JP2021059250A - tire - Google Patents

Abstract

To provide a tire capable of exhibiting superior wet performance while maintaining driving stability and wear resistance.SOLUTION: A tire having a tread portion is provided. A plurality of curved grooves 15 having a first end 15a and a second end 15b are provided in a first middle land portion 11. Each of the first ends 15a of the plurality of curved grooves 15 communicates with a first shoulder-circumferential groove 5. Each of the second ends 15b of the plurality of curved grooves 15 communicates with another curved groove 15 adjacent in the tire circumferential direction. Each of the plurality of curved grooves 15 includes a first curved portion 16, and a second curved portion 17. An angle of the first curved portion 16 is larger than an angle of the second curved portion 17.SELECTED DRAWING: Figure 2

Description

The present invention relates to a tire.

Conventionally, various tires having improved arrangement of grooves and sipes provided on land have been proposed in order to improve steering stability and snow performance on paved roads (see, for example, Patent Document 1 below).

Japanese Unexamined Patent Publication No. 2019-6318

In recent years, as the performance of vehicles has improved, tires that exhibit better wet performance have been demanded. On the other hand, depending on the arrangement of the grooves and sipes, steering stability and wear resistance may be impaired as the wet performance is improved.

The present invention has been devised in view of the above problems, and its main object is to provide a tire capable of exhibiting excellent wet performance while maintaining steering stability and wear resistance.

The present invention is a tire having a tread portion, and the tread portion is continuous in the tire circumferential direction between the first tread end and the second tread end and the first tread end and the second tread end. The circumferential groove includes a plurality of circumferential grooves extending in the direction of the tire and a plurality of land portions divided into the circumferential grooves, and the circumferential groove includes a first shoulder circumferential groove arranged most on the end side of the first tread. The land portion includes a crown circumferential groove adjacent to the second tread end side of the first shoulder circumferential groove, and the land portion is a first middle between the first shoulder circumferential groove and the crown circumferential groove. The first middle land portion including the land portion is provided with a plurality of curved grooves having a first end and a second end, and each of the first ends of the plurality of curved grooves is the first. It communicates with one shoulder circumferential groove, and each of the second ends of the plurality of curved grooves communicates with the other curved grooves adjacent to the tire circumferential direction, and each of the plurality of curved grooves communicates with each other. The first bent portion on the first end side and the second bent portion on the second end side are included, and the angle θ1 of the first bent portion is larger than the angle θ2 of the second bent portion.

In the tire of the present invention, it is desirable that the angle θ1 and the angle θ2 are obtuse angles.

In the tire of the present invention, the bending groove is a first portion from the first end to the apex of the first bending portion, and a second portion from the apex of the first bending portion to the apex of the second bending portion. And a third portion from the apex of the second bent portion to the second end.

In the tire of the present invention, it is desirable that the second end of the curved groove communicates with the second portion of the curved groove adjacent to each other in the tire circumferential direction.

In the tire of the present invention, it is desirable that the second end of the bent groove communicates with the first bent portion side of the center position of the second portion in the length direction.

In the tire of the present invention, it is desirable that the angle θ3 between the third portion and the second portion of the curved groove with which the second end communicates is smaller than the angle θ1 and the angle θ2.

In the tire of the present invention, the angle θ3 is preferably 90 ° or less.

In the tire of the present invention, the tread portion includes a first shoulder land portion divided between the first shoulder circumferential groove and the first tread end, and the first shoulder land portion includes the first shoulder land portion. A plurality of first shoulder lateral grooves including a communication portion with the one-shoulder circumferential groove are provided, and a region extending the communication portion parallel to the tire axial direction toward the tire equatorial side overlaps with the first end of the curved groove. It is desirable to do.

In the tire of the present invention, the bending groove includes a first portion from the first end to the apex of the first bending portion, and the angle between the first shoulder lateral groove and the first portion is the angle. It is desirable that it is larger than θ1 and the angle θ2.

The first middle land portion of the tire of the present invention is provided with a plurality of curved grooves having a first end and a second end. Each of the first ends of the plurality of curved grooves communicates with the first shoulder circumferential groove. Each of the second ends of the plurality of bends communicates with the other bends adjacent in the tire circumferential direction. Such a plurality of curved grooves form non-linear grooves continuously extending in the tire circumferential direction, which is useful for enhancing wet performance.

In the present invention, the angle θ1 of the first bent portion on the first end side of the bent groove is larger than the angle θ2 of the second bent portion on the second end side. As a result, the water in the groove becomes easier to move in the first bent portion as compared with the second bent portion. Therefore, during wet running, the water in the curved groove easily moves from the second bent portion side toward the first bent portion side, and eventually the water is discharged to the first shoulder circumferential groove side. It becomes easy to be done. By demonstrating such a drainage mechanism, the present invention can improve wet performance while maintaining steering stability and wear resistance.

