JP2013047858A - Sound absorption structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sound absorption structure which is easy to assemble and has a high sound absorbing effect and weather resistance.SOLUTION: A second plate member 150 is provided so as to be opposite to a first plate member 160 having many openings 110, and a plurality of perforated plates 310 and 320 having many openings 315 are disposed between the first plate member 160 and the second plate member 150. The first plate member 160 and the perforated plates 310 and 320 are different in opening ratios of the openings 110 and 315. The first plate member 160, the perforated plate 310, the perforated plate 320, and the second plate member 150 are arranged in order from a sound source and are formed so that the opening ratio increases as the distance from the sound source increases.

Description

  The present invention relates to a sound absorbing structure that can reduce sound from a sound source in a railway, road, or other place where sound is generated.

  Conventionally, in order to prevent noise from neighboring houses or public facilities, soundproof walls or the like as sound absorbing structures have been used around railway facilities and highways. Also, in a room such as a conference room or a concert hall, a sound absorbing structure is used to prevent sound leakage to an adjacent room or unnecessary interference of sound.

  For example, Patent Document 1 discloses a frame structure of a soundproof panel and a soundproof panel having the frame structure. In the soundproof panel disclosed in Patent Document 1, even when a load from a vehicle collides with the soundproof panel in a traffic disaster, the frame structure of the soundproof panel is unlikely to cause the load to pass through the soundproof panel or to scatter members. The purpose is to provide.

  The structure of the soundproof panel described in Patent Document 1 is a rectangular soundproof panel in which a frame is formed using a frame material around a soundproof plate having sound insulation properties, and the bending strength of the facing frame material is substantially the same. It is. As a result, when the load dropped from the vehicle hits, the facing frame members are deformed to the same extent, so that the load can be prevented from passing through the soundproof panel. In addition, even when retaining using a retaining material, the load concentrates on the retaining material on the one side of the frame material, and it is possible to prevent breakage and scattering of the retaining material and damage to the soundproof plate. An effect is obtained.

  On the other hand, Patent Document 2 discloses a panel sound absorbing device. In the structure of the sound absorbing device described in Patent Document 2, a number of punchings are applied to the metal front plate and back plate, and a rough cloth such as a cold chill is laid on the back surface of the front plate. When using a single sound absorbing plate or two sound absorbing plates, one that is connected to a metal frame and filled with glass wool or rock wool in the inner hollow part surrounded by a gap is used. In this case, a vertically long air layer is formed between other panels and walls, and the end faces are closed and connected with a metal side frame without gaps. It is made to oppose, an air layer part is formed vertically between back plates, and an end surface is closed and connected with a metal side frame without a gap.

JP 2004-52380 A JP-A-62-0799018

  However, the soundproof panel described in Patent Document 1 is effective against a lack of strength at the time of a disaster, but the effect cannot be enhanced with respect to soundproofing that is necessary in normal times. Moreover, since a member is fixed inside the soundproof panel, manufacturing is difficult.

  On the other hand, in the sound absorbing device described in Patent Document 2, the inner hollow portion is filled with glass wool material or the like, and it is necessary to uniformly fill the glass wool material into the sound absorbing device. Is required. In addition, it is necessary to position in order to fix the sound absorbing plate at the time of manufacturing, which is difficult to manufacture.

  Moreover, in the soundproof panel described in Patent Document 1 and the sound absorbing device described in Patent Document 2, it is difficult to obtain a high sound attenuation effect in a wide frequency band. That is, actual noise depends on sound in a wide frequency band. Therefore, sound absorption using only glass wool described in Patent Document 2 cannot stably reduce sound in a wide frequency band with high weather resistance.

  An object of the present invention is to provide a sound absorbing structure that is easy to assemble, has a high sound absorbing effect, and has weather resistance.

  Another object of the present invention is to provide a sound absorbing structure having high weather resistance and capable of stably reducing sound in a wide frequency band.

Means for Solving the Problems and Effects of the Invention

(1)
The sound absorbing structure according to the present invention is a sound absorbing structure capable of absorbing sound from a sound source, and is provided with a first plate member having a large number of openings and a first plate member facing the first plate member. Two plate members and one or more perforated plates having a large number of openings and disposed between the first plate member and the second plate member, the first plate member and the perforated plate The aperture ratios of the openings are different, the first plate member, the perforated plate, and the second plate member are arranged in this order from the sound source, and the aperture ratio decreases as the distance from the sound source increases.

  In this case, since the first plate member and the perforated plate are arranged so that the aperture ratio of the opening portion decreases as the distance from the sound source increases, the sound in a wide frequency band from the sound source is effectively reduced step by step. Can be made.

(2)
The perforated plate arranged at the position farthest from the sound source is represented by y ≦ 0.0086x + 0.0076, where x is a value obtained by dividing the plate thickness by the hole diameter of the opening, and y is the opening ratio of the opening. It may be formed so as to satisfy the relationship.

  In this case, the aperture ratio y is set so that the value x obtained by dividing the plate thickness by the hole diameter and the aperture ratio y satisfy the relationship of y ≦ 0.0086x + 0.0076 in the perforated plate disposed at the position farthest from the sound source. Therefore, the sound absorption rate can be improved.

(3)
The sound attenuating member further includes a sound attenuating member between the first plate member and the perforated plate, between the perforated plate and the second plate member, and between the perforated plates when there are a plurality of perforated plates. It may be arranged in at least one of them.

  In this case, since the sound attenuating member is disposed at least at one position between each of the first plate member, the perforated plate, and the second plate member, it is compared with the case of only the first plate member, the perforated plate, and the second plate member. Thus, the sound of the sound source can be further effectively reduced.

(4)
The opening may comprise a small hole.

  In this case, since the opening is made of a small hole, the sound of the sound source can be effectively reduced.

(5)
The perforated plate is preferably made of an aluminum member.

  In this case, since the perforated plate is made of an aluminum member, the perforated plate can be manufactured at a low cost and can be easily processed to form a large number of minute holes. Moreover, recyclability improves by using an aluminum member.

(6)
The first plate member and the second plate member are preferably made of an aluminum member.

  In this case, since the first plate member and the second plate member are made of an aluminum member, the first plate member and the second plate member can be manufactured at low cost, and can be easily processed to form a large number of minute holes. Moreover, recyclability improves by using an aluminum member.

(7)
The opening is preferably formed by embossing.

  In this case, since the opening part in a perforated plate is formed by embossing, a micropore can be formed uniformly. Moreover, since the rigidity of the porous plate can be increased by the mountain shape and the valley shape at the time of embossing, even if a thin porous plate is used, the rigidity of the porous plate itself can be increased, and the sound absorbing structure Work efficiency in manufacturing can be increased.

(8)
The opening may be formed by punching.

  In this case, even if a thick plate material is used, a large number of openings can be formed by punching.

(9)
The perforated plate may have a damping structure.

  In this case, since the perforated plate itself has a damping structure, vibration due to resonance of the perforated plate can be reduced, and the relative speed difference between the perforated plate and air can be increased to prevent a decrease in sound absorption performance. As a result, the sound absorbing structure can effectively reduce the sound from the sound source.

(10)
At least two perforated plates may be arranged in contact.

  In this case, by arranging the two porous plates in contact with each other, the pair of porous plates themselves have vibration damping properties, so that vibration due to the resonance of the porous plates is reduced, and the relative speed difference between the porous plate and air is reduced. By increasing the size, it is possible to prevent a decrease in sound absorption performance. As a result, the sound absorbing structure can effectively reduce the sound from the sound source.

