Resonance sound absorber

Abstract

This resonance sound absorber comprises a resonance box having a hollow part in the interior thereof and also having a first opening where the hollow part is open to the outside. The resonance box has a box body that has a second opening and a lid part that covers the second opening. A lid engagement part provided to the lid part is made to engage with a box engagement part provided to the box body, whereby the lid part is attached to the box body so as to cover the second opening.

Description

Resonant sound absorber

[0001] The present disclosure relates to a resonant sound absorber.

[0002] BACKGROUND ART Conventionally, a resonance sound absorber that reduces tire cavity resonance noise generated when a vehicle is running by Helmholtz resonance has been known (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2021-067767

[0004] Such a resonant sound absorber includes a resonance box with a hollow space inside. To create the resonance box, a conceivable approach would be to glue together a box body with an open side and a hollow space inside, and a lid that covers the open side of the box body. However, it can be difficult to glue the box body and the lid together without allowing air to leak, and it is also difficult to confirm whether they are properly glued together.

[0005] Therefore, the present disclosure describes a resonant sound absorber that can easily form a resonance box.

[0006] The resonant sound absorber of the present disclosure is a resonant sound absorber attached to the inner cavity surface of a tire, and includes a resonance box having a hollow portion inside and a first opening that opens the hollow portion to the outside, and the resonance box has a box main body portion having a hollow portion inside and a second opening that opens the hollow portion to the outside, and a lid portion that covers the second opening, the first opening being provided on the box main body portion or the lid portion, and the lid portion is attached to the box main body portion so as to cover the second opening by engaging a lid engaging portion provided on the lid portion with a box engaging portion provided on the box main body portion.

[0007] In this resonance sound absorber, the lid is attached to the box body by engaging a box engaging portion provided on the box body with a lid engaging portion provided on the lid. In this way, by engaging the box engaging portion with the lid engaging portion, a resonance box with a hollow portion inside can be easily formed.

[0008] In the above-described resonance sound absorber, the box main body has a second opening and a main body mounting portion to which the lid is attached, the main body mounting portion being tubular and having one end with the second opening, the main body outer peripheral surface being cylindrical, the lid has a lid sealing portion that seals the second opening and a lid mounting portion that surrounds the main body mounting portion from the outside, the lid inner peripheral surface being cylindrical, the box engaging portion being provided on the main body outer peripheral surface, and the lid engaging portion being provided on the lid inner peripheral surface, the box engaging portion and the lid engaging portion being engaged with each other by rotating the lid relative to the main body mounting portion with the lid placed on the main body mounting portion. In this resonance sound absorber, the main body outer peripheral surface of the main body mounting portion of the box main body and the lid inner peripheral surface of the lid are cylindrical. In other words, the lid can be rotated relative to the main body mounting portion with the lid placed on the main body mounting portion of the box main body. In the resonance sound absorber, the lid is rotated relative to the main body mounting portion, thereby engaging the box engaging portion and the lid engaging portion. In this way, in the resonance sound absorber, the lid can be easily attached to the box main body by rotating the lid relative to the main body mounting portion.

[0009] In the above-mentioned resonance sound absorber, the box engagement portion may be constituted by a box protrusion protruding from the outer peripheral surface of the main body, and the lid engagement portion may be constituted by a lid engagement groove provided on the inner peripheral surface of the lid and into which the box protrusion is fitted. In this resonance sound absorber, the box main body and the lid can be more reliably engaged by engaging the box protrusion provided on the box engagement portion with the lid engagement groove provided on the lid.

[0010] In the above-described resonant sound absorber, the lid engagement groove may have a groove accommodating portion that accommodates the box protrusion when the second opening is sealed by the lid sealing portion, and a lid protrusion may be provided on the wall surface of the lid engagement groove to prevent the box protrusion accommodated in the groove accommodating portion from slipping out of the groove accommodating portion. In this case, when the lid is attached to the box main body, the lid is prevented from coming off the box main body.

[0011] In the above-described resonance sound absorber, the box main body may include an outer wall having a cylindrical tubular portion with an inner hollow portion and a sealing wall portion that closes an opening at one end of the tubular portion, and the second opening may be provided at the end of the tubular portion opposite the end where the sealing wall portion is provided. Having the cylindrical tubular portion in the box main body can prevent stress from concentrating at a single point on the tubular portion even when the sound pressure inside the tire cavity changes. Thus, the cylindrical tubular portion in the resonance sound absorber can ensure the rigidity of the box main body.

[0012] In the above-described resonant sound absorber, the first opening may be provided in the sealing wall portion. In this case, the resonant sound absorber can take sound (air vibrations) into the hollow portion of the resonance box through the first opening provided in the sealing wall portion of the box main body.

[0013] In the above-described resonance sound absorber, the box main body may include a hollow neck portion that connects the first opening and the hollow portion. In this resonance sound absorber, the resonance box includes a hollow neck portion that connects the first opening and the hollow portion, and therefore the resonant frequency of Helmholtz resonance can be adjusted by adjusting the length of the neck portion. Furthermore, by lengthening the neck portion, Helmholtz resonance with a resonant frequency in the low-frequency range can be generated. Therefore, the resonance sound absorber can reduce low-frequency resonance sounds such as tire cavity resonance sounds.

[0014] In the above-described resonance sound absorber, the neck portion may be provided on the inner surface of the cylindrical portion on the side that is attached to the inner cavity surface, thereby making it possible to suppress movement of the neck portion due to centrifugal force when the tire rotates.

[0015] In the above-described resonance sound absorber, the box main body may include a support portion provided within the cylindrical portion and connecting a portion of the inner surface of the cylindrical portion that is attached to the lumen surface with a portion on the opposite side from the side that is attached to the lumen surface. In this resonance sound absorber, the inner surface of the cylindrical portion can be supported by the support portion, thereby suppressing deformation of the resonance box due to centrifugal force when the tire rotates.

