JP2009037068A - Sound absorption structure and sound absorption apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound absorption structure which is small in the resistance of a stream, is excellent in sound absorption performance of a wide range of frequencies, is hardly deteriorated, is light in weight, and is installed in the stream. <P>SOLUTION: Metal fiber sheet materials are attached to both faces and at least one side face of a core material of a corrugated shape. The metal fiber sheet materials come into close contact with both surfaces of the core material and the cross sectional shapes of the metal fiber sheet materials are semi-circular or semi-arcuate shapes or are tapered on one side or are tapered on both sides in the sectional shapes of the metal fiber sheet materials on the side faces of the core material in which the metal fiber sheet materials exist; in addition, the sound absorption is installed with the side face side having the sectional shape toward upstream side of the stream. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sound absorbing structure and a sound absorbing device, and more specifically, a low pressure loss type sound absorbing structure suitable for measures against noise generated from a place where air flows, such as a factory exhaust duct and a machine exhaust duct. The present invention relates to a sound absorbing device.

There are many examples of noise coming from places with airflow, such as factory exhaust ducts and machine exhaust ducts, and noise countermeasures may be required.
The types of silencers used where there is a flow are roughly classified into A) sound absorption type, B) reactive type, and C) active type.
A is known in which a sound-absorbing material such as glass wool or rock wool is attached to the inner surface of the duct, or is distributed so as to partition the cross section of the duct with the sound-absorbing material.
As for B, there are known an expansion chamber shape in which the middle of the duct is thick, an interference shape in which sound is canceled out by a phase difference, a resonance shape such as Helmholtz and a side branch, and the like.
C analyzes the sound picked up by the microphone, artificially outputs the sound in the opposite phase and cancels it out.

However, such a silencer has the following problems.
A) Since rock wool and glass wool need a sufficient thickness to absorb sound, the duct becomes narrow. In particular, since the pressure loss of the duct is greatly increased if the air is arranged in a distributed manner, the output of the blower must be increased in order to ensure a predetermined exhaust performance. In addition, depending on the exhaust gas, the fiber binder significantly deteriorates, and the sound absorption performance decreases. Further, the fibers are scattered by the exhaust air.
B) Since a certain amount of space is required, it is difficult to install.
C) Expensive.

Further, in Patent Document 1, in a sound absorbing device that performs sound absorption by a back air layer, sound absorption from both sides is performed to a low frequency range by using a fluid property of a sound wave, with a limited thickness. A sound absorbing device is described. In this sound absorbing device (sound absorbing panel), an aluminum plate 102 is sandwiched between a pair of plate-like sound absorbing materials 101 and 103 formed by compression molding a metal fiber material. In this sound absorbing structure, a corrugated plate is sandwiched between metal fiber sheets. Thus, the structure can absorb sound from both sides, and is suitable for an acoustic partition and a sound absorbing plate for noise incident from both sides.
However, if the sound absorbing panel described in Patent Document 1 is placed parallel to the flow so as to be used for measures against noise generated from a place where there is an air flow such as an exhaust duct of a factory or an exhaust duct of a machine, Although the effect may be exerted, the side portion becomes a great resistance to the flow. Therefore, the exhaust function is impaired.
JP 2001-166780 A

  The present invention eliminates the problems of the conventional sound absorbing structure as described above, has low flow resistance, excellent sound absorption performance over a wide range of frequencies, is hardly deteriorated, and is installed in a lightweight flow. An object is to provide a sound absorbing structure.

