Tire

Abstract

A tire 10 comprises: a plurality of circumferential grooves 11, 12, 13 provided in a tread portion 15 and extending in a tire circumferential direction; shoulder land portions provided in the tread portion 15, partitioned by the circumferential grooves 11, 12, 13, and located at end portions in a tire width direction; a plurality of rib-like central land portions provided in the tread portion 15, partitioned by the circumferential grooves 11, 12, 13, located between the shoulder land portions on both sides, and extending in the tire circumferential direction; and central first sipes 31A, 32A crossing the central land portions. A bent portion 35 having an amplitude in a width direction of the central first sipes 31A, 32A in a depth direction of the central first sipes 31A, 32A is provided at a central portion in a length direction of the central first sipes 31A, 32A. Both end portions in the length direction of the central first sipes 31A, 32A are general portions 36 not having the bent portion 35.

Description

Tire 【0001】 This disclosure relates to a tire. 【0002】 Japanese Unexamined Patent Application Publication No. 2023-146910 discloses a tire in which a plurality of rib-shaped land portions extending in the tire circumferential direction are provided in the tread portion, and sipe inclined with respect to the tire width direction is formed in the land portion. In this tire, by making the tire circumferential positions of the closer ends of the sip adjacent to each other in the tire width direction coincide with each other and the tire circumferential positions of the farther ends of the sip adjacent to each other coincide with each other over the entire tire circumferential direction, the running noise is reduced. 【0003】 However, when forming a sipe as in the above-described conventional example, it is considered that the rib-shaped land portion is likely to shear-deform when the tread portion contacts the ground. 【0004】 An object of this disclosure is to control the rigidity of a rib-shaped land portion in which a sipe is formed. 【0005】 The tire according to the first tire includes a plurality of circumferential grooves provided in the tread portion and extending in the tire circumferential direction, a shoulder land portion provided in the tread portion, partitioned by the circumferential grooves, and located at the tire width direction end portion, and a plurality of rib-shaped central land portions provided in the tread portion, partitioned by the circumferential grooves, located between the shoulder land portions on both sides, and extending in the tire circumferential direction, and a central first sipe crossing the central land portion. A bent portion having an amplitude in the width direction of the central first sipe in the depth direction is provided at the central portion in the length direction of the central first sipe, and both end portions in the length direction of the central first sipe are general portions having no bent portion. 【0006】 In this tire, a bent portion in the depth direction of the central first sipe is provided at the central portion in the length direction of the central first sipe crossing the rib-shaped central land portion, and both end portions in the length direction of the central first sipe are general portions having no bent portion. Therefore, the relative deformation between the land portions sandwiching the central first sipe, that is, the shear deformation of the central land portion can be suppressed, and the rigidity of the central land portion can be controlled. 【0007】The second embodiment is an embodiment relating to the first embodiment, wherein the second central sipe extends in a direction that crosses the central land portion and intersects with the first central sipe, and has no bent portion. 【0008】 This tire ensures wet performance by incorporating a central second sipe that does not have a bent section. 【0009】 The third embodiment is a tire according to the first or second embodiment, in which the difference in the circumferential position of the ends of adjacent central first sipes in the tire width direction that are close to each other in the tire width direction, and the difference in the circumferential position of the ends that are far from each other, is 0.28 to 1.16% of the circumferential length of the tread surface at the tire equatorial plane, respectively. 【0010】 In this tire, by setting the position of the end of the central first sipe within the above range and appropriately positioning the central first sipe, shear deformation of the rib-shaped central land portion can be suppressed more effectively. 【0011】 According to this disclosure, the rigidity of the rib-shaped land portion on which the sipes are formed can be controlled. 