Tire

Abstract

The present disclosure relates to a tire in which: a meandering groove extending in a tire circumferential direction is formed on a tread surface; a groove width of the meandering groove in a tire width direction varies along the tire circumferential direction at a predetermined repeating cycle; a ratio Wmin / Wmax of a maximum width and a minimum width of the groove width is 0.35 to 0.85; a first groove wall and a second groove wall, which are two groove walls of the meandering groove, each extend in a sinusoidal meandering manner in a tread surface view with the predetermined repeating cycle as a cycle length; and a first sinusoidal curve formed by the first groove wall and a second sinusoidal curve formed by the second groove wall are arranged with a phase difference of 1 / 8 to 3 / 8 of a cycle in the tire circumferential direction in the tread surface view.

Description

Technical Field

[0001] This disclosure relates to tires. Background Technology

[0002] Various methods have been used to improve the drainage performance of pneumatic tires (hereinafter referred to as "tire") that allow water to enter between the road surface and the tread surface in order to suppress wet skidding. Patent Document 1 discloses a tire that can improve drainage performance while preventing deterioration of braking performance.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2011-168222 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] In the tire disclosed in Patent Document 1, the main groove, which serves as the circumferential groove extending along the tire's circumference, has a predetermined shape. This allows the tire disclosed in Patent Document 1 to improve water drainage performance while preventing deterioration of braking performance. However, even with the circumferential groove in the tire described in Patent Document 1, there is still room for improvement in further suppressing air column resonance noise.

[0008] Therefore, the purpose of this disclosure is to provide a tire with meandering grooves on the tread surface, which can improve drainage performance and suppress air column resonance noise while preventing deterioration of braking performance.

[0009] Solution for solving the problem

[0010] The tire, as a first aspect of this disclosure, is a tire having a meandering groove formed on the tread surface extending along the tire circumference, wherein the meandering groove has a groove width in the tire width direction, the groove width varying along the tire circumference at a predetermined repeating period, and when the maximum width of the groove is Wmax and the minimum width of the groove is Wmin, the ratio of the maximum width to the minimum width, Wmin / Wmax, is 0.35 to 0.85, and the first groove wall and the second groove wall, which are the two groove walls of the meandering groove, both extend in a sinusoidal meandering pattern in a tread surface view with the predetermined repeating period as one cycle length, and in the tread surface view, the first sinusoidal curve formed by the first groove wall and the second sinusoidal curve formed by the second groove wall are configured with a phase difference of 1 / 8 to 3 / 8 of the cycle in the tire circumference direction.

[0011] The effects of the invention

[0012] This disclosure provides a tire with meandering grooves on the tread surface, which can improve drainage performance and suppress air column resonance noise while preventing deterioration of braking performance. Attached Figure Description

[0013] [ Figure 1 ] Figure 1 This is a cross-sectional view of a tire in the tire width direction, as an embodiment of this disclosure.

[0014] [ Figure 2 ] Figure 2 yes Figure 1 The diagram shows a partial unfolded view of the tire tread surface.

[0015] [ Figure 3 ] Figure 3 yes Figure 2 An enlarged view of a meandering groove on the tire tread surface.

[0016] [ Figure 4 ] Figure 4 This is an explanation Figure 3 A diagram illustrating the reflection of a portion of the sound waves within the meandering groove.

[0017] [ Figure 5 ] Figure 5 A meandering groove is shown as a comparative example.

[0018] [ Figure 6 ] Figure 6 A Helmholtz resonator with a single, narrow outer neck is schematically shown. Detailed Implementation

[0019] The following is an illustrative explanation of embodiments of a tire according to the present disclosure, with reference to the accompanying drawings. In the figures, common components are labeled with the same reference numerals. In this document, the tire width direction refers to the direction parallel to the tire's axis of rotation. The tire radial direction refers to the radial direction orthogonal to the tire's axis of rotation and centered on the axis of rotation. The tire circumferential direction refers to the direction in which the tire rotates about its axis of rotation.

[0020] In this document, the term "tread surface" refers to the outer peripheral surface of the tire that contacts the road surface when the tire is mounted on a rim, filled with a specified internal pressure, and rolling under maximum load (hereinafter also referred to as "maximum load condition"). Furthermore, the term "tread end" refers to the outer edge of the tread surface in the tire width direction.

[0021] As used herein, the term "rim" refers to a standard rim of applicable size (measured rim in the ETRTO Standards Manual and designed rim in the TRA Yearbook) that is recorded or will be recorded in an industry standard in effect in the region where the tire is manufactured and used. Such industry standards include, for example, the JATMA Yearbook of Japan's JATMA (Japan Automobile Tire Manufacturers Association), the standards manual of ETRTO (European Tire & Rim Technology Organization) in Europe, and the yearbook of TRA (Tire & Rim Association) in the United States. For sizes not listed in these industry standards, the term "rim" refers to a rim whose width corresponds to the width of the tire's bead. "Rim" includes both current and future sizes that may be included in the aforementioned industry standards. Examples of "sizes to be recorded in the future" include sizes described as "FUTURE DEVELOPMENTS" in the 2013 edition of the ETRTO Standards Manual.

[0022] As used herein, "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity of a single wheel under the applicable size and ply rating specified in the aforementioned industry standards such as the JATMA Yearbook. For sizes not listed in the aforementioned industry standards, "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity specified for each vehicle with the tire mounted. Furthermore, as used herein, the term "maximum load" refers to the load corresponding to the maximum load capacity of a tire of the applicable size specified in the aforementioned industry standards, or, for sizes not listed in the aforementioned industry standards, the load corresponding to the maximum load capacity specified for each vehicle with the tire mounted.

[0023] The following description, with reference to the accompanying drawings, illustrates an embodiment of a pneumatic tire 1 (hereinafter referred to as "tire 1") according to the present disclosure. In this embodiment, a radial tire for a passenger car will be shown as an example of tire 1, but other types of tires may also be used.

[0024] Figure 1 This is a cross-sectional view of tire 1 along its width. For example... Figure 1 As shown, tire 1 includes a pair of bead portions 11, a pair of sidewall portions 12, and a tread portion 13. The sidewall portions 12 are connected to the outer side of the bead portions 11 in the tire radial direction A. The tread portion 13 is connected to the pair of sidewall portions 12. The two ends of the tread portion 13 in the tire width direction B are respectively connected to each sidewall portion 12.

