tire

Abstract

To provide a tire enhancing appearance by the surface shape of a buttress part.SOLUTION: In an objective tire, a flexure recess part 42 extending in a tire circumferential direction CD while displacing toward outside in a tire radial direction RD is provided on the surface of a buttress part 30 between a ground contact end TE of a tread and a sidewall 38. The flexure recess part 42 extends while vaulting so that the angle of the end part 42A of the ground contact end TE among both end parts in the tire circumferential direction CD to that direction CD becomes smaller than that of the end part 42B at a sidewall 38 side.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE An embodiment of the present invention relates to a tire. [Background technology]

[0002] In a tire, the region between the ground-contact edge of the tread and the sidewall is called a buttress portion. Patent Document 1 discloses a tire with a recess on the surface of the buttress portion, in which multiple curved convex portions are provided extending from the ground-contact edge toward the inside in the tire radial direction, and curved concave portions are formed between the curved convex portions. The curved concave portions in Patent Document 1 are provided to improve on-snow performance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-182067 A Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for improved appearance in tires, and improving the design of the buttress portion is considered to be an effective way to achieve this.

[0005] In view of the above, an object of an embodiment of the present invention is to provide a tire that can improve appearance by integrating the surface shape of the buttress portion. [Means for solving the problem]

[0006] A tire according to an embodiment of the present invention has a curved recess on the surface of the buttress portion between the ground-contact end of the tread and the sidewall, the curved recess extending circumferentially of the tire while being displaced radially outward, and the curved recess extends in a curved manner such that of both circumferential ends of the tire, the end on the ground-contact end side forms a smaller angle with respect to the tire circumferential direction than the end on the sidewall side. Effect of the Invention

[0007] According to this embodiment, the curved recessed portion imparts a curved design to the buttress portion, improving the design of the buttress portion and improving the external appearance of the tire. Furthermore, the provision of the curved recessed portion improves external damage resistance. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a development view showing a tread pattern of a tire according to an embodiment. [Diagram 2] FIG. 3 is a cross-sectional view showing the outer shape of the tread of the tire. [Diagram 3] FIG. 4 is a perspective view of a main part of the tire showing a buttress portion. [Figure 4] FIG. 1 is a side view showing a main part of the buttress portion of the tire. [Diagram 5] Cross-sectional view of line VV in Figure 4 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment will be described with reference to the drawings.

[0010] The tire according to one embodiment is a pneumatic tire for passenger cars, and is configured to include a pair of left and right beads and sidewalls, and a tread provided between both sidewalls so as to connect the radially outer ends of the left and right sidewalls to each other. The internal structure of the tire is not particularly limited, and may include, for example, an annular bead core embedded in the bead, a carcass ply having a radial structure extending in a toroidal shape between the pair of beads, and a belt and tread rubber provided on the radially outer side of the carcass ply in the tread. In this embodiment, the internal structure of the tire is not particularly limited, and a general tire structure may be adopted.

[0011] In this specification, unless otherwise specified, the shapes and dimensions are those of a tire mounted on a standard rim and inflated to the standard internal pressure under normal load. A standard rim is a "standard rim" in the JATMA standard, a "design rim" in the TRA standard, or a "measuring rim" in the ETRTO standard. A standard internal pressure is the "maximum air pressure" in the JATMA standard, the "maximum value" listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the TRA standard, or the "inflation pressure" in the ETRTO standard.

[0012] FIG. 1 is a partial development of a tread 12 of a tire 10 according to one embodiment, and FIG. 2 is a cross-sectional view showing the external shape of the tread 12. In the drawings, the symbol CL indicates the tire equatorial plane corresponding to the tire widthwise center. The symbol WD indicates the tire width direction (also referred to as the tire axial direction), with the inner side in the tire width direction WD referring to a direction approaching the tire equatorial plane CL, and the outer side in the tire width direction WD referring to a direction away from the tire equatorial plane CL. The symbol CD indicates the tire circumferential direction, which is a circumferential direction centered on the tire rotation axis. The symbol RD indicates the tire radial direction (direction perpendicular to the tire rotation axis), with the inner side in the tire radial direction RD referring to a direction approaching the tire rotation axis, and the outer side in the tire radial direction RD referring to a direction away from the tire rotation axis.

