JP6936904B2 - Sound insulation louver - Google Patents

Description

The present invention relates to a sound insulation louver capable of ensuring breathability, excellent design, and sufficient sound insulation performance.

When equipment such as an air conditioner outdoor unit is installed on the roof of a building or on the ground, a blind wall is installed to hide the equipment from the surroundings. A louver wall is preferred for this blind wall because of the need for ventilation and design requirements.

On the other hand, in order to prevent the noise generated from the equipment from propagating to the surroundings, the blind wall is required to have high sound insulation performance. Conventionally, soundproof louvers have been proposed in order to reduce the noise transmitted from the voids in the louver wall.

For example, in Patent Document 1 (Japanese Unexamined Patent Publication No. 2013-213334), a louver main body 11 provided with an opening 13 for inserting a sound absorbing material 50 on the opposite surface of the decorative surface 12 and an opening of the louver main body 11 are provided. A sound absorbing louver provided with a cover material 30 covering the 13 is disclosed.
Japanese Unexamined Patent Publication No. 2013-213334

The conventional sound absorbing louver is mainly composed of a louver body, a sound absorbing material such as glass wool, and a holding member of the sound absorbing material, and a member for joining them is also required, which causes an increase in the number of members and a complicated structure.

The increase in the number of members and the complexity of the structure lead to an increase in the cost of the members themselves and an increase in the man-hours in manufacturing, transportation, and construction.

As described above, many of the conventional sound absorbing louvers proposed to satisfy the breathability, design and sound insulation performance have a problem that they are expensive due to the complexity of the structure.

In addition, the conventional sound absorbing louver is generally designed to effectively absorb noise at a specific noise incident angle, but in general, noise is sufficiently incident on the louver wall from various directions. There was also a problem that good sound insulation performance could not be ensured.

The present invention solves the above-mentioned problems, and the sound insulation louver according to the present invention includes a first straight line portion, a second straight line portion parallel to the first straight line portion, and the above-mentioned sound insulation louver according to the present invention. A plurality of louver blade members having a parabolic portion extending from the second straight line portion are continuously arranged, and the louver blade member has an arc portion extending from the first straight line portion and has the parabolic portion. The focal point formed by the arc portion and the focal point formed by the arc portion are the same points .

Further, in the sound insulation louver according to the present invention, the louver blade member is arranged so that the first straight line portion of one of the louver blade members is parallel to the second straight line portion of the other louver blade member. It is characterized in that a plurality of them are continuously arranged.

According to the sound insulation louver according to the present invention, only the louver blade member is required, the number of parts can be suppressed, and the structure is simple, so that the cost associated with the increase in manufacturing, transportation, and construction man-hours can be reduced. Can be done.

Further, according to the sound insulation louver according to the present invention, it is possible to deal with noise from various directions and secure sufficient sound insulation performance.

It is a figure which shows the louver blade member 10 used for the sound insulation louver 1 which concerns on embodiment of this invention. It is a figure which shows the sound insulation louver 1 which concerns on embodiment of this invention. It is a figure explaining the principle of the sound insulation louver 1 which concerns on embodiment of this invention. It is a figure explaining the principle of the sound insulation louver 1 which concerns on embodiment of this invention. It is a figure which shows the numerical analysis target. It is a figure which shows the result of the numerical analysis. It is a figure explaining the slit resonator applied to the sound insulation louver 1. It is a figure which shows the numerical analysis target of the sound insulation louver 1 to which a slit resonator is applied.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, a single louver blade member 10 constituting the sound insulation louver 1 will be described. FIG. 1 is a diagram showing a louver blade member 10 used in the sound insulation louver 1 according to the embodiment of the present invention.

The sound insulation louver 1 is configured by arranging a plurality of louver blade members 10 at predetermined intervals. Here, in FIGS. 1 to 4, the louver blade member 10 and the sound insulation louver 1 are viewed in cross section with respect to the longitudinal direction. Therefore, the louver blade member 10 and the sound insulation louver 1 have a length as a long body in the depth direction of the paper surface.

Further, although the structure of the louver blade member 10 is referred to as a "straight line portion" or the like, the actual shape is a flat portion.

The louver blade member 10 is preferably made of a material having rigidity and a large acoustic transmission loss, and for example, aluminum or the like can be used.