[0025] Each bead portion 11 includes a bead core 11a and a bead filler 11b disposed on the outer side of the bead core 11a in the tire radial direction A. The tire 1 includes a carcass 14 spanning between a pair of bead cores 11a. The carcass 14 is composed of carcass plies, in which cords made of organic fibers or steel are disposed. Furthermore, the tire 1 includes a belt 15 disposed on the outer side of the crown portion of the carcass 14 in the tire radial direction A. The belt 15 is composed of belt plies, in which cords made of organic fibers or steel are disposed. The belt plies constituting the belt 15 may include inclined belt plies, in which the cords are inclined at 10° or greater relative to the tire circumferential direction C. Similarly, the belt plies constituting the belt 15 may also include circumferential belt plies, in which the cords extend along the tire circumferential direction C. Here, the term "cords extending circumferentially along the tire" means that the inclination angle of the cords relative to the tire circumferential direction C is greater than or equal to 0° and less than 10°. Furthermore, the belt 15 may include a plurality of belt ply layers stacked in the tire radial direction A, the plurality of belt ply layers including at least one inclined belt ply layer and at least one circumferential belt ply layer as described above.

[0026] The tire 1 also includes a tread rubber 7 disposed on the outer side of the tire radial direction A of the belt 15 and a sidewall rubber 8 disposed on the outer side of the tire width direction B of the sidewall portion of the tire carcass 14. In addition, the tire 1 includes an inner liner 16 laminated to the inner surface of the tire carcass 14.

[0027] The tire 1 in this embodiment includes the internal structure described above, but the internal structure is not limited. Therefore, the tire 1 may include other internal structures.

[0028] Figure 2 yes Figure 1 The diagram shows a portion of the tread surface T of the tread section 13 of the tire 1. Figure 2 As shown, in this embodiment, circumferential grooves 21 to 24 extending along the tire circumferential direction C are formed on the tread surface T. These circumferential grooves 21 to 24 are unterminated annular grooves along the tire circumferential direction C. The four circumferential grooves 21 to 24 in this embodiment consist of two outer circumferential grooves 21 and 24 and two inner circumferential grooves 22 and 23. The outer circumferential grooves 21 and 24 are the two outermost grooves on both sides in the tire width direction B, and the inner circumferential grooves 22 and 23 are located inside the two outer circumferential grooves 21 and 24 in the tire width direction B. Here, the inner side in the tire width direction B refers to the side in the tire width direction B that is close to the tire equatorial plane CL. The outer side in the tire width direction B refers to the side in the tire width direction B that is opposite to the inner side in the tire width direction B and is far away from the tire equatorial plane CL in the tire width direction B.

[0029] like Figure 2As shown, in this embodiment, five land portions 31 to 35 are formed on the tread surface T of the tire 1, defined by the four circumferential grooves 21 to 24 and the two tread ends TE in the tire width direction B. The five land portions 31 to 35 consist of a central land portion 33, two intermediate land portions 32 and 34, and two shoulder land portions 31 and 35. Both "central land portion" and "intermediate land portion" refer to land portions located between the two outermost outer circumferential grooves on both sides of the tire width direction B, and specifically land portions defined between two adjacent circumferential grooves in the tire width direction B. However, "central land portion" refers to a land portion located at a position intersecting the tire equatorial plane CL, while "intermediate land portion" refers to a land portion located at a position not intersecting the tire equatorial plane CL. For ease of explanation, the central land portion 33 and the intermediate land portions 32 and 34 will be simply referred to as "inner land portions 32 to 34" hereinafter unless otherwise specified. The “shoulder land” is the land between the tread end TE and the outermost tire circumferential groove in the tire width direction.

[0030] More specifically, in this embodiment, the central land portion 33 is defined between two inner circumferential grooves 22 and 23. In this embodiment, one intermediate land portion 32 is located on one side of the tire width direction B, separated from the tire equatorial plane CL. Figure 2 The left side of the tire is defined between the outer circumferential groove 21 and the inner circumferential groove 22. In this embodiment, another intermediate land portion 34 is located on the other side of the tire width direction B, separated from the tire equatorial plane CL. Figure 2 (The right side of the tire) and is defined between the outer circumferential groove 24 and the inner circumferential groove 23. In this embodiment, the inner land portions 32 to 34 are all composed of rib-shaped land portions, which are not divided in the circumferential direction C but are connected in the entire tire circumferential direction C.

[0031] In addition, a shoulder land portion 31 is located on one side of the tire width direction B, separated from the tire equatorial plane CL. Figure 2 The left side of the tire is defined between the tread end TE and the outer circumferential groove 21. The other shoulder-side land portion 35 is located on the other side of the tire width direction B, separated from the tire equatorial plane CL. Figure 2 (on the right side) and is confined between the tread end TE and the outer circumferential groove 24.

[0032] As will be described in detail later, such as Figure 2 As shown, in this embodiment, each of the two intermediate land sections 32 and 34 is provided with a resonator 70, which includes an air chamber 71 and an outer narrow neck 72. Each intermediate land section 32 and 34 is provided with a plurality of resonators 70 spaced apart at predetermined intervals along the tire circumference C.

[0033] like Figure 2As shown, in this embodiment, both shoulder land portions 31 and 35 are provided with a plurality of width-direction grooves 40. The width-direction grooves 40 are not limited to grooves parallel to the tire width direction B, but can also be grooves inclined relative to the tire width direction B at a predetermined angle or less (e.g., 30° or less). In each of the two shoulder land portions 31 and 35, the plurality of width-direction grooves 40 are arranged at predetermined intervals in the tire circumferential direction C. The width-direction grooves 40 extend through the entire area of ​​each shoulder land portion 31 and 35 in the tire width direction B. Therefore, both shoulder land portions 31 and 35 are composed of a plurality of tread block land portions separated in the tire circumferential direction C by the width-direction grooves 40.

[0034] A width-direction groove 40 in one shoulder land portion 31 extends from the tread end TE toward the outer circumferential groove 21. Similarly, a width-direction groove 40 in the other shoulder land portion 35 extends from the tread end TE toward the outer circumferential groove 24.