[0016] In the above-described resonant sound absorber, the outer peripheral surface of the lid of the lid mounting part may be provided with a convex portion, a flat portion, or a concave portion. In this case, for example, when gripping the lid and attaching it to the body mounting part of the box body, the lid can be gripped more securely than if the outer peripheral surface of the lid mounting part were cylindrical. Furthermore, in this resonant sound absorber, by providing a convex portion or the like on the outer peripheral surface of the lid mounting part, the rotational position of the lid can be easily determined when rotating the lid to attach it to the box body.

[0017] The above-mentioned resonance sound absorber may include a bottom wall portion attached to the inner cavity surface and a support wall portion supporting the resonance box against the bottom wall portion, and the support wall portion may support the resonance box in a spaced-apart state from the bottom wall portion. In this resonance sound absorber, the resonance box is spaced apart from the bottom wall portion. Therefore, even if the tire deforms due to unevenness in the road surface or the like, deformation of the resonance box is suppressed in the resonance sound absorber. As a result, the resonance sound absorber can more appropriately absorb sound by suppressing deformation of the resonance box.

[0018] According to various aspects of the present disclosure, the resonance box can be easily formed.

[0019] FIG. 1 is a schematic cross-sectional view of a tire to which a resonance sound absorber according to an embodiment is attached. FIG. 2 is a schematic front view of a resonance sound absorber according to an embodiment. FIG. 3 is a schematic rear view of a resonance sound absorber according to an embodiment. FIG. 4 is a schematic side view of a resonance sound absorber according to an embodiment, viewed from the lid side. FIG. 5 is a schematic side view of a resonance sound absorber according to an embodiment, viewed from the first opening side. FIG. 6 is a schematic cross-sectional view taken along line VI-VI in FIG. 5. FIG. 7 is a schematic side view of a box main body with the lid removed, viewed from the second opening side. FIG. 8(a) is a schematic cross-sectional view of the lid taken along line VIIIa-VIIIa in FIG. 4. FIG. 8(b) is a schematic cross-sectional view of the lid taken along line VIIIb-VIIIb in FIG. 4. FIG. 9 is a diagram for explaining a method for calculating the resonant frequency of a Helmholtz resonance structure.

[0020] Hereinafter, with reference to the drawings, an embodiment of a resonant sound absorber according to the present disclosure will be described in detail. In the drawings, the same or corresponding parts are designated by the same reference numerals, and duplicate explanations will be omitted. Furthermore, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively.

[0021] 1 is a schematic cross-sectional view of a tire equipped with a resonance sound absorber according to an embodiment. In the tire T, cavity resonance can occur, in which the air in the cavity S resonates due to vibrations caused by passing over uneven road surfaces while the vehicle is traveling. The frequency of the cavity resonance is approximately 200 Hz to 300 Hz, typically approximately 250 Hz. The resonance sound absorber 1 according to this embodiment is attached to the cavity surface Ta of the tire T in order to efficiently absorb cavity resonance in the low frequency band. The cavity surface Ta is the inner circumferential surface of the tread Tb of the tire T.

[0022] In this embodiment, two resonance sound absorbers 1 are provided in the cavity S of the tire T. In this embodiment, the two resonance sound absorbers 1 are attached to the cavity surface Ta at positions offset by 180° in the rotational direction of the tire T. However, the number and attachment positions of the resonance sound absorbers 1 are not limited to the configuration shown in FIG. 1 . The resonance sound absorbers 1 are attached to the cavity surface Ta of the tire T with double-sided adhesive tape TP attached to the attachment surface 4 a of the resonance sound absorber 1. Note that the attachment of the resonance sound absorber 1 is not limited to using the double-sided adhesive tape TP, and it may be attached by any appropriate method, such as using an adhesive, for example.

[0023] A resonance sound absorber 1 according to an embodiment will be described with reference to Figs. 2 to 7. Fig. 2 is a schematic front view of a resonance sound absorber according to an embodiment. Fig. 3 is a schematic rear view of a resonance sound absorber according to an embodiment. Fig. 4 is a schematic side view of a resonance sound absorber according to an embodiment, viewed from the lid side. Fig. 5 is a schematic side view of a resonance sound absorber according to an embodiment, viewed from the first opening side. Fig. 6 is a schematic cross-sectional view taken along line VI-VI in Fig. 5. Fig. 7 is a schematic side view of the box main body with the lid removed, viewed from the second opening side.

[0024] As shown in Figures 2 to 7, the resonance sound absorber 1 according to this embodiment includes a resonance box 2, a support wall portion 3, and a bottom wall portion 4. The bottom wall portion 4 is attached to the inner cavity surface Ta of the tire T. The bottom wall portion 4 has a mounting surface 4a that is attached to the inner cavity surface Ta of the tire T. The bottom wall portion 4 is formed in the shape of a rectangular plate that is long in a first direction D1 and short in a second direction D2 that is perpendicular to the first direction D1. The direction perpendicular to the first direction D1 and the second direction D2 is referred to as a third direction D3. The third direction D3 is also the height direction of the resonance sound absorber 1.

[0025] The support wall 3 supports the resonance box 2 relative to the bottom wall 4. The support wall 3 supports the resonance box 2 while spaced apart from the bottom wall 4. Here, the resonance box 2 and the support wall 3 are arranged side by side in the third direction D3. The support wall 3 has a first support wall 3A and a second support wall 3B. The first support wall 3A and the second support wall 3B are formed in a rectangular plate shape extending in the first direction D1. The first support wall 3A connects one end of the bottom wall 4 in the second direction D2 to one outer surface of the resonance box 2 in the second direction D2. The second support wall 3B connects the other end of the bottom wall 4 in the second direction D2 to the other outer surface of the resonance box 2 in the second direction D2. The first support wall 3A and the second support wall 3B support the resonance box 2 while spaced apart from the bottom wall 4 in the third direction D3.

[0026] The resonance box 2 has a Helmholtz resonance structure. To realize the Helmholtz resonance structure, the resonance box 2 has a hollow portion 12 therein and a first opening 13 that opens the hollow portion 12 to the outside. More specifically, the resonance box 2 includes a box main body 10 and a lid 20.

