JP6816506B2 - tire - Google Patents

Description

The present invention relates to a tire having excellent ice and snow performance.

For example, Patent Document 1 below proposes a tire having a land portion divided by a main groove extending linearly and a main groove extending in a zigzag shape. The land portion of the tire of Patent Document 1 is provided with a narrow groove or a vertical sipe extending in a straight line.

However, the tire of Patent Document 1 has room for further improvement in terms of improvement in performance on ice and snow.

Japanese Unexamined Patent Publication No. 2005-280457

The present invention has been devised in view of the above problems, and a main object of the present invention is to provide a tire having excellent performance on ice and snow.

The present invention is a tire having a tread portion, and the tread portion includes a first crown main groove and a second crown main groove continuously extending in the tire circumferential direction, the first crown main groove and the second crown. A crown land portion is provided between the crown main groove, and the first crown main groove and the second crown main groove have a zigzag shape in which the phases are aligned with each other, and the crown land portion has a zigzag shape. A crown vertical sipe extending in a zigzag shape in the tire circumferential direction is provided in a phase opposite to that of the first crown main groove and the second crown main groove.

In the tire of the present invention, the crown land portion includes a plurality of first crown lug grooves extending from the first crown main groove to the second crown main groove side and interrupted in the crown land portion, and the second crown main groove. A plurality of second crown lug grooves extending from the groove to the first crown main groove side and interrupting in the land portion of the crown are provided, and the crown vertical sipe extends from the first crown lug groove to the second crown lug groove. The crown land portion was divided into a first crown block divided by the crown vertical sipe and the plurality of first crown lug grooves, and the crown vertical sipe and the plurality of second crown lug grooves. It is desirable to include a second crown block.

In the tire of the present invention, it is desirable that the first crown block and the second crown block are provided with a plurality of crown transverse groove pairs composed of two crown transverse grooves that completely cross the entire width of the block.

In the tire of the present invention, the first crown block and the second crown block each have a plurality of small block pieces divided between the crown lateral narrow groove pairs, and the small block pieces are the first. A first small block piece provided at the center of one crown block or the second crown block in the tire circumferential direction, and a second small block piece having a length larger in the tire axial direction than the first small block piece. It is desirable that the first small block piece formed on the first crown block is adjacent to the second small block piece formed on the second crown block via the crown vertical sipe.

In the tire of the present invention, the crown vertical sipe has a first top portion that is convex toward the first crown main groove side and a second top portion that is convex toward the second crown main groove side, and the crown lateral side. It is desirable that at least one of the groove pairs communicates with both sides of the first top or the second top in the tire circumferential direction.

In the tire of the present invention, at least one of the crown transverse grooves provided in the first crown block is smoothly provided through the crown transverse grooves and the crown longitudinal sipe provided in the second crown block. It is desirable that it is continuous.

In the tire of the present invention, the minimum distance between the edges of the two crown lateral grooves is preferably 2.0 to 5.0 mm.

In the tire of the present invention, the crown transverse groove has an outer portion on the tread side and an inner portion provided inside the outer portion in the radial direction of the tire and extending with a constant width of less than 1.5 mm in the cross section. It is desirable to include it.

In the tire of the present invention, it is desirable that the crown lateral narrow groove has a depth of 0.60 to 0.70 times that of the first crown main groove.

In the tire of the present invention, it is desirable that the crown transverse groove has the same depth as the crown longitudinal sipe.

In the tire of the present invention, it is desirable that the bending angle of the crown vertical sipe is smaller than the bending angle of the crown main groove.

The tread portion of the tire of the present invention has a crown divided between a first crown main groove and a second crown main groove extending continuously in the tire circumferential direction, and a first crown main groove and a second crown main groove. There is a land area. The first crown main groove and the second crown main groove have a zigzag shape in which the phases are aligned with each other. Such a first crown main groove and a second crown main groove can provide frictional force due to the edge not only in the tire axial direction but also in the tire circumferential direction, and can exhibit excellent performance on ice and snow. .. Further, in the crown land portion divided into the first crown main groove and the second crown main groove in which the phases are aligned with each other, the width in the tire axial direction is unlikely to change in the tire circumferential direction. Such a crown land portion has a small bias in rigidity, and can suppress damage such as chipping.

The land portion of the crown is provided with a vertical crown sipe extending in a zigzag shape in the tire circumferential direction in a phase opposite to that of the first crown main groove and the second crown main groove. Such a crown vertical sipe can provide a frictional force in a direction different from that of each crown main groove due to its edge, and excellent on-ice and snow performance can be obtained.