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 middle land part of FIG. It is an enlarged view which shows the outline of the curved groove of FIG. FIG. 2 is a cross-sectional view taken along the line AA of FIG. It is an enlarged view which shows the outline of the curved groove and the auxiliary groove of FIG. It is an enlarged view of the 2nd middle land part of FIG. FIG. 6 is a cross-sectional view taken along the line BB of FIG. FIG. 6 is a cross-sectional view taken along the line CC of FIG. It is an enlarged perspective view which shows the sipe wall of the 1st middle sipe. It is an enlarged view of the 1st shoulder land part of FIG. It is an enlarged view of the 2nd shoulder land part of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a developed view of a tread portion 2 of a tire 1 showing an embodiment of the present invention. The tire 1 of the present embodiment is suitably used as, for example, a pneumatic tire for a passenger car. However, the present invention is not limited to such an aspect, and may be used for a pneumatic tire for a heavy load or a non-pneumatic tire in which the inside of the tire is not filled with pressurized air.

As shown in FIG. 1, the tire 1 of the present embodiment has a tread portion 2 whose mounting direction on a vehicle is specified. The tread portion 2 has a first tread end Te1 located on the outside of the vehicle when the tire 1 is mounted on the vehicle, and a second tread end Te2 located on the inside of the vehicle when the tire 1 is mounted on the vehicle. The orientation of mounting on the vehicle is indicated by characters or symbols on the sidewall (not shown), for example.

In the case of a pneumatic tire, the first tread end Te1 and the second tread end Te2 are at the most outer 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 plane at a camber angle of 0 °. is there. The normal state is a state in which the tire is rim-assembled on the normal rim, the normal internal pressure is applied, 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 the 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 JATMA, "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. For JATMA, "maximum load capacity", for TRA, the table "TIRE LOAD LIMITS" The maximum value described in "AT VARIOUS COLD INFLATION PRESSURES", or "LOAD CAPACITY" for ETRTO.

The tread portion 2 includes a plurality of circumferential grooves 3 continuously extending in the tire circumferential direction between the first tread end Te1 and the second tread end Te2, and a plurality of land portions divided into these circumferential grooves 3. It is composed of 4. The tread portion 2 of the present embodiment is divided into four land portions 4 by three circumferential grooves 3. However, the tread portion 2 is not limited to such an embodiment, and the tread portion 2 may be divided into five land portions 4 by, for example, four circumferential grooves 3.

The circumferential groove 3 includes, for example, a first shoulder circumferential groove 5, a second shoulder circumferential groove 6, and a crown circumferential groove 7. The first shoulder circumferential groove 5 is arranged between the first tread end Te1 and the tire equator C, and is arranged closest to the first tread end Te1 side. The second shoulder circumferential groove 6 is arranged between the second tread end Te2 and the tire equator C, and is arranged most on the second tread end Te2 side. The crown circumferential groove 7 is arranged between the first shoulder circumferential groove 5 and the second shoulder circumferential groove 6.

The distance La in the tire axial direction from the tire equator C to the groove center line of the first shoulder circumferential groove 5 or the second shoulder circumferential groove 6 is, for example, 0.20 to 0.35 times the tread width TW. Is desirable. It is desirable that the distance Lb in the tire axial direction from the tire equatorial line C to the groove center line of the crown circumferential groove 7 is, for example, 0.15 times or less of the tread width TW. 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.

The crown circumferential groove 7 of the present embodiment is provided, for example, between the tire equator C and the second tread end Te2. However, the position of the crown circumferential groove 7 is not limited to such an aspect.

Each circumferential groove 3 of the present embodiment extends linearly in parallel with the tire circumferential direction, for example. Each circumferential groove 3 may extend in a wavy shape, for example.

The groove width Wa of each circumferential groove 3 is at least 3.0 mm or more, and is preferably 4.0% to 7.0% of the tread width TW, for example. The groove width is the distance between the groove edges in the direction orthogonal to the groove center line. The depth of each circumferential groove 3 is preferably 5 to 10 mm, for example, in the case of a pneumatic tire for a passenger car.

The land portion 4 includes a first middle land portion 11, a second middle land portion 12, a first shoulder land portion 13, and a second shoulder land portion 14. The first middle land portion 11 is divided between the first shoulder circumferential groove 5 and the crown circumferential groove 7. In the present embodiment, the first middle land portion 11 is provided on the tire equator C by the arrangement of the circumferential groove 3 described above. The second middle land portion 12 is divided between the second shoulder circumferential groove 6 and the crown circumferential groove 7. The first shoulder land portion 13 is divided between the first shoulder circumferential groove 5 and the first tread end Te1. The second shoulder land portion 14 is divided between the second shoulder circumferential groove 6 and the second tread end Te2.

FIG. 2 shows an enlarged view of the first middle land portion 11. As shown in FIG. 2, the first middle land portion 11 has, for example, the largest tire axial width W1 among the four land portions 4. Such a first middle land portion 11 has high rigidity and is useful for improving steering stability on paved roads. It is desirable that the width W1 of the first middle land portion 11 is, for example, 0.25 to 0.35 times the tread width TW (shown in FIG. 1 and the same applies hereinafter).

