Sound-absorbing structure and tire

Abstract

This sound absorbing structure comprises: a box body having an opening; and a hollow neck part communicating with the opening and extending to a hollow part side of the box body, wherein the opening is formed in a side part of the box body. This tire includes the sound absorbing structure attached to an internal cavity part.

Description

Technical Field

[0001] The present disclosure relates to a sound-absorbing structure and a tire.

Background Art

[0002] Patent Document 1 describes a sound-absorbing structure that reduces vibrations in a cavity by Helmholtz resonance. This sound-absorbing structure is attached to the inner cavity of a tire to reduce the tire inner cavity resonance sound generated during vehicle travel. This sound-absorbing structure includes a sub-chamber forming portion that forms a sub-chamber and has an opening.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The tire inner cavity resonance sound generated during vehicle travel is in a low frequency band of, for example, about 200 Hz to 300 Hz. In the sound-absorbing structure described in Patent Document 1, it is possible to reduce such resonance sound in the low frequency band by increasing the length of the opening. However, the opening is formed in the top portion of the sub-chamber forming portion directed toward the center in the radial direction of the tire and extends in the thickness direction of the sound-absorbing structure. Therefore, in order to increase the length of the opening, there is a problem that the sound-absorbing structure becomes thick. When the sound-absorbing structure becomes thick, the sound-absorbing structure becomes large, which may impede the flow of air in the tire inner cavity. In addition, the sound-absorbing structure becomes heavy, which may easily reduce the rotational balance of the tire.

[0005] An object of the present disclosure is to provide a sound-absorbing structure that can easily reduce the resonance sound in the low frequency range while making the thickness thin, and a tire to which this sound-absorbing structure is attached.

Means for Solving the Problems

[0006] The sound-absorbing structure according to the present disclosure includes a box body having an opening and a hollow neck portion communicating with the opening and extending toward the hollow portion side of the box body, and the opening is formed on a side portion of the box body.

[0007] In this sound-absorbing structure, since it includes a box body having an opening and a hollow neck portion communicating with the opening and extending toward the hollow portion side of the box body, the sound-absorbing structure can function as a Helmholtz resonator, and by making the neck portion longer, Helmholtz resonance of the resonance frequency in the low frequency range can be generated. And since the opening is formed on the side portion of the box body, it is directed in a direction intersecting the thickness direction of the sound-absorbing structure. For this reason, the neck portion communicating with the opening can also be easily extended in a direction intersecting the thickness direction of the sound-absorbing structure. That is, the neck portion can be made longer without making the sound-absorbing structure thicker. For this reason, it is possible to easily reduce the thickness while reducing the resonance sound in the low frequency range.

[0008] In the above-described sound-absorbing structure, the side portion may extend in a direction intersecting the direction orthogonal to the thickness direction of the sound-absorbing structure. In this sound-absorbing structure, since the side portion extends in a direction intersecting the direction orthogonal to the thickness direction of the sound-absorbing structure, it is possible to easily reduce the thickness of the sound-absorbing structure.

[0009] In the above-described sound-absorbing structure, the neck portion may extend in a direction orthogonal to the thickness direction. In this sound-absorbing structure, since the neck portion extends in a direction orthogonal to the thickness direction, it is possible to easily reduce the thickness of the sound-absorbing structure while reducing the resonance sound in the low frequency range.

[0010] In the above-described sound absorption structure, the neck portion may have a fixing portion that is fixed to the box body at a position at least separated from the opening. In this sound absorption structure, by having a fixing portion in which the neck portion is fixed to the box body at a position at least separated from the opening, movement of the neck portion with respect to the box body can be suppressed. For this reason, for example, when an external force such as centrifugal force or vibration acts on the sound absorption structure, it is possible to suppress excessive displacement of the neck portion with respect to the box body.

[0011] In the above-described sound absorption structure, the opening may be a circular hole. In this sound absorption structure, by the opening being a circular hole, design as a Helmholtz resonator can be easily performed.

[0012] In the above-described sound absorption structure, the opening may be a slit extending linearly. In this sound absorption structure, by the opening being a slit extending linearly, manufacture of the sound absorption structure can be easily performed.

[0013] In the above-described sound absorption structure, a porous sound absorber housed in the hollow portion of the box body may be further provided. In this sound absorption structure, by providing a porous sound absorber, sound in the high frequency range can be reduced.

[0014] In the above-described sound absorption structure, the box body may have at least one of a Shore A hardness of 40 or more and 100 or less and a Shore D hardness of 10 or more and 70 or less. In this sound absorption structure, by the box body having at least one of a Shore A hardness of 40 or more and 100 or less and a Shore D hardness of 10 or more and 70 or less, while suppressing deformation due to external forces such as centrifugal force and vibration, the followability with respect to the mounting target surface can be enhanced.

[0015] In the above-described sound absorption structure, the box body may have an elastomer. In this sound absorption structure, by the box body having an elastomer, while suppressing deformation due to external forces such as centrifugal force and vibration, the followability with respect to the mounting target surface can be enhanced.

[0016] In the above-described sound-absorbing structure, the box body has a top portion, and the side portions may be connected to the peripheral edge of the top portion and extend in a direction intersecting the extending direction of the top portion. In this sound-absorbing structure, since the box body has a top portion and side portions that are connected to the peripheral edge of the top portion and extend in a direction intersecting the extending direction of the top portion, the upper part of the hollow portion can be covered by the top portion.

[0017] In the above-described sound-absorbing structure, the box body may further have a bottom portion that is connected to the side portions and faces the top portion. In this sound-absorbing structure, since the box body has a bottom portion that is connected to the side portions and faces the top portion, the sound-absorbing structure alone can function as a Helmholtz resonator. Therefore, for example, even if a gap is formed between the sound-absorbing structure and the mounting target surface, the sound-absorbing structure can function as a Helmholtz resonator.

[0018] In the above-described sound-absorbing structure, the box body has a plurality of openings and a partition wall that is connected to the top portion and the side portions and divides the hollow portion into two small spaces. The partition wall may divide the hollow portion such that at least one opening communicates with each of the two small spaces. In this sound-absorbing structure, the hollow portion of the box body is divided into two small spaces by the partition wall, and at least one opening communicates with each of the two small spaces, so that each of the two small spaces can function as a Helmholtz resonator while increasing the rigidity of the sound-absorbing structure.

[0019] In the above-described sound-absorbing structure, the partition wall may divide the hollow portion such that one opening communicates with each of the two small spaces. In this sound-absorbing structure, since one opening communicates with each of the two small spaces, the sound-absorbing structure can be divided into Helmholtz resonator units.

[0020] In the above-described sound-absorbing structure, the partition wall has a first partition wall portion located on one side of the two small spaces and a second partition wall portion located on the other side of the two small spaces, and the top portion and the side portion may be divided by the first partition wall portion and the second partition wall portion. In this sound-absorbing structure, since the top portion and the side portion are divided by the first partition wall portion and the second partition wall portion, it becomes easier to bend or flex the sound-absorbing structure. Thereby, the followability to the mounting target surface can be further enhanced.

[0021] In the above-described sound-absorbing structure, the first partition wall portion and the second partition wall portion may be arranged such that the distance between them increases as they go toward the top portion. In this sound-absorbing structure, since the first partition wall portion and the second partition wall portion are arranged such that the distance between them increases as they go toward the top portion, it becomes easier to bend or flex the sound-absorbing structure so that the top surface side is on the inner side.