(11)
The perforated plate may be made of a plate material having damping properties.

  In this case, since the perforated plate itself has vibration damping properties, vibration due to the resonance of the perforated plate can be reduced, and the relative speed difference between the perforated plate and air can be increased to prevent a decrease in sound absorption performance. As a result, the sound absorbing structure can effectively reduce the sound from the sound source.

Schematic perspective view showing an example of a soundproof wall using a sound absorbing structure Schematic explanatory drawing showing an example of multiple units Typical sectional drawing which shows an example of the cross section of the state which accommodated the several unit in the box member Schematic perspective view enlarging a part of the sound barrier (A) is a schematic sectional view of a porous plate, (b) is a schematic plan view of the porous plate. (A) is a schematic sectional view of a porous plate, (b) is a schematic plan view of the porous plate. Schematic diagram for explaining the surface hole and the aperture ratio of the perforated plate Schematic diagram for explaining the aperture ratio of the perforated plate Schematic diagram for explaining a state in which a sound attenuating member is attached to a perforated plate Schematic diagram for explaining a state in which a sound attenuating member is attached to a perforated plate Schematic sectional view for explaining a soundproof wall including a sound attenuating member Schematic diagram for explaining an example of a soundproof wall Schematic diagram for explaining the effect of the soundproof wall in FIG. Typical sectional drawing which shows an example of the cross section of the sound-absorbing structure which concerns on this Embodiment (A) is a schematic sectional view of a porous plate, (b) is a schematic plan view of the porous plate. (A) is a schematic sectional view of a porous plate, (b) is a schematic plan view of the porous plate. Schematic sectional view for explaining a sound absorbing structure further including a sound attenuating member in the sound absorbing structure Schematic cross-sectional view for explaining a state where a sound attenuating member is attached to a perforated plate

  Hereinafter, reference examples and embodiments according to the present invention will be described. In the reference example, a case where the sound absorbing structure is applied to a soundproof wall structure will be described.

(Reference example)
FIG. 1 is a schematic perspective view showing an example of a soundproof wall using a sound absorbing structure.

  The soundproof wall 100 of FIG. 1 is composed of a box member 150 in which a space is formed. In the box member 150, a large number of small holes 110 are formed in the surface 160. Further, in the present reference example, many small holes 110 are formed by punching. These many small holes 110 have, for example, a hole diameter of 0.3 mm or more and 3 mm or less, and an opening ratio of the surface 160 of 10% or less. Further, the box member 150 is made of a steel plate (for example, a highly weather-resistant plated steel plate). Thereby, the manufacturing cost of the box member 150 can be kept low.

  In addition, as shown in FIG. 1, a plurality of units 200 are provided in the internal space of the box member 150. Details of the plurality of units 200 will be described later. In FIG. 2, for the sake of explanation, the upper part of the box member 150 is shown open, but in actual use, all six surfaces are surrounded. Further, the surface 160 may be screwed as a lid portion and may be formed so as to be removable. In this case, the screw is preferably made of the same member as the box member 150.

  In this reference example, the box member 150 is made of a steel plate, but is not limited to this, and may be made of any other metal processing member, resin, or the like. Furthermore, although the large number of small holes 110 in the surface 160 are formed by punching, the present invention is not limited to this, and may be formed by embossing or other arbitrary processing.

  Next, FIG. 2 is a schematic explanatory diagram illustrating an example of the plurality of units 200. FIG. 2 shows a state where one unit 200 is pulled out from the box member 150 and the internal structure of the unit 200 is separated.

  As shown in FIG. 2, the unit 200 is formed of a first frame member 210, a second frame member 220, a third frame member 230, a porous plate 310 and a porous plate 320.

  As shown in FIG. 2, the porous plate 310 is sandwiched between the first frame member 210 and the second frame member 220, and the porous plate 320 is sandwiched between the second frame member 220 and the third frame member 230. Further, the first frame member 210, the second frame member 220, and the third frame member 230 have substantially the same outer size as the region of the internal space of the box member 150.

  In the reference example, the case of the first frame member 210, the second frame member 220, and the third frame member 230 has been described. However, the present invention is not limited to this, and the unit 200 is composed of a plurality of other frame members and the like. It may be configured. The unit 200 preferably has a shape that occupies the internal space of the box member 150.

  Next, FIG. 3 is a schematic cross-sectional view showing an example of a cross section in a state where a plurality of units 200 are housed in a box member 150.

  As shown in FIG. 3, the outer peripheral portion of the porous plate 310 is sandwiched between the first frame member 210 and the second frame member 220, and the porous plate 320 is interposed between the second frame member 220 and the third frame member 230. The outer peripheral part of is held.

  Further, by sandwiching the porous plate 310 and the porous plate 320 in the first frame member 210, the second frame member 220, and the third frame member 230, the porous plate 310 and the porous plate 320 are placed in the internal space of the box member 150. It is formed so as not to contact the surface.

  Moreover, as shown in FIG. 3, the thickness of the 1st frame member 210 is L1, the thickness of the 2nd frame member 220 is L2, and the thickness of the 3rd frame member 230 is L3. These thicknesses L1, L2 and L3 are determined by the wavelength of the sound wave to be absorbed among the sound waves coming from the sound source, and the thickness, hole diameter and aperture ratio of the perforated plate. Therefore, in this reference example, the values of the thicknesses L1, L2 and L3 are different from each other. However, the present invention is not limited to this, and any two thicknesses may be the same value. L2 and L3 may be the same numerical value. Further, the perforated plate 310 and the perforated plate 320 are not limited to the case where they are arranged in parallel, but in a state where they are opposed at an arbitrary angle, such as when they are substantially parallel or arranged in parallel. There may be.

  Next, the first frame member 210, the second frame member 220, and the third frame member 230 are made of resin, and the box member 150 is made of a steel plate as described above. Furthermore, as will be described later, the porous plate 310 and the porous plate 320 are made of an aluminum plate. All members may be made of an aluminum member. Thereby, there is no possibility that a member will deteriorate by electric corrosion. For example, if the box member 150, the perforated plates 310 and 320, the screws, etc. are all made of an aluminum member except for the first frame member, the second frame member, and the third frame member, the occurrence of electrolytic corrosion is ensured. Can be prevented. The first frame member 210, the second frame member 220, and the third frame member 230 may be screwed at a portion that does not contact the perforated plates 310 and 320, or may be bonded to each other with an adhesive. Crimping by may be used.

  In this case, as shown in FIG. 3, the outer peripheral portions of the perforated plate 310 and the perforated plate 320 are supported by the first frame member 210, the second frame member 220, and the third frame member 230. As a result, the perforated plate 310 and the perforated plate 320 do not contact the box member 150. Therefore, it is possible to prevent the occurrence of an electrochemical reaction (hereinafter abbreviated as an electrolytic corrosion reaction) that occurs in the porous plates 310 and 320 and the box member 150 due to the influence of humidity or the like. That is, the electrolytic corrosion reaction occurs when different metals, in this embodiment, the steel plate and the aluminum plate correspond to different metals and contact each other in a state of having moisture (a state where there is an electrolyte). In this embodiment, since the soundproof wall 100 is usually installed outdoors, it tends to have moisture due to wind and rain. Therefore, when the steel plate and the aluminum plate are in contact with each other, the metal part disappears due to corrosion. As a result, the porous plates 310 and 320 may disappear, and the weather resistance is poor. However, in this reference example, the occurrence of an electrolytic corrosion reaction can be prevented, the disappearance of the porous plates 310 and 320 can be prevented, and the weather resistance can be improved.