[0027] The box main body 10 comprises an outer wall 11, a hollow portion 12 formed within the outer wall 11, a first opening 13 that opens the hollow portion 12 to the outside of the outer wall 11 (outside the resonance box 2), a second opening 14 that opens the hollow portion 12 to the outside of the outer wall 11, a hollow neck portion 15 that connects the first opening 13 and the hollow portion 12, a support portion 16, and a box engagement portion 17.

[0028] The outer wall 11 has self-supporting properties to the extent that it can maintain its shape in a stationary state. The outer wall 11 is non-breathable. The outer wall 11 has at least one of a Shore A hardness of 40 to 100 and a Shore D hardness of 10 to 70. In this case, the Shore A hardness of the outer wall 11 may be 50 to 80 or 60 to 70. The Shore D hardness of the outer wall 11 may be 10 to 50 or 10 to 40.

[0029] The Shore A hardness of the outer wall 11 can be measured using a durometer in accordance with JIS K6253-3; for example, a GS-709N TYPE A manufactured by Teclock Corporation can be used. The Shore D hardness of the outer wall 11 can be measured using a durometer in accordance with JIS K6253-3; for example, a GS-720N TYPE D manufactured by Teclock Corporation can be used. If the allowable number of stacked test pieces specified in JIS K6253-3 (three or less) does not satisfy the specified measurement thickness (6 mm or more), more than three pieces can be stacked and the measurement can be performed at the specified thickness.

[0030] The material of the outer wall 11 includes, for example, an elastomer such as a thermoplastic elastomer, a plastic, a rubber, a rubber-like material, or other resin.

[0031] Examples of elastomer materials include thermoplastic elastomers such as styrene block copolymer (SBC), polyolefin (TPO), polyurethane (TPU), polyester (TPC), polyamide (TPA), dynamically crosslinked (TPV), soft polyvinyl chloride (PVC), and acrylic.

[0032] 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.

[0033] 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.

[0034] Examples of rubber-like materials include UV-curable acrylic rubber-like materials.

[0035] The outer wall 11 includes a cylindrical portion 11a and a sealing wall portion 11b. The thickness of the outer wall 11 is, for example, about 0.1 mm to 2 mm. That is, the thickness of each of the cylindrical portion 11a and the sealing wall portion 11b is, for example, about 0.1 mm to 2 mm.

[0036] The tubular portion 11a has a hollow portion 12 therein. The tubular portion 11a has a cylindrical shape extending in the first direction D1. In this embodiment, the inner circumferential surface and the outer circumferential surface of the tubular portion 11a each have a cylindrical shape.

[0037] The sealing wall portion 11b closes the opening at one end of the cylindrical portion 11a in the first direction D1. The sealing wall portion 11b is formed in a flat plate shape extending in a direction intersecting the first direction D1 and is connected to the one end of the cylindrical portion 11a.

[0038] The outer wall 11 has no wall portion at the end opposite to the side where the sealing wall portion 11b is provided in the first direction D1. The outer wall 11 has an open end opposite to the side where the side wall portion 11c is provided in the first direction D1. This open portion of the outer wall 11 becomes the second opening 14.

[0039] The first opening 13 is formed in the outer wall 11 and penetrates the outer wall 11. In this embodiment, the first opening 13 is provided in the sealing wall portion 11b of the outer wall 11. The first opening 13 serves as an entrance for tire cavity resonance sound in the resonance box 2. The shape (cross-sectional shape) of the first opening 13 is not particularly limited and can be various shapes such as circular, triangular, rectangular, polygonal, and elliptical. In this embodiment, the first opening 13 is a circular hole. In other words, the cross-sectional shape of the first opening 13 is circular. The inner diameter of the first opening 13 is, for example, approximately 1 mm to 5 mm.

[0040] The second opening 14 is formed in the outer wall 11 and penetrates the outer wall 11. The second opening 14 is provided at the end of the tubular portion 11a opposite to the side where the sealing wall portion 11b is provided in the first direction D1. In other words, the first opening 13 and the second opening 14 are provided at both ends of the outer wall 11 in the first direction D1. In this embodiment, the shape (cross-sectional shape) of the second opening 14 is circular. In this embodiment, the size of the second opening 14 is larger than the size of the first opening 13.

[0041] In this way, the box main body 10 has an outer wall 11, and thereby has a hollow portion 12 inside and a second opening 14 that opens the hollow portion 12 to the outside (outside the box main body 10).

[0042] At least a portion of the neck portion 15 is disposed within the outer wall 11. In this embodiment, the entire neck portion 15 is disposed within the outer wall 11. The base end and the tip end of the neck portion 15 are open ends at which a hollow portion 15a of the neck portion 15 is exposed. The base end of the neck portion 15 is connected to the first opening 13. The hollow portion 15a of the neck portion 15 opens from the first opening 13 to the outside of the outer wall 11 (outside the resonance box 2) at the base end of the neck portion 15. The tip end of the neck portion 15 is located within the hollow portion 12. The hollow portion 15a of the neck portion 15 opens to the hollow portion 12 at the tip end of the neck portion 15. The end of the neck portion 15 on the hollow portion 12 side opens toward the second opening 14.

[0043] The neck portion 15 is non-air permeable, similar to the resonance box 2. The neck portion 15 has at least one of the Shore A hardness and the Shore D hardness similar to the resonance box 2. The material of the neck portion 15 can be the same as the material of the resonance box 2.

[0044] The hollow portion 15a of the neck portion 15 has, for example, a cross section that is equal to or larger than the cross section of the first opening 13. By increasing the extension length of the neck portion 15, the resonance frequency of the resonance box 2 can be lowered. In other words, by increasing the extension length of the neck portion 15, resonance sounds in the low frequency range can be reduced. The extension length of the neck portion 15 is the length of the extension axis of the neck portion 15 from the base end of the neck portion 15 to the tip end of the neck portion 15.

[0045] The neck portion 15 is provided on the inner surface of the tubular portion 11a on the side that is attached to the lumen surface Ta of the tire T. That is, the neck portion 15 is provided on the inner surface of the tubular portion 11a at a location closer to the bottom wall portion 4 that is attached to the lumen surface Ta of the tire T. The neck portion 15 is, for example, integrated (integrally molded) with the tubular portion 11a and connected to the tubular portion 11a. The neck portion 15 extends in the first direction D1, but the extending direction, extending shape, etc. of the neck portion 15 are not particularly limited.