The louver blade member 10 has a first straight line portion 31, a second straight line portion 32 parallel to the first straight line portion 31, and a parabolic portion 40 extending from the second straight line portion 32. The parabolic unit 40 functions as a sound reflecting unit.

The first straight line portion 31 and the second straight line portion 32 are connected by the third straight line portion 33, and are surrounded by the first straight line portion 31, the second straight line portion 32, and the third straight line portion 33. Reinforcing ribs 60 are provided in the space.

The louver blade member 10 has an arc portion 50 extending from the first straight line portion 31 via the fourth straight line portion 34. The arc portion 50 functions as a sound reflecting portion.

A plurality of louver blade members 10 as described above are arranged at predetermined intervals so that the first straight line portion 31 and the second straight line portion 32 of all the louver blade members 10 are parallel to each other. The sound insulation louver 1 is configured.

That is, in the sound insulation louver 1, the first straight line portion 31 of one louver blade member 10 is arranged so as to be parallel to the second straight line portion 32 of the other louver blade member 10. FIG. 2 is a diagram showing a sound insulation louver 1 according to an embodiment of the present invention.

As shown in FIG. 2, as long as each louver blade member 10 is fixed, any method may be used for fixing the louver blade member 10. Further, in the sound insulation louver 1 shown in the figure, it is assumed that the left side thereof is the noise source side where equipment and the like are installed, and the right side is the sound receiving side.

By arranging the plurality of louver blade members 10 as shown in FIG. 2, a ventilation path 15 is formed between the adjacent louver blade members 10. The opening of the ventilation path 15 on the noise source side is defined as the first opening 11. Further, the opening of the ventilation path 15 on the sound receiving side is defined as the second opening 12.

The structure that characterizes the sound insulation louver 1 according to the present invention is described below. First, it has a ventilation path (section A) composed of parallel and opposed wall surfaces composed of a first straight line portion 31 and a second straight line portion 32.

Further, as the second characteristic structure of the sound insulation louver 1 according to the present invention, a parabolic curved surface (section B) is provided as an inner wall of the ventilation path 15.

Further, as a third characteristic structure of the sound insulation louver 1 according to the present invention, an arc curved surface (section C) is provided as an inner wall of the ventilation path 15.

Further, as the fourth characteristic structure of the sound insulation louver 1 according to the present invention, the parabolic curved surface (section B) and the arc curved surface (section C) have the point D as a common focus.

Further, as a fifth characteristic structure of the sound insulation louver 1 according to the present invention, the ventilation path 15 is configured in the order of section A, section B, and section C from the first opening 11 on the noise source side.

Next, the principle that the sound insulation louver 1 according to the present invention reduces the noise transmitted through the ventilation path 15 will be described below. Further, FIGS. 3 and 4 show diagrams for explaining the principle of the sound insulation louver 1 according to the present invention. In the figure, the arrows indicate the direction of the sound wave flow of noise.

In FIG. 3, as shown in (0), noise is incident on the first opening 11 of the sound insulation louver 1 from various directions.

As shown in (1), the noise incident on the section A of the ventilation path 15 propagates in the section A as a plane wave at a frequency in which the width of the section A (distance between 31 and 32) is half a wavelength or less.

Next, as shown in (2), the sound wave propagating in the section A as a plane wave and reflected by the parabolic surface of the section B converges toward the focal point D.

Next, as shown in (3), the sound wave that has passed through the focal point D is incident on the arc curved surface of the section C.

Next, as shown in FIG. 4 (4), the sound wave reflected by the arc curved surface of the section C converges again toward the focal point D.

Subsequently, as shown in (5), the sound wave that has passed through the focal point D is incident on the parabolic surface of the section B.

Next, as shown in (6), the sound wave reflected by the parabolic curved surface of the section B propagates in the section A as a plane wave and is re-radiated to the first opening 11 on the noise source side.

As described above, according to the sound insulation louver 1 according to the present invention, the noise propagating in the ventilation path 15 of the sound insulation louver 1 is re-radiated to the noise source side to reduce the noise transmitted through the ventilation path 15 and to insulate the sound. The sound insulation performance of the louver 1 can be improved.

Further, according to the sound insulation louver 1 according to the present invention, only the louver blade member 10 is required, the number of parts can be suppressed, and the structure is simple, so that the cost associated with the increase in manufacturing, transportation, and construction man-hours is required. Can be reduced.

