space (air layer) surrounded by the partition wall 14b of each cell 14 of the core body 12 and the back plate 18 is formed. In this closed space, air column resonance occurs at a frequency corresponding to the length (backward distance) of the closed space. That is, each cell 14 having the opening 14a and the back plate 18 that closes the opening surface on the back side of each cell 14 form an air column resonance structure. Further, the through hole 22 of the perforated plate 20 communicating with the closed space is formed large enough not to interfere with the air column resonance. Strictly speaking, the through hole 22 is formed under the condition that the induction of Helmholtz resonance is small due to the expansion and compression of the diameter of the through hole 22 and the volume of the closed space, and the air column resonance due to the back surface distance is predominant.

The through holes 22 may be arranged regularly or randomly in the perforated plate 20, but the arrangement pattern (arrangement rule) of the openings 14a of each cell 14 in the core body 12 may be arranged. It is preferable that they are regularly arranged according to the above. Further, only one through hole 22 may be formed in the perforated plate 20.

Further, the perforated plate 20 may be such that the through hole 22 does not induce Helmholtz resonance and can appropriately support the flow resistor 24. As long as that is the case, the thickness of the perforated plate 20 is not particularly limited, but is preferably 0.001 mm (1 μm) to 5 mm, more preferably 0.01 mm (10 μm) to 2 mm, for example. It is particularly preferably 0.1 mm (100 μm) to 1.0 mm.

Further, the planar shape and size (area) of the perforated plate 20 are not particularly limited, and may be appropriately set according to the place where the soundproof structure 10 is used, the environment, and the like.

Further, the shape of the through hole 22 is preferably circular in a plan view, but is not limited to this. The shape of the through hole 22 is a shape other than a circle, for example, a square, a rectangle, a rhombus, or a polygon, an ellipse, or an irregular shape including other quadrangles such as parallelograms and trapezoids, triangles, pentagons, and hexagons. May be. Further, the shape of the through hole 22 may be the same (constant) among all the through holes 22, or may be different among the through holes 22.

Further, the hole diameter (specifically, the diameter and the opening width) of the through hole 22 needs to be set within a range that does not hinder the air column resonance that occurs on the back surface side of the through hole 22 (that is, does not cause Helmholtz resonance). .. Here, the hole diameter of the through hole 22 can be defined in the same manner as the size of the opening 14a of the cell 14 of the core body 12.

To explain the hole diameter of the through hole 22 in more detail, the hole diameter of the through hole 22 needs to be 1.0 mm or more, preferably 5 mm or more, and more preferably 10 mm or more. The reason for limiting the hole diameter of the through hole 22 to 1.0 mm or more is that when the hole diameter of the through hole 22 is smaller than 1.0 mm, the viscous resistance in the inner wall surrounding the through hole 22 increases, and in that case, the flow resistor 24 is used. This is because if it is arranged on the through hole 22, the flow resistance (acoustic resistance) becomes excessive and the sound absorption characteristic may be significantly deteriorated.

The hole diameter of the through hole 22 is preferably 100 mm or less, more preferably 50 mm or less, and particularly preferably 25 mm or less. The reason for limiting the hole diameter of the through hole 22 to 100 mm or less is that if the hole diameter of the through hole 22 is larger than 100 mm, the rigidity of the perforated plate 20 is significantly reduced.

The hole diameter of the through hole 22 may be the same (constant) among all the through holes 22, and the hole diameter of some of the through holes 22 may be different from the hole diameters of the other through holes 22. That is, the perforated plate 20 may be provided with two or more types of through holes 22 having different hole diameters. If there is a distribution in the pore diameter, the average pore diameter may be adopted as the pore diameter to satisfy the above-mentioned size.

Further, the through hole 22 may be a straight hole having a uniform hole diameter over the entire length of the through hole 22, or may be a hole whose hole diameter changes along the depth direction of the through hole 22. .. Examples of the through hole 22 whose hole diameter changes include a tapered through hole 22. For the tapered through hole 22, the end with a larger hole diameter is located on the flow resistor 24 side (that is, the side closer to the sound source), and the end with a smaller hole diameter is on the core body 12 side (that is, the back side). It is preferably located at. In particular, in the through hole 22, the portion having the maximum hole diameter (maximum diameter portion) is located at one end of the perforated plate 20 in the thickness direction, and the portion having the minimum hole diameter (minimum diameter portion) is perforated in the thickness direction. A structure that is located at the other end of the plate 20 and whose hole diameter monotonically decreases from the maximum diameter portion to the minimum diameter portion is more desirable. As the size of the hole diameter of the through hole 22 whose hole diameter changes, the average value of the hole diameters of each part of the through hole 22 may be adopted.
Incidentally, the tapered through hole 22 can be formed by a physical method such as punching, and the through hole 22 formed by giving a taper by such a method also has many acoustic merits. Therefore, it is preferable.

Further, the aperture ratio of the through hole 22 in the perforated plate 20 is set within a range that does not hinder the air column resonance that occurs on the back surface side of the through hole 22 (that is, does not cause Helmholtz resonance), similar to the hole diameter of the through hole 22. There is a need. Here, the aperture ratio of the through hole 22 in the perforated plate 20 is the ratio of the area of the through hole 22 to the area of the closed space (air layer) behind the through hole 22, that is, the opening of the cell 14 of the core body 12. It can be defined as the ratio of the area of the through hole 22 to the cross-sectional area of the portion 14a (the area of the cross section whose normal is the thickness direction).

If the cross-sectional area of the opening 14a of the cell 14 of the core body 12 is not uniform, or if the area of the through hole 22 is not uniform, the average opening ratio of the through hole 22 is used as the opening ratio of the through hole 22. Use. Here, the average aperture ratio of the through holes 22 can be obtained as the ratio of the total area of all through holes 22 to the total area of all openings 14a in the core body 12. The total area of the total openings 14a can be calculated as the product of the number and the average area by obtaining the number and the average area of the total openings 14a within a predetermined range of the core body 12. The total area of all through holes 22 can be calculated as the product of the number and the average area by obtaining the number and average area of all through holes 22 within a predetermined range of the perforated plate 20.