[0022] In the above-described sound-absorbing structure, the first partition wall portion and the second partition wall portion may be connected to each other at the end opposite to the top portion. In this sound-absorbing structure, since the first partition wall portion and the second partition wall portion are connected to each other at the end opposite to the top portion, while enabling the bending or flexing of the sound-absorbing structure, it is possible to suppress the enlargement of the sound-absorbing structure.

[0023] The tire according to the present disclosure includes any one of the above-described sound-absorbing structures attached to the inner cavity portion. In this tire, since it includes the above-described sound-absorbing structure, it is possible to reduce the resonance sound in the low-frequency range and easily make the thickness of the sound-absorbing structure thin. By making the thickness of the sound-absorbing structure thin, for example, it is possible to suppress the inhibition of the flow of the air current in the tire inner cavity portion by the sound-absorbing structure and suppress the decrease in the rotational balance of the tire by the sound-absorbing structure.

[0024] In the above-described tire, when the frequency of the tire cavity resonance sound is F, the speed of light is c, the radius of the inner cavity of the tire is R, the radius of the rim of the wheel assembled to the tire is r, and the pi is π, the sound absorbing structure may include a Helmholtz resonance structure in which Helmholtz resonance occurs at a resonance frequency within a range of ±100 Hz of the frequency of the tire cavity resonance sound calculated from F = c / ((R + r) × π). In this tire, since it has a Helmholtz resonance structure in which Helmholtz resonance occurs at a resonance frequency within a range of ±100 Hz of the frequency of the tire cavity resonance sound, the tire cavity resonance sound can be reduced.

Effect of the Invention

[0025] According to the present disclosure, it is possible to easily reduce the thickness while reducing the resonance sound in the low frequency range.

Brief Description of the Drawings

[0026]

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Figure 17

Mode for Carrying Out the Invention

[0027] Hereinafter, embodiments of the sound-absorbing structure according to the present disclosure will be described in detail with reference to the drawings. This embodiment is applied to a sound-absorbing structure for a tire that is attached to the inner cavity of a tire in order to reduce the resonance sound in the tire cavity. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and duplicate explanations are omitted.

[0028] (First Embodiment) Figure 1 is a schematic cross-sectional view of a tire to which the sound-absorbing structure according to the first embodiment is attached. In tire 101, cavity resonance may occur in which the internal air resonates when receiving vibrations when passing through the unevenness of the road surface during vehicle travel. The frequency of the sound due to cavity resonance is about 200 Hz to 300 Hz, typically about 250 Hz. The sound-absorbing structure 1 according to the present embodiment is attached to the inner cavity 102 of the tire 101 in order to efficiently absorb the low-frequency band sound due to cavity resonance. The inner cavity 102 is the inner peripheral surface of the tread 103.

[0029] Referring to FIGS. 2 and 3, the sound-absorbing structure 1 according to the first embodiment will be described. FIG. 2 is a schematic perspective view of the sound-absorbing structure according to the first embodiment. FIG. 3 is a schematic cross-sectional view taken along line III-III shown in FIG. 2. As shown in FIGS. 1 to 3, the sound-absorbing structure 1 according to the present embodiment is a thin sound-absorbing structure having a Helmholtz resonance structure. That the sound-absorbing structure 1 has a Helmholtz resonance structure means that the sound-absorbing structure 1 alone generates Helmholtz resonance, or that the sound-absorbing structure 1 generates Helmholtz resonance when attached to the inner cavity 102 of the tire 101. The sound-absorbing structure 1 includes an attachment surface 2 attached to the inner cavity 102 of the tire 101 and a top surface 3 arranged to face the attachment surface 2. An adhesive sheet 4 for attaching the sound-absorbing structure 1 to the inner cavity 102 of the tire 101 is attached to the attachment surface 2, for example.

[0030] The sound-absorbing structure 1 is formed in a rectangular strip shape. The direction in which the attachment surface 2 and the top surface 3 face each other is referred to as the thickness direction D1 of the sound-absorbing structure 1. As is clear from FIGS. 1 to 3, the thickness direction D1 of the sound-absorbing structure 1 is also the height direction (thickness direction) with respect to the attachment surface 2. Further, the thickness direction D1 of the sound-absorbing structure 1 is also the height direction (thickness direction) with respect to the inner cavity 102 when the sound-absorbing structure 1 is attached to the inner cavity 102 of the tire 101. The sound-absorbing structure 1 is formed in a rectangular shape in a plan view as seen from the thickness direction D1. Among the directions orthogonal to the thickness direction D1, the direction that is the longitudinal direction of the sound-absorbing structure 1 is referred to as the length direction D2, and the direction that is the short-side direction of the sound-absorbing structure 1 is referred to as the width direction D3. The thickness T2 of the sound-absorbing structure 1 is, for example, 20 mm or less. The thickness T2 is the dimension in the thickness direction D1. The width W1 of the sound-absorbing structure 1 is, for example, about 30 mm or more and 40 mm or less. The width W1 is the dimension in the width direction D3. The length of the sound-absorbing structure 1 is, for example, about 30 mm or more and 2000 mm or less. The length of the sound-absorbing structure 1 is the dimension in the length direction D2.

[0031] The sound-absorbing structure 1 is configured to include a box body 10 and a plurality of neck portions 20.

[0032] The housing 10 is a box-shaped member having a hollow portion 11 inside. The housing 10 forms the outer shape of the sound absorption structure 1. The housing 10 is also called the skin. The housing 10 has a plurality of openings 12 communicating with the hollow portion 11. The openings 12 penetrate the housing 10 and serve as inlets for the tire cavity resonance sound. The shape (cross-sectional shape) of the opening 12 is not particularly limited and can be various shapes such as circular, triangular, rectangular, polygonal, elliptical, etc. In this embodiment, it is a circular hole penetrating the housing 10. That is, the cross-sectional shape of the opening 12 is circular. The inner diameter of the opening 12 is, for example, about 1 mm to 5 mm. The number of the openings 12 in the housing 10 is not particularly limited.

[0033] The housing 10 is airtight. The housing 10 has at least one of a Shore A hardness of 40 or more and 100 or less and a Shore D hardness of 10 or more and 70 or less. In this case, the Shore A hardness of the housing 10 may be 50 or more and 80 or less, or may be 60 or more and 70 or less. Also, the Shore D hardness of the housing 10 may be 10 or more and 50 or less, or may be 10 or more and 40 or less.

[0034] The Shore A hardness of the housing 10 can be measured using a durometer in accordance with JIS K6253-3. For example, GS-709N TYPE A manufactured by Teclock Corporation can be used. The Shore D hardness of the housing 10 can be measured using a durometer in accordance with JIS K6253-3. For example, GS-720N TYPE D manufactured by Teclock Corporation can be used. When the allowable number of test piece laminations (3 or less) defined in JIS K6253-3 cannot satisfy the specified measurement thickness (6 mm or more), they can be stacked more than 3 sheets and measured at the regulated thickness.

[0035] The material of the housing 10 includes, for example, elastomers such as thermoplastic elastomers, plastics, rubbers, resins such as rubber-like materials, etc.

[0036] Examples of elastomer materials include thermoplastic elastomers such as styrene block copolymer (SBC), polyolefin (TPO), polyurethane (TPU), polyester (TPC), polyamide (TPA), dynamically crosslinked type (TPV), soft polyvinyl chloride (PVC), and acrylic.

[0037] Examples of plastic materials include polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polystyrene (PS), acrylonitrile butadiene styrene (ABS), polyphenylene sulfide (PPS), polyurethane (PU), epoxy resin, phenolic resin, and melamine resin.

[0038] Examples of rubber materials include natural rubber (NR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), ethylene propylene rubber (EPM), ethylene propylene diene rubber (EPDM), silicone rubber, and urethane rubber.