Further, by providing the crown vertical sipe having a phase opposite to that of each crown main groove, the narrow portion of the land piece divided on one side of the crown vertical sipe is divided on the other side of the crown vertical sipe. Adjacent to the wide part of the land piece. As a result, when the ground pressure acts on the tread surface, the narrow portion is supported by the large portion, so that excessive deformation of the land portion is suppressed, and a high edge is suppressed especially on a road surface covered with hard ice. It can be effective.

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 outline of the crown main groove of FIG. It is an enlarged view of the crown land part of FIG. It is an enlarged view of the 1st crown block of FIG. FIG. 4 is a cross-sectional view taken along the line AA of FIG. It is an enlarged view of the middle land part of FIG. It is an enlarged view of the 1st middle block of FIG. It is an enlarged view of the shoulder land part of FIG. FIG. 8 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 the comparative example.

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 invention can be used for various tires such as pneumatic tires for passenger cars and heavy loads, and non-pneumatic tires in which pressurized air is not filled inside the tires. The tire 1 of the present embodiment is, for example, a pneumatic tire and is preferably used as a winter tire for heavy loads.

As shown in FIG. 1, the tread portion 2 has a shoulder main groove 4 continuously extending in the tire circumferential direction on the tread end Te side and a shoulder main groove 4 continuously extending in the tire circumferential direction on the tire equator C side. A extending crown main groove 3 is provided. The shoulder main groove 4 and the crown main groove 3 extend in a zigzag shape in the tire circumferential direction. In a preferred embodiment, the shoulder main groove 4 and the crown main groove 3 are formed in a zigzag shape in which the phases are aligned with each other.

The zigzag-shaped "phase" specifies the position of a specific position of the main groove extending periodically in a zigzag shape within one cycle (hereinafter, also referred to as "one pitch"). Is what you do. Further, 1 pitch Pa is, for example, the distance in the tire circumferential direction between the vertices of the mountain portions adjacent to each other in the tire circumferential direction in one main groove. Further, with respect to the two zigzag-shaped main grooves, "aligned with each other" means that one zigzag-shaped main groove peak and valley portion is the other zigzag-shaped main groove peak and valley portion. , Means that they are in the same position in the tire circumferential direction. In this case, the above-mentioned "at the same position" means that the phase difference Pd is 10% or less, more preferably 5% or less of one pitch between the main grooves 3 and 4, in addition to the case where the positions are exactly the same. It shall include the aspect having. This is intended to allow molding errors in view of the fact that the tire is a vulcanized molded product of rubber. The phase difference Pd is defined, for example, by the distance in the tire circumferential direction between the apex 6a of the mountain portion of one main groove and the apex 6b of the mountain portion of the other main groove located closest to the apex 6a.

The "tread end Te" is the most when a normal load is applied to a tire 1 in a normal state, which is rim-assembled on a normal rim and is filled with a normal internal pressure, and is grounded on a flat surface at a camber angle of 0 degrees. This is the ground contact position on the outside in the tire axial direction. 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 JATTA, "Design Rim" for TRA, and ETRTO. If so, 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. 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.

It is desirable that the crown main groove 3 is provided at a position where the groove center line thereof is separated from the tire equator C by 0.08 to 0.15 times the tread width TW. It is desirable that the shoulder main groove 4 is provided, for example, at a position where the groove center line is separated from the tire equator C by a distance of 0.25 to 0.35 times the tread width TW. However, the arrangement of the main grooves 3 and 4 is not limited to such a range. The tread width TW is the distance in the tire axial direction between the tread end Te and Te in the normal state.

In order to improve steering stability on dry road surface and performance on ice and snow in a well-balanced manner, the groove width W1 of the crown main groove 3 and the groove width W2 of the shoulder main groove 4 are, for example, 3 to 7% of the tread width TW. Is desirable. From the same viewpoint, the groove depths of the crown main groove 3 and the shoulder main groove 4 are preferably 15 to 25 mm, for example, in the case of the heavy-duty tire of the present embodiment.

FIG. 2 shows an enlarged view of the outline of the crown main groove 3 as a diagram for explaining a more detailed configuration of the crown main groove 3 and the shoulder main groove 4. As shown in FIG. 2, it is desirable that the bending angle θ5 of the crown main groove 3 is, for example, 160 to 170 °.

The crown main groove 3 has, for example, a first groove portion 5a, a second groove portion 5b, a third groove portion 5c, and a fourth groove portion 5d that are inclined with respect to the tire circumferential direction. The second groove portion 5b is inclined in the opposite direction to the first groove portion 5a and is connected to the first groove portion 5a. The third groove portion 5c is inclined in the opposite direction to the second groove portion 5b and is connected to the second groove portion 5b. The fourth groove portion 5d is inclined in the opposite direction to the third groove portion 5c and is connected to the third groove portion 5c.