The aperture ratio of the through hole 22 described above needs to be 1.0% or more, preferably 5.0% or more, for the reason that the air column resonance generated on the back surface side of the through hole 22 is not hindered. It is more preferably 10% or more, and particularly preferably 20% or more. Further, 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 material of the perforated plate 20 can support the flow resistor 24 on its surface, and can cover the opening surface of each of the plurality of cells 14 formed by the core body 12 on the opposite side of the back plate 18. As long as it is not particularly limited, specifically, the same material as the material of the core body 12 can be used. More specifically, examples of the material of the perforated plate 20 include paper materials, various metals such as aluminum and iron, and various resin materials such as polyethylene terephthalate (PET) and polypropylene (PP).

In the configuration described so far, the core body 12, the back plate 18, and the perforated plate 20 are different members from each other, but at least two of these members and the flow resistance body 24 described later are integrated. It may be made (strictly speaking, it may be an integrally molded product). For example, the perforated plate 20 and the core body 12 may be integrally molded using a 3D printer or the like, the core body 12 and the back surface plate 18 may be integrally molded, or the flow resistor 24 may be integrally molded. And the perforated plate 20 and the core body 12 may be integrally molded, or the perforated plate 20, the core body 12 and the back plate 18 may be integrally molded. Further, the entire soundproof structure 10 (that is, the flow resistance body 24, the perforated plate 20, the core body 12 and the back plate 18) may be integrally molded.

Further, in order to reduce the weight of the soundproof structure 10, it is preferable that at least one of the core body 12, the back plate 18 and the perforated plate 20 is made of a material in which voids are distributed inside. Here, the material in which the voids are distributed inside means a material in which a large number of fine voids are confirmed when the internal structure is microscopically observed, and specifically, a paper material such as corrugated cardboard. , Fiber aggregates such as thick cloth, and resin materials such as foamed plastic and closed cell urethane. By the way, in order to construct the air column resonance structure, it is necessary to make it difficult for sound to leak between the cells 14, and from that viewpoint, among the above materials, a non-breathable material such as closed-cell urethane or corrugated cardboard. A structure with low air permeability is desirable. In addition to such a structure, it is also possible to use a structure in which the air permeability is lowered by providing a non-breathable coating layer or film on the surface of the material in which the void portion is distributed inside.

In order to further reduce the weight of the soundproof structure 10, it is preferable that all of the core body 12, the back surface plate 18, and the perforated plate 20 are made of the above-mentioned material in which voids are distributed inside. .. Further, from the viewpoint of ease of molding and incineration, it is particularly preferable that the core body 12, the back plate 18, and the perforated plate 20 are all made of paper material.

[Flow resistor]
The flow resistance body 24 is overlapped with the perforated plate 20 on the side opposite to the core body 12 in the thickness direction, and forms the outermost layer in the soundproof structure 10. By covering the surface of the perforated plate 20 (the surface opposite to the core body 12) with the flow resistance body 24 in this way, the perforated plate 20 in which the through hole 22 is formed can be made invisible. .. This makes it possible to suppress deterioration of the aesthetics (design) and texture of the soundproof structure 10. In order to obtain such an effect, the surface of the flow resistor 24 (the surface in the thickness direction) has an area sufficient to cover the entire surface of the perforated plate 20 on the visual recognition side (the surface closer to the sound source in the thickness direction). It is good to be there.

Further, as described above, the flow resistance body 24 functions as a sound absorbing material in the soundproof structure 10. Specifically, when sound passes through the micropores 26 of the flow resistor 24, the sound energy is converted into heat energy by friction between the inner wall surface of the micropores 26 and air, and the sound is absorbed.

The flow resistance body 24 may be made of a fine through-hole plate or a porous sound absorbing material in order to exert a function as a sound absorbing material as described above. More preferably, the flow resistor 24 may be composed of a fiber aggregate such as cloth and paper. Further, from the viewpoint of reducing the weight of the soundproof structure 10, the flow resistance body 24 is preferably made of cloth.

Examples of the cloth constituting the flow resistor 24 include woven cloth, knitted cloth, and non-woven fabric. Further, using a fiber having a fiber diameter of submicron order (order of 1 to 100 nm) as the fiber of the cloth constituting the flow resistor 24 is thinner than the conventional non-woven fabric and a high sound absorption effect can be obtained. preferable. Examples of the non-woven fabric constituting the flow resistor 24 include thinsulate (trademark, manufactured by 3M), sound-absorbing felt, and non-woven fabric made of metal fiber (Poal (manufactured by Unix)). Further, as an example of the woven fabric constituting the flow resistor 24, broad (plain weave), non-combustible cloth (manufactured by Istflon Co., Ltd. IST) and the like can be mentioned.

The cloth fibers constituting the flow resistor 24 include aramid fiber, glass fiber, cellulose fiber, nylon fiber, vinylon fiber, polyester fiber, polyethylene fiber, polypropylene fiber, polyolefin fiber, rayon fiber, low density polyethylene resin fiber, and ethylene. Vinyl acetate resin fiber, synthetic rubber fiber, copolymerized polyamide resin fiber, fiber made of resin material such as copolymerized polyester resin fiber, fiber made of metal material such as stainless steel fiber, fiber of carbon material, fiber of carbon-containing material, etc. Can be mentioned.

Examples of the porous sound absorbing material other than the cloth constituting the flow resistor 24 include glass wool, rock wool, urethane foam, gypsum board and the like.

The flow resistor 24 has a plurality of micropores 26 as shown in FIG. Each microhole 26 forms a ventilation portion, and the microhole 26 is formed in the flow resistor 24, so that the through hole 22 of the perforated plate 20 and the closed space (air) behind the through hole 22 are formed. The layer) communicates with the outer space of the flow resistor 24.

