Sound absorption structure body

Abstract

To provide a sound absorption structure body that achieves sound absorption across a wide frequency range while suppressing weight increase.SOLUTION: A sound absorption structure body 1 comprises a plate structure 2 that is a plate-like structure facing both a sound source side and a fixed side, and a housing 3 that forms a space capable of accommodating the plate structure 2. The plate structure 2 includes a membrane structure body 4, which is a membrane-like member facing both the sound source side and the fixed side, and a structural membrane portion 5 facing the membrane structure body 4 toward the sound source side. The structural membrane portion 5 has protrusions 51 that form a space 52 protruding toward the sound source side.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] High sound insulation is required in some spaces such as offices, conference rooms, homes, factories, etc. For this reason, sound-absorbing structures with sound-absorbing properties have conventionally been provided in such spaces on partitions such as walls, ceilings, and floors (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-96826 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, the sound-absorbing structure described in Patent Document 1 exhibits sound-absorbing properties in the low-frequency range, while conventional sound-absorbing structures exhibit sound-absorbing properties in specific frequency ranges, such as the low-frequency range, the mid-frequency range, or the high-frequency range. On the other hand, when sound-absorbing properties are to be exhibited in a wide frequency range, the sound-absorbing structure becomes large and heavy. For this reason, there is a demand for a configuration that exhibits sound-absorbing properties in a wide frequency range while suppressing the increase in weight of conventional sound-absorbing structures.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a sound-absorbing structure that exhibits sound-absorbing properties over a wide frequency range while suppressing an increase in weight. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the sound-absorbing structure of the present invention comprises a plate structure which is a plate-shaped structure facing one side and the other side opposite the one side, and a housing which is a member which forms a space capable of accommodating the plate structure, wherein the plate structure has a membrane structure which is a membrane-shaped member which faces the one side and the other side, and a structural membrane portion which faces the membrane structure toward the one side, and the structural membrane portion has a plurality of protrusions which protrude toward the one side and form a space.

[0007] In one aspect of the sound-absorbing structure of the present invention, the membrane structure has a membrane body which is a membrane-shaped member and an elastic membrane portion which is a membrane-shaped member having elasticity, and the membrane body has a pair of back-to-back surfaces which face the one side and the other side, respectively.

[0008] In the sound absorbing structure according to one aspect of the present invention, the elastic membrane portion has a plurality of through holes.

[0009] In the sound absorbing structure according to one aspect of the present invention, the film body is a member that suppresses air permeation.

[0010] In the sound absorbing structure according to one aspect of the present invention, the film body has a base film portion which is a film-like member, and an air-blocking film portion which is a film-like member for blocking air.

[0011] In the sound absorbing structure according to one aspect of the present invention, the air blocking membrane is made of resin.

[0012] In the sound absorbing structure according to one aspect of the present invention, the base film portion and the air blocking film portion are bonded to each other.

[0013] In the sound absorbing structure according to one aspect of the present invention, the structural film portion is a Helmholtz resonator.

[0014] In the sound absorbing structure according to one aspect of the present invention, the structural membrane portion is formed from a foam.

[0015] In a sound-absorbing structure according to one aspect of the present invention, the plate structure further includes a beam body between the membrane structure and the structural membrane portion, and the beam body supports the structural membrane portion relative to the membrane structure.

[0016] In a sound absorbing structure according to one aspect of the present invention, the beam defines a space that accommodates the plurality of protrusions of the structural membrane.

[0017] In the sound absorbing structure according to one aspect of the present invention, the beams are lattice-shaped.

[0018] In the sound absorbing structure according to one aspect of the present invention, the beams are formed from a foam.

[0019] In the sound absorbing structure according to one aspect of the present invention, the housing is formed from a foam. [Effects of the Invention]

[0020] The sound absorbing structure according to the present invention can absorb sound over a wide frequency range while suppressing an increase in weight. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a perspective view showing a schematic configuration of a sound absorbing structure according to an embodiment of the present invention. [Figure 2] 1 is an exploded perspective view of a sound absorbing structure according to an embodiment of the present invention. [Figure 3] 1 is a view showing the internal structure of a sound absorbing structure according to an embodiment of the present invention, with a partial see-through view. [Figure 4] 1 is a perspective view of a membrane structure of a plate structure in a sound absorbing structure according to an embodiment of the present invention. FIG. [Figure 5] 1 is a perspective view of a structural membrane portion of a sound absorbing structure according to an embodiment of the present invention, viewed from the fixed side. [Figure 6] 1 is a cross-sectional view of a sound absorbing structure according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that in the drawings, not all of the components are labeled with reference numerals, and some of the components may be omitted.