[0039] Examples of rubber-like materials include acrylic rubber-like materials having UV curability.

[0040] The box body 10 includes a top portion 13, a side portion 14, and a bottom portion 15. The wall thickness T1 of the box body 10 is, for example, about 0.1 mm to 2 mm. That is, the wall thickness T1 of each of the top portion 13, the side portion 14, and the bottom portion 15 is, for example, about 0.1 mm to 2 mm.

[0041] The top portion 13 is a portion that forms the top surface 3. The top portion 13 covers the upper part of the hollow portion 11. The upper part of the hollow portion 11 is one direction in the thickness direction D1. The top portion 13 is formed in a substantially rectangular shape in plan view as seen from the thickness direction D1.

[0042] The side portion 14 is a part that forms a part of the mounting surface 2. The side portion 14 is connected to the peripheral edge of the top portion 13 and extends in a direction intersecting the extending direction of the top portion 13. The extending direction of the top portion 13 is a direction along the length direction D2 and the width direction D3. Here, since the direction along the length direction D2 and the width direction D3 is a direction orthogonal to the thickness direction D1, the side portion 14 extends in a direction intersecting the direction orthogonal to the thickness direction D1. The direction intersecting the extending direction of the top portion 13 means, for example, a direction that does not coincide with the length direction D2 and the width direction D3 and is inclined at an angle greater than 0° with respect to the length direction D2 and the width direction D3. For example, the thickness direction D1 and the direction inclined with respect to the thickness direction D1 are also included in the direction intersecting the extending direction of the top portion 13.

[0043] The side portion 14 covers the side of the hollow portion 11. The side of the hollow portion 11 is a direction along the length direction D2 and the width direction D3. The side portion 14 extends from the peripheral edge of the top portion 13 to the mounting surface 2 over the entire circumference of the top portion 13. The cross-section orthogonal to the thickness direction D1 of the side portion 14 is formed in an endless rectangular ring shape. The side portion 14 has, for example, a tapered shape that narrows as it approaches the top portion 13. That is, the side portion 14 is inclined with respect to the thickness direction D1 so as to widen from the top portion 13 toward the mounting surface 2. The inclination angle θ of the side portion 14 with respect to the thickness direction D1 is, for example, about 0° or more and 50° or less.

[0044] The side portion 14 has a pair of long side portions 141 that extend in the length direction D2 facing the width direction D3, and a pair of short side portions 142 that extend in the width direction D3 facing the length direction D2. The pair of long side portions 141 and the pair of short side portions 142 are connected to each other at both their end edges.

[0045] A plurality of openings 12 penetrating the side portion 14 and communicating with the hollow portion 11 are formed in the side portion 14. In the present embodiment, the plurality of openings 12 are formed in one long side portion 141 and arranged in a line in the length direction D2. The long side portion 141 where the plurality of openings 12 are formed is referred to as an opening formation side portion 143. The opening ratio of the opening formation side portion 143 by the openings 12 (the ratio of the total area of the openings 12 to the area of the opening formation side portion 143 on the surface of the opening formation side portion 143) is, for example, about 0.1% to 10%.

[0046] The bottom portion 15 is a portion that forms a part of the mounting surface 2. The bottom portion 15 is connected to the side portion 14 and faces the top portion 13. The bottom portion 15 covers the lower side of the hollow portion 11. The lower side of the hollow portion 11 is the other direction in the thickness direction D1, that is, the direction opposite to the upper side of the hollow portion 11.

[0047] The neck portion 20 is a hollow member that communicates with the opening 12 and extends from the opening formation side portion 143 toward the hollow portion 11 side. The base end of the neck portion 20 is connected to the opening 12. The tip of the neck portion 20 is an open end where the hollow portion S of the neck portion 20 is exposed, and is located inside the hollow portion 11. The neck portion 20 is, for example, integrally formed with the box body 10. The number of the neck portions 20 is the same as the number of the openings 12, and each of the neck portions 20 is connected to each of the openings 12.

[0048] The neck portion 20 has airtightness similar to the box body 10. The neck portion 20 has at least one of the same Shore A hardness and Shore D hardness as the box body 10. The material of the neck portion 20 can be the same as the material of the box body 10.

[0049] The hollow portion S of the neck portion 20 has a cross-section that is the same as or larger than the cross-section of the opening 12. By increasing the extension length of the neck portion 20, the resonance frequency of the sound absorption structure 1 functioning as a Helmholtz resonator can be decreased. That is, by increasing the extension length of the neck portion 20, the resonance sound in the low frequency range can be reduced. The tip on the opening 12 side of the neck portion 20 is taken as the base end, and the tip on the side opposite to the opening 12 of the neck portion 20 is taken as the tip. The extension length of the neck portion 20 is the length of the extension axis of the neck portion 20 from the base end on the opening 12 side to the tip on the side opposite to the opening 12.

[0050] The shape of the neck portion 20 is not particularly limited. For example, the neck portion 20 may extend linearly in the width direction D3 from the opening 12. Here, since the width direction D3 is a direction orthogonal to the thickness direction D1, for the neck portion 20 to extend in the width direction D3 from the opening 12 means that the neck portion 20 extends in a direction orthogonal to the thickness direction D1 of the sound absorption structure 1, and for the neck portion 20 to extend linearly in the width direction D3 from the opening 12 means that the neck portion 20 extends linearly in a direction orthogonal to the thickness direction D1 of the sound absorption structure 1. Also, at least a part of the neck portion 20 may have a portion that intersects the width direction D3. To intersect the width direction D3 means that the extension direction of the neck portion 20 does not coincide with the width direction D3 and is inclined at an angle greater than 0° with respect to the width direction D3. That is, to intersect the width direction D3 means to be inclined to at least one of the thickness direction D1 and the length direction D2 with respect to the width direction D3. For example, the neck portion 20 may extend linearly in a direction inclined with respect to the width direction D3 from the base end to the tip, may extend while gently curving in a direction inclined with respect to the width direction D3 from the base end to the tip, or may extend in a spiral shape from the base end to the tip. Thus, by having a portion of the neck portion 20 that intersects the width direction D3 of the sound absorption structure 1, the neck portion 20 can be made longer than the width direction D3 of the sound absorption structure 1. Thereby, the tire inner cavity resonance sound in a lower frequency range can be reduced.

[0051] The sound-absorbing structure 1 configured as described above can be manufactured, for example, by injection molding, extrusion molding, 3D printing, the salt aggregation method, or the like.

[0052] As described above, in the sound-absorbing structure 1 according to the present embodiment, since it includes a box body 10 having an opening 12 and a hollow neck portion 20 communicating with the opening 12 and extending toward the hollow portion 11 side of the box body 10, the sound-absorbing structure 1 can function as a Helmholtz resonator, and by making the neck portion 20 longer, Helmholtz resonance of the resonance frequency in the low-frequency range can be generated. And since the opening 12 is formed in the side portion 14 of the box body 10, it is directed in a direction intersecting the thickness direction D1 of the sound-absorbing structure 1. For this reason, the neck portion 20 communicating with the opening 12 can also be easily extended in a direction intersecting the thickness direction D1 of the sound-absorbing structure 1. That is, the neck portion 20 can be made longer without making the sound-absorbing structure 1 thicker. For this reason, it is possible to reduce the thickness while reducing the resonance sound in the low-frequency range.

[0053] Also, since the side portion 14 extends in a direction intersecting the direction orthogonal to the thickness direction D1 of the sound-absorbing structure 1, it is possible to easily reduce the thickness of the sound-absorbing structure 1.