[0046] The support portion 16 is provided inside the tubular portion 11a. The support portion 16 connects a portion of the inner surface of the tubular portion 11a of the outer wall 11 on the side that is attached to the lumen surface Ta of the tire T (the bottom wall portion 4 side) to a portion on the opposite side from the side that is attached to the lumen surface Ta of the tire T. In other words, the support portion 16 extends in the radial direction of the tire T when the resonance sound absorber 1 is attached to the lumen surface Ta of the tire T.

[0047] The support portion 16 supports a portion of the tubular portion 11a opposite to the side attached to the lumen surface Ta of the tire T, relative to the side attached to the lumen surface Ta of the tire T. The support portion 16 is configured with a plate-shaped rib. The support portion 16 extends from the neck portion 15 in the third direction D3. That is, the support portion 16 supports a portion of the inner surface of the tubular portion 11a opposite to the side attached to the lumen surface Ta of the tire T, relative to the side attached to the lumen surface Ta of the tire T, via the neck portion 15. The support portion 16 has a shape that allows the hollow portion 12 to be maintained as a single space. For example, the support portion 16 has a shape in which a portion between the neck portion 15 and the second opening 14 is cut out.

[0048] The box engaging portion 17 is provided on the outer peripheral surface of the tubular portion 11a. Here, a lid portion 20 is attached to the box main body 10 so as to cover the second opening 14. The box main body 10 has a main body mounting portion A, which is the portion to which the lid portion 20 is attached. The main body mounting portion A is the portion covered by the lid portion 20. The main body mounting portion A is provided with the second opening 14. In this embodiment, the main body mounting portion A is configured by the end of the tubular portion 11a on the side where the second opening 14 is provided. The main body mounting portion A has a tubular shape and has the second opening at one end. In this embodiment, the main body mounting portion A has a cylindrical shape. Furthermore, the main body outer peripheral surface A1, which is the outer peripheral surface of the main body mounting portion A, has a cylindrical shape. The box engaging portion 17 is provided on the outer peripheral surface of the tubular portion 11a, in the portion of the main body outer peripheral surface A1 of the main body mounting portion A.

[0049] In this embodiment, the box engaging portion 17 is composed of a first box protrusion (box protrusion) 17A and a second box protrusion (box protrusion) 17B. The first box protrusion 17A and the second box protrusion 17B each protrude outward from the main body outer peripheral surface A1. The first box protrusion 17A and the second box protrusion 17B are provided at positions on the main body outer peripheral surface A1 that are shifted from each other by 180° in the circumferential direction.

[0050] The lid portion 20 covers the second opening 14. The lid portion 20 airtightly seals the second opening 14. The lid portion 20 includes a lid engaging portion 24. The lid portion 20 is attached to the box main body 10 so as to cover the second opening 14 by engaging the lid engaging portion 24 with the box engaging portion 17 provided on the box main body 10.

[0051] The lid portion 20 will be described in detail with reference to Figures 8(a) and 8(b). Figure 8(a) is a schematic cross-sectional view of the lid portion taken along line VIIIa-VIIIa in Figure 4. Figure 8(b) is a schematic cross-sectional view of the lid portion taken along line VIIIb-VIIIb in Figure 4. As shown in Figures 8(a) and 8(b), the lid portion 20 includes a lid sealing portion 21, a lid mounting portion 22, a cylindrical portion 23, and a lid engaging portion 24.

[0052] The lid sealing portion 21 seals the second opening 14. The lid mounting portion 22 surrounds the main body mounting portion A of the box main body 10 from the outside. The lid mounting portion 22 has a cylindrical shape extending in the first direction D1. The lid inner peripheral surface 22a, which is the inner peripheral surface of the lid mounting portion 22, has a cylindrical shape. The diameter of the lid inner peripheral surface 22a is slightly larger than the diameter of the main body outer peripheral surface A1 of the main body mounting portion A. The main body mounting portion A is inserted inside the lid mounting portion 22. The lid sealing portion 21 seals the opening at one end of the cylindrical lid mounting portion 22.

[0053] The lid sealing portion 21 has a sealing surface 21a that abuts against the end of the body mounting portion A to seal the second opening 14 when attached to the box body portion 10. The sealing surface 21a faces the box body portion 10. The cylindrical portion 23 is provided on the sealing surface 21a of the lid sealing portion 21 and protrudes a predetermined height from the sealing surface 21a. The cylindrical portion 23 has a cylindrical shape. The outer diameter of the cylindrical portion 23 is slightly smaller than the inner diameter of the body mounting portion A. The end of the body mounting portion A is inserted between the lid mounting portion 22 and the cylindrical portion 23. By configuring the end of the body mounting portion A to be inserted into the gap between the lid mounting portion 22 and the cylindrical portion 23, the second opening 14 can be more reliably sealed by the lid portion 20.

[0054] The lid engaging portion 24 engages with the box engaging portion 17 of the box main body 10. The lid engaging portion 24 is provided on the lid inner peripheral surface 22a. The box engaging portion 17 and the lid engaging portion 24 are engaged with each other by rotating the lid portion 20 relative to the main body mounting portion A in a state in which the lid portion 20 is placed over the main body mounting portion A of the box main body 10. Here, as shown in FIG. 4 , the direction in which the lid portion 20 is rotated relative to the box main body 10 when engaging the box engaging portion 17 with the lid engaging portion 24 is defined as the engagement rotation direction Y. As shown in FIG. 4 , the engagement rotation direction Y is the direction in which the lid portion 20 is rotated rightward (clockwise) when the resonance sound absorber 1 is viewed from the lid portion 20 side.

[0055] The lid engagement portion 24 is composed of a first lid engagement groove (lid engagement groove) 24A and a second lid engagement groove (lid engagement groove) 24B. The first lid engagement groove 24A and the second lid engagement groove 24B are provided on the lid inner peripheral surface 22a at positions offset from each other by 180° in the circumferential direction.