[0035] More specifically, the outer end of the width-direction groove 40 formed in the shoulder land portions 31 and 35 extends to the tread end TE in the tire width direction B. In particular, in this embodiment, the outer end of the width-direction groove 40 extends beyond the tread end TE to a position outside the tire width direction B of the tread end TE. The inner end of the width-direction groove 40 in the shoulder land portions 31 and 35 opens towards the outer circumferential grooves 21 and 24. In other words, the width-direction groove 40 formed in the shoulder land portion 31 connects to the outer circumferential groove 21 on its inner side in the tire width direction B. Similarly, the width-direction groove 40 formed in the shoulder land portion 35 connects to the outer circumferential groove 24 on its inner side in the tire width direction B.

[0036] The tread surface T of the tire 1 in this embodiment includes four circumferential grooves 21 to 24, but is not limited to this configuration. The tire 1 may have one or more circumferential grooves on the tread surface T. In other words, there is no particular limitation on the number of circumferential grooves formed on the tread surface T of the tire 1, as long as one or more are present. Therefore, the land portions formed on the tread surface T of the tire 1 are not limited to the five land portions 31 to 35 as in this embodiment. In other words, the tread surface T of the tire 1 may be provided with two or more land portions defined by one or more circumferential grooves and the tread ends on both sides in the tire width direction B.

[0037] The construction of each land portion of tire 1 is not limited to this construction. In this embodiment, the shoulder land portions 31 and 35 are provided with a width direction groove 40, but they can be constructed without the width direction groove 40. Similarly, the width direction groove 40 does not necessarily have to intersect each shoulder land portion 31 and 35 in the tire width direction B. In other words, one or both ends of the width direction groove 40 in its extension direction can terminate within each shoulder land portion 31 and 35.

[0038] Furthermore, both intermediate land sections 32 and 34 in this configuration are provided with resonators 70; however, they can be configured without resonators 70. The resonator 70 can be provided in either intermediate land section 32 or 34. For example, the resonator 70 can be provided only in the one of intermediate land sections 32 and 34 that will be located on the inside (vehicle side) when tire 1 is mounted on the vehicle. In this way, it is easier to ensure rigidity relative to the other intermediate land section 32 and 34 that will be located on the outside (opposite to the vehicle side) when tire 1 is mounted on the vehicle during cornering. Furthermore, the resonator 70 can be provided in the central land section 33 or in the shoulder land sections 31 and 35.

[0039] The following will refer to Figure 2 and Figure 3 The meandering groove 20 formed on the tread surface T will be described. In this embodiment, the two inner circumferential grooves 22 and 23 on the tread surface T are formed by the meandering groove 20. Figure 3 yes Figure 2 The image shown is an enlarged view of the inner circumferential groove 22, which is the meandering groove 20. The inner circumferential groove 23, which is the meandering groove 20, has the same construction as the inner circumferential groove 22. In the following text, if there is no particular difference between the two inner circumferential grooves 22 and 23, they will simply be referred to as "meandering groove 20".

[0040] like Figure 2 and Figure 3 As shown, the meandering groove 20 extends along the tire circumferential direction C at the tread surface T. More specifically, in the tread surface view, i.e., the front view at the tread surface T (see... Figure 2 and Figure 3 In the meandering groove 20, the first groove wall 20a and the second groove wall 20b, which are the two groove walls of the tire circumferential direction C, are arranged with a predetermined repeating period λ as a cycle length (see...). Figure 3 It extends in a sinusoidal, meandering pattern. Therefore, as... Figure 3 As shown, the first groove wall 20a and the second groove wall 20b have an amplitude A along the tire width direction B. As detailed below, when viewed from the tread surface, the first sinusoidal curve formed by the first groove wall 20a of the meandering groove 20 and the second sinusoidal curve formed by the second groove wall 20b of the meandering groove 20 have a phase difference in the tire circumferential direction C. The groove bottom 20c of the meandering groove 20 is formed by a flat surface extending along the tire circumferential direction C. It should be noted that the term "sinusoidal" is not limited to a perfect sine wave, but includes a substantially sinusoidal wave. As used herein, a substantially sinusoidal wave is a sine wave whose variation relative to a sine wave obtained as an approximate curve is within ±5% or less. In the tread surface view, the sinusoidal wave as an approximate curve can be, for example, a sine wave approximated by least squares of a curve obtained by tracing the groove wall.

[0041] like Figure 3 As shown, the meandering groove 20 has a groove width W that varies along the tire circumferential direction C with a predetermined repetition period λ. This predetermined repetition period λ is the same as the aforementioned repetition period λ of the first groove wall 20a and the second groove wall 20b of the meandering groove 20, which extend in a sinusoidal pattern in the tread surface view. The groove width W of the meandering groove 20 refers to the distance between the first groove wall 20a and the second groove wall 20b in the tire width direction B. Therefore, the meandering groove 20 includes a wide section 51a and a narrow section 51b.

[0042] Wide section 51a includes the portion where the groove width W reaches its maximum width Wmax. Narrow section 51b includes the portion where the groove width W reaches its minimum width Wmin. Wide section 51a and narrow section 51b are alternately arranged on the tire circumferential direction C.

[0043] Here, the ratio of the maximum width Wmax to the minimum width Wmin of the meandering groove 20, Wmin / Wmax, is between 0.35 and 0.85. For example, in this embodiment, the maximum width Wmax of the groove width W is 9.447 mm. In this embodiment, the minimum width Wmin of the groove width W is 5.967 mm. Therefore, in this embodiment, the ratio of the maximum width Wmax to the minimum width Wmin, Wmin / Wmax, is 0.632.

[0044] In this way, in a tread surface view, the first groove wall 20a and the second groove wall 20b of the meandering groove 20 meander along the tire circumference C, and the groove width W of the meandering groove 20 varies along the tire circumference C with a predetermined repetition period λ. Therefore, water flows in the meandering groove 20 along the meandering of the first groove wall 20a and the second groove wall 20b. In other words, water flows in the meandering groove 20 along the first groove wall 20a and the second groove wall 20b.

