JP3932156B2 - Sound absorbing structure and sound absorbing plate - Google Patents

Description

注： EM はエキスパンドメタル、 PM はパンチングメタルの略号。
【００２６】
【表２】

注：多孔質材(1) は、最前列の多孔質材を示し、多孔質材(2) は、第２列目、多孔質材(3) は、第３列目（この場合は最後列）を示す。
空間(1) は、多孔質材(1) と多孔質材(2) との間の空間、空間(2) は、多孔質材(2) と多孔質材(3) との間の空間を示す。
【００２７】
【発明の効果】
以上に説明したように、本発明の吸音構造体及び吸音板は、表面側と中間部分と裏面側のアルミニウム系の金属多孔質材の面密度を前述のように変化させて配置することにより、幅広い周波数領域にわたって高い吸音性能を発揮でき、また長期間にわたり安定した吸音性能を維持することができる利点がある。
【図面の簡単な説明】
【図１】本発明の吸音構造体を示す模式的な断面図。
【図２】本発明の吸音構造体の他の構造を示す模式的な断面図。
【図３】吸音構造体の変形例を示す断面図。
【図４】吸音構造体の他の変形例を示す断面図。
【図５】吸音構造体の他の変形例を示す断面図。
【図６】本発明の吸音板を示す斜視図（Ａ）及び断面図（Ｂ）。
【図７】実施例の吸音特性図。
【符号の説明】
１、２、２１、２２ 金属多孔質材、３ 遮音材、４、４１、４２ 中間空気層、５ 背後空気層、６ 枠材、７ 支柱。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sound absorbing structure used for noise countermeasures such as a noise barrier for roads and railways and a tunnel moat, and a sound absorbing plate using the sound absorbing structure.
[0002]
[Prior art]
As a sound absorbing material used for noise countermeasures such as soundproof walls and tunnel moats, flat porous sound absorbing materials such as inorganic fiber sound absorbing material, metal fiber sound absorbing material, cement or calcium silicate foam sound absorbing material, ceramic sound absorbing material, etc. Is used. However, since these have a constant composition, porosity, air flow resistance, strength, etc., their sound absorption performance is also constant, and it is difficult to improve the sound absorption performance by changing the void structure and the like. In particular, rigid porous sound-absorbing materials such as metal fiber-based sound-absorbing materials are difficult to improve because of their peak sound absorption characteristics.
[0003]
[Problems to be solved by the invention]
The present invention has been made to solve the above-described conventional problems and provide a sound absorbing structure having a high sound absorbing performance over a wide frequency range and a sound absorbing plate using the sound absorbing structure.
[0004]
[Means for Solving the Problems]
The above problem is that the sound-absorbing structure of the present invention has three or more layers of an aluminum-based metal porous material arranged with an intermediate air layer between them, and a sound insulating material with a back air layer behind it. The sound absorbing structure is arranged, and the surface density of the metal porous material in the last row is larger than the surface density of the metal porous material in the front row in a ratio range of 1.1 to 10 , and is intermediate The surface density of the porous metal material arranged in the above is equal to or greater than the surface density of the metal porous material in the front row, and is smaller than the surface density of the metal porous material in the last row. This can be solved by a sound absorbing structure.
[0005]
Further, the metal porous material can be embodied in a form that is a porous material made of an aluminum-based metal fiber body, or in a form that is a porous material in which an aluminum-based metal fiber body and a metal perforating material are laminated. Furthermore, it is preferable that the surface density of the aluminum-based metal fiber body is 0.3 to 5.0 kg / m ² .
In addition to the above, the metal porous material can also be applied to a porous material in which aluminum-based metal particles are bonded, and a porous material made of an aluminum-based metal foam. A combination of two or more of these can also be applied.
[0006]
Furthermore, the above problem can be solved by the sound absorbing plate, wherein the sound absorbing structure of the various configurations Ward described previously, metal, that it has been assembled from cement or plastic frame member.
[0007]
The sound-absorbing structure of the present invention can exhibit high sound-absorbing performance over a wide frequency range by combining aluminum-based metal porous materials having different surface densities through a space. The reason is that sound absorption characteristics having peaks at different frequencies can be obtained by changing the thickness of the air layer behind the thin plate-like porous material, but the sound absorbing structure of the present invention is located at different positions from the sound insulating material. Since the metal porous materials are respectively arranged on the two, peaks appear at different frequencies, and the sound absorption characteristics as a whole are flattened. In addition, since the surface density of the front and rear metal porous materials is changed, there is an advantage that the sound absorption characteristics are further flattened as shown in the data of examples described later. Moreover, since the aluminum type metal porous material is used, it is excellent in weather resistance and corrosion resistance, and the sound absorption performance is not deteriorated over a long period of time.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing a first embodiment of a sound absorbing structure according to the present invention, wherein 1 is a metal porous material in the front-side front row, and 2 is a metal porous in the back row arranged inside. The material 3 is a sound insulating material further disposed behind it. 4 is an intermediate air layer formed between the metal porous material 1 on the surface and the metal porous material 2 in the rear row, and 5 is a rear surface formed between the metal porous material 2 in the rear row and the sound insulating material 3. It is an air layer.
In the present invention, these metal porous materials 1 and 2 are both aluminum-based, and the surface density thereof is about 0.3 to 5.0 kg / m ^{2 in} order to obtain preferable sound absorption characteristics. This is characterized in that the surface density of the metal porous material 2 is larger than that of the metal porous material 1 in the front row.
[0009]