[0056] As shown in FIG. 8A , the first box protrusion 17A is fitted into the first lid engagement groove 24A. The first lid engagement groove 24A engages with the first box protrusion 17A of the box main body 10. The first lid engagement groove 24A has a groove introduction portion 24Aa and a groove accommodating portion 24Ab. The groove introduction portion 24Aa extends in the first direction D1. That is, the groove introduction portion 24Aa extends along the insertion direction of the main body attachment portion A into the lid attachment portion 22. The groove introduction portion 24Aa extends from the end of the lid attachment portion 22 opposite the lid sealing portion 21 side toward the lid sealing portion 21 side. The end of the groove introduction portion 24Aa opposite the lid sealing portion 21 side is open in the first direction D1. The end of the groove introduction portion 24Aa opposite to the lid sealing portion 21 side becomes an entrance 24Ac for introducing the first box protrusion 17A into the first lid engagement groove 24A.

[0057] The groove accommodating portion 24Ab extends in the circumferential direction of the lid inner peripheral surface 22a. The groove accommodating portion 24Ab is connected to the end of the groove introducing portion 24Aa on the lid sealing portion 21 side. The groove accommodating portion 24Ab extends from the end of the groove introducing portion 24Aa toward the opposite side of the engagement rotation direction Y. In this embodiment, the groove accommodating portion 24Ab communicates with the lid inner peripheral surface 22a of the lid mounting portion 22 and the lid outer peripheral surface 22b, which is the outer peripheral surface of the lid mounting portion 22 (see FIG. 3). Because the groove accommodating portion 24Ab is a hole, it is easy to check from the outside of the lid portion 20 whether the first box protrusion 17A is fitted into the groove accommodating portion 24Ab. However, the groove accommodating portion 24Ab is not limited to communicating with the lid inner peripheral surface 22a and the lid outer peripheral surface 22b of the lid mounting portion 22. The groove accommodating portion 24Ab may be a groove provided in the lid inner peripheral surface 22a.

[0058] The position at which groove accommodating portion 24Ab is provided in first direction D1 is a position at which, when first box protrusion 17A is accommodated in groove accommodating portion 24Ab, the end face of main body mounting portion A abuts against sealing surface 21a of lid portion 20. If main body mounting portion A is elastically deformable, the position at which groove accommodating portion 24Ab is provided in first direction D1 may be a position at which, when first box protrusion 17A is accommodated in groove accommodating portion 24Ab, the end face of main body mounting portion A is pressed against sealing surface 21a of lid portion 20.

[0059] A lid protrusion 24Ad that prevents the first box protrusion 17A accommodated in the groove accommodating portion 24Ab from slipping out of the groove accommodating portion 24Ab is provided on the wall surface of the groove accommodating portion 24Ab of the first lid engagement groove 24A. The lid protrusion 24Ad can introduce the first box protrusion 17A into the groove accommodating portion 24Ab while preventing the first box protrusion 17A from slipping out of the groove accommodating portion 24Ab.

[0060] As shown in FIG. 8( b), the second box protrusion 17B is fitted into the second lid engagement groove 24B. The second lid engagement groove 24B engages with the second box protrusion 17B of the box main body 10. The second lid engagement groove 24B has a groove introduction portion 24Ba and a groove accommodating portion 24Bb. The groove introduction portion 24Ba extends in the first direction D1. That is, the groove introduction portion 24Ba extends along the insertion direction of the main body attachment portion A into the inside of the lid attachment portion 22. The groove introduction portion 24Ba extends from the end of the lid attachment portion 22 opposite the lid sealing portion 21 side toward the lid sealing portion 21 side. The end of the groove introduction portion 24Ba opposite the lid sealing portion 21 side is open in the first direction D1. The end of the groove introduction portion 24Ba opposite to the lid sealing portion 21 side becomes an entrance 24Bc for introducing the second box protrusion portion 17B into the second lid engagement groove 24B.

[0061] The groove accommodating portion 24Bb extends in the circumferential direction of the lid inner peripheral surface 22a. The groove accommodating portion 24Bb is connected to the end of the groove introducing portion 24Ba on the lid sealing portion 21 side. The groove accommodating portion 24Bb extends from the end of the groove introducing portion 24Ba toward the opposite side of the engagement rotation direction Y. In this embodiment, the groove accommodating portion 24Bb communicates with the lid inner peripheral surface 22a and the lid outer peripheral surface 22b of the lid mounting portion 22 (see FIG. 2). Because the groove accommodating portion 24Bb is a hole, it is easy to check from the outside of the lid 20 whether the second box protrusion 17B is fitted into the groove accommodating portion 24Bb. However, the groove accommodating portion 24Bb is not limited to communicating with the lid inner peripheral surface 22a and the lid outer peripheral surface 22b of the lid mounting portion 22. The groove accommodating portion 24Bb may be a groove provided in the lid inner peripheral surface 22a.

[0062] The position at which groove accommodating portion 24Bb is provided in first direction D1 is a position at which, when second box protrusion 17B is accommodated in groove accommodating portion 24Bb, the end face of main body mounting portion A abuts against sealing surface 21 a of lid portion 20. If main body mounting portion A is elastically deformable, the position at which groove accommodating portion 24Bb is provided in first direction D1 may be a position at which, when second box protrusion 17B is accommodated in groove accommodating portion 24Bb, the end face of main body mounting portion A is pressed against sealing surface 21 a of lid portion 20.

[0063] A lid protrusion 24Bd that prevents the second box protrusion 17B accommodated in the groove accommodating portion 24Bb from slipping out of the groove accommodating portion 24Bb is provided on the wall surface of the groove accommodating portion 24Bb of the second lid engagement groove 24B. The lid protrusion 24Bd prevents the second box protrusion 17B from slipping out of the groove accommodating portion 24Bb while allowing the second box protrusion 17B to be introduced into the groove accommodating portion 24Bb.

[0064] Two flat portions 22c are provided on the lid outer peripheral surface 22b of the lid attachment portion 22. The two flat portions 22c are provided at positions 180° apart from each other in the circumferential direction. The flat portions 22c have flat surfaces. In the present embodiment, as an example, the groove accommodating portion 24Ab opens into one of the flat portions 22c, and the groove accommodating portion 24Bb opens into the other flat portion 22c.