[0013] The symbol TE indicates a ground contact end of the tread 12. The ground contact end TE is the outermost position of the ground contact surface 14 in the tire width direction WD. The ground contact surface 14 refers to the surface of the tread 12 that comes into contact with the road surface when the tire is mounted on a standard rim, inflated to a standard internal pressure, placed vertically on a flat road surface, and a standard load is applied. The standard load is a load determined for each tire by each standard in the standard system including the standard on which the tire is based, and is the maximum load capacity for JATMA, the maximum value listed in the above table for TRA, and "LOAD CAPACITY" for ETRTO, but if the tire is for a passenger car, it is a load equivalent to 88% of the above load.

[0014] As shown in Fig. 1, a plurality of main grooves 16 extending in the tire circumferential direction CD are provided at intervals in the tire width direction WD on the surface of the tread 12. In this example, there are four main grooves 16, that is, a pair of center main grooves 16A, 16A located on both sides of the tire equatorial plane CL, and a pair of shoulder main grooves 16B, 16B arranged on the outer sides in the tire width direction WD, all of which are straight and extend parallel to the tire circumferential direction CD. The main grooves 16 are generally circumferential grooves having a groove width (opening width) of 5 mm or more.

[0015] A plurality of land portions 18 are defined in the tread 12 by the main grooves 16. In detail, there are provided a center land portion 18A sandwiched between a pair of center main grooves 16A, 16A, left and right intermediate land portions 18B, 18C sandwiched between the center main groove 16A and the shoulder main groove 16B, and left and right shoulder land portions 18D, 18E located outside the shoulder main groove 16B in the tire width direction WD and including the ground contact edge TE.

[0016] Each land portion 18 is provided with a plurality of lateral grooves 20 and / or sipes 22 extending in a direction intersecting the tire circumferential direction CD. Here, the sipes 22 refer to narrow grooves with a groove width of 1.5 mm or less (preferably 0.4 to 1.2 mm). The lateral grooves 20 refer to grooves with a groove width exceeding 1.5 mm (usually a groove width of 2 mm or more).

[0017] In this example, the tread pattern is asymmetric with respect to the tire equatorial plane CL, and the positions of the four main grooves 16 and the shapes and arrangements of the lateral grooves 20 and sipes 22 provided in each land portion 18 are also asymmetric, but the tread pattern is not particularly limited and may be, for example, symmetrical.

[0018] The intermediate land portion 18C and the shoulder land portion 18E on one side in the tire width direction WD are provided with straight sub-grooves 24 extending parallel to the tire circumferential direction CD. The sub-grooves 24 are narrow grooves having a groove width smaller than that of the main grooves 16, and generally have a groove width of 2.0 mm or less.

[0019] In the above-mentioned one shoulder land portion 18E, the land portion on the outer side of the secondary groove 24 in the tire width direction WD is formed as a shoulder block row 28 consisting of a plurality of shoulder blocks 26 arranged in the tire circumferential direction CD by providing lateral grooves 20A crossing the land portion at intervals in the tire circumferential direction CD. The shoulder blocks 26 extend beyond the ground contact end TE into the buttress portion 30. Each shoulder block 26 is provided with a lateral groove 20B that terminates in the buttress portion 30 on the outer side of the ground contact end TE in the tire width direction WD, and a sipe 22A that extends toward the inner side in the tire width direction WD, crosses the secondary groove 24, and further opens into the shoulder main groove 16B is connected to the tip of the lateral groove 20B.

[0020] The shoulder land portion 18D on the other side in the tire width direction WD is formed as a shoulder block row 34 consisting of a plurality of shoulder blocks 32 arranged in the tire circumferential direction CD by providing lateral grooves 20C that substantially cross the land portion at intervals in the tire circumferential direction CD. The shoulder blocks 32 extend beyond the ground contact end TE to the buttress portion 36. Each shoulder block 32 is provided with two sipes 22B that open into the shoulder main groove 16B from the outer side of the ground contact end TE in the tire width direction WD, beyond the ground contact end TE.

[0021] Here, the buttress portions 30, 36 refer to the region between the ground contact edge TE of the tread 12 and the sidewall 38, i.e., the region sandwiched between the ground contact edge TE and the outer end of the sidewall 38 in the tire radial direction RD. In this example, a ridge 40 extending over the entire circumference in the tire circumferential direction CD is provided at the boundary between the buttress portions 30, 36 and the sidewall 38. Therefore, the buttress portions 30, 36 are the region between the ground contact edge TE and the ridge 40.

[0022] 2, the meridian cross-sectional profile (the outline of the tread surface) of the tread 12 is formed in a curved shape near both sides including the ground contact edge TE. That is, some tread profiles have a shape in which the buttress portion curves downward toward the inside in the tire radial direction, with the ground contact edge as the boundary, but in this example, there is no abrupt change in shape in the profile inside and outside the ground contact edge TE, and the profile is displaced toward the inside in the tire radial direction RD in a gently curved shape.

