Sound-absorbing structure

Abstract

The purpose of the present invention is to suppress the occurrence of unpleasant, aversion, and fear due to the appearance. A sound-absorbing structure (1) is provided with a relief structure section (10). The undulating structure section (10) has a plurality of protruding sections (20) that protrude toward the sound source side. Each of the projections (20) has an upper wall portion (21) and a side wall portion (25) that form the diaphragm (2), and a space (22) is formed on a fixed side opposite to the sound source side with respect to the upper wall portion (21). The side wall part (25) is a cylindrical part extending from the lateral end of the upper wall part (21) to the fixed side, and surrounds the space (22) from the lateral direction. The undulating structure part (10) is a porous body having individual bubbles formed from a thermoplastic resin.

Description

Technical Field

[0001] This invention relates to sound-absorbing structures. Background Technology

[0002] In the past, various soundproofing structures have been proposed for sound insulation. Among these structures are plate-shaped soundproofing panels used for walls, etc. These panels incorporate sound-absorbing structures that function to absorb sound. For example, there are sound-absorbing structures with an undulating structure having multiple protrusions that divide sound-absorbing spaces. Among these sound-absorbing structures with multiple protrusions, there are sound-absorbing structures with Helmholtz resonators arranged in various shapes (see, for example, Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 3306610. Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] To achieve sound absorption, Helmholtz resonators are formed with holes for guiding vibrating air into the internal sound-absorbing space. Therefore, multiple holes are arranged in a sound-absorbing structure formed by arranging multiple Helmholtz resonators as described above. When the multiple Helmholtz resonators included in the sound-absorbing structure have various shapes, they are irregularly arranged, and therefore, the multiple holes are also irregularly arranged. Such multiple holes can sometimes cause discomfort or aversion in those who see them; in addition, they can sometimes instill fear.

[0008] Therefore, conventional sound-absorbing structures formed by arranging multiple Helmholtz resonators must be designed to prevent appearances that evoke feelings of displeasure, aversion, or fear. Similarly, conventional sound-absorbing structures with multiple protrusions forming sound-absorbing spaces must be designed to prevent appearances that evoke feelings of displeasure, aversion, or fear.

[0009] The present invention was made in view of the above-mentioned problems, and its object is to provide a sound-absorbing structure that can suppress feelings of displeasure, disgust, and fear caused by appearance.

[0010] Means for solving technical problems

[0011] To achieve the above objectives, the sound-absorbing structure of the present invention comprises an undulating structure having a plurality of protrusions protruding toward one side, each of the protrusions having an upper wall portion and a side wall portion forming a vibrating diaphragm, and a space being formed on the other side relative to the upper wall portion, the other side being the side opposite to the first side, the side wall portion being a cylindrical portion extending from the lateral end of the upper wall portion toward the other side, laterally surrounding the space, the undulating structure being a porous body having independent air bubbles formed of thermoplastic resin.

[0012] In one aspect of the sound-absorbing structure, the sidewall portion forms a plurality of vibrating diaphragms.

[0013] In one aspect of the sound-absorbing structure of the present invention, the sidewall portion is formed with four diaphragms, two of the four diaphragms being opposed to each other across the space, and the other two of the four diaphragms being opposed to each other across the space in a direction intersecting the direction of the two opposing diaphragms.

[0014] In one embodiment of the present invention, the thermoplastic resin is any one of polypropylene, polyethylene, and polystyrene.

[0015] In one aspect of the sound-absorbing structure of the present invention, the foaming ratio of the porous material is more than 20 times and less than 30 times.

[0016] In one aspect of the sound-absorbing structure of the present invention, the thickness of the undulating structure is 3 mm or more and 7 mm or less.

[0017] In one embodiment of the present invention, the thickness of the diaphragm is 3 mm or more and 7 mm or less.

[0018] In a sound-absorbing structure according to one aspect of the present invention, the plurality of protrusions include a plurality of different types of protrusions.

[0019] In a sound-absorbing structure according to one aspect of the invention, the plurality of types of protrusions include at least one of the size and shape of the protrusions.

[0020] Invention Effects

[0021] The sound-absorbing structure according to the present invention can suppress feelings of displeasure, aversion, and fear caused by appearance. Attached Figure Description

[0022] Figure 1 This is an exploded perspective view showing the schematic structure of the sound-absorbing structure according to an embodiment of the present invention.

