Sound absorption structure

Abstract

To provide a sound absorption structure that is easier to be formed compared to a configuration that includes a step in a partition member.SOLUTION: A sound absorption structure 20 is mounted on a mounting surface 10A. On a surface of the mounting surface 10A, the structure comprises: a partition member 22 that partitions an area C having a constant width in a normal direction of the mounting surface 10A; a plurality of partition plates 24 that are mounted on the partition member 22 at intervals in the normal direction and protrude toward the area C parallel to the mounting surface 10A; and a hole C2 that is formed between free ends 24A of the partition plates 24, has a constant diameter in the normal direction and communicates with a space C1 between the partition plates 24.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a sound absorbing structure. [Background technology]

[0002] The following Patent Document 1 describes a silencer configuration in which a stepped hole is formed in a plate-like member and a partition plate made of a thin plate material is attached to the stepped surface, thereby providing a plurality of hollow chambers arranged in order of volume size. In this silencer, the volumes of the wind tunnel chambers between the partition plates are configured to be different, thereby achieving a noise reduction effect. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-333686 Summary of the Invention [Problem to be solved by the invention]

[0004] In the silencer disclosed in Patent Document 1, it is necessary to change the volume for each thick hollow chamber, which makes the processing of the partition members that form the outer edges of the hollow chambers complicated.

[0005] In consideration of the above, the present invention aims to provide a sound-absorbing structure that is easier to form than a structure in which a step is provided in a partition member. [Means for solving the problem]

[0006] The sound-absorbing structure of claim 1 comprises a partition member that is attached to a mounting surface and that partitions an area on the surface of the mounting surface, the area having a constant width in the normal direction of the mounting surface; partition plates that are attached to the partition member at intervals in the normal direction and extend into the area parallel to the mounting surface; and holes that are formed between the free ends of the partition plates and have a constant diameter in the normal direction, connecting to the space between the partition plates.

[0007] In the sound-absorbing structure of claim 1, holes are formed between the free ends of the partition plates inside the area partitioned by the partitioning members. The elastic modulus of the air in these holes is smaller than when there is no space between the partition plates due to the action of the air in the space between the partition plates. This lowers the resonant frequency, making it easier to absorb low-frequency sounds. Furthermore, it is possible to absorb lower-frequency sounds than when the space between the partition plates is used as a resonator.

[0008] In addition, sound waves that enter the holes are attenuated by the viscous and thermal effects that occur on the surface of the partition plate, so the larger surface area also increases the dissipation of sound energy compared to when there are only holes, thereby improving the sound absorption effect.

[0009] In addition, since there is no need to make the volumes of the spaces inside the partition plate different in order to achieve a sound-absorbing effect, it is easier to form a sound-absorbing structure compared to a configuration in which steps are provided in the partition members to make the volumes different.

[0010] The sound-absorbing structure of claim 2 comprises a partition member attached to a mounting surface and defining an area on the surface of the mounting surface, the area having a constant width in the normal direction of the mounting surface; partition plates attached to the partition member at intervals in the normal direction and extending into the area parallel to the mounting surface; and holes formed between the free ends of the partition plates and having a diameter that varies in the normal direction, the holes communicating with the spaces between the partition plates.

[0011] In the sound-absorbing structure of claim 2, a hole is formed between the free ends of the partition plates inside the area defined by the partitioning member. The diameter of this hole varies in the normal direction to the mounting surface. By varying the hole diameter, the acoustic impedance can be changed to adjust the state of the reflected waves, thereby adjusting the sound absorption effect.

[0012] Furthermore, the width of the area defined by the partition member is constant in the direction normal to the mounting surface, which makes it easier to form a sound-absorbing structure compared to a configuration in which the partition member has steps.

[0013] A sound absorbing structure according to a third aspect of the present invention is the sound absorbing structure according to the second aspect, wherein the hole has a diameter that gradually decreases toward the mounting surface in the normal direction.

[0014] In the sound-absorbing structure of claim 3, the diameter of the hole formed between the free ends of the partition plates is shaped like a mortar, gradually decreasing toward the mounting surface. The smaller the diameter of the part through which sound passes, the greater the acoustic impedance. However, because the hole diameter gradually decreases, the acoustic impedance of sound waves entering the hole gradually increases. By providing continuity in impedance in this way, reflected waves are less likely to occur. This achieves a sound-absorbing effect.

