WO2020188767A1

WO2020188767A1 - Sound absorption equipment

Info

Publication number: WO2020188767A1
Application number: PCT/JP2019/011541
Authority: WO
Inventors: 誠谷島; 洋次尾中; 教将上村; 宏紀福岡
Original assignee: 三菱電機株式会社
Priority date: 2019-03-19
Filing date: 2019-03-19
Publication date: 2020-09-24
Also published as: JPWO2020188767A1; JP6593835B1

Abstract

This sound absorption equipment is provided with a sound absorption material and a fastening part for fastening the sound absorption material to a mounting surface. The sound absorption material comprises a porous material with a first surface and a second surface, and a membranous body overlapping the first surface. The membranous body has a plurality of through-holes. The distance between each of the plurality of through-holes is greater than the inner diameter of each through-hole. The fastening part dents the membranous body and the first surface toward the mounting surface at a press position away from each of the plurality of through-holes to thus fix the sound absorption material to the mounting surface.

Description

Sound absorber

The present invention relates to a sound absorbing device.

Conventionally, in order to reduce the noise in the sound field, a perforated plate is opposed to the wall in the sound field, and the air layer existing between the wall in the sound field and the perforated plate is divided into a plurality of tubular voids by a partition wall. A structure has been proposed (see, for example, Patent Document 1).

JP-A-2007-11034

However, in the conventional sound absorbing structure shown in Patent Document 1, it is necessary to partition the air layer into a plurality of tubular voids by an expensive partition wall. Therefore, the conventional sound absorbing structure shown in Patent Document 1 is costly.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a sound absorbing device capable of improving sound absorbing performance and reducing costs.

The sound absorbing device according to the present invention has a porous member on which the first surface and the second surface are formed, a film-like body on which the first surface is formed, and a sound absorbing member on which the second surface overlaps the installation surface. A fixing member for fixing the sound absorbing member to the installation surface is provided, and a plurality of through holes are formed in the film-like body, and the distance between each of the plurality of through holes is larger than the inner diameter of each through hole. In the fixing member, the film-like body and the first surface are recessed toward the installation surface at a holding position away from each of the plurality of through holes, and the sound absorbing member is fixed to the installation surface.

According to the sound absorbing device according to the present invention, the sound absorbing performance can be improved and the cost can be reduced.

It is a perspective view which shows the sound absorbing apparatus according to Embodiment 1 of this invention. It is sectional drawing along the line II-II of FIG. It is a schematic enlarged sectional view which shows the sound absorbing member of FIG. It is a model diagram which shows by modeling the sound absorbing member of FIG. 3 into a plurality of elements. It is a perspective view which shows the sound absorbing device which represented a plurality of virtual walls in the sound absorbing member of FIG. It is sectional drawing along the VI-VI line of FIG. It is a perspective view which shows the state which the plurality of pins of FIG. 1 are fixed to the installation surface. It is a graph which compared the relationship between the sound absorption coefficient α and the sound frequency F in Example and Comparative Example. It is a graph which compared the relationship between the sound absorption coefficient α and the sound frequency F in Example 1A and Example 1B. It is a graph which compared the relationship between the sound absorption coefficient α and the sound frequency F in Example 1C, Example 1D, and Example 1E. It is a perspective view which shows another example of the sound absorbing apparatus according to Embodiment 1 of this invention. It is a perspective view which shows the sound absorbing apparatus according to Embodiment 2 of this invention. It is sectional drawing along the XIII-XIII line of FIG. It is an enlarged top view which shows the positional relationship of the adhesive layer with respect to the micropores in the sample of condition 1. FIG. It is an enlarged top view which shows the positional relationship of the adhesive layer with respect to the micropores in the sample of condition 2. It is an enlarged top view which shows the positional relationship of the adhesive layer with respect to the micropores in the sample of condition 3. It is an enlarged top view which shows the position of the micropore in the sample of condition 4. 6 is a graph comparing the relationship between the sound absorption coefficient α and the sound frequency F in each of the samples of conditions 1 to 4. It is a perspective view which shows the sound absorbing apparatus according to Embodiment 3 of this invention. It is a perspective view which shows the sound absorbing apparatus according to Embodiment 4 of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1.
FIG. 1 is a perspective view showing a sound absorbing device according to a first embodiment of the present invention. Further, FIG. 2 is a cross-sectional view taken along the line II-II of FIG. The sound absorbing device 1 is provided in a housing 2 of a device that is a noise source, such as a fan of an air conditioner and a hoisting machine of an elevator. The sound generated by the device that is a noise source is absorbed by the sound absorbing device 1.

The housing 2 has a bottom plate 21 and a side plate 22 provided along the outer peripheral portion of the bottom plate 21. In the housing 2, an opening 23 is formed by an edge portion of a side plate 22. The bottom plate 21 is formed with an installation surface 24 exposed to the space inside the housing 2.

The sound absorbing device 1 is fixed to the installation surface 24. Further, the sound absorbing device 1 has a sound absorbing member 3 and a plurality of pins 4 as a plurality of fixing members for fixing the sound absorbing member 3 to the installation surface 24.

The sound absorbing member 3 has a porous member 5 and a perforated plate (MPP: MicroPerforated Panel) 6 overlapping the porous member 5. In this example, the sound absorbing member 3 has a plate shape. Further, in this example, the thickness direction Z of the sound absorbing member 3 coincides with the direction orthogonal to the installation surface 24.

As shown in FIG. 2, the porous member 5 is formed with a first surface 51 and a second surface 52 facing each other. In this example, the first surface 51 and the second surface 52 face each other in the thickness direction Z of the porous member 5. The perforated plate 6 overlaps the first surface 51. The second surface 52 overlaps the installation surface 24.