  Next, FIG. 4 is a schematic perspective view in which a part of the soundproof wall 100 is enlarged.

  As shown in FIG. 4, a water drain hole 180 is formed in a part of the box member 150 of the soundproof wall 100. Thereby, even when the soundproof wall 100 is installed outdoors, rainwater or the like that has entered the box member 150 through the many small holes 110 of the surface 160 can be discharged.

  As described above, in the soundproof wall 100 in this reference example, the porous plate 310 and the porous plate 320 and the box member 150 are formed by the first frame member 210, the second frame member 220, and the third frame member 230 made of resin. Since it is configured so as not to come into contact with each other and the drainage hole 180 is formed, an electrolytic corrosion reaction can be prevented.

  Next, the porous plate 310 and the porous plate 320 will be described. FIG. 5A is a schematic cross-sectional view of the porous plate 310, and FIG. 5B is a schematic plan view of the porous plate 310.

  As shown in FIG. 5A, the perforated plate 310 is continuously formed with a mountain shape 311 and a valley shape 312 by embossing. When the embossed peak shape 311 and the valley shape 312 exceed the ductility of the aluminum plate of the porous plate 310, minute holes 315 are formed in the aluminum plate. Note that the minute hole 315 formed by embossing is not a circular hole but a shape close to a cruciform hole. Hereinafter, the shape close to the cross-shaped hole will be described as a circular hole having an equivalent hole area.

  Thus, by processing the aluminum plate by embossing, it becomes possible to form a uniform and minute porous 315.

  Moreover, as shown in FIG.5 (b), the rigidity of the perforated panel 310 can be improved by forming alternately the mountain shape 311 and the valley shape 312 in zigzag form. That is, even when the thickness of the porous plate 310 is thin, the rigidity can be increased by embossing, so that the assembly efficiency is improved and the soundproof wall 100 can be easily manufactured.

  In the porous plate 310 shown in FIG. 5, the pore diameter of the minute porous 315 is, for example, 0.05 mm or more and 0.15 mm or less, and the aperture ratio of the porous plate 310 is 0.3% or more and 1.0% or less.

  Next, FIG. 6A is a schematic cross-sectional view of the porous plate 320, and FIG. 6B is a schematic plan view of the porous plate 320.

  As shown to Fig.6 (a), the perforated plate 320 is continuously formed with the mountain shape 321 and the valley shape 322 by embossing. When the embossed mountain shape 321 and valley shape 322 exceed the ductility of the aluminum plate of the perforated plate 320, minute holes 325 are formed in the aluminum plate. Note that the minute hole 325 formed by embossing is not a circular hole but a shape close to a cruciform hole. Hereinafter, the shape close to the cross-shaped hole will be described as a circular hole having an equivalent hole area.

  Thus, by processing the aluminum plate by embossing, it becomes possible to form a uniform and minute porous 325.

  Moreover, as shown in FIG.6 (b), the rigidity of the perforated panel 320 can be improved by forming alternately the mountain shape 321 and the valley shape 322 in zigzag form. That is, even when the thickness of the porous plate 320 is thin, the rigidity can be increased by embossing, so that the assembly efficiency is improved and the soundproof wall 100 can be easily manufactured.

  In the porous plate 320 shown in FIG. 6, unlike the porous plate 310 shown in FIG. 5, the pore diameter of the minute porous 325 is, for example, 0.05 mm or more and 0.15 mm or less, and the aperture ratio of the porous plate 320 is Is 0.2% or more and 0.8% or less. That is, the aperture ratio is smaller than that of the porous surface 160 shown in FIG. 1, and the aperture ratio is lower than that of the porous plate 310 shown in FIG. That is, from the larger aperture ratio to the smaller aperture ratio, the number of small holes 110 on the surface 160, the minute holes 315, and the minute holes 325 are in this order. This effect will be described later.

  In the perforated plates 310 and 320 described above, each parameter is set so as to cause a viscous action on the air passing through the perforations 315 and 325. As a result, when a viscous damping action occurs in the air passing through the perforations 315 and 325, the air vibration is converted into thermal energy, and the air vibration is attenuated. As a result, the sound absorption effect can be exhibited in a relatively wide frequency band. It becomes like this.

  In this reference example, the holes 315 and 325 are formed by embossing, but the present invention is not limited to this, and may be formed by other arbitrary processing such as punching.

  FIG. 7 is a schematic diagram for explaining the aperture ratios of the small holes 110, the porous plate 310, and the porous plate 320 on the surface 160. The vertical axis in FIG. 7 indicates the normal incidence sound absorption coefficient for the sound from the sound source, and the horizontal axis indicates the 1/3 octave band frequency (Hz).

  In this reference example, since the sound source is noise and is a sound barrier that protects the noise, the noise used as the sound source shows a high value in a specific frequency range. Therefore, for example, in the case of railways, the main frequency band is from 400 Hz to 4 kHz, and in highways, etc., the main frequency band is from 250 Hz to 4 kHz. Therefore, noise can be efficiently absorbed by absorbing sound in that band. Can be reduced.

  A solid line A in FIG. 7 shows a calculated value of the normal incident sound absorption coefficient when the aperture ratio of the small hole 110 on the surface 160 is 5% and the aperture ratio of the porous plate 310 is 0.43%, and the broken line in FIG. B shows the calculated value of the normal incident sound absorption coefficient when the aperture ratio of the small holes 110 on the surface 160 is 0.43% and the aperture ratio of the porous plate 310 is 5%.

  Here, each parameter of the soundproof wall 100 indicated by a solid line A in FIG. 7 is that the thickness of the surface 160 is 0.8 mm, the opening ratio in the surface 160 is 5%, and the hole diameters of many small holes 110 are 0. 0.8 mm, the air layer (distance L1) is 15 mm, the hole diameter of the porous plate 315 of the porous plate 310 is 0.07 mm, the plate thickness of the porous plate 310 is 0.1 mm, and the aperture ratio in the porous plate 310 is 0.43%, the air layer (distance L2) is 30 mm, the pore diameter of the perforated plate 320 is 0.12 mm, the thickness of the perforated plate 320 is 0.1 mm, and the perforated plate 320 The aperture ratio is 0.36%, and the air layer (distance L3) is 53 mm.

  Since each of the surface 160 and the perforated plates 310 and 320 has a sound absorption peak frequency, the aperture ratio, the hole diameter, the plate thickness, and the air layer between the perforated plates are optimally designed, so that as shown by a solid line A in FIG. The sound absorption peak frequency can be set, and a high sound absorption rate can be obtained in a wide band, that is, the frequency band of the region AL.

  On the other hand, each parameter of the soundproof wall indicated by a dotted line B in FIG. 7 is that the thickness of the surface 160 is 0.8 mm, the aperture ratio in the surface 160 is 0.43%, and the hole diameters of the many small holes 110 are 0. 0.8 mm, the air layer (distance L1) is 15 mm, the hole diameter of the porous plate 315 of the porous plate 310 is 0.07 mm, the plate thickness of the porous plate 310 is 0.1 mm, and the aperture ratio in the porous plate 310 is Is 5%, the air layer (distance L2) is 30 mm, the hole diameter of the porous plate 325 of the porous plate 320 is 0.12 mm, the plate thickness of the porous plate 320 is 0.1 mm, and the opening in the porous plate 320 is The rate is 0.36%, and the air layer (distance L3) is 53 mm.

