Resonant sound absorber

Abstract

A resonant sound absorber according to the present invention is attached to an attachment surface of a tire. The resonant sound absorber comprises a resonance box that has an opening and has a hollow part formed on the interior thereof. The resonance box comprises a bottom wall part that is made to face the attachment surface, an upper wall part that forms the hollow part together with the bottom wall part, and side wall parts that surround the hollow part. The bottom wall part is thicker than the upper wall part.

Description

Resonant sound absorber

[0001] The present disclosure relates to a resonant sound absorber that is mounted in the lumen of a tire.

[0002] For example, as described in Patent Document 1, a resonance sound absorber that absorbs sound using the principle of Helmholtz resonance is known. This resonance sound absorber absorbs resonance sounds generated in the tire cavity. This resonance sound absorber has a hollow space formed inside and a resonance box with an opening that connects the hollow space to the outside.

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

[0004] Centrifugal force is applied to the resonance absorber attached to the tire cavity as the tire rotates. When the centrifugal force deforms the resonance box of the resonance absorber, the hollow space inside also deforms, changing the frequency of sound absorbed by the resonance absorber.

[0005] Therefore, the present disclosure describes a resonance sound absorber that can suppress deformation of the resonance box even when centrifugal force is applied.

[0006] A resonant sound absorber according to one aspect of the present disclosure is a resonant sound absorber that is attached to a mounting surface of the tire cavity, and includes a resonance box that has an opening and a hollow portion formed inside, the resonance box having a bottom wall portion that faces the mounting surface, an upper wall portion that faces the bottom wall portion and forms the hollow portion between it and the bottom wall portion, and side wall portions that surround the hollow portion between the bottom wall portion and the upper wall portion, and the thickness of the bottom wall portion is thicker than the thickness of the upper wall portion.

[0007] In this resonance sound absorber, the resonance box has a hollow portion surrounded by a bottom wall portion, an upper wall portion, and a side wall portion. The thickness of the bottom wall portion is thicker than that of the upper wall portion. In other words, the upper wall portion is thinner than the bottom wall portion, thereby reducing the weight of the upper wall portion. The resonance sound absorber is attached so that the bottom wall portion faces the mounting surface of the tire. In other words, the lightweight upper wall portion is positioned above the bottom wall portion. As a result, even when centrifugal force is applied to the resonance box of the resonance sound absorber as the tire rotates, the lightweight upper wall portion can suppress the centrifugal force applied to the upper wall portion. Therefore, deformation of the upper wall portion of the resonance sound absorber is suppressed. Furthermore, the thick bottom wall portion can increase the rigidity of the resonance box. In this way, this resonance sound absorber can suppress deformation of the resonance box even when centrifugal force is applied.

[0008] A resonant sound absorber according to another aspect of the present disclosure is a resonant sound absorber that is attached to a mounting surface of the tire cavity, and includes a resonance box that has an opening and a hollow portion formed inside, the resonance box having a bottom wall portion that faces the mounting surface, an upper wall portion that faces the bottom wall portion and forms the hollow portion between it and the bottom wall portion, and a side wall portion that surrounds the hollow portion between the bottom wall portion and the upper wall portion, the opening is provided in the side wall portion, and the thickness of the opening-facing portion of the side wall portion that faces the opening across the hollow portion is thicker than the thickness of the upper wall portion.

[0009] In this resonance sound absorber, the resonance box has a hollow space surrounded by a bottom wall, an upper wall, and a side wall. The thickness of the opening-facing portion of the side wall, which faces the opening, is thicker than the upper wall. The side wall has a thick opening-facing portion, thereby increasing its rigidity. The resonance sound absorber is mounted so that the bottom wall faces the mounting surface of the tire. In other words, the upper wall can be supported by the side wall, which has a thick opening-facing portion. This makes it possible to suppress deformation of the upper wall even when centrifugal force is applied to the resonance box of the resonance sound absorber as the tire rotates. In this way, this resonance sound absorber can suppress deformation of the resonance box even when centrifugal force is applied.

[0010] A resonance sound absorber according to yet another aspect of the present disclosure is a resonance sound absorber attached to a mounting surface of a tire cavity, and includes a resonance box having an opening and a hollow portion formed therein, the resonance box having a cylindrical main body extending along an axis, a first side wall portion sealing the cylindrical portion opening at one end of the main body in the axial direction, and a second side wall portion sealing the cylindrical portion opening at the other end of the main body in the axial direction, and the main body has a bottom wall portion facing the mounting surface, and a hollow portion formed between the bottom wall portion and the bottom wall portion. and a top wall portion having both ends in a direction perpendicular to the axial direction connected to both ends in the direction perpendicular to the axial direction, respectively, wherein the top wall portion, when viewed along the axis, has a shape that follows a cylindrical surface whose axis is a central axis along the axis, the opening is provided in the first side wall portion, and, when viewed along the axis, is provided at a position closer to the bottom wall portion than the position of the central axis of the cylindrical surface along which the top wall portion follows, and the thickness of the bottom wall portion is thicker than the thickness of an upper wall portion, which is the portion of the top wall portion that faces the bottom wall portion.

[0011] In this resonance sound absorber, the resonance box has a hollow between the bottom wall and the top wall. The bottom wall is thicker than the upper wall of the top wall. The thicker bottom wall increases the rigidity of the resonance box. The upper wall is thinner than the bottom wall, reducing the weight of the upper wall. The resonance sound absorber is attached so that the bottom wall faces the tire mounting surface. That is, the thicker bottom wall faces the tire mounting surface, and the upper wall is positioned above it. As a result, even when centrifugal force is applied to the resonance box of the resonance sound absorber as the tire rotates, the lightweight upper wall can suppress the centrifugal force applied to the upper wall. Therefore, deformation of the top wall of the resonance sound absorber is suppressed. In this way, this resonance sound absorber can suppress deformation of the resonance box even when centrifugal force is applied.

