JP7073791B2 - tire - Google Patents

Description

The present invention relates to a tire for winter, and more particularly to a tire suitable for traveling on a snowy road.

The following Patent Document 1 proposes a tire for winter in which a plurality of inclined lateral grooves, an inner joint groove, and an outer joint groove are provided in the tread portion. The inclined lateral groove extends inclined from the outside of the ground contact end to the inner end near the equator of the tire. The joint groove in the said joints between the inclined lateral grooves adjacent to each other in the tire circumferential direction on the tire equator side. The outer joint groove connects between adjacent inclined lateral grooves in the tire circumferential direction on the ground contact end side.

Japanese Unexamined Patent Publication No. 2016-196288

However, the tire of Patent Document 1 has room for further improvement in traction when traveling on snow.

The present invention has been devised in view of the above circumstances, and a main object of the present invention is to provide a tire capable of enhancing traction when traveling on snow.

The present invention is a tire having a tread portion, and the tread portion has a plurality of inclined grooves extending diagonally from a first tread end on one side in the tire axial direction toward the tire equatorial side, and a tire circumferential direction. A plurality of inclined land portions divided between the adjacent inclined grooves are provided, and the inclined land portion is provided with a plurality of joint grooves communicating between the inclined grooves, and the plurality of joint grooves are provided. , Includes an intermediate joint groove arranged between the tire equatorial line and the first tread end, the intermediate joint groove having at least one bend.

In the tire of the present invention, it is desirable that the bent portion includes two that are convex in opposite directions to each other.

In the tire of the present invention, it is desirable that the intermediate joint groove includes a pair of main inclined portions inclined in the same direction as each other and an auxiliary inclined portion forming the bent portion between the main inclined portions.

In the tire of the present invention, it is desirable that the sub-inclined portion is inclined in the direction opposite to the main inclined portion.

In the tire of the present invention, it is desirable that the sub-inclined portion is inclined in the same direction as the inclined groove.

In the tire of the present invention, it is desirable that the sub-inclined portion is inclined in the same direction as the main inclined portion.

In the tire of the present invention, it is desirable that the angle of the sub-tilted portion with respect to the tire circumferential direction is larger than the angle of the main inclined portion with respect to the tire circumferential direction.

In the tire of the present invention, it is desirable that the angle of the main inclined portion with respect to the tire circumferential direction is 45 to 55 °.

In the tire of the present invention, it is desirable that the angle of the sub-inclined portion with respect to the tire circumferential direction is 65 to 85 °.

In the tire of the present invention, it is desirable that the sub-inclined portion has a length smaller than that of the main inclined portion.

The tread portion of the tire of the present invention is divided between a plurality of inclined grooves extending diagonally from the first tread end on one side in the tire axial direction toward the tire equatorial side and the inclined grooves adjacent to each other in the tire circumferential direction. There are multiple sloping land areas. The sloping land portion is provided with a plurality of joints communicating between the sloping grooves. The plurality of seams includes an intermediate seam groove arranged between the tire equator and the end of the first tread, and the intermediate seam groove has at least one bend. Such a joint can form a hard snow pillar by a bent portion when traveling on a snowy road, and can generate a large amount of traction on snow.

It is a development view of the tread part of the tire of one Embodiment of this invention. It is an enlarged view of the 1st tread part of FIG. It is an enlarged view of the outline of the 1st intermediate joint groove. FIG. 2 is a cross-sectional view taken along the line AA of FIG. It is an enlarged view of the contour of the inclined groove, the central lateral groove and the joint groove. It is an enlarged view of the inclined land part. FIG. 6 is a cross-sectional view taken along the line BB of FIG. It is a development view of the tread part of the tire of another embodiment of this invention. It is a development view of the tread part of the tire of the comparative example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a developed view of the tread portion 2 of the tire 1 of the present embodiment. As shown in FIG. 1, the tire 1 of the present embodiment is suitably used, for example, as a winter pneumatic tire for a passenger car. In another aspect of the present invention, the tire 1 can be used, for example, as a pneumatic tire for a heavy load, a non-pneumatic tire in which the inside of the tire is not filled with pressurized air, and the like.

The tire 1 of the present embodiment includes, for example, a directional pattern in which the rotation direction R is designated. The rotation direction R is displayed by characters or symbols on the sidewall portion (not shown), for example.

The tire 1 of the present embodiment has a tread portion 2 between a first tread end Te1 and a second tread end Te2. The tread portion 2 includes a first tread portion 2A between the tire equator C and the first tread end Te1 and a second tread portion 2B between the tire equator C and the second tread end Te2. The first tread portion 2A and the second tread portion 2B are configured to be substantially line-symmetrical except that they are displaced in the tire circumferential direction. Therefore, each configuration of the first tread portion 2A can be applied to the second tread portion 2B.