  That is, in the solid line A in FIG. 7, the one closer to the sound source in the order of the aperture ratio of the many small holes 110 is 5%, the aperture ratio of the porous 315 is 0.43%, and the aperture ratio of the porous 325 is 0.36%. While the value of the aperture ratio decreases in a stepwise manner toward the distance from the distance, in the broken line B in FIG. 7, the aperture ratio of the many small holes 110 is 0.43% and the aperture ratio of the porous 315 is 5%. The aperture ratio of the porous 325 increases or decreases stepwise with respect to the direction away from the sound source in the order of 0.36%.

  In this way, by comparing the solid line A and the broken line B in FIG. 7, the broken line B in FIG. 7 has an effect of having a normal incidence sound absorption coefficient of 0.6 or more only at a 1/3 octave band frequency of about 400 Hz to 800 Hz. On the other hand, in the solid line A in FIG. 7, the effect of a normal incident sound absorption coefficient of 0.6 or more is observed at a 1/3 octave band frequency at 500 Hz or more and 5 kHz or less. It was found that sound can be effectively absorbed even for road noise. If the aperture ratio increases or decreases in steps as described above, high sound absorption performance in a wide band cannot be obtained.

  From the above, it is possible to reduce the sound from the sound source step by step by setting it so that the aperture ratio decreases as the distance from the sound source increases, and as a result, it is possible to reduce the broadband sound. I found out that

(Other examples)
Furthermore, the porous plate 320 in the present reference example may be configured to satisfy the relationship of the following formula (1). Here, the porous plate 310 closer to the sound source is referred to as the first porous plate 310, and the porous plate 320 far from the sound source is referred to as the second porous plate 320. The second porous plate 320 farthest from the sound source is the lowermost porous plate 320.

  y ≦ 0.0086x + 0.0076 (1)

  In the above formula (1), x is a value obtained by dividing the plate thickness of the perforated plates 310 and 320 by the hole diameter of the perforated plates 315 and 325, y is the aperture ratio of the perforated plates 310 and 320, and the aperture of the perforated plate 320 When the rate y satisfies the equation (1), the sound absorption rate reference value of the road sound absorption panel of JH (former Japan Highway Public Corporation) is satisfied.

  Note that the sound absorption coefficient reference value of the road sound absorption panel in JH is 0.7 or more at 400 Hz and 0.8 or more at 1 kHz.

  Table 1 shows the result of measuring the value of the sound absorption coefficient for the sound from the sound source for each frequency by changing the aperture ratio of the porous plate 320 of the lowermost layer (second layer). Here, Case 1 is set within a range where the aperture ratio y of the second porous plate 320 satisfies the relationship of the expression (1), while Case 2 has an aperture ratio y of the second porous plate 320. It is set outside the range that satisfies the relationship of the expression (1). The aperture ratio y of the first porous plate 310 is set outside the range satisfying the relationship of the expression (1) for both Case1 and Case2.

  FIG. 8 is a graph of the sound absorption rate values in Table 1. The vertical axis of FIG. 8 indicates the sound absorption rate with respect to the sound from the sound source, and the horizontal axis indicates 1/3 octave band frequency (Hz).

  As shown in FIG. 8, in Case 1 where the aperture ratio y of the second porous plate 320 is set within a range satisfying the relationship of the expression (1), the aperture ratio y of the second porous plate 320 is ( 1) The sound absorption rate is higher than Case 2 set outside the range that satisfies the relationship of the expression (1). Specifically, the sound absorption coefficient of Case 1 at 400 Hz is higher than 0.7, which is the reference value of the sound absorption coefficient of JH at 400 Hz, while the sound absorption coefficient of Case 2 at 400 Hz is the reference value of the sound absorption coefficient of JH at 400 Hz. It is lower than 0.7. The sound absorption coefficient of Case 1 at 1 kHz is higher than 0.8, which is the reference value of the sound absorption coefficient of JH at 1 kHz, while the sound absorption coefficient of Case 2 at 1 kHz is a reference value of the sound absorption coefficient of JH at 1 kHz. Lower than 8.

  From the above, in the lowermost porous plate 320, the sound absorption rate is improved by setting the aperture ratio y so that the value x obtained by dividing the plate thickness by the hole diameter and the aperture ratio y satisfy the expression (1). I understood that.

  Note that the aperture ratio y of the first porous plate 310 may be set so as to satisfy the relationship of the expression (1).

(Still other examples)
Next, the soundproof wall 100a will be described with reference to the drawings. The soundproof wall 100 a is obtained by sticking a sound attenuating member to the perforated plates 310 and 320 of the soundproof wall 100. FIG. 9 and FIG. 10 are schematic diagrams for explaining a state in which a sound attenuating member is attached to the perforated plate 310 and the perforated plate 320.

  As shown in FIGS. 9 and 10, the sound attenuating member 318 and the sound attenuating member 328 are attached to the outer peripheral regions of the perforated plate 310 and the perforated plate 320, respectively. Thereby, the rigidity of the porous plate 310 and the porous plate 320 can be increased. Furthermore, since the perforated plates 310 and 320 are formed of a composite material together with the sound attenuating members 318 and 328, the resonance peak can be reduced.

  As a result, sound can be more effectively reduced in the porous plate 310 and the porous plate 320. In this example, the sound attenuating members 318 and 328 are attached to the perforated plate 310 and the perforated plate 320. However, the present invention is not limited to this, and the sound attenuating member 318 is provided on the entire surface of the perforated plate 310 and the perforated plate 320. , 328, and then embossing to form minute porous 315, 325, and sound attenuating members 318, 328 are attached only to one of the front and back surfaces of porous plate 310 and porous plate 320 You may let them. Further, as the sound attenuating members 318 and 328, any of various tape members, coating materials, coating materials, or arbitrary members may be used. Furthermore, in this reference example, one porous plate 310 and one porous plate 320 are used. However, the present invention is not limited to this, and a porous plate having a damping function may be used. A perforated plate in which perforated plates are laminated may be used. That is, a porous plate that is the same as or different from the porous plate may be contacted and used as one porous plate. By applying damping to the perforated plate by these means, vibration due to resonance of the perforated plate can be reduced, the relative speed difference between the perforated plate and air can be increased, and deterioration in sound absorption performance can be prevented.

(Still other examples)
FIG. 11 is a schematic cross-sectional view for explaining a soundproof wall 100b that further includes sound attenuating members 510, 520, and 530 in the soundproof wall 100. FIG.

  As shown in FIG. 11, in the soundproof wall 100 b, a sound attenuating member 510 is provided in a space formed by a large number of small holes 110, the first frame member 210, and the porous plate 310 on the surface 160 of the box member 150. A sound attenuating member 520 is provided in a space formed by the minute perforations 315, the second frame member 220 and the perforated plate 320 of the plate 310, and the minute perforations 325, the third frame member 230 and the box member 150 of the perforated plate 320 are provided. A sound attenuating member 530 is provided in the space to be formed.

  In the soundproof wall 100b in the other example described above, the sound attenuating members 510, 520, and 530 are provided in each space. However, the present invention is not limited to this, and at least one of the sound attenuating members 510, 520, 530 is provided. One sound attenuating member may be provided, and as the unit 200, the sound attenuating members 510, 520, and 530 are provided as at least one of the first frame member 210, the second frame member 220, and the third frame member 230, respectively. It may be fixed.

