JP2004264589A - Wall member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wall member which can be made lightweight by being reduced in capacity by optimizing the thickness of a structure member according to the acoustic mode of object sound to be reduced. <P>SOLUTION: The wall member is equipped with a sound absorbing wall 20 and a sound blocking wall 30 which are arranged one over the other; and the sound absorbing wall 20 has a thin part 21 and a thick part 22 and the sound blocking wall 30 has a thin part 31 and a thick part 32 so that the thick part 22 is arranged corresponding to a part where a particle speed is higher than a speed reference value and the thick part 32 is arranged corresponding to a a part where a sound pressure level is larger than a reference sound pressure value according to the acoustic mode of the object sound to be reduced. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wall member for reducing noise, and more particularly to a wall member capable of reducing the required volume and reducing the weight.
[0002]
[Prior art]
BACKGROUND ART Conventionally, wall members such as enclosures of motors / electrical machines and road noise barriers are formed by combining sound insulation walls and sound absorption walls, and in general, the cross section at any position has the same thickness and structure. (See Patent Documents 1 and 2).
[0003]
[Patent Document 1]
JP-A-10-203267
[Patent Document 2]
JP-A-2002-73036
[Problems to be solved by the invention]
The wall member described above has the following problem. That is, since the sound to be reduced has a certain acoustic mode when it reaches the wall member, the particle velocity and the sound pressure are not always uniform in each part. Therefore, the required thickness of the wall member is naturally different between a place where the particle velocity is low and a place where the particle velocity is high, and a place where the sound pressure is low and a place where the sound pressure is high.
[0006]
In general, the wall member is configured with a thickness that corresponds to the maximum particle velocity and the maximum sound pressure of the sound to be reduced.Therefore, there must be places with excessive thicknesses that are not required originally. It becomes. That is, there is a portion using an unnecessary material, and the volume and the weight become excessive. For this reason, in the case of a road noise barrier covering a large area, a burden is imposed on the waste and transportation of materials, and in the case of an enclosure such as a motor and an electric device, the performance of the system may be deteriorated.
[0007]
Therefore, an object of the present invention is to provide a wall member that can minimize the volume and reduce the weight by optimizing the thickness of the structural member according to the acoustic mode of the sound to be reduced.
[0008]
[Means for Solving the Problems]
In order to solve the above problems and achieve the object, a wall member of the present invention is configured as follows.
[0009]
A wall member disposed between the sound generation side and the sound receiving side, including a sound insulating wall and a sound absorbing wall which are stacked and arranged, wherein the sound absorbing wall has a first thickness. And a second sound absorbing member having a second thickness greater than the first thickness, wherein the sound insulating wall has a first sound insulating member having a third thickness, and a second sound absorbing member having a second thickness greater than the third thickness. A second sound-absorbing member having a thickness of 4 and a second sound-absorbing member corresponding to a portion where the particle velocity is higher than the velocity reference value, based on the acoustic mode of the sound to be reduced, and a sound pressure level. Is characterized in that the second sound insulating member is arranged corresponding to a portion where the sound pressure is larger than the sound pressure reference value.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a perspective view showing a wall member 10 according to one embodiment of the present invention. As shown in FIG. 1, the wall member 10 is provided between a noise source (a sound to be reduced) S and a sound receiving position R. The wall member 10 is provided with a sound absorbing wall 20 formed of a sound absorbing material such as styrene foam, urethane, rock wool, and glass wool and a sound insulating wall 30 formed of a metal material such as iron.
[0011]
The sound absorbing wall 20 includes a thin portion 21 having a thickness of 50 mm (first thickness) and a thick portion 22 having a thickness of 100 mm (second thickness) provided along a peripheral portion of the thin portion 21. It has. The sound insulation wall 30 includes a thin portion 31 having a thickness of 2 mm (third thickness) and a thick portion 32 having a thickness of 4 mm (fourth thickness).
[0012]