[0012] In the above-described resonance sound absorber, the thickness of the second side wall portion may be thicker than the thickness of the upper wall portion. In this case, the increased thickness of the second side wall portion further increases the rigidity of the resonance box. The thick second side wall portion can support the upper wall portion. This further reduces deformation of the upper wall portion even when centrifugal force is applied to the resonance box of the resonance sound absorber as the tire rotates. In this way, this resonance sound absorber further reduces deformation of the resonance box even when centrifugal force is applied.

[0013] The above-mentioned resonant sound absorber may be inserted into the opening and fixed to the resonance box, and may have a hollow neck portion extending into the hollow portion. In this case, by providing the neck portion, the resonant sound absorber can adjust the frequency of sound absorption.

[0014] In the above-mentioned resonance sound absorber, a bead may be provided on the bottom wall portion, in which case the resonance sound absorber can improve the rigidity of the resonance box.

[0015] In the above-described resonant sound absorber, the beads may have a first bead and a second bead that each protrude toward the hollow portion, the first bead and the second bead extending parallel to each other along the extension direction of the neck portion, and the neck portion may be located between the first bead and the second bead. In this case, the resonant sound absorber can suppress misalignment of the neck portion within the hollow portion by sandwiching the neck portion between the first bead and the second bead.

[0016] In the above-described resonance sound absorber, the resonance box may be provided on the outer surface of the side wall or the first side wall and may have a fixed cylindrical portion that communicates with the opening, and the neck portion may be inserted into the fixed cylindrical portion and the opening and fixed to the fixed cylindrical portion. In this case, the neck portion of the resonance sound absorber can be easily fixed to the resonance box using the fixed cylindrical portion.

[0017] According to one aspect of the present disclosure, deformation of the resonance box can be suppressed even when centrifugal force is applied.

[0018] FIG. 1 is a schematic cross-sectional view of a tire to which a sound absorbing unit according to an embodiment is attached. FIG. 2 is a schematic perspective view of the sound absorbing unit according to an embodiment, viewed from the open side. FIG. 3 is a schematic front view of the sound absorbing unit according to an embodiment, viewed from the open side. FIG. 4 is a schematic side view for explaining the orientation of a support body attached to the mounting surface of a tire. FIG. 5 is a schematic perspective view of the resonance sound absorber of FIG. 2, viewed from the open side. FIG. 6 is a schematic perspective view of the resonance sound absorber of FIG. 2, viewed from the flat portion side. FIG. 7 is a schematic front view of the resonance sound absorber of FIG. 2, viewed from the open side. FIG. 8 is a schematic cross-sectional view of the resonance sound absorber of FIG. 2, cut along the axis. FIG. 9 is a schematic cross-sectional view of the resonance sound absorber of FIG. 2, cut along a direction perpendicular to the axis.

[0019] Hereinafter, with reference to the drawings, an embodiment of a sound absorbing unit equipped with a resonance sound absorber according to the present disclosure will be described in detail. Note that in the drawings, the same or corresponding parts are designated by the same reference numerals, and duplicate explanations will be omitted. Furthermore, numerical ranges indicated using "to" indicate ranges that include the numerical values ​​before and after "to" as the minimum and maximum values, respectively.

[0020] FIG. 1 is a schematic cross-sectional view of a tire equipped with a sound-absorbing unit 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 cavity resonance frequency is, for example, approximately 180 Hz to 250 Hz. The cavity resonance frequency varies depending on factors such as the size of the tire T. The sound-absorbing unit 100 according to this embodiment is attached to a mounting surface Ta of the cavity S of the tire T in order to efficiently absorb cavity resonance in the low-frequency band. The mounting surface Ta is the inner circumferential surface of the tread Tb of the tire T.

[0021] In this embodiment, four sound absorbing units 100 are provided within the cavity S of the tire T. In this embodiment, the four sound absorbing units 100 are attached to the attachment surface Ta at positions offset by 90° in the rotational direction of the tire T. However, the number and attachment positions of the sound absorbing units 100 are not limited to the configuration shown in FIG. 1 . Furthermore, the sound absorbing units 100 may be attached within the cavity S of the tire T in combination with other functional components such as a power generation device, sensor device, secondary battery, capacitor, antenna device, transmitter, processor, memory, and circuit, as needed. In this case, it is preferable to attach the sound absorbing units 100 in an appropriate position so that the weight within the tire T is uniform, taking into consideration the weight and number of the attached functional components and sound absorbing units 100.

[0022] A sound absorbing unit 100 according to an embodiment will be described with reference to Figures 2 and 3. Figure 2 is a schematic perspective view of the sound absorbing unit according to the embodiment, viewed from the open side. Figure 3 is a schematic front view of the sound absorbing unit according to the embodiment, viewed from the open side. As shown in Figures 2 and 3, the sound absorbing unit 100 includes a resonance sound absorber 1 and a support body 5. The resonance sound absorber 1 has a Helmholtz resonance structure. The resonance sound absorber 1 absorbs cavity resonance within the inner cavity S of the tire T. The resonance sound absorber 1 has a shape that extends along the axis L1. In other words, the resonance sound absorber 1 has a generally rod-like shape with the axis L1 as its longitudinal direction.

[0023] The support body 5 is attached to the mounting surface Ta of the tire T. The support body 5 supports the resonance sound absorber 1 against the mounting surface Ta. In this embodiment, as an example, three support bodies 5 are provided. The three support bodies 5 are arranged side by side along the axis L1. The three support bodies 5 have the same shape. The resonance sound absorber 1 is supported against the mounting surface Ta by the three support bodies 5. However, the number of support bodies 5 supporting the resonance sound absorber 1 is not limited to three.