  In this case, the soundproof wall 100 b can be easily manufactured by inserting the unit 200 into the box member 150.

  The sound attenuating members 510, 520 and 530 may be made of PET fiber resin, glass wool, rock wool, open cell urethane, non-woven fabric, or any other member.

(Still other examples)
FIG. 12 is a schematic diagram for explaining an example of the soundproof wall 100c. 12A shows a schematic perspective view of the soundproof wall 100c, and FIG. 12B shows a schematic cross-sectional view of the soundproof wall 100c.

  As shown to Fig.12 (a), many holes 110c are formed in the surface 160c of the box member 150c of the sound-insulating wall 100c by the louver fin shape. In FIG. 12A, a large number of holes 110c are arranged in a plurality of rows. However, the present invention is not limited to this, and the holes 110c may be arranged in a staggered manner or any other method.

  12B, the unit 200 in the soundproof wall 100c includes a box member 150c, perforated plates 310, 320, and 330, a first frame member 210, a second frame member 220, a third frame member 230, and A fourth frame member 240 is provided.

  As in FIG. 3, the outer peripheral portion of the porous plate 310 is sandwiched between the first frame member 210 and the second frame member 220, and the porous plate 320 is interposed between the second frame member 220 and the third frame member 230. The outer peripheral portion of the porous plate 330 is sandwiched between the third frame member 220 and the fourth frame member 230. Further, a porous plate 335 is formed in the porous plate 330 as in the case of the porous plates 310 and 320 of FIGS. 5 and 6.

  12B, the thickness of the first frame member 210 is L1, the thickness of the second frame member 220 is L2, the thickness of the third frame member 230 is L3, and the fourth The thickness of the frame member 240 is L4. These thicknesses L1, L2, L3 and L4 are determined by the wavelength of the sound wave to be absorbed among the sound waves coming from the sound source, and the thickness, hole diameter and aperture ratio of the perforated plate. Therefore, in this reference example, the values of the thicknesses L1, L2, L3, and L4 are different from each other. However, the present invention is not limited to this, and any two thicknesses may be the same value. L1, L2, L3, and L4 may be the same numerical value. Further, the perforated plate 310 and the perforated plate 320 are not limited to the case where they are arranged in parallel, but in a state where they are opposed at an arbitrary angle, such as when they are substantially parallel or arranged in parallel. There may be.

  Since the large number of holes 110c are formed in a louver fin shape, it is possible to efficiently prevent rainwater from entering, and to capture sound from a sound source to be absorbed. As a result, the sound of the sound source can be reduced efficiently. Moreover, there is an effect as a protective plate for preventing intrusion when a load being transported falls or when stones or the like are scattered.

  FIG. 13 is a schematic diagram for explaining the effect of the soundproof wall 100c in FIG. The vertical axis in FIG. 13 represents the normal incident sound absorption coefficient for the sound from the sound source, and the horizontal axis represents the 1/3 octave band frequency (Hz).

  Here, each parameter of the soundproof wall 100c shown in FIG. 12 is that the thickness of the surface 160c is 1 mm, the aperture ratio in the surface 160c is 22.8%, the air layer (distance L1) is 10 mm, The hole diameter of the plate 310 is 0.1 mm, the plate thickness of the porous plate 310 is 0.1 mm, the aperture ratio in the porous plate 310 is 0.89%, the air layer (distance L2) is 5 mm, The hole diameter of the porous 325 of the plate 320 is 0.07 mm, the plate thickness of the porous plate 320 is 0.1 mm, the aperture ratio in the porous plate 320 is 0.55%, and the air layer (distance L3) is 30 mm. Yes, the pore diameter of the porous plate 335 of the porous plate 330 is 0.07 mm, the plate thickness of the porous plate 330 is 0.1 mm, the aperture ratio in the porous plate 330 is 0.24%, and the air layer (distance L4) Is 45 mm. (Note that the thickness of the surface 160c including the processing height of the louver fins is 12 mm.)

  As described above, since the surface 160c and the perforated plates 310, 320, and 330 each have a sound absorption peak frequency, the aperture ratio, the hole diameter, the plate thickness, and the air layer between the perforated plates are optimally designed, as shown in FIG. The four sound absorption peak frequencies can be set to the above, and by designing them so as to be continuously arranged, a high sound absorption coefficient can be obtained in a wide frequency band.

  In FIG. 12, a large number of holes 110c having a louver fin shape are formed on the surface 160c. However, the present invention is not limited to this, and a large number of holes are formed in the porous plate 310, the porous plate 320, and the porous plate 330 by a louver fin shape. May be formed. Moreover, it is not limited to a louver fin shape, It is good also as forming other arbitrary hole shapes, such as a slit shape, circular shape, an elliptical shape, and an unusually shaped hole.

  From the above, the unit 200 is formed by sandwiching the plurality of perforated plates 310, 320 with the plurality of frame members 210, 220, 230 with respect to the box member 150 constituting the soundproof walls 100, 100 a, 100 b, 100 c. Thus, the unit 200 can be easily put into the internal space of the box member 150 in the manufacturing process. As a result, the soundproof wall 100 can be easily manufactured, and positioning work for fixing the plurality of perforated plates 310 and 320 to the internal space of the box member 150 can be reduced. Further, by being unitized, each internal space inside the unit 200 is kept airtight except for the perforated plates 315 and 325 of the perforated plates 310 and 320, so that the sound from the sound source can be effectively reduced. In this case, the sound from the sound source is absorbed by the large number of small holes 110 in the box member 150, and the sound is absorbed by the plurality of perforated plates 310, 320 sandwiched between the plurality of frame members 210, 220, 230. The

  Further, the two porous plates 310 and 320 are sandwiched by the three frame members 210, 220, and 230 to form a unit, and the unit 200 can be easily accommodated in the box member 150. In addition, since the three frame members are made of a resin that is a non-conductor, and the plurality of perforated plates 310 and 320 do not contact the inner peripheral surface of the box member 150, the perforated plates 310 and 320 are prevented from being damaged during manufacturing. And the electrolytic corrosion of the perforated plates 310 and 320 can be prevented. And the durability and weather resistance of the soundproof wall 100 can be improved. As a result, the sound absorption performance can be maintained for a long time.

  Further, since the plurality of perforated plates 310 and 320 are made of an aluminum member, and the perforated plates 315 and 325 in the perforated plates 310 and 320 are formed by embossing, a mountain shape 311, a valley shape 312, and a mountain shape 321 at the time of embossing. Since the rigidity of the porous plates 310 and 320 can be increased by the valley shape 322, the rigidity of the porous plates 310 and 320 themselves can be increased even when the thin porous plates 310 and 320 are used. As a result, the work efficiency in manufacturing the soundproof wall 100 can be increased. Furthermore, since an aluminum member is used, it can be manufactured at a low cost, and a large number of fine pores 315 and 325 that are easy to process can be formed, thereby improving recyclability. Therefore, all the members of the soundproof wall 100 may be made of an aluminum member.

  Further, since the surface 160 and the perforated plates 310 and 320 are arranged so that the aperture ratio decreases as the distance from the sound source increases, it is possible to effectively reduce the sound in a wide frequency band. Further, since the water draining hole 180 is formed, rainwater can be drained from the water draining hole 180 even when the water is infiltrated by rainwater or the like into the internal space of the box member 150 when installed outdoors. It can be discharged and electric corrosion can be prevented.

