JP2017101530A - Noise reduction structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noise reduction structure for a ventilation opening of a building, which can reduce the types and number of component members, and which can achieve simplification of a structure and the miniaturization and weight reduction of a device.SOLUTION: In a noise reduction device 1 according to the present invention, a resonator 10 having a slit-like opening 50 is arranged on a wall surface of an interior wall of an opening 100 of a building.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a noise reduction structure that reduces noise from a ventilation opening of a building.

  In a sound field that propagates one-dimensionally, such as low-frequency noise that propagates through a duct, etc., by placing an acoustic tube on the wall surface of the duct, the noise that propagates further downstream, that is, the noise exit side is reduced. A method is proposed in Patent Document 1, Patent Document 2, and the like.

In the methods described in Patent Document 1 and Patent Document 2, a noise reduction effect can be obtained at a frequency at which the tube length of the acoustic tube is equal to 1/4 of the wavelength and a frequency that is an odd multiple thereof.
Japanese Patent No. 3832633 Japanese Patent No. 5454369

  By the way, in order to reduce the energy consumption of a building, a ventilation system that naturally introduces outside air by providing an opening in the outer wall of the building may be employed. An example of the ventilation opening 100 provided between the exterior wall 120 and the interior wall 110 of the building is shown in FIG.

  One of the problems of the natural ventilation system is that the outdoor noise propagates into the room through the opening in the ventilation opening 100 as described above, so that the level of the room noise rises and the silence cannot be secured.

  A noise countermeasure method may be employed in which the outside air introduction path in the ventilation opening 100, that is, the noise propagation path, is subjected to sound absorption processing. However, although the sound absorbing material is generally effective for high frequencies, a large effect cannot be expected for low frequencies.

  Therefore, it is conceivable to apply the techniques described in Patent Document 1 and Patent Document 2 to the ventilation opening 100.

According to the technique described in Patent Document 1, when it is desired to obtain a noise reduction effect with respect to noise having a low frequency, that is, noise having a long wavelength, an acoustic tube having a long tube length is required, and the noise reduction structure is enlarged. In Patent Document 2, an attempt is made to downsize the device by bending a long acoustic tube, but this makes the structure complicated and increases the types and number of components. A problem will occur. Such a problem becomes particularly noticeable in an apparatus in which acoustic tubes having different lengths are combined in order to obtain a noise reduction effect in a wide frequency range.

  According to the noise reduction structure in the ventilation opening 100 according to the methods described in Patent Document 1 and Patent Document 2, a large number of partition plates are required to configure a large number of acoustic tubes having a rectangular cross section, and this is also the structure. This complicates and increases the weight of the entire apparatus. As described above, the noise reduction structure in the ventilation opening 100 described in Patent Document 1 and Patent Document 2 has various structures such as a complicated structure, a large number of types and number of constituent members, weight of the apparatus, and an increase in manufacturing and assembly costs. There was a problem.

  This invention solves the said subject, The noise reduction structure which concerns on this invention is characterized by the resonator which has a slit-shaped opening part being distribute | arranged to the wall surface in the inner wall of the opening part of a building, It is characterized by the above-mentioned. To do.

  The noise reduction structure according to the present invention is characterized in that a resonator having a slit-like opening is arranged in a space between an interior wall and an exterior wall in an opening of a building.

  Moreover, the noise reduction structure according to the present invention is characterized in that a resonator having a slit-like opening is arranged on an interior wall provided with an opening of a building.

  Moreover, the noise reduction structure according to the present invention is characterized in that a resonator having a slit-like opening is arranged on a wall surface of an inner wall of an opening of a bent building.

  Moreover, the noise reduction structure according to the present invention is characterized in that the resonators are arranged in pairs so that the slit-shaped openings face each other.

  In the noise reduction structure according to the present invention, the resonator is divided into a plurality of sections by a partition plate member.

  Moreover, the noise reduction structure according to the present invention is characterized in that the resonator includes a box-shaped outer shell member whose one surface is an opening surface, and an L-shaped member.

  The noise reduction structure according to the present invention is characterized in that the resonator includes a box-shaped outer shell member having an opening surface on one side, an L-shaped member, and a partition plate member.