[0045] More specifically, the water flowing in the meandering channel 20 flows through a wide section 51a (which includes the portion of the meandering channel 20 where the channel width W reaches its maximum width Wmax), and then flows into a narrow section 51b (which includes the portion of the meandering channel 20 where the channel width W reaches its minimum width Wmin). At this point, as the channel width W of the meandering channel 20 decreases, the water flowing in the meandering channel 20 flows along the first channel wall 20a and the second channel wall 20b. Figure 3 As shown in the tread surface view, the first groove wall 20a and the second groove wall 20b are located along the extension of the line from the wide section 51a to the narrow section 51b (see...). Figure 3The single-dotted arrow in the diagram points to the outer side of the meandering groove 20 in the tire width direction B. Therefore, water flowing in the meandering groove 20 tends to exit from the meandering groove 20 along the extension direction of the first groove wall 20a and the second groove wall 20b as it flows from the wide section 51a to the narrow section 51b. In other words, water flowing in the meandering groove 20 pulsates with a predetermined repetition period λ and tends to drain along the extension direction of the first groove wall 20a and the second groove wall 20b as it flows from the wide section 51a to the narrow section 51b. This improves the drainage performance of water that has entered between the road surface and the tread surface T.

[0046] As described above, by setting the ratio Wmin / Wmax of the maximum width Wmax and the minimum width Wmin of the meandering groove 20 to 0.35 to 0.85, compared to cases where Wmin / Wmax does not fall within the aforementioned range, the recesses of the land portion formed by the first groove wall 20a and the second groove wall 20b extending in a sinusoidal meandering pattern (in this embodiment, the recesses of the sidewalls of the inner land portions 32 to 34) prevent a decrease in the rigidity of the land portion (in this embodiment, the inner land portions 32 to 34). As a result, a decrease in the braking performance of the tire 1 is prevented.

[0047] Furthermore, by setting Wmin / Wmax within the aforementioned range, the improvement in drainage performance can be obtained more reliably. That is, if the value of Wmin / Wmax is less than 0.35, the flow of water along the first channel wall 20a and the second channel wall 20b, as well as the flow of water along the tire circumferential direction C, may easily become excessively concentrated in the narrow section 51b, and the degree of improvement in drainage performance may be smaller. If the value of Wmin / Wmax is greater than 0.85, the water in the meandering channel 20 may be difficult to pulsate, and the degree of improvement in drainage performance may be smaller.

[0048] In addition, such as Figure 2 and Figure 3 As shown in the tread surface view, the first sinusoidal curve formed by the first groove wall 20a of the meandering groove 20 and the second sinusoidal curve formed by the second groove wall 20b are configured with a phase difference of 1 / 8 to 3 / 8 of a cycle in the tire circumferential direction C. Compared to configurations where the phase difference falls outside the aforementioned range, this phase difference can suppress air column resonance noise that can be generated by the meandering groove 20. It should be noted that the term "phase difference of 1 / 8 to 3 / 8 of a cycle in the tire circumferential direction C" refers to a phase difference of 1 / 8 to 3 / 8 of a cycle in any direction in the tire circumferential direction C. Figure 2 and Figure 3 The phase difference in this embodiment shown is 1 / 4 period.

[0049] Figure 4 The dashed arrows L1 and L2 are shown in the diagram. Figure 2 and Figure 3 Some sound waves travel in the meandering groove 20 shown. For example... Figure 4 As shown, the sound wave, represented by the dashed arrow L1, traveling in the meandering groove 20 originates from one end of the tire circumferential C of the meandering groove 20. Figure 4 The upper side of the groove enters the meandering groove 20, is repeatedly reflected by the first groove wall 20a and the second groove wall 20b, and exits from the other end of the meandering groove 20 on the tire circumference C. Figure 4 The sound waves traveling in the meandering groove 20, indicated by the dashed arrow L2, exit from one end of the meandering groove 20 on the tire circumferential C. Figure 4 The upper side of the groove enters the meandering groove 20 and is repeatedly reflected by the first groove wall 20a and the second groove wall 20b, returning to one end of the meandering groove 20 on the tire circumferential C. Figure 4 (The upper side of the groove). In other words, the sound waves traveling in the meandering groove 20, represented by the dashed arrow L2, will not escape from the other end of the tire circumference C of the meandering groove 20. Figure 4 (Leaving from the lower side of the middle). The presence of the sound wave represented by the dashed arrow L2 suppresses the air column resonance sound generated through the meandering groove 20, compared to the absence of the sound wave.

[0050] Figure 5 The meandering grooves 120 and 220 are shown as comparative examples. Specifically, Figure 5 (a) shows a comparative example where the phase difference between the first groove wall 120a and the second groove wall 120b on the tire circumferential C is 1 / 2 period. Figure 5 (b) shows a comparative example where there is no phase difference (a phase difference of 0 periods) between the first groove wall 220a and the second groove wall 220b in the tire circumferential direction C. Figure 5 In (a), some sound waves traveling in the meandering groove 120 are represented by dashed arrows L3 and L4. Figure 5 In (b), some sound waves traveling in the meandering groove 220 are represented by dashed arrows L5 and L6. It is important to note that in... Figure 5 (a) and Figure 5 In (b) shown as a comparative example, the ratio of the maximum width Wmax to the minimum width Wmin, Wmin / Wmax, of the meandering grooves 120 and 220 is in the range of 0.35 to 0.85.

[0051] like Figure 5 As shown in (a), as a comparative example, the sound waves traveling in the meandering groove 120, indicated by dashed arrows L3 and L4, originate from one end of the tire circumferential C of the meandering groove 120. Figure 5 (a) The upper side of the groove enters the meandering groove 120, is repeatedly reflected by the first groove wall 120a and the second groove wall 120b, and exits from the other end of the meandering groove 120 on the tire circumference C. Figure 5(a) below) away. Similarly, as Figure 5 As shown in (b), as a comparative example, the sound waves traveling in the meandering groove 220, indicated by dashed arrows L5 and L6, originate from one end of the tire circumferential C of the meandering groove 220. Figure 5 (b) The upper side of the groove enters the meandering groove 220, is repeatedly reflected by the first groove wall 220a and the second groove wall 220b, and exits from the other end of the meandering groove 220 on the tire circumference C. Figure 5 (b) below) leaving. In this way, respectively as Figure 5 (a) and Figure 5 In the case of the phase difference in the groove walls of the meandering grooves 120 and 220 shown in (b), sound waves can easily escape from one side of the tire circumferential C to the other side.