In the case of a pneumatic tire, the first tread end Te1 and the second tread end Te2 are the outermost contact positions in the tire axial direction when a normal load is applied to the tire 1 in a normal state and the tire 1 touches a flat surface at a camber angle of 0 °. be. The normal state is a state in which the tire is rim-assembled on the normal rim, the normal internal pressure is filled, and there is no load. In the present specification, unless otherwise specified, the dimensions and the like of each part of the tire are values measured in a normal state.

A "regular rim" is a rim defined for each tire in the standard system including the standard on which the tire is based. For example, "standard rim" for JATMA, "Design Rim" for TRA, and ETRTO. If there is, it is "Measuring Rim".

"Regular internal pressure" is the air pressure defined for each tire in the standard system including the standard on which the tire is based. For JATTA, "maximum air pressure", for TRA, the table "TIRE LOAD LIMITS AT" The maximum value described in "VARIOUS COLD INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO.

"Regular load" is the load defined for each tire in the standard system including the standard on which the tire is based. "Maximum load capacity" for JATTA and "TIRE LOAD LIMITS" for TRA. The maximum value described in "AT VARIOUS COLD INFLATION PRESSURES", or "LOAD CAPACITY" for ETRTO.

The tread portion 2 is provided with a plurality of inclined grooves 10. The inclined groove 10 includes, for example, a first inclined groove 10A provided in the first tread portion 2A and a second inclined groove 10B provided in the second tread portion 2B. The first inclined groove 10A extends diagonally from the first tread end Te1 toward the tire equator C side. The second inclined groove 10B extends diagonally from the second tread end Te2 toward the tire equator C side. The second inclined groove 10B has substantially the same configuration as the first inclined groove 10A. Therefore, unless otherwise specified, the configuration of the first inclined groove 10A can be applied to the second inclined groove 10B. When traveling on snow, each inclined groove 10 forms a long snow column extending diagonally with respect to the tire axial direction, and by shearing this, large snow traction can be obtained.

In a preferred embodiment, the inclined grooves 10A and 10B are inclined from the tread ends Te1 and Te2 toward the tire equator C side toward the first-come-first-served side in the rotation direction R. However, the present invention is not limited to such an aspect.

FIG. 2 shows an enlarged view of the first tread portion 2A. As shown in FIG. 2, it is desirable that the inclined groove 10 is curved so that, for example, the angle θ1 with respect to the tire axial direction gradually increases toward the tire equator C side. The angle θ1 is preferably, for example, 0 to 80 °. Such an inclined groove 10 can exert a snow column shearing force also in the tire axial direction when traveling on snow.

The inclined groove 10 is interrupted without crossing the tire equator C. Therefore, the first inclined groove 10A is interrupted between the tire equator C and the first tread end Te1. The second inclined groove 10B is interrupted between the tire equator C and the second tread end Te2. In a more preferred embodiment, the ramp 10 has an inner end on the tire equator C side that breaks without connecting to other grooves. Such an inclined groove 10 is useful for maintaining rigidity near the tire equator C and improving steering stability on a dry road surface.

The distance L1 in the tire axial direction from the inner end of the inclined groove 10 (meaning the inner end of the groove center line in the tire axial direction, and the same applies hereinafter) to the equator of the tire is, for example, 2.0 of the tread width TW. It is preferably% to 7.0%. The tread width TW is the distance in the tire axial direction from the first tread end Te1 to the second tread end Te2 in the normal state.

It is desirable that the groove width of the inclined groove 10 gradually increases from the tire equator C side toward the outside in the tire axial direction, for example. The maximum groove width W1 of the inclined groove 10 is preferably, for example, 3.0% to 5.0% of the tread width TW. The depth of the inclined groove 10 is, for example, 6.0 to 12.0 mm, preferably 8.0 to 9.0 mm in the case of a winter tire for a passenger car.

The tread portion 2 of the present embodiment is provided with a plurality of central lateral grooves 12. Each of the central lateral grooves 12 crosses the tire equator C and the first end 12a communicates with the first inclined groove 10A or the second inclined groove 10B. More specifically, the central lateral groove 12 includes a first central lateral groove 12A and a second central lateral groove 12B.

The first central lateral groove 12A branches from the first inclined groove 10A, extends in the tire axial direction, and communicates with the second inclined groove 10B. The first central lateral groove 12A is inclined in the same direction as the first inclined groove 10A. More specifically, the first central lateral groove 12A is inclined in the same direction with respect to the tire axial direction from the first end communicating with the first inclined groove 10A to the second end communicating with the second inclined groove 10B. ..