In the cloth constituting the flow resistor 24, the micropores 26 are spaces between fibers and are three-dimensionally arranged in a mesh pattern. That is, in the cloth constituting the flow resistor 24, the average diameter and the average aperture ratio of the micropores 26 are determined by the fiber diameter and the density. Here, the average diameter and the average aperture ratio of the micropores 26 are not particularly limited as long as the flow resistance of the flow resistor 24 is 350 to 1500 Pa · s / m, and can be arbitrarily set. Is.

Incidentally, when the flow resistance body 24 is composed of a fine through hole plate, the fine hole 26 becomes a fine through hole penetrating in the thickness direction. In this case, the planar shape, diameter (size), and arrangement position of the micropores 26 are not particularly limited. Further, the micropores 26 may be drilled regularly or randomly. Further, the diameters of the micropores 26 may be the same among all the micropores 26, and the diameters of some of the micropores 26 may be different from the diameters of the other micropores 26. That is, the micropores 26 may be formed in the microthrough hole plate having two or more kinds of diameters. In this case, the preferable range of the average diameter is preferably 1.0 μm to 250 μm, more preferably less than 100 μm, further preferably 80 μm or less, still more preferably 70 μm or less, still more preferably 50 μm or less, and further preferably 30 μm in order to improve the sound absorption performance. The following are particularly preferred. Here, the diameter of the micropores 26 can be evaluated using the diameter of a circle (diameter equivalent to a circle) having the same area as the area of the micropores 26.

The material of the fine through-hole plate constituting the flow resistance body 24 is not particularly limited, and the same material as the core body 12 described above can be used. Specific materials for the fine through-hole plate include, for example, aluminum, titanium, nickel, polymerloy, 42 alloy, coval, nichrome, copper, beryllium, phosphorus bronze, brass, white, tin, zinc, iron, tantalum, and niobium. , Molybdenum, zirconium, gold, silver, platinum, palladium, steel, tungsten, lead, stainless steel, and various metals such as iridium, and alloy materials combining the above-mentioned various metals; PET (polyethylene terephthalate), TAC (triacetyl cellulose). ), Polyvinyl chloride den, polyethylene, polyvinyl chloride, polymethylbenzene, COP (cycloolefin polymer), polycarbonate, zeonoa, PEN (polyethylene naphthalate), polypropylene, and polyimide, ABS resin (Acrylonitrile), butadiene ( Butadiene), styrene (Styrene) copolymer synthetic resin), resin materials such as PLA resin, and the like can be used. Further, fiber reinforced plastic materials such as carbon fiber reinforced plastic (CFRP) and glass fiber reinforced plastic (GFRP), and glass materials such as thin film glass can also be used.

When the material constituting the flow resistance body 24 is a metal material, the flame retardancy of the soundproof structure 10 can be improved. This effect is particularly effective when the core body 12, the back plate 18, and the perforated plate 20 are made of a flammable material such as paper. Incidentally, among the metal materials, copper, nickel, stainless steel, titanium and aluminum are preferable from the viewpoint of cost and availability. In particular, it is most preferable to use aluminum and an aluminum alloy from the viewpoints of light weight, easy formation of fine pores by etching and the like, and availability and cost.

If the flow resistor 24 is made of a metal material, the ozone resistance can be improved and the radio wave can be shielded. Further, since the flow resistor 24 made of a metal material has conductivity and is difficult to be charged, fine dust and dirt are not attracted to the membrane by static electricity, and dust and dust are not attracted to the fine holes 26 of the flow resistor 24. It is possible to prevent the sound absorption performance from being deteriorated due to clogging. Furthermore, since the metal material has a high reflectance to radiant heat due to far infrared rays, the flow resistor 24 made of the metal material also functions as a heat insulating material for preventing heat transfer due to radiant heat. At that time, since the flow resistance body 24 is formed with a large number of fine holes 26 having a relatively small diameter, the flow resistance body 24 functions as a reflective film against radiant heat.

Further, when a metal material is used as a material constituting the flow resistance body 24, it is preferable to perform metal plating on the surface from the viewpoint of suppressing rust and the like. At this time, the average diameter of the micropores 26 may be adjusted to be smaller by applying metal plating to at least the inner wall surface of the micropores 26.

In the soundproof structure 10 of the present invention, the flow resistance of the flow resistance body 24 is 350 Pa · s / m or more and 1500 Pa · s / m. As a result, as described above, the wide-band sound absorption effect caused by the ventilation portion composed of the micropores 26 of the flow resistor 24 and the sound absorption peak frequency due to the mass of the frame portion of the flow resistor 24 toward the low frequency side. A shift effect can be realized. As a result, according to the soundproof structure 10 of the present invention, it is possible to absorb relatively low frequency sound like a human voice in a wide band.

For the flow resistance of the flow resistance body 24, the air flow rate per unit area of the flow resistance body 24 with respect to the surface of the flow resistance body 24 is 0.4 cc / cm2 / using a ventilation resistance measuring device (KES F-8 manufactured by Kato Tech Co., Ltd.). It can be measured by setting it to s. This method is a method of measuring the aeration resistance by a method of constant aeration amount, and a step of sandwiching a flow resistor 24 in a measuring part and discharging air to the atmosphere through a sample with the above aeration amount, and the above-mentioned method. Similarly, it is composed of two steps of sucking the sample from the air to the device side, and it is a method of measuring the flow resistance by measuring the pressure at each step. When the flow resistance is not uniform in the surface of the surface of the flow resistance body 24, the average value of the flow resistance of each part of the surface may be adopted as the flow resistance of the flow resistance body 24. For example, three points in the cloth constituting the flow resistance body 24 can be measured, and the average value thereof can be adopted as the flow resistance. Incidentally, in Example 1 described later, it was confirmed that the acoustic characteristics can be reproduced well when the values actually measured by the above method are used.
In addition, when multiple members with different flow resistance are used, such as attaching multiple cloths of different types to different places, or when the flow resistance is different for each region, each member or region has its own. Make the above measurements. If at least one of them satisfies the above numerical range, the effect of the present invention can be obtained in that region.
Regarding the flow resistance, the flow resistance may be measured by using a system such as "Flow resistance measurement system AirReSys" manufactured by Nippon Acoustic Engineering. The method adopted by this system is the method specified in ISO 9053 (ISO 9053-1: 2018 as of 2018), and as long as this method is followed, it is possible to measure with other devices.