[0023] 3 and 4, a curved recess 42 extending in the tire circumferential direction CD while being displaced outward in the tire radial direction RD is provided on the surface of the buttress portion 30. That is, the curved recess 42 extends in the tire circumferential direction CD while inclining outward in the tire radial direction RD, and terminates within the buttress portion 30.

[0024] In this example, the curved recess 42 extends in the tire circumferential direction CD while being displaced from the sidewall 38 side towards the ground contact edge TE within the buttress portion 30. That is, the curved recess 42 has a starting point within an inner region when the buttress portion 30 is divided into inner and outer halves in the tire radial direction RD, and extends in the tire circumferential direction CD while changing its position from the starting point in a direction approaching the ground contact edge TE. More specifically, the curved recess 42 extends in the tire circumferential direction CD while inclining from the inner peripheral edge of the annular buttress portion 30 (i.e., the boundary position with the sidewall 38) towards the outside in the tire radial direction RD, extends to the center of the buttress portion 30 in the tire radial direction RD, and terminates at the center.

[0025] The curved recess 42 extends in a curved manner such that, of both ends in the tire circumferential direction CD, an end 42A on the ground contact end TE side forms a smaller angle with respect to the tire circumferential direction CD than an end 42B on the sidewall 38 side. Here, the end 42A on the ground contact end TE side is, of both ends in the tire circumferential direction CD of the curved recess 42, the end closer to the ground contact end TE and the end on the outer side in the tire radial direction RD. The end 42B on the sidewall 38 side is, of both ends in the tire circumferential direction CD of the curved recess 42, the end closer to the sidewall 38 and the end on the inner side in the tire radial direction RD.

[0026] In this example, the curved recess 42 extends in the tire circumferential direction CD while being curved such that the angle with respect to the tire circumferential direction CD becomes smaller toward the side closer to the ground contact end TE. In other words, the curved recess 42 extends at an angle with respect to the tire meridian direction, and is curved such that the angle with respect to the tire meridian direction gradually increases toward the outside in the tire radial direction RD. More specifically, the angle with respect to the tire circumferential direction CD is substantially constant from the end 42B on the sidewall 38 side of the curved recess 42 to the longitudinal center, and the angle with respect to the tire circumferential direction CD becomes smaller from the longitudinal center to the tip on the ground contact end TE side.

[0027] The curved recess 42 extending in the tire circumferential direction CD has, as edges on both sides in the width direction, an outer edge 42C on the outer side in the tire radial direction RD and an inner edge 42D on the inner side in the tire radial direction RD.

[0028] The angle of the curved recess 42 with respect to the tire circumferential direction CD is not particularly limited, and may be, for example, 60° or less, or 45° or less, in the entire longitudinal direction (extension direction) of the curved recess 42. The angle θ1 with respect to the tire circumferential direction CD at the end 42A of the curved recess 42 on the ground contact end TE side may be, for example, 0° or more and 30° or less, or 0° or more and 15° or less. The angle θ2 with respect to the tire circumferential direction CD at the end 42B of the curved recess 42 on the sidewall 38 side may be, for example, 10° or more and 60° or less, or 15° or more and 45° or less.

[0029] Here, the angle of the curved recess 42 with respect to the tire circumferential direction CD is the angle between a widthwise center line 42E of the curved recess 42 and the tire circumferential direction CD on the surface of the buttress portion 30. The widthwise center line 42E is a line that bisects the curved recess 42 in its width direction (i.e., a direction perpendicular to the longitudinal direction).

[0030] The curved recess 42 is a groove that is shallower than the main groove 16 and the lateral groove 20, and its depth D1 (see FIG. 5) is not particularly limited, but may be 0.3 to 1.5 mm, or 0.5 to 1.1 mm.

[0031] The curved recess 42 is formed so that the width W1 is narrower at the end 42A on the ground contact end TE side than at the end 42B on the sidewall 38 side. In this example, the curved recess 42 is formed so that the width W1 is narrower as it approaches the ground contact end TE. That is, the width W1 of the curved recess 42 is large at the end 42B on the sidewall 38 side, and gradually decreases from the end 42B toward the ground contact end TE side, and is smallest at the end 42A on the ground contact end TE side. In this example, the end 42B on the sidewall 38 side of the curved recess 42 ends in a shape that is cut off obliquely at the boundary with the sidewall 38. Therefore, the width W1 at the end 42B is the distance in the width direction between the inner edge 42D of the curved recess 42 just before the boundary with the sidewall 38 and the outer edge 42C facing the inner edge 42D across the widthwise center line 42E.