[0054] Also, since the neck portion 20 extends in a direction orthogonal to the thickness direction D1, it is possible to easily reduce the thickness of the sound-absorbing structure 1 while reducing the resonance sound in the low-frequency range.

[0055] Also, since the box body 10 has a top portion 13 and a side portion 14 connected to the peripheral edge of the top portion 13 and extending in a direction intersecting the extending direction of the top portion 13, the upper part of the hollow portion 11 can be covered with the top portion 13.

[0056] In addition, since the box body 10 has a bottom portion 15 connected to the side portion 14 and facing the top portion 13, the sound absorption structure 1 alone can function as a Helmholtz resonator. Therefore, for example, even if a gap is generated between the sound absorption structure 1 and the inner cavity portion 102 of the tire 101 which is the mounting target surface, the sound absorption structure 1 can function as a Helmholtz resonator.

[0057] In addition, since the opening 12 is a circular hole, the design as a Helmholtz resonator can be easily performed.

[0058] In addition, since the box body 10 has at least one of a Shore A hardness of 40 or more and 100 or less, 50 or more and 80 or less, or 60 or more and 70 or less and a Shore D hardness of 10 or more and 70 or less, 10 or more and 50 or less, or 10 or more and 40 or less, it is possible to enhance the followability with respect to the inner cavity portion 102 of the tire 101 which is the mounting target surface while suppressing deformation due to external forces such as centrifugal force and vibration.

[0059] In addition, since the box body 10 has an elastomer, it is possible to enhance the followability with respect to the inner cavity portion 102 of the tire 101 which is the mounting target surface while suppressing deformation due to external forces such as centrifugal force and vibration.

[0060] In the tire 101 according to the present embodiment, since the sound absorption structure 1 described above is provided, the resonance sound in the tire inner cavity can be reduced by the Helmholtz resonance generated in the hollow portion S of the neck portion 20. Moreover, since the opening 12 of the sound absorption structure 1 is formed in the side portion 14 of the box body 10, it is possible to easily reduce the thickness of the sound absorption structure 1 while reducing the resonance sound in the low frequency range. By reducing the thickness of the sound absorption structure 1, for example, it is possible to suppress the inhibition of the flow of the air flow in the inner cavity portion 102 of the tire 101 by the sound absorption structure 1 and to suppress the reduction of the rotational balance of the tire 101 by the sound absorption structure 1.

[0061] Here, as shown in FIG. 1, let the frequency of the tire cavity resonance sound be F, the speed of light be c, the radius of the inner cavity portion 102 of the tire 101 be R, the radius of the rim 105 of the wheel 104 assembled to the tire 101 be r, and the pi be π. In this case, the frequency of the tire cavity resonance sound is calculated by F = c / ((R + r) × π). The sound absorption structure 1 preferably includes a Helmholtz resonance structure in which Helmholtz resonance occurs at a resonance frequency within the range of ±100 Hz of the frequency of the tire cavity resonance sound calculated from F = c / ((R + r) × π).

[0062] The Helmholtz resonance structure is a structure including components of a Helmholtz resonator that resonates with the sound incident from the opening. In the sound absorption structure 1, the Helmholtz resonance structure is constituted by the box body 10 and the neck portion 20. That is, in the sound absorption structure 1, the airtight box body 10 extends to the mounting surface 2, and the hollow neck portion 20 communicates with the opening 12 of the box body 10. Therefore, in the hollow portion S of the neck portion 20, the Helmholtz resonance of the tire cavity resonance sound can be generated. And the resonance frequency of the sound absorption structure 1 functioning as a Helmholtz resonator changes depending on the extension length of the neck portion 20, the inner diameter of the opening 12, etc. For example, the larger the extension length of the neck portion 20 is, the lower the resonance frequency becomes. Also, the smaller the inner diameter of the opening 12 is, the lower the resonance frequency becomes. Further, the wider the distance between adjacent openings 12, the width W1 is, the larger the body volume of the Helmholtz resonator becomes, and the smaller the resonance frequency becomes. For this reason, it is preferable that the sound absorption structure 1 is adjusted such that Helmholtz resonance occurs at a resonance frequency within the range of ±100 Hz of the frequency of the tire cavity resonance sound calculated from F = c / ((R + r) × π).

[0063] In this way, by providing a Helmholtz resonance structure in which Helmholtz resonance occurs at a resonance frequency within the range of ±100 Hz of the frequency of the tire cavity resonance sound, the tire cavity resonance sound can be reduced.

[0064] FIG. 17 is a diagram showing a method for calculating the resonance frequency of a Helmholtz resonance structure. In the figure, the portions surrounded by broken lines each indicate a Helmholtz resonance structure unit. The resonance frequency of the Helmholtz resonance structure that resonates with the sound incident from each opening 12 can be adjusted from various dimensions of the hollow portion 11 according to this calculation method.

[0065] In FIG. 17, V is the volume of the hollow portion 11 when the hollow portion 11 is divided into Helmholtz resonance structure units. When the openings 12 are arranged in a lattice pattern with a constant period, that is, when the pitch P between the openings 12 is constant, V is calculated as the volume of a rectangular parallelepiped or cube obtained by multiplying the thickness T of the hollow portion 11 by a square or rectangle that starts from the center of adjacent openings 12 and passes through the midpoint between the openings 12. In the present embodiment, since the openings 12 are formed in the side portion 14 and the neck portion 20 extends from the side portion 14, the thickness T of the hollow portion 11 is the dimension in the direction perpendicular to the plane of FIG. 17. However, in FIG. 17, for the sake of convenience, the thickness T of the hollow portion 11 is illustrated as the dimension between the side portions 14. When there are a plurality of drawing methods for drawing a square passing through the midpoint between the openings 12, draw so that adjacent squares do not overlap and the area is maximized. Also, when the openings 12 are arranged randomly at unspecified pitch intervals without a constant period, that is, when the pitch P between the openings 12 is unspecified, V is calculated as the volume of a polygonal prism obtained by multiplying the thickness T of the hollow portion 11 by a polygon having the midpoint between adjacent openings 12 as vertices. In any case, when the neck portion 20 extends in the hollow portion 11, the volume V is the volume obtained by subtracting the volume of the neck portion 20. As shown in the third embodiment and the like described later, when a porous sound absorber is arranged in the hollow portion 11, V is the volume of the hollow portion 11 including the porous sound absorber. α is the area of the opening 12 when viewed from the thickness direction. δ is the end correction of the opening. For example, when the shape of the opening 12 is circular, δ can be calculated as 0.8 times the diameter of the opening 12. When the shape of the opening 12 is not circular, δ can be calculated as 0.8 times the diameter of a perfect circle having the same area as the area of the opening 12. L is the depth of the opening 12, that is, the extension length of the neck portion 20 (hollow portion).

[0066] (Second Embodiment) Referring to FIG. 4, the sound-absorbing structure 1A according to the second embodiment will be described. The second embodiment is basically the same as the first embodiment (refer to FIGS. 2 and 3), except that the box body has no bottom and has a flange portion. Therefore, below, only the matters different from the first embodiment will be described, and the description of the matters the same as the first embodiment will be omitted.

[0067] FIG. 4 is a schematic cross-sectional view of the sound-absorbing structure according to the second embodiment. As shown in FIG. 4, the box body 10A of the sound-absorbing structure 1A according to the present embodiment includes a top portion 13, a side portion 14, and a flange portion 16. Note that the box body 10A does not include a configuration corresponding to the bottom portion 15 of the sound-absorbing structure 1 according to the first embodiment.

