JPH0447838B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sound insulation structure having an acoustically multi-walled structure with improved sound insulation performance.

In recent years, in order to deal with problems such as residential noise, research and development of many sound insulation technologies and materials have been carried out. In addition, building materials are required to have higher performance. That is, insulation, weight reduction, and non-combustibility are required from the viewpoints of saving resources, energy, and improving safety, and thinning is required from the viewpoint of expanding space and improving workability. For this reason, sound insulating materials and sound insulating structures that meet these requirements are now required. However, improving the sound insulation performance of building materials or buildings and the above-mentioned required performance are often in conflict with each other, and it has been difficult to achieve both.

In general, the sound insulation performance of sound insulation materials is roughly determined based on the mass law for sound transmission, and the sound transmission loss (transmission loss), which indicates the sound insulation performance, is generally determined based on the mass law for sound transmission.
Loss (hereinafter referred to as TL) improves as the areal density increases. Furthermore, in order to improve the TL beyond the mass law, it is common to use a double-wall or multi-wall structure in which sound-insulating materials are arranged in parallel, and to further improve the sound-insulating effect by inserting a sound-absorbing material or the like inside. However, such a method inevitably results in an increase in weight and thickness. In addition, a particular problem is that even when such a method is used, a significant decrease in TL, that is, a sound insulation defect, often occurs in a specific sound range due to the coincidence effect, resonance transmission in the low range, and the like. A common method to improve this sound insulation deficit is to change the natural frequency due to the sound insulation material and structure in order to move the frequency range that causes the sound insulation deficit out of the audible range, which is also difficult to do with traditional methods. This tends to cause problems such as an increase in weight and thickness, or a decrease in the rigidity of the sound insulating material.

As mentioned above, in order to achieve high sound insulation,
The biggest challenge is how to achieve sound insulation that exceeds the mass law and how to prevent deterioration due to sound insulation defects. Currently, double walls and multiple walls are constructed using surface materials with relatively high surface density (including structural walls such as board materials).
Either insert a sound-absorbing material such as glass wool or rock wool inside and increase the overall TL while leaving insufficient countermeasures for the sound insulation loss, or replace the sound insulation loss within the audible frequency range (e.g. 125 ~
4000Hz), they are often designed and constructed without considering the significant increase in thickness and weight. Other countermeasures against sound insulation defects include inserting high-performance sound absorbing materials and applying vibration damping treatment to face materials, but these are expensive and often do not have sufficient effects.

The present invention realizes a method of suppressing the deterioration of sound insulation performance due to sound insulation defects as much as possible, and not only realizes the maximum sound insulation performance that can be obtained by the mass law in almost the entire audible frequency range. , which maximizes the increase in TL due to multi-wall construction.

The present inventor has discovered that when a sound insulation structure is constructed from area portions in multiple regions with different areal densities and natural frequencies in the sound insulation direction, the sound transmission loss decreases due to the coincidence effect, and the transmission loss due to resonance transmission at low frequencies decreases. It was discovered that the depression was significantly improved, and the present invention was completed.

The above phenomenon occurs when sound is almost uniformly incident on the entire surface of a structure, evenly or completely randomly, and despite receiving uniform air vibration, the areal density of the plate materials constituting the structure, Each part with a different natural frequency exhibits different acoustic behavior, and as a result, the transmitted sound components from each part are moderately different, so the synthesized sound after transmission is adjusted to eliminate harmful transmitted sound, In other words, it is thought that the sound in a specific frequency range is reduced due to sound insulation defects.

The sound insulation structure according to the present invention has an acoustically multi-wall structure, and the plate material constituting the structure is composed of a plurality of regions having different areal densities m, and the plurality of regions are arranged in each region. The ratio of the maximum value to the minimum value of the average areal density of is 1.2 or more, and the sum of the areas of the larger area and the smaller area of the areas that differ by 1.2 or more is 25% of the total area of the plate material. % or more, and the structure has a plurality of structural regions having different natural frequencies in a direction perpendicular to sound transmission, and the natural vibration of each of the plurality of structural regions is A region where r is large in a region where the ratio of the maximum value to the minimum value of the number r is 1.1 or more and the ratio of r is different by 1.1 or more,
The sum of the cross-sectional areas in the vertical cross-section perpendicular to the sound transmission direction of each small region of r is 25% or more of the total cross-sectional area in the vertical cross-section of the structure, and the r is large in the vertical cross-section. The structure is characterized in that the average diameter of the maximum circle included in each of the region where r is small and the region where r is small is larger than the thickness of the structure.