A plurality of continuous pores are formed inside the porous member 5. As a result, the porous member 5 is a breathable member. Further, the porous member 5 is made of an elastic material. As a result, the porous member 5 can be elastically deformed by receiving an external force.

As the porous member 5, a foam, a fiber aggregate, or the like is used. The foam is a member formed into a foam by finely dispersing gas in rubber or resin. Examples of the foam include urethane foam. A fiber assembly is a member composed of fibers that are intertwined with each other. In the fiber aggregate, gaps as pores are formed between the fibers entwined with each other. Examples of the fiber aggregate include glass wool, rock wool, and non-woven fabric.

The perforated plate 6 is a film-like body in which a plurality of micropores 61 are formed as a plurality of through holes. In this example, a film is used as the film-like body. Therefore, in this example, a film in which a plurality of micropores 61 are formed is used as the perforated plate 6.

Examples of the film material used for the perforated plate 6 include polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and the like. Further, in this example, the thickness of the perforated plate 6 is set to several tens of μm. Further, in this example, the ratio of the total area of the plurality of micropores 61 to the area of the perforated plate 6, that is, the opening ratio of the micropores 61 is about 0.05% to 16%. In this example, the cross-sectional shape of each micropore 61 is circular.

The plurality of micropores 61 are formed in the film at intervals from each other. In this example, N fine holes 61 are located at equal intervals in the width direction X of the sound absorbing member 3, and M fine holes 61 are located at equal intervals in the depth direction Y of the sound absorbing member 3. However, the width direction X of the sound absorbing member 3 and the depth direction Y of the sound absorbing member 3 are both orthogonal to the thickness direction Z of the sound absorbing member 3. The width direction X of the sound absorbing member 3 is a direction orthogonal to the depth direction Y of the sound absorbing member 3. Further, N and M are both integers of 1 or more.

The distance between each of the plurality of micropores 61 is larger than the inner diameter of each micropore 61. Therefore, the distance between the micropores 61 is larger than the inner diameter of the micropores 61 in both the width direction X and the depth direction Y of the sound absorbing member 3. The distance between the two micropores 61 adjacent to each other is the size of the film-like body interposed between the two micropores 61.

Protrusions 62 protruding from the film-like body are formed on the peripheral edges of each of the micropores 61. Each protrusion 62 projects from the film-like body to the side opposite to the porous member 5 side. Further, each protrusion 62 is arranged over the entire circumference of the microhole 61. As a result, the protrusion 62 surrounds the space inside the microhole 61. In this example, micropores 61 are formed in the film by piercing the film with a needle. Further, in this example, a part of the film is extruded by a needle pierced by the film, and a deformed burr is formed on the film as a protrusion 62.

Here, as shown in FIG. 1, the center-to-center distance of each microhole 61 in the width direction X of the sound absorbing member 3 is defined as the microhole distance a in the width direction X. In this case, the width dimension W1 of the perforated plate 6 is represented by N × a. Further, the distance between the centers of the micropores 61 in the depth direction Y of the sound absorbing member 3 is defined as the interpupillary distance b in the depth direction Y. In this case, the depth dimension W2 of the perforated plate 6 is represented by M × b. Further, the thickness of the porous member 5 is defined as the thickness c of the porous member. Further, the total thickness of the perforated plate 6 and the protrusion 62 is defined as the fine hole forming thickness t.

The frequencies absorbed by the sound absorbing member 3 are the interpupillary distance a in the width direction X, the interpupillary distance b in the depth direction Y, the thickness c of the porous member, the inner diameter d of the micropores 61, and the micropore forming thickness t. It changes when at least one changes. That is, if at least one of the interpupillary distance a in the width direction X, the interpupillary distance b in the depth direction Y, the thickness c of the porous member, the inner diameter d of the micropores 61, and the micropore formation thickness t is reduced, The frequency of sound absorption by the sound absorbing member 3 changes to the high frequency side. Further, when at least one of the interpupillary distance a in the width direction X, the interpupillary distance b in the depth direction Y, the thickness c of the porous member, the inner diameter d of the micropores 61, and the micropore formation thickness t is increased, The frequency of sound absorption by the sound absorbing member 3 changes to the low frequency side.

Therefore, in order to secure high sound absorption performance in a narrow band as the sound absorption performance of the sound absorbing member 3, the interpupillary distance a in the width direction X is made constant between the micropores 61, and the interpupillary distance in the depth direction Y. It is preferable to make b constant among the micropores 61. On the other hand, when the sound absorption performance in a wide band is ensured as the sound absorption performance of the perforated plate 6 even if the sound absorption performance deteriorates, the interpupillary distance a in the width direction X and the interpupillary distance b in the depth direction Y It is preferable to arrange a plurality of sound absorbing members 3 and fix them to the installation surface 24 so that at least one of the above is different for each sound absorbing member 3. The interpupillary distance a in the width direction X may be the same as the interpupillary distance b in the depth direction Y, or may be different from the interpupillary distance b in the depth direction Y.

FIG. 3 is a schematic enlarged cross-sectional view showing the sound absorbing member 3 of FIG. Further, FIG. 4 is a model diagram showing the sound absorbing member 3 of FIG. 3 modeled into a plurality of elements. The sound absorbing member 3 is represented by a vibration model of a one-degree-of-freedom system in which the mass 201 is connected to the installation surface 24 via the spring 202 and the damper 203. That is, in the vibration model of the sound absorbing member 3, the air inside the micropores 61 has a mass of 201. Further, in the vibration model of the sound absorbing member 3, the air layer in which the porous member 5 is arranged acts as a spring 202, and the viscous resistance when air passes through the micropores 61 and the porous member 5, that is, the flow of air. The resistor acts as a damper 203.