[0023] FIG. 1 is a perspective view showing the schematic configuration of a sound-absorbing structure 1 according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view of the sound-absorbing structure 1. FIG. 3 is a view showing the internal structure of the sound-absorbing structure 1, with part of the sound-absorbing structure 1 seen through. As shown in FIGS. 1 to 3, the sound-absorbing structure 1 includes a plate structure 2, which is a plate-like structure facing one side and the other side opposite the one side, and a housing 3, which is a member forming a space capable of accommodating the plate structure 2. The plate structure 2 includes a membrane structure 4, which is a film-like member facing one side and the other side, and a structural membrane portion 5 facing the membrane structure 4 from one side. The structural membrane portion 5 has a plurality of protrusions 51 that protrude in one direction and form spaces 52. The configuration of the sound-absorbing structure 1 will now be described in detail.

[0024] 1 to 3, for convenience of explanation, one side of the plate structure 2 facing (the direction of arrow a) is referred to as the sound source direction, and the other side of the plate structure 2 facing (the direction of arrow b) is referred to as the fixed direction. Also, the side facing the sound source direction is referred to as the sound source side, and the side facing the fixed direction is referred to as the fixed side.

[0025] As shown in Figures 1 and 3, the sound-absorbing structure 1 has a rectangular or substantially rectangular box-like shape when viewed from the front. Note that the front view means viewing an object in a fixed direction. Also, as shown in Figures 2 and 3, multiple membrane-like members are housed inside the sound-absorbing structure 1. The shape of the sound-absorbing structure 1 is not limited to this, and other shapes are also possible.

[0026] Fig. 4 is a perspective view of the membrane structure 4 of the plate structure 2. Fig. 4 shows the membrane structure 4 as seen from the fixed side. As shown in Figs. 2 and 4, the membrane structure 4 of the plate structure 2 has a membrane body 10 which is a membrane-like member and an elastic membrane portion 20 which is a membrane-like member having elasticity, and the membrane body 10 and the elastic membrane portion 20 are fixed to each other and formed integrally.

[0027] The membrane 10 is a vibrating membrane that vibrates in the sound source direction and the fixed direction. As shown in Figures 2 and 4, the membrane 10 is a thin membrane-like member and has a pair of opposite surfaces, a front surface 10a and a back surface 10b, that face the sound source direction and the fixed direction, respectively. The membrane 10 is a member that is impermeable to air or has low air permeability.

[0028] 1 to 4, the membrane body 10 has a base membrane portion 11, which is a membrane-like member, and an air-blocking membrane portion 12, which is a membrane-like member for blocking air. The base membrane portion 11 and the air-blocking membrane portion 12 are fixed to each other and integrated.

[0029] The base film portion 11 is a felt, or a felt sheet, having a predetermined shape in a front view and a predetermined thickness, as shown in Figures 2 and 4, for example. The shape of the base film portion 11 in a front view is, for example, rectangular or approximately rectangular. However, the shape of the base film portion 11 in a front view is not limited to this. Furthermore, the material of the base film portion 11 is not limited to a felt sheet. The material of the base film portion 11 may be other materials as long as they enable the base film portion 11 to vibrate, and the material of the base film portion 11 may be, for example, a foam sheet, cloth, or nonwoven fabric.

[0030] The air barrier film portion 12 is a member for blocking air in the film body 10. Specifically, it is a member that does not allow air to pass through or that is difficult for air to pass through. The air barrier film portion 12 is, for example, a plastic film. The shape of the air barrier film portion 12 in a front view corresponds to the shape of the base film portion 11 in a front view and is the same as or approximately the same as the shape of the base film portion 11 in a front view. Note that the material of the air barrier film portion 12 may be other materials. Also, the air barrier film portion 12 may be formed from a material that can close a space, such as an adhesive or glue. In this case, specifically, for example, the base film portion 11 has gaps such as meshes that allow air to pass through, like a felt sheet, and the air barrier film portion 12 is formed to close these gaps. Note that, for example, if the base film portion 11 is an air-impermeable material or a material that is difficult for air to pass through, the film body 10 may not have the air barrier film portion 12.