  The noise reduction structure according to the present invention is characterized in that the resonator has an air layer.

  Moreover, the noise reduction structure according to the present invention is characterized in that the resonator does not have an air layer.

  In the noise reduction structure according to the present invention, a resonator having a slit-shaped opening with an acoustic impedance ratio of 0 is disposed, for example, on the wall surface of the inner wall of the opening of a building. According to the noise reduction structure, the type and number of components can be reduced as the noise reduction structure in the ventilation opening 100, and the structure can be simplified, the apparatus can be reduced in size, and the weight can be reduced. In addition, assembly costs can be reduced.

It is a figure which shows the opening part 100 for ventilation to which the noise reduction structure 1 which concerns on embodiment of this invention is applied. It is a figure explaining the principle of the noise reduction structure 1 which concerns on embodiment of this invention. It is a figure explaining the resonator 10 used for the noise reduction structure 1 which concerns on embodiment of this invention. It is a figure which shows the example of application to the opening part 100 for ventilation of the noise reduction structure 1 which concerns on embodiment of this invention. It is a figure explaining the example of a manufacturing process of the resonator 10 used for the noise reduction structure 1 which concerns on embodiment of this invention. It is a figure which shows the example of application to the opening part 100 for ventilation of the noise reduction structure 1 which concerns on other embodiment of this invention. It is a figure which shows the example of application to the opening part 100 for ventilation of the noise reduction structure 1 which concerns on other embodiment of this invention. It is a figure which shows the opening part 100 for ventilation which has the bending ventilation path 130. FIG. It is a figure which shows the example of application to the opening part 100 for ventilation of the noise reduction structure 1 which concerns on other embodiment of this invention. It is a figure which shows the example of application to the opening part 100 for ventilation of the noise reduction structure 1 which concerns on other embodiment of this invention. It is a figure which shows the example of application to the opening part 100 for ventilation of the noise reduction structure 1 which concerns on other embodiment of this invention. It is a figure explaining the resonator 10 used for the noise reduction structure 1 which concerns on other embodiment of this invention. It is sectional drawing at the time of applying the noise reduction apparatus 1 which concerns on other embodiment of this invention to the opening part 100 for ventilation. It is sectional drawing at the time of applying the noise reduction apparatus 1 which concerns on other embodiment of this invention to the opening part 100 for ventilation. 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 resonator 10 used for the noise reduction structure 1 which concerns on other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the principle of the noise reduction method employed by the noise reduction structure 1 according to the present invention will be described. FIG. 1 is a view showing a ventilation opening 100 to which a noise reduction structure 1 according to an embodiment of the present invention is applied. FIG. 2 is a diagram illustrating the principle of the noise reduction structure 1 according to the embodiment of the present invention. FIG. 2 is a view showing only the inner wall extracted from the ventilation opening 100.

  When noise propagates through the inside of a duct such as the ventilation opening 100, the noise cross section is less than half of the noise wavelength when the dimensional cross section of the ventilation opening 100 (the plane perpendicular to the noise propagation direction) is less than half. Propagates one-dimensionally as a plane wave in the pipe.

  FIG. 2 is a perspective view of the inner wall of the ventilation opening 100. Hereinafter, in the ventilation opening 100 according to the embodiment of the present specification, there is a noise source on the upstream side (outdoor side outside the building), and noise from the noise source is downstream (inside and outside the building). An example will be described in which it is propagated to. Although the description will be made on the assumption that the longitudinal direction of the ventilation opening 100 is installed in the horizontal direction, the installation method of the ventilation opening 100 is not limited to such an example.

  In this ventilating opening 100, the four inner walls 105 forming the ventilating opening 100 are assumed to be normal wall surfaces, and the two inner walls 105 facing vertically in the perspective view are acoustically “soft”. Assuming that

  As shown in FIG. 1, noise propagated from the upstream side when the opposing wall surface inside the ventilation opening 100 is acoustically “soft”, that is, when the acoustic impedance ratio Z at the surface of the wall surface is 0. Is known to be reflected upstream and not propagate downstream.