[0032] As shown in FIGS. 3 to 5, an outer edge 42C of the curved recess 42 is provided with an inclined surface 44 that is inclined from the surface of the buttress portion 30 toward the bottom of the curved recess 42. That is, the outer edge 42C of the curved recess 42 is beveled obliquely so as to widen the opening width, thereby forming the inclined surface 44. In this example, the inclined surface 44 is provided over the entire depth direction of the curved recess 42. The inclined surface 44 may be provided over the entire outer edge 42C, but in this example, it is provided except for the end 42A on the ground contact end TE side, which has a narrow width W1. In this example, the width of the inclined surface 44 is not constant, and the width of the inclined surface 44 narrows as it approaches the end 42A on the ground contact end TE side, where the width W1 of the curved recess 42 narrows.

[0033] The curved recesses 42 are arranged side by side at intervals in the tire circumferential direction CD on the surface of the buttress portion 30. Each curved recess 42 rises in the same direction from the inner peripheral edge of the buttress portion 30 outward in the tire radial direction RD, curves, and extends in the tire circumferential direction CD.

[0034] In the curved recesses 42 adjacent to each other, the end 42A on the ground contact end TE side of one curved recess 42 and the end 42B on the sidewall 38 side of the other curved recess 42 overlap in the tire circumferential direction CD. That is, the end 42B on the sidewall 38 side of the other curved recess 42 is disposed in a position facing the end 42A on the ground contact end TE side of one curved recess 42 on the inner side in the tire radial direction RD, and both ends 42A, 42B overlap each other with a gap therebetween.

[0035] The curved recess 42 is provided extending from one shoulder block 26 over the lateral groove 20A to the other shoulder block 26 so as to straddle the adjacent shoulder blocks 26, 26 with the lateral groove 20A in between. In detail, a portion of each curved recess 42 including an end portion 42B on the sidewall 38 side extends over the entirety of one shoulder block 26 in the tire circumferential direction CD, and a portion including an end portion 42A on the ground contact edge TE side is located in the other shoulder block 26, terminating short of the lateral groove 20B located in the center of the other shoulder block 26.

[0036] While the curved recess 42 provided in the buttress portion 30 on one side in the tire width direction WD has been described above, a similar curved recess 46 is provided in the buttress portion 36 on the other side.

[0037] 1, a curved recess 46 is provided on the surface of the buttress portion 36, extending in the tire circumferential direction CD while being displaced outward in the tire radial direction RD. Of both ends in the tire circumferential direction CD, the curved recess 46 extends while being curved such that an end 46A on the ground contact end TE side forms a smaller angle with respect to the tire circumferential direction CD than an end 46B on the sidewall 38 side, and in this example, the curved recess 46 extends in the tire circumferential direction CD while being curved such that the angle with respect to the tire circumferential direction CD becomes smaller on the side closer to the ground contact end TE.

[0038] The curved recess 46 is formed so that its end 46A on the ground contact end TE side has a narrower width W1 than its end 46B on the sidewall 38 side, and in this example, the width is narrower on the side closer to the ground contact end TE. The curved recess 46 has an outer edge 46C and an inner edge 46D, and the outer edge 46C is provided with an inclined surface 48 that inclines from the surface of the buttress portion 36 toward the bottom of the curved recess 46.

[0039] The curved recesses 46 are arranged at intervals in the tire circumferential direction CD on the surface of the buttress portion 36, and an end portion 46A of one curved recess 46 on the ground contact edge TE side and an end portion 46B of the other curved recess 46 on the sidewall 38 side of the curved recess 46 overlap in the tire circumferential direction CD. The curved recesses 46 are provided extending from one shoulder block 32 across the lateral grooves 20C to the other shoulder block 32 so as to straddle the space between the adjacent shoulder blocks 32, 32.

[0040] 1, the curved recess 42 provided in the buttress portion 30 on one side and the curved recess 46 provided in the buttress portion 36 on the other side rise and extend in opposite directions in the tire circumferential direction CD from the inner circumferential edges of the buttress portions 30, 36. However, both curved recesses 42, 46 may be provided extending in the same direction.

[0041] In the above embodiment, the curved recesses 42, 46 are provided in the buttress portions 30, 36 on both sides, respectively. However, a curved recess may be provided in only one of the buttress portions.