The first middle land portion 11 is provided with a plurality of curved grooves 15 having a first end 15a and a second end 15b. Each of the first ends 15a of the plurality of curved grooves 15 communicates with the first shoulder circumferential groove 5. Further, each of the second ends 15b of the plurality of curved grooves 15 communicates with the other curved grooves 15 adjacent to each other in the tire circumferential direction. Such a plurality of curved grooves 15 form non-linear grooves continuously extending in the tire circumferential direction, which is useful for improving wet performance.

FIG. 3 shows an enlarged view showing the outline of the curved groove 15. As shown in FIG. 3, in the present invention, the angle θ1 of the first bent portion 16 on the first end 15a side of the bent groove 15 is larger than the angle θ2 of the second bent portion 17 on the second end 15b side. As a result, the water in the groove of the first bent portion 16 can move more easily than that of the second bent portion 17. Therefore, during wet running, the water in the curved groove 15 easily moves from the second bent portion 17 side toward the first bent portion 16 side, and eventually the water moves to the first shoulder circumferential groove 5 side. It becomes easy to be discharged. In the present invention, by demonstrating such a drainage mechanism, wet performance can be improved while maintaining steering stability and wear resistance.

The angle θ1 is, for example, an obtuse angle, preferably 120 ° or more, more preferably 130 ° or more, preferably 150 ° or less, and more preferably 140 ° or less. Such a first bent portion 16 is useful for improving the wear resistance performance and the wet performance in a well-balanced manner.

From the same viewpoint, the angle θ2 is, for example, an obtuse angle, preferably 100 ° or more, more preferably 110 ° or more, preferably 160 ° or less, and more preferably 140 ° or less.

It is desirable that the radius of curvature R2 of the second bent portion 17 is larger than the radius of curvature R1 of the first bent portion 16. Such a second bent portion 17 can suppress clogging of snow inside when traveling on snow, and can sustainably exhibit excellent on-snow performance.

The curved groove 15 includes a first portion 21 from the first end 15a to the apex 16t of the first bending portion 16 and a second portion 22 from the apex 16t of the first bending portion 16 to the apex 17t of the second bending portion 17. , The third portion 23 from the apex 17t of the second bent portion 17 to the second end 15b. The apex of each bent portion means that the curvature of the groove center line of each bent portion is the maximum, and when the bent portion is bent with a constant radius of curvature, the center position in the length direction of the bent portion. Corresponds to.

The length L1 of the first portion 21 (corresponding to the so-called periferi length along the first portion 21 and the same applies hereinafter) is, for example, the width W1 of the first middle land portion 11 in the tire axial direction (FIG. It is shown in 2 and the same applies hereinafter), which is 0.30 to 0.60 times. Further, it is desirable that the first portion 21 extends with a constant groove width.

The first portion 21 is inclined at an angle of 20 to 30 ° with respect to the tire axial direction, for example. Such a first portion 21 can easily guide the water inside to the first shoulder circumferential groove 5 side during wet running.

The length L2 of the second portion 22 is larger than, for example, the length L1 of the first portion 21. Specifically, the length L2 of the second portion 22 is 2.5 to 3.5 times the length L1 of the first portion 21. Further, it is desirable that the groove width of the second portion 22 gradually increases toward the first portion 21 side. Such a second portion 22 guides the water inside to the first portion 21 side by utilizing the rotation of the tire during wet running, and thus enhances the wet performance.

The second portion 22 is inclined in the same direction as the first portion 21 with respect to the tire axial direction. The angle of the second portion 22 with respect to the tire axial direction is larger than the angle of the first portion 21 with respect to the tire axial direction. Specifically, the angle of the second portion 22 with respect to the tire axial direction is 70 to 90 °.

FIG. 4 shows a cross section of a part of the second portion 22 along the length direction thereof. FIG. 4 corresponds to a sectional view taken along line AA of the second portion 22 of FIG. As shown in FIG. 4, it is desirable that the second portion 22 is provided with a tie bar 24 having a raised groove bottom. The depth d2 of the tie bar 24 is 0.60 to 0.80 times the maximum depth d1 of the second portion 22. Such a tie bar 24 prevents the second portion 22 from opening excessively when the first middle land portion 11 touches the ground, and is useful for improving steering stability and wear resistance performance.

As shown in FIG. 3, it is desirable that the tie bar 24 is arranged on the first portion 21 side of the center position of the second portion 22 in the length direction, for example. In a more preferred embodiment, the tie bar 24 is provided at the end of the second portion 22 on the first bend 16 side.

The length L3 of the third portion 23 is smaller than, for example, the length L1 of the first portion 21 and the length L2 of the second portion 22. The length L3 of the third portion 23 is, for example, 0.30 to 0.60 times the length L1 of the first portion 21.