【0012】 This is a plan view showing the tread portion of the tire according to this embodiment, unfolded in the circumferential direction of the tire. (A) is a cross-sectional view taken along the line 2A-2A in Figure 1, showing the central first sipe. (B) is a cross-sectional view taken along the line 2B-2B in Figure 1, showing the central first sipe. (A) is a cross-sectional view taken along the line 3A-3A in Figure 1, showing the shoulder first sipe. (B) is a cross-sectional view taken along the line 3B-3B in Figure 1, showing the shoulder first sipe. This is a plan view showing the tread portion of a modified tire, unfolded in the circumferential direction of the tire. 【0013】The embodiments for implementing this disclosure will be described below with reference to the drawings. Components indicated by the same reference numerals in each drawing are considered to be the same or similar components. In the embodiments described below, descriptions and reference numerals that are repeated may be omitted. Furthermore, the drawings used in the following description are all schematic, and the dimensional relationships and ratios of each element shown in the drawings do not necessarily correspond to reality. Also, the dimensional relationships and ratios of each element do not necessarily correspond between multiple drawings. 【0014】 In the drawing, arrow C indicates the circumferential direction of the tire, and arrow W indicates the width direction of the tire. The width direction of the tire means the direction parallel to the tire's rotation axis. The width direction of the tire can also be described as the axial direction of the tire. In the drawing, "OUT" indicates the outside of the vehicle mounting, and "IN" indicates the inside of the vehicle mounting. 【0015】 The method for measuring the dimensions of each part shall be in accordance with the method described in the 2024 YEAR BOOK published by JATMA (Japan Automobile Tire Manufacturers Association). If TRA standards or ETRTO standards apply in the place of use or manufacture, the respective standards shall be followed. 【0016】 In Figure 1, the tire 10 according to this embodiment has a plurality (for example, three) of circumferential grooves 11, 12, 13, an outer shoulder land portion 21 and an inner shoulder land portion 22 as an example of a shoulder land portion, and an outer central land portion 31 and an inner central land portion 32 as an example of a central land portion. 【0017】 The circumferential grooves 11, 12, and 13 are main grooves provided in the tread portion 15 and extending in the circumferential direction of the tire. In the illustrated example, the circumferential groove 12 is located on the tire equatorial plane CL. The circumferential grooves 11 and 13 are located on the outer side of the circumferential groove 12 in the tire width direction, specifically on the outer side and inner side of the vehicle mounting, respectively. 【0018】The shoulder land portion is provided on the tread portion 15, is demarcated by circumferential grooves 11, 12, and 13, and is located at the end in the tire width direction. An example of a shoulder land portion is the outer shoulder land portion 21, which is located further outward from the circumferential groove 11 that is located on the outermost side of the vehicle, i.e., at the outer end of the vehicle mounting. An example of a shoulder land portion is the inner shoulder land portion 22, which is located further inward from the circumferential groove 13 that is located on the innermost side of the vehicle mounting, i.e., at the inner end of the vehicle mounting. 【0019】 Multiple lateral grooves 23 extending in the tire width direction are provided on the outer shoulder land portion 21 and the inner shoulder land portion 22, respectively. The lateral grooves 23 extend from the inner side to the outer side in the tire width direction of the contact end T of the tread portion 15. The inner end of the lateral groove 23 in the tire width direction becomes a narrow groove 24 and opens into the circumferential grooves 11 and 13, respectively. 【0020】 The outer central land portion 31 and the inner central land portion 32 are provided on the tread portion 15, are demarcated by circumferential grooves 11, 12, and 13, are located between the shoulder land portions on both sides, specifically the outer shoulder land portion 21 and the inner shoulder land portion 22, and extend, for example, in a rib-like manner in the circumferential direction of the tire. The outer central land portion 31 is demarcated by circumferential grooves 11 and 12 and is located on the vehicle mounting side between the outer shoulder land portion 21 and the inner shoulder land portion 22. The inner central land portion 32 is demarcated by circumferential grooves 12 and 13 and is located on the vehicle mounting side between the outer shoulder land portion 21 and the inner shoulder land portion 22. 【0021】 The outer central land portion 31 and the inner central land portion 32 are provided with central first sipes 31A and 32A, which are examples of central sipes that traverse the land portion. A portion of the central first sipes 31A and 32A in the longitudinal direction, for example in the central portion, is provided with a bent portion 35 that has an amplitude in the width direction of the central first sipes 31A and 32A in the depth direction of the central first sipes 31A and 32A. The cross-sectional shape of the bent portion 35 is, for example, zigzag, as shown in Figure 2, and its amplitude is largest in the center of the bent portion 35 in the longitudinal direction of each sipe and decreases at the ends of the bent portion 35. 