The present invention
(1) The metal fiber sheet material is attached to both surfaces and at least one side surface of the corrugated core material, the metal fiber sheet material is in close contact with both surfaces of the core material, and the metal fiber sheet material is present. On the side surface side of the core material, the cross-sectional shape of the metal fiber sheet material is semicircular, semi-elliptical, one-side tapered or both-side tapered, and the side surface having the cross-sectional shape is installed toward the upstream side of the flow A sound-absorbing structure characterized by being used;
(2) The sound absorbing structure according to (1), wherein the corrugated peak height of the core material is gradually changed, whereby the width is gradually changed.
(3) The core material has a shape composed of a trunk and a branch, and the metal fiber sheet material is attached in close contact with at least one tip and a branch tip of the trunk of the core material. The cross-sectional shape of the metal fiber sheet material is a semicircle, a semi-ellipse, a one-side taper, or a both-side taper at the tip side of the branch that surrounds the core material and the metal fiber sheet material is in close contact, and has the cross-sectional shape. A sound absorbing structure characterized in that the tip side is installed and used toward the upstream side of the flow;
(4) The sound absorbing structure according to item (3), wherein the width of the branch portion of the core material is gradually changed, whereby the width is gradually changed.
(5) The sound absorption according to (3), wherein the core material has a corrugated shape, so that there are a plurality of distances between the metal fiber sheet material and the core material trunk. Structure,
(6) The material of the metal fiber sheet material is aluminum or an aluminum alloy, and after molding them into a sheet shape, a sintered and integrated material is used. (1) to (5) The sound absorbing structure according to any one of the above items and the sound absorbing structure according to any one of (7) (1) to (6), the plane on which the metal fiber sheet material is present is substantially parallel to the flow direction. Sound absorbing device, wherein the sound absorbing device is arranged in an opening having a flow at an interval,
Is to provide.
In the present invention, the flow means a flow of gas such as air or various exhaust gases, but may include a small amount of liquid such as mist or a solid such as fine particles.

  According to the sound absorbing structure of the present invention, the end shape on the upstream side of the flow is made to have a small resistance, so that the flow is not hindered. Further, if a plurality of distances between the metal fiber sheet material and the core material on the surface are used, a wide range of frequencies can be absorbed. Further, since it is a metal fiber sheet material that acts as a sound absorbing material, it is not easily deteriorated. In particular, if the material is aluminum, a lightweight sound absorbing structure with excellent corrosion resistance can be obtained. In addition, such a sound absorbing structure can provide a sound absorbing device suitable for installation in an opening having a flow such as an exhaust port.

  Embodiments of the present invention will be described below with reference to the drawings. Note that the materials, configurations, and numerical values described in the following embodiments are examples and can be changed as appropriate.

Fig.1 (a) shows the whole perspective view of one implementation of 1st Embodiment of the sound-absorbing structure of this invention, FIG. 2 shows the sectional drawing. The sound absorbing structure 1 is mainly composed of a corrugated core material 2 and a metal fiber sheet material 3. The metal fiber sheet material 3 surrounds the corrugated core material 2, and the sheet material 3 and the corrugated core material. Both surfaces 2a and 2b and one side surface 2c are in close contact with each other. Here, the both surfaces of the corrugated core material mean two surfaces formed by planes intermittently continuous in the longitudinal direction. Further, the side surface of the corrugated core material refers to a short plane of the end portion of the corrugate. FIG.1 (b) is a perspective view which shows the core material 2, and the core material 2 forms the aluminum plate of thickness 2mm in the shape of a corrugate. FIG.1 (c) is a perspective view which shows the metal fiber sheet material 3, and the metal fiber sheet material 3 shape | molds and rolls the thin fiber about 100 micrometers in diameter in the sheet form, and is about 1 mm thick. The overall dimensions of the sound absorbing structure are a width of 85 mm, a length of 500 mm, and a height of 250 mm. The cross section of the sheet material 3 of the portion 4 facing at least the upstream side of the flow of the sound absorbing structure is not limited to a semicircular shape as shown in FIG. 1 and FIG. Alternatively, both sides may be tapered. By having these shapes, the sound absorbing structure of the present embodiment does not hinder the flow even when arranged in the exhaust port or the like, and therefore does not hinder the exhaust function.
3A is an overall perspective view of a modified embodiment of the first embodiment of the sound absorbing structure of the present invention, FIG. 3B is a perspective view showing the core member 2, and FIG. 3C is this metal. It is a perspective view which shows the fiber sheet material 3. FIG. The cross section of the sheet material 3 of the portion 4 facing at least the upstream side of the flow of the sound absorbing structure is tapered on both sides.