  In the present embodiment, the description is based on an example in which two opposing wall surfaces having an acoustic impedance ratio Z on the surface of 0 face each other in the vertical direction. However, the acoustic impedance ratio Z on the surface is 0. Two opposing wall surfaces may be opposed in the horizontal direction.

  The existing technology (the technology described in Patent Document 1 and Patent Document 2) is a frequency at which the tube length of the acoustic tube is equal to a quarter wavelength and an odd multiple thereof, and the acoustic impedance ratio Z at the tube mouth of the acoustic tube is Utilizing that it becomes zero.

  In the noise reduction structure 1 according to the present invention, a resonator 10 in which a resonance phenomenon occurs due to a slit structure having a sealed cavity shown in FIG. 3 is used. FIG. 3A is a perspective view of the resonator 10. FIG. 3B is a cross-sectional view of the slit-shaped opening 50 of the resonator 10 of FIG.

  As shown in FIG. 3, the resonator 10 used in the noise reduction structure 1 according to the present invention is basically composed of a quadrangular prism-shaped housing 40 whose inner space is hollow. On one surface of the casing 40 constituting the resonator 10, a longitudinal slit-shaped opening 50, and a partition wall 60 that is disposed on both sides of the slit-shaped opening 50 and extends to a space inside the resonator 10. It is characterized by having. Here, each dimension of the resonator 10 functioning as a resonator is represented by a symbol shown in FIG. Note that the one surface of the housing 40 in which the slit-shaped opening 50 is formed and the partition wall 60 are orthogonal to each other.

  When each dimension of the resonator 10 is sufficiently small with respect to the wavelength, the acoustic impedance ratio Z in the slit-shaped opening 50 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５０と隔壁部６０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３（Ｂ）で斜線部の空間は、共鳴器として機能する共鳴器１０の空気層に相当する。

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 50 and the partition wall 60 except for 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. In FIG. 3B, the hatched space corresponds to the air layer of the resonator 10 that functions as a resonator.

また、Ｖは共鳴器１０の空洞部の体積（空気層の体積）で、次式（３）で計算される。

V is the volume of the cavity of the resonator 10 (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５０（スリット開口）の面積で、次式（４）で計算される。

S is the area of the slit-like opening 50 (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共鳴器１０の隔壁部６０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６０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５０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。

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 60 of the resonator 10 functioning as a resonator and the air. When the partition wall 60 is made of a material having a smooth surface such as a metal, the acoustic resistance r has an extremely small value, and the acoustic impedance ratio Z at the opening of the slit-shaped opening 50 is substantially 0 at the resonance frequency f that satisfies the following equation. Become.

このような共鳴器として機能する、２つの共鳴器１０を、図４に示すように、換気用開口部１００の上下の内壁１０５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 the two resonators 10 functioning as such resonators are disposed to face each other along the upper and lower inner walls 105 of the ventilation opening 100 as shown in FIG. 4, the slit slits facing each other at the frequency f described above. The portion becomes acoustically “soft”, and the noise of the frequency f propagated from the upstream side is reflected upstream and does not propagate downstream.

  FIG. 4 is a diagram illustrating an application example of the noise reduction structure 1 according to the embodiment of the present invention to the ventilation opening 100. 4A is a perspective view of the noise reduction structure 1, and the noise reduction structure 1 of FIG. 4B is perpendicular to the longitudinal direction of the ventilation opening 100 (or the longitudinal direction of the slit-like opening 50). It is sectional drawing seen by cutting in.

  According to the noise reduction structure 1 of the ventilation opening 100 as shown in FIG. 4, the acoustic impedance ratio at the slit-like opening 50 of the resonator 10 facing the resonance frequency of the resonator 10 becomes almost 0 at the resonance frequency of the resonator 10. Noise incident from the (upstream side) is reflected to the outdoor side and does not propagate to the indoor side (downstream side).

  Next, the manufacturing process of the resonator 10 constituting the noise reduction structure 1 will be described. FIG. 5 is a diagram illustrating an example of a manufacturing process of the resonator 10 used in the noise reduction structure 1 according to the embodiment of the present invention.