[0023] Figure 2 This is a three-dimensional cross-sectional view showing a portion of a cross-section of a sound-absorbing structure.

[0024] Figure 3 This is a three-dimensional cross-sectional view showing a portion of a cross-section of a sound-absorbing structure.

[0025] Figure 4 This is a graph showing the sound absorption efficiency of a sound-absorbing structure according to an embodiment of the present invention and the sound absorption efficiency of a conventional sound-absorbing structure formed by arranging multiple Helmholtz resonators. Detailed Implementation

[0026] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Additionally, in the drawings, sometimes not all structural elements are labeled with reference numerals, and reference numerals for a portion of the structural elements are omitted.

[0027] Figure 1 This is an exploded perspective view showing the schematic structure of the sound-absorbing structure 1 according to an embodiment of the present invention. Figure 2 , Figure 3 This is a perspective cross-sectional view showing a portion of the sound-absorbing structure 1. Additionally, in Figure 1 , Figure 2 The image shows the sound-absorbing structure 1 as viewed from the front side. Figure 3 The image shows the sound-absorbing structure 1 as viewed from the rear side. (See image for reference.) Figures 1-3 As shown, the sound-absorbing structure 1 includes an undulating structure portion 10. The undulating structure portion 10 has multiple protrusions 20 projecting towards one side (i.e., the sound source side). Each protrusion 20 has an upper wall portion 21 and a side wall portion 25 forming a diaphragm. Furthermore, a space 22 is formed on the other side (i.e., the fixed side) opposite to the sound source side of the upper wall portion 21. The side wall portion 25 is a cylindrical portion extending laterally from the lateral end of the upper wall portion 21 towards the fixed side, which is the other side, and laterally surrounds the space 22. The undulating structure portion 10 is a porous body having independent air bubbles formed from thermoplastic resin. The structure of the sound-absorbing structure 1 will be specifically described below.

[0028] Furthermore, the sound source side refers to the side facing the imaginary plane side, which is the side that becomes the sound source side for which sound absorption is desired when the sound-absorbing structure 1 is in use. Conversely, the fixed side refers to the other side facing the imaginary plane side, which is the side that becomes the fixed object side for fixing the sound-absorbing structure 1 when it is in use.

[0029] like Figures 1-3As shown, the undulating structure 10 of the sound-absorbing structure 1 has, for example, the same shape as a known sound-absorbing structure formed by arranging multiple Helmholtz resonators. In the undulating structure 10, multiple protrusions 20 are arranged along an imaginary plane. Each of the multiple protrusions 20 of the undulating structure 10 has an upper wall portion 21 forming a diaphragm and a side wall portion 25 forming a diaphragm, as described above. The side wall portion 25 extends from the lateral end of the upper wall portion 21 toward the fixed side, and the upper wall portion 21 and the side wall portion 25 form a recess that is recessed toward the sound source side, dividing a space 22. The space 22 is open to the fixed side. In addition, "lateral" refers to the side orthogonal to the direction toward the sound source side or the fixed side. The lateral end of the upper wall portion 21 is the end of the outer peripheral side of the upper wall portion 21.

[0030] like Figures 1-3 As shown, the upper wall portion 21 extends in a membrane-like manner and has two opposing faces, namely a surface 23 and a back surface 24. Surface 23 faces the sound source side, and the back surface 24 faces the stationary side. The thickness (thickness T1) of the upper wall portion 21 is the same or approximately the same. That is, in the upper wall portion 21, the distance between surface 23 and back surface 24 is generally constant or approximately constant. In addition, the upper wall portion 21 extends along a plane; for example, surface 23 extends parallel or approximately parallel to an imaginary plane, and similarly, back surface 24 extends parallel or approximately parallel to this imaginary plane. Furthermore, surface 23 and back surface 24 are, for example, parallel or approximately parallel. In addition, the upper wall portion 21 is, for example, inclined non-orthogonal to the direction towards the sound source side, and surface 23 and back surface 24 are also inclined non-orthogonal to the direction towards the sound source side. Alternatively, the upper wall portion 21 may be orthogonal to the direction towards the sound source side, and surface 23 and back surface 24 may also be orthogonal to the direction towards the sound source side. Surface 23 may be a plane or a curved surface. Similarly, the back surface 24 can be either flat or curved. Additionally, as... Figures 1-3 As shown, the shape of the upper wall portion 21 when viewed from the sound source side or the fixed side is, for example, rectangular or approximately rectangular. In addition, the shape of the upper wall portion 21 when viewed from the sound source side or the fixed side is not limited to a rectangle, but may also be a triangle, approximately triangular or other polygons or approximately other polygons, a circle or approximately circular or other shapes.

