JPH0347348A - Composite sound-absorbing wall materials and composite sound-absorbing wall structures - Google Patents

Abstract

PURPOSE:To improve sound absorbing efficiency in frequency range extending over a wide scope by attaching a composite sound-absorbing wall material made of a sound-absorbing material having resonant sound-absorbing mechanism and a sound-absorbing material having frictional sound-absorbing mechanism in lamination to a wall main body with an air layer kept behind the material. CONSTITUTION:A foamed aluminum sound-absorbing material 1 having resonant sound-absorbing mechanism and a porous sound-absorbing material 2 having frictional sound-absorbing mechanism are put together in lamination and a composite sound-absorbing wall material W is constructed therewith. Then the composite sound-absorbing wall material W is attached to a sound-absorbing wall main body 4 with a specified hinder air layer 3 kept in between. Thereby highly efficient sound absorbing function can be developed in any of frequency ranges from low-to-middle pitched to high-pitched sound and, at the same time, rate of utilization for available space can be improved while the cost is reduced.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a composite sound-absorbing wall material and a composite sound-absorbing wall structure, and in particular, to a composite sound-absorbing wall material and a composite sound-absorbing wall structure, in which a plurality of sound-absorbing materials having different sound absorption coefficient frequency characteristics are laminated,
This is a complementary improvement of their sound absorption coefficient frequency characteristics.

(Prior art) Foamed aluminum is an aggregate of air bubbles made of a thin aluminum film, and each air bubble forms the most three-dimensionally stable polyhedron, so it has excellent sound-absorbing and sound-insulating effects. In addition to being a functional material, it is known to have high processability such as cutting, drilling, bending, etc., and adhesive properties, and is used as a sound absorbing or soundproofing material in factories, roads, railways, acoustic rooms, and other places. .

Sound absorbing or sound insulating materials used for the above-mentioned purposes are known to have a structure in which thin metal plates such as aluminum, copper, titanium, etc. are bonded to the front and back surfaces of foamed aluminum.

In an example where aluminum foam sound absorbing material is applied to a sound absorption wall, the frequency at which the sound absorption coefficient is maximum decreases as the thickness of the back air layer increases, so a large back air layer is required to obtain a high sound absorption coefficient in the low frequency range. becomes. Even when a porous sound-absorbing material is applied to the sound-absorbing wall, it is necessary to increase the thickness of the rear air layer and the thickness of the sound-absorbing material in order to obtain a high sound absorption coefficient in the low frequency range.

Conventionally, the above-mentioned foamed aluminum sound-absorbing material or porous sound-absorbing material has been used alone as a sound-absorbing material for a sound-proof wall (sound-absorbing wall). In this case, in order to obtain a sound absorption coefficient of 70χ near 250112 in the low frequency range, as shown in the graph of sound absorption coefficient by the reverberation room method shown in Figure 9, the maximum sound absorption coefficient frequency (however, It was important to adjust the maximum sound absorption coefficient frequency f1 (refers to the frequency at which the maximum sound absorption coefficient of the first peak P shown in the sound absorption curve of FIG. 10A) to 500H2 or less.

That is, as is clear from the graph showing the relationship between the maximum sound absorption coefficient frequency Lm□ and the back air layer thickness in FIG. 10B, 40
751 for aluminum foam sound absorbing material at 0hz frequency
1L11, which is about the same thickness as the entire conventional soundproof wall (solid line graph), but in the case of cloth-like porous sound absorbing material, it is 150111! I or more (dotted line graph), which indicates that a large back air layer is required. In addition, the sound absorption coefficient of aluminum foam sound absorbing material is sufficiently high in the mid-to-high frequency range (although in the case of cloth-like porous sound absorbing material, even if the back air layer is increased and the sound absorption curve is shifted to the lower frequency side, the sound absorption coefficient is not high enough). The drop in sound absorption coefficient in this region is slight.

As mentioned above, foamed aluminum sound absorbing materials and cloth-like porous sound absorbing materials have been used individually as materials applied as sound absorbing wall materials for sound absorbing walls, but the actual situation is as described above. .

