JP2017206938A - Sound insulation louver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sound insulation louver capable of ensuring satisfactory sound insulation performance with a simple structure while reducing the cost accompanying manufacture, transportation and installation.SOLUTION: Disclosed sound insulation louver 1 is a sound insulation louver in which plural louver blade members 10 are successively disposed. In a ventilation path 15 formed between the louver blade members 10, plural reflection parts (parabola part 40, circular arc part 50) are formed. Noises entering at the first opening 11 of the ventilation path 15 is reflected by the plural reflection parts (parabola part 40, circular arc part 50) and goes out from the first opening 11.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a sound insulation louver that can ensure air permeability, has excellent design properties, and can ensure sufficient sound insulation performance.

  When equipment such as an air conditioner outdoor unit is installed on the building roof or on the ground, a blindfold wall is installed to hide the equipment from the surroundings. As the blindfold wall, a louver wall is preferred because of the necessity of ensuring air permeability and design requirements.

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

For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2013-213334) discloses a louver body 11 provided with an opening 13 for inserting the sound absorbing material 50 on the opposite surface of the decorative surface 12, and an opening of the louver body 11. And a sound absorbing louver provided with a cover material 30 covering 13.
JP 2013-213334 A

  A conventional sound absorbing louver is mainly composed of a louver body, a sound absorbing material such as glass wool, and a pressing member for the sound absorbing material, and a member for joining them is also required, resulting in 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 cost due to an increase in man-hours in manufacturing, transportation, and construction in addition to an increase in the cost of the members themselves.

  As described above, the conventional sound absorbing louvers proposed for satisfying the air permeability, the design, and the sound insulation performance have a problem that many of them are expensive due to the complexity of the structure.

  In addition, conventional sound absorption louvers are generally designed to absorb noise effectively at a specific noise incident angle, but noise is generally incident on the louver wall from various directions. There is also a problem in that it may not be possible to ensure sound insulation performance.

  This invention solves the said subject, Comprising: The sound insulation louver which concerns on this invention is a sound insulation louver by which multiple louver blade members are arrange | positioned continuously, Comprising: It forms between the said louver blade members. A plurality of reflecting portions are formed in the ventilation path, and sound incident on the first opening of the ventilation path is reflected by the plurality of reflecting portions and emitted from the first opening. And

  Further, the sound insulation louver according to the present invention has a first straight portion, a second straight portion parallel to the first straight portion, a parabola extending from the second straight portion, as viewed in a cross section with respect to the longitudinal direction, A sound insulating louver characterized in that a plurality of louver blade members having a plurality of louver members are continuously arranged.

  Further, the sound insulation louver according to the present invention is such that the first straight portion of one louver blade member is parallel to the second straight portion of the other louver blade member, A plurality of them are continuously arranged.

  In the sound insulation louver according to the present invention, the louver blade member has an arc portion extending from the first straight portion.

  The sound insulating louver according to the present invention is characterized in that the focal point formed by the parabola part and the focal point formed by the arc part are the same point.

  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 costs associated with an increase in manufacturing, transportation, and construction man-hours can be reduced. Can do.

  In addition, according to the sound insulation louver according to the present invention, it is possible to cope with noise from various directions and to ensure 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 a numerical analysis object. It is a figure which shows the result of a numerical analysis. It is a figure explaining the slit resonator applied to the sound insulation louver. It is a figure which shows the numerical analysis object of the sound insulation louver 1 to which the slit resonator was 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 view showing a louver blade member 10 used in a sound insulation louver 1 according to an 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 FIG. 1 to FIG. 4, the louver blade member 10 and the sound insulation louver 1 are viewed in a 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 configuration of the louver blade member 10 is referred to as a “straight portion” or the like, the actual shape is a plane portion.

  The louver blade member 10 is preferably made of a material having rigidity and large sound transmission loss. For example, aluminum can be used.

  The louver blade member 10 includes a first straight portion 31, a second straight portion 32 parallel to the first straight portion 31, and a parabolic portion 40 extending from the second straight portion 32. The parabola 40 functions as a sound reflector.

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

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

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

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

  As shown in FIG. 2, as long as each louver blade member 10 is fixed, any method for fixing the louver blade member 10 may be used. Further, in the sound insulation louver 1 shown in the figure, the left side is the noise source side where the equipment is 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 adjacent louver blade members 10. The opening of the ventilation path 15 on the noise source side is defined as the first opening 11. The opening of the ventilation path 15 on the sound receiving side is defined as the second opening 12.

  A structure characterizing the sound insulation louver 1 according to the present invention will be described below. First, it has a ventilation path (section A) composed of parallel opposing wall surfaces formed by the first straight part 31 and the second straight part 32.