The thick portion 22 of the sound absorbing wall 20 and the thick portion 32 of the sound insulating wall 30 are determined as follows. That is, the stationary acoustic mode is determined by analysis or experiment, and the distribution of sound pressure and particle velocity in the wall member 10 is determined. Here, a region α equal to or higher than the predetermined particle velocity reference value and a region β equal to or higher than the sound pressure reference value are extracted. Then, the thick portion 22 is arranged so as to correspond to the region α, and the thick portion 32 is arranged so as to correspond to the region β. Therefore, it is possible to increase the sound absorption by arranging the thick portion 22 where the particle velocity is high, and to increase the wall transmission loss by arranging the thick portion 32 where the sound pressure is high.
[0013]
FIGS. 4A and 4B are diagrams showing a comparison between a conventional wall member and the wall member according to the present embodiment. The sound pressure level and weight of each of the 1.5 m × 2.0 m wall members were measured.
[0014]
FIG. 4A is a comparative example based on the thickness of the sound absorbing material. That is, Comparative Example 1 (no sound absorbing material), Comparative Example 2 (75 mm uniform), Comparative Example 3 (100 mm uniform), and Example 1 (wall member 10) are shown. In Example 1, compared to Comparative Example 2, an increase in sound absorbing performance of about 2 dB can be obtained with substantially the same volume. On the other hand, the same sound absorbing performance can be obtained with a volume reduction of 20% as compared with Comparative Example 3. That is, the volume can be significantly reduced despite the substantially same sound absorbing performance.
[0015]
FIG. 4B is a comparative example based on the thickness of the sound insulating material. That is, Comparative Example 4 (3 mm uniform), Comparative Example 5 (4 mm uniform), and Example 2 (wall member 10) are shown. In Example 2, an increase in sound insulation performance of 1.9 dB is obtained with a 1% weight increase compared to Comparative Example 4. On the other hand, compared to Comparative Example 5, a 26% reduction in weight results in a 0.3 dB reduction in sound insulation performance. That is, although the sound insulation performance is almost the same, the weight can be significantly reduced.
[0016]
As described above, the wall member 10 according to the present embodiment has the thick portion 22 only at the portion where the particle velocity is high and the thick portion only at the portion where the sound pressure is high, based on the distribution of the particle speed and the sound pressure. Since the portion 32 is provided, the overall volume can be reduced and the weight can be reduced. For this reason, when used for road noise barriers covering a large area, materials can be saved and transportation efficiency can be improved, and when used for enclosures of motors and electrical equipment, the performance of the system can be improved. Can be improved.
[0017]
Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements in an implementation stage without departing from the scope of the invention. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Further, components of different embodiments may be appropriately combined.
[0018]
【The invention's effect】
According to the present invention, by optimizing the thickness of the structural member according to the acoustic mode of the sound to be reduced, the volume can be minimized and the weight can be reduced.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a wall member according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a relationship between a particle velocity distribution of the wall member and a thickness of a sound absorbing wall.
FIG. 3 is an explanatory diagram showing a relationship between a sound pressure distribution of the wall member and a thickness of the sound absorbing wall.
FIG. 4 is an explanatory view showing an effect of the wall member.
[Explanation of symbols]
10 wall member, 20 sound absorbing wall, 21 thin part (first sound absorbing member), 22 thick part (second sound absorbing member), 30 sound insulating wall, 31 thin part (first sound insulating member), 32 ... Thick part (second sound insulation member)

Claims (1)

In the wall member arranged between the reduction target sound generation side and the sound reception side,
With a sound insulation wall and a sound absorption wall arranged in a stack,
The sound absorbing wall includes a first sound absorbing member having a first thickness and a second sound absorbing member having a second thickness greater than the first thickness.
The sound insulation wall includes a first sound insulation member having a third thickness and a second sound insulation member having a fourth thickness greater than the third thickness.
Based on the acoustic mode of the sound to be reduced, the second sound absorbing member is disposed corresponding to a portion where the particle velocity is higher than the velocity reference value, and the sound pressure level is corresponding to a portion higher than the sound pressure reference value. A wall member on which a second sound insulation member is arranged.

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