[0031] like Figure 2 As shown, the sidewall portion 25 has an opening 20b at its fixed-side end (i.e., lower end 20a) that opens the space 22 toward the fixed side. Furthermore, the lower end 20a is the fixed-side end of each protrusion 20. The sidewall portion 25 has a shape corresponding to the shape of the upper wall portion 21 and has one or more membrane-like sidewall sheets. Figures 1-3As shown, the shape of the sidewall portion 25 is, for example, a rectangular or approximately rectangular tube with a rectangular cross-section. The shape of the sidewall portion 25 is not limited to a rectangular or approximately rectangular tube with a rectangular cross-section; it can be various shapes corresponding to the shape of the upper wall portion 21. The thickness (thickness T2) of the sidewall portion 25 is, for example, the same or approximately the same. Furthermore, the thickness T2 of the sidewall portion 25 is, for example, the same or approximately the same as the thickness T1 of the upper wall portion 21. Additionally, the thickness T2 of the sidewall portion 25 may not be continuous, and it may not be the same as the thickness T1 of the upper wall portion 21. Furthermore, no through hole is formed in the upper wall portion 21.

[0032] Specifically, for example, such as Figures 1-3 As shown, the sidewall portion 25 has four sidewall plates 25a, 25b, 25c, and 25d. The sidewall plates 25a, 25b, 25c, and 25d are portions extending laterally from each side of the upper wall portion 21. The sidewall plates 25a, 25b, 25c, and 25d are sequentially connected in the circumferential direction. Similar to the upper wall portion 21, the sidewall plates 25a, 25b, 25c, and 25d each have a surface 25aa and a back surface 25ab, a surface 25ba and a back surface 25bb, a surface 25ca and a back surface 25cb, and a surface 25da and a back surface 25db, respectively, which are film-like extensions with a thickness T2 that is generally the same or approximately the same. Furthermore, the thicknesses of the sidewall portions 25a, 25b, 25c, and 25d are respectively the distance between surface 25aa and back surface 25ab, the distance between surface 25ba and back surface 25bb, the distance between surface 25ca and back surface 25cb, and the distance between surface 25da and back surface 25db. Additionally, the thickness T2 of each of the sidewall portions 25a, 25b, 25c, and 25d is the same as or approximately the same as the thickness T1 of the upper wall portion 21. Alternatively, the thickness T2 of each of the sidewall portions 25a, 25b, 25c, and 25d may not be the same as the thickness T1 of the upper wall portion 21.

[0033] Sidewall portions 25a, 25b, 25c, and 25d extend along planes. For example, surfaces 25aa, 25ba, 25ca, and 25da extend parallel to or substantially parallel to imaginary planes. Similarly, back surfaces 25ab, 25bb, 25cb, and 25db extend parallel to or substantially parallel to these imaginary planes. Furthermore, surfaces 25aa, 25ba, 25ca, and 25da, and back surfaces 25ab, 25bb, 25cb, and 25db, are, for example, parallel or substantially parallel. Additionally, sidewall portions 25a, 25b, 25c, and 25d are, for example, inclined relative to the direction toward the sound source, and surfaces 25aa, 25ba, 25ca, and 25da, and back surfaces 25ab, 25bb, 25cb, and 25db are, for example, inclined relative to the direction toward the sound source. Additionally, the sidewall portions 25a, 25b, 25c, and 25d can also be parallel to the direction facing the sound source, and the surfaces 25aa, 25ba, 25ca, and 25da and the back surfaces 25ab, 25bb, 25cb, and 25db can also be parallel to the direction facing the sound source. The surfaces 25aa, 25ba, 25ca, and 25da and the back surfaces 25ab, 25bb, 25cb, and 25db can be planar or curved surfaces. Furthermore, as... Figures 1-3 As shown, the shapes of the sidewall portions 25a, 25b, 25c, and 25d are, for example, rectangular or approximately rectangular. Furthermore, the shapes of the sidewall portions 25a, 25b, 25c, and 25d are not limited to rectangular; they can also be other shapes.