[0024] The support body 5 includes a device mounting portion 50, a first base portion 51a, a second base portion 51b, a first leg portion 52a, and a second leg portion 52b. The resonant sound absorber 1 is mounted to the device mounting portion 50. In this embodiment, the device mounting portion 50 is annular. The device mounting portion 50 surrounds and holds the resonant sound absorber 1. The device mounting portion 50 is elastically deformable. The device mounting portion 50 can detachably hold the resonant sound absorber 1 by its elastic force.

[0025] The device mounting portion 50 includes a holding portion 50X and a spaced portion 50Y. In this embodiment, two holding portions 50X and two spaced portions 50Y are provided. The holding portions 50X and the spaced portions 50Y are alternately arranged in the circumferential direction of the annular device mounting portion 50. The holding portion 50X is a portion of the device mounting portion 50 where the inner surface 50a of the device mounting portion 50 abuts against the outer surface 10a of the resonance box 10 of the resonant sound absorber 1. The spaced portion 50Y is a portion of the device mounting portion 50 where the inner surface 50a of the device mounting portion 50 is spaced from the outer surface 10a of the resonance box 10 of the resonant sound absorber 1. The inner surface 50a of the device mounting portion 50 is the inner circumferential surface of the annular device mounting portion 50.

[0026] Fig. 4 is a schematic side view illustrating the orientation of the support body attached to the mounting surface of the tire. Note that in Fig. 4, in order to show the orientation of the device mounting portion 50, only one device mounting portion 50 is shown, and the resonance sound absorber 1 is omitted. Also, as shown in Fig. 4, the perpendicular line to the mounting surface Ta of the tire T is defined as perpendicular line K1. A line perpendicular to perpendicular line K1 is defined as reference line K2. Note that reference line K2 is parallel to the width direction of the tire T. In other words, reference line K2 is parallel to the rotational center line of the tire T.

[0027] 4, the annular device mounting portion 50 is supported by the first leg 52a and the second leg 52b so as to surround a reference line K2 that is perpendicular to the normal K1 of the inner surface 50a. In other words, the annular device mounting portion 50 is supported so as to stand up from the mounting surface Ta. The opening of the annular device mounting portion 50 does not face the mounting surface Ta.

[0028] 2 and 3 , the first base portion 51 a and the second leg portion 52 b are each attached to the mounting surface Ta of the tire T. The first base portion 51 a and the second leg portion 52 b are attached to the mounting surface Ta by, for example, double-sided tape with adhesive surfaces on both sides, adhesive, welding, or the like.

[0029] 3, a sealant layer F may be provided on the mounting surface Ta of the tire. This sealant layer F may have the function of sealing holes in the tire T to prevent punctures of the tire T, for example. In this case, the first base portion 51a and the like are attached to the sealant layer F provided on the mounting surface Ta. That is, the first base portion 51a and the like are attached to the mounting surface Ta via the sealant layer F. The first base portion 51a and the like are attached to the sealant layer F, for example, with an adhesive. Furthermore, the first base portion 51a and the like may be placed on the sealant layer F when the sealant layer F is cured, and may be adhered to the sealant layer F by curing the sealant layer F.

[0030] In this way, attaching the first base portion 51a etc. to the mounting surface Ta includes attaching the first base portion 51a etc. directly to the mounting surface Ta, and attaching the first base portion 51a etc. to the mounting surface Ta via a member such as a sealant layer F.

[0031] The first leg 52a connects the first base portion 51a and the device mounting portion 50. The first leg 52a stands up from the first base portion 51a. The second leg 52b connects the second base portion 51b and the device mounting portion 50. The second leg 52b stands up from the second base portion 51b. The first leg 52a and the second leg 52b support the device mounting portion 50 so that the device mounting portion 50 is spaced apart from the mounting surface Ta when the first base portion 51a and the second base portion 51b are attached to the mounting surface Ta of the tire T. In other words, the first leg 52a and the second leg 52b support the device mounting portion 50 so as to lift it up from the mounting surface Ta of the tire T.

[0032] As described above, the device mounting portion 50 has two spaced apart portions 50Y. The two spaced apart portions 50Y are spaced apart from each other in the circumferential direction of the annular device mounting portion 50. The first leg portion 52a is connected to the outer surface 50b of the device mounting portion 50 at one of the spaced apart portions 50Y. The second leg portion 52b is connected to the outer surface 50b of the device mounting portion 50 at the other of the spaced apart portions 50Y. In this manner, the first leg portion 52a and the second leg portion 52b extend from each of the two spaced apart portions 50Y toward the first base portion 51a and the second base portion 51b, respectively.

[0033] The first base portion 51a protrudes from the end of the first leg portion 52a toward the opposite side to the second base portion 51b. The second base portion 51b protrudes from the end of the second leg portion 52b toward the opposite side to the first base portion 51a.

[0034] The material of the support body 5 may be, for example, a dynamically crosslinked thermoplastic elastomer (TPV) or vulcanized rubber such as styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), butadiene rubber (BR), chloroprene rubber (CR), and isoprene rubber (IR). By using these materials, a support body 5 having excellent elasticity, heat resistance, and flexibility and suitable as a supporting member within the cavity S of the tire T can be obtained.

[0035] However, the material of the support 5 is not limited to these. In addition, the material of the support 5 may be a thermoplastic elastomer other than the dynamically crosslinked thermoplastic elastomer (TPV) (for example, a styrene-based elastomer (TPS), a polyolefin-based elastomer (TPO), a polyurethane-based elastomer (TPU), a polyester-based elastomer (TPEE), a polyester-based elastomer (TPC), etc.). Furthermore, the material of the support 5 may be various foam materials (for example, foamed rubber, foamed urethane, etc.).