(Problems to be Solved by the Invention) As mentioned above, aluminum foam sound absorbers and cloth-like porous sound absorbers have been applied individually to sound absorbing walls. If the material is applied alone to a sound-absorbing wall, the above objective will be achieved in the low-frequency range, but the desired sound-absorption coefficient will not be achieved in the mid-to-high frequency range.

Furthermore, when a cloth-like porous sound-absorbing material is applied alone to a sound-absorbing wall, the desired sound absorption coefficient cannot be obtained unless the rear air layer is enlarged, and as a result, the overall size of the sound-absorbing wall increases. For this reason, the installed indoor effective space becomes narrow, and when this is applied to a soundproof wall for roads, etc., the space usable area becomes larger and the construction cost increases.

In summary, when conventional aluminum foam sound absorbing materials and cloth-like porous sound absorbing materials are applied alone to sound absorbing walls, high sound absorption coefficients cannot be obtained for both mid-high and low sounds.
In addition, the space occupancy rate is high (and the construction cost is also rising, which is not good).

The present invention was invented in view of the above points,
To provide a composite sound-absorbing wall material and a composite sound-absorbing wall structure which have a high sound absorption coefficient for both medium-high and low-frequency sounds, have a high effective space utilization rate, and can reduce construction costs.

(Means for Solving the Problems) As a means for solving the above-mentioned problems, the present invention is a method of polymerizing a foamed aluminum sound absorbing material having a resonance type sound absorption mechanism and a porous sound absorbing material having an N friction type sound absorption mechanism in a laminated state. A composite sound-absorbing wall material having such a structure, a foamed aluminum sound-absorbing material having a resonance type sound-absorbing mechanism, and a porous sound-absorbing material having a friction-type sound absorbing mechanism are laminated to form a composite sound-absorbing wall material, and this composite sound-absorbing wall material is A composite sound-absorbing wall structure is adopted in which the sound-absorbing wall is attached with a predetermined air space behind the wall body.

(Function) As in the present invention, a composite sound-absorbing wall material in which a foamed aluminum sound-absorbing material having a resonance-type sound-absorbing mechanism and a porous sound-absorbing material having a friction-type sound-absorbing mechanism are polymerized in a laminated state is provided with a predetermined front and rear air layer. As a result of adopting a configuration in which the sound absorbing wall was attached to the main body, a high sound absorption coefficient as shown by curve A in FIG. 9 was obtained.

That is, as shown in curve A in the graph of FIG.
What can be seen as a characteristic is that a high sound absorption coefficient can be obtained over a wide frequency range.
0) It was confirmed that the sound absorption coefficient was 80% or more (back air layer 35I) in the range of IZ to 5KllZ. Second
The characteristics of maximum sound absorption coefficient frequency f01. If we look at the case where a foamed aluminum sound absorbing material or a porous sound absorbing material is used alone as a sound absorbing wall (back air layer 35 mm) and the sound absorbing wall material of the present invention, the maximum sound absorption coefficient frequency fmax of the sound absorbing wall material of the present invention is , approximately 173~ compared to when foamed aluminum sound absorbing material is used alone (same song &'1lB)
The frequency is shifted by 1/4 octave to the lower frequency side, and is only about 2 to 3/2 octaves compared to when a fiber porous sound absorbing material with a friction type sound absorption mechanism is used alone (curve C in the same figure). It can be seen that the frequency has shifted to the lower frequency side.

As a third characteristic, as shown in the figure, the maximum sound absorption coefficient of the present invention is higher than that when the above-mentioned sound absorption material is used alone.

The sound absorption coefficient, maximum sound absorption coefficient frequency, and maximum sound absorption coefficient have the characteristics as described above.

Next, the thickness of the back air layer is around 401, 30e
The optimal range is from +m to 50mm, and when it is less than 30us, a sound absorption wall with a composite structure of foamed aluminum sound absorbing material and cloth-like porous sound absorbing material will have a sound absorbing wall of 70% near 25011Z.
This is because it is not possible to obtain a maximum sound absorption coefficient of more than 50IIl111, and the limitation is due to the physical reason that if the thickness of the wall that is normally used is 5mm or more, the wall becomes thick.