【0022】Other parts of the central first sipes 31A and 32A in the longitudinal direction, such as both ends, are general sections 36 that do not have bent sections 35. 【0023】 The outer central land portion 31 is provided with a central second sipe 31B that extends in a direction intersecting the central first sipes 31A and 32A and does not have a bent portion 35. This central second sipe 31B is not provided on the inner central land portion 32. 【0024】 The difference L1 between the circumferential positions of the ends of adjacent central first sipes 31A and 32A in the tire width direction that are closer to each other in the tire width direction, and the difference L2 between the circumferential positions of the ends that are farther from each other, are, for example, 0.28 to 1.16% of the circumferential length of the tread surface at the tire equatorial plane CL. Here, if the difference L1 and L2 is less than 0.28, the difference between the block edges decreases, and the edge portion with low block rigidity makes continuous contact with the road surface, so the input of the fluctuating component due to block deformation increases and pitch noise increases. Also, if the difference L1 and L2 is greater than 1.16, the input of the fluctuating component due to the discontinuous contact of the block edge ends with the road surface increases and pitch noise increases. 【0025】 In the outer shoulder land area 21, a first shoulder sipe 21A, as an example of a shoulder sipe, is provided between the multiple transverse grooves 23. In the inner shoulder land area 22, a first shoulder sipe 22A and a second shoulder sipe 22B, as examples of shoulder sipes, are provided between the multiple transverse grooves 23. 【0026】 A portion of the central first sipes 31A and 32A in the longitudinal direction, for example, the central portion, is provided with a bent portion 35 that has an amplitude in the width direction of the central first sipes 31A and 32A in the depth direction of the central first sipes 31A and 32A. Other portions of the central first sipes 31A and 32A in the longitudinal direction, for example, both ends, are general portions 36 that do not have the bent portion 35. 【0027】A portion of the shoulder first sipes 21A and 22A in the longitudinal direction is provided with a bent portion 25 having an amplitude in the width direction of the shoulder first sipes 21A and 22A in the depth direction of the shoulder first sipes 21A and 22A, respectively. The cross-sectional shape of the bent portion 25 is, for example, zigzag, as shown in Figure 3, and its amplitude is largest in the center of the bent portion 25 in the longitudinal direction of each sipe and decreases at the end of the bent portion 25. The other portions of the shoulder first sipes 21A and 22A in the longitudinal direction are general portions 26 that do not have bent portions 25. 【0028】 In the inner shoulder land portion 22, a second shoulder sipe 22B may be provided between the first shoulder sipe 21A and a lateral groove 23 adjacent to one side of the first shoulder sipe 21A in the tire circumferential direction. The second sipe 22B may intersect with the first shoulder sipe 21A. In addition, a pinhole groove 22C, as an example of a shoulder sipe, may be provided between the first shoulder sipe 22A and a lateral groove 23 adjacent to the other side of the first shoulder sipe 22A in the tire circumferential direction. 【0029】 These shoulder sipes terminate within the outer shoulder land portion 21 and the inner shoulder land portion 22, respectively. The extended length L21 of the bent portion 25 in the longitudinal direction of the first shoulder sipe 21A may be smaller than the extended length L31 of the bent portion 35 in the longitudinal direction of the central first sipe 31A. Furthermore, the depth of the second shoulder sipe 22B may be partially deepened at a position 22B1 where the second shoulder sipe 22B overlaps with the pinhole groove 22C in the circumferential direction of the tire. 【0030】 The number of shoulder second sipes 22B in the inner shoulder land area 22 may be greater than the number of shoulder second sipes in the outer shoulder land area 21. In the illustrated example, there are no shoulder second sipes in the outer shoulder land area 21, and the number of shoulder second sipes 22B in the inner shoulder land area 22 is greater than the number of shoulder second sipes in the outer shoulder land area 21. 【0031】The number of central second sipes 31B in the outer central land area 31 may be greater than the number of central second sipes in the inner central land area 32. In the illustrated example, there are no central second sipes in the inner central land area 32, and the number of central second sipes 31B in the outer central land area 31 is greater than the number of central second sipes in the inner central land area 32. 