Therefore, the sound absorption coefficient α of the sound absorbing member 3 can be increased by adjusting the value of the viscous resistance of the damper 203. The value of the viscous resistance of the damper 203 can be adjusted by the porous member 5. Therefore, the air flow resistance in the porous member 5 is an important parameter for increasing the sound absorption coefficient α.

The sound absorption coefficient α of the sound absorbing member 3 becomes maximum when the frequency of the sound incident from each of the fine holes 61 matches the resonance frequency of the perforated plate 6. Further, the sound absorption coefficient α of the sound absorbing member 3 decreases as the frequency of the sound incident from each of the micropores 61 deviates from the resonance frequency of the perforated plate 6. The sound absorption coefficient α of the sound absorbing member 3 is represented by the following equation (1).

However, Z _total is the total impedance of the perforated plate 6 and the porous member 5.

When sound is incident on the porous member 5 from each of the micropores 61, sound waves radiate from the micropores 61 toward the installation surface 24 inside the porous member 5. As a result, the sound waves incident on the inside of the porous member 5 from each of the micropores 61 interfere with each other at the positions of a plurality of virtual walls that do not actually exist. In the sound absorbing member 3, sound waves interfere with each other at the positions of the virtual walls, so that sound absorbing performance similar to that of an actual partition wall at the positions of the virtual walls can be obtained.

FIG. 5 is a perspective view showing a sound absorbing device 1 representing a plurality of virtual walls in the sound absorbing member 3 of FIG. The sound absorbing member 3 includes a plurality of first virtual walls 71 orthogonal to the depth direction Y of the sound absorbing member 3 and a plurality of second virtual walls 72 orthogonal to the width direction X of the sound absorbing member 3 as a plurality of virtual walls 7. expressed. The first virtual wall 71 and the second virtual wall 72 intersect each other at a position deviating from the position of each microhole 61.

Each virtual wall 7 is located between two microholes 61 adjacent to each other. Specifically, each first virtual wall 71 is located between two microholes 61 adjacent to each other in the depth direction Y of the sound absorbing member 3, and two microholes 61 adjacent to each other in the width direction X of the sound absorbing member 3. Each second virtual wall 72 is located between the two.

Further, the distances from each of the two microholes 61 adjacent to each other to the virtual wall 7 are equal to each other. Specifically, the distances from each of the two microholes 61 adjacent to each other in the depth direction Y of the sound absorbing member 3 to the first virtual wall 71 are equal to each other, and 2 adjacent to each other in the width direction X of the sound absorbing member 3. The distances from each of the micropores 61 to the second virtual wall 72 are equal to each other.

In the perforation plate 6, a plurality of first virtual center lines 71a and a plurality of second virtual center lines 72a are set as a plurality of virtual center lines 7a.

Each first virtual center line 71a is set at a position where the perforated plate 6 and each first virtual wall 71 intersect. Each second virtual center line 72a is set at a position where the perforated plate 6 and each second virtual wall 72 intersect.

As a result, each virtual center line 7a is located between two microholes 61 adjacent to each other. That is, each first virtual center line 71a is located between two microholes 61 adjacent to each other in the depth direction Y of the sound absorbing member 3, and between two microholes 61 adjacent to each other in the width direction X of the sound absorbing member 3. Each second virtual center line 72a is located at.

Further, the distances from each of the two microholes 61 adjacent to each other to the virtual center line 7a are equal to each other. That is, the distances from each of the two microholes 61 adjacent to each other in the depth direction Y of the sound absorbing member 3 to the first virtual center line 71a are equal to each other, and the two adjacent microholes 61 in the width direction X of the sound absorbing member 3 are adjacent to each other. The distances from each of the micropores 61 to the second virtual center line 72a are equal to each other.

The plurality of pins 4 hold the sound absorbing member 3 toward the installation surface 24 at a holding position away from each of the plurality of microholes 61. The holding position of each pin 4 is set on the virtual center line 7a. In this example, the holding position of each pin 4 is set at the position of the intersection of the first virtual center line 71a and the second virtual center line 72a. Therefore, in this example, as shown in FIG. 1, the sound absorbing member 3 is separated from the center of the microhole 61 by a distance P1 which is 1/2 of the interpupillary distance a in the depth direction Y, and the sound is absorbed from the center of the microhole 61. The holding position of the pin 4 is set at a position separated by a distance P2 of 1/2 of the interpupillary distance b in the width direction X of the member 3.

FIG. 6 is a cross-sectional view taken along the VI-VI line of FIG. Each pin 4 has a rod-shaped penetrating portion 41 penetrating the sound absorbing member 3, a connecting portion 42 provided at one end of the penetrating portion 41, and a pressing portion 43 provided at the other end of the penetrating portion 41. are doing.

The penetrating portion 41 is arranged along the thickness direction Z of the sound absorbing member 3. In this example, the penetration portion 41 is arranged on the intersection of the first virtual wall 71 and the second virtual wall 72. As a result, the influence of the pin 4 on the sound waves incident on the inside of the porous member 5 from each of the micropores 61 is reduced.

The connection portion 42 is connected to the installation surface 24. In this example, the shape of the connecting portion 42 is a flange shape extending in the radial direction from one end of the penetrating portion 41. As a result, the connection state of the pin 4 with respect to the installation surface 24 is stabilized.