[0042] In the tire according to the present embodiment configured as described above, by providing the curved recesses 42, 46 as described above on the surfaces of the buttress portions 30, 36, it is possible to improve the design of the buttress portions 30, 36 and thereby improve the external appearance of the pneumatic tire 10.

[0043] Furthermore, by providing the curved recesses 42, 46, it is possible to improve the resistance to external damage of the buttress portions 30, 36. That is, by providing the curved recesses 42, 46, even if a scratch is caused on the surface of the buttress portions 30, 36 by a protrusion, the scratch is less noticeable. Furthermore, the step of the curved recesses 42, 46 can stop the intrusion of a protrusion from the road surface side, thereby preventing the scratch from expanding. Furthermore, the curved recesses 42, 46 have ends 42A, 46A on the ground contact end TE side that are laid down and extend in the tire circumferential direction CD, so that a small number of recesses can be used to obtain the effect of preventing the intrusion of a protrusion over the entire tire circumferential direction CD.

[0044] Furthermore, with the curved recesses 42, 46 configured as described above, compared to a case in which recesses and protrusions extending parallel to the tire circumferential direction CD are provided, it is possible to suppress bending deformation when the steering wheel is turned, i.e., when cornering, and thus suppress wobbling.

[0045] In addition, since the ends 42B, 46B of the curved recesses 42, 46 on the sidewall 38 side overlap the ends 42A, 46A of the adjacent curved recesses 42, 46 on the ground contact edge TE side, the above-mentioned resistance to external damage and the effect of suppressing deflection during cornering can be enhanced.

[0046] In addition, the curved recesses 42, 46 are provided so as to straddle the adjacent shoulder blocks 26, 32 with the lateral grooves 20A, 20C in between, i.e., the curved recesses 42, 46 are divided by the lateral grooves 20A, 20C. Therefore, water discharged from the lateral grooves 20A, 20C can be guided to the curved recesses 42, 46 as well, improving drainage.

[0047] The appearance can be improved by providing the inclined surfaces 44, 48 on the outer edges 42C, 46C of the curved recesses 42, 46. Also, the inner edges 42D, 46D are shaped to drop in a step from the surface of the buttress portions 30, 36 (see FIG. 5), which is highly effective in stopping protrusions entering from the road surface side with the inner edges 42D, 46D. In other words, the design can be improved on the outer edges 42C, 46C side, while the inner edges 42D, 46D can be more effectively used to stop external damage.

[0048] Although several embodiments have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as the scope and spirit of the invention. [Explanation of symbols]

[0049] 10...pneumatic tire, 12...tread, 20...lateral groove, 26, 32...shoulder block, 28, 34...row of shoulder blocks, 30, 36...buttress portion, 38...sidewall, 42, 44...curved recess, 42A, 46A...end portion on ground contact end side, 42B, 46B...end portion on sidewall side, 42C, 46C...outer edge, 42D, 46D...inner edge, 44, 48...inclined surface, CD...tire circumferential direction, RD...tire radial direction, WD...tire width direction

Claims

1. a curved recess portion is provided on a surface of a buttress portion between a ground-contact end of the tread and a sidewall, the curved recess portion extending in a tire circumferential direction while being displaced toward an outer side in the tire radial direction, the curved recess portion extending in a curved manner such that an end portion on the ground-contact end side of both end portions in the tire circumferential direction forms a smaller angle with respect to the tire circumferential direction than an end portion on the sidewall side, the tread includes a shoulder block row in which shoulder blocks extending beyond the ground contact edge to the buttress portion are lined up in the tire circumferential direction, and the curved recess is provided extending from one shoulder block to the other shoulder block across the lateral groove so as to straddle between adjacent shoulder blocks with the lateral groove in between.

2. The tire according to claim 1 , wherein the curved recess is formed so that an end portion on the ground-contact end side is narrower than an end portion on the sidewall side.

3. 3. The tire according to claim 1 or 2, wherein a plurality of the curved recesses are provided at intervals in the tire circumferential direction on the surface of the buttress portion, and an end portion of one curved recess on a ground contact end side and an end portion of the other curved recess on a sidewall side of adjacent curved recesses overlap in the tire circumferential direction.

4. The tire according to any one of claims 1 to 3, wherein the curved recess includes an outer edge on an outer side in the tire radial direction and an inner edge on an inner side in the tire radial direction, and an inclined surface is provided on the outer edge that inclines from a surface of the buttress portion toward a bottom of the curved recess.

5. The tire according to any one of claims 1 to 4, wherein a meridian cross-sectional profile of the tread is formed in a curved shape in both sides adjacent to the contact edge.

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