In other words, the structure is composed of multiple regions with different natural frequencies, and the areal density m of the plate materials is varied so that each region exhibits different acoustic behavior from the others, and the level of transmitted sound due to sound insulation defects is suppressed. Therefore, by appropriately separating the sound insulation deficit frequencies of each part of the area and reducing the transmitted energy to a level corresponding to the area of each part, the sound insulation deficit can be dispersed and leveled.

TL due to coincidence effect in sound insulation defects
T due to the drop in the pitch and resonance transmission in the bass range.
The decline in L. is a particular problem. In order to solve these problems, we studied the conditions of the plate materials and structures that make up the structure, and arrived at the present invention.

First, the plate material is composed of a plurality of regions having different areal densities m. This is because by varying the areal densities of each region, it is possible to appropriately disperse and equalize the sound insulation loss frequencies in each part of the region. Therefore, the natural frequency of the panel is as follows:
You should mainly consider rmd. This is because countermeasures against rmd exhibit similar effects for other higher-order natural frequencies.

Further, the coincidence limit frequency c is expressed by the following equation.

c = (c ² / 2π) x (m/B) ^1/2 (where c is the speed of sound, m is the areal density, and B is the bending rigidity) In order to improve the sound insulation deficiency near this c by leveling or dispersing it. It is necessary that the ratio between the maximum value and the minimum value of c of the plate material in each region differs by at least 1.1. That is, assuming that the bending rigidity of the plate material is equal in each region, the areal density ratio needs to be 1.2 or more from the above equation. Therefore, it is necessary to set the ratio of the maximum value to the minimum value of the average areal density of each region to be 1.2 or more. This is because if this ratio is less than 1.2, the effect of dispersing and leveling TL in the coincidence limit frequency region becomes poor.

Next, the sum of the areas of the large area and the small area of the areas where the average areal densities differ by 1.2 or more is 25 of the total area of the board.
% or more, preferably 40% or more. This is because if each is less than 25%, even if it has a surface density that increases the TL by the mass law, the effects of dispersion and leveling in the coincidence limit frequency region described above cannot be obtained.

Although the sound insulation structure according to the present invention is formed using a plate material that satisfies the above conditions, the structure also needs to satisfy certain conditions. That is, the structure is configured to have a plurality of structural regions having different natural frequencies in a plane perpendicular to the sound transmission direction by using a plate material having the non-homogenized region. It is necessary that the ratio between the maximum value and the minimum value of the natural frequency r of each of the plurality of structural regions is 1.1 or more. This is because unless the ratio of natural frequencies is separated by 1.1 or more, the TL for each 1/3 octave band is
This is because it is hardly possible to level out the curve, and therefore it is impossible to improve sound insulation defects.

Next, in order to equalize or disperse sound insulation defects caused by resonance transmission in the low frequency range, for example, if the structure is a double wall, the resonance transmission frequency in the low frequency range must be
rmd is rmd=(1/2π)×[(1/m+1/m')
×(pc ² /d)] ^1/2 . However, m and m' are the areal density of each plate,
p is the density inside the structure (if a breathable material is used, it can be considered as air), c is the speed of sound, and d is the thickness inside the structure. The above c and rmd can be calculated as a part of the rigid body per unit width for each area. In addition, in order to exhibit acoustic behavior that meets the purpose of the present invention, 1.1 of the above rmd is required.
Each region exhibiting a large value (rmd ⁺ ) and a small value (rmd ⁻ ) of rmd with different values has a minimum required area. This area is referred to as a critical area, and this critical area differs depending on the type of plate material and the structure of the structure. For example, if the rigidity of the plate is small or the thickness of the structure is small,
The critical area is also generally smaller.

However, regardless of the type of plate material or the structure of the structure, in the present invention, rmd ⁺ and
It is necessary that the sum of the areas of the regions having rmd ^- above the critical area each account for 25% or more of the total area of the entire structure. If it is less than 25%, the effect will be poor, so it is preferable that it accounts for 40% or more. With this measure, improvements such as leveling can be made for each higher-order r at the same time. In other words, as mentioned above, rmd is
is the resonant transmission frequency in the bass range of r,
This is because an improvement in rmd immediately results in an improvement in r. Note that it is even more effective to use a structure that spatially partitions the inside of the plate materials, and in this case, it is desirable to install the partitions at the boundaries where the surface densities of the plate parts differ. Further, it is more advantageous that the rigidity of the plate portion is smaller.

