tire

Abstract

Control the rigidity of the land area where sipes are formed. [Solution] The tire 10 has a plurality of circumferential grooves 11, 12, 13 provided in the tread portion 15, shoulder land portions 21, 22 provided in the tread portion 15 and located at the ends in the tire width direction, a plurality of central land portions 31, 32 provided in the tread portion 15 and partitioned by the circumferential grooves 11, 12, 13 and located between the shoulder land portions on both sides, a plurality of lateral grooves 23 provided in the shoulder land portions and extending in the tire width direction, shoulder sipes 21A, 22A provided between the plurality of lateral grooves 23 in the shoulder land portions, and central sipes 31A, 32A that cross the central land portions, and a bent portion 25, 35 is provided in a part of the length direction of the shoulder sipes and central sipes that has an amplitude in the width direction of each sipe in the depth direction of each sipe, and the other parts of the shoulder sipes and central sipes are general portions 26, 36 that do not have the bent portions 25, 35.

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] There is disclosed a tire in which a sipe formed in a land portion of a tread surface has at least one bent portion continuously extending in the extending direction of the sipe from one end region of the sipe to the other end region in the depth direction of the sipe, and the bent portion is located radially outside the tire in the central region of the sipe than in the end region (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, there is still room for improvement in order to improve various performances of the tire.

[0005] An object of the present invention is to control the rigidity of a land portion in which a sipe is formed.

Means for Solving the Problems

[0006] A tire according to the first embodiment has a plurality of circumferential grooves provided on the tread portion and extending in the circumferential direction of the tire, a shoulder land portion provided on 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 on 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 that crosses 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.

[0007] In this tire, the lateral grooves and shoulder sipes on the shoulder treads enhance drainage at the contact surface, thereby improving wet performance. Furthermore, a portion of the length of the shoulder sipes and central sipes is provided with a bent section that has amplitude in the width direction of each sipe in the depth direction of each sipe, while the other parts of the shoulder sipes and central sipes are general sections without bent sections. This suppresses the relative deformation between the shoulder treads surrounding the shoulder sipes and between the central treads surrounding the central sipes, i.e., the shear deformation of the shoulder treads and central treads, thereby controlling the rigidity of the shoulder treads and central treads. As a result, wet performance can be improved without reducing braking performance or wear resistance.

[0008] The second embodiment is a tire according to the first embodiment, wherein the tire has a central second sipe that traverses the central land portion and extends in a direction intersecting the central first sipe, and does not have a bent portion.

[0009] In this tire, the shoulder sipes terminate within the shoulder area, and the shoulder area is not completely separated by the shoulder sipes. Therefore, it has higher rigidity than the central area traversed by the central sipes. Consequently, the rigidity of the shoulder area can be ensured even if the extended length of the bend in the longitudinal direction of the shoulder sipes is smaller than the extended length of the bend in the longitudinal direction of the central sipes.

[0010] 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 equator, respectively. [Effects of the Invention]

[0011] According to the present invention, the rigidity of the land area on which the sipes are formed can be controlled. [Brief explanation of the drawing]

[0012] [Figure 1] This is a plan view showing the tread portion of the tire according to this embodiment, unfolded in the circumferential direction of the tire. [Figure 2] (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. [Figure 3] (A) is a cross-sectional view taken along the line 3A-3A in Figure 1, showing the first shoulder sipe. (B) is a cross-sectional view taken along the line 3B-3B in Figure 1, showing the first shoulder sipe. [Figure 4] This is a plan view showing the tread portion of a modified tire, unfolded in the circumferential direction. [Modes for carrying out the invention]

[0013] The embodiments for carrying out the present invention will be described below with reference to the drawings. Components indicated by the same reference numerals in each drawing are 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 axis of rotation. 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 area 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 area is the outer shoulder area 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 area is the inner shoulder area 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] The outer shoulder land portion 21 and the inner shoulder land portion 22 are each provided with a plurality of transverse grooves 23 extending in the tire width direction. The transverse grooves 23 extend from the inner side to the outer side in the tire width direction of the grounding end T of the tread portion 15. The inner end portion of the transverse groove 23 in the tire width direction becomes a fine groove 24 and opens into the circumferential grooves 11 and 13 respectively.

[0020] The outer center land portion 31 and the inner center land portion 32 are provided in the tread portion 15, partitioned by the circumferential grooves 11, 12, and 13, and 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 in a rib shape in the tire circumferential direction, for example. The outer center land portion 31 is partitioned by the circumferential grooves 11 and 12 and is located on the outer side of the vehicle mounting side between the outer shoulder land portion 21 and the inner shoulder land portion 22. The inner center land portion 32 is partitioned by the circumferential grooves 12 and 13 and is located on the inner side of the vehicle mounting side between the outer shoulder land portion 21 and the inner shoulder land portion 22.

[0021] The outer center land portion 31 and the inner center land portion 32 are provided with first center sipes 31A and 32A as an example of a center sipe that crosses the land portion. A bent portion 35 having an amplitude in the width direction of the first center sipes 31A and 32A in the depth direction is provided in a part of the length direction of the first center sipes 31A and 32A, for example, at the center. As shown in FIG. 2, the cross-sectional shape of the bent portion 35 is, for example, zigzag, and its amplitude is the largest at the center of the bent portion 35 in the length direction of each sipe and becomes smaller at the end portions of the bent portion 35.

[0022] Other parts in the length direction of the first center sipes 31A and 32A, for example, both end portions, are general portions 36 without the bent portion 35.