When the surface density is changed in this way, the sound absorption coefficient peaks of the respective porous materials appear at different frequencies, the overall sound absorption characteristics are flattened, and high sound absorption characteristics can be obtained over a wide range of frequencies. Contrary to the present invention, when the surface density of the first row of porous metal materials 1 is made larger than the surface density of the second row of porous metal materials 2, the overall sound absorption characteristics are governed by the first row of porous metal materials 1. Therefore, the effect of the internal metal porous material 2 is not sufficiently exhibited. In the present invention, the ratio of the surface density of the metal porous material 2 in the rear row and the surface density of the metal porous material 1 in the front row is particularly preferably set to 1.1 to 10.
[0010]
In the case of FIG. 1 above, the metal porous materials 1 and 2 are arranged in two rows. However, in the present invention, three or more layers of metal porous materials are arranged. For example, as shown in FIG. The present invention is also applicable to a sound-absorbing structure in which the quality materials 1, 2, and 22 are arranged with the intermediate air layers 41 and 42 therebetween.
In this case, the surface density of the metal porous material 22 in the last row is made larger than the surface density of the metal porous material 1 in the front row, and the surface density of the metal porous material 21 arranged in the middle is It is important to obtain a preferable sound absorbing characteristic that the surface density of the metal porous material 1 in the front row is equal to or greater than the surface density of the metal porous material 1 in the front row and is smaller than the surface density of the metal porous material 1 in the last row. .
In this case as well, the sound insulating material 3 is disposed across the back air layer 5 as in the case of FIG.
[0011]
The size of the sound absorbing structure of the present invention is as follows.
First, the thickness of the entire sound absorbing structure is adjusted according to the frequency of the target sound source, but is set to about 50 to 200 mm in consideration of application to a general soundproof wall. When the target is low frequency sound, the entire thickness is increased, and when the target is high frequency sound, the entire thickness is decreased. It is preferable that the metal porous materials 1 and 2 or the metal porous materials 21 and 22 have a thickness of about 0.5 to 4 mm, and the intermediate air layer 4 and the back air layer 5 are both 10 mm or more. Outside these ranges, it becomes difficult to satisfy the sound absorption characteristics required of the soundproof wall.
[0012]
In the first embodiment, the metal porous materials 1, 2, 21, and 22 are made of aluminum-based metal fibers. Here, the aluminum system includes not only aluminum but also an aluminum alloy containing aluminum as a main component. The fiber diameter is preferably 20 to 200 μm, and the fiber length is preferably 10 mm or more. Such a metal fiber can be formed into a mat-like aggregate and used as it is, but preferably the metal fiber aggregate is pressure-formed by roll rolling, press rolling or the like to form a plate or pressure-formed. It is also preferable to use a metal fiber body in which the strength is increased by further applying or impregnating the material with an adhesive.
[0013]
In order to further increase the strength of such a metal fiber body, it is combined with a metal perforated material such as punching metal, metal net, and expanded metal having an opening ratio of 20 to 90% and a thickness of about 0.4 to 1 mm, It is preferable to protect the surface of one side or both sides. The metal perforated material as the protective material is also preferably an aluminum-based metal.
[0014]
In the present invention, the reason for limiting the numerical values is as follows. When the fiber diameter and the fiber length are smaller than the above values, the mechanical strength of the metal porous material 1, 2 or 21, 22 is reduced, or scattering due to wind or the like is increased. When the fiber diameter is larger than the above value, the sound absorbing performance is lowered. The porous metal materials 1 and 2 that fall within the above numerical range have an air flow resistance per unit area of 10 to 3000 N · sec / m ³ .
Further, if the aperture ratio of the metal perforated material is smaller than the above value, the sound absorbing performance is lowered, and conversely if it is larger than the above value, the mechanical strength of the metal porous materials 1 and 2 is lowered.
[0015]
In the second embodiment of the present invention, the metal porous materials 1, 2 or 21, 22 are made of a porous material in which aluminum-based metal particles are bonded. For this, a porous material in which aluminum-based metal particles (including powder) are sintered or bonded with an adhesive to form a large number of voids communicating with the front and back surfaces can be applied.
[0016]
In the third embodiment, the metal porous material 1, 2 or 21, 22 is a porous material made of an aluminum-based metal foam. This is a porous material in which aluminum-based metal is foamed to form a large number of cavities inside and a large number of voids communicating with the cavities. The porous metal materials 1 and 2 of the second and third embodiments also have a surface density of 0.3 to 5 kg / m ² and an air flow resistance per unit area of 10 to 3000 N · sec / m ^3. It is preferable that
[0017]
In the first to third embodiments, one kind of material that can be used for each of the metal porous materials is exemplified. However, as described in claim 8, the aluminum-based metal fibers described above are used. Or a combination of two or more selected from the group of an aluminum-based metal particle bonded body and an aluminum-based metal foam.