[0036] As shown in Figures 2 and 3, the resonance sound absorber 1 includes a resonance box 10 and a neck portion 20. The resonance sound absorber 1 will be described in detail below. Figure 5 is a schematic perspective view of the resonance sound absorber of Figure 2, viewed from the open side. Figure 6 is a schematic perspective view of the resonance sound absorber of Figure 2, viewed from the flat portion side. Figure 7 is a schematic front view of the resonance sound absorber of Figure 2, viewed from the open side. Figure 8 is a schematic cross-sectional view of the resonance sound absorber of Figure 2, taken along the axis. Figure 9 is a schematic cross-sectional view of the resonance sound absorber of Figure 2, taken along a direction perpendicular to the axis. Figure 9 is also a cross-sectional view taken along line IX-IX in Figure 8.

[0037] As shown in each drawing, the direction along the axis L1 (axis L1 direction) is defined as the first direction D1, the direction perpendicular to the first direction D1 is defined as the second direction D2, and the direction perpendicular to the first direction D1 and the second direction D2 is defined as the third direction D3. The first direction D1 is the axis L1 direction. The second direction D2 is also an orthogonal direction perpendicular to the axis L1 direction. The third direction D3 is also the height direction of the resonance box 10. When the resonance sound absorber 1 is attached to the mounting surface Ta of the tire T by the support body 5, the third direction D3 is also the direction along the perpendicular line K1 to the mounting surface Ta.

[0038] 5 to 9, the resonance box 10 of the resonance sound absorber 1 has a hollow portion R formed therein (see FIG. 8). The resonance box 10 has an opening 10b that connects the hollow portion R with the external space (see FIG. 8). The resonance box 10 has a main body 11, a first side wall 12, a second side wall 13, and a fixed cylinder 16 (see FIG. 8).

[0039] The main body 11 has a cylindrical shape extending in a first direction D1 along the axis L1. The first side wall 12 has a plate shape. The first side wall 12 seals a cylindrical opening 11a (see FIG. 8) at one end of the main body 11 in the first direction D1. The first side wall 12 has an opening 10b. The second side wall 13 has a plate shape. The second side wall 13 seals a cylindrical opening 11b (see FIG. 8) at the other end of the main body 11 in the first direction D1. The second side wall 13 faces the opening 10b provided in the first side wall 12. In this way, the resonance box 10 has a shape in which the portions other than the opening 10b are closed.

[0040] The cylindrical main body 11 has a flat portion (bottom wall portion) 14 and a top wall portion 15. The flat portion 14 is generally plate-shaped. The flat portion 14 is formed in a generally rectangular plate shape that is long in the first direction D1 and short in the second direction D2. The flat portion 14 faces the mounting surface Ta of the tire T. The resonance sound absorber 1 is attached to the device mounting portion 50 of the support body 5 so that the flat portion 14 of the resonance box 10 faces the mounting surface Ta when the sound absorbing unit 100 is attached to the mounting surface Ta of the tire T. Specifically, the resonance sound absorber 1 is attached to the device mounting portion 50 so that the flat portion 14 of the resonance box 10 faces the first base portion 51 a and the second base portion 51 b.

[0041] The top wall portion 15 forms a hollow portion R between itself and the flat portion 14. The top wall portion 15 covers the hollow portion R from the side opposite the flat portion 14. Both ends of the top wall portion 15 in the second direction D2 (ends 15a and 15b) are connected to both ends of the flat portion 14 in the second direction D2 (ends 14a and 14b) (see FIG. 9 ). The top wall portion 15 is curved in an arc shape when viewed along the first direction D1.

[0042] More specifically, as shown in Fig. 9, when viewed along the axis L1 (first direction D1), the top wall portion 15 has a shape that follows a cylindrical surface M whose axis is a central axis L2 that follows the axis L1. The cylindrical surface M whose axis is the central axis L2 is a cylindrical surface that surrounds the central axis L2 and is centered on the central axis L2. However, the shape of the top wall portion 15 is not limited to being completely along the cylindrical surface M. The top wall portion 15 may have any shape that is close to a shape that follows the cylindrical surface M.

[0043] 7 and 8 , opening 10b provided in first side wall portion 12 is located closer to flat portion 14 than the position of center axis L2 of cylindrical surface M along which top wall portion 15 extends, when viewed along axis L1 (first direction D1). In other words, opening 10b is located near the edge of first side wall portion 12 on the side connected to flat portion 14. Opening 10b is located closer to the edge of first side wall portion 12 connected to flat portion 14 than the edge connected to top wall portion 15.

[0044] Here, the shape of the resonance box 10 can also be expressed as follows. As shown in FIGS. 7 and 8 , the resonance box 10 has a flat portion 14, an upper wall portion 15c, and a side wall portion 17. The upper wall portion 15c faces the flat portion 14 and forms a hollow portion R between itself and the flat portion 14. The upper wall portion 15c is disposed a predetermined distance away from the flat portion 14. The upper wall portion 15c is a portion of the top wall portion 15 that faces the flat portion 14 across the central axis L2. The upper wall portion 15c and the flat portion 14 face each other in the third direction D3. In other words, the upper wall portion 15c is formed by a part of the top wall portion 15. The upper wall portion 15c is a portion of the top wall portion 15 that faces the flat portion 14.