The flow resistance of the flow resistor 24 is preferably 350 Pa · s / m or more, preferably 1100 Pa · s / m, more preferably 400 Pa · s / m or more, and more preferably 1000 Pa · s / m, and more preferably 500 Pa · s / m. Most preferably m or more and 900 Pa · s / m.

Further, among the characteristics of the flow resistor 24, the surface density affects the sound absorption performance, specifically, the frequency at which the sound absorption coefficient is maximum with respect to a predetermined flow resistance, and the sound absorption coefficient at that frequency. (Ie, maximum sound absorption coefficient) is affected (see, for example, FIG. 14). In order to make the maximum sound absorption coefficient 95% or more, it is preferable that the surface density of the flow resistor 24 is 50 g / m ² or more. More preferably, the surface density of the flow resistor 24 is 60 g / m ² or more and 500 g / m ² or less. Further, regarding the lower limit of the surface density of the flow resistor 24, if it is 70 g / m ² or more, the maximum sound absorption coefficient can be more than 99%, and more preferably 100 g / m ² . On the other hand, the upper limit of the surface density of the flow resistor 24 is preferably 400 g / m ² , more preferably 300 g / m ² .

The surface density can be obtained by measuring the size (area) of the surface of the flow resistor 24 and measuring the weight of the flow resistor 24 by a usual measuring method. Regarding the surface area of the flow resistor 24, the area in the form used for the soundproof structure is measured. Specifically, when the flow resistor 24 made of a material that stretches well is stretched and pasted, the area in the stretched state is measured. In this case, it is basically equal to the area of the perforated plate 20 arranged on the back surface of the flow resistor 24. Then, after measuring the area, if the size is large, the flow resistor 24 is folded, and the weight is measured using a scale in that state. Then, the surface density of the flow resistor 24 can be obtained by calculating (measured weight) / (measured area).
If it is not possible to measure by weighing because the overall size of the flow resistance body 24 is large and the flow resistance body 24 cannot be folded, a part of the flow resistance body 24 may be cut out and measured. The area to be cut out at that time is not particularly limited, but for example, it can be cut out into a square shape of 10 cm × 10 cm and the weight can be measured.
Also, as in the case of flow resistance measurement, when multiple members with clearly different flow resistance are used or the flow resistance is completely different for each region, such as when multiple cloths of different types are attached to different places. Performs the above measurement for each member or region. If at least one of them satisfies the above numerical range, the effect of satisfying the above numerical range can be obtained in that region.

The thickness of the flow resistor 24 is not limited, but the thinner the flow resistor 24, the more preferable it is from the viewpoint of miniaturization, weight reduction, air permeability, and light transmission. Further, when etching or the like is used as a method for forming the fine pores 26, the thicker the base material of the flow resistor 24, the longer it takes to produce the material. Therefore, it is desirable that the material is thinner from the viewpoint of productivity. From the above, the thickness of the flow resistor 24 is preferably 50 mm or less, more preferably 25 mm or less, further preferably 20 mm or less, further preferably 10 mm or less, further preferably 5 mm or less, even more preferably 2 mm or less, and less than 1 mm. Most preferred. Examples of the flow resistance body 24 having a thickness of less than 1 mm include a sheet-like body made of a woven cloth, a knitted cloth, a non-woven fabric, and the like, and a film-like body.

On the other hand, if the flow resistor 24 becomes too thin, the flow resistor 24 is liable to be mechanically damaged. Therefore, the flow resistor 24 is preferably 0.1 μm or more, more preferably 1.0 μm or more, and 10 μm or more. Is more preferable.

The planar shape and size (area) of the flow resistance body 24 are not particularly limited, but may be appropriately set according to the planar shape and size of the core body 12 and the perforated plate 20. By the way, the flow resistance body 24 can only cover the entire opening surface of each of the plurality of cells 14 formed by the core body 12 in a state of being stacked on the core body 12 via the perforated plate 20 in the thickness direction. It is preferable to have an area.

The flow resistor 24 made of a porous material such as cloth has functions other than sound absorption, such as flame retardancy, design, waterproofness, water repellency, oil repellency, stain resistance, wear resistance, and weather resistance. For the purpose of imparting properties, shape retention, and the like, processing for modifying the properties of flow resistance may be performed. Since the soundproof structure 10 using the flow resistor 24 subjected to the above processing can be installed in a place where the soundproof structure has not been used in the past, and can be used in that place. , Market value and usefulness increase.

On the other hand, depending on the processing method, the air permeability and sound absorption of the flow resistor 24 may be lowered. In order to maintain the sound absorption property of the flow resistance body 24, it is necessary to select an appropriate processing method with respect to the characteristics (characteristics to be modified) imparted to the flow resistance body 24. That is, as the cloth constituting the flow resistor 24, there is a demand for a cloth that has been processed to impart desired characteristics while maintaining sound absorption. As the cloth constituting the flow resistor 24, there is a cloth on which a predetermined image is printed in order to improve the design, but the type (fabric) of the cloth is limited, and further, when a printing request is made. Since image submission is required, processing costs and labor will increase.

For the above reasons, when the cloth constituting the flow resistor 24 is processed in the present invention, among the mechanical properties on the surface of the cloth, the physical properties related to sound absorption (specifically, the flow resistance, the fiber strength, etc.) It is preferable to use a method that can maintain the aperture ratio, knot ratio, etc.). In other words, the flow resistor 24 of the present invention may have a processed portion that has been processed to modify the properties of the flow resistor 24. Here, the flow resistance of the processed portion after processing is preferably 350 Pa · s / m or more and 1500 Pa · s / m or less. By setting the flow resistance after processing to 350 Pa · s / m or more and 1500 Pa · s / m or less in this way, a high sound absorption effect can be obtained. By applying the water-repellent treatment to the flow resistor 24 in such a configuration, not only the flow resistor 24 but also the perforated plate 20 and the core body 12 on the back surface thereof are subjected to water or other liquid (hereinafter referred to as water). Etc.) can be protected from water when it is hung. As a result, the range of choices for the materials of the perforated plate 20 and the core body 12 can be expanded to materials having low durability against water, and for example, paper or the like can be used. Further, it is possible to prevent water or the like from accumulating in the opening 14a of the cell 14 of the core body 12. As described above, by applying the water-repellent treatment to the flow resistance body 24 as described above, it is possible to protect not only the flow resistance body 24 but also the entire soundproof structure 10.