[0018]
In the present invention, as the sound insulating material 3 disposed behind the last row of the metal porous material 22, a material having sound transmission loss such as concrete, glass, plastic, etc. is used in addition to a metal such as an iron plate. Even a porous material having moderate sound transmission loss can be used as the sound insulating material 3 of the present invention.
[0019]
In addition to the basic cross-sectional shape shown in FIGS. 1 and 2, the sound-absorbing structure of the present invention includes two layers of porous metal materials 1, 2 and three layers of porous metal material as shown in FIG. The shape and arrangement of 1, 2, 22 can also be changed variously. Further, as shown in FIG. 4, the cross section may be triangular or semicircular. Furthermore, as shown in FIG. 5, it can also be set as a circular cross-sectional shape. In the case of FIG. 5, there is an advantage that a sound absorption effect can be expected for sound from any direction. Moreover, in this invention, although not shown in figure, it cannot be overemphasized that it can materialize in a 4 layer metal porous material.
In the sound absorbing structure of the present invention, a material or a film having a through hole such as a perforated plate or a net is disposed on the surface or the air layer portion within a range not significantly impairing the sound absorbing characteristics, or the air layer portion is disposed on the air layer portion. A porous material having a communicating hole such as a fibrous material or a granular material may be inserted and filled.
[0020]
Next, the sound absorbing plate of the present invention will be described.
As illustrated in FIG. 6, the sound absorbing plate of the present invention is a panel formed by assembling any of the above sound absorbing structures inside the frame member 6. FIG. 6 shows an example in which the metal metal porous materials 1 and 2 and the sound insulating material 3 are assembled to the frame material 6. The material of the frame material 6 is the same as that of conventional materials such as metal, cement, and plastic. can do.
[0021]
In addition, when installing the sound absorbing plate in FIG. 6 on the tunnel, the wall surface of the moat, the ceiling surface, or the back surface of the elevated, the sound insulating material overlaps because the wall surface is a sound insulating material such as concrete. The sound insulating material toward the sound absorbing plate may be omitted. On the other hand, the sound absorbing plate with the sound insulating material 3 as shown in FIG. 6 can be used as a sound absorbing sound insulating plate for a soundproof wall. In this case, a soundproof wall or the like is formed by dropping between the H-shaped columns. The anchor bolts are placed on the concrete wall surface at predetermined intervals on the tunnel, the wall of the moat, and the ceiling surface, and fixed by using a mounting bracket. It is attached to the underside of the elevated by a method of fixing with bolts to the foundation such as a receiving beam.
[0022]
【Example】
A mat-shaped metal fiber body in which aluminum fibers having a fiber diameter of 20 to 200 μm and a fiber length of 10 mm or more are assembled, an aluminum expanded metal, and an aluminum punching metal are used in Table 1, using an acrylic resin adhesive. A flat plate-shaped porous material having a surface size of 500 × 2000 mm having various physical properties shown was prepared.
A to D and F to I in the table adjust the fiber amount so as to have a predetermined areal density, prepare a laminated mat-like aluminum fiber body, and apply aluminum expanded metal and punching metal on one or both sides thereof. A porous material was created by placing and roll rolling. G was prepared by roll rolling and then impregnating an acrylic resin adhesive to the inside so as not to clog the voids, and then curing.
E was prepared by roll-rolling a mat-like aluminum fiber body having a predetermined surface density as it was, then impregnating an acrylic resin with an adhesive to the inside so as not to clog the voids, and then curing.
[0023]
The various porous materials obtained in this manner are arranged under the conditions shown in Table 2 to create sound absorbing structures, and each sound absorbing structure is made to enter the test body perpendicularly using a pulsed sound source to absorb the sound absorption rate. It measured by the method of measuring. In this table, the arithmetic average sound absorption coefficient at a frequency of 400 to 4000 Hz was obtained and described. The sound insulating material was a galvanized iron plate, which was common to each test specimen.
Moreover, about test body No4, No14, No21, No24, the characteristic of the frequency-sound absorption rate in the frequency of 100-4000 Hz was shown in FIG.
In the table, test bodies No1 to No20 are examples of the present invention, and test bodies No21 to No26 are comparative examples not included in the technical scope of the present invention.
[0024]
According to this result, it turns out that test body No1-12 of this invention shows a high sound absorption coefficient over a wide frequency, and also shows a high value for the average sound absorption coefficient of 400-4000 Hz. In addition, the sound absorption characteristics of the specimens Nos. 25 to 26 in which only one porous material is arranged have a peak property that the sound absorption coefficient in a specific frequency range is high, and the average sound absorption coefficient of 400 to 4000 Hz is also No. 1 of the present invention. Lower than ~ 20. In addition, it can also be understood that the sound absorption characteristics of the test bodies No. 21 to No. 23 outside the scope of the present invention also have a peak sound absorption characteristic, and the average sound absorption rate of 400 to 4000 Hz is lower than that of Nos. 1 to 20 of the present invention.
[0025]
[Table 1]