[0031] As shown in Figures 2 and 4, the base film portion 11 and the air barrier film portion 12 are fixed together and integrated, with the base film portion 11 facing the air barrier film portion 12 in the fixing direction and the air barrier film portion 12 facing the base film portion 11 in the sound source direction. For example, the base film portion 11 and the air barrier film portion 12 are bonded together and integrated. In this case, the air barrier film portion 12 is, for example, a plastic adhesive film, and an adhesive layer having adhesiveness is formed on the surface of the air barrier film portion 12 facing the sound source. In the film body 10, the base film portion 11 forms the front surface 10a, and the air barrier film portion 12 forms the back surface 10b. Furthermore, if the material of the air barrier film portion 12 is a material that can close a space, such as an adhesive or glue, the adhesive or glue is applied to the surface of the base film portion 11 in the form of a film to form the film-like air barrier film portion 12. The air barrier film portion 12 is not limited to being spread uniformly over the surface of the base film portion 11, but may be spread in a scattered manner over the surface of the base film portion 11.

[0032] As shown in FIGS. 2 to 4, the elastic membrane 20 has a plurality of through holes 21. For example, as shown in FIGS. 2 to 4, the elastic membrane 20 is a lattice-like member extending along a plane, and has a plurality of rows of through holes 21, each row having a plurality of through holes 21 arranged side by side. These rows are aligned. The plurality of through holes 21 are rectangular or approximately rectangular, as shown in FIGS. 3 and 4, for example. The elastic membrane 20 is made of, for example, resin. The elastic membrane 20 is configured to vibrate in the sound source direction and the fixed direction. Specifically, for example, the resin material of the elastic membrane 20 is a hard resin. Note that the material of the elastic membrane 20 is not limited to resin. For example, the material of the elastic membrane 20 may be wood, such as bamboo. The elastic membrane 20 may also be made by, for example, resin molding, or by crossing and fixing a plurality of thin rod-shaped or plate-shaped members.

[0033] As shown in Fig. 4, the membrane 10 and the elastic membrane portion 20 are fixed together with the elastic membrane portion 20 facing the back surface 10b of the membrane 10, thereby constituting the membrane structure 4. For example, the membrane 10 and the elastic membrane portion 20 are bonded together to form a single unit. As shown in Fig. 4, in the membrane structure 4, each through-hole 21 of the elastic membrane portion 20 is located on the back surface 10b of the membrane 10, and the opening of each through-hole 21 on the sound source side is closed by the back surface 10b of the membrane 10, while the opening of each through-hole 21 on the fixed side is open.

[0034] As described above, the membrane body 10 and the elastic membrane portion 20 are integrated to form a membrane-like member capable of membrane vibration toward the sound source side and the fixed side.

[0035] As described above, the structural membrane 5 has protrusions 51 that form spaces 52 that protrude toward multiple sound sources. The structural membrane 5 is formed, for example, from a foam material, specifically, foamed polypropylene. Note that the material of the structural membrane 5 is not limited to foamed polypropylene and may be other materials. Specifically, the structural membrane 5 is a Helmholtz resonator. A Helmholtz resonator is a resonator that utilizes Helmholtz resonance. The structural membrane 5 forms air chambers in the spaces 52 formed by each protrusion 51, and the air in the air chambers is vibrated by sound transmitted through the air chambers. When the frequency of the sound transmitted through the air chambers matches the natural frequency of the air chambers, resonance occurs, and the friction of the vibrating air reduces the sound energy.

[0036] FIG. 5 is a perspective view of the structured membrane unit 5 as viewed from the fixed side. As shown in FIGS. 2, 3, and 5, the structured membrane unit 5 has protrusions 51 of various sizes and heights, with spaces 52 of various sizes formed inside the multiple protrusions 51. Specifically, as shown in FIGS. 2, 3, and 5, the structured membrane unit 5 has a bottom 53 extending along a plane facing the sound source direction and the fixed direction, with multiple protrusions 51 protruding from the bottom 53 toward the sound source. The thickness of the bottom 53 is uniform or approximately uniform throughout, and the thickness of the multiple protrusions 51 is uniform or approximately uniform throughout. Furthermore, the thickness of the multiple protrusions 51 and the thickness of the bottom 53 are the same or approximately the same. As shown in FIGS. 2 and 3, each of the multiple protrusions 51 has a top plate portion 54, which is a plate-shaped portion facing the sound source, on the sound source side. Furthermore, a through-hole 55 is formed in each of the top panel portions 54 of the plurality of protrusions 51, penetrating the top panel portion 54. In each of the protrusions 51, the through-hole 55 connects the space 52 on the sound source side to the outside. Furthermore, as shown in Fig. 5 , the space 52 of each of the plurality of protrusions 51 is open to the fixed side, and an opening is formed in the bottom portion 53.