The holding portion 43 is exposed to the outside from the sound absorbing member 3. Further, the pressing portion 43 is a rod-shaped portion that projects laterally from the penetrating portion 41 from the other end portion of the penetrating portion 41. Each pin 4 presses the sound absorbing member 3 on the installation surface 24 by the pressing portion 43. In this example, as shown in FIG. 5, when the pin 4 is viewed along the thickness direction Z of the sound absorbing member 3, each holding portion 43 is arranged on the first virtual center line 71a.

The perforated plate 6 and the first surface 51 are recessed toward the installation surface 24 by being pressed by the pressing portion 43. That is, each pin 4 has the perforated plate 6 and the first surface 51 recessed toward the installation surface 24 by pressing the sound absorbing member 3 with the pressing portion 43. In the porous member 5, the first surface 51 is recessed and elastically deformed to generate an elastic restoring force toward the perforated plate 6. The perforated plate 6 receives the elastic restoring force of the porous member 5 to generate tension in the direction of the arrow in FIG. 6 orthogonal to the thickness direction of the perforated plate 6.

Next, the manufacturing method of the sound absorbing device 1 will be described. FIG. 7 is a perspective view showing a state in which the plurality of pins 4 of FIG. 1 are fixed to the installation surface 24. When the sound absorbing device 1 is manufactured, the sound absorbing member 3 is manufactured in advance by superimposing the perforated plate 6 on the first surface 51 of the porous member 5. The plurality of micropores 61 are formed by piercing the film with a needle. As a result, a protrusion 62 formed by extruding a part of the film is formed on the peripheral edge of each of the micropores 61.

If the perforated plate 6 is superposed on the porous member 5 with the protrusion 62 facing the porous member 5, a gap is generated between the porous member 5 and the perforated plate 6 by the height of the protrusion 62. .. Therefore, when the sound absorbing member 3 is manufactured, each protrusion 62 is perforated toward the side opposite to the porous member 5 side in order to prevent a gap from being formed between the porous member 5 and the perforated plate 6. The plate 6 is superposed on the first surface 51 of the porous member 5.

When manufacturing the sound absorbing device 1, first, a plurality of pins 4 are fixed to the installation surface 24. At this time, the flange-shaped connecting portion 42 is connected to the installation surface 24. Further, at this time, each pin 4 is formed with a straight rod-shaped portion in which the penetrating portion 41 and the pressing portion 43 are not bent. The length of the straight rod-shaped portion of each pin 4 is longer than the total length of the thickness of the porous member 5 and the thickness of the perforated plate 6.

After that, the sound absorbing member 3 is placed on the installation surface 24. At this time, the sound absorbing member 3 is pushed into the installation surface 24 while inserting the straight rod-shaped portions of the pins 4 in the order of the porous member 5 and the perforated plate 6. As a result, the straight rod-shaped portion of each pin 4 penetrates the sound absorbing member 3, and a part of the straight rod-shaped portion of each pin 4 protrudes from the sound absorbing member 3. At this time, the straight rod-shaped portion of each pin 4 pushes through the film of the perforated plate 6. As a result, burrs that adhere to the outer peripheral surface of the straight rod-shaped portion of each pin 4 are formed on the film. Therefore, the contact area between the perforated plate 6 and each pin 4 is increased, and the perforated plate 6 is suppressed from slipping with respect to each pin 4.

After that, at a position where a part of each pin 4 protrudes from the sound absorbing member 3, the sound absorbing member 3 is pushed toward the installation surface 24 to dent the perforated plate 6 and the first surface 51. At this time, the porous member 5 is elastically deformed around each pin 4.

After that, with the perforated plate 6 and the first surface 51 recessed toward the installation surface 24, the portion of the straight rod-shaped portion of each pin 4 protruding from the sound absorbing member 3 is bent. As a result, of the straight rod-shaped portions of each pin 4, the portion penetrating the sound absorbing member 3 becomes the penetrating portion 41, and the portion exposed to the outside from the sound absorbing member 3 and bent becomes the pressing portion 43. As a result, the sound absorbing member 3 is fixed to the installation surface 24. The state in which the perforated plate 6 and the first surface 51 are recessed toward the installation surface 24 is maintained by pressing the sound absorbing member 3 by the pressing portion 43. In this way, the sound absorbing device 1 is manufactured.

In such a sound absorbing device 1, each pin 4 recesses the perforated plate 6 and the first surface 51 toward the installation surface 24 at a holding position away from each microhole 61, and fixes the sound absorbing member 3 to the installation surface 24. To do. Therefore, tension can be generated in the perforated plate 6, and the perforated plate 6 can be more reliably adhered to the porous member 5. As a result, the sound absorbing coefficient α of the sound absorbing member 3 can be improved, and the sound absorbing performance of the sound absorbing device 1 can be improved. Further, it is not necessary to use the porous member 5 as an expensive partition wall. Therefore, the cost of the sound absorbing device 1 can be reduced.

Here, the relationship between the sound absorption coefficient α and the sound frequency F [Hz] was compared between the example and the comparative example. In the embodiment, as in the first embodiment, the sound absorbing member 3 is fixed to the installation surface 24 by each pin 4, and the perforated plate 6 and the first surface 51 are recessed toward the installation surface 24 by each pin 4. .. On the other hand, in the comparative example, the sound absorbing member 3 is fixed to the installation surface 24 without using each pin 4 in a state where there is a gap between the perforated plate 6 and the porous member 5. In the examples and comparative examples, the vertically incident sound absorption coefficient measured by the acoustic tube was defined as the sound absorption coefficient α.