The second central lateral groove 12B branches from the second inclined groove 10B, extends in the tire axial direction, and is connected to the first inclined groove 10A. The second central lateral groove 12B is inclined in the same direction as the second inclined groove 10B (shown in FIG. 1). More specifically, the second central lateral groove 12B is inclined in the same direction with respect to the tire axial direction from the first end communicating with the second inclined groove 10B to the second end communicating with the first inclined groove 10A. ..

The first central lateral groove 12A and the second central lateral groove 12B are alternately provided in the tire circumferential direction. By arranging the central lateral groove 12 in this way, a multi-directional snow column shearing force can be obtained, and by extension, excellent ice-snow road performance is exhibited.

The tread portion 2 is provided with an inclined land portion 13. The inclined land portion 13 is divided between the inclined grooves 10 adjacent to each other in the tire circumferential direction. The inclined land portion 13 of the present embodiment includes, for example, a region divided between the first central lateral groove 12A and the second central lateral groove 12B.

As shown in FIG. 1, the inclined land portion 13 is divided between, for example, a first inclined land portion 13A partitioned between a plurality of first inclined grooves 10A and a plurality of second inclined grooves 10B. Includes the second inclined land portion 13B. The second inclined land portion 13B has substantially the same configuration as the first inclined land portion 13A. Therefore, unless otherwise specified, the configuration of the first inclined land portion 13A can be applied to the second inclined land portion 13B.

As shown in FIG. 2, the inclined land portion 13 is provided with a plurality of joint grooves 15 that communicate with each other between the inclined grooves 10 adjacent to each other in the tire circumferential direction. The joint groove 15 is the inner joint groove 16 provided on the tire equator C side most, the intermediate joint groove 17 arranged on the first tread end Te1 side of the inner joint groove 16, and the most first tread end Te1 side. It includes an arranged outer joint groove 18.

It is desirable that the central lateral groove 12 and the inner joint groove 16 communicate with each other at the same position of the inclined groove 10, for example. As a result, the inner joint groove 16 is continuous with the first central lateral groove 12A via the first inclined groove 10A. Further, the end portion of the inner joint groove 16 and the end portion of the central lateral groove 12 face each other with the groove center line of the inclined groove 10 interposed therebetween. In the embodiment of "one groove is continuous with the other groove via the inclined groove", the first virtual region in which one groove is virtually extended in the length direction thereof is at least one of the ends of the other groove. A second virtual region that intersects the portion and is a virtual extension of the other groove in the length direction thereof includes an embodiment in which the second virtual region intersects with at least a part of the end portion of the one groove. In a preferred embodiment, either or both of the first virtual region and the second virtual region intersect a region that exceeds 50% of the groove width at the end. In the present embodiment, the region where the central lateral groove 12 is virtually extended intersects the entire end portion of the inner joint groove 16, while the region where the inner joint groove 16 is virtually extended is about the groove width of the end portion of the central lateral groove 12. It intersects with 50% of the area.

Such an inner joint groove 16 can form a horizontally long hard snow column by being continuous with the central lateral groove on which a large contact pressure acts, and can increase traction when traveling on snow.

It is desirable that the central lateral groove 12 has a groove width larger than, for example, the joint groove 15. In the present embodiment, the groove width W3 of the central lateral groove 12 is larger than any of the groove widths of the inner joint groove 16, the intermediate joint groove 17, and the outer joint groove 18. Such a central lateral groove 12 can form a large and hard snow column near the tire equator C where the contact pressure is high when traveling on an ice and snow road, and can provide a large snow column shearing force. On the other hand, since the inclined land portion 13 is provided with a joint groove 15 having a relatively small groove width, the inclined land portion prevents a decrease in rigidity in the vicinity of the joint groove 15 and is excessive when turning on a dry road surface. Deformation is suppressed, and as a result, steering stability on dry road surfaces can be improved.

The central lateral groove 12 of the present embodiment has, for example, a constant groove width over the entire length. Further, it is desirable that the central lateral groove 12 has a groove width W3 larger than the maximum groove width W4 of the inner joint groove 16 over the entire length. In a more preferred embodiment, the central lateral groove 12 has a groove width larger than any of the plurality of joint grooves 15. This ensures that the above-mentioned effects are exhibited.

The groove width W3 of the central lateral groove 12 is, for example, preferably 1.30 times or more, more preferably 1.40 times or more, preferably 1.70 times or less, more than the maximum groove width W4 of the inner joint groove 16. It is preferably 1.60 times or less. Such a central lateral groove 12 is useful for improving the performance of ice and snow roads and the steering stability on dry road surfaces in a well-balanced manner.