[0034] As described above, the upper wall portion 21 and the side wall portion 25 form a vibrating membrane. The vibrating membrane is the portion that vibrates in the spring-mass resonance system described later. Specifically, vibrating membranes are formed in the side wall portions 25a, 25b, 25c, and 25d of the side wall portion 25. In the upper wall portion 21, the extended portions of the surface 23 and the back surface 24 form a vibrating membrane as a whole. Alternatively, a portion of the extended portions of the surface 23 and the back surface 24 in the upper wall portion 21 may also form a vibrating membrane. For example, a portion with high rigidity, excluding the ends of the extended portions of the surface 23 and the back surface 24, may form a vibrating membrane. Similarly, in the side wall portion 25a, the extended portions of the surface 25aa and the back surface 25ab form a vibrating membrane as a whole. Alternatively, a portion of the extended portions of the surface 25aa and the back surface 25ab in the side wall portion 25a may also form a vibrating membrane. For example, a portion with high rigidity, excluding the ends of the widened portions of the surface 25aa and the back surface 25ab, may form a vibrating membrane. Similarly, in sidewall plate 25b, the extended portions of surface 25ba and back surface 25bb integrally form a vibrating membrane. Alternatively, a portion of the extended portions of surface 25ba and back surface 25bb in sidewall plate 25b may also form a vibrating membrane. For example, a portion with high rigidity, excluding the ends of the extended portions of surface 25ba and back surface 25bb, may form a vibrating membrane. Similarly, in sidewall plate 25c, the extended portions of surface 25ca and back surface 25cb integrally form a vibrating membrane. Alternatively, a portion of the extended portions of surface 25ca and back surface 25cb in sidewall plate 25c may also form a vibrating membrane. For example, a portion with high rigidity, excluding the ends of the extended portions of surface 25ca and back surface 25cb, may form a vibrating membrane. Similarly, in sidewall plate 25d, the extended portions of surface 25da and back surface 25db integrally form a vibrating membrane. Alternatively, a portion of the extended portions of surface 25da and back surface 25db in sidewall plate 25d may also form a vibrating membrane. For example, the portion with high rigidity, except for the portion extending 25 da on the surface and 25 db on the back, forms a vibrating diaphragm.

[0035] The undulating structure 10 has multiple protrusions 20, including multiple types of protrusions 20. The multiple types of protrusions 20 include at least one of the sizes and shapes of the protrusions 20. For example... Figures 1-3As shown, the undulating structure 10 has, for example, multiple protrusions 20 with different sizes in the upper wall portion 21 and the space 22. Specifically, for example, the undulating structure 10 has multiple protrusions 20 with at least one difference in the size of the upper wall portion 21, the size of each of the side wall pieces 25a, 25b, 25c, and 25d, the height of the side wall portion 25, the shape of the upper wall portion 21, and the shape of each of the side wall pieces 25a, 25b, 25c, and 25d. Alternatively, the undulating structure 10 may have multiple protrusions 20 of the same type. Alternatively, the undulating structure 10 may not have multiple protrusions 20 of the same type.

[0036] In addition, such as Figures 1-3 As shown, the undulating structure 10 has, for example, a bottom 26. The bottom 26 is a portion extending toward a fixed side, from which a plurality of protrusions 20 protrude, each protruding 20 having an opening 20b located on the bottom 26. The bottom 26 is a portion extending along an imaginary plane, extending between adjacent protrusions 20. The bottom 26 extends obliquely relative to the upper wall portion 21 of each of the plurality of protrusions 20, for example. Alternatively, the bottom 26 may extend parallel to the upper wall portion 21 of each of the plurality of protrusions 20. The bottom 26 has a pair of mutually opposing surfaces, namely an upper surface 26a and a lower surface 26b, from which the plurality of protrusions 20 protrude toward the sound source side, and the openings 20b of the plurality of protrusions 20 are formed on the lower surface 26b. The upper surface 26a is, for example, a surface extending on a plane or a substantially plane, and the lower surface 26b is, for example, a surface extending on a plane or a substantially plane. In addition, the surface 26a above may not be a plane extending on a plane, for example, it may be a surface extending on a curved surface. Similarly, the surface 26b below may not be a plane extending on a plane, for example, it may be a surface extending on a curved surface.