The third portion 23 is inclined in the direction opposite to that of the first portion 21 and the second portion 22 with respect to the tire axial direction, for example. It is desirable that the angle of the third portion 23 with respect to the tire axial direction is larger than the angle of the first portion 21 with respect to the tire axial direction and smaller than the angle of the second portion 22 with respect to the tire axial direction, for example, 40 to 50. °. As a result, during wet running, the water in the curved groove 15 is easily guided from the third portion 23 side to the first portion 21 side, and excellent wet performance can be obtained.

It is desirable that the end of the third portion 23, that is, the second end 15b of the curved groove 15, communicates with the second portion 22 of the curved grooves 15 adjacent to each other in the tire circumferential direction. More preferably, the second end 15b communicates with the first bent portion 16 side of the center position of the second portion 22 in the length direction. In the present embodiment, the above-mentioned tie bar 24 is arranged between the communication portion of the second end 15b and the first bending portion 16. This further improves wear resistance and steering stability.

The angle θ3 between the third portion 23 and the second portion 22 of the curved groove 15 through which the second end 15b communicates (hereinafter, may be referred to as “the angle of the connecting portion”) is the angle θ1 and the angle θ2. It is desirable that it is smaller than. The angle θ3 of the connecting portion is preferably 90 ° or less, more preferably 80 ° or less, preferably 45 ° or more, and more preferably 65 ° or more. As a result, when traveling on snow, a hard snow pillar is formed at the connecting portion of the two curved grooves 15, and the performance on snow is improved.

As shown in FIG. 2, the first middle land portion 11 of the present embodiment is provided with a plurality of auxiliary grooves 25.

FIG. 5 shows an enlarged view showing the contours of the curved groove 15 and the sub-groove 25. As shown in FIG. 5, the sub-groove 25 includes an inner sub-groove 26 that extends from the curved groove 15 toward the crown circumferential groove 7 side and is interrupted in the first middle land portion 11. The medial collateral groove 26 cooperates with the curved groove 15 to form a hard snow column. Further, since the medial collateral groove 26 is interrupted in the first middle land portion 11, the land portion having relatively high rigidity in the tire circumferential direction is formed in the region between the plurality of curved grooves 15 and the crown circumferential groove 7. Can be provided and steering stability on paved roads can be maintained.

The medial collateral groove 26 preferably crosses the tire equator C. Further, it is desirable that the groove width of the medial collateral groove 26 gradually decreases toward the crown circumferential groove 7 side. Such an inner sub-groove 26 facilitates the formation of a hard snow column.

The maximum depth of the medial collateral groove 26 is, for example, 0.80 to 0.90 times the maximum depth of the curved groove 15. Further, it is desirable that the depth of the medial collateral groove 26 gradually decreases from the curved groove 15 side toward the interrupted end side of the medial collateral groove 26. Such an inner sub-groove 26 is useful for improving steering stability and snow performance in a well-balanced manner.

The inner sub-groove 26 includes a first inner sub-groove 27 and a second inner sub-groove 28 that is interrupted on the first shoulder circumferential groove 5 side of the first inner sub-groove 27. The first inner sub-groove 27 communicates with, for example, the second bent portion 17 of the bent groove 15. The second inner sub-groove 28 communicates between the first bent portion 16 and the second bent portion 17, that is, the second portion 22 of the bent groove 15.

The length L4 of the first inner sub-groove 27 in the tire axial direction and the length L5 of the second inner sub-groove 28 in the tire axial direction are, for example, 0 of the width W1 of the first middle land portion 11 in the tire axial direction. .20 to 0.35 times.

The first inner sub-groove 27 and the second inner sub-groove 28 are inclined in the same direction with respect to the tire axial direction. In the present embodiment, the first inner sub-groove 27 and the second inner sub-groove 28 are inclined in the same direction as the first portion 21 of the curved groove 15.

The first inner sub-groove 27 and the second inner sub-groove 28 are inclined at an angle of 20 to 50 ° with respect to the tire axial direction, for example. In a more desirable embodiment, the angle of the second inner sub-groove 28 with respect to the tire axial direction is larger than the angle of the first inner sub-groove 27 with respect to the tire axial direction. The difference in angle between the first inner sub-groove 27 and the second inner sub-groove 28 with respect to the tire axial direction is, for example, 15 ° or less. Such a first inner sub-groove 27 and a second inner sub-groove 28 are useful for suppressing uneven wear of the first middle land portion 11.

The angle θ4 between the first medial collateral groove 27 and the second portion 22 of the curved groove 15 is preferably 100 ° or more, more preferably 120 ° or more, preferably 160 ° or less, and more preferably 140 ° or less. Is. Further, the angle θ5 between the second medial collateral groove 28 and the second portion 22 of the curved groove 15 is preferably 25 ° or more, more preferably 35 ° or more, preferably 55 ° or less, more preferably 45 °. It is below °. As a result, a hard snow column is formed at the communicating portion between the curved groove 15 and the medial collateral groove 26, and excellent on-snow performance is exhibited.