Each groove portion 5a to 5d is inclined at an angle of, for example, 5 to 15 °, more preferably 9 to 12 ° with respect to the tire circumferential direction. As a more desirable embodiment, the groove portions 5a to 5d of the present embodiment each have different angles (absolute values) with respect to the tire circumferential direction. Such a crown main groove 3 can exert a frictional force due to the edge of the groove in multiple directions.

As a more desirable embodiment, it is desirable that the difference between the maximum inclination angle and the minimum inclination angle of the first to fourth groove portions 5a to 5d with respect to the tire circumferential direction is 1.0 to 4.0 °. Such a crown main groove 3 can increase the frictional force in the tire circumferential direction while suppressing uneven wear of the edge.

As shown in FIG. 1, the crown main groove 3 includes a first crown main groove 3A provided on one side of the tire equator C and a second crown main groove 3B provided on the other side of the tire equator C. Includes. In FIG. 1, the first crown main groove 3A is provided on the left side of the tire equator C. The second crown main groove 3B is provided on the right side of the tire equator C.

The first crown main groove 3A and the second crown main groove 3B have a zigzag shape in which the phases are aligned with each other. It is desirable that the first crown main groove 3A and the second crown main groove 3B are arranged, for example, with a phase difference of 5% or less of one pitch. It is more desirable that the first crown main groove 3A and the second crown main groove 3B are arranged in exactly the same phase (phase difference is 0). Such a first crown main groove 3A and a second crown main groove 3B can provide frictional force due to an edge not only in the tire axial direction but also in the tire circumferential direction, and exhibit excellent performance on ice and snow. Can be done.

The tread portion 2 is provided with a plurality of land portions divided by main grooves 3 and 4. The land portion of the present embodiment includes, for example, a crown land portion 10, a middle land portion 11, and a shoulder land portion 12. The crown land portion 10 is divided into a first crown main groove 3A and a second crown main groove 3B. The middle land portion 11 is divided between, for example, the crown main groove 3 and the shoulder main groove 4. The shoulder land portion 12 is divided between, for example, the shoulder main groove 4 and the tread end Te.

FIG. 3 shows an enlarged view of the crown land portion 10. In FIG. 3, the grooves and sipes are lightly colored to facilitate understanding of the invention. As shown in FIG. 3, since the crown land portion 10 is divided into a first crown main groove 3A and a second crown main groove 3B which are zigzag in phase with each other, the width in the tire axial direction is the tire. It is hard to change in the circumferential direction. Such a crown land portion 10 has a small bias in rigidity, and can suppress damage such as chipping.

The land portion 10 of the crown is provided with a vertical crown sipe 15 extending in a zigzag shape. As used herein, the term "sipe" means a notch having an opening width of less than 1.5 mm on the tread.

The crown vertical sipe 15 has a first top portion 15a that is convex toward the first crown main groove 3A side and a second top portion 15b that is convex toward the second crown main groove 3B side, and these alternate in the tire circumferential direction. It is provided in. The bending angle θ1 of the first top portion 15a and the second top portion 15b is preferably, for example, 150 to 170 °, which is more desirable, in order to increase the frictional force in the tire circumferential direction while suppressing the wear of the edge and the chipping of the land portion. Is 155 to 165 °. In the present embodiment, the bending angle θ1 of the crown vertical sipe 15 is, for example, the bending angle θ1 of the crown main groove 3.

It is desirable that the crown vertical sipe 15 has, for example, a depth of 0.60 to 0.70 times that of the crown main groove 3. Such a crown vertical sipe 15 can suppress an excessive decrease in the rigidity of the crown land portion 10.

The crown vertical sipe 15 extends in a zigzag shape in the tire circumferential direction in a phase opposite to that of the first crown main groove 3A and the second crown main groove 3B. In addition, "extending in a zigzag shape in the opposite phase" means that the mountain portion of one main groove extending in a zigzag shape is aligned with the valley portion of the other main groove extending in a zigzag shape in the tire circumferential direction. To do. In this embodiment, the zigzag phase difference between the crown vertical sipe 15 and the first crown main groove 3A and the zigzag phase difference between the crown vertical sipe 15 and the second crown main groove 3B are, for example, one pitch. Includes aspects that are 10% or less. It is desirable that the crown vertical sipe 15 and the crown main grooves 3A and 3B are arranged in completely opposite phases (the phase difference is 0.5 pitch).