FIG. 8 is a graph comparing the relationship between the sound absorption coefficient α and the sound frequency F between the example and the comparative example. In FIG. 8, an embodiment is shown by a solid line, and a comparative example is shown by a broken line. As shown in FIG. 8, it can be seen that in the examples, the sound absorption coefficient α is larger than that in the comparative example. Therefore, it can be seen that the configuration in which the perforated plate 6 and the first surface 51 are recessed toward the installation surface 24 by each pin 4 contributes to the improvement of the sound absorbing performance of the sound absorbing device 1.

Further, the sound absorbing member 3 is fixed to the installation surface 24 by a plurality of pins 4 penetrating the sound absorbing member 3. Therefore, the sound absorbing member 3 can be easily fixed to the installation surface 24.

Further, the pressing position for pressing the sound absorbing member 3 by the pin 4 is set on the virtual center line 7a in which the distances from each of the two adjacent microholes 61 are equal. Therefore, it is possible to more reliably improve the sound absorption coefficient α of the sound absorbing device 1.

Here, in Example 1A where the holding position of the pin 4 is on the virtual center line 7a, and in Example 1B where the holding position of the pin 4 is closer to the microhole 61 than the position on the virtual center line 7a. The relationship between the sound absorption coefficient α and the sound frequency F [Hz] was compared.

FIG. 9 is a graph comparing the relationship between the sound absorption coefficient α and the sound frequency F between Example 1A and Example 1B. As shown in FIG. 9, it can be seen that the sound absorption coefficient α of Example 1A is higher than the sound absorption coefficient α of Example 1B. From this, it can be seen that the configuration in which the holding position of the pin 4 is on the virtual center line 7a contributes to the improvement of the sound absorbing performance of the sound absorbing device 1. When the holding position of the pin 4 deviates from the virtual center line 7a and is close to the fine hole 61, the impedance inside the porous member 5 changes, so that the sound absorbing performance around the pin 4 tends to deteriorate. ..

Further, on the peripheral edge of each of the micropores 61, a protrusion 62 is formed so as to project from the film-like body to the side opposite to the porous member 5 side. Therefore, it is possible to prevent the protrusion 62 from interposing between the perforated plate 6 and the porous member 5. As a result, the perforated plate 6 can be more reliably adhered to the porous member 5.

Here, Example 1C in which the perforated plate 6 has no protrusion 62, Example 1D in which the height of the protrusion 62 is 0.1 [mm], and the height of the protrusion 62 is 0.2 [mm]. In Example 1E, the relationship between the sound absorption coefficient α and the sound frequency F [Hz] was compared.

FIG. 10 is a graph comparing the relationship between the sound absorption coefficient α and the sound frequency F between Example 1C, Example 1D, and Example 1E. As shown in FIG. 10, in the sound absorbing member 3, it can be seen that the frequency of the sound having the maximum sound absorbing coefficient shifts to the low frequency side as the height of the protrusion 62 increases. Further, in the sound absorbing member 3, it can be seen that the maximum sound absorbing coefficient of the sound absorbing member 3 increases as the height of the protrusion 62 increases.

In this way, by lengthening the depth of the microhole 61 by the protrusion 62, the frequency of the sound having the maximum sound absorption coefficient can be shifted to the low frequency side where sound absorption is difficult. Further, the frictional energy between the air passing through the micropores 61 and the inner surface of the micropores 61 increases, and the vibration energy of sound can be easily converted into heat energy. Thereby, the maximum sound absorption coefficient of the sound absorbing member 3 can be improved. Therefore, by providing the protrusion 62 on the peripheral edge of each of the micropores 61, it is possible to further reliably improve the sound absorbing performance of the sound absorbing device 1.

In the first embodiment, the holding portions 43 of the two pins 4 adjacent to each other on the common virtual center line 7a are separated from each other. However, as shown in FIG. 11, the holding portions 43 of the two pins 4 adjacent to each other on the common virtual center line 7a may have a portion overlapping with each other. In this case, assuming that the distance between the penetrating portions 41 of the two pins 4 adjacent to each other on the common virtual center line 7a is d, the length of each holding portion 43 of the two pins 4 is d / 2. Will be longer than. By doing so, the range in which the sound absorbing member 3 is pressed by each pin 4 can be widened, and the sound absorbing performance of the sound absorbing device 1 can be further improved.

In FIG. 11, the holding portion 43 of each pin 4 is arranged along the width direction X. However, the holding portion 43 of each pin 4 may be arranged along the depth direction Y.

Further, in the first embodiment, the plurality of micropores 61 are located on a straight line along the width direction X and on a straight line along the depth direction Y. However, the positions of the plurality of micropores 61 may be set in a staggered manner alternately deviated from a straight line along the depth direction Y in the width direction X. Further, the positions of the plurality of micropores 61 may be set in a staggered manner alternately deviated from a straight line along the width direction X in the depth direction Y.

Embodiment 2.
FIG. 12 is a perspective view showing a sound absorbing device according to a second embodiment of the present invention. Further, FIG. 13 is a cross-sectional view taken along the line XIII-XIII of FIG. The sound absorbing member 3 has an adhesive layer 8 interposed between the perforated plate 6 and the porous member 5. The adhesive layer 8 adheres the perforated plate 6 to the first surface 51 of the porous member 5. Further, the adhesive layer 8 is arranged so as to avoid the fine holes 61 when the sound absorbing member 3 is viewed along the direction in which the perforated plate 6 and the porous member 5 overlap. As a result, it is avoided that the ventilation resistance in each of the fine holes 61 becomes excessively large, and the deterioration of the sound absorbing performance of the sound absorbing member 3 is suppressed. As the adhesive layer 8, a double-sided adhesive tape, a resin-based adhesive, or the like is used. Other configurations are the same as those in the first embodiment.