[0065] The box main body 10, lid 20, support wall 3, and bottom wall 4 configured in this manner can be manufactured by, for example, injection molding, extrusion molding, modeling using a 3D printer, salt coagulation, etc.

[0066] Next, a configuration for reducing resonance noise within the tire cavity S of the tire T using the resonance box 2 of the resonance sound absorber 1 will be described. Here, as shown in FIG. 1 , F is the frequency of tire cavity resonance noise, c is the speed of light, R is the radius of the cavity surface Ta of the tire T, r is the radius of the rim Ha of the wheel H mounted on the tire T, and π is the circular constant. In this case, the frequency of tire cavity resonance noise is calculated by F = c / ((R + r) × π). It is preferable that the resonance box 2 of the resonance sound absorber 1 has a Helmholtz resonance structure that generates Helmholtz resonance with a resonance frequency within a range of ±100 Hz of the frequency of tire cavity resonance noise calculated from F = c / ((R + r) × π).

[0067] The Helmholtz resonance structure is a structure that includes components of a Helmholtz resonator that resonates with sound incident through an opening. In the resonance sound absorber 1, the Helmholtz resonance structure is formed by the resonance box 2. That is, in the resonance box 2, the non-air-permeable neck portion 15 connects the first opening 13 and the hollow portion 12, and therefore the resonance frequency of the resonance box 2, which functions as a Helmholtz resonator, varies depending on the extension length of the neck portion 15, the inner diameter of the first opening 13, and the like. For example, the longer the extension length of the neck portion 15, the lower the resonance frequency. Furthermore, the smaller the inner diameter of the first opening 13, the lower the resonance frequency. For this reason, it is preferable that these conditions of the resonance box 2 be adjusted so that Helmholtz resonance occurs at a resonance frequency within a range of ±100 Hz of the frequency of tire cavity resonance sound calculated from F = c / ((R + r) × π).

[0068] In this way, by providing a Helmholtz resonance structure that generates Helmholtz resonance at a resonance frequency within a range of ±100 Hz of the frequency of tire cavity resonance noise, tire cavity resonance noise can be reduced.

[0069] 9 is a diagram illustrating a method for calculating the resonant frequency of the Helmholtz resonance structure. The resonant frequency of the Helmholtz resonance structure, which resonates with the sound incident from the first opening 13, can be adjusted from various dimensions of the hollow portion 12 according to this calculation method.

[0070] In Figure 9, V is the volume of the hollow portion 12. If a neck portion 15 extends into the hollow portion 12, the volume obtained by subtracting the volume of the neck portion 15 is defined as V. α is the area of ​​the first opening 13 when viewed from the thickness direction of the outer wall 11. δ is an opening end correction; for example, if the shape of the first opening 13 is circular, δ can be calculated as 0.8 times the diameter of the first opening 13. If the shape of the first opening 13 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 first opening 13. L is the depth of the first opening 13, i.e., the extension length of the neck portion 15 (hollow portion).

[0071] As described above, in the resonance sound absorber 1, the box engaging portion 17 provided on the box main body 10 and the lid engaging portion 24 provided on the lid portion 20 are engaged with each other, thereby attaching the lid portion 20 to the box main body 10. In this way, in the resonance sound absorber 1, by engaging the box engaging portion 17 with the lid engaging portion 24, it is possible to easily form the resonance box 2 having the hollow portion 12 therein.

[0072] In the resonance sound absorber 1, the body outer peripheral surface A1 of the body mounting portion A of the box body 10 and the lid inner peripheral surface 22a of the lid portion 20 are cylindrical. In other words, with the lid portion 20 placed over the body outer peripheral surface A1 of the body mounting portion A, the lid portion 20 can be rotated relative to the box body 10. In the resonance sound absorber 1, the box engaging portion 17 and the lid engaging portion 24 are engaged by rotating the lid portion 20 relative to the box body 10. In this way, in the resonance sound absorber 1, the lid portion 20 can be easily attached to the box body 10 by rotating the lid portion 20 relative to the box body 10.

[0073] The box engagement portion 17 is made up of a first box protrusion 17A and a second box protrusion 17B. The lid engagement portion 24 is made up of a first lid engagement groove 24A and a second lid engagement groove 24B. As a result, in the resonant sound absorber 1, the first box protrusion 17A and the second box protrusion 17B are engaged with the first lid engagement groove 24A and the second lid engagement groove 24B, thereby more reliably engaging the box main body 10 and the lid 20.

[0074] The groove accommodating portion 24Ab of the first lid engagement groove 24A is provided with a lid protrusion 24Ad that prevents the first box protrusion 17A from slipping out. The groove accommodating portion 24Bb of the second lid engagement groove 24B is provided with a lid protrusion 24Bd that prevents the second box protrusion 17B from slipping out. In this case, when the lid 20 is attached to the box main body 10, the lid 20 is prevented from coming off the box main body 10.

[0075] The outer wall 11 of the box body 10 has a cylindrical tubular portion 11a. This prevents stress from concentrating at one point on the tubular portion 11a in the resonance sound absorber 1, even if the sound pressure inside the cavity S of the tire T changes. In this way, the cylindrical tubular portion 11a in the resonance sound absorber 1 ensures the rigidity of the box body 10.

[0076] The first opening 13 is provided in the sealing wall portion 11b of the outer wall 11. In this case, the resonance sound absorber 1 can take sound (air vibrations) into the hollow portion 12 of the resonance box 2 through the first opening 13 provided in the sealing wall portion 11b of the box main body 10.

[0077] In the resonance sound absorber 1, the resonance box 2 includes a neck portion 15 that connects the first opening 13 and the hollow portion 12. Therefore, in the resonance sound absorber 1, the resonant frequency of Helmholtz resonance can be adjusted by adjusting the length of the neck portion 15. Furthermore, by lengthening the neck portion 15, Helmholtz resonance with a resonant frequency in the low-frequency range can be generated. Therefore, the resonance sound absorber 1 can reduce low-frequency resonance sounds such as tire cavity resonance sounds.