[0052] Based on the above, by setting a predetermined repetition period λ (see...) Figure 3 By setting the varying groove width W within the range of 0.35 to 0.85 (Wmin / Wmax) and setting the phase difference between the first groove wall 20a and the second groove wall 20b of the meandering groove 20 to the aforementioned 1 / 8 to 3 / 8 period, it is easier to achieve sound waves reflected back from one side of the tire circumferential C rather than escaping to the other side, such as... Figure 4 As indicated by the dashed arrow L2. This enables the creation of a tire 1 with meandering grooves 20, which can improve drainage performance and suppress air column resonance noise while preventing deterioration of braking performance.

[0053] Other features of the tire 1 in this embodiment will be referred to below. Figures 2 to 4 Please provide an explanation.

[0054] First, refer to Figure 3 This will illustrate other features of a meandering groove 20. For example... Figure 3 As shown, the first groove wall 20a and the second groove wall 20b of the meandering groove 20 in this embodiment have an amplitude A along the tire width direction B. More specifically, in the tread surface view, the first sinusoidal curve formed by the first groove wall 20a has an amplitude AP1 along the tire width direction B. Similarly, in the tread surface view, the second sinusoidal curve formed by the second groove wall 20b has an amplitude AP2 along the tire width direction B. Here, in this embodiment, the amplitudes AP1 of the first sinusoidal curve and AP2 of the second sinusoidal curve are equal. Therefore, in this embodiment, in the tread surface view, the maximum amplitude of the first sinusoidal curve and the second sinusoidal curve in the tire width direction B is either the amplitude AP1 of the first sinusoidal curve or the amplitude AP2 of the second sinusoidal curve.

[0055] However, the amplitudes AP1 and AP2 of the first and second sinusoidal curves can be different. In this case, in the tread surface view, the maximum amplitude of the first and second sinusoidal curves in the tire width direction B refers to the larger of the amplitudes AP1 and AP2 of the first and second sinusoidal curves.

[0056] Here, the repetition period λ of the first and second sinusoidal curves (see...) Figure 3 Preferably, the amplitude of the first and second sinusoidal curves in the tire width direction B (in this embodiment, amplitude AP1 or AP2) in the tread surface view is 15 to 100 times greater. With this configuration, water flowing in the meandering groove 20 tends to flow more easily in the direction of the extension of the first groove wall 20a and the second groove wall 20b as it flows from the wide section 51a to the narrow section 51b (see...). Figure 3 The water is drained as it flies out of the meandering trough 20 (as indicated by the dashed arrow in the image). This means that drainage performance can be further improved.

[0057] More specifically, by setting the repetition period λ to 15 times or more the maximum amplitude of the first and second sinusoidal curves, excessive concentration of water flow along the first and second channel walls 20a and 20b, as well as along the tire circumference C, at the narrow section 51b can be prevented. This increases the degree of improvement in drainage performance. Furthermore, by setting the repetition period λ to 100 times or less the maximum amplitude of the first and second sinusoidal curves, the water in the meandering channel 20 is more prone to pulsation, thereby increasing the degree of improvement in drainage performance.

[0058] The contact length, i.e., the length of the tread contact surface that contacts the road surface during tire rolling in the tire circumferential direction C, is preferably 0.5 to 20 times the repetition period λ of the meandering groove 20. By making the contact length at least 0.5 times the repetition period λ of the meandering groove 20, the meandering groove 20 contacts the road surface a sufficient number of times along the tire circumferential direction C during tire rolling to allow for pulsation. This allows water flowing in the meandering groove 20 to be effectively drained to the outside of the meandering groove 20. Similarly, by making the contact length 20 times or less the repetition period λ of the meandering groove 20, water flow along the first groove wall 20a and the second groove wall 20b can easily occur in the meandering groove 20. This allows water flowing in the meandering groove 20 to be effectively drained to the outside of the meandering groove 20.

[0059] It is important to note that the groove depth D of the meandering groove 20 (see...) Figure 1 The groove depth D of the meandering groove 20 in this embodiment is, for example, 8 mm, but it can be shallower or deeper.

[0060] For reference here Figure 2 and Figure 3 The meandering groove 20 on the tread surface T of tire 1 will be explained.

[0061] like Figure 2 As shown, in this embodiment, three or more (four in this embodiment) circumferential grooves 21 to 24 extending along the tire circumferential direction C are formed on the tread surface T. Among the three or more circumferential grooves 21 to 24, one or more (two in this embodiment) inner circumferential grooves 22 and 23, located inside the tire width direction B, are formed by meandering grooves 20.

[0062] In this manner, preferably, the inner circumferential grooves 22 and 23, located closer to the inner side of the tire width direction B than the outer circumferential grooves 21 and 24, are formed by meandering grooves 20. The inner circumferential grooves 22 and 23 tend to have a longer extension length in the tread contact surface than the outer circumferential grooves 21 and 24. The resonance frequency f of the air column resonance sound is expressed by the following (Equation 2). "l" is the extension length in the tread contact surface, "α" is the correction coefficient at the open end of the air column tube, "c" is the speed of sound, and "n" is a natural number.

[0063] f = nc / (2(l+α))……(Equation 1)

[0064] The value “l” in Equation 1 above tends to be larger in the inner circumferential grooves 22 and 23 than in the outer circumferential grooves 21 and 24.

[0065] Furthermore, by forming the inner circumferential grooves 22 and 23 with the meandering groove 20, the distance traveled by sound waves exiting the inner circumferential grooves 22 and 23 from one side to the other along the tire circumferential C is increased within the inner circumferential grooves 22 and 23. This is because the sound waves are repeatedly reflected by the first groove wall 20a and the second groove wall 20b in the meandering groove 20, thereby increasing the travel distance of the sound waves compared to a circumferential groove where the groove walls extend straight along the tire circumferential C. Therefore, by using the meandering groove 20, the same effect as the state where the value "l" in (Equation 1) increases can be obtained.