[0037] As shown in FIGS. 2 and 3 , the structural membrane 5 has, for example, a protrusion group 5a in which a plurality of protrusions 51 of various sizes and heights are arranged in a predetermined pattern. The sizes and heights of the protrusions 51 of the structural membrane 5 are adjusted, for example, so as to absorb high-frequency sounds. The structural membrane 5 is not limited to a structure in which the sizes and heights of the protrusions 51 are adjusted so as to absorb high-frequency sounds. The protrusions 51 in the protrusion group 5a may each have different sizes and heights, or the plurality of protrusions 51 may include one or more sets of protrusions 51 having the same size and height. The structural membrane 5 also has, for example, a plurality of protrusion groups 5a, which are arranged in an array. For example, as shown in FIGS. 2 and 3 , the structural membrane 5 has a plurality of rows in which the protrusion groups 5a are aligned, and the rows in which the protrusion groups 5a are aligned are arranged in parallel. In the illustrated example, for example, two rows are arranged in parallel, each row being formed by arranging four protrusion groups 5a in series.

[0038] As described above, the structural membrane 5 has a plurality of protrusions 51 of various sizes and heights, each of which has a predetermined natural frequency. Furthermore, the protrusion group 5a has a plurality of protrusions 51 each having a different natural frequency, arranged in a predetermined pattern, thereby providing a sound-absorbing effect for sounds within a predetermined frequency range. The combination of the plurality of protrusions 51 in the structural membrane 5 is not limited to that shown in the figure.

[0039] 2 to 4, the plate structure 2 further includes beams 6 between the membrane structure 4 and the structural membrane portion 5. The beams 6 are members that support the structural membrane portion 5 relative to the membrane structure 4. The beams 6 are formed, for example, from a foam material, specifically, for example, foamed polypropylene. Note that the material of the beams 6 is not limited to foamed polypropylene, and other materials may also be used.

[0040] As shown in FIG. 3, the beam 6 defines a space 6a that accommodates the multiple protrusions 51 of the structural membrane 5. As shown in FIGS. 2 and 3, for example, the beam 6 has a lattice shape and includes a frame 61 and wall portions 62 and 63 extending within the frame 61. The frame 61 is formed by a plate-like wall portion extending in an annular shape, and has a shape corresponding to the outer edge of the structural membrane 5. As shown in FIG. 3, for example, the frame 61 extends in a rectangular annular shape and is formed by a series of plate-like wall portions 61a, 61b, 61c, and 61d extending along four planes. The wall portions 62 and 63 are each a plate-like member extending along a plane, as shown in FIG. 3, for example. The wall portions 62 and 63 each extend crosswise within the space surrounded by the frame 61, dividing the space surrounded by the frame 61 into multiple spaces 6a.

[0041] The walls 62 and 63 divide the space surrounded by the frame 61 into multiple spaces 6a, for example, corresponding to the protrusion group 5a of the structural membrane 5. The beam 6 has one wall 62 and three walls 63, for example, as shown in Fig. 3 . The wall 62 extends between the walls 61b and 61d at the middle or approximately the middle between the walls 61a and 61c extending in the longitudinal direction of the frame 61. The wall 62 extends parallel or approximately parallel to the walls 61a and 61c and between the walls 61b and 61d. The wall 63 extends between the walls 61b and 61d extending in the lateral direction of the frame 61 at equal or approximately equal intervals and parallel or approximately parallel to the walls 61b and 61d. In this way, the walls 62 and 63 correspond to the six protrusion groups 5a of the structural membrane body 5, dividing the space surrounded by the frame 61 into a plurality of six spaces 6a.