To give a specific example, the flow resistance of the cloth before processing is 350 to 1500 Pa · s / m, which imparts design to the cloth (for easy understanding, an image or a pattern is provided on the processed portion). Examples of the method (attachment) include dyeing with a dye, coloring with a paint, and transfer of a printed film. Of these, in dye dyeing, the mechanical properties of the cloth surface related to sound absorption are less likely to change before and after processing. On the other hand, in paint coloring and film transfer, the mechanical properties of the cloth surface related to sound absorption change due to processing, and the flow resistance after processing tends to decrease. Therefore, dye dyeing is considered to be preferable as a processing method for adding an image or a pattern to the processed portion.

To explain with another example, as a water-repellent treatment for imparting water repellency to a cloth having a flow resistance of 350 to 1500 Pa · s / m, a method of laminating a water-repellent coating layer on the cloth surface and a method of laminating a water-repellent coating layer on the cloth surface and Examples thereof include a method of immersing a cloth in a chemical solution to chemically bond a water-repellent component to the fibers of the cloth. In the former method, the mechanical properties of the cloth surface related to sound absorption (particularly, the physical properties related to air permeability) tend to deteriorate after processing, but in the latter method, changes in the mechanical properties are suppressed. Therefore, as a method of imparting water repellency to the processed portion, a method of chemically binding the water repellent component to the fibers of the cloth fabric is considered to be preferable.

Examples of the processing applied to the processed portion include other than the above-mentioned dyeing processing and water-repellent processing, for example, printing processing, sublimation transfer processing, brushing processing, antibacterial processing, water absorption processing, quick-drying processing, morphological stabilization processing, Wrinkle-proof processing, photocatalytic processing, UV-cutting processing, dust-proof processing, cool feeling processing, negative ion processing, flame-proof processing, pollen adhesion prevention processing, and pest repellent processing are included, and at least one of these is applied to the processed part. It suffices if it has been done.

The ratio of the region belonging to the processed portion in the surface to the surface of the flow resistor 24 in the thickness direction (strictly speaking, the surface having the surface opposite to the perforated plate 20) is often more than 5%. , 30% or more is more preferable, and 70% or more is particularly preferable. That is, the flow resistance body 24 may include a processed portion and a non-processed portion, and the flow resistance (breathability) may be the same between the processed portion and the non-processed portion.

The method of fixing the flow resistance body 24 in the soundproof structure 10 will be described. The method of fixing the flow resistance body 24 is not particularly limited. For example, the flow resistance body 24 and the perforated plate 20 may be adhered and fixed, and in this case, the rigidity of the flow resistance body 24 can be further increased. The adhesive used for adhering the flow resistance body 24 and the perforated plate 20 may be selected according to the material of the flow resistance body 24, the material of the perforated plate 20, and the like. Examples of adhesives 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.

Other methods for fixing the flow resistor 24 and the perforated plate 20 include, for example, a method of fixing with fasteners such as screws, thumbtacks, screws and staplers, and a method for fixing the flow resistor 24 and the perforated plate. Examples thereof include a method of fixing with an adhesive tape, a magnet or a hook-and-loop fastener arranged between the 20 and the perforated plate 20, and a method of sewing and fixing the flow resistor 24 to the perforated plate 20. Further, the flow resistor 24 may be directly fixed to the perforated plate 20. Alternatively, the flow resistance body 24 is indirectly fixed to the perforated plate 20 by wrapping both end portions of the flow resistance body 24 around the back side of the soundproof structure 10 and fastening them to the core body 12 and the back plate 18. You may.

In the soundproof structure 10 shown in FIG. 1, the flow resistance body 24 and the perforated plate 20 are in contact (bonded) with each other without a gap in the thickness direction, but the present invention is not limited to this, and the perforated plate 20 is not limited to this. A gap may be provided between the flow resistor 24 and the flow resistor 24. In this way, by providing a gap between the flow resistance body 24 and the perforated plate 20, vibration of the flow resistance body 24 can be induced, and the sound absorption characteristics on the low frequency side can be improved. Here, the gap between the flow resistance body 24 and the perforated plate 20 is preferably more than 0 mm and preferably 10 mm or less, more preferably 0.1 mm or more and 5 mm or less, and more preferably 0.5 mm or more. Is most preferable. Further, when a gap is provided between the flow resistance body 24 and the perforated plate 20, not only when the entire surface of the flow resistance body 24 is separated from the perforated plate 20, a part of the flow resistance body 24 comes into contact with the perforated plate 20. You may.

<< About the soundproof panel of the present invention >>
Next, the soundproof panel of the present invention configured by using the above-mentioned soundproof structure 10 will be described with reference to the configuration of the illustrated soundproof panel B in FIG. 4 as an example. FIG. 4 is a perspective view showing the soundproof panel B.

As shown in FIG. 4, the soundproof panel B has a panel body Bx configured by the soundproof structure 10 and a frame body By surrounding the panel body, and is a panel material having sound absorbing performance (that is, a sound absorbing panel). Is. The soundproof panel B shown in FIG. 4 is partially composed of the soundproof structure 10, but the present invention is not limited to this, and the entire soundproof panel B is composed of the soundproof structure 10. May be good. Further, of the panel body Bx and the frame body By, only the frame body By may be configured in the soundproof structure 10.