  The outer shell member 20 is a rectangular parallelepiped box-shaped member in which one of the six surfaces is an opening surface 25. The L-shaped member 30 is a member having an L-shaped cross section and two surfaces that are orthogonal to each other.

  As shown in FIG. 5, the resonator 10 can be manufactured by attaching two L-shaped members 30 as described above to the opening surface 25 of the outer shell member 20.

  A space between the two L-shaped members 30 attached to the opening surface 25 of the outer shell member 20 is a slit-shaped opening 50. In addition, one of the two surfaces of the L-shaped member 30 functions as the partition wall 60 of the resonator 10.

  In the manufacturing method of the resonator 10 as described above, the noise reduction structure 1 that can easily change the frequency to be reduced is configured by preparing the outer shell member 20 and the L-shaped member 30 of various dimensions in advance. It becomes possible to do.

  As described above, in the noise reduction structure 1 according to the present invention, the resonator 10 having the slit-shaped opening 50 with an acoustic impedance ratio of 0 is formed on the wall surface on the inner wall of the ventilation opening 100 of the building. Since the parts 50 are arranged in pairs so as to face each other, according to the noise reduction structure 1 according to the present invention, the type and number of constituent members can be reduced as the noise reduction structure 1 in the ventilation opening 100. In addition, it is possible to simplify the structure, reduce the size and weight of the apparatus, and suppress the manufacturing and assembly costs.

  Next, another embodiment of the present invention will be described. FIG. 6 is a diagram showing an application example of the noise reduction structure 1 according to another embodiment of the present invention to the ventilation opening 100. It is sectional drawing which looked at the noise reduction structure 1 of FIG. 6 by cut | disconnecting the longitudinal direction of the opening part 100 for ventilation (or the longitudinal direction of the slit-shaped opening part 50) perpendicularly | vertically.

  In the present embodiment, as shown in FIG. 6, the slit-shaped openings 50 of the two resonators 10 face each other in the space between the interior wall 110 and the exterior wall 120 in the ventilation opening 100 of the building. The resonators 10 are arranged in pairs.

  According to such embodiment, while being able to enjoy the same effect as previous embodiment, it becomes possible to use effectively the space between interior wall 110 and exterior wall 120.

  Next, another embodiment of the present invention will be described. FIG. 7 is a diagram showing an application example of the noise reduction structure 1 according to another embodiment of the present invention to the ventilation opening 100. It is sectional drawing which looked at the noise reduction structure 1 of FIG. 7 by cut | disconnecting the longitudinal direction of the opening part 100 for ventilation (or the longitudinal direction of the slit-shaped opening part 50) perpendicularly | vertically.

  In the present embodiment, as shown in FIG. 7, the slits 50 of the two resonators 10 are opposed to each other on the upper and lower sides of the interior wall 110 provided with the ventilation opening 100 of the building. The resonator 10 is arranged.

  According to such an embodiment, the same effect as the previous embodiment can be enjoyed, and since the two resonators 10 are attached to the interior wall 110, the existing noise reduction measures are not taken. The noise reduction structure 1 can be added later to the ventilation opening.

  Next, another embodiment of the present invention will be described. The noise reduction structure 1 according to the present embodiment is applied to a ventilation opening 100 having a bent ventilation path 130 as shown in FIG.

   In the ventilation system using the ventilation opening 100 that naturally introduces outside air, the outside air introduction path that continues from the opening of the exterior wall 120 is bent by the bent ventilation path 130 so that the outside air is blown upward or downward into the room. It is.

  The ventilation system using the ventilation opening 100 having the bent ventilation path 130 may be a pattern such as a blowout from the floor, a blowout from the ceiling, or a blowout from the top of the counter near the wall or window. .

  FIG. 8 is a ventilation opening 100 that blows out from the upper surface of the counter at the wall, and is a diagram schematically showing a cross section of a bent outside air introduction path.