[0068] The flange portion 16 is a portion that forms a part of the mounting surface 2. The flange portion 16 extends so as to spread from the peripheral edge portion on the side opposite to the top portion 13 of the side portion 14 along the mounting surface 2. The width W2 of the flange portion 16 is, for example, about 1 mm or more and 20 mm or less. The width W2 is a dimension in the direction away from the side portion 14.

[0069] In the sound-absorbing structure 1A, the hollow portion 11 is open downward, and the mounting surface 2 is formed by the end surface on the side opposite to the top portion 13 of the side portion 14 and the flange portion 16.

[0070] As described above, the sound absorption structure 1A according to the present embodiment does not include a configuration corresponding to the bottom portion 15 of the sound absorption structure 1 according to the first embodiment. However, since the box body 10A includes a top portion 13 and side portions 14 connected to the peripheral edge of the top portion 13 and extending in a direction intersecting the extending direction of the top portion 13, the sound absorption structure 1A attached to the inner cavity portion 102 of the tire 101, which is the mounting target surface, can function as a Helmholtz resonator. That is, the end surface of the side portion 14 opposite to the top portion 13 forms the mounting surface 2, and when this mounting surface 2 is attached to the inner cavity portion 102 of the tire 101, which is the mounting target surface, the only portion where the hollow portion 11 is opened is the opening 12. Therefore, the sound absorption structure 1A functions as a Helmholtz resonator.

[0071] Further, in this sound absorption structure 1A, although it does not include a configuration corresponding to the bottom portion 15 of the sound absorption structure 1 according to the first embodiment, since the box body 10A includes a flange portion 16, the sound absorption structure 1A can be easily attached to the inner cavity portion 102 of the tire 101, which is the mounting target surface.

[0072] (Third Embodiment) With reference to FIG. 5, the sound absorption structure 1B according to the third embodiment will be described. The third embodiment is basically the same as the first embodiment (see FIGS. 2 and 3), and is different from the first embodiment only in that it further includes a porous sound absorber. Therefore, hereinafter, only the matters different from the first embodiment will be described, and the description of the matters the same as the first embodiment will be omitted.

[0073] FIG. 5 is a schematic cross-sectional view of the sound absorption structure according to the third embodiment. As shown in FIG. 5, the sound absorption structure 1B according to the present embodiment includes a box body 10, a plurality of neck portions 20, and a porous sound absorber 30.

[0074] The porous sound absorber 30 is disposed in the hollow portion 11 of the box body 10. The neck portions 20 are in a state of being embedded in the porous sound absorber 30. The tips of the neck portions 20 are located within the porous sound absorber 30.

[0075] The porous sound absorber 30 is formed, for example, by foam molding of a resin material such as plastic or rubber. Examples of the plastic material include foamed polyurethane. Either rigid foamed polyurethane or soft foamed polyurethane may be used. As the manufacturing method of foamed polyurethane, a general method can be used. For example, by mixing a polyol and a polyisocyanate with a foaming agent, a foam stabilizer, a catalyst, etc., filling the mixture into a mold, and foaming and curing it, the porous sound absorber 30 can be obtained.

[0076] Examples of the rubber material include rubber materials obtained from latex such as natural rubber (NR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), and chloroprene rubber (CR). By foaming and solidifying these rubber materials, the porous sound absorber 30 can be obtained.

[0077] The pore diameter of the porous sound absorber 30 is, for example, 1 μm or less, preferably 500 μm or less. The open porosity of the porous sound absorber 30 (the ratio of the total area of the pores to the area of the porous sound absorber on the surface of the porous sound absorber 30) is, for example, about 65% to 99%, preferably about 80% to 95%. The pore diameter and the open porosity can be measured, for example, using a computed tomography (CT scan) apparatus using X-rays. For calculating the pore diameter, the average value of the diameters of a plurality (for example, 100) of pores extracted based on the observation image can be used. For calculating the open porosity, the division value obtained by dividing the total area of all the pores extracted based on the observation image by the area of the porous sound absorber can be used.

[0078] As described above, in the sound absorption structure 1B according to the present embodiment, since the porous sound absorber 30 is provided, the sound in the high-frequency range can be reduced.

[0079] (Fourth Embodiment) Referring to FIG. 6, the sound absorption structure 1C according to the fourth embodiment will be described. The fourth embodiment is basically the same as the first embodiment (see FIGS. 2 and 3), except that the neck portion has a fixing portion. Therefore, below, only the matters different from the first embodiment will be described, and the description of the matters the same as the first embodiment will be omitted.

[0080] FIG. 6 is a schematic cross-sectional view of the sound absorption structure according to the fourth embodiment. As shown in FIG. 6, the sound absorption structure 1C according to the present embodiment includes a box body 10 and a plurality of neck portions 20C.

[0081] The neck portion 20C has a fixing portion 21C fixed to the box body 10 at a position at least separated from the opening 12. The neck portion 20C is the same as the neck portion 20 of the first embodiment except for having the fixing portion 21C. The position of the fixing portion 21C in the neck portion 20C is not particularly limited, and may be the tip of the neck portion 20C, the central portion in the extending direction of the neck portion 20C, or the entire region in the extending direction of the neck portion 20C. Also, the position of the box body 10 to which the fixing portion 21C is fixed is not particularly limited, and may be the top portion 13, the side portion 14, or the bottom portion 15. In the present embodiment, the entire region in the extending direction of the neck portion 20C serves as the fixing portion 21C fixed to the bottom portion 15. Further, since the neck portion 20C extends along the bottom portion 15 in a direction parallel to the width direction D3 and the length direction D2, and the tip of the neck portion 20C is directed in a direction parallel to the width direction D3 and the length direction D2, the hollow portion S of the neck portion 20C serves as an open end exposed to the hollow portion 11. The fixing of the fixing portion 21C to the box body 10C can be performed, for example, by integral molding, adhesion, welding, or the like.

[0082] As described above, in the sound absorption structure 1C according to the present embodiment, since the neck portion 20C has a fixing portion 21C fixed to the box body 10 at a position at least separated from the opening 12, the movement of the neck portion 20C with respect to the box body 10 can be suppressed. For this reason, for example, when an external force such as centrifugal force or vibration acts on the sound absorption structure 1C, it is possible to suppress the excessive displacement of the neck portion 20C with respect to the box body 10.

[0083] (Fifth Embodiment) With reference to FIG. 7, the sound absorption structure 1D according to the fifth embodiment will be described. The fifth embodiment is basically the same as the first embodiment (see FIGS. 2 and 3), except that the hollow portion of the box body is partitioned. For this reason, below, only the matters different from the first embodiment will be described, and the description of the same matters as the first embodiment will be omitted.

[0084] FIG. 7 is a schematic cross-sectional view of the sound absorption structure according to the fifth embodiment. In FIG. 7, the illustration of the neck portion is omitted. As shown in FIG. 7, the sound absorption structure 1D according to the present embodiment includes a box body 10D and a plurality of neck portions 20 (see FIG. 3). The box body 10D includes a top portion 13, a side portion 14, a bottom portion 15, and a plurality of partition walls 17.