[0015] In addition, by providing continuity in impedance with the mounting surface, it is possible to prevent reflected waves from occurring at the mounting surface. Furthermore, since the number and thickness of the partition plates are finite, it is easy to absorb high-frequency sounds with short wavelengths.

[0016] The sound absorbing structure of claim 4 is the sound absorbing structure of claim 1, further comprising a variable mechanism that varies the width of the holes formed by the partition plates.

[0017] The sound absorbing structure of claim 4 is provided with a variable mechanism that changes the width of the holes. This makes it possible to obtain both the effect of a sound absorbing structure with fixed hole widths and the effect of a sound absorbing structure with variable hole widths. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a sound absorbing structure that is easier to form than a structure in which a step is provided in a partition member. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1A is a schematic diagram showing a sound absorbing structure according to a first embodiment of the present invention as viewed from the front, and FIG. 1B is a cross-sectional view taken along line BB in FIG. [Figure 2] 1 is a partially enlarged cross-sectional view of a sound absorbing structure according to a first embodiment of the present invention. [Figure 3]1A is a cross-sectional view showing a sound absorbing structure according to a comparative example, and FIG. 1B is a cross-sectional view showing a sound absorbing structure according to another comparative example. [Figure 4] FIG. 1A is a schematic diagram showing a sound absorbing structure according to a modified example of the first embodiment as viewed from the front, and FIG. 1B is a schematic diagram showing a sound absorbing structure according to another modified example as viewed from the front. [Figure 5] 1A is a cross-sectional view showing a modified example of a partition member in the sound absorbing structure of the first embodiment, and FIG. 1B is a cross-sectional view showing a state in which a partition plate is attached to the modified partition member. [Figure 6] 1A is a cross-sectional view showing the state in which the partition members and partition plates are unitized in the sound-absorbing structure of the first embodiment, and FIG. 1B is a cross-sectional view showing the state in which the unitized partition members and partition plates are arranged adjacent to each other to form a sound-absorbing structure. [Figure 7] FIG. 4 is a partially enlarged cross-sectional view of a sound absorbing structure according to a second embodiment of the present invention. [Figure 8] 1A is a graph showing an example of the sound absorbing effect of the sound absorbing structure according to the first embodiment, and FIG. 1B is a graph showing an example of the sound absorbing effect of the sound absorbing structure according to the second embodiment. [Figure 9] (A) is a cross-sectional view showing a modified example in which the diameter of the hole in the sound-absorbing structure of the second embodiment changes in a curved line toward the mounting surface; (B) is a cross-sectional view showing a modified example in which the diameter of the hole gradually increases toward the mounting surface; (C) is a cross-sectional view showing a modified example in which the diameter of the hole has portions where it gradually decreases and portions where it gradually increases toward the mounting surface; and (D) is a cross-sectional view showing a modified example in which the diameter of the hole changes so that it has a step. [Figure 10] (A) is a front view showing an example in which a partition plate is formed by an aperture plate that rotates relative to a cylindrical partition member, and (B) is a front view showing an example in which a partition plate is formed by an aperture plate that slides relative to each cylindrical partition member. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, a sound-absorbing structure according to an embodiment of the present invention will be described with reference to the drawings. Components indicated by the same reference numerals in the various drawings are the same components. However, unless otherwise specified in the specification, each component is not limited to one, and multiple components may be present.

[0021] Furthermore, descriptions of overlapping configurations and symbols in each drawing may be omitted. Note that the present disclosure is not limited to the following embodiments, and may be implemented by making appropriate modifications, such as omitting configurations, replacing them with different configurations, or combining one embodiment with various modified examples, within the scope of the purpose of the present disclosure.

[0022] In each drawing, the directions indicated by arrows X and Y are directions along the horizontal plane and are perpendicular to each other. The direction indicated by arrow Z is a direction along the vertical direction (up and down). In each drawing, the directions indicated by arrows X, Y, and Z are assumed to be consistent with each other.

[0023] <Sound-absorbing structure> The sound-absorbing structure according to the embodiment of the present invention is an acoustic member that is attached to, for example, a wall or ceiling surface of a building and absorbs sound generated in an indoor space or the like.

[0024] [First embodiment] As shown in FIGS. 1(A) and 1(B), the sound absorbing structure 20 of the first embodiment includes a partition member 22, a partition plate 24, and a surface material 26.