According to the first embodiment of the present invention, it is possible to absorb noise having a frequency determined by the height of the corrugated peak, that is, the distance between the corrugated metal sheet sheet 3 and the core material 2 on the surface. The upstream side of the flow has a shape that does not hinder the flow and has low resistance. Therefore, the exhaust function is not hindered. Since the sound absorbing portion that exhibits the sound absorbing performance is a metal fiber, there is no decrease in the sound absorbing performance due to deterioration, and there is no scattering of the fiber.
Note that the distance between the metal fiber sheet material 3 on the surface and the core material 2 on the back is determined based on the frequency of the sound to be absorbed, with some correction values taken into account.

FIG. 4 shows a sectional view of a second embodiment of the sound absorbing structure of the present invention. FIG. 4A shows a mode in which the corrugated peak height 5 of the core material 2 gradually increases from one end to the other end of the portion 4 facing the upstream side of the flow. FIG. 4B shows a mode in which the corrugated peak height of the core material 2 gradually decreases from one end to the other end of the portion 4 facing the upstream side of the flow. As a result, the corrugated peak height 5 of the core material gradually changes, whereby the width gradually changes, and there are a plurality of types of distances between the metal fiber sheet material 3 on the surface and the corrugation of the core material 2. Thus, noise in a wider frequency range can be absorbed. Other structures, materials, etc. are the same as in the first embodiment.
According to the invention of the second embodiment, it is possible to absorb noise of a plurality of frequencies. In addition, the flow is not disturbed because the width only changes gradually. Therefore, the exhaust function is not hindered.

Fig.5 (a) shows the whole perspective view of one implementation of 3rd Embodiment of the sound-absorbing structure of this invention, FIG. 6 shows the sectional drawing. The sound absorbing structure 1 is mainly composed of a core material 2 composed of a trunk material 11 and a branch material 12, and a metal fiber sheet material 3. The metal fiber sheet material 3 surrounds the core material 2, and the sheet material 3 The branch material 12 tip of the core material 2 and one tip of the branch material 12 are in close contact with each other. FIG.5 (b) is a perspective view which shows the core material 2, and combines the aluminum plate of thickness 2mm. FIG.5 (c) is a perspective view which shows the metal fiber sheet material 3, and the metal fiber sheet material 3 shape | molds and rolls the thin fiber about 100 micrometers in diameter in the sheet form, and is about 1 mm thick. The overall dimensions of the sound absorbing structure 1 are a width of 85 mm, a length of 500 mm, and a height of 250 mm. The cross section of the sheet material 3 of the portion 4 facing at least the upstream side of the flow of the sound absorbing structure 1 is not limited to a semicircular shape as shown in FIGS. Alternatively, both sides may be tapered. By having these shapes, the sound absorbing structure of the present embodiment does not hinder the flow even when arranged in the exhaust port or the like, and therefore does not hinder the exhaust function.
FIG. 7A is an overall perspective view of a modified embodiment of the third embodiment of the sound absorbing structure of the present invention, FIG. 7B is a perspective view showing the core member 2, and FIG. It is a perspective view which shows the fiber sheet material 3. FIG. The cross section of the sheet material 3 of the portion 4 facing at least the upstream side of the flow of the sound absorbing structure is tapered on both sides.
According to the invention of the third embodiment, noise in a higher frequency region can be absorbed even with the same width as compared with the inventions of the first and second embodiments.

FIG. 8 shows a sectional view of a fourth embodiment of the sound absorbing structure of the present invention. In FIG. 8A, the length of the branch 12 portion of the core material 2 is gradually increased from one end to the other end of the portion 4 facing the upstream side of the flow. In FIG. 8B, the length of the branch 12 portion of the core material 2 is gradually reduced from one end to the other end of the portion 4 facing the upstream side of the flow. As a result, the length of the branch portion of the core material changes gradually, the width changes gradually, and there are multiple types of distances between the metal fiber sheet material on the surface and the corrugation of the core material, and a wider frequency range. Can absorb the noise.
According to the fourth embodiment, it is possible to absorb noise of a plurality of frequencies. In addition, the flow is not disturbed because the width only changes gradually. Therefore, the exhaust function is not hindered.