[0085] Each of the plurality of partition walls 17 is a part that is connected to the top portion 13, the side portion 14, and the bottom portion 15 and divides the hollow portion 11 into two small spaces 11a. Each of the plurality of partition walls 17 divides the hollow portion 11, for example, in the length direction D2. When four partition walls 17 are provided as shown in FIG. 7, the hollow portion 11 is divided into five small spaces 11a by the four partition walls 17. The partition wall 17 is connected to the top portion 13, the side portion 14, and the bottom portion 15 so that the two divided small spaces 11a do not communicate with each other. For this reason, the two small spaces 11a divided by the partition wall 17 are independent spaces from each other. Further, each of the plurality of partition walls 17 divides the hollow portion 11 so that at least one opening 12 communicates with each of the partitioned small spaces 11a. In this case, each of the plurality of partition walls 17 may divide the hollow portion 11 so that one opening 12 communicates with each of the partitioned small spaces 11a. The partition wall 17 is formed, for example, in a flat plate shape extending along the thickness direction D1 and the width direction D3.

[0086] As described above, in this sound absorption structure 1D, the hollow portion 11 of the box body 10D is divided into two small spaces 11a by the partition wall 17, and at least one opening 12 communicates with each of the two small spaces 11a. Therefore, while each of the two small spaces 11a functions as a Helmholtz resonator, the rigidity of the sound absorption structure 1D can be increased.

[0087] Further, since one opening 12 communicates with each of the two small spaces 11a, the sound absorption structure 1D can be divided into Helmholtz resonator units.

[0088] (Sixth Embodiment) With reference to FIGS. 8 and 9, the sound absorption structure 1E according to the sixth embodiment will be described. The sixth embodiment is basically the same as the fifth embodiment (see FIG. 7), and differs from the fifth embodiment only in that the configurations of the partition wall, the top portion, and the side portion are different. For this reason, hereinafter, only the matters different from the fifth embodiment will be described, and the description of the matters the same as the fifth embodiment will be omitted.

[0089] FIG. 8 is a schematic perspective view of a sound absorption structure according to the sixth embodiment. FIG. 9 is a schematic cross-sectional view taken along line IX-IX shown in FIG. 8. Note that in FIG. 9, illustration of the neck portion is omitted. As shown in FIGS. 8 and 9, the sound absorption structure 1E according to the present embodiment includes a box body 10E and a plurality of neck portions 20 (see FIG. 3). The box body 10E includes a top portion 13E, side portions 14E, a bottom portion 15, and a plurality of partition walls 17E.

[0090] Each of the plurality of partition walls 17E has a first partition wall portion 17a and a second partition wall portion 17b. The first partition wall portion 17a is a portion located on one side of two small spaces 11a partitioned by each of the plurality of partition walls 17E, and the second partition wall portion 17b is a portion located on the other side of two small spaces 11a partitioned by each of the plurality of partition walls 17E.

[0091] The top portion 13E and the side portions 14E are divided by the first partition wall portion 17a and the second partition wall portion 17b. That is, the top portion 13E is divided into a plurality of small top portions 13a by the first partition wall portion 17a and the second partition wall portion 17b that constitute each of the plurality of partition walls 17E. Also, the side portions 14E are divided into a plurality of small side portions 14a by the first partition wall portion 17a and the second partition wall portion 17b that constitute each of the plurality of partition walls 17E. Note that the bottom portion 15 is not divided by the first partition wall portion 17a and the second partition wall portion 17b.

[0092] The first partition wall portion 17a and the second partition wall portion 17b are arranged in a V shape such that the distance between them increases as they go toward the top portion 13E. And when the portion of the bottom portion 15 that forms the small space 11a is defined as the bottom portion 15a, the length of the small top portion 13a in the length direction D2 is shorter than the length of the bottom portion 15a in the length direction D2. The first partition wall portion 17a and the second partition wall portion 17b may be separated from each other, or may be connected to each other at the end opposite to the top portion 13E. That is, the first partition wall portion 17a and the second partition wall portion 17b may be indirectly connected via the bottom portion 15, or may be directly connected.

[0093] As described above, in this sound absorption structure 1E, the top portion 13E and the side portions 14E are divided by the first partition wall portion 17a and the second partition wall portion 17b, making the sound absorption structure 1E easier to bend or flex. Thereby, the followability with respect to the inner cavity portion 102 of the tire 101, which is the mounting target surface, can be further enhanced.

[0094] Further, since the first partition wall portion 17a and the second partition wall portion 17b are arranged such that the distance between them increases as they approach the top portion 13E, the sound absorption structure 1E can be easily bent or flexed with the top portion 13E side on the inner side.

[0095] Moreover, since the length of the small top portion 13a in the length direction D2 is shorter than the length of the bottom portion 15a in the length direction D2, the sound absorption structure 1E can be easily bent or flexed with the top portion 13E side on the inner side.

[0096] Further, since the first partition wall portion 17a and the second partition wall portion 17b are connected to each other at the end opposite to the top portion 13E, while enabling the sound absorption structure 1E to be bent or flexed, it is possible to suppress the sound absorption structure 1E from becoming larger in size.

[0097] (Seventh Embodiment) With reference to FIGS. 10 to 12, the sound absorption structure 1F according to the seventh embodiment will be described. The seventh embodiment is basically the same as the first embodiment (see FIGS. 2 and 3), and differs from the first embodiment only in that the shape of the opening is different. Therefore, hereinafter, only the matters different from the first embodiment will be described, and the description of the matters the same as the first embodiment will be omitted.

[0098] FIG. 10 is a schematic perspective view of the sound absorption structure according to the seventh embodiment. FIG. 11 is a schematic cross-sectional view taken along line XI-XI shown in FIG. 10. FIG. 12 is a schematic cross-sectional view taken along line XII-XII shown in FIG. 10. As shown in FIGS. 10 to 12, the sound absorption structure 1F according to the present embodiment includes a box body 10F and a plurality of neck portions 20F.

[0099] The box body 10F includes a top portion 13, side portions 14F, and a bottom portion 15. A plurality of openings 12F communicating with the hollow portion 11 of the box body 10F are formed in the side portions 14F. The side portions 14F are the same as the side portions 14 of the first embodiment, except that the openings 12F are formed instead of the openings 12. The side portions 14F have a pair of long side portions 141F and a pair of short side portions 142F corresponding to the pair of long side portions 141 and the pair of short side portions 142 of the first embodiment. The plurality of openings 12F are formed in one of the long side portions 141F and are arranged in the length direction D2. The long side portion 141F in which the plurality of openings 12F are formed is referred to as an opening-forming side portion 143F.

[0100] The opening 12F is a slit extending linearly and penetrates the opening-forming side portion 143F. The slit that is the opening 12F extends linearly in the thickness direction D1 over the entire region in the thickness direction D1 of the opening-forming side portion 143F.

[0101] The neck portion 20F communicates with the slit that is the opening 12F and extends from the opening-forming side portion 143F toward the hollow portion 11 side. The neck portion 20F is the same as the neck portion 20 of the first embodiment, except that it communicates with the slit that is the opening 12F.

[0102] The shape of the neck portion 20F is not particularly limited. For example, the neck portion 20F may extend linearly in the width direction D3 from the opening 12F. Also, the neck portion 20F may extend in a bent or curved manner. Further, at least a part of the neck portion 20F may have a portion intersecting the width direction D3. For example, the neck portion 20F may extend linearly in the width direction D3 from the opening 12F and then be bent or curved in an L-shape or a J-shape and extend linearly in the length direction D2.