【0032】 The rigidity of the land portion may be highest in the order of outer shoulder land portion 21, inner shoulder land portion 22, inner central land portion 32, and outer central land portion 31. 【0033】 (Function) This embodiment is configured as described above, and its function will be explained below. In Figures 1 to 3, in the tire 10 according to this embodiment, a bent portion 35 in the depth direction of the central first sipes 31A and 32A is provided at the center of the length direction of the central first sipes 31A and 32A that cross the rib-shaped central land portion (outer central land portion 31, inner central land portion 32), and both ends of the central first sipes 31A and 32A in the length direction are general portions 36 that do not have the bent portion 35. Therefore, the relative deformation between the land portions sandwiching the central first sipes 31A and 32A, that is, the shear deformation of the central land portion, can be suppressed and the rigidity of the central land portion can be controlled. 【0034】 Furthermore, by providing a central second sipe 31B without a bent portion 35 on the outer central land portion 31, wet performance can be ensured. 【0035】 Furthermore, by setting the difference L1 and L2 at the ends of the central first sipes 31A and 32A within the above range and appropriately arranging the central first sipes 31A and 32A, shear deformation of the rib-shaped central land portion can be suppressed more effectively. 【0036】 According to this embodiment, the rigidity of the rib-shaped land portion on which the sipes are formed can be controlled. 【0037】Furthermore, the lateral grooves 23 of the shoulder land portion (outer shoulder land portion 21, inner shoulder land portion 22) and the shoulder sipes (shoulder first sipes 21A, 22A, shoulder second sipe 22B, pinhole grooves 22C) can improve drainage of the contact surface, thereby improving wet performance. Furthermore, the shoulder sipes (shoulder first sipes 21A, 22A and central first sipes 31A, 32A) are provided with bent portions 25, 35 in the longitudinal direction, which have an amplitude in the width direction of each sipe in the depth direction of each sipe. The other parts of the shoulder sipes and central sipes (central first sipes 31A, 32A) are general portions 26, 36 that do not have bent portions 25, 35. This suppresses the relative deformation between the shoulder land portions that sandwich the shoulder sipes and between the central land portions that sandwich the central sipes, i.e., the shear deformation of the shoulder land portions and central land portions, thereby controlling the rigidity of the shoulder land portions and central land portions. As a result, wet performance can be improved without reducing braking performance and wear resistance. 【0038】 Furthermore, since the shoulder sipe terminates within the shoulder land area and the shoulder land area is not completely divided by the shoulder sipe, it has higher rigidity than the central land area traversed by the central sipe. Therefore, even if the extended length L21 of the bent portion 25 in the longitudinal direction of the shoulder sipe is made smaller than the extended length L31 of the bent portion 35 in the longitudinal direction of the central sipe, the rigidity of the shoulder land area can be ensured. 【0039】 Therefore, the rigidity of the land area where the sipes are formed can be controlled. 【0040】Furthermore, the lateral grooves 23 and the first shoulder sipe of the shoulder land portion enhance drainage of the contact surface, thereby improving wet performance. Additionally, a bent portion 25 is provided on a part of the first shoulder sipe of the shoulder land portion, having an amplitude in the width direction of the first shoulder sipe in the depth direction of the first shoulder sipe, while the other parts of the first shoulder sipe are general portions 26 without the bent portion 25. This suppresses relative deformation between the shoulder land portions that sandwich the first shoulder sipe, i.e., shear deformation of the shoulder land portion, thereby controlling the rigidity of the shoulder land portion. As a result, wet performance can be improved without reducing braking performance and wear resistance. 【0041】 When negative camber is applied to the wheels during vehicle alignment, the ground pressure on the inner shoulder portion of the tire increases. During tire rotation, a large force is applied to the contact surface of the shoulder portion, affecting noise and ride comfort. In this tire, a pinhole groove 22C is provided on the shoulder portion, which reduces the compressive rigidity of the shoulder portion and mitigates road surface input. This reduces NVH (noise, vibration, and harshness). Furthermore, a second shoulder sipe 22B is provided on the shoulder portion, allowing shear force input to be released by deformation of the shoulder portion. 【0042】 Furthermore, since the depth of the shoulder second sipe 22B is partially deepened at the position 22B1 where the shoulder second sipe 22B overlaps with the pinhole groove 22C in the circumferential direction of the tire, the difference in rigidity in the circumferential direction of the tire at the location where the pinhole groove 22C is located can be mitigated. 