[0078] The resonance sound absorber 1 is provided on the inner surface of the cylindrical portion 11a of the outer wall 11, on the side that is attached to the inner cavity surface Ta of the tire T. This makes it possible for the resonance sound absorber 1 to suppress movement of the neck portion 15 due to centrifugal force when the tire T rotates.

[0079] The box main body 10 includes a support portion 16 that connects a portion of the inner surface of the tubular portion 11a that is attached to the lumen surface Ta of the tire T with a portion on the opposite side of the side that is attached to the lumen surface Ta of the tire T. This allows the resonance sound absorber 1 to support the inner surface of the tubular portion 11a with the support portion 16, thereby suppressing deformation of the resonance box 2 due to centrifugal force when the tire T rotates.

[0080] A flat portion 22c is provided on the lid outer peripheral surface 22b of the lid mounting portion 22. In this case, for example, when gripping the lid portion 20 and attaching it to the main body mounting portion A of the box main body 10, the lid portion 20 can be gripped more reliably than if the lid outer peripheral surface 22b of the lid mounting portion 22 were cylindrical. Furthermore, because the flat portion 22c is provided on the lid outer peripheral surface 22b of the lid mounting portion 22 of this resonance sound absorber 1, the rotational position of the lid portion 20 can be easily grasped when rotating the lid portion 20 to attach it to the main body mounting portion A.

[0081] In the resonance sound absorber 1, the resonance box 2 is supported by the support wall 3 in a state spaced apart from the bottom wall 4 that is attached to the inner cavity surface Ta of the tire T. Therefore, in the resonance sound absorber 1, deformation of the resonance box 2 is suppressed even when the tire T is deformed due to unevenness of the road surface, etc. This allows the resonance sound absorber 1 to more appropriately absorb sound by suppressing deformation of the resonance box 2. Furthermore, because the bottom wall 4 is spaced apart from the resonance box 2, the flexibility of the bottom wall 4 is prevented from being affected by the resonance box 2. This allows the resonance sound absorber 1 to be more easily attached to the curved inner cavity surface Ta of the tire T.

[0082] The present disclosure is not limited to the above-described embodiments, and modifications can be made as appropriate without departing from the spirit of the present disclosure.

[0083] For example, the first opening 13 is not limited to being provided in the sealing wall portion 11b of the outer wall 11. The first opening 13 may be provided in the tubular portion 11a of the outer wall 11, or may be provided in the lid portion 20. Furthermore, the lid outer peripheral surface 22b of the lid mounting portion 22 of the lid portion 20 may be provided with a convex portion or a concave portion instead of the flat portion 22c.

[0084] Furthermore, for example, the shape of the resonance box 2, the position of the neck portion 15, the shape of the support portion 16, the shape of the support wall portion 3, the shape of the bottom wall portion 4, etc. are not particularly limited and can be modified in various ways. Furthermore, the resonance sound absorber 1 may have a configuration that does not include the support portion 16.

[0085] The box engaging portion 17 and the lid engaging portion 24 are not limited to a configuration in which the box engaging portion 17 is configured with a convex portion and the lid engaging portion 24 is configured with a groove. The box engaging portion 17 may be configured with a groove and the lid engaging portion 24 may be configured with a convex portion that fits into the groove of the box engaging portion 17. Furthermore, the box engaging portion 17 and the lid engaging portion 24 are not limited to a configuration in which the box engaging portion 17 and the lid engaging portion 24 are configured with a convex portion and a groove, respectively. Various configurations can be adopted for the box engaging portion 17 and the lid engaging portion 24 as long as they are configured to be able to engage with each other.

[0086] In the above embodiment, the lid mounting portion 22 of the lid portion 20 surrounds the body mounting portion A of the box body portion 10 from the outside. This is not limiting, and a configuration in which the lid mounting portion of the lid portion 20 is inserted into the body mounting portion A of the box body portion 10 may also be used. A box engaging portion may be provided on the inner peripheral surface of the body mounting portion A of the box body portion 10, and a lid engaging portion may be provided on the outer peripheral surface of the lid mounting portion of the lid portion 20 inserted into the body mounting portion A. Even in this configuration, it is sufficient that the sealing surface 21 a of the lid portion 20 abuts against the end of the body mounting portion A to seal the second opening 14. Even in this case, the resonance box 2 can be easily formed by engaging the box body portion 10 and the lid portion 20 with each other, as with the resonance sound absorber 1 according to the above embodiment.

[0087] The gist of the present disclosure is as follows: [1] to

[11] [1] A resonance sound absorber attached to the inner cavity surface of a tire, comprising: a resonance box having a hollow portion therein and a first opening that opens the hollow portion to the outside, the resonance box having: a box main body having the hollow portion therein and a second opening that opens the hollow portion to the outside, and a lid that covers the second opening, the first opening being provided in the box main body or the lid, and the lid being attached to the box main body so as to cover the second opening by engaging a lid engaging portion provided on the lid with a box engaging portion provided on the box main body. [2] The resonant sound absorber described in [1] above, wherein the box main body has a main body mounting portion in which the second opening is provided and to which the lid is attached, the main body mounting portion being tubular and having the second opening at one end, the main body outer peripheral surface which is the outer peripheral surface of the main body mounting portion being cylindrical, the lid has a lid sealing portion which seals the second opening, and a lid mounting portion which surrounds the main body mounting portion from the outside, the lid inner peripheral surface which is the inner peripheral surface of the lid mounting portion being cylindrical, the box engaging portion being provided on the main body outer peripheral surface, and the lid engaging portion being provided on the lid inner peripheral surface, the box engaging portion and the lid engaging portion being engaged with each other by rotating the lid portion relative to the main body mounting portion with the lid portion placed on the main body mounting portion. [3] The resonance sound absorber according to [2] above, wherein the box engagement portion is constituted by a box protrusion protruding from the outer peripheral surface of the main body, and the lid engagement portion is constituted by a lid engagement groove provided on the inner peripheral surface of the lid and into which the box protrusion is fitted. [4] The lid engagement groove has a groove accommodating portion that accommodates the box protrusion when the second opening is sealed by the lid sealing portion, and the resonance sound absorber according to [3] above, wherein the lid engagement groove has a groove accommodating portion that accommodates the box protrusion when the second opening is sealed by the lid sealing portion, and a lid protrusion that prevents the box protrusion accommodated in the groove accommodating portion from coming out of the groove accommodating portion is provided on a wall surface of the lid engagement groove.[5] The resonant sound absorber according to any one of [2] to [4] above, wherein the box main body comprises an outer wall having a cylindrical tubular portion having the hollow portion inside and a sealing wall portion that closes an opening at one end of the tubular portion, and the second opening is provided at an end of the tubular portion opposite to the side on which the sealing wall portion is provided. [6] The resonant sound absorber according to [5] above, wherein the first opening is provided in the sealing wall portion. [7] The resonant sound absorber according to [6] above, wherein the box main body comprises a hollow neck portion that communicates with the first opening and the hollow portion. [8] The resonant sound absorber according to [7] above, wherein the neck portion is provided on the inner surface of the tubular portion on the side that is attached to the inner cavity surface. [9] The resonant sound absorber according to any one of [5] to [8] above, wherein the box main body is provided within the cylindrical portion and includes a support portion that connects a portion of the inner surface of the cylindrical portion that is attached to the lumen surface with a portion on the opposite side from the side that is attached to the lumen surface.

