JPH10102428A - Sound absorption panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to mount easily a sound absorption panel on the rear surface of a girder or the like of an elevated structure and reduce effectively even a noise which enters from the slanting direction as well. SOLUTION: A sound absorption panel forms a hollow panel 3 by opposing relatively a front board 1 having a large number of openings 11 to a rear surface board 2 having a sound insulating ability where a sound absorption material enveloped with a protection film 5 is incorporated in the hollow panel 3 while an air layer 6 is formed between the front board 1 and the protection film 5, thereby enabling a noise which enters from the slanting direction to be reduced effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound-absorbing panel which is preferably mounted on the back of a girder of an elevated structure such as a vehicle traveling under an elevated structure such as a bridge or an elevated road. It is about.

[0002]

2. Description of the Related Art For example, in a place where a general road is provided under an elevated structure such as an elevated road, when a vehicle travels under the elevated structure, noise of the vehicle is generated on the underside of the girder of the elevated structure. Reflects and diffuses around, causing noise pollution. Conventionally, in order to reduce such noise, for example, the back surface of the girder is covered with a panel-shaped sound absorbing panel in which a sound absorbing material is attached behind a front plate having a number of openings, or the inside of a cylindrical body having a number of openings. A plurality of cylindrical sound-absorbing cylinders filled with a sound-absorbing material are arranged in parallel at appropriate intervals on the back surface of the girder of the elevated structure.

[0003]

However, in the case of the former sound absorbing panel such as the former, it is easy to mount on the back side of the girders because of the panel shape, and the noise that is vertically incident on the sound absorbing panel. Is effectively absorbed because sound is absorbed by the sound-absorbing material through the opening in the front panel, but noise from vehicles rarely enters from the vertical direction. The noise incident obliquely has not been effectively reduced because a part of the noise is reflected by the front panel.

In the latter sound absorbing cylinder, since it has a cylindrical shape, it has no directionality, and most of the noise that enters obliquely enters through the opening of the cylindrical body and is absorbed by the sound absorbing material. Although effectively reduced, installation on the back side of the girder is troublesome. In general, firstly, on the back side of the girder, a cross girder made of H-shaped steel extending in the width direction is attached at predetermined intervals, and the cross girder is attached to this girder. This is done by bolting the sound absorbing cylinders one by one. However, it was troublesome to mount the sound-absorbing cylinders one by one by bolting them to the cross beams.

Therefore, the present invention solves the above-mentioned problems,
It is an object of the present invention to provide a soundproof panel that can be easily attached to the back of a girder or the like and that can effectively reduce noise incident from an oblique direction.

[0006]

The inventor of the present invention has conducted intensive studies on how to reduce the noise incident from an oblique direction in the case of a panel which is easy to mount. A front panel and a back panel having sound insulation are opposed to each other to form a hollow panel, and when the sound absorbing material is provided inside the hollow panel, the sound absorbing material is wrapped with a protective film, and the protective film and It has been found that if an air layer is formed between the front panel and the front panel, noise incident from oblique directions can be effectively reduced, and the present invention has been completed.

That is, in the soundproof panel according to the present invention, a front panel having a large number of openings and a back panel having sound insulation are opposed to each other to form a hollow panel, and the hollow panel is wrapped with a protective film. A sound absorbing material is provided inside, and an air layer is formed between the front plate and the protective film.

In the present invention, if the sound absorbing material is wrapped in a protective film and an air layer is formed between the protective film and the front plate, noise entering from an oblique direction can be effectively prevented. It is not clear whether the reduction is achieved, but it is presumed to be due to the following reasons. That is, part of the noise that enters obliquely is reflected by the front panel, and part of the noise enters the hollow panel through the opening of the front panel. Part of the sound incident into the hollow panel repeats irregular reflection in the air layer between the protective film and the front plate, is absorbed by the sound absorbing material, and is attenuated by interfering with each other. A part of the incident sound is reflected by the protective film and emitted again through the opening, but the sound reflected by the protective film and emitted again is different from the sound directly reflected by the front panel by air. Since the extra layer passes through the layer, a phase difference is generated by the passage dimension. The phase difference causes the sound reflected by the protective film and the sound reflected by the front panel to interfere with each other. It is thought that the sound that is reflected and the sound reflected by the front panel are also attenuated. Therefore, noise incident from an oblique direction can also be effectively reduced, and since it is in a panel shape, it can be easily attached to the back side of the girder.

In the present invention, the back plate and the protective film may be in close contact with each other, but if an air layer is also formed between the back plate and the protective film, noise in the low frequency region is effectively reduced. Is preferred.