In such a sound absorbing device 1, an adhesive layer 8 is interposed between the perforated plate 6 and the first surface 51 of the porous member 5. Therefore, it is possible to prevent a gap from being formed between the perforated plate 6 and the first surface 51. As a result, the sound absorbing performance of the sound absorbing device 1 can be further improved.

Here, the adhesive layer 8 is not interposed between the sample of the sound absorbing member 3 under conditions 1 to 3 in which the positional relationship of the adhesive layer 8 with respect to each micropore 61 is different from each other, and the perforated plate 6 and the porous member 5. A sample of the sound absorbing member 3 of the condition 4 was prepared, and the sound absorbing coefficient α of each of the samples of the conditions 1 to 4 was measured.

FIG. 14 is an enlarged top view showing the positional relationship of the adhesive layer 8 with respect to the micropores 61 in the sample under condition 1. The adhesive layer 8 has a plurality of adhesive portions 81 arranged along the depth direction Y. In the sample of condition 1, the fine holes 61 and the adhesive portion 81 are alternately arranged in the width direction X. As a result, in the sample of condition 1, when the sound absorbing member 3 is viewed along the direction in which the perforated plate 6 overlaps the porous member 5, a plurality of adhesive portions 81 are formed at positions sandwiching the micropores 61 from both sides in the width direction X. Have been placed. In the sample of condition 1, the peripheral edge of the micropore 61 is in contact with the adhesive portions 81 on both sides. Further, in the sample of condition 1, the sound absorbing member 3 is fixed to the installation surface 24 without using each pin 4. Other configurations are the same as those in the first embodiment.

FIG. 15 is an enlarged top view showing the positional relationship of the adhesive layer 8 with respect to the micropores 61 in the sample under condition 2. The width of each adhesive portion 81 in the sample of condition 2 is 1/2 of the width of each adhesive portion 81 in the sample of condition 1. In the sample of condition 2, each micropore 61 is not in contact with each adhesive portion 81. Other configurations are the same as the sample of condition 1.

FIG. 16 is an enlarged top view showing the positional relationship of the adhesive layer 8 with respect to the micropores 61 in the sample under condition 3. In the sample of the condition 3, the adhesive portions 81 are arranged only at the positions specified in every other row among the positions of the plurality of adhesive portions 81 arranged in the width direction X in the sample of the condition 1. As a result, in the sample of condition 3, when the sound absorbing member 3 is viewed along the direction in which the perforated plate 6 overlaps the porous member 5, the adhesive portion is formed only on one of both sides of each of the micropores 61 in the width direction X. 81 is arranged. Further, in the sample of condition 3, the peripheral edge portion of the micropore 61 is in contact with the adjacent adhesive portion 81. Other configurations are the same as the sample of condition 1.

FIG. 17 is an enlarged top view showing the positions of the micropores 61 in the sample under condition 4. In the sample of condition 4, the adhesive layer 8 is not interposed between the perforated plate 6 and the porous member 5. Other configurations are the same as the sample of condition 1.

FIG. 18 is a graph comparing the relationship between the sound absorption coefficient α and the sound frequency F in each of the samples of conditions 1 to 4. As shown in FIG. 18, among the samples of the conditions 1 to 4, the sample from which the maximum sound absorption coefficient can be obtained is the sample of the condition 1. The maximum sound absorption coefficient of the sample under condition 2 is lower than that of the sample under condition 1. However, in the sample under condition 2, the sound absorption coefficient α is slightly wider than that in the sample under condition 1. On the other hand, in the samples of condition 3 and condition 4, the sound absorption coefficient α is significantly lower than that of the samples of condition 1 and condition 2.

Comparing the sample of condition 2 and the sample of condition 3, the total area of each adhesive portion 81 included in the adhesive layer 8 is almost the same in the samples of condition 2 and condition 3. However, the sound absorption coefficient α is higher in the sample under condition 2 than in the sample under condition 3. From this, it can be seen that the configuration in which the plurality of adhesive portions 81 are located at positions sandwiching the micropores 61 contributes to the improvement of the sound absorbing performance of the sound absorbing device 1. Further, the maximum sound absorption coefficient is higher in the sample under condition 1 than in the sample under condition 2. From this, it can be seen that the configuration in which the adhesive portion 81 is located at a position in contact with the peripheral edge portion of the microhole 61 also contributes to the improvement of the sound absorbing performance of the sound absorbing device 1.

In this way, when the sound absorbing member 3 is viewed in the direction in which the perforated plate 6 overlaps the porous member 5, the sound absorbing performance of the sound absorbing device 1 is further improved by arranging the plurality of adhesive portions 81 at positions sandwiching the fine holes 61. It can be definitely improved.

Further, the sound absorbing performance of the sound absorbing device 1 is further improved by arranging the adhesive portion 81 at a position where the adhesive portion 81 is in contact with the peripheral edge portion of each of the micropores 61 when the sound absorbing member 3 is viewed in the direction in which the perforated plate 6 overlaps the porous member 5. It can be definitely improved.

The sound absorption coefficient α of each of the samples under conditions 1 to 3 is higher than that of the sample under condition 4. Therefore, by applying the fixed configuration by each pin 4 of the first embodiment to each of the samples of the conditions 1 to 3, the sound absorbing performance of the sound absorbing device 1 can be further reliably improved. That is, the sound absorbing device 1 is formed by recessing the perforated plate 6 and the first surface 51 toward the installation surface 24 by each pin 4 and fixing the samples of the sound absorbing members 3 under the conditions 1 to 3 to the installation surface 24. The sound absorption performance of the above can be improved more reliably.