The sub-groove 25 of the present embodiment includes, for example, an outer sub-groove 30. The outer sub-groove 30 extends from the curved groove 15 to the first shoulder circumferential groove 5 side and is interrupted in the first middle land portion 11, for example. Such an outer sub-groove 30 can provide a land portion having a relatively high rigidity in the tire circumferential direction in the first middle land portion 11, and can perform on snow while maintaining steering stability on a paved road. Can be enhanced.

The outer sub-groove 30 of the present embodiment communicates with, for example, the second portion 22 of the curved groove 15. In a preferred embodiment, the end of the outer sub-groove 30 on the curved groove 15 side is the end of the inner sub-groove 26 (in the present embodiment, the second inner sub-groove 28) via the curved groove 15 on the curved groove 15 side. It faces the part in the tire axial direction. Such an inner sub-groove 26 and an outer sub-groove 30 can form a harder snow column at a portion communicating with the curved groove 15, and can further improve the performance on snow.

The fact that the two ends face each other in the tire axial direction means that one end overlaps at least a part of a region in which the other end extends parallel to the tire axial direction. Therefore, the end portion of the outer sub-groove 30 on the curved groove 15 side overlaps with at least a part of the region in which the end portion of the inner sub-groove 26 on the curved groove 15 side is extended in parallel with the tire axial direction.

The outer sub-groove 30 includes a lateral groove portion 31 extending from the curved groove 15 in the tire axial direction, and a vertical groove portion 32 connected to the lateral groove portion 31 and extending in the tire circumferential direction. Such an outer sub-groove 30 is useful for improving turning performance on a snowy road.

The medial collateral groove 26 and the lateral groove portion 31 are inclined in the same direction with respect to the tire axial direction. It is desirable that the angle θ6 of the lateral groove portion 31 with respect to the tire axial direction is smaller than, for example, the angle of the medial collateral groove 26 with respect to the tire axial direction. The angle θ6 of the lateral groove portion 31 is, for example, 20 to 30 °. The angle θ7 between the lateral groove portion 31 and the second portion 22 of the curved groove 15 is, for example, 120 to 140 °. Such a lateral groove portion 31, together with the medial collateral groove 26, provides traction on a snowy road.

The length L6 of the lateral groove portion 31 in the tire axial direction is, for example, 0.25 to 0.35 times the width W1 of the first middle land portion 11 in the tire axial direction. It is desirable that the length L6 of the lateral groove portion 31 is larger than the length of the inner sub-groove 26 in the tire axial direction. Such a lateral groove portion 31 enhances steering stability and snow performance in a well-balanced manner.

From the same viewpoint, the total length L7 of the lateral groove portion 31 and the second inner sub-groove 28 (the length in the tire axial direction from the end of the lateral groove portion 31 to the end of the second inner sub-groove 28) is the first. It is 0.60 to 0.70 times the width W1 of the 1-middle land portion 11 in the tire axial direction.

The vertical groove portion 32 is inclined in the same direction as the horizontal groove portion 31 with respect to the tire axial direction. As a result, the angle θ8 between the lateral groove portion 31 and the vertical groove portion 32 is an acute angle, for example, 40 to 55 °. The vertical groove portion 32 of the present embodiment extends along the second portion 22 of the curved groove 15. The angle difference between the flute portion 32 and the second portion 22 with respect to the tire circumferential direction is 5 ° or less. Such a flute portion 32 enhances turning performance on a snowy road while maintaining wear resistance.

The maximum depth of the outer sub-groove 30 is, for example, 0.80 to 0.90 times the maximum depth of the curved groove 15. It is desirable that the depth of the outer sub-groove 30 gradually decreases from the curved groove 15 toward the break end of the vertical groove portion 32. Such an outer sub-groove 30 helps maintain steering stability and wear resistance.

As shown in FIG. 2, a plurality of sipes 34 are provided in the first middle land portion 11 of the present embodiment. In addition, in this specification, a "sipe" is a notch having a width of 1.5 mm or less.

The sipe 34 includes, for example, an inner break sipe 35. The inner interrupted sipe 35 extends from the crown circumferential groove 7 and is interrupted in the first middle land portion 11 without communicating with the curved groove 15. The medial break sipe 35 provides frictional force by its edges, further enhancing on-snow performance on relatively tight and tight snow-packed roads. Further, since the inner interrupted sipe 35 is interrupted in the first middle land portion 11, the land portion having relatively high rigidity in the tire circumferential direction is formed in the region between the plurality of curved grooves 15 and the crown circumferential groove 7. Can be provided and steering stability on paved roads can be maintained.

The inner interrupted sipe 35 is inclined with respect to the tire axial direction, for example. The medial collateral sipe 35 of the present embodiment is inclined in the same direction as the medial collateral groove 26 with respect to the tire axial direction.