In the present invention, the material of the protective film is not particularly limited, and a synthetic resin film made of an appropriate material such as Teflon is generally used. However, in consideration of waterproofness and durability against rainwater and the like, polyvinyl fluoride film is used. Preferably, it is formed.

[0011]

Next, an embodiment of the present invention will be specifically described with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of the present invention, and FIG. 2 is a sectional view thereof. In this drawing, reference numeral 1 denotes a front plate, which is formed on a synthetic resin plate made of acrylic-modified vinyl chloride, polycarbonate, FRP, or the like having excellent impact resistance, or a metal plate made of zinc-iron plate, aluminum, stainless steel, or the like. A large number of portions 11 are provided, and generally, an expanded metal, a punching plate, a slit plate, or the like is used.

Reference numeral 2 denotes a back plate. The back plate 2 has a sound insulating property so as to prevent sound from leaking to the back side, and generally has the same shock resistance as the front plate 1. It is formed of a synthetic resin plate such as acryl-modified vinyl chloride, polycarbonate, or FRP, or a metal plate such as a zinc iron plate, aluminum, or stainless steel.

Reference numeral 3 denotes a hollow panel, wherein the front plate 1 is disposed on the front side and the rear plate 2 is disposed on the rear side so as to face each other, and a peripheral side plate 31 is formed around the periphery.

Reference numeral 4 denotes a sound-absorbing material provided inside the hollow panel 3, which may be a metal sound-absorbing material such as aluminum fiber or open-celled aluminum foam, but is preferably inexpensive and lightweight glass wool or rock wool. Used, other, open-celled polyolefin foam, foamed resin such as urethane foam, resin fiber non-woven fabric such as polyester fiber non-woven fabric, metal fiber bonded via a binder, metal powder and particles,
A material made of a sintered material obtained by sintering ceramic powder, particles, metal short fibers, or the like is appropriately used, and is not particularly limited. The thickness of the sound-absorbing material 4 is not particularly limited. The thicker the sound-absorbing material, the better the sound-absorbing property. However, in consideration of the ease of installation due to the weight and size, the thickness is generally about 50 to 150 mm. You.

Reference numeral 5 denotes a protective film for wrapping the sound absorbing material 4. A synthetic resin film made of an appropriate material such as Teflon is generally used. In particular, a polyvinyl fluoride film is preferable in consideration of waterproofness and durability against rainwater and the like. is there.

Reference numeral 6 denotes an air layer formed between the front panel 1 and the protective film 5. Due to the thickness of the air layer 6, the sound reflected by the protective film 5 and emitted to the outside again has a predetermined phase difference with respect to the sound directly reflected by the front panel 1. By appropriately changing the
It is considered that the front panel 1 can be attenuated by interfering with a predetermined frequency included in the sound directly reflected by the front panel 1. Regarding vehicle noise, the thickness of the air space 6 is generally 5 to 5.
Although it is about 50 mm, it is not particularly limited.

In order to mount the sound absorbing panel having the above-mentioned configuration on, for example, the back surface of a girder of an elevated structure, first, a horizontal girder made of H-shaped steel extending in the width direction is mounted on the back surface of the girder of the elevated structure at every interval of the sound absorbing panel. The sound-absorbing panel may be bolted to the cross girder with the face plate 2 facing the back surface of the girder, or the end may be inserted between the flanges of the opposing cross girder and locked. The method is not limited.

FIG. 3 is a sectional view showing another embodiment of the present invention. This embodiment differs from the embodiment shown in FIGS. Between the back plate 2 and the protective film 5, the back plate 2 and the protective film 5 may be in close contact as shown in FIGS. Air layer 7
Is preferable because noise in the low frequency region is effectively reduced.

In FIGS. 1 and 2 and FIG. 3, an air layer 6 formed between the front panel 1 and the protective film 5 includes:
A material having a high porosity as long as the reflection by the protective film 5 is not impaired, for example, a nonwoven fabric, a lattice material, or a continuous foam material may be mounted. Similarly, a material having a high porosity may be attached to the air layer 7 between the back plate 2 and the protective film 5.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an aperture ratio of 57.times.
A hollow panel 3 is formed by opposing a front plate 1 made of an aluminum punched plate having an opening 11 formed at 9% and a sound insulating back plate 2 made of a zinc iron plate to face each other.
Inside, a 100 mm thick sound absorbing material 4 made of glass wool wrapped with a protective film 5 made of a 21 μm thick polyvinyl fluoride film is formed, and a 30 mm thick air layer 6 is formed between the front plate 1 and the protective film 5. A sound absorbing panel of the present invention as Example 1 was prepared.