Such a crown vertical sipe 15 can provide a frictional force in a direction different from that of each crown main groove 3A and 3B due to its edge, and excellent on-ice and snow performance can be obtained.

Further, by providing the crown vertical sipe 15 having a phase opposite to that of each crown main groove 3A and 3B, the narrow portion 13a of the land portion 10A divided on one side of the crown vertical sipe 15 is the crown vertical. Adjacent to the wide portion 13b of the land piece 10B divided on the other side of the sipe 15. As a result, when the ground pressure acts on the tread surface, the narrow portion is supported by the large portion, so that excessive deformation of the land portion is suppressed, and a high edge is suppressed especially on a road surface covered with hard ice. Can be effective

The crown land portion 10 is provided with a plurality of crown lug grooves 17 extending from the first crown main groove 3A or the second crown main groove 3B. The crown lug groove 17 of the present embodiment is preferably provided at every 1.5 to 2.5 pitches of the crown main groove 3, for example, and is provided every two pitches in the present embodiment. The crown lug groove 17 includes, for example, a plurality of first crown lug grooves 17A and a plurality of second crown lug grooves 17B. In the present embodiment, the first crown lug groove 17A and the second crown lug groove 17B are misaligned in the tire circumferential direction.

The first crown lug groove 17A extends from the first crown main groove 3A to the second crown main groove 3B side and is interrupted in the crown land portion 10, for example. The second crown lug groove 17B extends from the second crown main groove 3B to the first crown main groove 3A side and is interrupted in the crown land portion 10, for example. In the present embodiment, the crown vertical sipe 15 extends from the first crown lug groove 17A to the second crown lug groove 17B.

The crown lug groove 17 extends linearly with a constant groove width, for example. It is desirable that the crown lug groove 17 has a groove width W3 that is 0.9 to 1.1 times that of the crown main groove 3, for example. It is desirable that the crown lug groove 17 has a groove depth 0.75 to 0.85 times that of the crown main groove 3, for example. Such a crown lug groove 17 can improve wet performance while suppressing damage to the crown land portion 10.

It is desirable that the crown lug groove 17 is arranged at an angle θ2 with respect to the tire axial direction, for example. The angle θ2 is preferably 1.0 ° or more, more preferably 2.0 ° or more, preferably 5.0 ° or less, and more preferably 4.0 ° or less. Such a crown lug groove 17 exerts a frictional force in the lateral direction as well, and can improve the lateral slip resistance performance on ice and snow. Further, such a crown lug groove 17 is likely to exert a ground pressure evenly on the entire edge, and is also useful for suppressing chipping and uneven wear of the edge.

The crown land portion 10 includes a crown block 18 separated by a crown vertical sipe 15 and a crown lug groove 17. The crown block 18 includes, for example, a first crown block 18A and a second crown block 18B. The first crown block 18A is divided into, for example, a crown vertical sipe 15 and a plurality of first crown lug grooves 17A. The second crown block 18B is divided into a crown vertical sipe 15 and a plurality of second crown lug grooves 17B.

FIG. 4 shows an enlarged view of the first crown block 18A as a diagram for explaining the configuration of the crown block 18. As shown in FIG. 4, the crown block 18 has, for example, a vertically elongated shape having a length L1 in the tire circumferential direction larger than a width W4 in the tire axial direction. Such a crown block 18 has high rigidity in the tire circumferential direction, and can exhibit a large traction on a dry road surface.

The width W4 of the crown block 18 in the tire axial direction is preferably 8 to 12% of, for example, the tread width TW (shown in FIG. 1 and the same applies hereinafter). It is desirable that the length L1 of the crown block 18 in the tire circumferential direction is, for example, 2.5 to 3.5 times the width W4. Such a crown block 18 has a good balance of rigidity in the tire circumferential direction and the tire axial direction, and can effectively suppress chipping and uneven wear of the block.

It is desirable that the crown block 18 is provided with, for example, a plurality of crown lateral groove pairs 20. The crown transverse groove pair 20 is composed of two crown transverse grooves 21 that completely cross the entire width of the block. In the present embodiment, one crown block 18 is provided with three crown transverse groove pairs 20. As a result, in the crown block 18, small block pieces 22 and large block pieces 23 are alternately divided in the tire circumferential direction.

The small block piece 22 is divided between the two crown lateral narrow grooves 21. The large block piece 23 is divided between the crown lug groove 17 and the crown lateral narrow groove pair 20 or between the crown lateral narrow groove pair 20 adjacent to each other in the tire circumferential direction. The large block piece 23 has a width in the tire circumferential direction that is larger than that of the small block piece 22. The maximum width W6 of the large block piece 23 in the tire circumferential direction is, for example, 2.5 to 3.5 times the width W5 of the small block piece 22.