[0045] The side wall portion 17 is disposed between the flat portion 14 and the upper wall portion 15c so as to surround the hollow portion R. The side wall portion 17 rises from the edge of the flat portion 14 to surround the hollow portion R from the side, and is connected to the edge of the upper wall portion 15c. The side wall portion 17 is formed by the first side wall portion 12, the second side wall portion 13, and a portion of the top wall portion 15. This portion of the top wall portion 15 is the portion of the top wall portion 15 other than the upper wall portion 15c.

[0046] The opening 10b is provided in the side wall 17 (first side wall 12). In the side wall 17 surrounding the hollow portion R, a portion facing the opening 10b is referred to as an opening facing portion 17a (see FIG. 8). The opening facing portion 17a is a portion of the side wall 17 facing the opening 10b across the hollow portion R. The opening facing portion 17a is formed by the second side wall 13.

[0047] The thickness of the resonance box 10 has the following configuration. The thickness of the flat portion 14 is thicker than the thickness of the upper wall portion 15c of the top wall portion 15 that faces the flat portion 14. For example, the thickness of the flat portion 14 may be 1.1 times or more the thickness of the upper wall portion 15c of the top wall portion 15. For example, the thickness of the top wall portion 15 may be approximately 0.4 mm or less. Furthermore, the thickness of the opening-facing portion 17a (i.e., the second side wall portion 13) is thicker than the thickness of the upper wall portion 15c of the top wall portion 15. For example, the thickness of the opening-facing portion 17a may be 1.1 times or more the thickness of the upper wall portion 15c of the top wall portion 15.

[0048] The flat portion 14 is provided with a first bead (bead) 14c and a second bead (bead) 14d extending along the first direction D1 (axis L1). The first bead 14c and the second bead 14d extend parallel to each other along the first direction D1 (extending direction of the neck portion 20). The first bead 14c and the second bead 14d provided on the flat portion 14 protrude toward the hollow portion R (inside the resonance box 10). As shown in FIG. 9 , for example, the first bead 14c protrudes toward the hollow portion R so that a cross section cut along a direction perpendicular to the axis L1 has a substantially arc-shaped cross section. Similar to the first bead 14c, the second bead 14d also protrudes toward the hollow portion R so that it has a substantially arc-shaped cross section. However, the shapes of the first bead 14c and the second bead 14d are not limited to a substantially arc-shaped cross section and may have other shapes. The first bead 14c and the second bead 14d may have any shape as long as they protrude toward the hollow portion R.

[0049] As shown in FIG. 8 , the fixed cylinder portion 16 is provided on the outer surface of the first side wall portion 12 (side wall portion 17). The outer surface of the first side wall portion 12 is the surface facing outward in the resonance box 10. In other words, the outer surface of the first side wall portion 12 is also part of the outer surface 10a of the resonance box 10. The fixed cylinder portion 16 has a cylindrical shape. In the present embodiment, the fixed cylinder portion 16 has a cylindrical shape, for example. The fixed cylinder portion 16 communicates with an opening 10b provided in the first side wall portion 12. As a result, the hollow portion R within the resonance box 10 and the external space communicate with each other via the opening 10b provided in the first side wall portion 12 and the fixed cylinder portion 16.

[0050] The neck portion 20 is disposed within the resonance box 10. In this embodiment, the entire tube main body portion 21 of the neck portion 20 is disposed within the resonance box 10. However, the base end 20a of the neck portion 20 may extend outward from the resonance box 10 (here, the fixed tube portion 16). A hollow portion 20c is formed inside the neck portion 20. The base end 20a and the tip end 20b of the neck portion 20 are open ends that expose the hollow portion 20c.

[0051] The neck portion 20 has a tube main body portion 21 and a folded portion 22. The tube main body portion 21 has a tubular shape with a hollow portion 20c formed inside. In the present embodiment, the tube main body portion 21 has a cylindrical shape, as an example. The folded portion 22 has a cylindrical shape. The folded portion 22 is arranged at the base end 20a of the neck portion 20 so as to surround the tube main body portion 21. In the present embodiment, the folded portion 22 has a cylindrical shape, as an example. A predetermined gap is provided between the outer peripheral surface of the tube main body portion 21 and the inner peripheral surface of the folded portion 22. The tube main body portion 21 and the folded portion 22 are connected to each other at the base end 20a of the neck portion 20. The fixed tube portion 16 of the resonance box 10 can be inserted into the gap between the outer peripheral surface of the tube main body portion 21 and the inner peripheral surface of the folded portion 22.

[0052] The neck portion 20 is inserted into the fixed cylinder portion 16 and the opening 10b of the resonance box 10 and fixed to the resonance box 10, and extends into the hollow portion R of the resonance box 10. In other words, the tip 20b of the neck portion 20 is located within the hollow portion R. The neck portion 20 is inserted so as to extend in a direction along the axis L1. As a result, the hollow portion R of the resonance box 10 and the external space communicate with each other via the hollow portion 20c of the neck portion 20.

[0053] The neck portion 20 is inserted into the fixed cylinder portion 16 of the resonance box 10 and the opening 10b so that the fixed cylinder portion 16 of the resonance box 10 fits into the gap between the outer circumferential surface of the cylinder main body portion 21 and the inner circumferential surface of the folded portion 22. In other words, the cylinder main body portion 21 of the neck portion 20 is inserted into the fixed cylinder portion 16 of the resonance box 10 and the opening 10b. The neck portion 20 is fixed to the fixed cylinder portion 16 of the resonance box 10. The neck portion 20 and the fixed cylinder portion 16 of the resonance box 10 are fixed to each other by, for example, engaging a recess with a protrusion, engaging a thread with a thread groove, or by adhesive. There are no particular limitations on the method for fixing the neck portion 20 to the fixed cylinder portion 16 of the resonance box 10.