The arrangement of the plurality of adhesive portions 81 is not limited to the arrangement in the samples of conditions 1 to 3, and if the plurality of adhesive portions 81 are arranged while avoiding the micropores 61, the positions of the respective adhesive portions 81 are arranged. Whatever you do.

Embodiment 3.
FIG. 19 is a perspective view showing a sound absorbing device according to a third embodiment of the present invention. The sound absorbing member 3 is fixed to the installation surface 24 by a plurality of strip-shaped frames 9 as fixing members. In this example, the frames 9 are arranged at intervals in the depth direction Y of the sound absorbing member 3.

Each frame 9 is connected to a pair of connecting portions 91 connected to the installation surface 24 on both sides of the sound absorbing member 3 in the width direction X, and a band-shaped pressing portion 92 for pressing the sound absorbing member 3 toward the installation surface 24. It has a pair of connecting portions 93 that connect each of the portions 91 to the pressing portion 92.

Each connecting portion 93 is arranged outside the side surface of the sound absorbing member 3. One end of the holding portion 92 is connected to one connecting portion 91 via one connecting portion 93. The other end of the holding portion 92 is connected to the other connecting portion 91 via the other connecting portion 93.

The pressing portion 92 is arranged along the width direction X of the sound absorbing member 3. Further, the pressing portion 92 presses the sound absorbing member 3 toward the installation surface 24 at a pressing position away from each of the fine holes 61. In this example, the pressing position of the pressing portion 92 is set on the virtual center line 71a where the distances from each of the two adjacent microholes 61 in the depth direction Y are equal. As a result, in this example, the distance from the center of each microhole 61 to the pressing position of the pressing portion 92 is larger than the inner diameter of each microhole 61.

Each frame 9 has the perforated plate 6 and the first surface 51 recessed in the installation surface 24 by pressing the sound absorbing member 3 at the pressing position by the pressing portion 92. In the porous member 5, the first surface 51 is recessed and elastically deformed to generate an elastic restoring force toward the perforated plate 6. When the perforated plate 6 receives the elastic restoring force of the porous member 5, tension is generated in the perforated plate 6.

Each frame 9 is made of a material that does not bend easily. As a result, tension can be generated in the perforated plate 6 at the pressing position over the entire pressing portion 92. As a material constituting each frame 9, metal, resin, or the like is used. Examples of the metal used as the material of each frame 9 include aluminum and stainless steel. Other configurations are the same as those in the first embodiment.

The height of the frame 9 is determined by the dimensions of the connecting portion 93 from the connecting portion 91 to the holding portion 92. The height of the frame 9 is set lower than the thickness direction of the sound absorbing member 3 when it is not fixed to the installation surface 24. When fixing the sound absorbing member 3 to the installation surface 24, the sound absorbing member 3 is fitted between the pair of connecting portions 93 and the frame 9 is pushed toward the installation surface 24. When the frame 9 is pushed toward the installation surface 24, the porous member 5 is elastically deformed while the perforated plate 6 and the first surface 51 are recessed toward the installation surface 24 by the pressing portion 92. After that, the sound absorbing member 3 is fixed to the installation surface 24 by connecting each connection portion 91 to the installation surface 24.

In such a sound absorbing device 1, the perforated plate 6 and the first surface 51 are recessed toward the installation surface 24 by the band-shaped pressing portion 92. Therefore, the range in which the perforated plate 6 and the first surface 51 are recessed can be expanded as compared with the pin 4. As a result, the range in which tension is generated in the perforated plate 6 can be expanded, and the range in which the perforated plate 6 is brought into close contact with the porous member 5 can be expanded. Therefore, the sound absorbing coefficient α of the sound absorbing member 3 can be further reliably improved, and the sound absorbing performance of the sound absorbing device 1 can be further reliably improved.

In the third embodiment, the band-shaped pressing portion 92 is arranged on the virtual center line 71a. However, the pressing position of the band-shaped pressing portion 92 is not limited to the position on the virtual center line 71a as long as it is a position avoiding each microhole 61.

Further, in the third embodiment, the sound absorbing member 3 according to the first embodiment is fixed to the installation surface 24 by the frame 9. However, the sound absorbing member 3 according to the second embodiment using the adhesive layer 8 may be fixed to the installation surface 24 by the frame 9.

Embodiment 4.
FIG. 20 is a perspective view showing a sound absorbing device according to a fourth embodiment of the present invention. The sound absorbing member 3 is fixed to the installation surface 24 by a cover 10 as a fixing member that covers the sound absorbing member 3.

The cover 10 has a pair of connecting portions 101 connected to the installation surface 24 on both sides of the sound absorbing member 3 in the depth direction Y, and a pair of plate-shaped pressing portions 102 that press the sound absorbing member 3 toward the installation surface 24. It has a pair of connecting portions 103 that connect each of the portions 101 to the pressing portion 102.

Each connecting portion 103 is arranged outside the side surface of the sound absorbing member 3. One end of the pressing portion 102 is connected to one connecting portion 101 via one connecting portion 103. The other end of the pressing portion 102 is connected to the other connecting portion 101 via the other connecting portion 103.

An opening 104 is formed in the pressing portion 102. The pressing portion 102 is arranged at the pressing position in a state where the plurality of micropores 61 are exposed through the opening 104. As a result, the frame-shaped range surrounding the periphery of the plurality of micropores 61 is the pressing position of the pressing portion 102. The pressing portion 102 presses the sound absorbing member 3 toward the installation surface 24 at a pressing position away from each of the fine holes 61. In this example, the distance from the center of each microhole 61 to the pressing position of the pressing portion 102, that is, the distance from the center of each microhole 61 to the inner peripheral portion of the opening 104 is larger than the inner diameter of each microhole 61. It has become.