FIG. 9 shows a cross-sectional view of a fifth embodiment of the sound absorbing structure of the present invention. The trunk 11 portion of the core material 2 has a corrugated shape, and the branch material 12 is attached to the bent position. Thereby, the distance of the corrugation of the metal fiber sheet material 3 on the surface and the core material 2 exists, and the noise of a wider frequency range can be absorbed. Further, since the width of the sound absorbing structure 1 is not changed, the flow resistance is not increased.
According to the fifth embodiment of the present invention, it is possible to effectively absorb noise having a plurality of frequencies without increasing the flow resistance.

In addition, the sixth embodiment of the sound absorbing structure of the present invention uses a metal fiber sheet material made of aluminum or an aluminum alloy, formed into a sheet shape, and then sintered and integrated by heating. is doing.
Therefore, according to the invention of the sixth embodiment, it is possible to obtain a sound absorbing structure that is lightweight and excellent in corrosion resistance.

FIG. 10 shows an overall perspective view of the sound absorbing device according to the seventh embodiment of the present invention, and an example of the sound absorbing device in which the sound absorbing structure 1 of the present invention is installed in an opening having a flow inside the exhaust port 21 or the like. It is. Since the sound-absorbing structure 1 is arranged at intervals such that a plane on which the metal fiber sheet material is present is parallel to the flow direction indicated by the arrows, a flow of air or the like passes between them. Moreover, the flow is obstructed by installing the end of the sound-absorbing structure 1 with the metal fiber sheet material having a semicircular, semi-elliptical, one-side taper, or both-side taper toward the upstream side of the flow. Does not disturb the exhaust function.
Therefore, according to the seventh embodiment of the present invention, it is possible to provide a lightweight sound absorbing device that has a small flow resistance, is excellent in sound absorbing performance over a wide range of frequencies, and does not easily deteriorate.

  In the above embodiment, the core material 2 is manufactured by combining the metal plates formed by bending. However, any material can be used as long as the core material 2 can withstand and be supported by the metal fiber sheet material. Alternatively, it may be made of resin. Further, it may be an integral structure such as an extruded aluminum material or a structure in which a plurality of parts are combined.

As the metal fiber sheet material 3 used in the present invention, an aluminum fiber sintered nonwoven fabric can be suitably used. The porosity of the metal fiber sheet material is preferably in the range of 20 to 50%. The mass per unit area (weight per unit area) is preferably in the range of 500 to 3000 g / m ² . Examples of the aluminum fiber sintered nonwoven fabric satisfying such a preferable condition include “full porous” (registered trademark, manufactured by Furukawa Sky Co., Ltd.).

  Further, the metal fiber sheet material 3 and the core material 2 may be joined by any method. For example, if the same metal is used, spot welding may be used, riveting may be used, or an adhesive may be used. However, it is necessary to withstand deterioration due to the flow and environment in the installation place such as the exhaust port of the core material 2 and the metal fiber sheet material 3. Therefore, the metal fiber can be coated within a range where the sound absorption performance does not deteriorate, or a corrosion-resistant film can be applied. In the case where the metal fiber sheet material 3 and the core material 2 are aluminum or an aluminum alloy, the surface can be subjected to alumite or boehmite treatment to improve the corrosion resistance. The material of aluminum or aluminum alloy is preferably determined in consideration of mass productivity, workability, sound absorption performance, and the like.