The medial interrupted sipe 35 includes, for example, a first medial interrupted sipe 36 and a second medial interrupted sipe 37 that is interrupted on the bend 15 side of the first medial interrupted sipe 36. The first medial interrupted sipe 36 of the present embodiment is interrupted on the crown circumferential groove 7 side of the tire equator C, and the second medial interrupted sipe 37 crosses the tire equator C, for example. Such a first inner interrupted sipe 36 and a second inner interrupted sipe 37 exhibit an excellent edge effect while maintaining wear resistance.

The length of the second inner interrupted sipe 37 in the tire axial direction is, for example, 1.5 to 2.5 times the length of the first inner interrupted sipe 36 in the tire axial direction.

The first medial interrupted sipe 36 and the second medial interrupted sipe 37 are inclined at an angle of, for example, 30 to 40 ° with respect to the tire axial direction. Further, the first medial interrupted sipe 36 and the second medial interrupted sipe 37 extend in parallel with each other. Such a first medial interrupted sipe 36 and a second medial interrupted sipe 37 are useful for suppressing uneven wear of the first middle land portion 11.

The sipe 34 includes, for example, a through sipe 38 extending from the crown circumferential groove 7 to the curved groove 15. The penetrating sipe 38 is inclined in the same direction as the inwardly interrupted sipe 35 with respect to the tire axial direction, for example. In a more preferred embodiment, the penetrating sipe 38 and the medial interrupted sipe 35 are arranged parallel to each other. The penetrating sipe 38 can further improve the performance on snow.

The sipe 34 includes, for example, a plurality of laterally interrupted sipe 40s. The outer interrupted sipe 40 is arranged between the curved groove 15 and the first shoulder circumferential groove 5, and one end thereof is interrupted in the first middle land portion 11.

The outer interrupted sipe 40 is inclined in the same direction as the inner interrupted sipe 35 with respect to the tire axial direction, for example. The angle of the outer interrupted sipe 40 with respect to the tire axial direction is, for example, 30 to 40 °.

The outer break sipe 40 includes, for example, a first outer break sipe 41 and a second outer break sipe 42 that extend from the bend 15 and break within the first middle land portion 11. The second outer interrupted sipe 42 is interrupted on the first shoulder circumferential groove 5 side of the first outer interrupted sipe 41. Further, the length of the second outer interrupted sipe 42 in the tire axial direction is smaller than the length of the lateral groove portion 31 of the outer sub-groove 30 in the tire axial direction. The first outer interrupted sipe 41 and the second outer interrupted sipe 42 help to improve steering stability and snow performance in a well-balanced manner.

The outer break sipe 40 includes, for example, a third outer break sipe 43 and a fourth outer break sipe 44 that extend from the first shoulder circumferential groove 5 and break within the first middle land portion 11. The fourth outer interrupted sipe 44 is interrupted on the curved groove 15 side of the third outer interrupted sipe 43. Further, the length of the fourth outer interrupted sipe 44 in the tire axial direction is the longest among the outer interrupted sipe 40.

The sipe 34 of the present embodiment includes, for example, a connecting sipe 45 extending from the first shoulder circumferential groove 5 to the outer sub-groove 30. Such a connecting sipe 45 can prevent the outer sub-groove 30 from being clogged with snow, and is useful for exhibiting excellent on-snow performance for a long period of time.

FIG. 6 shows an enlarged view of the second middle land portion 12. As shown in FIG. 6, the width W2 of the second middle land portion 12 in the tire axial direction is, for example, 0.10 to 0.20 times the tread width TW.

The second middle land portion 12 includes a plurality of middle lateral grooves 47 that completely cross the second middle land portion 12, and a plurality of middle blocks 48 that are divided into a plurality of middle lateral grooves 47.

The middle lateral groove 47 is inclined at an angle θ9 of 30 to 60 ° with respect to the tire axial direction, for example. However, the middle lateral groove 47 is not limited to such an aspect.

The middle block 48 includes two first middle sipe 51 communicating with the second shoulder circumferential groove 6 and a second middle sipe 52 arranged between the two first middle sipe 51. The first middle sipe 51 extends in a zigzag shape, for example, in a tread plan view. The second middle sipe 52 extends linearly, for example, in a tread plan view. These sipes provide the frictional force of their edges and help improve on-snow performance.

FIG. 7 shows a sectional view taken along line BB of the first middle sipe 51. As shown in FIG. 7, in the present embodiment, the first middle sipe 51 extends in a wavy shape in the depth direction thereof. The first middle sipe 51 is useful for maintaining the wear resistance performance by increasing the apparent rigidity of the middle block 48 by engaging the sipe walls facing each other during driving and braking.

FIG. 8 shows a sectional view taken along line CC of the second middle sipe 52. As shown in FIG. 8, in the present embodiment, the second middle sipe 52 extends linearly in the depth direction thereof. Since the second middle sipe 52 is easier to open than the first middle sipe 51, a large ground pressure is likely to act, and the road surface can be scratched with a stronger force.

As shown in FIG. 6, since the second middle sipe 52 of the present embodiment extends from the second shoulder circumferential groove 6 and is interrupted in the second middle land portion 12, the middle block 48 has rigidity in the tire circumferential direction. Provides a relatively high land area and can maintain wear resistance.