[0054] As described above, the opening 10b in the first side wall 12 is located close to the flat portion 14. Therefore, the tube main body 21 of the neck portion 20 inserted into the opening 10b in the first side wall 12 is located on or near the surface of the flat portion 14. The tube main body 21 of the neck portion 20 inserted into the resonance box 10 is located between the first bead 14c and the second bead 14d when viewed along the third direction D3 (see FIG. 9 ).

[0055] As described above, the resonance box 10 and the neck portion 20 are separate components in the resonance sound absorber 1. The neck portion 20 is inserted into the fixed cylindrical portion 16 and the opening 10b of the resonance box 10, and is fixed to the fixed cylindrical portion 16 of the resonance box 10. This allows the resonance box 10 and the neck portion 20 to be integrated.

[0056] For example, the resonance box 10 is required to be more rigid than the neck portion 20 so that the hollow portion R is not crushed by centrifugal force when the tire T rotates. Furthermore, the resonance sound absorber 1 is also required to be lightweight overall. Thus, the resonance sound absorber 1 is required to be able to respond to various conditions. In this embodiment, the resonance box 10 and the neck portion 20 of the resonance sound absorber 1 are separate components. Therefore, different materials can be used for the resonance box 10 and the neck portion 20 so that the respective requirements are met. Furthermore, different manufacturing methods can be used for the resonance box 10 and the neck portion 20 so that the respective requirements are met.

[0057] For example, the material forming the resonance box 10 may be a material whose elastic modulus itself is higher than that of the material forming the neck portion 20. This makes it possible to suppress deformation of the resonance box 10. The material forming the resonance box 10 may be a material whose rigidity itself is higher than that of the material forming the neck portion 20. This makes it possible to suppress deformation of the resonance box 10. The material forming the resonance box 10 may be a material whose specific gravity itself is higher than that of the material forming the neck portion 20. This makes it possible to reduce the weight of the neck portion 20.

[0058] For example, the materials of the resonance box 10 and the neck portion 20 may be thermoplastics such as polypropylene (PP), polyethylene terephthalate (PET), polyethylene (PE), polyamide (PA), polycarbonate (PC), polyacetal (POM), polyphenylene sulfide (PPS), etc.; thermoplastic elastomers such as olefin-based (TPO), dynamically crosslinked (TPV), styrene-based (TPS), polyurethane-based (TPU), and polyester-based (TPEE); or vulcanized rubbers such as natural rubber (NR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), butadiene rubber (BR), and chloroprene rubber (CR).

[0059] The resonance box 10 can be manufactured by blow molding, as an example. In this case, the manufacturing method of the resonance box 10 of the resonance sound absorber 1 includes the steps of placing the material (parison) of the resonance box 10 in a mold in which a cavity corresponding to the outer shape of the resonance box 10 is formed, injecting gas into the material to form the resonance box 10 by blow molding, and removing the molded resonance box 10 from the mold. Note that the air blowing port that injects gas into the material in the step of molding the resonance box 10 by blow molding serves as the opening 10b of the resonance box 10. By molding the resonance box 10 by blow molding, the resonance box 10 having the hollow portion R can be easily manufactured.

[0060] As described above, the resonance box 10 is formed by blow molding so as to satisfy various conditions, such as the condition for the position of the opening 10b provided in the first side wall 12, and the condition for the difference in thickness between the flat portion 14 and the opening-facing portion 17a (second side wall 13) and the upper wall 15c of the top wall 15. Specifically, the resonance box 10 having the above-described configuration is obtained by adjusting, for example, the temperature and temperature distribution of the mold, the temperature and temperature distribution of the material of the resonance box 10, the position at which air is supplied into the material placed in the mold (the position that will become the opening 10b), the pressure of the gas supplied into the material placed in the mold, the temperature difference between the mold and the material, the dimensional difference between the mold and the material, the material of the resonance box 10, and the like.

[0061] The neck portion 20 may be manufactured by, for example, injection molding, extrusion molding, 3D printing, salt coagulation, or the like. However, there are no particular limitations on the manufacturing method for the neck portion 20. As such, since the resonance box 10 and the neck portion 20 are separate components, they can be manufactured by different manufacturing methods.

[0062] Next, we will explain the manufacturing method of the resonance sound absorber 1. The manufacturing method of the resonance sound absorber 1 includes the steps of manufacturing the resonance box 10 having the opening 10b and the hollow portion R formed therein, manufacturing the hollow neck portion 20, and inserting the neck portion 20 into the opening 10b of the resonance box 10 and fixing the neck portion 20 to the resonance box 10. In this way, the resonance box 10 and the neck portion 20, which are separate components, are assembled to obtain the resonance sound absorber 1.

[0063] In this resonance sound absorber 1, the resonance box 10 has a hollow portion R surrounded by a flat portion 14, an upper wall portion 15c, and a side wall portion 17. The thickness of the flat portion 14 is thicker than that of the upper wall portion 15c. In other words, the upper wall portion 15c is thinner than the flat portion 14, thereby reducing the weight of the upper wall portion 15c. The resonance sound absorber 1 is attached by the support 5 so that the flat portion 14 faces the mounting surface Ta of the tire T. In other words, the lightweight upper wall portion 15c is positioned above the flat portion 14. As a result, even when centrifugal force is applied to the resonance box 10 of the resonance sound absorber 1 as the tire T rotates, the lightweight upper wall portion 15c can suppress the centrifugal force applied to the upper wall portion 15c. Therefore, deformation of the upper wall portion 15c is suppressed in the resonance sound absorber 1. Furthermore, the increased thickness of the flat portion 14 can increase the rigidity of the resonance box 10. In this way, with this resonance sound absorber 1, deformation of the resonance box 10 can be suppressed even when centrifugal force is applied.