[0103] The sound-absorbing structure 1F configured as described above can be manufactured, for example, by injection molding, extrusion molding, shaping by a 3D printer, the salt aggregation method, or the like. For example, since the slit that is the opening 12F linearly extends in the thickness direction D1 over the entire area in the thickness direction D1 of the opening formation side portion 143F, the sound-absorbing structure 1F excluding the top portion 13, the bottom portion 15, and the long side portion 141F facing the opening formation side portion 143F can be produced by extrusion molding. Thereafter, the sound-absorbing structure 1F can be manufactured by joining the separately manufactured top portion 13, bottom portion 15, and long side portion 141F facing the opening formation side portion 143F to the sound-absorbing structure 1F excluding the top portion 13, bottom portion 15, and long side portion 141F facing the opening formation side portion 143F. Further, a structure having the same cross section as the sound-absorbing structure 1F excluding the top portion 13, bottom portion 15, and long side portion 141F facing the opening formation side portion 143F is continuously extruded in the thickness direction D1, the extruded structure is cut at a predetermined length dimension in the thickness direction D1, and the separately manufactured top portion 13, bottom portion 15, and long side portion 141F facing the opening formation side portion 143F are joined to the cut structure, whereby the sound-absorbing structure 1F can also be manufactured.

[0104] As described above, in this sound-absorbing structure 1F, since the opening 12F is a slit that linearly extends, the sound-absorbing structure 1F can be easily manufactured.

[0105] (Eighth Embodiment) With reference to FIGS. 13 and 14, the sound-absorbing structure 1G according to the eighth embodiment will be described. The eighth embodiment is basically the same as the seventh embodiment (see FIGS. 10 to 12), and is different from the seventh embodiment only in that the extending direction of the slit that is the opening is different. For this reason, hereinafter, only matters different from the seventh embodiment will be described, and the description of matters the same as those of the seventh embodiment will be omitted.

[0106] FIG. 13 is a schematic perspective view of the sound-absorbing structure according to the eighth embodiment. FIG. 14 is a schematic cross-sectional view taken along line XIV-XIV shown in FIG. 13. As shown in FIGS. 13 and 14, the sound-absorbing structure 1G according to the present embodiment includes a box body 10G and one neck portion 20G.

[0107] The box body 10G includes a top portion 13, side portions 14G, and a bottom portion 15. One opening 12G that communicates with the hollow portion 11 of the box body 10G is formed in the side portion 14G. The side portion 14G is the same as the side portion 14F of the seventh embodiment, except that the opening 12G is formed instead of the opening 12F. The side portion 14G has a pair of long side portions 141G and a pair of short side portions 142G corresponding to the pair of long side portions 141F and the pair of short side portions 142F of the seventh embodiment. The opening 12G is formed in one of the long side portions 141G. The long side portion 141G in which the opening 12G is formed is referred to as an opening-forming side portion 143G.

[0108] The opening 12G is a linearly extending slit that penetrates the opening-forming side portion 143G. The slit that is the opening 12G linearly extends in the length direction D2 over the entire region in the length direction D2 of the opening-forming side portion 143G.

[0109] The neck portion 20G communicates with the slit that is the opening 12G and extends from the opening-forming side portion 143G toward the hollow portion 11 side. The neck portion 20G is the same as the neck portion 20F of the seventh embodiment, except that it communicates with the slit that is the opening 12G.

[0110] The sound-absorbing structure 1G configured in this way can be manufactured by, for example, injection molding, extrusion molding, shaping by a 3D printer, the salt aggregation method, or the like. For example, since the slit that is the opening 12G linearly extends in the length direction D2 over the entire region in the length direction D2 of the opening-forming side portion 143G, the sound-absorbing structure 1G excluding the pair of short side portions 142G can be produced by extrusion molding. Thereafter, the sound-absorbing structure 1G can be manufactured by joining the pair of short side portions 142G separately produced to the sound-absorbing structure 1G excluding the pair of short side portions 142G. Also, a structure having the same cross-section as the sound-absorbing structure 1G excluding the pair of short side portions 142G is continuously extruded in the length direction D2, the extruded structure is cut at a predetermined length dimension in the length direction D2, and the pair of short side portions 142G separately produced are joined to the cut structure, whereby the sound-absorbing structure 1G can also be manufactured.

[0111] (Ninth Embodiment) With reference to FIG. 15, the sound-absorbing structure 1H according to the ninth embodiment will be described. The ninth embodiment is basically the same as the sixth embodiment (see FIGS. 8 and 9), and is different from the sixth embodiment only in that the opening has the same shape as that of the seventh embodiment. For this reason, below, only matters different from the sixth embodiment will be described, and description of matters the same as those of the sixth embodiment will be omitted.

[0112] FIG. 15 is a schematic perspective view of the sound-absorbing structure according to the ninth embodiment. As shown in FIG. 15, the sound-absorbing structure 1H according to the present embodiment includes a box body 10H and a plurality of neck portions 20F (see FIGS. 11 and 12) similar to those of the seventh embodiment. The box body 10H includes a top portion 13E, a side portion 14H, a bottom portion 15, and a plurality of partition walls 17E (see FIGS. 8 and 9). Each of the plurality of partition walls 17E has a first partition wall portion 17a and a second partition wall portion 17b.

[0113] A plurality of openings 12H are formed in the side portion 14H. The openings 12H are slits extending linearly, similar to those of the seventh embodiment, and extend linearly in the thickness direction D1 over the entire region in the thickness direction D1 of the side portion 14H. The neck portion 20F communicates with the slit that is the opening 12H and extends from the side portion 14H toward the hollow portion 11 side.

[0114] The present disclosure is not limited to the above-described embodiments, and can be appropriately changed without departing from the gist of the present disclosure.

[0115] For example, when including a plurality of openings and neck portions, the frequencies of Helmholtz resonance generated by at least two neck portions may be different from each other. By the frequencies of Helmholtz resonance generated by at least two neck portions being different from each other, the resonance sound in the tire inner cavity can be reduced in a wide frequency band.

[0116] Further, for example, the sound absorption structure may be formed in a flat plate shape or a curved shape. For example, like the sound absorption structure 1I shown in FIG. 16, the sound absorption structure may be formed in a shape that is curved in an arc shape along the inner cavity of the tire. FIG. 16 is a schematic side view showing a sound absorption structure of a modified example. In this way, since the sound absorption structure is curved in an arc shape, the ease of attachment to the inner cavity of the tire is improved.

[0117] Further, for example, when attaching a plurality of sound absorption structures to a tire, two or more sound absorption structures that generate Helmholtz resonances with different resonance frequencies may be attached to the tire.

[0118] Further, for example, a hollow outer neck portion that communicates with an opening formed in the box body and extends to the outside of the box body (opposite side to the hollow portion) may be further provided so that the neck portion extends to the outside of the box body. In this case, the resonance frequency of the sound absorption structure can be adjusted by the total length of the neck portion and the outer neck portion.

[0119] Further, for example, in the above-described embodiment, the sound absorption structure has been described as a sound absorption structure for a tire that is attached to the inner cavity of the tire in order to reduce the resonance sound in the tire inner cavity. However, the use of the sound absorption structure is not particularly limited.

[0120] Further, for example, in the above-described embodiment, the box body has been described as including a top portion, a side portion, and a bottom portion. However, the box body may have any shape and structure as long as it includes a side portion in which an opening is formed. That is, as long as the box body includes a side portion in which an opening is formed, the box body can be easily made thin while reducing the resonance sound in the low frequency range regardless of its shape and structure. For this reason, the box body may be formed, for example, in a shape that extends in a cylindrical shape. When the box body is formed in a shape that extends in a cylindrical shape, for example, an opening that communicates with the neck portion is formed in at least one of the opposing both ends, and at least one of these both ends may be attached to the inner cavity of the tire or the like so as to be the side portion of the box body.