  Furthermore, in the lowermost porous plate 320, since the aperture ratio y is set so that the value x obtained by dividing the plate thickness by the hole diameter and the aperture ratio y satisfy the relationship of the expression (1), the sound absorption coefficient is improved. be able to.

  Furthermore, sound attenuating members 318, 328, 510, 520, 530 are arranged in at least one of the plurality of spaces separated by the plurality of frame members 210, 220, 230 and the plurality of perforated plates 310, 320, Since it is unitized, the soundproof wall 100 can be easily manufactured, and the sound of the sound source can be further effectively reduced as compared with the case of only the plurality of perforated plates 310 and 320.

  Further, since the sound attenuating members 510, 520, 530 are made of a porous material, non-woven fabric, glass wool, or PET fiber material, the sound attenuating members 510, 520, 530 are compared with the case where the glass wool or PET fiber material is simply disposed inside the box member 150. Thus, the bias of the sound attenuating members 510, 520, and 530 due to its own weight can be eliminated. As a result, sound from the sound source can be effectively reduced in the soundproof wall 100.

  In addition, the unit 200 is formed by sandwiching the plurality of perforated plates 310, 320, and 330 by the plurality of frame members 210, 220, 230, and 240 with respect to the box member 150c that constitutes the soundproof wall 100c. The unit 200 can be easily inserted into the internal space of the box member 150c. As a result, the soundproof wall 100c can be easily manufactured, and the positioning work for fixing the plurality of perforated plates 310, 320, 330 to the internal space of the box member 150c can be reduced. Further, by being unitized, each internal space inside the unit 200 is kept airtight except for the perforated plates 315, 325, and 335 of the perforated plates 310, 320, and 330, so that the sound from the sound source is effectively reduced. be able to. Further, in this case, while rainwater is shielded, sound from the sound source is transmitted through the small holes 110 having a louver fin shape in the box member 150c while being absorbed, and is sandwiched between the plurality of frame members 210, 220, 230, and 240. Sound is absorbed by the plurality of perforated plates 310, 320, and 330.

  Further, since the four frame members are made of a resin that is a non-conductor, and the plurality of perforated plates 310, 320, 330 do not contact the inner peripheral surface of the box member 150c, the perforated plates 310, 320, 330 at the time of manufacture Damage can be prevented and electrolytic corrosion of the perforated plates 310, 320, and 330 can be prevented. And the durability and weather resistance of the soundproof wall 100c can be improved. As a result, the sound absorption performance can be maintained for a long time.

  Further, since the plurality of perforated plates 310, 320, and 330 are made of an aluminum member, and the perforated plates 310, 320, and 330 in the perforated plates 310, 320, and 330 are formed by embossing, a mountain shape and a valley shape at the time of embossing are formed. Thus, the rigidity of the perforated plates 310, 320, and 330 can be increased. Therefore, even when the thin perforated plates 310, 320, and 330 are used, the rigidity of the perforated plates 310, 320, and 330 themselves can be increased. As a result, work efficiency in manufacturing the soundproof wall 100c can be increased. Furthermore, since an aluminum member is used, it can be manufactured at a low cost, and a large number of fine pores 315, 325, and 335 that are easy to process can be formed, and the recyclability is improved. Therefore, all the members of the soundproof wall 100c may be made of an aluminum member.

  Further, since the surface 160c and the perforated plates 310, 320, and 330 are arranged so that the aperture ratio decreases as the distance from the sound source increases, it is possible to effectively reduce the sound in a wider frequency band.

  Furthermore, in the lowermost porous plate 330, since the aperture ratio y is set so that the value x obtained by dividing the plate thickness by the hole diameter and the aperture ratio y satisfy the relationship of the formula (1), the sound absorption coefficient is improved. be able to.

  Furthermore, the sound attenuating members 318, 328, 510, 520, 530 in at least one of the plurality of spaces separated by the plurality of frame members 210, 220, 230, 240 and the plurality of perforated plates 310, 320, 330. Further, another sound attenuating member is also arranged in the air layer (distance L4) in the same manner, and the sound of the sound source is further effectively reduced as compared with the case where only a plurality of perforated plates 310, 320, 330 are provided. Also good.

(This embodiment)
Next, an embodiment according to the present invention will be described.
FIG. 14 is a schematic cross-sectional view showing an example of a cross section of the sound absorbing structure according to the present embodiment.

  The sound absorbing structure 100d of FIG. 14 includes a first plate member 160, perforated plates 310 and 320, and a second plate member 150. The first plate member 160 is disposed to face the sound source, and the perforated plates 310 and 320 and the second plate member 150 are sequentially disposed so as to be parallel to the first plate member 160. Yes. In the present embodiment, the perforated plates 310 and 320 and the second plate member 150 are illustrated as being provided in parallel to the first plate member 160. However, the present invention is not limited to this, and parallel or arbitrary It may be arranged at intervals and angles.

  In the sound absorbing structure 100d shown in FIG. 14, air layers are formed between the first plate member 160 and the porous plate 310, between the porous plate 310 and the porous plate 320, and between the porous plate 320 and the second plate member 150, respectively. The

  The opening part 110 is provided in the 1st board member 160, The hole diameter of the opening part 110 is 0.3 mm or more and 3 mm or less, for example, and the aperture ratio of the 1st board member 160 is 10% or less. In the present embodiment, the first plate member 160 and the second plate member 150 are made of steel plates (for example, highly weather-resistant plated steel plates). Thereby, the manufacturing cost of the box member 150 can be kept low.

  Moreover, the aperture 315 is provided in the porous plate 310, and the hole diameter of the aperture 315 is, for example, 0.05 mm or more and 0.15 mm or less, and the aperture ratio of the porous plate 310 is 0.3% or more and 1 0.0% or less.

  Moreover, the aperture 325 is provided in the porous plate 320, and the hole diameter of the aperture 325 is, for example, 0.05 mm or more and 0.15 mm or less, and the aperture ratio of the porous plate 320 is 0.2% or more and 0. .8% or less.

  Each of the above parameters is set so as to cause a viscous action on the air passing through the openings 110, 315, and 325. As a result, when a viscous damping action occurs in the air passing through the openings 110, 315, and 325, the air vibration is converted into thermal energy, resulting in the damping of the air vibration. As a result, the sound absorption effect is obtained in a relatively wide frequency band. Can be demonstrated.

  Of the first plate member 160, the perforated plates 310 and 320, and the second plate member 150, the aperture ratio of the first plate member 160 is the largest, and the aperture ratio decreases in the order of the perforated plates 310 and 320. As a result, since the frequency band in which the first plate member 160 and the perforated plates 310 and 320 exhibit the sound absorption effect is different, the sound absorbing structure 100d using them has frequency components other than the resonance frequency over a wide frequency band. The sound absorption effect can be exerted on noise.

  The first plate member 160 and the perforated plates 310 and 320 can exhibit a high sound absorption effect over a wide frequency band by suppressing a sudden drop in the sound absorption coefficient. Further, by decreasing the aperture ratio stepwise in the order of the first plate member 160 and the perforated plates 310 and 320, the sound is porous with respect to sound having a wavelength shorter than the frequency of sound absorption at the opening 110 of the first plate member 160. Sound can be absorbed by the plates 310 and 320, and sound with a wavelength shorter than the frequency of sound absorption at the opening 315 of the porous plate 310 can be absorbed by the porous plate 320.