[0066] In short, the inner circumferential grooves 22 and 23 tend to have a longer extension length in the tread contact area than the outer circumferential grooves 21 and 24. Therefore, the value "l" in the above (Equation 1) tends to be larger in the inner circumferential grooves 22 and 23 than in the outer circumferential grooves 21 and 24. Consequently, based on the above (Equation 1), the resonance frequency f of the inner circumferential grooves 22 and 23 is likely to be smaller than the resonance frequency f of the outer circumferential grooves 21 and 24. As described above, by using these inner circumferential grooves 22 and 23 as meandering grooves 20, an effect even larger than the value "l" in the above (Equation 1) can be achieved. In other words, the resonance frequency f of the inner circumferential grooves 22 and 23 can be further reduced. This makes it easier to promote the dispersion of resonance frequencies in the multiple circumferential grooves 21 to 24 and achieve a reduction in the sound pressure peak value in all circumferential grooves 21 to 24.

[0067] In this embodiment, both inner circumferential grooves 22 and 23 are formed by meandering grooves 20, but only one of them may be formed by meandering grooves 20. However, in the inner circumferential grooves located between the two outer grooves 21 and 24, preferably, the innermost inner circumferential groove located in the tire width direction B (both inner circumferential grooves 22 and 23 in this embodiment) is formed by meandering grooves 20, and more preferably, all inner circumferential grooves (only the two inner circumferential grooves 22 and 23 in this embodiment) are formed by meandering grooves 20. This is also true even when there are three or more inner circumferential grooves. In this way, it is easier to promote the dispersion of resonant frequencies in the multiple circumferential grooves 21 to 24, and it is easier to achieve a reduction in the sound pressure peak value in all circumferential grooves 21 to 24.

[0068] like Figure 2 As shown, in the tread surface view, the outer circumferential grooves 21 and 24 preferably extend in a straight line along the tire circumferential direction C. For ease of explanation, the circumferential grooves extending in a straight line along the tire circumferential direction C in the tread surface view will be referred to as "straight grooves" in the following text. By making the outer circumferential grooves 21 and 24 straight grooves, compared with the configuration where the outer circumferential grooves are meandering grooves 20, the width of each tread block land portion of the shoulder land portions 31 and 35 in the tire width direction B does not change in the tire circumferential direction C. Therefore, the variation in the compressive stiffness of each tread block land portion of the shoulder land portions 31 and 35 in the tire circumferential direction C can be prevented. Therefore, vibration and noise caused by the variation in the compressive stiffness of each tread block land portion of the shoulder land portions 31 and 35 in the tire circumferential direction C can be suppressed. In other words, the influence of axial force variation can be reduced.

[0069] From another perspective, such as Figure 2As shown, in this embodiment, the inner circumferential grooves 22 and 23 adjacent to the outer circumferential grooves 21 and 24 are formed by meandering grooves 20, and a resonator 70 is provided in the land portion (in this embodiment, the intermediate land portion 32 and 34) defined between the outer circumferential grooves 21 and 24 and the inner circumferential grooves 22 and 23 adjacent to the outer circumferential grooves 21 and 24 formed by meandering grooves 20.

[0070] The resonator 70 is a Helmholtz resonator having an air chamber 71 and one or more outer narrow necks 72. The air chamber 71 opens to the tread surface of the land portion. The outer narrow necks 72 connect the air chamber 71 to the outer circumferential grooves 21 and 24. More specifically, the outer narrow necks 72 of the resonator 70 located in the intermediate land portion 32 connect the air chamber 71 to the outer circumferential groove 21. Similarly, the outer narrow necks 72 of the resonator 70 located in the intermediate land portion 34 connect the air chamber 71 to the outer circumferential groove 24.

[0071] The resonator 70 does not have an inner narrow neck connecting the air chamber 71 to the inner circumferential grooves 22 and 23. That is, the resonator 70 provided in the intermediate land portion 32 does not include an inner narrow neck connecting the air chamber 71 to the inner circumferential groove 22. Similarly, the resonator 70 provided in the intermediate land portion 34 does not include an inner narrow neck connecting the air chamber 71 to the inner circumferential groove 23.

[0072] In this manner, the Helmholtz resonator 70 is disposed in the land portion (in this embodiment, intermediate land portions 32 and 34) defined between the outer circumferential grooves 21 and 24 and the inner circumferential grooves 22 and 23, which are adjacent to the outer circumferential grooves 21 and 24 and are formed by the meandering groove 20. The resonator 70 includes an outer narrow neck 72 connecting the air chamber 71 to the outer circumferential grooves 21 and 24, and does not have an inner narrow neck connecting the air chamber 70 to the inner circumferential grooves 22 and 23. This configuration allows the resonator 70 to reduce the sound pressure peak of the resonant sound of the air column in the outer circumferential grooves 21 and 24. Furthermore, since the resonator 70 does not have an inner narrow neck, the first groove wall 20a and the second groove wall 20b of the sinusoidal meandering groove 20 are not interrupted by the inner narrow neck. All other things being equal, the rigidity of the land portion with a meandering groove wall as its sidewall is less than the rigidity of the land portion with a straight groove wall along the tire circumferential direction C. Therefore, if the meandering first groove wall 20a and second groove wall 20b are interrupted in the tire circumferential direction C, the rigidity of the land portion with the first groove wall 20a as its sidewall and the rigidity of the land portion with the second groove wall 20b as its sidewall will be greatly reduced. Therefore, by constructing the first groove wall 20a and second groove wall 20b of the meandering groove 20 as in this embodiment so that they are not interrupted by the narrow inner neck, a significant reduction in the rigidity of the land portion where the resonator 70 is located can be prevented. As a result, a reduction in the braking performance of the tire 1 can be suppressed.

[0073] Both intermediate land sections 32 and 34 are provided with a plurality of resonators 70 spaced apart in the tire circumferential direction C. In each of the intermediate land sections 32 and 34, the distance between two adjacent resonators 70 in the tire circumferential direction C is set to be equal to or less than the ground contact length, which is the length of the tread contact surface in the tire circumferential direction C. The length of the air chamber 71 of the resonator 70 in the tire circumferential direction C is also set to be equal to or less than the ground contact length. (See tread surface view). Figure 2 In this embodiment, the air chamber 71 of the resonator 70 has a shape that is elongated along the tire circumference C, but its shape is not particularly limited. Similarly, each resonator 70 in this embodiment has only one outer narrow neck 72, but the number of outer narrow necks 72 is not particularly limited.