Incidentally, if we compare the case where a conventional sound absorbing material is used alone and the case of the present invention, it is found that if the sound absorption coefficient is to be the same as that of the low frequency side region (500112) in curve A in Fig. 9, the rear air It is necessary to adjust the layer thickness. That is, in the case of foamed aluminum sound absorbing material, the back air layer 75 is similar to the curve iD, and a cloth-like porous material (glass cloth;
In the case of a thickness of 1.6m+m), the characteristic of curve E is obtained, and the thickness of the rear air layer at that time is as thick as 15hs.

The reason why the aluminum foam sound absorbing material is thin in terms of the thickness of the back air layer in the low frequency range is that when the maximum sound absorption coefficient frequency of the foam aluminum sound absorbing material is the same as the back air layer, when compared with other sound absorbing materials, This is due to the fact that the noise level is much lower than that of sound absorbing materials. Furthermore, the sound absorption coefficient of the aluminum foam sound absorbing material increases by a maximum of about 30x in the medium and high frequency range, and this is due to the presence of the cloth-like porous sound absorbing material placed behind the foam aluminum sound absorbing material. The reason for this is that the sound absorption coefficients of foamed aluminum sound-absorbing material and cloth-like porous sound-absorbing material act in an additive manner, and their effects appear in a complementary manner in the low and mid-to-high sound ranges, compared to conventional sound-absorbing walls. 1/3~ compared to the thickness
A high sound absorption coefficient was obtained over the entire area with a thickness of 1/2.

(Example) Examples of the composite sound-absorbing wall material and composite sound-absorbing wall structure of the present invention will be described in detail below with reference to FIGS. 1 to 8.

Star↓l螤■ To explain the first embodiment, which is the basic structure of the present invention, with reference to Fig. 1, reference numeral (1) is a foamed aluminum sound absorbing material, which is made of air bubbles made of a thin aluminum film. The aggregate is connected to form a breathable porous body, which has sound absorption properties such as conversion of sound energy into heat due to frictional resistance with the membrane surface, interference properties due to diffuse reflection of incident sound on the membrane surface of bubbles, and internal air layer. By selecting the thickness, etc., it has excellent sound absorption characteristics over a wide range of frequencies.

Code (2) is a cloth-like porous sound absorbing material, specifically glass cloth, cotton cloth, nonwoven fabric, etc., and the thickness is 0.
．． 8s weight, areal density 240g/m"~2000g/s"
It is molded as. When the foamed aluminum sound-absorbing material (1) and the cloth-like porous sound-absorbing material (2) are joined together on their entire interface with an adhesive network, the cloth-like porous sound-absorbing material (2) becomes Based on the understanding that it is difficult to absorb sound energy due to membrane vibration of the sound absorbing material (2), this example uses a foamed aluminum sound absorbing material (1) and a fabric-like porous sound absorbing material (2) as shown in the figure. Attach by appropriate means.

As described above, the composite sound-absorbing wall material W is constructed by laminating and polymerizing the foamed aluminum sound-absorbing material (+1) and the cloth-like porous sound-absorbing material (2).

Reference numeral (4) is a steel wall that becomes the composite sound-absorbing wall body to which the composite sound-absorbing wall material W is attached, and a wall base material (5) is interposed between this steel wall (4) and the composite sound-absorbing wall material W. 30 cranes made by...
A composite sound absorbing wall structure with a back air layer (3) of 50 m5 is constructed.

The basic structure of the composite sound-absorbing wall structure of the present invention is as described above. ) (6) is 1OOOOHz if there is a large slack between the two or an intermediate air layer X as shown in Figure 2.
Since the sound absorption characteristics in the medium and high frequency range of ~400011Z deteriorate significantly, the structure is constructed so that the slack and the intermediate air layer X are theoretically zero.

In other words, the reason why the sound absorption characteristics drop significantly in the middle and high frequency range is that, as is clear from the graph showing the relationship between the frequency 112 and the sound absorption coefficient α in Fig. 3, the curve a when the intermediate air layer x = 00 and the intermediate air 1x =x.

Amount of drop in sound absorption coefficient Δ in the middle and high frequency range of the curved line in the case of
α increases in proportion to the thickness of the intermediate air layer X. Note that the curve C in the same figure is a curve showing the sound absorption characteristics when the foamed aluminum sound absorbing material is used alone, and is shown as a comparative example.