The groove width W3 of the central lateral groove 12 of the present embodiment is larger than, for example, the groove width of the inner end portion of the inclined groove 10. Further, the groove width W3 of the central lateral groove 12 is smaller than, for example, the maximum groove width W1 of the inclined groove 10. Such a central lateral groove 12 can improve the performance of ice and snow roads while suppressing uneven wear near the tire equator C.

In the present embodiment, each of the first central lateral groove 12A and the second central lateral groove 12B has the above-mentioned groove width. In a more desirable embodiment, the first central lateral groove 12A and the second central lateral groove 12B have the same groove width. Such an arrangement of the central lateral groove 12 is useful for further suppressing uneven wear near the tire equator C.

Each central lateral groove 12 extends linearly from, for example, the first end to the second end. However, the central lateral groove 12 is not limited to such an aspect. It is desirable that each of the plurality of central lateral grooves 12 is inclined at an angle θ2 of, for example, 5 to 25 ° with respect to the tire axial direction. Such a central lateral groove 12 can be expected to have a large amount of traction on snow.

As shown in FIG. 1, it is desirable that the central lateral groove 12 has a length in the tire axial direction larger than, for example, the inner joint groove 16. It is desirable that the length L9 of the central lateral groove 12 in the tire axial direction is, for example, 1.20 to 1.40 times the length L10 of the inner joint groove 16 in the tire axial direction. Such a central lateral groove 12 can enhance traction on snow while suppressing uneven wear of the land portion near the equator C of the tire.

As shown in FIG. 2, the inner joint groove 16 is located, for example, on the tire equator C side of the center position (not shown) of the first tread portion 2A in the tire axial direction. In the inner joint groove 16 of the present embodiment, for example, the distance L2 from the outer end in the tire axial direction (meaning the outer end in the tire axial direction of the groove center line, and the same applies hereinafter) to the tire equatorial line C is a tread. It is desirable that the width is 0.10 to 0.14 times the width TW.

The inner joint groove 16 extends linearly, for example. The inner joint groove 16 is arranged, for example, at an angle θ3 of 80 to 90 ° with respect to the tire circumferential direction. Such an inner joint groove 16 is useful for increasing traction on snow. When the inner joint groove 16 is inclined with respect to the tire axial direction, it is desirable that the inner joint groove 16 is inclined in the direction opposite to the inclined groove 10.

It is desirable that the angle θ11 of the inner joint groove 16 with respect to the tire axial direction is smaller than, for example, the angle θ2 of the central lateral groove 12 with respect to the tire axial direction. The difference between the angle θ2 of the central lateral groove 12 with respect to the tire axial direction and the angle θ11 of the inner joint groove 16 with respect to the tire axial direction is preferably 20 ° or less, for example. Such an inner joint groove 16 can enhance traction on snow together with the central lateral groove 12.

For example, one or a plurality of intermediate joint grooves 17 are arranged. In the present embodiment, two intermediate joint grooves 17 are provided between the inner joint groove 16 and the outer joint groove 18. The intermediate joint groove 17 includes a first intermediate joint groove 17A on the tire equator C side and a second intermediate joint groove 17B on the first tread end Te1 side. It is desirable that each intermediate joint groove 17 is inclined in the opposite direction to, for example, the inclined groove 10 that communicates with the intermediate joint groove 17.

It is desirable that each of the first intermediate joint groove 17A and the second intermediate joint groove 17B is located, for example, on the tire equator C side of the center position of the first tread portion 2A in the tire axial direction. In the present embodiment, it is desirable that the distance L3 from the outer end in the tire axial direction to the tire equator C of the first intermediate joint groove 17A is, for example, 0.14 to 0.18 times the tread width TW. In the second intermediate joint groove 17B, for example, it is desirable that the distance L4 from the outer end in the tire axial direction to the first tread end Te1 is 0.20 to 0.30 times the tread width TW. A relatively large contact pressure acts on the first intermediate joint groove 17A and the second intermediate joint groove 17B of the present embodiment when traveling on an ice-snow road, and a hard snow column can be formed.

The intermediate joint groove 17 is formed so that the angle θ4 with respect to the tire circumferential direction is smaller than that of the inner joint groove 16. The angle θ4 is an angle with respect to the tire circumferential direction of a virtual straight line connecting both ends of the groove center line. The angle θ4 of the intermediate joint groove 17 is preferably, for example, 30 to 50 °.