Further, according to the sound insulation louver 1 according to the present invention, it is possible to deal with noise from various directions and secure sufficient sound insulation performance.

According to the sound insulation louver 1 according to the present invention, it is possible to reduce the noise transmitted through the ventilation path 15 regardless of the noise incident angle.

Further, according to the sound insulation louver 1 according to the present invention, since the louver wall can be formed only by the louver blade member 10, the number of members can be reduced and the structure can be simplified.

Further, the main body of the louver blade member 10 is a long body having the same cross-sectional view, and in addition to the reduction in the number of members and the simplification of the structure, the manufacturing cost is reduced, the transportation cost is reduced, and the installation is simple and efficient. Therefore, effects such as reduction of construction cost can be expected.

Here, in the sound insulation louver 1 according to the present embodiment described above, the sound wave incident on the first opening 11 is made into a plane wave in the section A, and this is reflected by the parabolic curved surface of the section B composed of the parabolic portion 40. After passing through the focal point D once, it is converged again toward the focal point D by the arc curved surface of the section C composed of the arc portion 50, and further reflected by the parabolic curved surface of the section B composed of the parabolic portion 40. The section A is propagated as a plane wave and emitted to the first opening 11 on the noise source side, but the embodiment of the sound insulation louver 1 according to the present invention is not limited to this.

The sound insulation louver 1 according to the present invention uses a sound wave incident from the first opening 11 of the sound insulation louver 1 as a plane wave, reflects it by a plurality of reflecting portions in the ventilation path 15, and again causes a noise source from the first opening 11. If the configuration is such that the light is emitted to the side, the present invention is not limited to the reflecting portion composed of the radial curved surface, the arc curved surface, or the like described in the embodiment.

That is, the sound insulation louver 1 according to the present invention has a technique of emitting sound waves incident from the first opening 11 of the sound insulation louver 1 again from the first opening 11 by giving a feature to the shape in the ventilation path 15. It includes all ideas.

Further, the sound insulation louver 1 according to the present invention has a technical idea that a focal point of a sound wave is formed in the ventilation path 15 by giving a feature to the shape in the ventilation path 15, and sound insulation is achieved by utilizing this focus. Also includes. Although there is a demerit that the number of parts increases, for example, arranging a sound absorbing material at the focal point D in the embodiment to absorb sound at the focal point D is also included in the sound insulating louver 1 according to the present invention. ..

Hereinafter, the sound insulation effect of the sound insulation louver 1 according to the present invention has been confirmed by numerical analysis, and the results are shown below. FIG. 5 is a diagram showing a numerical analysis target.

The two-dimensional boundary element method was used in the following numerical calculations. The calculation target is a louver wall in which louver blade members are arranged at regular intervals. FIG. 5 shows a part of the louver wall to be calculated. In this example, the louver blade members are arranged at intervals of 120 mm, and the gap between the louver blade members, that is, the width of the ventilation path is about 31 mm. The surface of the louver blade member was calculated as completely reflective. As the sound source, a point sound source was placed at a position 2 m on the left side of the drawing from the louver wall, and the sound energy transmitted to the sound receiving side (right side of the drawing) of the louver wall was calculated.

The space on the sound source side and the space on the sound receiving side are connected by an opening having a height of 1.3 m, and a louver wall is arranged in the opening. For comparison, the sound energy transmitted through a simple opening where the louver wall is not placed was calculated, and the amount of reduction in sound energy due to the presence or absence of the louver wall was evaluated as the insertion loss of the sound insulation louver, that is, the noise reduction performance.

In the numerical calculation, pure tones are performed every 1/15 octave, and the obtained sound energy transmitted to the receiving side is averaged by 5 each centered on the 1/3 octave band center frequency to 1/3. It was used as the calculation result of the octave band. From the obtained calculation results, the amount of reduction in sound energy due to the louver wall based on the simple opening was calculated as described above, and used as the insertion loss of the sound insulation louver.

FIG. 6 shows the frequency characteristics of the insertion loss of the sound insulation louver shown in FIG. The larger the value, the higher the noise reduction performance. In order to distinguish it from the case where the slit resonator described later is incorporated, the result based on the sound insulation louver shown in FIG. 5 is referred to as "basic type".