[10] The resonant sound absorber according to any one of [2] to [9] above, wherein the outer circumferential surface of the lid of the lid attachment portion is provided with a convex portion, a flat portion, or a concave portion.

[11] The resonant sound absorber according to any one of [1] to

[10] above, comprising: a bottom wall that is attached to the lumen surface; and a support wall that supports the resonance box against the bottom wall, wherein the support wall supports the resonance box in a spaced-apart state from the bottom wall.

[0088] 1...resonance sound absorber, 2...resonance box, 3...support wall portion, 4...bottom wall portion, 10...box main body portion, 11...outer wall, 11a...tubular portion, 11b...sealing wall portion, 12...hollow portion, 13...first opening, 14...second opening, 15...neck portion, 16...support portion, 17...box engaging portion, 17A...first box convex portion (box convex portion), 17B...second box convex portion (box convex portion), 20...lid portion, 21...lid sealing portion, 22...lid mounting portion, 22a...lid inner peripheral surface, 22b...lid outer peripheral surface, 24...lid engaging portion, 24A...first lid engaging groove (lid engaging groove), 24Ab, 24Bb...groove accommodating portion, 24Ad, 24Bd...lid convex portion, 24B...second lid engaging groove (lid engaging groove), A...main body mounting portion, A1...main body outer peripheral surface, T...tire, Ta...inner cavity surface.

Claims

1. A resonance sound absorber attached to the inner cavity surface of a tire, comprising a resonance box having a hollow portion inside and a first opening that opens the hollow portion to the outside, the resonance box having a box main body portion having the hollow portion inside and a second opening that opens the hollow portion to the outside, and a lid portion that covers the second opening, the first opening being provided in the box main body portion or the lid portion, and the lid portion being attached to the box main body portion so as to cover the second opening by engaging a lid engaging portion provided on the lid portion with a box engaging portion provided on the box main body portion.

2. The box main body portion has a main body attachment portion where the second opening is provided and the lid portion is attached, the main body attachment portion being cylindrical, having the second opening at one end, the outer peripheral surface of the main body attachment portion being cylindrical, the lid portion having a lid sealing portion that seals the second opening and a lid attachment portion that surrounds the main body attachment portion from the outside, the inner peripheral surface of the lid attachment portion being cylindrical, the box engaging portion being provided on the outer peripheral surface of the main body, the lid engaging portion being provided on the inner peripheral surface of the lid, and the box engaging portion and the lid engaging portion being engaged with each other by relatively rotating the lid portion with respect to the main body attachment portion with the lid portion covering the main body attachment portion. The resonance sound absorber according to claim 1.

3. The box engaging portion is constituted by a box convex portion protruding from the outer peripheral surface of the main body, and the lid engaging portion is constituted by a lid engaging groove provided on the inner peripheral surface of the lid and into which the box convex portion is fitted. The resonance sound absorber according to claim 2.

4. The lid engaging groove has a groove accommodating portion that is a portion for accommodating the box convex portion in a state where the second opening is sealed by the lid sealing portion, and a lid convex portion is provided on the wall surface of the lid engaging groove to regulate the box convex portion accommodated in the groove accommodating portion from coming out of the groove accommodating portion. The resonance sound absorber according to claim 3.

5. The box main body portion includes an outer wall having a cylindrical portion presenting a cylindrical shape with the hollow portion inside, and a sealing wall portion closing an opening at one end of the cylindrical portion. The second opening is provided at an end of the cylindrical portion opposite to the side where the sealing wall portion is provided. The resonance sound absorber according to claim 2.

6. The first opening is provided in the sealing wall portion. The resonance sound absorber according to claim 5.

7. The box main body portion includes a hollow neck portion communicating the first opening and the hollow portion. The resonance sound absorber according to claim 6.

8. The neck portion is provided on the inner surface of the cylindrical portion on the inner surface side where it is attached to the inner cavity surface. The resonance sound absorber according to claim 7.

9. The box main body portion is provided inside the cylindrical portion and includes a support portion connecting a portion of the inner surface of the cylindrical portion on the side where it is attached to the inner cavity surface and a portion of the inner surface of the cylindrical portion on the side opposite to the side where it is attached to the inner cavity surface. The resonance sound absorber according to claim 5.

10. A convex portion, a flat portion, or a concave portion is provided on the outer peripheral surface of the lid of the lid attachment portion. The resonance sound absorber according to claim 2.

11. It includes a bottom wall portion attached to the inner cavity surface, and a support wall portion supporting the resonance box with respect to the bottom wall portion. The support wall portion supports the resonance box in a state separated from the bottom wall portion. The resonance sound absorber according to any one of claims 1 to 10.

Images