[0064] Furthermore, in the resonance box 10 of this resonance absorber 1, the thickness of the opening-facing portion 17a (second side wall portion 13) of the side wall portion 17 that faces the opening 10b is thicker than the thickness of the upper wall portion 15c. The side wall portion 17 has a thick opening-facing portion 17a, thereby increasing its rigidity. The resonance absorber 1 is attached so that the flat portion 14 faces the mounting surface Ta of the tire T. In other words, the side wall portion 17 having the thick opening-facing portion 17a can support the upper wall portion 15c. This prevents deformation of the upper wall portion 15c even when centrifugal force is applied to the resonance box 10 of the resonance absorber 1 as the tire T rotates. In this way, this resonance absorber 1 prevents deformation of the resonance box 10 even when centrifugal force is applied.

[0065] Furthermore, the resonance box 10 of this resonance sound absorber 1 has a hollow portion R between the flat portion 14 and the top wall portion 15. The thickness of the flat portion 14 is greater than the thickness of the upper wall portion 15c of the top wall portion 15. The greater thickness of the flat portion 14 increases the rigidity of the resonance box 10. Furthermore, the thickness of the upper wall portion 15c is thinner than the flat portion 14, thereby reducing the weight of the upper wall portion 15c.

[0066] The resonance sound absorber 1 is attached by the support 5 so that the flat portion 14 faces the mounting surface Ta of the tire T. In other words, the thick flat portion 14 faces the mounting surface Ta of the tire T, and the upper wall portion 15c of the top wall portion 15 is positioned above it. As a result, even when the tire T rotates and centrifugal force is applied to the resonance box 10 of the resonance sound absorber 1, the lightweight upper wall portion 15c can suppress the centrifugal force applied to the upper wall portion 15c. Therefore, deformation of the top wall portion 15 of the resonance sound absorber 1 is suppressed. In this way, the resonance sound absorber 1 can suppress deformation of the resonance box 10 even when centrifugal force is applied.

[0067] The resonance sound absorber 1 has a neck portion 20 that is inserted into the opening 10b and fixed to the resonance box 10. In this case, by providing the neck portion 20, the resonance sound absorber 1 can adjust the frequency of sound absorption.

[0068] The flat portion 14 of the resonance box 10 is provided with a first bead 14c and a second bead 14d that extend along the extension direction (axis L1 direction) of the neck portion 20. In this case, the resonance sound absorber 1 can improve the rigidity of the resonance box 10.

[0069] The neck portion 20 is located between the first bead 14 c and the second bead 14 d. In this case, the resonant sound absorber 1 can suppress misalignment of the neck portion 20 within the hollow portion R by sandwiching the neck portion 20 between the first bead 14 c and the second bead 14 d.

[0070] The resonance box 10 has a fixed cylindrical portion 16 attached to the outer surface of the first side wall portion 12. The neck portion 20 is inserted into the fixed cylindrical portion 16 and the opening 10b of the resonance box 10 and fixed to the fixed cylindrical portion 16. In this case, the neck portion 20 of the resonance absorber 1 can be easily fixed to the resonance box 10 using the fixed cylindrical portion 16.

[0071] As described above, the resonance box 10 can be molded by blow molding. In blow molding, the farther the air outlet (air hole) for blowing air into the material (parison) of the resonance box 10 is from the center of the resonance box 10 (the greater the eccentricity), the more difficult it is to deliver air to the entire resonance box 10. Specifically, as shown in FIG. 7 , the farther the opening 10b is from the central axis L2 of the top wall 15, the more difficult it is to deliver air into the resonance box 10. For this reason, it is conceivable to position the opening 10b at the central axis L2. However, if the opening 10b is positioned at the central axis L2, the neck portion 20 inserted into the opening 10b will be significantly separated from the inner wall surface of the resonance box 10 and will float within the hollow portion R. If centrifugal force is applied to the neck portion 20 in this state, the neck portion 20 will be significantly deformed.

[0072] Therefore, the main body 11 of the resonance box 10 has a shape including a flat portion 14 and a top wall portion 15. In other words, the main body 11 has a substantially D-shaped cross section. The flat portion 14 is located closer to the central axis L2 of the cylindrical surface M along which the top wall portion 15 extends than the top wall portion 15. The opening 10b provided in the first side wall portion 12 is located closer to the flat portion 14. This allows the flat portion 14 to support the neck portion 20 while positioning the opening 10b closer to the central axis L2. Therefore, the resonance box 10 suppresses deformation of the neck portion 20 with the flat portion 14, and by positioning the opening 10b closer to the central axis L2, it is possible to easily introduce air into the entire resonance box 10 during blow molding.

[0073] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, the resonance sound absorber 1 may be configured without the neck portion 20. Furthermore, the resonance sound absorber 1 is not limited to being attached to the mounting surface Ta of the tire T by the support body 5. For example, the resonance sound absorber 1 may be attached directly to the mounting surface Ta of the tire T.