[0074] From another perspective, such as Figure 2 As shown, in this embodiment, the four circumferential grooves 21 to 24 have two inner circumferential grooves 22 and 23, which define a central landmass 33 intersecting the tire equatorial plane CL. The central landmass 33 does not have a resonator including an air chamber opening to the tread surface and a narrow neck connecting this air chamber to at least one of the two inner circumferential grooves 22 and 23. In other words, the central landmass 33 intersecting the tire equatorial plane CL does not have a Helmholtz resonator like the resonator 70 provided in the intermediate landmasses 32 and 34. This configuration prevents a reduction in the rigidity of the central landmass 33 located at the center of the tire width direction B on the tread surface T.

[0075] In particular, in this embodiment, the central land portion 33 is defined by two inner circumferential grooves 22 and 23 formed by the meandering groove 20. If the Helmholtz resonator is disposed in the central land portion 33, the narrow neck will connect to one of the two inner circumferential grooves 22 and 23. In this case, the rigidity of the central land portion 33 may be greatly reduced due to the breakage of the first groove wall 20a and the second groove wall 20b of the meandering groove 20, as described above. Therefore, as in this embodiment, if the central land portion 33 is defined by two inner circumferential grooves 22 and 23 formed by the meandering groove 20, it is preferable not to arrange the Helmholtz resonator in the central land portion 33.

[0076] Resonator 70, as a Helmholtz resonator, can be like... Figure 6 It is molded as shown, and its resonant frequency f0 can be expressed by the following equation (2), where l0 is the extension length of the outer narrow neck 72, S is the cross-sectional area, V is the volume of the air chamber 71, and c is the speed of sound.

[0077]

[0078] However, the length l0 of the outer narrow neck 72 should not be an actual measurement, but rather an opening end correction value that takes into account the additional vibration of the air inside the resonator 70 plus the air around the opening.

[0079] Therefore, the resonant frequency f0 of the resonator 70 can be varied as needed by selecting the cross-sectional area S of the outer narrow neck 72, the length l0 of the outer narrow neck 72, and the volume V of the air chamber 71, etc. If there are multiple outer narrow necks 72 connected to an air chamber 71, it is found that there is practically no problem in performing calculations by assuming that they are equivalent to a single outer narrow neck 72 having a cross-sectional area that is the sum of the cross-sectional areas of these multiple outer narrow necks 72 and using the average length of the multiple outer narrow necks 72 as the extension length.

[0080] As described above, a width direction groove 40 is formed in the shoulder land portions 31 and 35, which are defined by the outer circumferential grooves 21 and 24 and the tread end TE of the tread surface T, respectively. Furthermore, as described above, the width direction groove 40 in this embodiment opens toward the outer circumferential grooves 21 and 24, that is, it connects to the outer circumferential grooves 21 and 24.

[0081] In this embodiment, the width-direction groove 40 is formed at a position overlapping with the extension line of the outer narrow neck 72 of the resonator 70. In other words, assuming that the extension line of the outer narrow neck 72 of the resonator 70 extends from the side connected to the air chamber 71 to the opposite side of the resonator 70, the width-direction groove 40 of the shoulder land portions 31 and 35 extends in a manner overlapping with this extension line. This configuration achieves both drainage performance and aesthetic design.

[0082] In addition, such as Figure 2 As shown, the four circumferential grooves 21 to 24 include two inner circumferential grooves 22 and 23 formed by the meandering groove 20. The repetition period λ of one inner circumferential groove 22 formed by the meandering groove 20 on the tire circumferential C has a phase difference with the repetition period λ of the other inner circumferential groove 23 formed by the meandering groove 20 on the tire circumferential C. In other words, the repetition period λ of the inner circumferential groove 22 and the repetition period λ of the inner circumferential groove 23 are misaligned on the tire circumferential C. Similarly, the positions of the maximum width Wmax of the inner circumferential groove 22 and the minimum width Wmin of the inner circumferential groove 23 are different on the tire circumferential C. In this way, excessive changes in compressive stiffness on the tire circumferential C can be suppressed. This allows for noise suppression.

[0083] The tires included in this disclosure are not limited to the specific constructions described in the above embodiments, and can be modified, altered, and combined in various ways, as long as they do not depart from the scope of the claims. The tire 1 shown in the above embodiments includes four circumferential grooves 21 to 24 on the tread surface T, but it can be configured to have circumferential grooves composed of one or more meandering grooves 20. Therefore, the tire 1 can be configured to have five or more circumferential grooves. In this case, the five or more circumferential grooves consist of two outer circumferential grooves and three or more inner circumferential grooves. Only one of these three or more inner circumferential grooves may be composed of a meandering groove 20. Alternatively, multiple, but not all, of the three or more inner circumferential grooves may be composed of meandering grooves 20. Alternatively, all of the three or more inner circumferential grooves may be composed of meandering grooves 20. When multiple inner circumferential grooves are composed of meandering grooves 20, the repetition period λ of the multiple meandering grooves 20 preferably has a phase difference in the tire circumferential direction C in order to suppress changes in compressive stiffness in the tire circumferential direction C, as described above.

[0084] Furthermore, in the above embodiment, the two inner circumferential grooves 22 and 23 are formed by meandering grooves 20 of the same shape and size, having only a phase difference in the tire circumferential direction C. However, the two inner circumferential grooves 22 and 23 can be formed by meandering grooves 20 that differ from each other in at least one of their shapes and sizes. However, it is preferable that the grooves are formed by meandering grooves 20 of the same shape and size, such as the two inner circumferential grooves 22 and 23 in the above embodiment. In this way, by setting a phase difference in the tire circumferential direction C in the two inner circumferential grooves 22 and 23, changes in compressive stiffness in the tire circumferential direction C can be easily suppressed.