In such an arrangement of the small block piece 22 and the large block piece 23, since the small block piece 22 is supported by the large block piece 23, excessive deformation of the crown block 18 can be suppressed. Therefore, more crown lateral narrow grooves 21 can be arranged, and excellent performance on ice and snow can be obtained.

As shown in FIG. 3, in a desirable embodiment, the small block pieces 22 are the first small block piece 22a provided at the center of the first crown block 18A or the second crown block 18B in the tire circumferential direction, and the first small block piece 22a. It includes a second small block piece 22b having a length larger in the tire axial direction than the small block piece 22a. It is desirable that the first small block piece 22a formed on the first crown block 18A is adjacent to the second small block piece 22b formed on the second crown block 18B via the crown vertical sipe 15. Similarly, it is desirable that the first small block piece 22a formed on the second crown block 18B is adjacent to the second small block piece 22b formed on the first crown block 18A via the crown vertical sipe 15. ..

In such an arrangement of the small block pieces 22, the second small block piece 22b supports the tilting of the first small block piece 22a in the tire axial direction, so that excessive deformation of the land portion is suppressed, which is excellent on a dry road surface. Steering stability is obtained.

As shown in FIG. 4, in a more desirable embodiment, it is desirable that the side wall of the small block piece 22 on the main groove 3 side is recessed more than the side wall of the large block piece 23. As a result, when traveling on snow, the snow can be strongly compacted in the main groove 3, and a large snow column shearing force can be obtained.

The crown transverse groove pair 20 is composed of, for example, two crown transverse grooves 21 extending in the same direction, and in a more desirable embodiment, is composed of two crown transverse grooves 21 extending in parallel with each other. ..

The minimum distance L2 between the edges of the two crown transverse grooves 21 is preferably 2.0 mm or more, more preferably 2.5 mm or more, preferably 5.0 mm or less, and more preferably 4.5 mm or less. is there. As a result, the two crown lateral narrow grooves 21 are appropriately separated from each other, so that the generation of bears and the like during vulcanization molding can be suppressed. Further, such a crown lateral narrow groove pair 20 can appropriately secure the width of the large block piece 23, and can suppress chipping and uneven wear of the block.

The crown lateral groove 21 has, for example, a width of 3 mm or less, preferably a width of 2.5 mm or less. The crown lateral groove 21 may be configured as a sipe, for example.

FIG. 5 shows a sectional view taken along line AA of the crown transverse groove pair 20. As shown in FIG. 5, the crown transverse groove 21 includes an outer portion 24 on the tread side and an inner portion 25 provided on the inner side in the tire radial direction of the outer portion 24 in the cross section.

The outer portion 24 has, for example, an opening width W11 of 1.5 to 2.5 mm. The depth d1 of the outer portion 24 is, for example, 0.5 to 1.5 mm. It is desirable that the inner portion 25 extends with a constant width of less than 1.5 mm, for example. Such outer portions 24 and inner portions 25 can provide a large frictional force by the edges while maintaining the rigidity of the crown block 18. However, the crown lateral narrow groove 21 is not limited to such an aspect, and may extend from the tread to the bottom with a constant width, for example.

The crown lateral groove 21 of the present embodiment has, for example, a first wall surface 26 and a second wall surface 27. The first wall surface 26 extends linearly from the bottom to the tread in the cross section. In the cross section, the second wall surface 27 is connected to the first portion 27a which extends linearly in the tire radial direction to form the inner portion 25 and the first portion 27a outside the tire radial direction so as to expand the groove width. It includes a second portion 27b that bends to form the outer portion 24.

In a preferred embodiment, in one crown transverse groove pair 20, the first wall surface 26 of the crown transverse grooves 21 on both sides is arranged on the small block piece 22 side between them. As a result, the side surface of the small block piece 22 is formed flat, so that the durability of the small block piece 22 can be improved.

It is desirable that the crown lateral narrow groove 21 has, for example, a depth d2 that is 0.60 to 0.70 times that of the first crown main groove 3A. In a more preferred embodiment, the crown transverse groove 21 has the same depth as the crown longitudinal sipe 15. Such a crown lateral narrow groove 21 can improve steering stability on a dry road surface and performance on ice and snow in a well-balanced manner.