【0043】 Therefore, the rigidity of the land area inside the tire mounting area can be controlled. 【0044】Regarding the second shoulder type 22B without the bent portion 25, the number of the second shoulder types 22B in the inner shoulder land portion 22 is larger than the number of the second shoulder types 22B in the outer shoulder land portion 21. Therefore, the rigidity of the outer shoulder land portion 21 is higher than the rigidity of the inner shoulder land portion 22. Thus, it is possible to increase the rigidity of the outer shoulder land portion 21 where a larger load acts during turning to improve the turning performance. Also, since the number of the second shoulder types 22B in the inner shoulder land portion 22 is larger than the number of the second shoulder types 22B in the outer shoulder land portion 21, the drainage property of the inner shoulder land portion 22 is high. Furthermore, since the rigidity of the inner shoulder land portion 22 is lower than the rigidity of the outer shoulder land portion 21, it is possible to improve the NV performance and the riding comfort during straight running especially when a negative camber is set. 【0045】 Also, the number of the central second types 31B in the outer central land portion 31 is larger than the number of the central second types 31B in the inner central land portion 32. Therefore, the NV in the central region of the tread portion 15 is reduced. Also, since the rigidity of the inner central land portion 32 becomes higher than that of the outer central land portion 31, the reduction in the rigidity of the inner shoulder land portion 22 can be compensated to ensure the handling stability performance. 【0046】 Furthermore, since the land portion rigidity is in the order of the outer shoulder land portion 21, the inner shoulder land portion 22, the inner central land portion 32, and the outer central land portion 31 from low to high, the rigidity balance of the entire tread portion 15 can be optimized to improve the NV performance, the handling stability performance, and the wet performance. Thus, according to this embodiment, the rigidity balance of the entire tread portion 15 can be optimized. That is, an improved tire can be provided. 【0047】 (Modification) In FIG. 4, in the tire 10 according to the modification, circumferential grooves 14 are added to the example of FIG. 1. Also, as an example of the central land portion, an intermediate central land portion 33 is provided between the outer central land portion 31 and the inner central land portion 32. That is, this tire 10 has four circumferential grooves and three rows of rib-shaped land portions as the central land portion. The intermediate central land portion 33 is, for example, at the position of the tire equatorial plane CL. The central first type 33A having the same configuration as the inner central land portion 32 is formed in the intermediate central land portion 33. 【0048】 [Other Embodiments] Although an example of an embodiment of the present disclosure has been described above, the embodiments of the present disclosure are not limited to the above, and it is needless to say that various modifications can be made without departing from the gist thereof. 【0049】 The disclosure of Japanese Patent Application No. 2024-219016 filed on December 13, 2024 is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference.

Claims

1. A tire having: a plurality of circumferential grooves provided in the tread portion and extending in the circumferential direction of the tire; a shoulder land portion provided in the tread portion, partitioned by the circumferential grooves and located at the end in the width direction of the tire; a plurality of rib-shaped central land portions provided in the tread portion, partitioned by the circumferential grooves and located between the shoulder land portions on both sides and extending in the circumferential direction of the tire; and a central first sipe traversing the central land portion, wherein a bent portion is provided in the central part of the central first sipe in the longitudinal direction, having an amplitude in the width direction of the central first sipe in the depth direction of the central first sipe, and both ends of the central first sipe in the longitudinal direction are general portions without the bent portion.

2. The tire according to claim 1, having a central second sipe that traverses the central land portion and extends in a direction intersecting the central first sipe, and which does not have a bent portion.

3. The tire according to claim 1 or claim 2, wherein the difference in the circumferential position of the ends of adjacent central first sipes in the tire width direction that are close to each other in the tire width direction, and the difference in the circumferential position of the ends that are far from each other, is 0.28 to 1.16% of the circumferential length of the tread surface at the tire equatorial plane.

Images