FIG. 9 shows an enlarged perspective view showing the sipe wall 51a of the first middle sipe 51. As shown in FIG. 9, the first middle sipe 51 is configured as a so-called 3D sipe that undulates in the depth direction and the length direction of the sipe. In such a sipe, the sipe walls facing each other can be firmly engaged with each other, and the above-mentioned effect can be further enhanced.

As shown in FIG. 6, the amplitude amount A1 (the peak-to-peak amplitude amount, the same applies hereinafter) of the first middle sipe 51 in the tread plan view is, for example, 1.0 to 3.5 mm. , Desirably 1.5 to 3.0 mm. As a result, molding defects during tire vulcanization are suppressed, and sipe opening is suppressed.

As shown in FIG. 7, the amplitude amount A2 of the first middle sipe 51 in the cross section orthogonal to the length direction of the sipe is, for example, 0.5 to 2.5 mm, preferably 1.0 to 2.0 mm. is there.

As shown in FIG. 6, the first middle sipe 51 and the second middle sipe 52 are inclined with respect to the tire axial direction. In the present embodiment, the first middle sipe 51 and the second middle sipe 52 are inclined in the same direction as the middle lateral groove 47 with respect to the tire axial direction. The angles of the first middle sipe 51 and the second middle sipe 52 with respect to the tire axial direction are, for example, 30 to 60 °, preferably 35 to 50 °.

The middle block 48 of the present embodiment is provided with a plurality of middle short grooves 53 extending from the crown circumferential groove 7 and interrupted in the middle block 48. Further, the first middle sipe 51 communicates with the middle short groove 53. The length L8 of the first middle sipe 51 in the tire axial direction is 0.70 to 0.90 times the width W2 of the second middle land portion 12 in the tire axial direction.

The second middle sipe 52 is interrupted on the crown circumferential groove 7 side of the center position of the second middle land portion 12 in the tire axial direction. The length L9 of the second middle sipe 52 in the tire axial direction is smaller than the length L8 of the first middle sipe 51 in the tire axial direction. The length L9 of the second middle sipe 52 is 0.50 to 0.70 times the width W2 of the second middle land portion 12 in the tire axial direction. Such a second middle sipe 52 enhances wear resistance and snow performance in a well-balanced manner.

FIG. 10 shows an enlarged view of the first shoulder land portion 13. As shown in FIG. 10, the first shoulder land portion 13 is provided with a plurality of first shoulder lateral grooves 55. The first shoulder lateral groove 55 extends from the first tread end Te1 to the first shoulder circumferential groove 5. As a result, the first shoulder lateral groove 55 includes the communication portion 55a with the first shoulder circumferential groove 5.

The first shoulder lateral groove 55 is inclined in the direction opposite to the first portion 21 of the curved groove 15 with respect to the tire axial direction, for example. The angle of the first shoulder lateral groove 55 with respect to the tire axial direction is, for example, 5 to 15 °. Such a first shoulder lateral groove 55 enhances traction performance when traveling on snow.

For at least one of the first shoulder lateral grooves 55, a region extending the communication portion 55a with the first shoulder circumferential groove 5 parallel to the tire axial direction toward the tire equator C side overlaps with the first end 15a of the curved groove 15. It is desirable to do. As a result, when traveling on snow, a hard snow pillar is formed by the first shoulder circumferential groove 5, the first portion 21 of the curved groove 15, and the communication portion 55a, and excellent snow performance is exhibited.

It is desirable that the angle θ10 between the first shoulder lateral groove 55 and the first portion 21 of the bent groove 15 is larger than the angle θ1 of the first bent portion 16 and the angle θ2 of the second bent portion 17. The angle θ10 is preferably 140 ° or more, more preferably 145 ° or more, preferably 165 ° or less, and more preferably 155 ° or less. As a result, not only traction performance but also turning performance is improved when traveling on snow.

The first shoulder land portion 13 is provided with, for example, a plurality of shoulder sipes 56 extending in a zigzag shape in the tire axial direction. Such a shoulder sipe 56 can improve wet performance and snow performance while maintaining the rigidity of the first shoulder land portion 13.

FIG. 11 shows an enlarged view of the second shoulder land portion 14. As shown in FIG. 11, the second shoulder land portion 14 is provided with a plurality of second shoulder lateral grooves 58 extending from the second shoulder circumferential groove 6 to the second tread end Te2.

The second shoulder lateral groove 58 includes a communication portion 58a with the second shoulder circumferential groove 6. For at least one of the second shoulder lateral grooves 58, a region extending the communication portion 58a parallel to the tire axial direction toward the tire equator overlaps with the end of the middle lateral groove 47 on the second shoulder circumferential direction groove 6 side. Such an arrangement of the second shoulder lateral groove 58 is useful for enhancing the performance on snow.