It is desirable that each end of the intermediate joint groove 17 of the present embodiment is displaced from the end of the intermediate joint groove 17 provided in the inclined land portion 13 adjacent to each other in the tire circumferential direction. In other words, it is desirable that a plurality of three-way junctions are formed by the intermediate joint groove 17 and the inclined groove 10. Such an intermediate joint groove 17 is useful for suppressing a decrease in rigidity of the tread portion 2 and improving steering stability on a dry road surface.

FIG. 3 shows an enlarged view of the outline of the first intermediate joint groove 17A as a diagram for explaining the intermediate joint groove 17. As shown in FIG. 3, the intermediate joint groove 17 of the present embodiment has at least one bent portion 20. In a more preferred embodiment, the bend 20 comprises, for example, two that are convex in opposite directions to each other. Such an intermediate joint groove 17 can form a hard snow pillar by a bent portion 20 when traveling on a snowy road, and can generate a large amount of traction on snow.

Further, the intermediate joint groove 17 including the bent portion 20 is easily deformed so as to be twisted with the change of the contact pressure acting on the inclined grooves 10 on both sides thereof, and by extension, the snow in the groove is effectively discharged. And the above action can be exerted for a long period of time.

The intermediate joint groove 17 has, for example, a pair of main inclined portions 21 and an auxiliary inclined portion 22 forming a bent portion 20 between them. The main inclined portion 21 extends from the inclined groove 10 at an angle θ5 of 45 to 55 ° with respect to the tire circumferential direction, for example.

The sub-inclined portion 22 is inclined in the same direction as the inclined groove 10 with which the intermediate joint groove 17 communicates, for example. Further, the sub-inclined portion 22 of the present embodiment is inclined in the direction opposite to that of the main inclined portion 21, for example. However, the sub-inclined portion 22 is not limited to such an aspect, and may be inclined in the same direction as the main inclined portion 21 as long as the bent portion 20 can be formed.

It is desirable that the angle θ6 of the sub-tilted portion 22 with respect to the tire circumferential direction is larger than, for example, the angle θ5 of the main inclined portion 21. Specifically, it is desirable that the angle θ6 of the sub-inclined portion 22 is, for example, 65 to 85 °. Such an auxiliary inclined portion 22 is useful for enhancing traction on snow.

It is desirable that the sub-inclined portion 22 has a length smaller than that of the main inclined portion 21, for example. It is desirable that the length L13 of the sub-tilted portion 22 in the tire axial direction is 0.30 to 0.50 times the length L12 of the main inclined portion 21 in the tire axial direction.

As shown in FIG. 2, the outer joint groove 18 is located, for example, on the first tread end Te1 side of the center position of the first tread portion 2A in the tire axial direction. For the outer joint groove 18, for example, it is desirable that the distance L5 from the outer end in the tire axial direction to the first tread end Te1 is 0.10 to 0.20 times the tread width TW.

The outer joint groove 18 extends linearly, for example. It is desirable that the outer joint groove 18 is inclined in the direction opposite to that of the inclined groove 10, for example. In other words, the outer joint groove 18 is inclined in the same direction as the intermediate joint groove 17. It is desirable that the outer joint groove 18 has a larger angle θ7 with respect to the tire circumferential direction than, for example, the intermediate joint groove 17. More specifically, the angle θ7 of the outer joint groove 18 is at least larger than the angle θ5 (shown in FIG. 3) of the main inclined portion 21 of the intermediate joint groove 17. In a preferred embodiment, the angle θ7 of the outer joint groove 18 is larger than the angle θ4 of the virtual straight line connecting both ends of the groove center line of the intermediate joint groove 17. As a result, the block divided by the outer joint groove 18 is likely to be appropriately deformed in the tire circumferential direction. Therefore, when traveling on an ice-snow road, the snow in the inclined groove 10 is further compacted, and excellent ice-snow road performance can be obtained.

In a more desirable embodiment, the outer joint groove 18 has a smaller angle with respect to the tire circumferential direction than the inner joint groove 16 in order to exert the above effect while maintaining steering stability on a dry road surface. The angle θ7 of the outer joint groove 18 is preferably, for example, 60 to 70 °.

It is desirable that each of the above-mentioned joint grooves 16 to 18 has, for example, a groove width W2 that is 0.20 to 0.30 times the maximum groove width W1 of the inclined groove 10. Each of the joint grooves 16 to 18 can improve steering stability on a dry road surface and ice / snow road performance in a well-balanced manner.

FIG. 4 shows a cross-sectional view taken along the line AA of the outer joint groove 18 as a diagram showing the cross-sectional shape of the joint groove 15. As shown in FIG. 4, it is desirable that the joint groove 15 has, for example, a maximum depth d2 that is 0.55 to 0.70 times the depth d1 of the inclined groove 10.