Note: EM is an abbreviation for expanded metal and PM is an abbreviation for punching metal.
[0026]
[Table 2]

Note: Porous material (1) indicates the front row of porous material, porous material (2) is in the second row, porous material (3) is in the third row (in this case the last row) ).
Space (1) is the space between porous material (1) and porous material (2), and space (2) is the space between porous material (2) and porous material (3). Show.
[0027]
【The invention's effect】
As described above, the sound absorbing structure and the sound absorbing plate of the present invention are arranged by changing the surface density of the aluminum-based metal porous material on the front surface side, the intermediate portion, and the back surface side as described above, There is an advantage that high sound absorption performance can be exhibited over a wide frequency range, and stable sound absorption performance can be maintained over a long period of time.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a sound absorbing structure of the present invention.
FIG. 2 is a schematic cross-sectional view showing another structure of the sound absorbing structure of the present invention.
FIG. 3 is a cross-sectional view showing a modification of the sound absorbing structure.
FIG. 4 is a cross-sectional view showing another modification of the sound absorbing structure.
FIG. 5 is a cross-sectional view showing another modification of the sound absorbing structure.
FIG. 6 is a perspective view (A) and a cross-sectional view (B) showing a sound absorbing plate of the present invention.
FIG. 7 is a sound absorption characteristic diagram of the example.
[Explanation of symbols]
1, 2, 21, 22 Metal porous material, 3 Sound insulation material, 4, 41, 42 Intermediate air layer, 5 Back air layer, 6 Frame material, 7 Prop.

Claims (8)

A sound-absorbing structure in which three or more layers of an aluminum-based metal porous material are disposed with an intermediate air layer therebetween and a sound insulating material is disposed behind the intermediate air layer, and the metal porous material in the last row The surface density of the metal porous material arranged in the middle is made larger in the range of the ratio of 1.1 to 10 with respect to the surface density of the metal porous material in the front row, and the surface density of the metal porous material arranged in the middle A sound-absorbing structure characterized by being equal to or greater than the surface density of the material and smaller than the surface density of the metal porous material in the last row . The sound absorbing structure according to claim 1, wherein the metal porous material is a porous material made of an aluminum-based metal fiber body. The sound absorbing structure according to claim 1, wherein the metal porous material is a porous material in which an aluminum-based metal fiber body and a metal perforating material are laminated. The sound absorbing structure according to claim 2 or 3 , wherein the aluminum-based metal fiber body has a surface density of 0.3 to 5.0 kg / m2. The sound absorbing structure according to claim 1, wherein the metal porous material is a porous material in which aluminum metal particles are bonded. The sound absorbing structure according to claim 1, wherein the metal porous material is a porous material made of an aluminum-based metal foam. The sound absorbing structure according to claim 1 or 2, wherein the metal porous material is a combination of two or more porous materials according to claims 2 , 3 , 5, and 6 . And sound absorbing structure according to any one of claims 1 to 7 metal, the sound absorbing plate, wherein assembled from cement or plastic frame member.

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