[0042] The heights of the walls 61a to 61d, the wall 62, and the wall 63 of the frame 61 are the same or approximately the same, and are higher than the protruding height of the protruding portion 51 from the bottom 53 of the structural membrane 5 (see Figure 6).

[0043] As shown in FIG. 3 , the beam 6 is placed on the bottom 53 of the membrane 5 from the sound source side, and six projection groups 5a of the membrane 5 are accommodated in six spaces 6a defined by walls 62 and 63 within the space surrounded by the frame 61. That is, the columns 61a-61d of the frame 61 are placed on the outer periphery of the bottom 53 of the membrane 5. The wall 62 is placed between two rows of projection groups 5a along the columns 61a and 61c of the frame 61 at the bottom 53 of the membrane 5, and the wall 63 is placed between three rows of projection groups 5a along the columns 61b and 61d of the frame 61 at the bottom 53 of the membrane 5. The beam 6 is fixed to the bottom 53 of the membrane 5. The beam 6 is fixed to the bottom 53 of the structural membrane 5 by, for example, adhesive.

[0044] Fig. 6 is a cross-sectional view of the sound absorbing structure 1. As shown in Fig. 6, ends 61a1, 61b1, 61c1, and 61d1, which are the fixed side ends of pillar portions 61a, 61b, 61c, and 61d of frame portion 61, respectively, are in contact with and fixed to the bottom portion 53 of the structural membrane portion 5. Furthermore, end 62a, which is the fixed side end of pillar portion 62, is in contact with and fixed to the bottom portion 53 of the structural membrane portion 5. Furthermore, end 63a, which is the fixed side end of pillar portion 63, is in contact with and fixed to the bottom portion 53 of the structural membrane portion 5.

[0045] 6, the membrane structure 4 is placed on and fixed to the beam 6 from the sound source side. Specifically, ends 61a1, 61b1, 61c1, and 61d1 of the pillars 61a, 61b, 61c, and 61d of the frame 61, which are the sound source side ends, respectively, are in contact with and fixed to the outer peripheral end 4a, which is the end on the outer periphery of the membrane structure 4. Also, end 62a of the pillar 62, which is the sound source side end, is in contact with and fixed to a corresponding portion of the membrane structure 4, and similarly, end 63a of the pillar 63, which is the sound source side end, is in contact with and fixed to a corresponding portion of the membrane structure 4. The beam 6 is fixed to the membrane structure 4, for example, by adhesive or the like.

[0046] As described above, the membrane structure 4 and the structural membrane portion 5 are connected by the beams 6, and the membrane structure 4, the structural membrane portion 5, and the beams 6 are integrated to form the plate structure 2. As shown in FIG. 6, in the plate structure 2, a space of a predetermined width is formed between the highest protrusion 51 of the structural membrane portion 5 and the membrane structure 4. As shown in FIG. 6, the outer peripheral end 4a of the membrane structure 4 protrudes outward beyond the frame portion 61 of the beams 6.

[0047] As described above, the housing 3 is a member that forms the space 31 capable of accommodating the plate structure 2. The housing 3 is formed, for example, from a foam material, specifically, for example, foamed polypropylene. Note that the material of the housing 3 is not limited to foamed polypropylene, and other materials may be used. As shown in FIGS. 2, 3, and 6, the space 31 in the housing 3 is open to the sound source side and closed to the fixed side. The shape of the space 31 in a front view corresponds to the shape of the plate structure 2 in a front view. For example, the shape of the space 31 in a front view is wider on the outer periphery side than the outer periphery of the plate structure 2, for example, the frame portion 61 of the beam 6.

[0048] Specifically, as shown in FIGS. 2, 3, and 6, the housing 3 has a frame 32 that defines the outer peripheral edge of the space 31 and a bottom 33 that defines the fixed-side edge of the space 31. The frame 32 is formed by a plate-like wall extending in an annular shape. As shown in FIGS. 2, 3, and 6, the frame 32 extends in a rectangular annular shape and is formed by a series of plate-like walls 34, 35, 36, and 37 extending along four planes. The fixed-side end of the frame 32 is connected to the bottom 33, which closes the opening on the fixed side of the frame 32. As shown in FIG. 6, the walls 34, 35, 36, and 37 of the frame 32 face the walls 61a, 61b, 61c, and 61d of the frame 61 of the beam 6 of the plate structure 2, respectively, with gaps therebetween. As shown in FIG. 6, the heights of the walls 34, 35, 36, and 37 of the frame 32 are higher than the heights of the walls 61a, 61b, 61c, and 61d of the frame 61 of the beam 6 of the plate structure 2, respectively.