Even if the area occupied by a single region of the rmd ⁺ or rmd ^- is larger than the critical area, its acoustic behavior is governed by the shape of the region, and in a cross section perpendicular to the direction of sound passage through the structure, the area occupied by the region is larger than the critical area. It is inappropriate if the cross-sectional shape is, for example, a picture frame shape or a comb blade shape. The critical area that takes this shape into consideration is the maximum circle included in the cross-sectional area in the vertical cross section, that is, the area that touches the contour surrounded by straight lines and curves at two or more points, and the total area is within the area. It turns out that it is best to represent it with the largest circle included. Assuming that the diameter of the maximum enclosed circle is dm, as a result of experiments with various shapes, it is necessary that dm be larger than the thickness of the sound insulation structure.
If the structure is a rigid material, dm is preferably three times the thickness or more. This is because if dm is smaller than the thickness of the structure, the effects of dispersion and leveling in the resonance transmission frequency region of the bass range described above will be poor. In addition, as a sound insulation structure,
There is a limit to the size due to manufacturing, construction, etc., so it is practical to limit the DM to 3 m or less.

Note that if there are multiple regions with substantially equal rmd ⁺ or rmd ^- , the average diameter of the largest circle included in each region may satisfy the above condition. Further, regarding the shape of each area, if there is a thin cut that has no acoustic meaning, or if a region is parallel to each other with a narrow gap, it can be considered as the same area, ignoring the cut or the gap.

As a method to change the rmd of each region of a sound insulation structure, when the cross-sectional shape of the structure is constant,
There are ways to change the density. Further, the cross-sectional shape may be modified. More about the above two methods
The rmd ⁺ and rmd ^- regions may be integrated into one, or may be separated.

It has been found that in a structure in which a plate material is partially laminated with another plate material, the mass law is approximately applied in all frequency ranges except for the coincidence limit frequency c, even if the laminated region is only partially laminated. Therefore, it is presumed that in any case, the increase in areal density of the structure constructed by the above-described method will be contributed by the mass law.

Next, a first example of the structure of the sound insulation structure according to the present invention will be described.
The figures shown in A to G in the figures are illustrative and do not limit the present invention. In A, a sound absorbing material 3 is filled between the plates 1 and 2, and the lower part of the plate is thicker than in the upper part. In B, an intermediate plate 4 is inserted between the double walls, and the upper and lower parts of this plate are The density of . C is a case where one of the planar density of the double-walled boards is much smaller than the other, for example, one is a soft sound insulating material (m = 2) and the other is a gypsum board (m
= 10), and if the lower half of the side with the lower areal density is double laminated, it is more effective to laminate the lower half with the lower areal density as shown by the rmd formula. be. D is a structure in which another sound insulating material, for example, a soft sound insulating material 5, is laminated on the lower half of one side of the double wall. In E, a partition 6 is provided horizontally in the middle of the double wall, and the lower half of the plate on the right side is thickened. F is a double wall, with a horizontal partition in the middle, the lower half of the rigid board on one side is double laminated, the surface material on the other side is a soft sound insulating material 5, and the lower half is double laminated. Along with laminating,
The type of sound-absorbing material used in the upper and lower parts is different.
G is a case in which a partition 6 is provided horizontally in the middle of the double wall, and a heavy block 7 is added to the upper one-sided board instead of being uniformly laminated. Further, although not shown, a plate member formed with a continuous slope from one end to the other end may naturally be used in the present invention.

In the sound insulation structure according to the present invention, any number of plates may be inserted into any structure, such as those illustrated in the above example, as a surface material or as an intermediate material inside. Furthermore, when joining the sound insulating structure of the present invention to a beam, etc., the effect is excellent if the joint part overlaps the boundary of the area, and it is even more advantageous to use a soft material for one of the face materials because of secondary effects. be. In other words, when joined to a rigid material such as a beam (the same applies to internal partitions), the acoustic behavior of the surrounding surface material (which increases its apparent rigidity) is likely to be affected; It is more advantageous if Note that it is clear that the sound insulation structure according to the present invention is not limited to a flat plate, but may also be a curved plate or a plate-shaped body having a curved surface in part.

The sound insulation structure according to the present invention can improve sound insulation defects caused by coincidence effects by leveling and distributing them, without increasing weight or thickness, and can also disperse sound insulation defects caused by resonance transmission, especially in the low frequency range. Conventionally, it improves by equalizing or leveling.
The sound insulation grade D-value, which has been greatly affected by these sound insulation deficiencies, can be significantly improved.