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

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

The soundproof enclosure structure is configured by arranging a plurality of panel materials including the soundproof panel B as an outer peripheral wall (that is, a partition), and by arranging a sound source in the space inside the outer wall (that is, a partition), a sound absorbing effect on noise is exhibited. do. The soundproof enclosure structure is not limited to the one in which the soundproof panels B are arranged in a ring shape so as to surround the sound source, and may be a partition composed of one or two panels. Further, the soundproof enclosure structure may be used in a form of being attached to a chair, a desk or the like.
The soundproof room is a room configured by using a plurality of panel materials including the soundproof panel B as a room wall, and exhibits a sound absorbing effect against the voice of a person who is active indoors or the noise generated outdoors.
The sound source described above may be a device that emits sound or a human voice.

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

[Example 1]
<Making a soundproof structure>
The soundproof structure shown in FIG. 1 was produced. Specifically, as the core body, a honeycomb core (manufactured by Core Pack Nishikawa) made of corrugated cardboard having a thickness of 30 mm and a plane size of the opening of the cell of 12 mm was prepared. A paper back plate (manufactured by Core Pack Nishikawa) having a thickness of 1.0 mm and having no through holes was adhered and fixed to one side of the honeycomb core. Further, a perforated plate made of paper having a thickness of 1.0 mm formed so that a through hole having a diameter of 2 mm had an aperture ratio of 20% was adhered and fixed to the other side of the honeycomb core. Further, as a flow resistor, the thickness is 240 μm, the density is 0.59 g / cm ³ , the surface density is 142 g / m ² , the porosity is 0.63, and the flow resistance is 833 Pa · s. A color broad cloth (plain weave cloth) with / m was prepared. This color broad cloth was adhered and fixed on the perforated plate. As an adhesive for adhering the members to each other, spray glue 77 (manufactured by 3M) was used.

Incidentally, the flow resistance of the color broad cloth was measured at a ventilation rate of 0.4 cc / cm ² / s using a ventilation resistance measuring device KES F-8 manufactured by Katou Tech. The surface density of the color broad cloth was determined by measuring the cloth size and then measuring the mass with a normal weight.

<Evaluation>
The soundproof structure produced by the above procedure was arranged so that the color broad cloth faced the sound source side, and the sound absorption coefficient was measured with an acoustic tube. As the acoustic tube measurement method, a measurement system for the vertical incident sound absorption coefficient using two microphones was prepared and evaluated according to "JIS A 1405-2". The internal diameter of the acoustic tube was set to 4 cm, and a system capable of measuring up to about 4000 Hz was used. The same measurement can be performed using WinZac MTX manufactured by Nippon Acoustic Engineering.

The sound absorption coefficient measured for the produced soundproof structure is shown in FIG. Note that FIG. 5 also shows the calculation results of Simulation 1, which will be described later. As shown in FIG. 5, it was found that in the produced soundproof structure, a maximum value (peak) of a high sound absorption coefficient appears in the vicinity of 1200 Hz, and sound can be absorbed in a wide frequency band. Here, in the produced soundproof structure, since the distance of the back space behind the through hole of the perforated plate is 30 mm, the corresponding air column resonance frequency is 2860 Hz. It can be seen that the sound absorption peak frequency of the produced soundproof structure is shifted to the low frequency side by 10% or more with respect to this frequency by using a color broad cloth having a relatively high flow resistance. Incidentally, in the calculation result shown in FIG. 5, the shift amount is 1660 Hz, which corresponds to the shift amount of 58% with respect to the corresponding air column resonance frequency.

[Simulation 1]
The sound absorption coefficient of the soundproof structure of the present invention was examined by simulation using the finite element method software COMSOL ver5.3 (COMSOL Inc.). In the simulation, the back plate and core body were modeled as rigid bodies. In addition, the plate part of the perforated plate was also treated as a rigid body. A thermoacoustic model was applied to the through-hole part of the perforated plate to incorporate frictional sound absorption. However, it was found that the presence or absence of frictional sound absorption does not have a significant effect on the simulation results in a system in which a through hole having a large aperture ratio and an order of mm or more is provided as in the present invention.

Regarding the modeling of the flow resistor, as a result of diligent studies by the inventors, not only the frictional heat absorption model of the micropores (ventilation part) of the flow resistor but also the vibration of the frame (material part) of the flow resistor is simulated. It was clarified that the experimental results can be reproduced extremely well by incorporating them into the model. The simulation result is shown in FIG.

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

However, the present inventor has shown that it is difficult to satisfactorily reproduce the experimental results of a flow resistor having a large flow resistance in the above model. FIG. 6 shows a calculation result (shown by a broken line in FIG. 6) when the sound absorption coefficient of the soundproof structure produced in Example 1 was calculated using the Ridid model. As can be seen by comparing FIGS. 5 and 6, it is clear that neither the sound absorption coefficient nor the sound absorption band at the sound absorption peak frequency can reproduce the measured values.

Therefore, the present inventor has adopted the Biot model in order to calculate even the vibration of the frame in the flow resistor. In both the calculation result (simulation result) shown by the broken line in FIG. 5 and the calculation result shown by the solid line in FIG. 6, the parameters of the soundproof structure prepared in Example 1 are applied to the Biot model. It is the result of calculation. As can be seen from FIG. 5, it is clear that the measured values of Example 1 are well reproduced by calculating including the vibration of the frame in the flow resistor.

Further, as can be seen from FIG. 6, it is clear that the calculation result of the sound absorption coefficient greatly differs depending on whether or not the vibration of the frame is incorporated. This is because, in the case of a flow resistor having a high flow resistance, the ventilation resistance in the ventilation part of the flow resistance becomes high, so that a part of the sound that is difficult to pass through the ventilation part vibrates the frame. It is probable that the vibration contributed to the sound absorption coefficient.

Incidentally, FIG. 7 shows the results when the simulation was carried out with the flow resistance set to 100 Pa · s / m and the other conditions aligned with the simulation conditions of FIG. As shown in FIG. 7, it was clarified that there is almost no difference in sound absorption coefficient between the Rigid model and the Biot model in the flow resistor having a low flow resistance of about 100 Pa · s / m. From this, it is considered that the effect of lowering the sound absorption peak frequency by the flow resistor is an effect peculiar to the case where the flow resistance is high.