  FIG. 9 is a diagram showing an application example of the noise reduction structure 1 according to another embodiment of the present invention to the ventilation opening 100. The ventilation opening 100 is assumed to have the bent ventilation path 130 shown in FIG. It is sectional drawing which looked at the noise reduction structure 1 of FIG. 9 by cut | disconnecting the longitudinal direction of the opening part 100 for ventilation (or the longitudinal direction of the slit-shaped opening part 50) perpendicularly | vertically.

  In the present embodiment, the resonators 10 are arranged in pairs such that the slit-like openings 50 of the two resonators 10 face the wall surface of the inner wall 105 of the ventilation opening 100 having the bent ventilation path 130. I have to.

  According to such an embodiment, the same effect as that of the previous embodiment can be obtained for the ventilation opening 100 having the bent ventilation path 130.

  Next, another embodiment of the present invention will be described. FIG. 10 is a diagram showing an application example of the noise reduction structure 1 according to another embodiment of the present invention to the opening 100 for ventilation. FIG. 10 is a combination of the two resonators 10 and the sound absorbing material 150 by further adding the sound absorbing material 150 to the embodiment shown in FIG. 9.

  As described above, when the sound absorption process is performed on a part of the outside air introduction path of the ventilation opening 100, the high frequency component of the noise can be reduced from the sound absorbing material 150, so that the resonance frequency of the resonator 10 is the sound absorbing material. By designing the frequency so that it is difficult to obtain the effect of 150, a noise reduction effect for a wide frequency band can be expected by complementing both.

  Next, another embodiment of the present invention will be described. FIG. 11 is a diagram showing an application example of the noise reduction structure 1 according to another embodiment of the present invention to the opening 100 for ventilation. It is sectional drawing which looked at the noise reduction structure 1 of FIG. 11 by cut | disconnecting the longitudinal direction of the opening part 100 for ventilation (or the longitudinal direction of the slit-shaped opening part 50) perpendicularly | vertically.

  In the embodiment shown in FIG. 11, three partition plate members 70 are further provided in the embodiment shown in FIG. 4, and the resonator 10 is arranged in the first compartment 11, the second compartment 12, the third compartment 13, and the fourth compartment 14. It is divided into four sections. Here, in this embodiment, the resonator 10 is divided into four sections, but the number of sections into which the resonator 10 is divided is arbitrary. In addition, the partitioning of the resonator 10 by providing such a partition plate member 70 can be applied to other than the embodiment shown in FIG.

  When the opening of the ventilation opening 100 is provided on the wall surface in the longitudinal direction in the horizontal direction, especially in a situation where noise from the outside is incident obliquely in the horizontal direction with respect to the wall surface, the ventilation opening 100 path It is also conceivable not to propagate in one dimension.

  In such a case, as shown in FIG. 11, by providing a partition plate member 70 in the opening and the resonator 10 to be incorporated, noise propagates in the ventilation opening 100 one-dimensionally and the resonator 10. The noise reduction device by shows the effect.

  In addition, it is preferable that the space | interval which provides the partition plate member 70 shall be 1/2 or less of the wavelength of the noise to reduce.

  Further, when the noise to be reduced by the noise reduction structure 1 has a plurality of peak frequencies in the frequency characteristics or a frequency component in a wide band, the interval between the partition plate members 70 and the like is In another preferred embodiment, the resonator 10 is set differently and provided with sections having different lengths in the horizontal direction.

  As described above, in the noise reduction structure according to the present invention, a resonator having a slit portion with an acoustic impedance ratio of 0 is set so that, for example, the slit-like opening portion faces the wall surface of the ventilation opening portion of the building. Therefore, according to such a noise reduction structure according to the present invention, the type and number of components can be reduced as the noise reduction structure in the ventilation opening 100, the structure is simplified, and the apparatus is downsized. Thus, it is possible to reduce the weight and to suppress the manufacturing and assembly costs.

  Next, another embodiment of the present invention will be described. The noise reduction device 1 according to the embodiment described so far exhibits a noise reduction effect at the resonance frequency f determined by the equation (5). The resonance frequency f can be adjusted to the frequency characteristics of noise by adjusting the dimensions A, B, C, a, and l shown in FIG.

  However, when the target noise to be reduced by the noise reduction device 1 has a plurality of peak frequencies in the frequency characteristics or has frequency components in a wide band, the resonators 10 having different resonance frequencies are combined. There is a need.