[0025] (compartment member) The partition member 22 is a cylindrical plate member attached to the mounting surface 10A, such as the wall or ceiling surface. The mounting surface 10A is a surface extending along the X and Y directions. As shown in Fig. 2, the partition member 22 is attached so that its cylindrical axis direction is aligned with the normal direction (Z direction and the direction along the dashed-dotted line CL) of the mounting surface 10A.

[0026] As a result, the partitioning member 22 partitions an area C on the surface of the mounting surface 10A, the area C having a constant width Rc in the normal direction of the mounting surface 10A. The width Rc is not particularly limited, but is preferably about 10 to 500 mm.

[0027] (Divider) The partition plate 24 is an annular plate material fixed to the inner peripheral surface of the dividing member 22 and extending parallel to the mounting surface 10A toward the region C. A plurality of partition plates 24 are provided in the normal direction of the mounting surface 10A and are arranged in a comb shape in cross section. As a result, the partition plates 24 divide the region C into a plurality of spaces C1 in the normal direction of the mounting surface 10A. In the following description, these spaces C1 may be referred to as cavities C1.

[0028] The overhang width of the partition plates 24 is constant among the multiple partition plates 24 and is smaller than half the width Rc of the region C (i.e., Rc / 2; in other words, the radius of the circular region C). As a result, holes C2 with a constant diameter Rp in the normal direction of the mounting surface 10A are formed between the free ends 24A of the partition plates 24. These holes C2 are connected to the respective cavities C1 between the partition plates 24.

[0029] The configuration of the partition plates 24 can be restated as follows. Each partition plate 24 is a circular plate that divides the cylindrical partition member 22 in the axial direction, and has a through-hole formed in its center. The through-holes in each partition plate 24 have a uniform diameter Rp, and are located at the same center as viewed from the axial direction of the partition member 22. As a result, a hole C2 with a diameter Rp is formed in the center of the partition member 22. Furthermore, cavities C1, which are spaces divided by the partition plates 24, are formed to be connected to the hole C2.

[0030] The number of partition plates 24 is not particularly limited, but it is preferable to provide three or more. The thickness Hp of the partition plates 24 is preferably about 0.1 to 5 mm. The thickness Hc of the cavity C1 is preferably about 0.1 to 50 mm. The diameter Rp of the hole C2 is preferably about 0.1 to less than 500 mm.

[0031] 1(A) and 1(B), a plurality of partition members 22 to which partition plates 24 are fixed are arranged in the in-plane direction of the mounting surface 10A. In this example, a plurality of partition members 22 to which partition plates 24 are fixed are arranged side by side in the X direction and the Y direction.

[0032] (Surface material) The surface material 26 is a plate material that is disposed parallel to the mounting surface 10A and covers the multiple partition members 22. Multiple holes 26A with a diameter Rp are formed in the surface material 26. As shown in FIG. 2, the centers of the holes 26A and the hole C2 are aligned.

[0033] (effect) According to the sound absorbing structure 20 of the first embodiment, inside the area C defined by the partition member 22, a hole C2 is formed between the free ends 24A of the partition plates 24.

[0034] The elastic modulus of the air in the holes C2 is smaller due to the action of the air in the cavities C1 between the partition plates 24 than when there are no cavities C1 between the partition plates 24.

[0035] Note that "when there is no cavity C1" refers to a case where there is only a hole C2 without a cavity C1, as shown in the comparative example of FIG. 3(A).

[0036] This results in a lower resonance frequency than when there is no cavity C1, making it easier to absorb low-frequency sounds, as shown in Fig. 8(A) for example. Also, it is possible to absorb lower-frequency sounds than when the cavity C1 between the partition plates 24 is used as a resonator.

[0037] Furthermore, as shown in Figure 2, sound waves incident on hole C2 are attenuated by the viscosity and thermal effects that occur on the surface of partition plate 24, so the larger surface area results in greater dissipation of sound energy compared to the case where only hole C2 is present (see Figure 3(A)), thereby improving the sound absorption effect.

[0038] Furthermore, since it is not necessary to make the volumes of the cavities C1 inside the partition plate 24 different in order to obtain a sound-absorbing effect, it is easier to form a sound-absorbing structure compared to a configuration in which steps are provided in the partition member to make the volumes different, such as each cavity C10 shown in the comparative example of Figure 3(B).