[Simulation 2]
The effect of flow resistance was examined by simulation using the above-mentioned Biot model. Specifically, the thickness was 240 μm, the surface density was 144 g / m ² , and the flow resistance was changed by 50 Pa · s / m from 50 to 3000 Pa · s / m, and the sound absorption coefficient at each frequency was calculated. The parameters related to the core body and the perforated plate are the same as the parameters in Simulation 1.

FIG. 8 shows the calculation results of the sound absorption coefficient when the flow resistance is 100, 500, 800 and 3000 Pa · s / m. As can be seen from FIG. 8, in the case of low flow resistance, the sound absorption coefficient at each frequency becomes small, and the sound absorption peak frequency is on the higher frequency side. On the other hand, by increasing the flow resistance, the sound absorption coefficient at each frequency is increased, and the sound absorption peak frequency is lowered. However, when the flow resistance is the highest condition value (= 3000 Pa · s / m), the sound absorption coefficient becomes lower in frequency, but the sound absorption band becomes slightly narrower. From this, it can be seen that it is necessary to set the flow resistance in an appropriate range in order to effectively absorb low frequency sound in a wide band.

Further, FIG. 9 shows the maximum sound absorption coefficient for each flow resistance. As can be seen from FIG. 9, when the flow resistance is 350 Pa · s / m or more, the maximum sound absorption coefficient is 98% (17 dB when converted to mute volume) or more, and the flow resistance varies slightly depending on the change in the flow resistance. The maximum sound absorption coefficient is maintained at 98% or more until it reaches 1900 Pa · s / m.

Further, FIG. 10 shows the results of evaluating the sound absorption peak width satisfying the sound absorption rate of 50% (3 dB in terms of muffling volume) or more for each flow resistance. When the flow resistance is 800 Pa · s / m, the sound absorption peak width becomes the maximum value, and the sound absorption coefficient of 50% or more is satisfied in the frequency band of about 4000 Hz. Then, with reference to 3500 Hz, which is about 500 Hz smaller than the above-mentioned sound absorption peak width, the range of flow resistance at which a sound absorption peak width equal to or larger than that width can be obtained is 350 to 1500 Pa · s / m, as can be seen from FIG. From this, it was clarified that a high sound absorption coefficient and a wide band sound absorption peak width can be realized by setting the flow resistance to 350 Pa · s / m or more and 1500 Pa · s / m or less.

Further, FIG. 11 shows the sound absorption peak frequency for each flow resistance. As is clear from FIG. 11, the sound absorption peak frequency decreases as the flow resistance increases. Here, when the degree of change in the sound absorption peak frequency (strictly speaking, the differential value) is obtained for each flow resistance, as shown in FIG. 12, the sound absorption peak frequency does not change to a certain degree, but the flow resistance is 600 Pa. It was found that it changed rapidly near s / m. FIG. 12 is a diagram showing the result of differentiating the sound absorption peak frequency by the flow resistance. In the figure, the horizontal axis represents the flow resistance, and the vertical axis represents the differential value (unit: Hz / (Pa · s / m)). ).

Further, it is evaluated how much the sound absorption peak frequency obtained for each flow resistance is lowered from the reference frequency, and the evaluation result is shown in FIG. Specifically, when the flow resistance is an extremely low value (specifically, 10 Pa · s / m), the sound absorption peak frequency is near the resonance frequency of the air column resonance (specifically, 2280 Hz). Using this frequency as the reference frequency, the rate of change F below is used to determine how low the sound absorption peak frequency at each flow resistance (strictly speaking, except when it is 10 Pa · s / m) is lower than the reference frequency. It was evaluated by calculating.
F = {1- (sound absorption peak frequency at each flow resistance / reference frequency)} x 100

As is clear from FIG. 13, it was found that when the flow resistance becomes 350 Pa · s / m or more, the sound absorption peak frequency becomes 10% or more lower than the reference frequency. From this, it was clarified that by setting the flow resistance to 350 Pa · s / m or more, a high sound absorption coefficient and a wide band sound absorption peak width can be realized, and the sound absorption peak frequency can be sufficiently lowered.

[Simulation 3]
In order to examine the effect of the surface density of the flow resistor, the effect of changing the flow resistance and surface density of the flow resistor was simulated. The basic configuration of the soundproof structure adopted in the simulation is the same as in simulations 1 and 2 described above. Further, the flow resistance was changed in the range of 200 to 1600 Pa · s / m, the surface density was changed in the range of 10 to 1000 g / m ² , and the sound absorption coefficient at 100 to 10000 Hz was calculated every 10 Hz under each condition. ..
Then, from the calculation results obtained by the above simulation, (1) the sound absorption peak frequency which is the maximum sound absorption coefficient (hereinafter, simply referred to as the sound absorption peak frequency), (2) the maximum sound absorption coefficient, and (3) the sound absorption coefficient is 80%. The frequency width (sound absorption peak width) in the range exceeding the above was calculated. The respective calculation results are shown in FIGS. 14 to 16. Each of FIGS. 14 to 16 is a diagram showing the change in the above calculation result in shades of color when each of the flow resistance and the surface density of the flow resistor is changed.

Further, from the above calculation results, the results when the flow resistance is 800 Pa · s / m are extracted and shown in FIGS. 17 and 18. FIG. 17 shows the change in the sound absorption peak frequency when the surface density of the flow resistor is changed. FIG. 18 shows the change in the maximum absorption rate when the surface density of the flow resistor is changed.

Regarding the sound absorption peak frequency, the conditions for lowering the frequency are determined according to the flow resistance and the surface density. Basically, as shown in FIG. 14, there is a positive correlation between the flow resistance and the areal density that lower the sound absorption peak frequency.