As shown in FIG. 3, it is desirable that at least one of the crown lateral groove pairs 20 communicates with both sides of the first top 15a or the second top 15b of the crown vertical sipe 15 in the tire circumferential direction. More specifically, one crown lateral groove 21 of one crown lateral groove pair 20 communicates with one side of the apex of the first top portion 15a or the second top portion 15b in the tire circumferential direction, and one crown lateral groove. The other crown lateral groove 21 of the groove pair 20 communicates with the other side of the apex in the tire circumferential direction.

At least one of the crown transverse grooves 21 provided in the first crown block 18A is smoothly continuous with the crown transverse grooves 21 provided in the second crown block 18B via the crown vertical sipe 15. desirable. Since the plurality of crown lateral narrow grooves 21 are smoothly continuous, the land portion is appropriately deformed and each edge can be easily grounded uniformly, which in turn further enhances the performance on ice and snow.

In the present embodiment, of the plurality of crown transverse grooves 21 provided in one first crown block 18A, more than half are smoothly continuous with the crown transverse grooves 21 provided in the second crown block 18B. ..

It is desirable that at least one of the crown lateral narrow grooves 21 communicates with the crown lug groove 17. Such an arrangement of the crown lateral narrow grooves 21 can provide a high frictional force together with the edge of the crown lug groove 17. Further, by arranging the crown lateral narrow groove 21 in this way, the snow in the crown lug groove 17 is easily discharged by the movement of the small block piece 22, and it is possible to suppress the deterioration of the performance on ice and snow due to the clogging of the snow.

FIG. 6 shows an enlarged view of the middle land portion 11. In FIG. 6, the grooves and sipes are lightly colored to facilitate understanding of the invention. As shown in FIG. 6, the middle land portion 11 is provided with a middle vertical sipe 30 extending in a zigzag shape.

The middle vertical sipe 30 has a first top portion 30a that is convex toward the shoulder main groove 4 side and a second top portion 30b that is convex toward the crown main groove 3 side, and these are provided alternately in the tire circumferential direction. There is. It is desirable that the bending angle θ3 of the first top portion 30a and the second top portion 30b of the middle vertical sipe 30 is smaller than, for example, the bending angle θ1 (shown in FIG. 3) of the crown vertical sipe 15. Specifically, the bending angle θ3 of the middle vertical sipe 30 is preferably, for example, 140 to 160 °, and more preferably 145 to 155 °. Such a middle vertical sipe 30 is useful for increasing the frictional force in the tire circumferential direction while suppressing the wear of the edge and the chipping of the land portion.

It is desirable that the middle vertical sipe 30 has a depth smaller than, for example, the crown vertical sipe 15. Specifically, it is desirable that the middle vertical sipe 30 has a depth of 0.85 to 0.98 times that of the crown vertical sipe 15. As a result, the crown land portion 10 and the middle land portion 11 are likely to be uniformly worn.

It is desirable that the middle vertical sipe 30 extends in a zigzag shape in the tire circumferential direction in a phase opposite to that of the shoulder main groove 4 and the crown main groove 3, for example. Such a middle vertical sipe 30 can provide a frictional force in a direction different from that of the shoulder main groove 4 and the crown main groove 3, and excellent on-ice performance can be obtained. Further, the middle land portion 11 divided by the shoulder main groove 4, the crown main groove 3, and the middle vertical sipe 30 is suppressed from excessive deformation and covered with hard ice, as in the crown land portion 10. A high edge effect can be exhibited on the road surface.

The middle land portion 11 is provided with, for example, a plurality of middle lug grooves 32 extending from the shoulder main groove 4 or the crown main groove 3. The middle lug groove 32 of the present embodiment is preferably provided at every 1.5 to 2.5 pitches of the shoulder main groove 4 or the crown main groove 3, for example, and is provided every two pitches in the present embodiment. There is. The middle lug groove 32 includes, for example, a plurality of first middle lug grooves 32A and a plurality of second middle lug grooves 32B. The first middle lug groove 32A and the second middle lug groove 32B are, for example, misaligned in the tire circumferential direction.

The first middle lug groove 32A extends from the shoulder main groove 4 to the crown main groove 3 side and is interrupted in the middle land portion 11, for example. The second middle lug groove 32B extends from the crown main groove 3 to the shoulder main groove 4 side and is interrupted in the middle land portion 11, for example. In the present embodiment, the middle vertical sipe 30 extends from the first middle lug groove 32A to the second middle lug groove 32B.

The middle lug groove 32 extends linearly with a constant groove width, for example. It is desirable that the middle lug groove 32 has a groove width smaller than, for example, the crown lug groove 17 (shown in FIG. 3). It is desirable that the middle lug groove 32 of the present embodiment has, for example, a groove width W7 that is 0.80 to 0.90 times that of the crown lug groove 17. As a result, the crown land portion 10 and the middle land portion 11 are likely to be uniformly worn.