  Therefore, in the noise reduction structure 1 according to another embodiment, a device having a plurality of resonance frequencies is configured with simple and few members. More specifically, in the noise reduction structure 1 according to the present embodiment, the resonator 10 has a rectangular parallelepiped outer shell member 20 (one of which has already been described) whose one surface is open, and a single plate-like shape. It is comprised by the partition plate member 35 and the L-shaped member 30 (similar to what was already demonstrated) from which a dimension differs.

  FIG. 12 is a diagram illustrating a resonator 10 used in a noise reduction structure 1 according to another embodiment of the present invention.

  FIG. 12A is an exploded perspective view of the noise reduction structure 1 according to another embodiment. FIG. 12B is a perspective view of the noise reduction structure 1 according to another embodiment. FIG. 12C shows the ventilation opening 100 to which the noise reduction structure 1 is attached in the other embodiment in the longitudinal direction of the ventilation opening 100 (or the longitudinal direction of the slit-like opening 50). It is sectional drawing seen perpendicularly.

  As shown in FIGS. 12A and 12B, two L-shaped members 30 as described above and one partition plate member 35 are attached to the opening surface 25 of the outer shell member 20. The resonator 10 can be manufactured. In this case, the partition plate member 35 also functions as the partition wall portion 60.

As shown in FIG. 12, by combining the outer shell member 20, the L-shaped member 30, and the partition plate member 35, two slit resonators having the space A and the space B can be configured in one resonator. . In each resonator, the acoustic impedance ratio Z of the slit portion 50 becomes substantially zero at the respective resonance frequencies f ₁ and f ₂ , and these are opposed to the wall surface of the ventilation opening 100 as shown in FIG. By arranging it, the noise reduction effect is exhibited for a plurality of frequencies.

  The noise reduction structure 1 according to another embodiment as described above can be variously used by using the outer shell member 20 and the partition plate member 35 having the same dimensions as long as the position of the partition plate member 35 and the dimension of the L-shaped member 30 are changed. A resonator 10 having a resonance frequency can be configured.

  Note that the “space” such as the space A and the space B is underlined in the drawing.

  FIG. 13 is a cross-sectional view when the noise reduction structure 1 according to another embodiment of the present invention is applied to the ventilation opening 100. FIG. 13 is a cross-sectional view of the ventilation opening 100 as viewed from the longitudinal direction (or the longitudinal direction of the slit-shaped opening 50).

  As shown in FIG. 13, if the number of partition plate members 35 and L-shaped members 30 is increased, three slit resonators having a space A, a space B, and a space C can be formed, and one outer shell member 20 is formed. It is possible to construct a resonator 10 having three or more different resonance frequencies. In this case, the partition plate member 35 also functions as the partition wall portion 60.

  Moreover, FIG. 14 is sectional drawing at the time of applying the noise reduction structure 1 which concerns on other embodiment of this invention to the opening part 100 for ventilation. FIG. 14 is a cross-sectional view of the ventilation opening 100 as viewed from the longitudinal direction (or the longitudinal direction of the slit-like opening 50) cut perpendicularly.

In the noise reducing structure 1 according to another embodiment of FIG. 14, the resonator 10 is two resonators consisting of the space A and the space C is separated by the partition plate member 35 of the two spaced intervals a _t construction It has become. In this case, the slit between the two resonators becomes a slit-like opening 50 having no air layer behind. In this case, the partition plate member 35 also functions as the partition wall portion 60.

When facing placed along such a resonator 10 on the inner wall of the ventilation opening 100, with respect to the frequency interval a _t the cross-sectional dimensions and the partition plate member 35 of the ventilation opening 100 is equal to or less than a half wavelength, The slit-shaped opening 50 having no air layer behind functions as an acoustic tube (space B).

In this case, the dimension D of the outer shell member 20 corresponds to the pipe length of the acoustic tube, in the frequency f _t and its odd multiples of a frequency 1/4 is equal to D of wavelength, acoustic slit opening 50 of the acoustic tube Impedance ratio Z becomes 0 and the noise reduction effect is exhibited.