From FIG. 6, it can be seen that a positive insertion loss is obtained in a wide frequency range, and the transmitted noise can be reduced while ensuring the air permeability of the louver wall. In particular, an insertion loss of 5 dB or more is obtained at a frequency of 2 kHz or more. However, it can be seen that the insertion loss is reduced in the band centered on 1 kHz. This measure is proposed below.

As described above, the basic type sound insulation louver reduces the insertion loss in the band centered on 1 kHz. In order to improve the insertion loss in this band, a slit resonator that makes the wall surface in the propagation path where sound propagates acoustically "soft" is incorporated into the louver blade member 10 of the sound insulation louver 1 according to the present invention. We propose a noise reduction method.

When the wall surface in the propagation path where sound propagates is acoustically "soft", that is, when the acoustic impedance ratio Z on the surface of the wall surface is 0, the noise propagated from the upstream side, which is the sound source side, is reflected to the upstream side. It is known that it does not propagate to the downstream side, which is the sound receiving side.

In the prior art (for example, the techniques described in Japanese Patent No. 3831263 and Japanese Patent No. 5454369), the tube mouth of the acoustic tube is at a frequency equal to 1/4 wavelength and an odd multiple frequency thereof. It is disclosed that the acoustic impedance ratio Z in the above becomes 0.

In contrast to the above-mentioned prior art, the sound insulation louver 1 according to the present invention utilizes a slit resonator 110 in which a resonance phenomenon occurs due to a slit structure having a cavity sealed behind as shown in FIG. FIG. 7 is a diagram illustrating a slit resonator used in the sound insulation louver 1. FIG. 7A is a perspective view of the slit resonator 110. Further, FIG. 7 (B) is a cross-sectional view of the slit-shaped opening 150 of the slit resonator 110 of FIG. 7 (A) as viewed by cutting vertically in the longitudinal direction.

As shown in FIG. 7, the slit resonator 110 used in the sound insulation louver 1 according to the present invention is basically composed of a square columnar housing 140 having a hollow inner space. On one surface of the housing 140 constituting the slit resonator 110, a longitudinal slit-shaped opening 150 and a partition wall arranged on both sides of the slit-shaped opening 150 and extending into the space inside the slit resonator 110. It is characterized by having a part 160 and. Here, each dimension of the slit resonator 110 is represented by a symbol shown in FIG. It should be noted that one surface of the housing 140 in which the slit-shaped opening 150 is formed and the partition wall portion 160 are orthogonal to each other.

When each dimension of the slit resonator 110 is sufficiently small with respect to the wavelength, the acoustic impedance ratio Z in the slit-shaped opening 150 can be obtained by the following equation (1).

ただし、ｆは騒音の周波数、ｃは音速、ρは媒質（空気）密度を表す。また、Ｖ_nは、スリット状開口部１５０と隔壁部１６０とで囲まれた、図２（Ｂ）の斜線部以外の空間の体積で、開口端補正を考慮して次式（２）で計算される。なお、式（２）における[ ]内の第２項が、開口端補正に関連する項である。また、図７（Ｂ）で斜線部の空間は、共鳴器として機能するスリット共鳴器１１０の空気層に相当する。

However, f is the frequency of noise, c is the speed of sound, and ρ is the density of the medium (air). Further, V _n is the volume of the space other than the shaded portion in FIG. 2B surrounded by the slit-shaped opening 150 and the partition wall 160, and is calculated by the following equation (2) in consideration of the opening end correction. Will be done. The second term in [] in the equation (2) is a term related to end correction. Further, in FIG. 7B, the space in the shaded area corresponds to the air layer of the slit resonator 110 that functions as a resonator.

また、Ｖはスリット共鳴器１１０の空洞部の体積（空気層の体積）で、次式（３）で計算される。

Further, V is the volume of the cavity of the slit resonator 110 (volume of the air layer), and is calculated by the following equation (3).

また、Ｓは、スリット状開口部１５０（スリット開口）の面積で、次式（４）で計算される。

Further, S is the area of the slit-shaped opening 150 (slit opening) and is calculated by the following equation (4).