  Further, as a second characteristic structure of the sound insulating 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 a fourth characteristic structure of the sound insulating louver 1 according to the present invention, the parabolic curved surface (section B) and the circular curved surface (section C) have a 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 the section A, the section B, and the section C from the first opening 11 on the noise source side.

  Next, the principle of reducing noise transmitted through the ventilation path 15 by the sound insulation louver 1 according to the present invention will be described below. 3 and 4 are views for explaining the principle of the sound insulation louver 1 according to the present invention. In the figure, the arrows indicate the direction of noise sound waves.

  In FIG. 3, as shown in (0), noise enters the first opening 11 in 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 through the section A as a plane wave at a frequency where the width of the section A (distance between 31 and 32) is equal to or less than a half wavelength.

  Next, as shown in (2), the sound wave propagating through 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 enters the arcuate curved surface of the section C.

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

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

  Next, as shown in (6), the sound wave reflected by the parabolic curved surface of the section B propagates through 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 transmitted through the ventilation path 15 is reduced by re-radiating the noise propagating through the ventilation path 15 of the sound insulation louver 1 to the noise source side. The sound insulation performance of the louver 1 can be improved.

  Further, according to the sound insulation louver 1 according to the present invention, the only necessary component is the louver blade member 10, which can suppress the number of components and has a simple structure, and therefore costs associated with an increase in manufacturing, transportation, and construction man-hours. Can be reduced.

  Moreover, according to the sound insulation louver 1 which concerns on this invention, it can cope with the noise from various directions, and it becomes possible to ensure 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 insulating louver 1 according to the present invention, since the louver wall can be configured with only the louver blade member 10, the number of members can be reduced and the structure can be simplified.

  In addition, the louver blade member 10 main body is an elongated body having the same cross-sectional view. 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, it can be expected to reduce the construction cost.

  Here, in the sound insulation louver 1 according to the present embodiment described above, the sound wave incident on the first opening 11 is converted into a plane wave in the section A, and is reflected by the parabolic curved surface of the section B including the parabolic portion 40. First, after passing through the focal point D, it is converged again toward the focal point D by the circular curved surface of the section C formed by the circular arc portion 50, and further reflected by the parabolic curved surface of the section B formed by the parabolic portion 40, Although the section A is propagated as a plane wave and emitted to the first opening 11 on the noise source side, 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 converts the incident sound wave from the first opening 11 of the sound insulation louver 1 into a plane wave, reflects it with a plurality of reflection portions in the ventilation path 15, and again causes a noise source from the first opening 11. If it is the structure of radiating | emitting to the side, it will not be limited to the reflection part which consists of a parabolic curved surface, an arc curved surface, etc. which were demonstrated in embodiment.

  That is, the sound insulation louver 1 according to the present invention is characterized in that the sound wave incident from the first opening 11 of the sound insulation louver 1 is emitted from the first opening 11 again by giving the shape of the ventilation path 15 a characteristic. It includes all thoughts.

  In addition, the sound insulation louver 1 according to the present invention is characterized in that a sound wave focal point is formed in the ventilation path 15 by giving the shape to the shape in the ventilation path 15 and the sound insulation is achieved by utilizing this focus. Is also included. Although there is a demerit that the number of parts increases, for example, a sound absorbing material is arranged at the focal point D in the embodiment, and sound absorption at the focal point D is also included in the sound insulating louver 1 according to the present invention. .

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

  In the following numerical calculations, the two-dimensional boundary element method was used. The calculation target is a louver wall in which louver blade members are arranged at a predetermined interval. 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 being completely reflective. As the sound source, a point sound source was placed at a position 2 m away from the louver wall on the left side in the drawing, and the acoustic energy transmitted to the sound receiving side (right side in the drawing) of the louver wall was obtained by calculation.

  The sound source side space and the sound receiving side space are connected by an opening having a height of 1.3 m, and a louver wall is disposed in the opening. As a comparison object, the acoustic energy transmitted through a simple opening where no louver wall is disposed is obtained by calculation, and the amount of acoustic energy reduced by the presence or absence of the louver wall is evaluated as the insertion loss of the sound insulation louver, that is, the noise reduction performance.

  In the numerical calculation, it is performed for a pure tone every 1/15 octave, and the obtained acoustic energy that is transmitted to the sound receiving side is averaged five times centering on the center frequency of the 1/3 octave band, so that 1/3 is obtained. The calculation result was an octave band. From the obtained calculation results, the amount of acoustic energy reduced by the louver wall with the simple opening as a reference was calculated as described above, and the insertion loss of the sound insulation louver was calculated.