From the same viewpoint, it is desirable that the middle lug groove 32 has a groove depth smaller than, for example, the crown lug groove 17. It is desirable that the middle lug groove 32 of the present embodiment has, for example, a groove depth of 0.90 to 0.98 times that of the crown lug groove 17.

It is desirable that the first middle lug groove 32A is arranged at an angle of 10 ° or less with respect to the tire axial direction, for example. The first middle lug groove 32A of the present embodiment extends along the tire axial direction.

It is desirable that the second middle lug groove 32B is arranged at an angle θ4 larger than that of the first middle lug groove 32A with respect to the tire axial direction, for example. The angle θ4 is preferably 10 ° or more, more preferably 12 ° or more, preferably 20 ° or less, and more preferably 18 ° or less. Such a second middle lug groove 32B exerts a frictional force in the lateral direction as well, and can improve the lateral slip resistance performance on ice and snow. In such a crown lug groove 17, the ground pressure is likely to be applied evenly to the entire edge, and it is also useful for suppressing chipping and uneven wear of the edge.

The middle land portion 11 includes, for example, a middle block 33 divided by a middle vertical sipe 30 and a middle lug groove 32. The middle block 33 includes, for example, a first middle block 33A and a second middle block 33B. The first middle block 33A is divided into, for example, a middle vertical sipe 30 and a plurality of first middle lug grooves 32A. The second middle block 33B is divided into a middle vertical sipe 30 and a plurality of second middle lug grooves 32B.

FIG. 7 shows an enlarged view of the first middle block 33A as a diagram for explaining the configuration of the middle block 33. As shown in FIG. 7, the middle block 33 has, for example, a vertically elongated shape having a length L3 in the tire circumferential direction larger than a width W8 in the tire axial direction.

It is desirable that the width W8 of the middle block 33 in the tire axial direction is, for example, 8 to 12% of the tread width TW. It is desirable that the length L3 of the middle block 33 in the tire circumferential direction is, for example, 2.5 to 3.5 times the width W8. Such a middle block 33 has a good balance of rigidity in the tire circumferential direction and the tire axial direction, and can effectively suppress chipping and uneven wear of the block.

It is desirable that the middle block 33 is provided with, for example, a plurality of middle lateral narrow groove pairs 35. The middle transverse groove pair 35 is composed of two middle transverse grooves 36 that completely cross the entire width of the block. The middle transverse groove 36 has substantially the same configuration as the crown transverse groove 21 (shown in FIG. 5) in cross section, and the description thereof is omitted here. In the present embodiment, one middle block 33 is provided with three middle lateral narrow groove pairs 35. As a result, in the middle block 33, the small block piece 37 and the large block piece 38 are alternately divided in the tire circumferential direction.

The small block piece 37 is divided between the two middle lateral narrow grooves 36. The large block piece 38 is divided between the middle lug groove 32 and the middle horizontal narrow groove pair 35, or between the middle horizontal narrow groove pair 35 adjacent to each other in the tire circumferential direction. The large block piece 38 has a width in the tire circumferential direction that is larger than that of the small block piece 37. The middle block 33 having such a small block piece 37 and a large block piece 38 is suppressed from being excessively deformed like the crown block 18.

In a more desirable embodiment, it is desirable that the side wall of the small block piece 37 on the main groove side is recessed more than the side wall of the large block piece 38. As a result, when traveling on snow, the snow can be strongly compacted in the main groove, and as a result, a large snow column shearing force can be obtained.

In the middle horizontal fine groove pair 35, for example, the first middle horizontal fine groove pair 35A in which the two middle horizontal fine grooves 36 are parallel to each other and extend linearly, and the two middle horizontal fine grooves 36 are kept parallel to each other. It includes a second middle lateral groove pair 35B that bends as it is. The second middle horizontal groove pair 35B increases the frictional force in a direction different from that of the first middle horizontal narrow groove pair 35A, and by extension, excellent performance on ice and snow is exhibited.

Each middle horizontal groove 36 of the second middle horizontal groove vs. 35B of the present embodiment is, for example, a first portion 36a inclined with respect to the tire axial direction and a second portion that is bent and connected to both sides of the first portion 36a. Includes portion 36b. The second portion 36b is arranged at an angle smaller than that of the first portion 36a with respect to the tire axial direction, for example. As a result, each middle horizontal groove 36 of the second middle horizontal groove vs. 35B is bent in a substantially S shape. The width of the small block piece 37 divided by the second middle lateral narrow groove pair 35B is likely to be deformed in the tire axial direction when stress is applied in the tire circumferential direction. This helps to drain the snow in the main ditch when traveling on snow.