[0121] The gist of the present disclosure is as follows in [1] to

[18] . [1] A sound absorption structure including a box body having an opening and a hollow neck portion communicating with the opening and extending toward the hollow portion side of the box body, wherein the opening is formed in a side portion of the box body. [2] The sound absorption structure according to [1], wherein the side portion extends in a direction intersecting with a direction orthogonal to the thickness direction of the sound absorption structure. [3] The sound absorption structure according to [1] or [2], wherein the neck portion extends in a direction orthogonal to the thickness direction. [4] The sound absorption structure according to any one of [1] to [3], wherein the neck portion has a fixing portion fixed to the box body at least at a position separated from the opening. [5] The sound absorption structure according to any one of [1] to [4], wherein the opening is a circular hole. [6] The sound absorption structure according to any one of [1] to [5], wherein the opening is a linearly extending slit. [7] The sound absorption structure according to any one of [1] to [6], further including a porous sound absorber accommodated in the hollow portion of the box body. [8] The sound absorption structure according to any one of [1] to [7], wherein the box body has at least one of a Shore A hardness of 80 or more and 100 or less and a Shore D hardness of 30 or more and 70 or less. [9] The sound absorption structure according to any one of [1] to [8], wherein the box body has an elastomer.

[10] The sound absorption structure according to any one of [1] to [9], wherein the box body has a top portion, and the side portion is connected to a peripheral edge portion of the top portion and extends in a direction intersecting with an extending direction of the top portion.

[11] The sound absorption structure according to

[10] , wherein the box body further has a bottom portion connected to the side portion and facing the top portion.

[12] The sound absorption structure according to

[11] or

[12] , wherein the box body has a plurality of the openings and a partition wall connected to the top portion and the side portion and partitioning the hollow portion into two small spaces, and the partition wall partitions the hollow portion such that at least one of the openings communicates with each of the two small spaces.

[13] The partition wall is the sound absorption structure according to

[12] , which divides the hollow portion such that one of the openings communicates with each of the two small spaces.

[14] The partition wall has a first partition wall portion located on one side of the two small spaces and a second partition wall portion located on the other side of the two small spaces, and the top portion and the side portion are divided by the first partition wall portion and the second partition wall portion. The sound absorption structure according to

[12] or

[13] .

[15] The first partition wall portion and the second partition wall portion are arranged such that the distance between them increases as they approach the top portion. The sound absorption structure according to

[14] .

[16] The first partition wall portion and the second partition wall portion are connected to each other at the ends on the side opposite to the top portion. The sound absorption structure according to

[14] or

[15] .

[17] A tire comprising the sound absorption structure according to any one of [1] to

[16] attached to the inner cavity portion.

[18] When the frequency of the tire inner cavity resonance sound is F, the speed of light is c, the radius of the inner cavity portion of the tire is R, the radius of the rim of the wheel assembled to the tire is r, and the pi is π, the sound absorption structure has a Helmholtz resonance structure in which Helmholtz resonance occurs at a resonance frequency within a range of ±100 Hz of the frequency of the tire inner cavity resonance sound calculated from F = c / ((R + r) × π). The tire according to

[17] .

Explanation of symbols

[0122] 1…Sound absorption structure, 1A…Sound absorption structure, 1B…Sound absorption structure, 1C…Sound absorption structure, 1D…Sound absorption structure, 1E…Sound absorption structure, 1F…Sound absorption structure, 1G…Sound absorption structure, 1H…Sound absorption structure, 1I…Sound absorption structure, 2…Mounting surface, 3…Ceiling surface, 4…Adhesive sheet, 10…Cabinet, 10A…Cabinet, 10C…Cabinet, 10D…Cabinet, 10E…Cabinet, 10F…Cabinet, 10G…Cabinet, 10H…Cabinet, 11…Hollow part, 11a…Small space, 12…Opening, 12F…Opening, 12G…Opening, 12H…Opening, 13…Top part, 13a…Small top part, 13E…Top part, 14…Side part, 141…Long side part, 142…Short side part, 143…Opening-forming side part, 14a…Small side part, 14E…Side part, 14F…Side part, 141F…Long side part, 142F…Short side part, 143F…Opening-forming side part, 14G…Side part, 141G…Long side part, 142G…Short side part, 143G…Opening-forming side part, 14H…Side part, 15…Bottom part, 15a…Bottom part, 16…Flange part, 17…Partition wall, 17a…First partition wall part, 17b…Second partition wall part, 17E…Partition wall, 20…Neck part, 20C…Neck part, 20F…Neck part, 20G…Neck part, 21C…Fixing part, 30…Porous sound absorber, 101…Tire, 102…Inner cavity part, 103…Tread, 104…Wheel, 105…Rim, D1…Thickness direction, D2…Length direction, D3…Width direction, S…Hollow part.

Claims

1. A box having an opening; a hollow neck portion communicating with the opening and extending toward a hollow portion of the box body, The opening is formed in a side portion of the box body, The box body has a bottom portion disposed on a side of a target surface to which the sound absorbing structure is to be attached, and a top portion opposed to the bottom portion, The neck portion is spaced from the top portion and extends along and in contact with the bottom portion. Sound absorbing structure.

2. The neck portion is disposed on the base portion.

2. The sound absorbing structure according to claim 1.

3. The side portion extends in a direction intersecting a direction perpendicular to a thickness direction of the sound absorbing structure.

2. The sound absorbing structure according to claim 1.

4. The neck portion extends in a direction perpendicular to a thickness direction of the sound absorbing structure.

2. The sound absorbing structure according to claim 1.

5. The neck portion has a fixing portion fixed to the box body at least at a position spaced from the opening.

2. The sound absorbing structure according to claim 1.

6. The opening is a circular hole.

2. The sound absorbing structure according to claim 1.

7. The opening is a linearly extending slit.

2. The sound absorbing structure according to claim 1.

8. The sound absorbing device further includes a porous sound absorbing body accommodated in the hollow portion of the box body. The sound absorbing structure according to claim 1 .

9. The box has at least one of a Shore A hardness of 40 or more and 100 or less and a Shore D hardness of 10 or more and 70 or less. The sound absorbing structure according to claim 1 .

10. The box includes an elastomer.

2. The sound absorbing structure according to claim 1.

11. The side portion is connected to the peripheral portion of the top portion and extends in a direction intersecting the extension direction of the top portion. The sound absorbing structure according to claim 1 .

12. The box body has a plurality of the openings and a partition wall connected to the top portion and the side portion to divide the hollow portion into two small spaces, The partition wall divides the hollow portion such that at least one of the openings communicates with each of the two small spaces.

12. A sound absorbing structure according to claim 11.

13. The partition wall divides the hollow portion such that one of the openings communicates with each of the two small spaces.

13. A sound absorbing structure as claimed in claim 12.

14. The partition wall has a first partition wall portion located on one side of the two small spaces and a second partition wall portion located on the other side of the two small spaces, The top portion and the side portion are divided by the first partition wall portion and the second partition wall portion.

13. A sound absorbing structure as claimed in claim 12.

15. The first partition wall portion and the second partition wall portion are disposed such that a distance therebetween increases toward the top portion.

15. A sound absorbing structure as claimed in claim 14.

16. The first partition wall portion and the second partition wall portion are connected to each other at an end portion opposite to the top portion.

15. A sound absorbing structure as claimed in claim 14.

17. The box body is formed in a cylindrical shape. The sound absorbing structure according to claim 1 .

18. The side portion is at least one of both ends of the cylindrically extending box body, 18. A sound absorbing structure as claimed in claim 17.

19. The neck portion extends in the hollow portion a length equal to or greater than half of the length of the hollow portion in the direction of extension of the neck portion. The sound absorbing structure according to claim 1 .

20. The sound absorbing structure according to any one of claims 1 to 19 is attached to an inner cavity. tire.

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