  Further, as shown in FIG. 14, the distance between the first plate member 160 and the porous plate 310 is a distance L1, and the distance between the porous plate 310 and the porous plate 320 is a distance L2, and the porous plate 320 and the second plate. The distance from the member 150 is a distance L3. As described above, the distances L1, L2, and L3 are different distances. However, the distances are not limited to this, and all may be the same distance.

  In the present embodiment, the first plate member 160, the perforated plates 310 and 320, and the second plate member 150 have a rectangular flat plate shape. However, the present invention is not limited to this. It is good also as what consists of a plane of a shape, an ellipse shape, and a triangular shape. Furthermore, the first plate member 160, the perforated plates 310 and 320, and the second plate member 150 of the sound absorbing structure 100d have an area of a predetermined size, but the present invention is not limited to this and solves manufacturing problems. Therefore, a sound absorbing structure having an area of a predetermined size may be formed by forming the sound absorbing structure 100d smaller than a predetermined size and providing a plurality of the sound absorbing structures 100d.

  Furthermore, the first plate member 160, the perforated plates 310 and 320, and the second plate member 150 are made of flat plates. However, the present invention is not limited to this, and one member is made of a flat plate and the other member is made of a thin film. May be. Moreover, all the members may consist of thin films. For example, all of the first plate member 160, the perforated plates 310 and 320, and the second plate member 150 may be made of an arbitrary plate material such as a steel plate (for example, a highly weather-resistant plated steel plate), an aluminum plate material, or a resin.

  Next, an example of the porous plate 310 and the porous plate 320 will be described. FIG. 15A is a schematic cross-sectional view of the porous plate 310, and FIG. 15B is a schematic plan view of the porous plate 310.

  As shown in FIG. 15A, the perforated plate 310 is formed with a mountain shape 311 and a valley shape 312 continuously by embossing. When the embossed mountain shape 311 and valley shape 312 exceed the ductility of the aluminum plate of the porous plate 310, minute openings 315 are formed in the aluminum plate. Note that the minute opening 315 formed by embossing is not a circular hole but a shape close to a cruciform hole. Hereinafter, the shape close to the cross-shaped hole will be described as a circular hole having an equivalent hole area.

  In this way, by processing the aluminum plate by embossing, it is possible to form a uniform and minute opening 315.

  Moreover, as shown in FIG.15 (b), the rigidity of the perforated panel 310 can be improved by forming alternately the mountain shape 311 and the valley shape 312 in zigzag form. That is, even when the thickness of the porous plate 310 is thin, the rigidity can be increased by embossing, so that the assembly efficiency is improved.

  Next, FIG. 16A is a schematic cross-sectional view of the porous plate 320, and FIG. 16B is a schematic plan view of the porous plate 320.

  As shown to Fig.16 (a), the perforated plate 320 is continuously formed with the mountain shape 321 and the valley shape 322 by embossing. When the embossed mountain shape 321 and valley shape 322 exceed the ductility of the aluminum plate of the porous plate 320, a minute opening 325 is formed in the aluminum plate. Note that the minute opening 325 formed by embossing is not a circular hole but a shape close to a cruciform hole. Hereinafter, the shape close to the cross-shaped hole will be described as a circular hole having an equivalent hole area.

  Thus, by processing the aluminum plate by embossing, a uniform and minute opening 325 can be formed.

  Moreover, as shown in FIG.16 (b), the rigidity of the perforated panel 320 can be improved by forming alternately the mountain shape 321 and the valley shape 322 in zigzag form. That is, even when the thickness of the porous plate 320 is thin, the rigidity can be increased by embossing, so that the assembly efficiency is improved and the soundproof wall 100 can be easily manufactured.

  In the porous plate 310 shown in FIG. 15, for example, the hole diameter of the opening 315 is 0.05 mm or more and 0.15 mm or less, and the opening ratio of the porous plate 310 is 0.3% or more and 1.0% or less. In the porous plate 320 shown in FIG. 16, for example, the hole diameter of the opening 325 is 0.05 mm or more and 0.15 mm or less, and the opening ratio of the porous plate 320 is 0.2% or more and 0.8% or less.

  In FIGS. 15 and 16, the perforated plates 310 and 320 are made of an aluminum member. However, the present invention is not limited to this, and the plate may be made of any other metal processing member or resin. Further, the openings 315 and 325 formed in the perforated plates 310 and 320 are formed by embossing. However, the present invention is not limited to this, and the openings 315 and 325 may be formed by punching or other arbitrary processing. .

  Further, in the lowermost porous plate 320, the aperture ratio y is set so that the value x obtained by dividing the plate thickness by the hole diameter and the aperture ratio y satisfy the relationship of the above-described formula (1). Thereby, a sound absorption rate can be improved. In addition, the aperture ratio y of the first porous plate 310 may be set so as to satisfy the relationship of the above-described formula (1).

  Next, FIG. 17 is a schematic cross-sectional view for explaining a sound absorbing structure 100e that further includes sound attenuating members 510, 520, and 530 in addition to the sound absorbing structure 100d.

  As shown in FIG. 17, in the sound absorbing structure 100 e, a sound attenuating member 510 is provided in the air layer formed by the first plate member 160 and the porous plate 310, and the air formed by the porous plate 310 and the porous plate 320. The sound attenuating member 520 is provided in the layer, and the sound attenuating member 530 is provided in the air layer formed by the perforated plate 320 and the second plate member 150.

  In the sound absorbing structure 100e, the sound attenuating members 510, 520 and 530 are provided in each air layer. However, the present invention is not limited to this, and at least one of the sound attenuating members 510, 520 and 530 is provided. A sound attenuating member may be provided, and the sound attenuating members 510, 520, and 530 may be fixed to the first plate member 160, the perforated plates 310, 320, and the second plate member 150, respectively.

  Thereby, the sound absorbing effect in the sound attenuating members 510, 520, and 530 is further added to the sound absorbing effect of the sound absorbing structure 100d including only the first plate member 160, the perforated plates 310 and 320, and the second plate member 150. Therefore, a more preferable sound absorbing effect can be realized.

  The sound attenuating members 510, 520 and 530 may be made of PET fiber resin, glass wool, rock wool, open cell urethane, non-woven fabric, or any other member.

  Next, the sound absorbing structure 100f will be described with reference to FIG. FIG. 18 is a schematic cross-sectional view for explaining a state in which a sound attenuating member is attached to the porous plate 310 and the porous plate 320. The sound absorbing structure 100f is obtained by attaching a sound attenuating member to the perforated plates 310 and 320 of the sound absorbing structure 100d.

  As shown in FIG. 18, a sound attenuating member 318 and a sound attenuating member 328 are attached to the entire surface of the perforated plate 310 and the perforated plate 320, respectively. Thereby, the rigidity of the porous plate 310 and the porous plate 320 can be increased. Furthermore, since the perforated plates 310 and 320 are formed of a composite material together with the sound attenuating members 318 and 328, the resonance peak can be reduced.