In a preferred embodiment, the joint groove 15 has a raised bottom surface at both end portions 15a in the tire axial direction. It is desirable that the depth d3 of the end portion 15a is, for example, 0.65 to 0.80 times the maximum depth d2 of the joint groove 15. Such a joint groove 15 can further improve steering stability on a dry road surface.

A more detailed configuration of each groove will be described. FIG. 5 shows an enlarged view of the contours of the inclined groove 10, the central lateral groove 12, and the joint groove 15. As shown in FIG. 5, the intersection of the groove center line of the inclined groove 10 and the extension line of the groove center line of the outer joint groove 18 connected to the first-come-first-served side of the rotation direction R of the inclined groove 10 is the first intersection 26. It is said that. In order to improve steering stability on dry road surface and ice / snow road performance in a well-balanced manner, the first distance L6 in the tire axial direction between the first tread end Te1 and the first intersection 26 is, for example, 0 of the tread width TW. It is desirable that it is .24 to 0.30 times.

The intersection of the groove center line of the inclined groove 10 and the extension line of the groove center line of the first intermediate joint groove 17A connected to the first-come-first-served side of the inclined groove 10 in the rotation direction R is defined as the second intersection 27. It is desirable that the second distance L7 in the tire axial direction between the first intersection 26 and the second intersection 27 is, for example, 0.10 to 0.17 times the tread width TW.

The intersection of the extension line of the groove center line of the first central lateral groove 12A and the groove center line of the second inclined groove 10B is defined as the third intersection point 28. It is desirable that the third distance L8 in the tire axial direction between the second intersection 27 and the third intersection 28 is, for example, 0.12 to 0.19 times the tread width TW.

The first straight line 31 extending from the intersection 10e between the first tread end Te1 and the groove center line of the inclined groove 10 to the first intersection 26 is inclined at an angle θ8 of 5 to 25 ° with respect to the tire axial direction, for example. Is desirable. As a result, the inclined groove 10 can form a long snow column in the tire axial direction, especially in the vicinity of the first tread end Te1, and thus a large snow traction can be obtained.

It is desirable that the second straight line 32 extending from the second intersection 27 to the third intersection 28 is inclined at an angle θ9 of 32 to 52 ° with respect to the tire axial direction, for example.

The intersection of the groove center line of the inclined groove 10 and the extension line of the groove center line of the central lateral groove 12 which is connected to the tire equator C side of the inclined groove 10 is defined as the fourth intersection 29. It is desirable that the third straight line 33 extending from the second intersection 27 to the fourth intersection 29 is inclined at an angle θ10 of 51 to 71 ° with respect to the tire axial direction, for example.

FIG. 6 shows an enlarged view of the inclined land portion 13. As shown in FIG. 6, the inclined land portion 13 is divided into, for example, a crown block 35, a plurality of middle blocks 36, and a shoulder block 37.

The crown block 35 includes, for example, a region divided by the inner joint groove 16 and the inclined grooves 10 on both sides, and a region divided between the first central lateral groove 12A and the second central lateral groove 12B. The crown block 35 of the present embodiment has, for example, a tread surrounded by a first edge 35a, a second edge 35b, and a third edge 35c, and the first edge 35a has, for example, a rotation direction. It is convex on the first-come-first-served side of R. The second end edge 35b is arranged on the second-end side in the rotation direction R with respect to the first end edge 35a, and is recessed on the first-come-first-served side. The third edge 35c connects the first edge 35a and the second edge 35b. As a result, the crown block 35 has a substantially U-shaped tread surface.

The crown block 35 is provided with a recess 34 recessed from the side wall on the rear arrival side in the rotation direction R to the first arrival side in the rotation direction R. The recess 34 is formed by the tip of the inclined groove 10 described above. It is desirable that the length L12 of the recess 34 in the tire circumferential direction is, for example, 0.30 to 0.50 times the length L11 of the crown block 35 in the tire circumferential direction.

It is desirable that the crown block 35 is provided with, for example, at least one crown lug sipe 38. The crown lug sipe 38 has, for example, one end communicating with one of the grooves and the other end interrupted within the block. The crown lug sipe 38 extends, for example, in the tire axial direction. Such a crown lug sipe 38 can provide frictional force, for example, on a tightly compacted snow-packed road surface while maintaining the rigidity of the crown block 35. In addition, in this specification, a sipe means a notch having a width of less than 1.5 mm.

The crown block 35 of the present embodiment is provided with, for example, a first crown lug sipe 38a, a second crown lug sipe 38b, and a third crown rug sipe 38c. The first crown lug sipe 38a extends from the first inclined groove 10A toward the second tread end Te2 side, and is interrupted in front of the recess 34, for example.