[0074] The gist of the present disclosure is as follows: [1] A resonance sound absorber to be attached to a mounting surface of a tire cavity, comprising a resonance box having an opening and a hollow portion formed therein, the resonance box having: a bottom wall portion facing the mounting surface, an upper wall portion facing the bottom wall portion and forming the hollow portion between itself and the bottom wall portion, and a side wall portion surrounding the hollow portion between the bottom wall portion and the upper wall portion, wherein the thickness of the bottom wall portion is thicker than the thickness of the upper wall portion. [2] A resonant sound absorber to be attached to a mounting surface of a tire cavity, comprising a resonance box having an opening and a hollow portion formed therein, wherein the resonance box has: a bottom wall portion facing the mounting surface; an upper wall portion facing the bottom wall portion and forming the hollow portion between it and the bottom wall portion; and a side wall portion surrounding the hollow portion between the bottom wall portion and the upper wall portion, wherein the opening is provided in the side wall portion, and the thickness of the opening-facing portion of the side wall portion that faces the opening across the hollow portion is thicker than the thickness of the upper wall portion. [3] A resonant sound absorber attached to a mounting surface of a tire cavity, comprising a resonance box having an opening and a hollow portion formed therein, the resonance box having a cylindrical main body extending along an axis, a first side wall sealing the cylindrical portion opening at one end of the main body in the axial direction, and a second side wall sealing the cylindrical portion opening at the other end of the main body in the axial direction, the main body having a bottom wall facing the mounting surface, and a top wall forming the hollow portion between itself and the bottom wall and having both ends in an orthogonal direction perpendicular to the axial direction connected to both ends of the bottom wall in the orthogonal direction, the top wall having a shape along a cylindrical surface whose axis is along the axis when viewed along the axis, the opening being provided in the first side wall and being provided at a position closer to the bottom wall than the position of the central axis of the cylindrical surface along which the top wall is located when viewed along the axis, A resonant sound absorber in which the thickness of the bottom wall portion is greater than the thickness of an upper wall portion that is a portion of the top wall portion that faces the bottom wall portion.[4] The resonant sound absorber according to [3] above, wherein the thickness of the second side wall portion is greater than the thickness of the upper wall portion. [5] The resonant sound absorber according to any of [1] to [4] above, which is inserted into the opening and fixed to the resonance box, and which includes a hollow neck portion extending into the hollow portion. [6] The resonant sound absorber according to [5] above, wherein a bead is provided on the bottom wall portion. [7] The resonant sound absorber according to [6] above, wherein the bead has a first bead and a second bead each protruding toward the hollow portion, the first bead and the second bead extending parallel to each other along the extension direction of the neck portion, and the neck portion is located between the first bead and the second bead. [8] The resonance sound absorber according to any one of [5] to [7] above, wherein the resonance box is provided on the outer surface of the side wall portion or the first side wall portion and has a cylindrical portion communicating with the opening, and the neck portion is inserted into the cylindrical portion and the opening and fixed to the cylindrical portion.

[0075] 1...resonance sound absorber, 10...resonance box, 10b...opening, 11...main body, 12...first side wall, 13...second side wall (portion facing opening), 14...flat portion (bottom wall), 14c...first bead (bead), 14d...second bead (bead), 15...top wall, 15c...upper wall, 16...fixed tube, 17...side wall, 17a...opening facing portion (second side wall), 20...neck, L1...axis, L2...central axis, R...hollow portion, S...inner cavity, T...tire, Ta...mounting surface.

Claims

1. A resonant sound absorber that is attached to a mounting surface of the inner cavity of a tire, comprising a resonance box that has an opening and a hollow portion formed inside, the resonance box having: a bottom wall portion that faces the mounting surface; an upper wall portion that faces the bottom wall portion and forms the hollow portion between it and the bottom wall portion; and side wall portions that are between the bottom wall portion and the upper wall portion and surround the hollow portion, wherein the thickness of the bottom wall portion is thicker than the thickness of the upper wall portion.

2. A resonant sound absorber that is attached to a mounting surface of the inner cavity of a tire, comprising a resonance box that has an opening and a hollow portion formed inside, the resonance box having: a bottom wall that faces the mounting surface; an upper wall that faces the bottom wall and forms the hollow portion between it and the bottom wall; and a side wall that surrounds the hollow portion between the bottom wall and the upper wall, the opening being provided in the side wall, and the thickness of the opening-facing portion of the side wall that faces the opening across the hollow portion is thicker than the thickness of the upper wall.

3. A resonant sound absorber attached to a mounting surface of a tire cavity, comprising a resonance box having an opening and a hollow portion formed therein, the resonance box having a cylindrical main body extending along an axis, a first side wall sealing the cylindrical portion opening at one end of the main body in the axial direction, and a second side wall sealing the cylindrical portion opening at the other end of the main body in the axial direction, the main body having a bottom wall facing the mounting surface, and a top wall forming the hollow portion between itself and the bottom wall and having both ends in an orthogonal direction perpendicular to the axial direction connected to both ends of the bottom wall in the orthogonal direction, the top wall having a shape that follows a cylindrical surface whose axis is a central axis along the axis when viewed along the axis, the opening being provided in the first side wall and being provided at a position closer to the bottom wall than the position of the central axis of the cylindrical surface along which the top wall is located when viewed along the axis, A resonant sound absorber in which the thickness of the bottom wall portion is greater than the thickness of an upper wall portion that is a portion of the top wall portion that faces the bottom wall portion.

4. A resonant sound absorber according to claim 3, wherein the thickness of the second side wall portion is greater than the thickness of the upper side wall portion.

5. A resonant sound absorber according to any one of claims 1 to 4, which is inserted into the opening and fixed to the resonance box, and which has a hollow neck portion extending into the hollow portion.

6. The resonant sound absorber according to claim 5, wherein the bottom wall portion is provided with a bead.

7. A resonant sound absorber as described in claim 6, wherein the bead has a first bead and a second bead each protruding toward the hollow portion, the first bead and the second bead extending parallel to each other along the extension direction of the neck portion, and the neck portion being located between the first bead and the second bead.

8. A resonant sound absorber as described in claim 5, wherein the resonance box is provided on the outer surface of the side wall portion or the first side wall portion and has a cylindrical portion that communicates with the opening, and the neck portion is inserted into the cylindrical portion and the opening and fixed to the cylindrical portion.

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