In general, the above-mentioned f _t is higher than the resonance frequency f ₁ or f ₂ of the slit resonator (space A and space C in FIG. 13), and therefore a structure in which the slit resonator and the acoustic tube are combined as shown in FIG. The noise reduction structure 1 using the resonator 10 can exhibit a noise reduction effect over a wide range of frequencies.

Incidentally, Again, spacing a _t the cross-sectional dimensions and the partition plate of the ventilation openings is for frequencies equal to or less than the half wavelength, the slit having no air layer behind serves as an acoustic tube. The prior art described in Patent Literature 1 and Patent Literature 2 requires a large number of partition plates in order to form an acoustic “tube” having a rectangular cross section. On the other hand, in the present invention, these partition plates are unnecessary.

  Since the effect of the noise reduction structure 1 according to the present invention was confirmed by numerical analysis, the results are shown below. FIG. 15 is a diagram showing the object of numerical analysis. In any of FIGS. 15A to 15C, the case of the present invention in which the resonator 10 is installed on the left side, and the resonator is not installed on the right side. Shows the case.

  Further, in the noise reduction structure 1 according to the present invention, FIG. 15A shows a case where the resonator 10 is “one-sided”, FIG. 15B shows a case where the resonator 10 is “opposed”, FIG. 15C shows a case where the resonators 10 are “one-sided parallel arrangement”.

  As a numerical analysis method, a two-dimensional boundary element method was used. The analysis target was assumed to be a ventilation opening 100 having a width of 100 mm provided on an infinite wall surface having a thickness of 300 mm. As shown in FIG. 15A, a plane sound wave was incident from the outdoor side, and the acoustic energy passing through the virtual plane indicated by the broken line in the figure in the indoor side direction was obtained by calculation.

  The resonator 10 which is the noise reduction structure 1 is added to the indoor side of the ventilation opening 100. In addition to FIG. 15 (B) arranged opposite to each other, the resonator 10 is installed in FIG. 15 (A) in which one resonator 10 is arranged on one side for comparison, and two resonators 10 are arranged in parallel on one side. It was set as FIG.

  The dimensions of the resonator 10 constituting the noise reduction structure 1 were B = 100, C = 150, a = 50, l = 40 (unit mm). For the two-dimensional analysis, the longitudinal dimension in the depth direction in FIG. 15 is A = ∞.

  Sound that passes through the virtual plane in the indoor side direction under the condition in which the resonator 10 constituting the noise reduction structure 1 is arranged on the condition that the resonator shown on the right side of FIGS. 15A to 15C is not installed. The amount of energy reduction, that is, the installation effect of the resonator 10 was obtained.

  The analysis is performed on a pure tone every 1/27 octave, and the acoustic energy passing through the obtained virtual plane in the indoor side direction is averaged nine times centering on the center frequency of 1/3 octave band, so that 1/3 It was set as the analysis result in an octave band. In each arrangement method of “one-sided arrangement” (FIG. 15A), “opposing arrangement” (FIG. 15B), and “one-sided parallel arrangement” (FIG. 15C), depending on the presence or absence of a resonator as described above. The reduction amount of the acoustic energy passing through the virtual plane in the indoor side direction was obtained and used as the effect of the resonator in the 1/3 octave band.

  In addition, the length of the opening 100 for ventilation in each arrangement | positioning method is made the same in both conditions with / without a resonator. This includes the effect of changing the length of the ventilation opening on the installation effect of the resonator calculated in the above procedure when the length of the ventilation opening changes under each condition with and without the resonator. It is because it will be.

  FIG. 16 shows the frequency characteristics of the effect of the resonator 10 in “one side arrangement”, “opposite arrangement”, and “one side parallel arrangement”. It can be confirmed that the noise reduction effect is obtained mainly in the 400 Hz band close to the resonance frequency under any arrangement condition.

  Compared with the “one-sided arrangement”, the “opposite arrangement” is more effective in a frequency band where a positive noise reduction effect centered on the resonance frequency is obtained.