The second crown lug sipe 38b extends from the first inclined groove 10A toward the second tread end Te2 side, and has a length in the tire axial direction larger than that of the first crown lug sipe 38a, for example. The second crown lug sipe 38b of the present embodiment is interrupted, for example, on the side of the second tread end Te2 with respect to the recess 34. The third crown lug sipe 38c extends from the second inclined groove 10B toward the first tread end Te1 side, crosses the tire equator C, and is interrupted in front of the recess 34. The crown block 35 having each of the crown lug sipes 38 can prevent snow from being clogged in each inclined groove 10 in the vicinity of the tire equator C while maintaining steering stability on a dry road surface.

The middle block 36 includes, for example, a first middle block 36A, a second middle block 36B, and a third middle block 36C. The first middle block 36A is divided between, for example, the inner joint groove 16 and the first intermediate joint groove 17A. The second middle block 36B is divided between, for example, the first intermediate joint groove 17A and the second intermediate joint groove 17B. The third middle block 36C is divided between, for example, the second intermediate joint groove 17B and the outer joint groove 18.

It is desirable that each middle block 36 be provided with, for example, a middle sipe 39 that completely crosses the block. Each middle sipe 39 of the present embodiment is inclined in the same direction as, for example, the intermediate joint groove 17.

The shoulder block 37 is divided between, for example, the outer joint groove 18 and the first tread end Te1. The shoulder block 37 is provided with, for example, an outer lug groove 40 and a plurality of shoulder sipes 41.

The outer lug groove 40 extends from one of the adjacent inclined grooves 10 and is interrupted in the inclined land portion 13, for example. Such an outer lug groove 40 can enhance the ice-snow road performance while maintaining the rigidity of the shoulder block 37.

The outer lug groove 40 is inclined in the same direction as the outer joint groove 18 and extends linearly, for example. The outer lug groove 40 of the present embodiment extends along, for example, the outer joint groove 18. Such an outer lug groove 40 helps to make the rigidity distribution of the shoulder block 37 uniform and maintain steering stability on a dry road surface.

It is desirable that the outer lug groove 40 overlaps with the outer joint groove 18 in the tire axial direction, for example. This further enhances snow traction.

FIG. 7 shows a sectional view taken along line BB of the outer lug groove 40. As shown in FIG. 7, the outer lug groove 40 has, for example, a maximum depth d4 that is 0.50 to 0.65 times the depth d1 of the inclined groove 10.

It is desirable that the outer lug groove 40 has a raised bottom surface, for example, at the end portion 40a connected to the inclined groove 10. It is desirable that the depth d5 of the end portion 40a is, for example, 0.65 to 0.75 times the maximum depth d4. Such an outer lug groove 40 can maintain the rigidity of the shoulder block 37 and thus improve the steering stability on a dry road surface.

As shown in FIG. 6, the shoulder sipe 41 includes, for example, a first shoulder sipe 41A and a second shoulder sipe 41B. The first shoulder sipe 41A is provided, for example, between the outer joint groove 18 and the outer lug groove 40 and completely crosses the block. The first shoulder sipe 41A is inclined in the same direction as the outer joint groove 18, for example, and extends along the outer joint groove 18 in the present embodiment.

The second shoulder sipe 41B has, for example, one end connected to the inclined groove 10 and the other end extending to the first tread end Te1. Such a second shoulder sipe 41B can moderately relax the rigidity of the shoulder block 37 and enhance the wandering performance.

It is desirable that the second shoulder sipe 41B includes, for example, an inclined sipe portion 43 and a lateral sipe portion 44. The inclined sipe portion 43 extends diagonally from, for example, the inclined groove 10. The inclined sipe portion 43 is inclined in the same direction as the outer lug groove 40, for example, and extends along the outer lug groove 40 in the present embodiment. It is desirable that the inclined sipe portion 43 extends in a zigzag shape, for example. The inclined sipe portion 43 can maintain the apparent rigidity of the shoulder block 37 by engaging the sipe walls with each other when the tire is running.

The lateral sipe portion 44 is connected to the outer side of the inclined sipe portion 43 in the tire axial direction, and extends along the tire axial direction to the first tread end Te1. The lateral sipe portion 44 extends, for example, in a straight line. The second shoulder sipe 41B allows the lateral sipe portion 44 to undergo shear deformation in the tire axial direction of the shoulder block 37 even if the sipe walls come into contact with each other. Therefore, when traveling on an ice-snow road, snow is likely to be discharged from the inclined groove 10.

In the present embodiment, it is desirable that the sipes provided in each block are formed in a zigzag shape except for the lateral sipe portion 44 of the second shoulder sipe 41B. Such sipes can maintain the apparent rigidity of each block and thus enhance steering stability on dry road surfaces.