On the other hand, regarding the maximum sound absorption coefficient, as shown in FIG. 15, there may be a region where the maximum sound absorption coefficient is relatively high in the range where the flow resistance is 350 Pa · s / m or more. More specifically, when the flow resistance is between 350 and 600 Pa · s / m, the maximum sound absorption coefficient is close to 1.0 regardless of the surface density. When the flow resistance is 600 Pa · s / m or more, the maximum sound absorption coefficient depends on the surface density, and the range of the surface density at which a relatively high maximum sound absorption coefficient can be obtained is limited.
Further, in the range where the flow resistance is up to 1000 Pa · s / m, there is an overlap (overlapping range) between the condition for lowering the sound absorption peak frequency and the condition for obtaining a relatively high maximum sound absorption coefficient. Therefore, high sound absorption performance and low frequency of sound absorption peak frequency can be achieved at the same time. On the other hand, when the flow resistance becomes larger than 1000 Pa · s / m, a deviation occurs between the condition for lowering the sound absorption peak frequency and the condition for obtaining a relatively high maximum sound absorption coefficient, and the deviation width becomes. It increases as the flow resistance increases.

Further, regarding the sound absorption peak width, as shown in FIG. 16, when the flow resistance is 1100 Pa · s / m or less, there is a condition that the sound absorption peak width (band) becomes large even if the surface density is large. In particular, when the flow resistance is about 600 to 800 Pa · s / m, the sound absorption peak width (band) becomes the largest. On the other hand, when the flow resistance becomes larger than 1100 Pa · s / m, there are many conditions where the sound absorption coefficient does not reach 80% at all, and even under other conditions, the sound absorption peak width (band) becomes small.

As described above, as a condition for lowering the sound absorption peak frequency, it is conceivable to increase both the flow resistance and the surface density of the flow resistor. Further, as a condition for setting the maximum sound absorption coefficient to a high value (for example, a value close to 1.0), the flow resistance of the flow resistor is set in the range of 350 to 600 Pa · s / m, or it. With the above flow resistance, it is conceivable to reduce the surface density to about 60 to 200 g / m ² or less. Further, as a condition for widening the sound absorption peak width, it is conceivable that the flow resistance of the flow resistor is in the range of 50 to 1100 Pa · s / m, or the surface density is set to 60 to 500 g / m ² .
Regarding the flow resistance and surface density of the flow resistor, an appropriate condition is selected from the various conditions (specifically, the above range) described above.
Here, considering the conditions of the flow resistance and the surface density from the various viewpoints described above as the conditions for exerting the effect of the present invention, the flow resistance of the flow resistor is 350 Pa · s / m to 1500 Pa ·. It is necessary that the surface density is s / m and the surface density of the flow resistor is 60 to 500 g / m ² . Since the soundproof structure of the present invention has a relatively small structure but absorbs relatively low frequency sound in a wide band, it is necessary to satisfy the above numerical range. In FIG. 17, the range shown by the solid line corresponds to the range of the surface density for exerting the effect of the present invention.

Further, the flow resistance is preferably in the range of 350 to 1100 Pa · s / m, that is, as a condition for increasing the sound absorption peak width (band). Furthermore, the flow resistance is in the range of 400 to 1000 Pa · s / m, that is, as a condition for realizing a low frequency of the sound absorption peak frequency and a high sound absorption coefficient while increasing the sound absorption peak width (band). Is more preferable. In particular, the flow resistance is most preferably in the range of 500 to 900 Pa · s / m, that is, as a condition for further increasing the sound absorption peak width (band).

Regarding the surface density, considering the calculation result of the maximum sound absorption coefficient shown in FIG. 18, the upper limit is preferably 400 g / m ² , and more preferably 300 g / m ² . The lower limit is preferably 70 g / m ² or more, and more preferably 100 g / m ² for the reason of effectively lowering the sound absorption peak frequency.
As described above, by setting the flow resistance and surface density of the flow resistor within the above numerical range, it is possible to realize a low frequency of the sound absorption peak frequency, high sound absorption performance, and a wide band sound absorption structure. Is possible.

Since each of Example 1 and Simulations 1 to 3 described above are within the scope of the present invention, the effect of the present invention is clear.

10 Soundproof structure 12 Core body 14 Cell 14a Opening 14b Partition wall 18 Back plate 20 Perforated plate 22 Through hole 24 Flow resistor 26 Fine hole B Soundproof panel Bx Panel body By frame

Claims (11)

The core body that composes multiple cells and
A back plate covering the opening surface of each of the plurality of cells in the thickness direction of the core body,
A perforated plate that covers the opening surface of each of the plurality of cells at a position opposite to the back plate in the thickness direction and has a through hole formed therein.
It has a flow resistor that is laminated on the perforated plate at a position opposite to the core body in the thickness direction and has air permeability.
Sounds in the frequency band including the frequency of human voice are targeted for sound absorption.
A soundproof structure characterized in that the flow resistance of the flow resistor is 350 Pa · s / m or more and 1500 Pa · s / m or less. The soundproof structure according to claim 1, wherein the surface density of the flow resistor is 60 g / m ² or more and 500 g / m ² or less. The soundproof structure according to claim 1 or 2, wherein the flow resistor is made of a fine through-hole plate or a porous sound absorbing material. The soundproof structure according to any one of claims 1 to 3, wherein the flow resistor is made of cloth. The soundproof structure according to any one of claims 1 to 4, wherein the flow resistor has a thickness of less than 1 mm. The soundproof structure according to any one of claims 1 to 5, wherein the core body is a honeycomb core. The soundproof structure according to any one of claims 1 to 6, wherein at least one of the core body, the back plate, and the perforated plate is made of a material in which voids are distributed inside. The soundproof structure according to claim 7, wherein the core body, the back plate, and the perforated plate are all made of the material in which voids are distributed inside. The soundproof structure according to claim 8, wherein the core body, the back plate, and the perforated plate are all made of paper material. The flow resistor has a processed portion that has been processed to modify the characteristics other than the sound absorption performance of the flow resistor.
The soundproof structure according to any one of claims 1 to 9, wherein the flow resistance of the processed portion after processing is 350 Pa · s / m or more and 1500 Pa · s / m or less. A soundproof panel configured by the soundproof structure according to any one of claims 1 to 10.

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