[0039] (Variation) In the above embodiment, the partition member 22 is formed in a cylindrical shape, and the partition plate 24 is an annular plate material fixed to the inner peripheral surface of the partition member 22. In this way, a round-hole type sound-absorbing structure 20 is formed, but the embodiment of the present invention is not limited to this.

[0040] For example, the partitioning member may be formed in a rectangular cylindrical shape like partitioning member 22M shown in Fig. 4(A), and the partition plate may be a frame-shaped plate like partition plate 24M, thereby forming a square-hole sound absorbing structure 20.

[0041] Also, for example, the partitioning member may be formed as a pair of parallel plates like partitioning member 22N shown in Fig. 4(B), and the partition plate may be a long plate like partition plate 24N, thereby forming a slit-type sound absorbing structure 20.

[0042] Furthermore, in the above embodiment, the partition member 22 is formed of a plate material that is aligned in the normal direction of the attachment surface 10A, but the embodiment of the present invention is not limited to this.

[0043] For example, as in the case of partition member 28 shown in Fig. 5(A), the partition member may be formed of a plate material that extends along the in-plane direction of mounting surface 10A. In this case, a through hole that forms area C is formed in partition member 28, and partition plate 24 is attached to the hole wall of this through hole as shown in Fig. 5(B).

[0044] In the above embodiment, the partition members 22 to which the partition plates 24 are fixed are arranged spaced apart from each other, but the present invention is not limited to this. For example, as shown in Fig. 6(A), the partition members 22 to which the partition plates 24 are fixed may be formed as a unit, and these may be arranged side by side so as to be in contact with each other, as shown in Fig. 6(B). In this embodiment, the surface member 26 can be omitted.

[0045] In the above embodiment, the cavity C1 and the hole C2 are filled with only air without any filling material, but the present invention is not limited to this. For example, the cavity C1 and the hole C2 may be filled with a porous sound-absorbing material such as glass wool.

[0046] [Second embodiment] In the second embodiment, the description of the same configuration as in the first embodiment will be omitted, and only the configuration and effects different from those in the first embodiment will be described. Various modifications of the first embodiment can also be applied to the second embodiment.

[0047] First, as shown in Fig. 2, in the sound-absorbing structure 20 of the first embodiment, the diameter Rp of the holes C2 between the free ends 24A of the partition plates 24 is constant in the normal direction to the mounting surface 10A. On the other hand, in the sound-absorbing structure 30 of the second embodiment, as shown in Fig. 7, the diameters Rp(n), Rp(n+1), ... (hereinafter referred to as "diameter Rp") of the holes C2 between the free ends 24A of the partition plates 24 vary in the normal direction to the mounting surface 10A.

[0048] Specifically, the diameter Rp of the hole C2 gradually decreases toward the mounting surface 10A in the normal direction of the mounting surface 10A. Moreover, the diameter Rp of the hole C2 gradually decreases so that the line K1 connecting the free ends 24A of the partition plates 24 becomes straight in a cross-sectional view of the sound-absorbing structure 30. Furthermore, the diameter Rp of the hole C2 gradually decreases so that its value becomes zero at the mounting surface 10A.

[0049] (effect) According to the sound-absorbing structure 30 of the second embodiment, a hole C2 is formed between the free ends 24A of the partition plates 24 inside the area C defined by the partition member 22. The diameter Rp of this hole C2 varies in the normal direction of the mounting surface 10A. By varying the hole diameter, the acoustic impedance can be changed, thereby adjusting the state of the reflected waves. This allows the sound-absorbing effect to be adjusted.

[0050] The hole C2 formed between the free ends 24A of the partition plates 24 has a mortar shape with a diameter Rp that gradually decreases toward the mounting surface 10A.

[0051] Acoustic impedance increases as the diameter of the part through which sound passes becomes smaller, but because the diameter Rp of hole C2 gradually decreases, the acoustic impedance of sound waves entering hole C2 gradually increases. By providing continuity in impedance in this way, reflected waves are less likely to occur, resulting in a sound absorption effect.

[0052] Furthermore, hole C2 gradually tapers so that the impedance becomes zero at mounting surface 10A. By providing continuity in impedance with mounting surface 10A, where the impedance becomes infinite, it is possible to prevent reflected waves from occurring at mounting surface 10A.

