JP6151099B2 - Soundproof unit - Google Patents

Description

  The present invention provides, for example, a flow resistance material as a suppressor for an edge effect (the presence of a region where the particle velocity is very large in the vicinity of the edge) which is installed on a temporary enclosure at a construction site and exhibits a noise reduction effect. The soundproof unit is composed of the outer frame.

  Conventionally, as a noise countermeasure at a construction site, a method of reducing noise by diffracting sound by building a soundproof wall between a noise source and a sound receiving point is generally used (see Patent Document 1). And in order to enhance the noise reduction effect, it can be realized by increasing the height of the soundproof wall, but on the other hand, the landscape and sunshine are obstructed, the feeling of pressure increases, the installation cost increases, the safety decreases, etc. Problems may occur. In such a situation, it is known that a large noise reduction effect (edge effect suppression) can be obtained for the diffracted sound field by installing an appropriate flow resistance material at the tip of the soundproof wall.

JP 2012-172358 A

  However, when the flow resistance material is attached to the top of a soundproof wall such as a temporary enclosure or a temporary soundproof panel, an outer frame that holds and reinforces the flow resistance material, which is necessary for structural strength, There is a difference in the noise reduction effect depending on the length and height of the edge. In such a situation, in order to prevent the noise reduction effect from deteriorating due to the presence of the outer frame, what is the most suitable outer frame is what shape, size, and the like is to be used. The soundproof unit according to the present invention has been proposed in order to solve such a problem.

The gist for solving the above-mentioned problems of the soundproof unit according to the present invention and achieving the object is a flow resistance material that is attached to the top of the soundproof wall and has a noise reduction effect, and a support reinforcing member provided on the outer periphery thereof. in soundproofing unit comprising at an outer frame, that the only portion of the outer frame of the plane perpendicular to the plane of the flow resistance material provided at the top of the flow resistance member, are provided a plurality of holes to penetrate in the thickness direction It is to make it a single flat plate with an aperture ratio of the outer frame of 40%.

According to the soundproof unit according to the present invention, the outer frame at the top of the flow resistance material is made of a perforated plate, so that the reflection of sound is reduced and the noise reduction effect is not reduced. Accordingly, the soundproofing wall such as the temporary enclosure can be sufficiently exhibited without lowering the noise reduction effect of the flow resistance material by the soundproofing unit without setting the soundproofing wall high.
Since the arrangement of the holes in the perforated plate is any one of a lattice arrangement, a staggered arrangement, and a random arrangement, the reflected sound is efficiently suppressed.

FIG. 3 is a perspective view (A), a front view (B), and a side view (C) of the soundproof unit 1 according to the present invention in a state in which the outer frame is a frame D (perforated plate 6). It is the top view (A) of the perforated board (punching metal) 6 of the soundproof unit 1 which concerns on the same invention, and the partially expanded plan view (B) which shows arrangement | positioning of the hole 6a. FIG. 3A is a diagram showing the positions of a sound source and measurement points, and FIG. The perspective view (A) which shows the aspect (frame A), the front view (B), and the side view (C) for measuring the noise reduction effect in the full-scale experiment on the outer frame of the soundproof unit. It is the front view (A) and side view (B) which show the aspect (frame B) for measuring the noise reduction effect in the full-scale experiment of the outer frame of the soundproof unit. It is the front view (A) and side view (B) which show the aspect (frame C) for measuring the noise reduction effect in a full-scale experiment on the outer frame of the soundproof unit. It is the front view (A) and side view (B) which show the aspect (frame E) for measuring the noise reduction effect in the full-scale experiment on the outer frame of the soundproof unit. It is a figure which shows the relative sound pressure level in each frequency in the aspect (frame A-frame E) on the case where a frame is not provided as a reference level.

  As shown in FIG. 1, the soundproof unit 1 according to the present invention has a perforated plate 6 at the top (top) of the outer frame surrounding the flow resistance material.

  The soundproof unit 1 includes a flow resistance material 2 that is attached to the top of a soundproof wall such as a temporary enclosure or a temporary soundproof wall at a construction site, and has a noise reduction effect, and an outer frame for supporting reinforcement provided on the outer periphery thereof. 3

  As shown in FIG. 1, a perforated plate provided with a plurality of holes 6a through which a portion of the outer frame 3a provided on the top of the flow resistance material 2 is penetrated in the plate thickness direction as shown in FIG. 6 is, for example, a metal punching metal (t = 2 mm, width 50 mm) 6.

  As an example, the shape of the flow resistance material 2 is approximately 600 mm long × 1000 mm wide × 5.6 mm wide (the thickness of one layer is about 0.8 mm) or 4.8 mm wide (one layer as shown in FIG. 1). Is a rectangular body having a thickness of about 1.6 mm.

  Furthermore, the flow resistance material 2 is a porous material as an example, and as shown in FIG. 3B, the seven first members to the seventh member, or the three first members to the first member. The three members (not shown) are configured with a gradation that gradually changes the number of layers in the thickness direction, and are overlapped at a lower position as shown.

  The outer frames 3b to 3d other than the top of the flow resistance material 2 in the outer frame 3 are, as an example, wooden and have a thickness of 25 mm and a width of 50 mm.