[0049] 6, the structural membrane 5 and beams 6 of the plate structure 2 are housed in a space 31 of the housing 3, and the plate structure 2 is attached to the housing 3. Specifically, the outer peripheral end 4a of the membrane structure 4 of the plate structure 2 is fixed in contact with ends 34a, 35a, 36a, and 37a, which are the sound source side ends of the walls 34, 35, 36, and 37 of the frame 32 of the housing 3. The outer peripheral end 4a of the membrane structure 4 of the plate structure 2 is fixed to the frame 32 of the housing 3 by, for example, adhesive or the like.

[0050] As described above, the structural membrane 5 and beam 6 of the plate structure 2 are housed in the space 31 of the housing 3, and the membrane structure 4 of the plate structure 2 is fixed to the housing 3 to form the sound absorbing structure 1. As shown in Figure 6, in the sound absorbing structure 1, a gap is formed between the structural membrane 5 of the plate structure 2 and the bottom 33 of the housing 3.

[0051] The sound-absorbing structure 1 has the above-described configuration, and in the sound-absorbing structure 1, the plate structure 2, which is composed of the membrane structure 4, structural membrane 5, and beams 6, forms a vibrating membrane that absorbs sound through membrane vibration. In other words, the plate structure 2, in which the membrane structure 4, structural membrane 5, and beams 6 are integrated, forms a resonator that resonates at a specific frequency and acts as an inertial mass. In addition, in the sound-absorbing structure 1, the space 31 in the housing 3 is closed by the membrane structure 4. The membrane structure 4 is airtight or suppresses air permeation, and the space 31 in the housing 3 is sealed by the membrane structure 4. Therefore, the air in the space 31 acts as an air spring against the plate structure 2, which vibrates. In this way, the sound-absorbing structure 1 forms a spring-mass resonance system.

[0052] As described above, the sound absorbing structure 1 forms a spring-mass resonant system and can absorb sounds in a desired frequency range.

[0053] The sound-absorbing structure 1 also has a structural membrane 5 supported by the membrane structure 4 via beams 6. The structural membrane 5 is a Helmholtz resonator designed for high frequencies. Therefore, high-frequency sounds that are not sufficiently absorbed by the membrane structure 4 and pass through the membrane structure 4 can be absorbed by the structural membrane 5, which is a Helmholtz resonator. Thus, the sound-absorbing structure 1 can absorb sounds not only through the spring-mass resonance system formed by the plate structure 2 and the housing 3, but also through the structural membrane 5, which is a Helmholtz resonator. This allows the sound-absorbing structure 1 to absorb sounds over a wide frequency range with a high sound absorption coefficient. Furthermore, in the membrane structure 4, the elastic membrane 20 attached to the membrane 10 has a lattice pattern and includes multiple through-holes 21. Therefore, the elastic membrane 20 allows high-frequency sounds that are not sufficiently absorbed by the membrane 10 to pass through to the structural membrane 5.

[0054] In addition, in the membrane structure 4, the air barrier membrane portion 12 and the elastic membrane portion 20, which is a lattice-shaped resin sheet, are integrally attached to the base membrane portion 11, which is a thin vibrating membrane. This increases the surface density and bending rigidity of the base membrane portion 11, which is a vibrating membrane. This allows the membrane structure 4 to absorb a wider range of sound frequencies, and also increases the sound absorption coefficient for sounds over a wide frequency range.

[0055] Furthermore, in the plate structure 2, the structural membrane portion 5 and the beams 6 are integrally attached to the membrane structure 4. This increases the surface density and bending rigidity of the membrane structure 4, which is a vibrating membrane. This allows the plate structure 5 to absorb a wider range of sound frequencies, and also increases the sound absorption coefficient for a wide frequency range.

[0056] Because the housing 3, structural membrane 5, and beams 6 are made from a foam material, the housing 3, structural membrane 5, and beams 6 can each absorb sound. Furthermore, the weight of the housing 3, structural membrane 5, and beams 6 can be reduced, making the sound-absorbing structure 1 lightweight. Furthermore, by manufacturing the housing 3, structural membrane 5, and beams 6 from the same foam material, such as foamed polypropylene, the sound-absorbing structure 1 can be produced efficiently.