It is desirable that the angle θ11 between the second shoulder lateral groove 58 and the middle lateral groove 47 is smaller than, for example, the angle θ10 between the first shoulder lateral groove 55 and the first portion 21 of the curved groove 15. Specifically, the angle θ11 is 130 to 150 °. As a result, the second shoulder circumferential groove 6 is less likely to be clogged with snow, and excellent on-snow performance is continuously exhibited.

The second shoulder land portion 14 is provided with, for example, a first shoulder sipe 61, a second shoulder sipe 62, and a third shoulder sipe 63. The first shoulder sipe 61 extends from the second shoulder circumferential groove 6 to the second tread end Te2. The second shoulder sipe 62 extends from the second shoulder circumferential groove 6 and is interrupted within the second shoulder land portion 14. The third shoulder sipe 63 extends from the second tread end Te2 and is interrupted within the second shoulder land portion 14. It is desirable that the break of the second shoulder sipe 62 and the break of the third shoulder sipe 63 face each other via the first shoulder sipe 61. Such a second shoulder sipe 62 enhances wet performance and snow performance.

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 to various embodiments.

A size 215 / 60R16 tire having the basic pattern shown in FIG. 1 was prototyped. As a comparative example, a tire having the same angle θ1 as the angle θ2 was prototyped. The tires of the comparative examples have substantially the same pattern as that shown in FIG. 1, except for the above items. The wet performance, steering stability, wear resistance and snow performance of each test tire were tested. The common specifications and test methods for each test tire are as follows.
Mounting rim: 16 x 6.5
Tire internal pressure: 240kPa
Test vehicle: Displacement 2500cc, front-wheel drive vehicle Tire mounting position: All wheels

<Wet performance>
The performance of the test vehicle when traveling on a wet road surface 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 wet performance.

<Maneuvering stability>
The steering stability of the test vehicle when traveling on a paved road 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.

<Abrasion resistance>
The remaining groove depth of the crown circumferential groove was measured when the test vehicle traveled a certain distance. The result is an index with Comparative Example as 100, and the larger the value, the larger the remaining groove depth of the crown circumferential groove, and the better the wear resistance performance.

<Performance on snow>
The performance of the test vehicle when traveling on a snowy road 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 performance on snow.
The test results are shown in Tables 1 and 2.

As a result of the test, it was confirmed that the tire of the example improved the wet performance while maintaining the steering stability and the wear resistance performance. It was also confirmed that the tires of the examples exhibited excellent on-snow performance.

2 Tread part 5 1st shoulder circumferential groove 11 1st middle land part 15 Curved groove 15a 1st end 15b 2nd end 16 1st bent part 17 2nd bent part Te1 1st tread end θ1 Angle θ2 Angle

Claims (9)

A tire with a tread
The tread portion includes a plurality of circumferential grooves extending continuously in the tire circumferential direction between the first tread end and the second tread end, the first tread end and the second tread end, and the circumferential groove. Including multiple treads divided into
The circumferential groove includes a first shoulder circumferential groove arranged most on the first tread end side, and a crown circumferential groove adjacent to the second tread end side of the first shoulder circumferential groove.
The land portion includes a first middle land portion between the first shoulder circumferential groove and the crown circumferential groove.
The first middle land portion is provided with a plurality of curved grooves having a first end and a second end.
Each of the first ends of the plurality of curved grooves communicates with the first shoulder circumferential groove.
Each of the second ends of the plurality of bends communicates with the other bends adjacent in the tire circumferential direction.
Each of the plurality of bending grooves includes the first bending portion on the first end side and the second bending portion on the second end side.
The angle θ1 of the first bent portion is larger than the angle θ2 of the second bent portion.
tire. The tire according to claim 1, wherein the angle θ1 and the angle θ2 are obtuse angles. The bending groove includes a first portion from the first end to the apex of the first bending portion, a second portion from the apex of the first bending portion to the apex of the second bending portion, and the second bending portion. The tire according to claim 1 or 2, which includes a third portion from the apex of the portion to the second end. The tire according to claim 3, wherein the second end of the curved groove communicates with the second portion of the curved groove adjacent to each other in the tire circumferential direction. The tire according to claim 4, wherein the second end of the bent groove communicates with the first bent portion side of the center position of the second portion in the length direction. The tire according to claim 5, wherein the angle θ3 between the third portion and the second portion of the curved groove with which the second end communicates is smaller than the angle θ1 and the angle θ2. The tire according to claim 6, wherein the angle θ3 is 90 ° or less. The tread portion includes a first shoulder land portion divided between the first shoulder circumferential groove and the first tread end.
The first shoulder land portion is provided with a plurality of first shoulder lateral grooves including a communication portion with the first shoulder circumferential groove.
The tire according to any one of claims 1 to 7, wherein the region extending the communication portion parallel to the tire axial direction toward the tire equator overlaps with the first end of the curved groove. The curved groove includes a first portion from the first end to the apex of the first curved portion.
The tire according to claim 8, wherein the angle between the first shoulder lateral groove and the first portion is larger than the angle θ1 and the angle θ2.

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