[0023] The outer center land portion 31 is provided with a second center sipe 31B that extends in a direction intersecting the first center sipes 31A and 32A and does not have the bent portion 35. This second center sipe 31B is not provided in the inner center 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, and the difference L2 between the circumferential positions of the ends of the ends that are far apart 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 block edges decreases, and the edge portion with low block rigidity makes continuous contact with the road surface, increasing the input of the variable component due to block deformation and increasing pitch noise. Also, if the difference L1 and L2 is greater than 1.16, the input of the variable 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 shoulder sipe 1, 21A, is provided between the multiple transverse grooves 23, as an example of a shoulder sipe. In the inner shoulder land area 22, a shoulder sipe 1, 22A, and a shoulder sipe 22B are provided between the multiple transverse grooves 23, as examples of shoulder sipes.

[0026] A portion of the central first sipe 31A, 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 sipe 31A, 32A in the depth direction of the central first sipe 31A, 32A. Other portions of the central first sipe 31A, 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. 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. 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] (action) This embodiment is configured as described above, and its operation 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 flanking 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 positioning 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 area (outer shoulder land area 21, inner shoulder land area 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 sections 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 sections 26, 36 that do not have bent sections 25, 35. This suppresses the relative deformation between the shoulder land sections flanking the shoulder sipes and between the central land sections flanking the central sipes, i.e., the shear deformation of the shoulder land sections and central land sections, thereby controlling the rigidity of the shoulder land sections and central land sections. 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 sipes on the shoulder land portion enhance drainage of the contact surface, thereby improving wet performance. Additionally, a first bend 25 is provided on a portion of the first shoulder sipe on 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 parts 26 without the first bend 25. This suppresses relative deformation between the shoulder land portions flanking 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 shoulder second sipe 22B which does not have a bent portion 25, the number of shoulder second sipes 22B on the inner shoulder land portion 22 is greater than the number of shoulder second sipes 22B on the outer shoulder land portion 21, so the rigidity of the outer shoulder land portion 21 is higher than the rigidity of the inner shoulder land portion 22. Therefore, the rigidity of the outer shoulder land portion 21, which is subjected to a larger load during turning, can be increased to improve turning performance. In addition, because the number of shoulder second sipes 22B on the inner shoulder land portion 22 is greater than the number of shoulder second sipes 22B on the outer shoulder land portion 21, the drainage performance of the inner shoulder land portion 22 is high. Furthermore, because the rigidity of the inner shoulder land portion 22 is lower than the rigidity of the outer shoulder land portion 21, NV performance and ride comfort during straight-line driving can be improved, especially when negative camber is set.

[0045] Furthermore, since the number of central second sipes 31B in the outer central land portion 31 is greater than the number of central second sipes 31B in the inner central land portion 32, NVH (noise, vibration, and harshness) is reduced in the central region of the tread portion 15. In addition, since the rigidity of the inner central land portion 32 is higher than that of the outer central land portion 31, the decrease in rigidity of the inner shoulder land portion 22 is compensated for, and steering stability performance can be ensured.

[0046] Furthermore, since the rigidity of the land portion is 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, the rigidity balance of the entire tread portion 15 can be optimized, improving NVH performance, handling stability, and wet performance. Thus, according to this embodiment, the rigidity balance of the entire tread portion 15 can be optimized.

[0047] (modified version) In Figure 4, the modified tire 10 has circumferential grooves 14 added compared to the example in Figure 1. Also, as an example of a central land section, an intermediate central land section 33 is provided between the outer central land section 31 and the inner central land section 32. In other words, this tire 10 has four circumferential grooves and three rows of rib-shaped land sections as the central land section. The intermediate central land section 33 is located, for example, at the position of the tire's equatorial plane CL. A central first sipe 33A is formed in the intermediate central land section 33, which is configured in the same way as the inner central land section 32.

[0048] [Other embodiments] Although an example of an embodiment of the present invention has been described above, the embodiments of the present invention are not limited to those described above, and it goes without saying that various modifications can be made and implemented without departing from the spirit of the invention. [Explanation of Symbols]

[0049] 10...Tire, 11...Circumferential groove, 12...Circumferential groove, 13...Circumferential groove, 14...Circumferential groove, 15...Tread section, 21...Outer shoulder section (shoulder section), 21A...Shoulder 1st sipe, 22...Inner shoulder section (shoulder section), 22A...Shoulder 1st sipe, 22B...Shoulder 2nd sipe, 22B1...Deep position, 22C...Pinhole groove, 23...Lateral groove, 24... Narrow groove, 25...bent section, 26...general section, 31...outer central land section (central land section), 31A...central 1st sipe, 31B...central 2nd sipe, 32...inner central land section (central land section), 32A...central 1st sipe, 33...intermediate central land section (central land section), 33A...central 1st sipe, 35...bent section, 36...general section, T...contact edge, L1...difference in tire circumferential position, L2...difference in tire circumferential position

Claims

1. Multiple circumferential grooves are provided in the tread portion and extend in the circumferential direction of the tire, The tread portion is provided, is partitioned by the circumferential groove, and has a shoulder portion located at the end in the tire width direction, The tread portion is provided, is partitioned by the circumferential groove, and comprises a plurality of central land portions located between the shoulder land portions on both sides, Multiple lateral grooves extending in the tire width direction are provided on the shoulder land portion, A shoulder sipe is provided between the plurality of transverse grooves in the aforementioned shoulder land portion, It has a central sipe that crosses the central land area, A portion of the shoulder sipe and the central sipe is provided with a bent portion in the longitudinal direction, having an amplitude in the width direction of each sipe in the depth direction of each sipe. A tire in which the shoulder sipe and the other parts of the central sipe are general parts that do not have the bent portion.

2. The aforementioned shoulder sipe terminates within the shoulder land portion, The tire according to claim 1, wherein the extended length of the bent portion in the longitudinal direction of the shoulder sipe is smaller than the extended length of the bent portion in the longitudinal direction of the central sipe.

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