  As a result, sound can be more effectively reduced in the porous plate 310 and the porous plate 320. In this example, the sound attenuating members 318 and 328 are attached to the entire surface of the perforated plate 310 and the perforated plate 320, but the present invention is not limited to this. The attenuating members 318 and 328 may be attached, and the sound attenuating members 318 and 328 may be attached to only one of the front and back surfaces of the porous plate 310 and the porous plate 320. Further, as the sound attenuating members 318 and 328, any of various tape members, coating materials, coating materials, or arbitrary members may be used. Furthermore, in the present embodiment, the single porous plate 310 and the single porous plate 320 are used. However, the present invention is not limited to this, and a porous plate having an attenuation function may be used, and a plurality of porous plates may be used. Alternatively, a porous plate formed by stacking multiple porous plates may be used. That is, a porous plate that is the same as or different from the porous plate may be contacted and used as one porous plate. By applying damping to the perforated plate by these means, vibration due to resonance of the perforated plate can be reduced, the relative speed difference between the perforated plate and air can be increased, and deterioration in sound absorption performance can be prevented.

  As described above, in the sound absorbing structures 100d, 100e, and 100f, the first plate member 160 and the perforated plates 310 and 320 are disposed so that the aperture ratio of the opening portion decreases as the distance from the sound source increases. A wide frequency band sound from the sound source can be reduced stepwise and effectively.

  Further, in the lowermost porous plate 320, since the aperture ratio y is set so that the value x obtained by dividing the plate thickness by the hole diameter and the aperture ratio y satisfy the relationship of the above-described formula (1), the sound absorption coefficient is set. Can be improved.

  In addition, since the sound attenuating members 510, 520, and 530 are disposed at least at one location among the first plate member 160, the perforated plates 310 and 320, and the second plate member 150, the first plate member 160, the perforated plate, and the like. The sound of the sound source can be further effectively reduced as compared with the case of only 310, 320 and the second plate member 150. Moreover, since the sound attenuating members 510, 520, and 530 are made of a porous material, non-woven fabric, glass wool, or PET (Poly Ethylene Terephthalate) fiber material, the sound of the sound source can be further effectively reduced.

  Further, the openings 110, 315, and 325 may be any of small holes, circular holes, slit-shaped holes, irregular-shaped holes, and louver fin-shaped holes, so that the manufacturing cost can be reduced. Become.

  In addition, since each of the first plate member 160, the perforated plates 310 and 320, and the second plate member 150 is made of an aluminum member, it can be manufactured at a low cost and can be easily processed to form a large number of minute holes. it can. Moreover, recyclability improves by using an aluminum member.

  Further, since the openings 315 and 325 are formed by embossing, the openings can be formed uniformly. Moreover, since the rigidity of the porous plate can be increased by the mountain shape and the valley shape at the time of embossing, the rigidity of the porous plate 310, 320 itself can be increased even when the thin porous plate 310, 320 is used. And can absorb sound efficiently.

  Further, when the perforated plates 310 and 320 themselves have a damping structure, the vibration due to resonance of the perforated plates 310 and 320 is reduced, and the relative speed difference between the perforated plates 310 and 320 and air is increased, so that sound absorption performance is achieved. A decrease can be prevented. As a result, the sound absorbing structure can effectively reduce the sound from the sound source.

  The perforated plates 310 and 320 may be arranged in contact with each other or may be made of a plate member having vibration damping properties. In this case, since the perforated plate itself has vibration damping properties, vibration due to the resonance of the perforated plate can be reduced, and the relative speed difference between the perforated plate and air can be increased to prevent a decrease in sound absorption performance. As a result, the sound absorbing structure can effectively reduce the sound from the sound source.

  In the above reference example, the soundproof walls 100, 100a, 100b, and 100c correspond to sound absorbing structures, the surface 160 corresponds to a porous surface, the box member 150 corresponds to a box member, and the porous plates 310, 320, and 330 It corresponds to a plurality of perforated plates, the first frame member 210, the second frame member 220, the third frame member 230, and the fourth frame member 240 correspond to a plurality of support frames, the unit 200 corresponds to unitization, The shape 311 and the valley shape 312, the mountain shape 321 and the valley shape 322 correspond to shapes by embossing, the sound attenuating member 318, the sound attenuating member 328, the sound attenuating members 510, 520, and 530 correspond to the sound attenuating members, The draining hole 180 corresponds to a water draining hole.

  In the present embodiment, the sound absorbing structures 100d, 100e, and 100f correspond to the sound absorbing structure, the first plate member 160 corresponds to the first plate member, and the second plate member 150 corresponds to the second plate member. The perforated plates 310 and 320 correspond to a plurality of perforated plates, the openings 110, 315 and 325 correspond to the openings, and the mountain shape 311 and the valley shape 312, the mountain shape 321 and the valley shape 322 are embossed. The sound attenuating member 318, the sound attenuating member 328, and the sound attenuating members 510, 520, and 530 correspond to the sound attenuating members.

  Although the present invention has been described in the above preferred embodiment, the present invention is not limited thereto. It will be understood that various other embodiments may be made without departing from the spirit and scope of the invention. Furthermore, in this embodiment, although the effect | action and effect by the structure of this invention are described, these effect | actions and effects are examples and do not limit this invention. Furthermore, in this Embodiment, although the sound-insulating wall is illustrated as a sound-absorbing structure, it is not limited to this, It can apply to other arbitrary sound-absorbing structures.

DESCRIPTION OF SYMBOLS 100 Soundproof wall, sound absorption structure 150 Box member, 2nd board member 160 surface, 1st board member 180 Hole for draining 210 1st frame member 220 2nd frame member 230 3rd frame member 240 4th frame member 200 Unit 310,320,330 Perforated plate 311,321 Mountain shape 312,322 Valley shape 318,328 Sound attenuating member 510,520,530 Sound attenuating member

Claims (11)

A sound absorbing structure capable of absorbing sound from a sound source,
A first plate member having a number of openings;
A second plate member provided to face the first plate member;
Including one or more perforated plates provided with a large number of openings and disposed between the first plate member and the second plate member,
The aperture ratio of the opening is different between the first plate member and the porous plate, and the first plate member, the porous plate, and the second plate member are arranged in this order from the sound source, and away from the sound source A sound-absorbing structure formed so that the aperture ratio decreases with the increase in the number.   The perforated plate disposed at a position farthest from the sound source is expressed as y ≦ when the value obtained by dividing the plate thickness by the hole diameter of the opening is x and the opening ratio of the opening is y. The sound absorbing structure according to claim 1, wherein the sound absorbing structure is formed so as to satisfy a relationship of 0.0086x + 0.0076. A sound attenuating member;
The sound attenuating member is between the first plate member and the perforated plate, between the perforated plate and the second plate member, and between the perforated plates when there are a plurality of perforated plates. The sound-absorbing structure according to claim 1 or 2, wherein the sound-absorbing structure is disposed in at least one of them.   The sound absorbing structure according to any one of claims 1 to 3, wherein the opening is a small hole.   The sound absorbing structure according to any one of claims 1 to 4, wherein the perforated plate is made of an aluminum member.   The sound absorbing structure according to any one of claims 1 to 5, wherein the first plate member and the second plate member are made of an aluminum member.   The sound absorbing structure according to any one of claims 1 to 6, wherein the opening is formed by embossing.   The sound absorbing structure according to any one of claims 1 to 6, wherein the opening is formed by punching. The perforated plate is
The sound absorbing structure according to any one of claims 1 to 8, wherein the sound absorbing structure has a damping structure.   The sound absorbing structure according to any one of claims 1 to 9, wherein at least two of the perforated plates are arranged in contact with each other. The perforated plate is
The sound absorbing structure according to any one of claims 1 to 10, wherein the sound absorbing structure is made of a plate material having vibration damping properties.

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