  “One-sided parallel arrangement” uses two resonators as in the “opposite arrangement”. In the 400 Hz band close to the resonance frequency, the effect obtained compared with “opposing arrangement” is large, but the effect is small on the high frequency side. In addition, a stable noise reduction effect cannot be obtained as a whole of the frequency characteristics, for example, the effect is greatly reduced on the low frequency side of the resonance frequency. As described above, it can be confirmed that the “opposite arrangement” can obtain a stable effect in a wide frequency band as compared with the “one side parallel arrangement”.

  From the above results, it can be confirmed that the method of “facing the resonators 10” with respect to the resonator 10 is more effective as a noise reduction method than other methods of placement, but “one-sided placement”, “one-sided parallel placement”, etc. It can be seen that a sufficient noise reduction effect can also be expected in the arrangement method. If only “one-sided arrangement” or “one-sided parallel arrangement” can be adopted due to layout and the like, such an arrangement can also be adopted as appropriate.

  Next, another embodiment of the present invention will be described. FIG. 17 is a diagram illustrating a resonator 10 used in a noise reduction structure 1 according to another embodiment of the present invention. FIG. 17A shows the resonator 10 used in the noise reduction structure 1 according to the embodiment described so far, and FIG. 17B shows the resonator 10 used in the noise reduction structure 1 according to this embodiment. Show. The noise reduction structure 1 according to this embodiment is characterized in that the resonator 10 shown in FIG. 17B is arranged in the ventilation opening 100.

  As shown in FIG. 17A, the resonator 10 of the noise reduction structure 1 according to the embodiment described so far is arranged on both sides of the slit portion 50 and provided with partition walls 60. These partition walls 60 are It had a length of 1 in the depth direction.

  On the other hand, the resonator 10 of the noise reduction structure 1 in the present embodiment shown in FIG. 17B has a structure in which the partition walls 60 on both sides of the slit part 50 are omitted. Although the partition wall portion 60 is omitted, the plate thickness of the front surface of the resonator 10 including at least the slit portion 50 has a thickness of 1 instead.

With the plate thickness l, V _n described in the first embodiment is generated also in the resonator 10 used in the present embodiment. As a result, even with the noise reduction structure 1 according to the present embodiment in which the resonator 10 in which the partition wall portion 60 is omitted is used, it is possible to receive the same effects as the noise reduction structure 1 described so far.

DESCRIPTION OF SYMBOLS 1 ... Noise reduction structure 10 ... Resonator 11 ... 1st division 12 ... 2nd division 13 ... 3rd division 14 ... 4th division 20 ... Outer shell member 25- .... Opening surface 30 ... L-shaped member 35 ... Partition plate member 40 ... Housing 50 ... Slit-like opening 60 ... Partition part 70 ... Partition plate member 100 ... Ventilation Opening 105 ... inner wall 110 ... interior wall 120 ... exterior wall 130 ... bent ventilation path 150 ... sound absorbing material

Claims (10)

A resonator having a slit-shaped opening,
A noise reduction structure characterized by being arranged on a wall surface of an inner wall of an opening of a building. A resonator having a slit-shaped opening,
A noise reduction structure characterized by being arranged in a space between an interior wall and an exterior wall in an opening of a building. A resonator having a slit-shaped opening,
A noise reduction structure characterized by being arranged on an interior wall provided with an opening of a building. A resonator having a slit-shaped opening,
A noise reduction structure arranged on a wall surface of an inner wall of an opening of a bent building. The noise reduction structure according to any one of claims 1 to 4, wherein the resonators are arranged in pairs so that the slit-shaped openings are opposed to each other. The noise reduction structure according to claim 1, wherein the resonator is divided into a plurality of sections by a partition plate member. The noise reduction structure according to any one of claims 1 to 6, wherein the resonator includes a box-shaped outer shell member having an open surface on one side and an L-shaped member. The noise according to any one of claims 1 to 6, wherein the resonator includes a box-shaped outer shell member having an open surface on one side, an L-shaped member, and a partition plate member. Reduction structure. The noise reduction structure according to any one of claims 1 to 8, wherein the resonator includes an air layer. The noise reduction structure according to claim 1, wherein the resonator does not have an air layer.

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