As mentioned above, regarding the intermediate air layer The amount of fall Δα of α is zero, and the intermediate air layer X=X, (
10-30Il11), it increases gradually.

Therefore, if the thickness of the intermediate air Nx at the joint between the aluminum foam sound absorbing material (1) and the cloth-like porous sound absorbing material (2) is theoretically set to zero, the drop point Δα of the sound absorption coefficient α in the mid-to-high sound range is the minimum.

A second embodiment of the present invention will be described in detail based on a cross-sectional view of the main part of No. J01 in FIG.

In the example shown in the figure, a composite sound-absorbing wall material W is formed by applying a foamed aluminum sound-absorbing material (1) and glass cloth as a cloth-like porous sound-absorbing material (2), and this is applied to a composite sound-absorbing wall. This is an example.

That is, as shown in the same figure, a foamed aluminum sound absorbing material (1) with a thickness of 10 III is laminated with glass cloth (2) with a thickness of 1, f) + 111 to form a composite sound absorbing wall material W. Rip as a 35mm wall base material (41)
Although not shown, they are attached to concrete plates (4) formed at appropriate intervals using fasteners such as bolts to form a composite sound-absorbing wall structure. Note that the space between the concrete plate (4) and the grass cloth (2) becomes the back air N (3).

The configuration of the second embodiment is as described above. The sound absorption coefficient α when each of the foamed aluminum sound absorbing material (1) and the cloth-like porous sound absorbing material (2) are used alone as the M joint sound absorbing wall material W is calculated from the rear air layer (3).
A comparative experiment was conducted using 351Il and other conditions under the same conditions, and the results shown in the graph of FIG. 6 were obtained.

The graph in Figure 6 shows the relationship between frequency and reverberant house method sound absorption coefficient α, and the composite sound-absorbing wall material of this example is shown as A, the aluminum foam sound-absorbing material alone as B, and the glass cloth alone as C. .

According to the results of the graph, the sound absorption coefficient α of the composite sound-absorbing wall material A of this example is higher than the characteristic curve B for the foamed aluminum sound-absorbing material alone and the characteristic curve C for the glass cloth alone (2). The maximum sound absorption coefficient frequency ferax is shifted to the lower frequency side by about 1/3 octave, which results in a lower frequency range (
25011z) was improved to 74χ, an improvement of up to 43% compared to curve B when foamed aluminum sound absorbing material was used alone. Also, high frequency range (2500H
2) also showed an improvement of up to 25χ compared to the sound absorption coefficient α when the foamed aluminum sound absorbing material was used alone.

Furthermore, 100011z to 4000H2Iii (7)
The average sound absorption coefficient α was found to be a high value of 90.9±3.9χ. Regarding the structure, in the case of this example, the distance from the concrete plate (4) is 46.6 mm.
The thickness was similar to that of commonly constructed indoor decorative walls.

A third embodiment of the present invention will be described in detail based on the main part sectional view of the n01th doctor FIG.

In the example shown in the figure, a composite sound-absorbing wall material W is formed by polymerizing a foamed aluminum sound-absorbing material (1) and felt as a cloth-like porous sound-absorbing material (2), and a predetermined air layer is provided behind the material. This is an example of a composite sound-absorbing wall structure by attaching it to a concrete plate (4). That is, as shown in the figure, a composite sound-absorbing wall material W is formed by laminating and polymerizing a foamed aluminum sound-absorbing material (1) with a thickness of 10IIIm and a felt (2) with a thickness of 6 chains. A rear air layer (3) is provided and attached to the concrete plate (4) using fasteners such as bolts (not shown),
Compose a composite sound-absorbing wall.

The structure of the third embodiment is as described above, and the composite sound-absorbing wall material W of this embodiment and the foamed aluminum sound-absorbing material (11) and the cloth-like porous sound-absorbing material (2) are used as the composite sound-absorbing wall material W. When the sound absorption coefficient α when used alone was compared with the rear air layer (3) of 40 m1 and other conditions were the same, the results shown in the graph of FIG. 8 were obtained.