[0053] Furthermore, since the number and thickness of the partition plates 24 are finite, they are more effective in absorbing high-frequency sounds with short wavelengths. For example, as shown in Fig. 8(B), high-frequency sounds can be more easily absorbed.

[0054] Moreover, the width of the region C defined by the partitioning member is constant in the normal direction of the mounting surface 10A, which makes it easier to form a sound-absorbing structure compared to forming a region with a variable width by providing a step in the partitioning member, such as region C100 shown in the comparative example of Fig. 3(B).

[0055] (Variation) In the above embodiment, the hole C2 has a mortar shape in which the diameter Rp gradually decreases linearly toward the mounting surface 10A, but the embodiment of the present invention is not limited to this.

[0056] That is, when the diameter Rp changes in the normal direction of the mounting surface 10A, the shape is not particularly limited.

[0057] For example, as shown in Fig. 9(A), the diameter Rp of the hole C2 may gradually decrease in a curved manner (curved) toward the mounting surface 10A. Alternatively, as shown in Fig. 9(B), the diameter Rp of the hole C2 may gradually increase toward the mounting surface 10A (this may be linear or curved). Furthermore, as shown in Fig. 9(C), the diameter Rp of the hole C2 may have portions where it gradually decreases and portions where it gradually increases toward the mounting surface 10A (this may be linear or curved).

[0058] Furthermore, the diameter Rp of the hole C2 does not have to "gradually decrease (increase)," i.e., not change continuously (gradually). For example, as shown in FIG. 9(D), the diameter may change to form a step. Furthermore, the diameter of the hole C2 may have both a portion that changes along the normal direction of the mounting surface 10A and a portion that does not change.

[0059] In these embodiments, desired sound absorption characteristics can be obtained depending on the shape of the hole C2.

[0060] (variable mechanism) Each aspect of the diameter Rp of the hole C2 shown in the sound absorbing structure 20 or 30 described above may be a variable sound absorbing structure using a variable mechanism that changes the width of the hole C2 formed by the partition plate 24.

[0061] 10(A), for example, an adjustable mechanism applicable to a cylindrical partition member 22 may be configured such that the partition plate 24 is formed of a plurality of diaphragm plates 24F, which are rotating bodies. The diaphragm plates 24F can adjust the diameter Rp of the holes C2 by rotating.

[0062] 10(B), for example, an adjustable mechanism applicable to a rectangular cylindrical partition member 22 may be configured such that the partition plate 24 is formed of a plurality of diaphragm plates 24E, which are sliding members. The diaphragm plates 24E are slidably fixed to the partition member 22, and the diameter Rp of the hole C2 can be adjusted by sliding.

[0063] The variable mechanism is connected to a power supply and a control device (not shown), and can be used via input operations to the control device.

[0064] By using such a variable mechanism, it is possible to obtain the effects of the sound absorbing structure 20 of the first embodiment and the sound absorbing structure 30 of the second embodiment, and also to adjust the shape of the hole C2 to any desired shape to obtain the desired effect. As such, the present invention can be embodied in various forms. [Explanation of symbols]

[0065] 20 Sound-absorbing structure 22 Partition members 22M partition member 22N Partition member 24 Partition 24A free end 24E Diaphragm plate (partition plate) 24F Diaphragm plate (partition plate) 28 Partition members 30 Sound-absorbing structure C2 hole

Claims

1. a partition member attached to the mounting surface and partitioning an area having a constant width in a normal direction of the mounting surface on the surface of the mounting surface; a plurality of partition plates attached to the partition member at intervals in the normal direction and extending into the region parallel to the attachment surface; a hole formed between the free ends of the partition plates, the hole having a constant diameter in the normal direction and communicating with the space between the partition plates; Sound-absorbing structure with

2. a partition member attached to the mounting surface and partitioning an area having a constant width in a normal direction of the mounting surface on the surface of the mounting surface; a plurality of partition plates attached to the partition member at intervals in the normal direction and extending into the region parallel to the attachment surface; a hole formed between the free ends of the partition plates, the hole having a diameter that changes in the normal direction and that communicates with the space between the partition plates; Sound-absorbing structure with

3. The hole has a diameter that gradually decreases toward the mounting surface in the normal direction. The sound absorbing structure according to claim 2.

4. The sound absorbing structure according to claim 1 , further comprising a variable mechanism for varying the width of the holes formed by the partition plates.

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