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Examples 1 and 2 and Comparative Examples 1 and 2 90cm x 240cm x 6mm (thickness) and areal density of 4.5Kg/
By adding iron powder to soft vinyl chloride in the same area between two asbestos silica boards consisting of 2.0 kg/m ² , the surface density is 2.1 kg/m ² .
Glass wool with a thickness of 25 mm (80k) is laminated in the same area on a composite board made by sandwiching a soft sound insulation sheet (manufactured by Zeon Kasei Co., Ltd., product name: Sandum S-5) with a thickness of 0.6 mm. Panel A (Comparative Example 1), which is a sound insulation structure, was prepared by further laminating the above-mentioned soft sound insulation sheet on the surface.

The same soft sound insulating sheet was laminated on the entire surface of the soft sound insulating sheet of this panel A to create panel B (comparative example 2).

Panel C (Example 1) was created by laminating the same soft sound insulating sheet as described above, ie, 90 cm x 120 cm, on half of the soft sound insulating sheet surface of Panel A.

A soft sound insulating sheet of the same size (90 cm x 120 cm) and the same properties was further laminated on the 90 cm x 120 cm soft sound insulating sheet surface of panel C to form panel D (Example 2).
It was created.

The areal densities of the board material and the soft sound insulation sheet in Comparative Example 1 (Panel A) and Comparative Example 2 (Panel B) were the same over the entire area of the board material (A: 2.1 Kg/m ² , B: 4.2
Kg/m ² ), and there is no structural region with different natural frequencies in the structure (panel), whereas in Example 1 (Panel C) and Example 2 (Panel D), the soft sound insulation sheet side The ratio between the maximum and minimum areal densities is twice as high in Example 1 and three times as high as in Embodiment 2, and each of the small areas with high areal density is 50% of the total area. Also, in the structure, the ratio of the maximum and minimum natural frequencies is 1.19 in Example 1.
In Example 2, it is 1.38 times, and the maximum and minimum vertical cross-sectional areas with respect to the sound transmission direction are each 50% of the total vertical cross-sectional area, and the diameter of each maximum circle is 90 cm. , the thickness of the structure (in Example 1
38.2 or 38.8cm, 38.2 or 39.4cm in Example 2)
Everything is bigger than that.

Sound transmission loss was measured for panels A, B, C, and D shown in Comparative Examples 1 and 2 and Examples 1 and 2. The measurement method was based on the sound transmission loss measurement method in a reverberation room based on JIS-A-1416.

The measurement results are shown in Figure 2. As shown in the figure, panel A (indicated by the dotted line) shows a significant drop in transmission loss around 250Hz, and panel B (indicated by the broken line)
Similarly, a large drop can be seen around 125 to 250 Hz, whereas panel C (indicated by a dashed line) shows a large drop around 125 to 250 Hz.
There is a considerable improvement in the dip around 250 Hz, and in panel D (shown by the solid line) there is a significant improvement in the dip. As can be seen from this figure, in the sound insulation structures according to the present invention according to Examples 1 and 2, the drop in transmission loss at c is dispersed and leveled out as a result of the synthesis of transmitted sound from regions with different acoustic behaviors. Furthermore, it can be seen that the contribution according to the mass law due to the increase in areal density is obtained in almost all frequency ranges other than c, and that the transmission loss is significantly improved.

In addition, as shown in Examples 1 and 2, it has been experimentally shown that the heterogeneous structure of the sound insulation structure according to the present invention is more effective in lightweight plate materials than in heavy plate materials.

[Brief explanation of the drawing]

Figures 1A to 1G are cross-sectional views showing configuration examples of the sound insulation structure of the present invention, and Figure 2 is a drawing showing the relationship between sound transmission loss (dB) and center frequency (Hz) in the example and comparative example. be. 1, 2...Plate material, 3...Sound absorbing material, 4...Intermediate plate, 5...Soft sound insulating material, 6...Partition, 7...Block.

Claims (1)

[Claims] 1. A sound insulating structure consisting of a multi-wall structure, in which the plate materials constituting the structure are composed of multiple regions with different areal densities m, and the multiple regions have the maximum and minimum values of the average areal density within each region. is formed such that the ratio of 1.2 or more is 1.2 or more, and the sum of the areas of the large area and the small area of the area differing by 1.2 or more is 25% or more of the total area of the plate material, and , the structure has a plurality of structural regions having different natural frequencies in a direction perpendicular to sound transmission, and the ratio of the maximum value and the minimum value of the natural frequency r of each of the plurality of structural regions. is 1.1 or more, and the sum of the cross-sectional areas of the regions where r is large and the region where r is small in a vertical section perpendicular to the sound transmission direction in regions where the ratio of r differs by 1.1 or more is the structure. It has 25% or more of the total cross-sectional area in the vertical cross section of the body, and the average diameter of the largest circle included in each of the large r area and the small r area in the vertical cross section is greater than the thickness of the structure. A sound insulation structure characterized by being large.