The graph in FIG. 8 shows the relationship between frequency and reverberation sound absorption coefficient α, and the composite sound-absorbing wall material of this example is designated as A, the aluminum foam sound-absorbing material alone is designated as B, and the glass cloth alone is designated as C.

According to the results of the same graph, the sound absorption coefficient α of the composite sound-absorbing wall material W of this example is the maximum sound absorption coefficient frequency f in the case of the foamed aluminum lining sound-absorbing material alone. , lower frequency range than X (2501
12) has been improved to 70χ, and the sound absorption coefficient α in the high frequency range (2
500Hz), a significant improvement was also seen in the sound absorption coefficient α compared to the case of using the foamed aluminum sound absorbing material alone.

Furthermore, the average sound absorption coefficient α between 100OH2 and 400011Z is 85±4. High values of Oz were observed.

In terms of structure, in the case of this example, the distance from the concrete plate (4) was 51.6 ms+, which was almost the same as the thickness of a commonly constructed indoor decorative wall.

(Effects of the Invention) According to the composite sound-absorbing wall material and composite sound-absorbing wall structure of the present invention, the first characteristic is that a high sound absorption coefficient can be obtained over a wide range of 111 wave numbers, and the second characteristic is that a high sound absorption coefficient can be obtained over a wide range of 111 wave numbers. The maximum sound absorption coefficient frequency is approximately 173 when using aluminum foam sound absorbing material alone as a sound absorbing wall compared to when foam aluminum sound absorbing material or porous sound absorbing material is used alone as a sound absorbing wall.
The frequency is shifted to the lower frequency side by ~1/4 octave, and by about 2 to 3/2 octaves compared to when a porous sound absorbing material with a frictional sound absorbing mechanism is used alone (curve C in the same figure). The third characteristic is that the maximum sound absorption coefficient is a higher value than when the above sound absorbing material is used alone, the maximum sound absorption coefficient frequency, and the maximum sound absorption coefficient. A pond that has good characteristics regardless of its sound absorption coefficient.
It has the advantage that the space occupancy rate of the wall itself is low and the construction cost is low.

4. Brief explanation of the Iil'Q plane FIG. 1 is a cross-sectional view of the main part showing the basic structure of the composite sound-absorbing wall of the present invention, FIG. 2 is a cross-sectional view of the main part showing another embodiment of the present invention, and FIG. The figure is a graph showing the relationship between the frequency H2 and the sound absorption coefficient α, FIG. 4 is a graph showing the relationship between the drop in the sound absorption coefficient Δα and the thickness of the intermediate air layer X, and FIG. 5 is another embodiment of the present invention. 6 is a graph showing the relationship between the frequency and the reverberation sound absorption coefficient α in the embodiment of FIG. 5, and FIG. 7 is a sectional view of the main part showing another embodiment of the present invention. Figure 8 is a graph showing the relationship between frequency and reverberation method sound absorption coefficient α in the example of the seventh threshold, Figure 9 is a graph of sound absorption coefficient by the typical reverberation room method, and Figure 1A is the maximum sound absorption coefficient. A graph showing the frequency, FIG. 1B, is the maximum sound absorption coefficient frequency f am. It is a graph which shows the relationship between and the back air layer thickness.

The names of the codes are as follows.

(1) - Foamed aluminum sound absorbing material, (2) - Cloth-like porous sound absorbing material, (3) - Back air layer, (4) - Composite sound absorbing wall body, (5) Sound absorbing wall base material, W -・Composite sound-absorbing wall materials, Figures 1 and 2, Figure 3

Claims (2)

[Claims] (1) A composite sound-absorbing wall material characterized by a laminated polymerization of a foamed aluminum sound-absorbing material having a resonance-type sound-absorbing mechanism and a porous sound-absorbing material having a friction-type sound-absorbing mechanism. (2) Form a composite sound-absorbing wall material by laminating a foamed aluminum sound-absorbing material with a resonance-type sound-absorbing mechanism and a porous sound-absorbing material with a friction-type sound-absorbing mechanism, and combine this composite sound-absorbing wall material with a sound-absorbing wall body. A composite sound-absorbing wall structure with a predetermined back air space between the walls.