[0037] The sound-absorbing structure 1 has the above-described structure, with each protrusion 20 forming a spring-mass resonance system. Specifically, in each protrusion 20, the sidewall plates 25a, 25b, 25c, and 25d of the upper wall portion 21 and the sidewall portion 25 respectively form a vibrating diaphragm that absorbs sound through diaphragm vibration. That is, the upper wall portion 21 and the sidewall plates 25a, 25b, 25c, and 25d each form a resonator that resonates at a specific frequency, thus functioning as inertial mass. In particular, a resonator is formed at or near the center of each of the upper wall portion 21 and the sidewall plates 25a, 25b, 25c, and 25d, functioning as inertial mass. Furthermore, in the working state of the sound-absorbing structure 1, the space 22 of each protrusion 20 is closed, and the air within the space 22 of each protrusion 20 acts as an air spring on the upper wall portion 21 and the sidewall plates 25a, 25b, 25c, and 25d that vibrate the diaphragm. In this way, the sound-absorbing structure 1 forms a spring-mass resonance system, capable of absorbing sound within the desired frequency range. Furthermore, the sound-absorbing structure 1 is mounted on a fixed component such as a soundproof wall or partition, with the bottom surface 26b of the bottom 26 facing the fixed component, thus enclosing the spaces 22 of each protrusion 20. Alternatively, the sound-absorbing structure 1 may also have a sealing component that encloses the spaces 22 formed by the multiple protrusions 20. This sealing component, for example, is a plate-shaped component with a surface facing the bottom surface 26b of the bottom 26, mounted on the undulating structure 10, and enclosing the spaces 22 formed by the multiple protrusions 20.

[0038] As described above, the sound-absorbing structure 1 does not have through holes in the upper wall portion 21 of the multiple protrusions 20, which can suppress the feelings of displeasure, disgust, and fear that people feel when they see the sound-absorbing structure 1, as is the case with conventional sound-absorbing structures formed by multiple Helmholtz resonators.

[0039] As described above, the undulating structure 10 is a porous body having independent air bubbles formed from thermoplastic resin. That is, the undulating structure 10 is a body of independent air bubbles formed from thermoplastic resin, and the air bubbles inside the undulating structure 10 are independent air bubbles. The thermoplastic resin forming the undulating structure 10 is, for example, any one of polypropylene, polyethylene, and polystyrene. However, the thermoplastic resin forming the undulating structure 10 is not limited to these and may be other thermoplastic resins. Furthermore, the foaming ratio of the undulating structure 10 is 20 times or more and 30 times or less. For example, the foaming ratio of the undulating structure 10 is 25 times.

[0040] Furthermore, the thickness T1 of the upper wall portion 21 of the undulating structure portion 10 is 3 mm or more and 7 mm or less. Additionally, the thickness T1 of the upper wall portion 21 of the undulating structure portion 10 is, for example, 5 mm or approximately 5 mm. Furthermore, the thickness T2 of each of the side wall portions 25a, 25b, 25c, and 25d of the side wall portion 25 is, for example, 3 mm or more and 7 mm or less. Additionally, the thickness T2 of each of the side wall portions 25a, 25b, 25c, and 25d is, for example, 5 mm or approximately 5 mm. Thus, the thickness T1 of the upper wall portion 21 and the thickness T2 of each of the side wall portions 25a, 25b, 25c, and 25d of the side wall portion 25 are, for example, the same or approximately the same. That is, the thickness of each of the plurality of protrusions 20 is the same or approximately the same, being 3 mm or more and 7 mm or less, and, for example, 5 mm or approximately 5 mm. Furthermore, the thickness of the bottom 26 can be the same as or approximately the same as the thickness T1 of the upper wall portion 21 and the thickness T2 of each of the side wall plates 25a, 25b, 25c, and 25d of the side wall portion 25. That is, the thickness of the undulating structure portion 10 can be the same or approximately the same. In this case, the thickness of the undulating structure portion 10 is, for example, 3 mm or more and 7 mm or less, or for example, 5 mm or approximately 5 mm.