As shown in FIG. 1, the land ratio Lr of the tread portion 2 of the present embodiment is preferably 60% or more, more preferably 65% or more, preferably 80% or less, and more preferably 75% or less. .. As a result, steering stability on dry roads and performance on icy and snowy roads are improved in a well-balanced manner. As used herein, the "land ratio" is the ratio Sb / Sa of the actual total ground contact area Sb to the total area Sa of the virtual ground contact patch in which each groove and sipes are completely filled.

From the same viewpoint, the rubber hardness Ht of the tread rubber forming the tread portion 2 is preferably 45 ° or more, more preferably 55 ° or more, preferably 70 ° or less, and more preferably 65 ° or less. In the present specification, the "rubber hardness" is based on JIS-K6253 and is the hardness according to the durometer type A in an environment of 23 ° C.

FIG. 8 shows a developed view of the tread portion 2 of the tire 1 according to another embodiment of the present invention. In FIG. 8, the same reference numerals are given to the elements common to the above-described embodiments, and the description thereof is omitted here.

In the embodiment shown in FIG. 8, not only the intermediate joint groove 17, but also the inner joint groove 16 and the outer joint groove 18 have two bent portions that are convex in opposite directions to each other. Such an inner joint groove 16 and an outer joint groove 18 are useful for forming a hard snow column, and thus the performance of the ice-snow road is enhanced.

Although the tire of one embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment described above, and may be modified into various embodiments.

A size 205 / 55R16 pneumatic tire with the basic tread pattern of FIG. 1 was prototyped based on the specifications in Table 1. As a comparative example, as shown in FIG. 9, a tire was prototyped in which each joint groove a extends linearly and does not include a bent portion. The traction performance on snow and the steering stability on dry roads of each test tire were tested. The common specifications and test methods for each test tire are as follows.
Tread ground contact width: 160 mm
Groove depth of inclined groove: 8.5 mm
Land ratio: 70%
Rubber hardness of tread rubber Ht: 66
Land ratio: 70%
Rim: 16 x 6.5
Tire internal pressure: 200kPa
Test vehicle: Displacement 2000cc, Front-wheel drive vehicle Test tire mounting position: All wheels

<Snow traction performance>
The traction performance when driving on a snowy road with the above test vehicle was evaluated by the driver's sensuality. The result is a score with a comparative example of 100, and the larger the value, the better the traction performance on snow.

<Maneuvering stability on dry roads>
The maneuvering stability of the test vehicle when traveling on a dry road surface orbit was evaluated by the driver's sensuality. The result is a score with a comparative example of 100, and the larger the value, the better the steering stability on the dry road surface.
The test results are shown in Table 1.

As a result of the test, it was confirmed that the tire of the example exhibited excellent snow road performance. It was also confirmed that the tires of the examples maintained the steering stability on a dry road surface.

2 Tread part 10 Inclined groove 13 Inclined land part 15 Joint groove 17 Intermediate joint groove 20 Bent part C Tire equatorial Te1 1st tread end

Claims (8)

A tire with a tread
The tread portion includes a plurality of inclined grooves extending diagonally from the first tread end on one side in the tire axial direction toward the tire equator side, and a plurality of inclined grooves divided between the inclined grooves adjacent to each other in the tire circumferential direction. A sloping land area is provided,
The inclined land portion is provided with a plurality of joint grooves communicating between the inclined grooves.
The plurality of joint grooves include an intermediate joint groove arranged between the tire equator and the first tread end.
The intermediate joint groove has at least one bent portion .
The intermediate joint includes a pair of main inclined portions inclined in the same direction with each other and a sub-inclined portion forming the bent portion between the main inclined portions.
The angle of the groove center line of the main inclined portion on the acute angle side with respect to the tire circumferential direction is 45 to 55 °.
tire. The tire according to claim 1, wherein the bent portion includes two tires that are convex in opposite directions. The tire according to claim 1 or 2, wherein the sub-inclined portion is inclined in the direction opposite to that of the main inclined portion. The tire according to any one of claims 1 to 3, wherein the sub-inclined portion is inclined in the same direction as the inclined groove. The tire according to claim 1 or 2, wherein the sub-inclined portion is inclined in the same direction as the main inclined portion. 13. tire. The tire according to any one of claims 1 to 6, wherein the angle of the groove center line of the sub-inclined portion on the acute angle side with respect to the tire circumferential direction is 65 to 85 °. The tire according to any one of claims 1 to 7, wherein the sub-inclined portion has a length smaller than that of the main inclined portion.

Images