[0057] In addition, the sound-absorbing structure 1 is made by combining multiple lightweight membrane-like members, and is capable of absorbing sounds over a wide frequency range with a high sound absorption coefficient while minimizing the increase in the weight of the sound-absorbing structure 1.

[0058] Furthermore, the sound-absorbing structure 1 can adjust the mass and rigidity of the plate structure 2 by changing the materials and thicknesses of the base membrane portion 11, elastic membrane portion 12, structural membrane portion 5, and beam body 6, thereby adjusting the sound absorption characteristics such as the frequency range of sound absorbed by the plate structure 2 and sound absorption efficiency.

[0059] As described above, the sound absorbing structure 1 according to the embodiment of the present invention can absorb sound over a wide frequency range while suppressing an increase in weight.

[0060] Although the present invention has been described above through the above embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0061] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the scope of the present invention. Furthermore, the above-described embodiments do not limit the scope of the present invention, and the present invention may include any and all applications. The components of the above-described embodiments, as well as their arrangement, materials, conditions, shape, size, etc., are not limited to those illustrated and may be modified as appropriate. For example, the present invention includes differences that arise during implementation due to manufacturing tolerances, etc. Furthermore, components illustrated in different embodiments may be partially substituted or combined within the scope of technical inconsistency. Furthermore, the various configurations may be selectively combined as appropriate to achieve at least some of the above-described problems and effects. [Explanation of symbols]

[0062] 1 sound absorbing structure, 2 plate structure, 3 housing, 4 membrane structure, 4a outer peripheral edge, 5 structural membrane portion, 5a protrusion group, 6 beam body, 6a space, 10 membrane body, 10a surface, 10b back surface, 11 membrane portion, 12 air permeation suppression membrane portion, 20 elastic membrane portion, 21 through hole, 31 space, 32 frame portion, 33 bottom portion, 34, 35, 36, 37 wall portion, 34a, 35a, 36a, 37a end portion, 51 protrusion portion, 52 space, 53 bottom portion, 54 top plate portion, 55 through hole, 61 frame portion, 61a, 61b, 61c, 61d, 62, 63 Wall part, 61a1,61b1,61c1,61d1,61a2,61b2,61c2,61d2,62a,63a,62b,63b end,

Claims

1. A plate structure that is a plate-like structure facing one side and the other side opposite to the one side; a housing that is a member that forms a space capable of accommodating the plate structure, the plate structure has a membrane structure which is a membrane-like member facing the one side and the other side, and a structural membrane portion facing the membrane structure toward the one side, the structural film portion has a plurality of protruding portions that protrude toward one side and form spaces; Sound-absorbing structure.

2. The membrane structure has a membrane body which is a membrane-like member and an elastic membrane portion which is a membrane-like member having elasticity, The membrane body has a pair of surfaces facing each other, the surfaces facing the one side and the other side, respectively. The sound absorbing structure according to claim 1 .

3. The elastic membrane portion has a plurality of through holes. The sound absorbing structure according to claim 2 .

4. The membrane is a member that suppresses air permeation. The sound absorbing structure according to claim 2 .

5. The membrane body has a base membrane portion which is a membrane-like member and an air barrier membrane portion which is a membrane-like member for blocking air. The sound absorbing structure according to claim 4.

6. The air barrier membrane portion is made of resin. The sound absorbing structure according to claim 5.

7. The base film portion and the air barrier film portion are bonded to each other. The sound absorbing structure according to claim 5 or 6.

8. The structural membrane portion is a Helmholtz resonator. The sound absorbing structure according to claim 1 .

9. The structural membrane portion is formed from a foam. The sound absorbing structure according to claim 1 or 8.

10. The plate structure further includes a beam between the membrane structure and the structural membrane portion, The beam supports the structural membrane portion relative to the membrane structure. The sound absorbing structure according to claim 1 .

11. The beam defines a space for accommodating the plurality of protrusions of the structural membrane portion. The sound absorbing structure according to claim 10.

12. The beam body is lattice-shaped.

12. A sound absorbing structure according to claim 11.

13. The beam is formed from a foam. The sound absorbing structure according to claim 10.

14. The housing is formed from foam. The sound absorbing structure according to claim 1 .

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