[0085] Furthermore, in the above embodiment, the two inner circumferential grooves 22 and 23, formed by the meandering groove 20, are formed on both sides of the tire width direction B, separated from the tire equator CL, at equal distances from each other. Specifically, for example, the distance from the center of the groove width in the tire width direction B to the tire equator CL at the position of the maximum width Wmax of the inner circumferential groove 22 and the distance from the center of the groove width in the tire width direction B to the tire equator CL at the position of the maximum width Wmax of the inner circumferential groove 23 should be equal. The same applies to the positions of the centers of the groove widths at the positions of the minimum width Wmin of the inner circumferential grooves 22 and 23. In this way, when multiple meandering grooves 20 exist, these multiple meandering grooves 20 are preferably located on both sides of the tire width direction B, separated from the tire equator CL, at equal distances from each other. In this way, it is possible to prevent the influence of axial force changes caused by the meandering groove 20 from one side to the other in the tire width direction B.

[0086] Industrial availability

[0087] This disclosure relates to tires.

[0088] Explanation of reference numerals in the attached figures

[0089] 1: Tire; 7: Tread rubber; 8: Sidewall rubber; 11: Bead portion; 11a: Bead core; 11b: Bead filler; 12: Sidewall portion; 13: Tire tread portion; 14: Tire body; 15: Belt; 16: Inner liner; 20: Winding groove; 20a: First groove wall; 20b: Second groove wall; 20c: Groove bottom; 21, 24: Outer circumferential groove (circumferential groove); 22, 23: Inner circumferential groove (circumferential groove, winding groove in the above embodiment); 31, 35: Shoulder land portion; 32, 34: Middle land portion; 33: Central land portion; 40: Width direction groove; 51a: Wide section; 51b: Narrow section; 70: Resonator; 71: Air chamber; 72: Outer narrow neck; 120, 220: Wandering groove of the comparative example; 120a, 220a: First groove wall of the wandering groove of the comparative example; 120b, 220b: Second groove wall of the wandering groove of the comparative example; A: Tire radial direction; B: Tire width direction; C: Tire circumferential direction; AP1: Amplitude of the first sinusoidal curve formed by the first groove wall; AP2: Amplitude of the second sinusoidal curve formed by the second groove wall; CL: Tire equatorial plane; D: Groove depth; L1 to L6: Sound wave; W: Groove width; λ: Repetition period.

Claims

1. A tire having a meandering groove formed on the tread surface extending circumferentially along the tire, wherein, The meandering groove has a groove width in the tire width direction, and the groove width varies along the tire circumference with a predetermined repeating period. When the maximum width of the slot is Wmax and the minimum width of the slot is Wmin, the ratio of the maximum width to the minimum width, Wmin / Wmax, is between 0.35 and 0.

85. The first and second groove walls, which are the two groove walls of the meandering groove, both extend in a sinusoidal meandering pattern with the predetermined repeating cycle as the length of one cycle in the tread surface view, and In the tread surface view, the first sinusoidal curve formed by the first groove wall and the second sinusoidal curve formed by the second groove wall are configured with a phase difference of 1 / 8 to 3 / 8 of the cycle in the tire circumferential direction. Three or more circumferential grooves extending along the tire circumference are formed on the tread surface. In the three or more circumferential grooves, the plurality of inner circumferential grooves located on the inner side in the tire width direction are formed by the meandering grooves, compared with the outermost outer circumferential grooves on both sides in the tire width direction. The plurality of inner circumferential grooves include two inner circumferential grooves, which define a central landmass intersecting the tire's equatorial plane. The maximum amplitude of the first sinusoidal curve formed by the first groove wall of one of the two inner circumferential grooves, the maximum amplitude of the second sinusoidal curve formed by the second groove wall of the one of the two inner circumferential grooves, the maximum amplitude of the first sinusoidal curve formed by the first groove wall of the other inner circumferential groove, and the maximum amplitude of the second sinusoidal curve formed by the second groove wall of the other inner circumferential groove are equal in the tread surface view.

2. The tire according to claim 1, wherein, The repetition period of the first and second sinusoidal curves in the tread surface view is 15 to 100 times the maximum amplitude of the first and second sinusoidal curves in the tire width direction.

3. The tire according to claim 1, wherein, In the tread surface view, the outer circumferential groove extends in a straight line along the tire circumference.

4. The tire according to claim 1, wherein, One of the two inner circumferential grooves is adjacent to one of the outer circumferential grooves. A resonator is provided in the land portion defined between one of the outer circumferential grooves and one of the two inner circumferential grooves. The resonator includes: Air chamber, which opens to the tread surface of the land portion; and One or more lateral narrow necks that connect the air chamber to the one lateral circumferential groove, and The resonator does not have an inner narrow neck that connects the air chamber to the inner circumferential groove of one of the two inner circumferential grooves.

5. The tire according to claim 3, wherein, One of the two inner circumferential grooves is adjacent to one of the outer circumferential grooves. A resonator is provided in the land portion defined between one of the outer circumferential grooves and one of the two inner circumferential grooves. The resonator includes: Air chamber, which opens to the tread surface of the land portion; and One or more lateral narrow necks that connect the air chamber to the one lateral circumferential groove, and The resonator does not have an inner narrow neck that connects the air chamber to the inner circumferential groove of one of the two inner circumferential grooves.

6. The tire according to claim 4, wherein, A width direction groove is formed at a position in the shoulder land defined between the outer circumferential groove and the tread end of the tread surface, at a position that overlaps with the extension line of the outer narrow neck provided on the land, the width direction groove opening toward the outer circumferential groove.

7. The tire according to claim 5, wherein, A width direction groove is formed at a position in the shoulder land defined between the outer circumferential groove and the tread end of the tread surface, at a position that overlaps with the extension line of the outer narrow neck provided on the land, the width direction groove opening toward the outer circumferential groove.

8. The tire according to any one of claims 4 to 7, wherein, The central land section does not have a resonator comprising an air chamber opening to the tread surface and a narrow neck connecting the air chamber to at least one of the two inner circumferential grooves.

9. The tire according to any one of claims 1, 3 to 7, wherein, The repetition period of one of the two inner circumferential grooves in the tire circumferential direction has a phase difference with the repetition period of the other inner circumferential groove in the tire circumferential direction.

10. The tire according to claim 8, wherein, The repetition period of one of the two inner circumferential grooves in the tire circumferential direction has a phase difference with the repetition period of the other inner circumferential groove in the tire circumferential direction.

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