Table 1 shows the sound absorption performance, flow resistance, dust generation, anti-deterioration, low cost, space saving, and lightness of the structures of the first to sixth embodiments of the present invention and the conventional sound absorbing structures. A comparative evaluation is shown for each item. here,
As a conventional example, the conventional example 1 is a glass wool sound absorbing type, the conventional example 2 is a reactive type (Helmholtz resonator), the conventional example 3 is an active type (speaker antiphase canceling structure), and the conventional example 4 is used. As a sound absorbing panel described in Japanese Patent Application Laid-Open No. 2001-166780 (referred to as “Document 1” in Table 1).
In addition, in each of the sound absorbing structures of the present invention, the cross section of the sheet material at the portion facing the upstream side of the flow (“end shape” in Table 1) is for a taper on both sides. ,
◎ is the result of evaluation of the conventional example 4 of the conventional examples, that is, the evaluation results for those clearly superior to this, based on the sound absorbing panel of Document 1.
○ is the evaluation result for what is considered to be almost equivalent to the sound absorption panel of Conventional Example 4, that is, Reference 1,
X is the evaluation result for the example 4 that is clearly inferior to this with reference to the sound absorption panel of Conventional Example 4, that is, Document 1.
Respectively.
However, the evaluation of “flow resistance” was based on qualitative superiority or inferiority such that a wider frequency can be absorbed rather than the sound absorption level. In addition, only the “flow resistance” of the evaluation items was based on the reactive type of Conventional Example 2 as the evaluation standard.

  As shown in Table 1, the sound absorbing structure of the conventional example has x in the evaluation items among the above evaluations, while the sound absorbing structure of the present invention satisfies all the evaluations. It is an excellent sound absorbing structure.

1 is an overall perspective view of a first embodiment of a sound absorbing structure according to the present invention. It is sectional drawing of 1st Embodiment of the sound-absorbing structure of this invention. It is a whole perspective view of the deformation | transformation aspect of 1st Embodiment of the sound-absorbing structure of this invention. It is sectional drawing of 2nd Embodiment of the sound-absorbing structure of this invention. It is a whole perspective view of 3rd Embodiment of the sound-absorbing structure of this invention. It is sectional drawing of 3rd Embodiment of the sound-absorbing structure of this invention. It is a whole perspective view of the deformation | transformation aspect of 3rd Embodiment of the sound-absorbing structure of this invention. It is sectional drawing of 4th Embodiment of the sound-absorbing structure of this invention. It is sectional drawing of 5th Embodiment of the sound-absorbing structure of this invention. It is a whole perspective view of the sound-absorbing device of 7th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sound absorption structure 2 Core material 3 Metal fiber sheet material 4 The part which faces the upstream of the flow 5 Corrugated peak height 11 Trunk material 12 Branch material 21 Exhaust port

Claims (7)

  The metal fiber sheet material is attached to both surfaces and at least one side surface of the corrugated core material, the metal fiber sheet material is in close contact with both surfaces of the core material, and the side surface of the core material on which the metal fiber sheet material exists The cross-sectional shape of the metal fiber sheet material is semicircular, semi-elliptical, one-side tapered or both-side tapered, and the side surface having the cross-sectional shape is installed toward the upstream side of the flow. Characteristic sound absorbing structure.   The sound absorbing structure according to claim 1, wherein a width of the core material is gradually changed by gradually changing a corrugated peak height of the core material.   The core material has a shape composed of a trunk and a branch, and the metal fiber sheet material is attached in close contact with at least one tip and a branch tip of the trunk of the core material, and the metal fiber sheet material is the core material. The metal fiber sheet material has a semicircular, semi-elliptical, one-sided taper, or double-sided taper on the tip side of the trunk where the metal fiber sheet material is in close contact, and the tip side having the cross-sectional shape flows. It is installed and used toward the upstream side of the sound absorbing structure.   The sound absorbing structure according to claim 3, wherein the width of the branch portion of the core material is gradually changed by gradually changing the length of the branch portion.   The sound-absorbing structure according to claim 3, wherein there are a plurality of types of distances between the metal fiber sheet material and the trunk of the core material because the trunk of the core material has a corrugated shape.   The material of the metal fiber sheet material is aluminum or an aluminum alloy, and after molding them into a sheet shape, a sintered and integrated material is used. The sound absorbing structure as described.   The sound-absorbing structure according to any one of claims 1 to 6, wherein the sound-absorbing structure is disposed at an opening having a flow at an interval so that a plane with the metal fiber sheet material is substantially parallel to the flow direction. A sound absorbing device.

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