  The arrangement of the holes 6a in the perforated plate (punching metal) 6 of the outer frame 3a is, for example, a staggered arrangement as shown in FIGS. The arrangement of the holes 6a is not particularly limited, and may be a lattice arrangement or a random arrangement. The diameter of the holes 6a is, for example, φ10 mm, the hole pitch is 15 mm, and the aperture ratio is 40.2%.

  The soundproof unit 1 is attached to a temporary enclosure as the soundproof wall to measure the noise reduction effect, and the noise reduction effect in other outer frame modes is measured to compare the degree of reduction in the noise reduction effect. The situation of the large experiment will be described.

  In the experiment, as shown in FIG. 3 (A), the soundproof unit 1 is placed on the tip of a temporary enclosure having a width of 2 m, a depth of 2 m, and a height of 3 m on a flat asphalt surface with few reflections in the outdoors. Install. The positions of the sound source and measurement point are also shown.

  The sound source was the center of the temporary enclosure, 2 m from the ground surface, and a dodecahedron speaker was prepared. The test sound is pink noise and the input voltage is constant regardless of the measurement status. Thus, the state of the upper frame of the soundproof unit 1 is changed, and the sound pressure level inside and outside the temporary enclosure is measured.

About the aspect of the outer frame 3, for example,
As the frame A: As shown in FIG. 4, a wooden frame 3a, a frame 3b,
A frame 3c and a frame 3d are provided. The frame 3a is the same as the frame 3d.
As the frame B: As shown in FIG. 5, an opening (gap) 4 is provided at the top of the flow resistance material 2,
An outer frame 3a, a frame 3b, a frame 3c, and a frame 3d are provided on the outside.
The frame 3a is the same as the frame 3d.
As frame C: As shown in FIG. 6, the width of the outer frame is all made 25 mm in order to halve the width. The front view is the same as the frame A.
As a frame D: This is an embodiment of the soundproof unit 1 according to the present invention, and a perforated plate (punching metal) 6 is provided in the top outer frame 3a as shown in FIG.
As the frame E: As shown in FIG. 7, an opening 4 having a height of 10 mm and an aluminum plate 5 having a height of 90 mm are provided on the top thereof, and an outer frame 3a, a frame 3b, a frame 3c,
A frame 3d is provided. The frame 3a is the same as the frame 3d.
Each aspect was prepared as described above, and a full-scale experiment was conducted.

  From the measurement results, the relative sound pressure level for each aspect (frame A to frame E) is calculated with the case where no frame is provided (when only the flow resistance material 2 is installed) as the reference level. FIG. 8 shows the relative sound pressure levels for each condition at a position 4 m away from the temporary enclosure and at a height of +1.5 m from the ground surface.

  As a result, when the frequency is 125 Hz to 500 Hz, the relative level is almost 0 dB under any condition, and there is no reduction in the noise reduction effect due to the difference in frame. At 1 kHz, a clear increase in the relative sound pressure levels of frame B and frame E, that is, a decrease in noise reduction effect is observed.

  The relative sound pressure level of 2 to 4 kHz is clearly different due to the difference in the frame, and the frame D (in the case of the soundproof unit 1) is less than 2 dB, whereas the frame A and the frame C are about 3 dB, the frame B And the frame E are 5 dB or more.

  In the 4 kHz band, the difference due to the difference in the frame is the largest. For example, if the fore edge of the outer frame is shortened (frame A 50 mm → frame C 25 mm), the relative sound pressure level is generally reduced. However, it exceeds 2 dB at most measurement points.

  When the opening 4 (gap) is provided in the flow resistance member 2 and the outer frame 3a at the top, it exceeds 5 dB at most measurement points regardless of the presence or absence of the aluminum plate 5. On the other hand, in the frame D in which the top outer frame 3a is a perforated plate (punching metal) 6, there are hardly any measurement points at which the relative sound pressure level exceeds 2 dB.

  As described above, when the punched metal 6 is used as the perforated plate 6 having the hole 6a in the top frame of the flow resistance material 2, for example, the soundproof unit 1 is a high-performance sound insulation wall that suppresses the edge effect. The unit 1 can be applied to a soundproof wall such as a temporary soundproof panel or a temporary enclosure.

  The soundproof unit according to the present invention is not limited to temporary soundproof panels and temporary enclosures at construction sites, but can be widely applied to permanent soundproof walls.

1 Soundproof unit,
2 Flow resistance material,
3 outer frame, 3a outer frame at the top,
3b-3d outer frame of side and bottom,
4 opening,
5 Aluminum plate,
6 Perforated plate (punching metal),
6a hole.

Claims (1)

In the soundproof unit composed of a flow resistance material that is attached to the top of the soundproof wall and has a noise reduction effect, and an outer frame for supporting reinforcement provided on the outer periphery thereof,
Provided with a plurality of holes through only the outer frame portion of the plane perpendicular to the plane of the flow resistance material provided at the top of the flow resistance material in the plate thickness direction, the aperture ratio of the outer frame is 40% A single plate-shaped perforated plate,
Soundproof unit characterized by.

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