Next, in the form shown in FIG. 3, the aperture ratio is 57.9.
% Of a perforated aluminum plate and a sound-insulating back plate 2 made of a zinc-iron plate are wrapped with a protective film 5 made of a polyvinyl fluoride film having a thickness of 21 μm in a hollow panel 3 formed so as to face each other. A sound absorbing material 4 made of glass wool and having a thickness of 75 mm is provided therein, an air layer 6 having a thickness of 5 mm is formed between the front panel 1 and the protective film 5, and a 15 mm layer is also provided between the rear panel 2 and the protective film 5.
The sound absorbing panel of the present invention as Example 2 in which the air layer 7 was formed was prepared.

Next, as Comparative Example 1, unlike the above-mentioned Example 1, a conventional sound-absorbing panel in which the air layer 6 was not formed between the front plate 1 and the protective film 5 and the other parts were the same as in Example 1 was used. Created.

Further, as a comparative example 2, unlike the above-described embodiment 2, an air layer 6 is not provided between the front panel 1 and the protective film 5, and an air layer 7 between the rear panel 2 and the protective film 5 is provided.
A conventional sound-absorbing panel was prepared in the same manner as in Example 2 except that the thickness was 20 mm.

The oblique incidence sound absorption coefficient was measured for the above Examples and Comparative Examples, and the measurement results are shown in FIG. 4 for Examples 1 and Comparative Example 1, and FIG. 5 for Examples 2 and Comparative Example 2, respectively. Was.

As shown in FIG. 6, the method for measuring the oblique incidence sound absorption coefficient is such that each test piece S composed of the sound absorbing panel is placed on the floor (flat rigid wall) in the test chamber and the incident angle θ Are set to 0 degree (normal incidence), 15 degrees, 30 degrees, and 45 degrees, and a value obtained by averaging the sound absorption coefficients obtained at each angle is defined as an oblique incidence sound absorption coefficient. The graph is plotted with the 1/3 octave center frequency Hz on the axis. 6A shows the case where the incident angle θ is 0 degrees, and FIG. 6B shows the arrangement of the sound source P and the sound receiving point Q when the incident angle θ is other than 0 degrees.

Referring to the graph of FIG. 4, comparing Example 1 with Comparative Example 1, Example 1 in which the air layer 6 was formed between the front plate 1 and the protective film 5 has the air layer 6 formed. As compared with Comparative Example 1 which does not have the same, the oblique incidence sound absorption coefficient is superior, and according to the graph of FIG. 5, Examples 2 and Comparative Example 2 in which the air layer 7 is also formed between the back plate 2 and the protective film 5 are shown. It was confirmed that Example 2 in which the air layer 6 was formed between the front panel 1 and the protective film 5 was superior in oblique incidence sound absorption coefficient to Comparative Example 2 in which the air layer 6 was not formed. Is done.

[0028]

According to the present invention, a sound absorbing material wrapped with a protective film is provided inside a hollow panel formed by opposing a front plate having a large number of openings and a back plate having sound insulation. In addition, since an air layer is formed between the front plate and the protective film, noise incident from the vertical direction is absorbed by the sound absorbing material through the opening of the front plate, and Also, noise that enters obliquely is absorbed by the sound absorbing material, is effectively attenuated by the protective film and the air layer, and is easy to mount because of the panel shape. Therefore, the present invention can be suitably installed on the backside of a girder of an elevated structure that is difficult to install and has a lot of noise incident obliquely, and can also be suitably used as a soundproof wall installed in a vertical wall shape on a side edge of a road. .

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a sectional view of FIG.

FIG. 3 is a sectional view showing another embodiment of the present invention.

FIG. 4 is a graph showing a measurement result of an oblique incidence sound absorption coefficient.

FIG. 5 is another graph showing the measurement results of the oblique incidence sound absorption coefficient.

FIG. 6 is an explanatory diagram showing a method of measuring an oblique incidence sound absorption coefficient.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Front plate 11 Opening 2 Back plate 3 Hollow panel 31 Peripheral plate 4 Sound absorbing material 5 Protective film 6 Air layer between front plate and protective film 7 Air layer between back plate and protective film

Claims (3)

[Claims] 1. A hollow panel is formed by opposing a front plate having a large number of openings and a rear plate having sound insulation.
A sound absorbing panel, wherein a sound absorbing material wrapped with a protective film is provided inside the hollow panel, and an air layer is formed between the front panel and the protective film. 2. The sound absorbing panel according to claim 1, wherein an air layer is also formed between the back plate and the protective film. 3. The sound-absorbing panel according to claim 1, wherein said protective film is made of a polyvinyl fluoride film.