The cover 10 has the perforated plate 6 and the first surface 51 recessed toward the installation surface 24 by pressing the sound absorbing member 3 at the pressing position by the pressing portion 102. In the porous member 5, the first surface 51 is recessed and elastically deformed to generate an elastic restoring force toward the perforated plate 6. When the perforated plate 6 receives the elastic restoring force of the porous member 5, tension is generated in the perforated plate 6. The material constituting the cover 10 is the same as the material constituting the frame 9 of the second embodiment. Other configurations are the same as those in the first embodiment.

The height of the cover 10 is determined by the dimensions of the connecting portion 103 from the connecting portion 101 to the holding portion 102. The height of the cover 10 is set lower than the thickness direction of the sound absorbing member 3 when it is not fixed to the installation surface 24. When fixing the sound absorbing member 3 to the installation surface 24, the sound absorbing member 3 is fitted between the pair of connecting portions 93 and the cover 10 is pushed toward the installation surface 24. At this time, the plurality of micropores 61 are exposed through the opening 104. When the cover 10 is pushed toward the installation surface 24, the porous member 5 is elastically deformed while the perforated plate 6 and the first surface 51 are recessed toward the installation surface 24 by the pressing portion 102. After that, the sound absorbing member 3 is fixed to the installation surface 24 by connecting each connection portion 101 to the installation surface 24.

Such a sound absorbing device 1 has a plate-shaped pressing portion 102 having an opening 104 formed therein. Further, the pressing portion 102 is arranged at the pressing position in a state where the plurality of micropores 61 are exposed through the opening 104. Therefore, the range in which the perforated plate 6 and the first surface 51 are recessed can be further expanded. As a result, the range in which tension is generated in the perforated plate 6 can be expanded, and the range in which the perforated plate 6 is brought into close contact with the porous member 5 can be expanded. Therefore, the sound absorbing coefficient α of the sound absorbing member 3 can be further reliably improved, and the sound absorbing performance of the sound absorbing device 1 can be further reliably improved. Further, since the range in which the sound absorbing member 3 is pressed can be expanded by the pressing portion 102, the sound absorbing member 3 can be easily and more reliably fixed to the installation surface 24 even when the aspect ratio of the sound absorbing member 3 is large. Can be done.

In the fourth embodiment, the sound absorbing member 3 according to the first embodiment is fixed to the installation surface 24 by the cover 10. However, the sound absorbing member 3 according to the second embodiment using the adhesive layer 8 may be fixed to the installation surface 24 by the cover 10.

1 Sound absorbing device, 3 Sound absorbing member, 4 Pin (fixing member), 5 Porous member, 6 Perforated plate (membrane-like body), 7a Virtual center line, 8 Adhesive layer, 9 Frame (fixing member), 10 Cover (fixing member) ), 24 Installation surface, 41 Penetration part, 43 Holding part, 51 First surface, 52 Second surface, 61 Microhole (through hole), 62 Protrusion part, 71a 1st virtual center line, 72a 2nd virtual center line, 81 adhesive part, 92 holding part, 102 holding part, 104 opening.

Claims

The sound absorbing member having a porous member on which the first surface and the second surface are formed and a film-like body overlapping the first surface and the second surface overlapping the installation surface, and the sound absorbing member are described. Equipped with a fixing member to be fixed to the installation surface
A plurality of through holes are formed in the film-like body, and the film-like body has a plurality of through holes.
The distance between each of the plurality of through holes is larger than the inner diameter of each of the through holes.
The fixing member is a sound absorbing device that fixes the sound absorbing member to the installation surface by recessing the film-like body and the first surface toward the installation surface at a holding position away from each of the plurality of through holes.
The sound absorbing device according to claim 1, wherein the distance from the center of each through hole to the holding position is larger than the inner diameter of each through hole.
The sound absorbing device according to claim 1 or 2, wherein the fixing member is a pin penetrating the sound absorbing member.
With a plurality of the fixing members
Each of the fixing members is a pin having a penetrating portion penetrating the sound absorbing member and a pressing portion that projects laterally from the penetrating portion and presses the film-like body at the pressing position.
Claims 1 to 3 wherein the length of the holding portion of each of the two adjacent pins is longer than 1/2 of the distance between the penetrating portions of the two pins. The sound absorbing device according to any one item.
The sound absorbing device according to claim 1 or 2, wherein the fixing member has a band-shaped pressing portion arranged at the pressing position.
The sound absorbing device according to any one of claims 1 to 5, wherein the holding position is on a virtual center line in which the distances from the centers of the two adjacent through holes are equal.
The fixing member has a holding portion having an opening formed therein.
The sound absorbing device according to claim 1 or 2, wherein the holding portion is arranged at the holding position with the plurality of through holes exposed through the opening.
A claim that includes an adhesive layer that is interposed between the film-like body and the first surface while avoiding the positions of the plurality of through holes, and adheres the film-like body to the first surface. The sound absorbing device according to any one of claims 1 to 7.
The adhesive layer has a plurality of adhesive portions and has a plurality of adhesive portions.
The sound absorbing device according to claim 8, wherein the plurality of adhesive portions are located at positions sandwiching the through holes when the sound absorbing member is viewed along the direction in which the film-like body overlaps the porous member. ..
The sound absorption according to any one of claims 1 to 9, wherein a protrusion protruding from the film-like body is provided on the peripheral edge of each through hole on the side opposite to the porous member side. apparatus.