式（１）の右辺第１項のｒは、共鳴器として機能するスリット共鳴器１１０の隔壁部１６０表面と空気の間に生じる摩擦などの音響抵抗である。隔壁部１６０を金属など表面が平滑な材料で構成する場合、音響抵抗ｒは極めて小さな値となり、次式を満足する共鳴周波数ｆにおいてスリット状開口部１５０の開口における音響インピーダンス比Ｚがほぼ０となる。

The first term r on the right side of the equation (1) is an acoustic resistance such as friction generated between the surface of the partition wall 160 of the slit resonator 110 functioning as a resonator and the air. When the partition wall 160 is made of a material having a smooth surface such as metal, the acoustic resistance r becomes an extremely small value, and the acoustic impedance ratio Z at the opening of the slit-shaped opening 150 is almost 0 at the resonance frequency f satisfying the following equation. Become.

このような共鳴器として機能する、２つのスリット共鳴器１１０を、音の伝搬路の壁面５に沿って対向配置すると、上記の周波数ｆにおいては対向するスリット部が音響的に“ソフト”な状態となり、上流側から伝搬してきた周波数ｆの騒音は上流側へ反射され下流側に伝搬しない。

When two slit resonators 110 functioning as such resonators are arranged to face each other along the wall surface 5 of the sound propagation path, the facing slit portions are acoustically "soft" at the above frequency f. Therefore, the noise of frequency f propagating from the upstream side is reflected to the upstream side and does not propagate to the downstream side.

Therefore, in the sound insulation louver 1 according to the present embodiment, the slit resonator 110 as described above is applied. FIG. 8 shows an example of a sound insulation louver incorporating a slit resonator. The opening of the slit-shaped resonator is provided so as to face the ventilation path between the louver blade members. The dimensions of the illustrated resonator aperture are set so that the resonance frequency is about 850 Hz.

As described above, it is ideal to arrange two slit resonators facing each other across the sound propagation path (ventilation path in the louver wall), but due to the structure of the sound insulation louver, one as shown in FIG. The slit resonator was arranged on one side. In this example, the width of the ventilation path between the louver blade members is about 31 mm, which is sufficiently smaller than the wavelength (400 mm) of the slit resonator at the resonance frequency of 850 Hz. You can expect it.

FIG. 6 also shows the numerical calculation result (basic type + resonator) of the insertion loss of the sound insulation louver incorporating the slit resonator shown in FIG.

According to FIG. 6, the insertion loss is greatly improved in the 800 Hz and 1 kHz bands close to the resonance frequency, and the effect of incorporating the slit resonator into the sound insulation louver can be confirmed.

The shape, opening size, and arrangement position of the slit resonator are not limited to the example shown in FIG. Here, an example in which a slit resonator in which the resonance frequency is set to 850 Hz is incorporated is shown from the calculation result of the insertion loss of the basic type shown in FIG. Even for sound insulation louvers with different dimensions, placement intervals, etc., the frequency characteristics of the insertion loss are obtained by numerical calculation or experiment, the resonance frequency of the slit resonator is set according to the band for which the insertion loss is to be improved, and each dimension of the slit resonator. To determine. At this time, the resonance frequency of the slit resonator may be determined in consideration of the frequency characteristics of the target noise.

Even if the slit resonator as described above is incorporated into the louver blade member 10, since the louver blade member is a long body having the same cross section, the effect of cost reduction in manufacturing and construction can be maintained.

1 ... Sound insulation louver 10 ... Louver blade member 11 ... First opening 12 ... Second opening 15 ... Ventilation path 31 ... First straight section 32 ... Second straight section 33 ... 3rd straight line part 34 ... 4th straight line part 40 ... Parabolic part (reflecting part)
50 ... Arc part (reflection part)
60 ... Reinforcing rib 140 ... Housing 110 ... Slit resonator 150 ... Slit-shaped opening 160 ... Partition D ... Focus

Claims (2)

Looking at the cross section in the longitudinal direction,
The first straight part and
A second straight line portion parallel to the first straight line portion and
A plurality of louver blade members having a parabolic portion extending from the second straight portion and a plurality of louver blade members are continuously arranged .
The louver blade member has an arc portion extending from the first straight line portion and has an arc portion.
The focal point formed by the parabolic portion and
A sound insulation louver characterized in that the focal point formed by the arc portion is the same point. The first straight line portion of the louver blade member is
The sound insulation louver according to claim 1, wherein a plurality of the louver blade members are continuously arranged so as to be parallel to the second straight line portion of the other louver blade member.

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