  FIG. 6 shows the frequency characteristics of the insertion loss of the sound insulation louver shown in FIG. Higher values indicate higher noise reduction performance. In order to distinguish from the case where a slit resonator described later is incorporated, the result based on the sound insulation louver shown in FIG. 5 is referred to as a “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 a band centered at 1 kHz. This measure is proposed below.

  As described above, the basic sound insulation louver has a low insertion loss in a band centered at 1 kHz. In order to improve the insertion loss in this band, a slit resonator that acoustically “softens” the wall surface in the propagation path through which sound propagates is incorporated into the louver blade member 10 of the sound insulation louver 1 according to the present invention. A noise reduction method is proposed.

  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 that is the sound source side is reflected upstream It is known that it does not propagate to the downstream side that is the sound receiving side.

  In the conventional technology (for example, the technology described in Japanese Patent No. 383263 and Japanese Patent No. 5454369), the tube of the acoustic tube has a frequency at which the tube length of the acoustic tube is equal to a quarter wavelength and an odd multiple thereof. It is disclosed that the acoustic impedance ratio Z becomes zero.

  In contrast to the conventional technology as described above, the sound insulation louver 1 according to the present invention uses a slit resonator 110 in which a resonance phenomenon occurs due to a slit structure having a sealed cavity 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. FIG. 7B is a cross-sectional view of the slit-shaped opening 150 of the slit resonator 110 of FIG.

  As shown in FIG. 7, the slit resonator 110 used in the sound insulation louver 1 according to the present invention basically includes a quadrangular prism-shaped housing 140 whose inner space is hollow. On one surface of the housing 140 constituting the slit resonator 110, a long slit-shaped opening 150, and a partition wall that is disposed on both sides of the slit-shaped opening 150 and extends into a space inside the slit resonator 110. Part 160. Here, each dimension of the slit resonator 110 is represented by a symbol shown in FIG. Note that one surface of the housing 140 in which the slit-shaped opening 150 is formed and the partition wall 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).

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

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

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

  R in the first term on the right side of 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 has a very small value, and the acoustic impedance ratio Z at the opening of the slit-shaped opening 150 is substantially 0 at the resonance frequency f satisfying the following equation. Become.

  When the two slit resonators 110 functioning as such resonators are disposed opposite to each other along the wall surface 5 of the sound propagation path, the opposing slit portions are acoustically “soft” at the frequency f. Thus, the noise having the frequency f propagated from the upstream side is reflected upstream and does not propagate downstream.

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

  As described above, it is ideal that the two slit resonators are opposed to each other across the sound propagation path (the ventilation path in the louver wall), but due to the structure of the sound insulation louver, one slit 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) at the resonance frequency of 850 Hz of the slit resonator. I can expect.

  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 is shown in which a slit resonator having a resonance frequency set to 850 Hz is incorporated from the calculation result of the basic type insertion loss shown in FIG. Even in sound insulation louvers with different dimensions and arrangement intervals, the frequency characteristics of insertion loss are obtained by numerical calculation or experiment, and the resonance frequency of the slit resonator is set according to the band where the insertion loss is to be improved. To decide. 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 in 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.

DESCRIPTION OF SYMBOLS 1 ... Sound insulation louver 10 ... Louver blade member 11 ... 1st opening 12 ... 2nd opening 15 ... Ventilation path 31 ... 1st linear part 32 ... 2nd linear part 33 ... 3rd straight line part 34 ... 4th straight line part 40 ... Parabolic part (reflection part)
50 ... Circular arc part (reflection part)
60 ... Reinforcing rib 140 ... Case 110 ... Slit resonator 150 ... Slit-shaped opening 160 ... Partition wall D ... Focus

Claims (5)

The louver blade member is a sound insulation louver arranged in a plurality of consecutively,
In the ventilation path formed between the louver blade members, a plurality of reflective portions are formed,
The sound insulation louver is characterized in that sound incident on the first opening of the ventilation path is reflected by the plurality of reflecting portions and emitted from the first opening. Looking at the cross section for the longitudinal direction,
A first straight portion;
A second straight portion parallel to the first straight portion;
A sound insulating louver, wherein a plurality of louver blade members having a parabolic portion extending from the second straight portion are continuously arranged. The first straight portion of the one louver blade member is
The sound-insulating louver according to claim 2, wherein a plurality of the louver blade members are continuously arranged so as to be parallel to the second linear portion of the other louver blade member. The sound insulation louver according to claim 2 or 3, wherein the louver blade member has an arc portion extending from the first straight portion. A focal point formed by the parabola,
The sound insulating louver according to claim 4, wherein the focal point formed by the arc portion is the same point.

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