[0041] Furthermore, the thickness T1 of the diaphragm of the upper wall portion 21 of the undulating structure portion 10 can be 3 mm or more and 7 mm or less. Additionally, the thickness T1 of the diaphragm of the upper wall portion 21 of the undulating structure portion 10 can, for example, be 5 mm or approximately 5 mm. Furthermore, the thickness T2 of the diaphragm of each of the sidewall plates 25a, 25b, 25c, and 25d of the sidewall portion 25 can, for example, be 3 mm or more and 7 mm or less. Additionally, the thickness T2 of the diaphragm of each of the sidewall plates 25a, 25b, 25c, and 25d can, for example, be 5 mm or approximately 5 mm. Thus, the thickness T1 of the diaphragm of the upper wall portion 21 and the thickness T2 of the diaphragm of each of the sidewall plates 25a, 25b, 25c, and 25d of the sidewall portion 25 can be the same or approximately the same.

[0042] As described above, the undulating structure 10 is a porous body formed of thermoplastic resin, and the internal air bubbles of the undulating structure 10 are independent air bubbles. Therefore, a vibrating membrane can be formed in the undulating structure 10, and the undulating structure 10 can have high flexibility, which in turn allows the formed vibrating membrane to have high flexibility. Thus, the sidewall portions 25a, 25b, 25c, and 25d of the upper wall portion 21 and sidewall portion 25 of each of the plurality of protrusions 20 can each have high flexibility, thereby expanding the range of resonant frequencies of the membrane vibration that can be set at the upper wall portion 21 and the sidewall portions 25a, 25b, 25c, and 25d respectively. That is, the range of resonant frequencies of the membrane vibration of the upper wall portion 21 and the sidewall portions 25a, 25b, 25c, and 25d, which can be set by adjusting the thickness of each of the upper wall portion 21 and the sidewall portions 25a, 25b, 25c, and 25d, is wider.

[0043] Furthermore, by setting the thickness of each protrusion 20, specifically the thicknesses T1 and T2 of the upper wall portion 21 and the side wall portions 25a, 25b, 25c, and 25d of the side wall portions 25 of each protrusion 20 to 3 mm or more and 7 mm or less, the sound absorption rate of each protrusion 20 can be improved. Furthermore, by setting the thickness of each protrusion 20, specifically the thicknesses T1 and T2 of the upper wall portion 21 and the side wall portions 25a, 25b, 25c, and 25d of the side wall portions 25 of each protrusion 20 to 5 mm or approximately 5 mm, the sound absorption rate of each protrusion 20 can be further improved.

[0044] The undulating structure 10 can be formed, for example, by vacuum forming a porous sheet with independent air bubbles formed of thermoplastic resin. The thermoplastic resin is, for example, any one of polypropylene, polyethylene, or polystyrene. The foaming ratio of the porous sheet with independent air bubbles formed of thermoplastic resin is, for example, 20 times or more and 30 times or less. Furthermore, the porous sheet with independent air bubbles formed of thermoplastic resin is, for example, a sheet of uniform or approximately uniform thickness, with a thickness of 3 mm or more and 7 mm or less. Alternatively, the thickness of the porous sheet is 5 mm or approximately 5 mm.

[0045] Figure 4 A graph showing the sound absorption efficiency of the sound-absorbing structure 1 as an example and the sound absorption efficiency of a conventional sound-absorbing structure formed by arranging multiple Helmholtz resonators as an example is presented. The conventional sound-absorbing structure has the same shape as the undulating structure 10 of the sound-absorbing structure 1, but through holes are formed on the upper wall of each protrusion; furthermore, the undulating structure is not a porous material. The thermoplastic resin forming the undulating structure 10 of the sound-absorbing structure 1 as an example is polypropylene, with a foaming ratio of 25, and the thickness of the undulating structure 10 is 5 mm. The measured sound absorption rate is the reverberation chamber method sound absorption rate, and the value is determined based on the reverberation chamber method sound absorption rate measurement method of JIS A 1409. The resin forming the conventional sound-absorbing structure as an example is polypropylene, and the thickness of the undulating structure is 1 mm.

[0046] like Figure 4 As shown, the sound absorption efficiency of the sound-absorbing structure 1 is higher than that of the previous sound-absorbing structure formed by arranging multiple Helmholtz resonators.

[0047] In this way, the sound-absorbing structure 1 can form a high-efficiency sound-absorbing structure through a spring-mass resonance system without utilizing Helmholtz resonance.

[0048] As described above, the sound-absorbing structure 1 according to the embodiments of the present invention can suppress feelings of displeasure, aversion, and fear caused by appearance. Furthermore, the sound-absorbing structure 1 according to the embodiments of the present invention can suppress feelings of displeasure, aversion, and fear caused by appearance and achieves a high sound absorption effect.

[0049] The present invention has been described above through the above embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments. Those skilled in the art should understand that various modifications or improvements can be made to the above embodiments. As will be known from the claims, such modifications or improvements can also be included within the technical scope of the present invention.

[0050] The embodiments described above are for ease of understanding of the present invention and are not intended to limit or explain the present invention. Furthermore, the above embodiments do not limit the scope of application of the present invention; the present invention can include all objects as its objects. The constituent elements, their arrangement, materials, conditions, shapes, and dimensions, etc., provided in the above embodiments are not limited to the examples shown and can be appropriately modified. For example, the present invention includes differences arising from manufacturing tolerances, etc. Furthermore, within the scope of technical non-contradiction, the constituent elements shown in different embodiments can be partially substituted or combined with each other. Additionally, the structures can be appropriately and selectively combined to achieve at least a portion of the aforementioned problems and effects.

[0051] Symbol Explanation

[0052] 1: Sound-absorbing structure;

[0053] 10: Undulating structural section;

[0054] 20: Protrusion;

[0055] 20a: Lower end;

[0056] 20b: Open;

[0057] 21: Upper wall part;

[0058] 22: Space;

[0059] 23: Surface;

[0060] 24: Back side;

[0061] 25: Side wall portion;

[0062] 25a, 25b, 25c, 25d: Sidewall plates;

[0063] 25aa, 25ba, 25ca, 25da: surface;

[0064] 25ab, 25bb, 25cb, 25db: Back side;

[0065] 26: Bottom;

[0066] 26a: Above;

[0067] 26b: Bottom surface;

[0068] T1, T2: Thickness.

Claims

1. A sound-absorbing structure having an undulating structural portion, The undulating structure has multiple protrusions that project to one side. Each of the protrusions has an upper wall portion and a side wall portion forming a vibrating diaphragm, and a space is formed on the opposite side relative to the upper wall portion, the opposite side being the side opposite to the first one. The sidewall portion is a cylindrical section extending from one lateral end of the upper wall portion toward the other side, laterally enclosing the space. The undulating structure is a porous body with independent air bubbles formed from thermoplastic resin.

2. The sound-absorbing structure according to claim 1, wherein, The sidewall portion forms multiple vibrating membranes.

3. The sound-absorbing structure according to claim 2, wherein, The sidewall portion has four vibrating diaphragms. Two of the four vibrating diaphragms are positioned opposite each other across the space. The other two of the four diaphragms are positioned opposite each other across the space in a direction that intersects the directions of the two diaphragms opposite to the first two diaphragms.

4. The sound-absorbing structure according to claim 1, wherein, The thermoplastic resin is any one of polypropylene, polyethylene, and polystyrene.

5. The sound-absorbing structure according to claim 1 or 4, wherein, The foaming ratio of the porous material is more than 20 times and less than 30 times.

6. The sound-absorbing structure according to claim 5, wherein, The thickness of the undulating structure is more than 3 mm and less than 7 mm.

7. The sound-absorbing structure according to claim 5, wherein, The thickness of the vibrating diaphragm is more than 3 mm and less than 7 mm.

8. The sound-absorbing structure according to claim 1, wherein, The plurality of protrusions includes multiple types of protrusions.

9. The sound-absorbing structure according to claim 1, wherein, The multiple types of protrusions include at least one of the size and shape of the protrusions.

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