In order to further enhance the above-mentioned effect, in the present embodiment, the first middle lateral groove pair 35A is provided at the center of the middle block 33 in the tire circumferential direction. The second middle horizontal narrow groove pair 35B is provided on both sides of the first middle horizontal narrow groove pair 35A in the tire circumferential direction, for example.

In a preferred embodiment, in the first middle block 33A, the first portion 36a of the middle transverse groove 36 of one second middle transverse groove vs. 35B is the middle transverse groove 36 of the other second middle transverse groove vs. 35B. It is inclined in the opposite direction to the first portion 36a of. On the other hand, as shown in FIG. 6, in the second middle block 33B, the first portion 36a of the middle horizontal groove 36 of one and the other second middle horizontal groove vs. 35B is inclined in the same direction, respectively. ..

Due to the arrangement of the middle lateral groove pairs 35 described above, the first middle block 33A and the second middle block 33B are easily deformed in different modes from each other. This exerts frictional force in multiple directions due to the edges, and also helps to suppress snow clogging in the middle lug groove 32.

It is desirable that at least one of the middle lateral groove pairs 35 communicates with both sides of the first top portion 30a or the second top portion 30b of the middle vertical sipe 30 in the tire circumferential direction. More specifically, one middle horizontal groove 36 of one middle horizontal groove pair 35 communicates with one side of the apex of the first top portion 30a or the second top portion 30b in the tire circumferential direction, and the other middle horizontal groove 36 communicates with the other. The narrow groove 36 communicates with the other side of the apex in the tire circumferential direction.

At least one of the middle horizontal narrow grooves 36 provided in the first middle block 33A is smoothly continuous with the middle horizontal narrow groove 36 provided in the second middle block 33B via the middle vertical sipe 30. desirable. Since the plurality of middle lateral fine grooves 36 are smoothly continuous, the land portion is appropriately deformed, and each edge can be easily grounded uniformly, which in turn further enhances the performance on ice and snow.

In a preferred embodiment, each middle transverse groove 36 of the first middle transverse groove vs. 35A is smoothly continuous with the middle transverse groove 36 of the second middle transverse groove vs. 35B via the middle longitudinal sipe 30.

In order to further exert the above-mentioned effects, in the present embodiment, more than half of the plurality of middle lateral narrow grooves 36 provided in one first middle block 33A are middle lateral provided in the second middle block 33B. It is smoothly continuous with the fine groove 36.

FIG. 8 shows an enlarged view of the shoulder land portion 12. In FIG. 8, the grooves and sipes are lightly colored to facilitate understanding of the invention. As shown in FIG. 8, the shoulder land portion 12 is provided with, for example, a shoulder vertical sipe 40 extending in a straight line.

It is desirable that the shoulder vertical sipe 40 has a depth smaller than, for example, the crown vertical sipe 15. The shoulder vertical sipe 40 of the present embodiment has, for example, a depth of 0.99 to 0.98 times that of the crown vertical sipe 15. Such a shoulder vertical sipe 40 can make the progress of wear of the crown land portion 10 and the shoulder land portion 12 uniform.

The shoulder land portion 12 is provided with, for example, a shoulder main groove 4 or a plurality of shoulder lug grooves 42 extending from the tread end Te. The shoulder lug groove 42 of the present embodiment is preferably provided at every 1.5 to 2.5 pitches of the shoulder main groove 4, for example, and is provided every two pitches in the present embodiment. The shoulder lug groove 42 includes, for example, a plurality of first shoulder lug grooves 42A and a plurality of second shoulder lug grooves 42B. It is desirable that the first shoulder lug groove 42A and the second shoulder lug groove 42B are displaced in the tire circumferential direction, for example.

The first shoulder lug groove 42A extends from the tread end Te to the shoulder main groove 4 side and is interrupted in the shoulder land portion 12. The second shoulder lug groove 42B extends from the shoulder main groove 4 to the tread end Te side and is interrupted in the shoulder land portion 12, for example. In the present embodiment, the shoulder vertical sipe 40 extends from the first shoulder lug groove 42A to the second shoulder lug groove 42B.

It is desirable that the groove width of the first shoulder lug groove 42A gradually increases toward the tread end Te side, for example. It is desirable that the groove depth of the first shoulder lug groove 42A gradually increases toward the tread end Te side, for example. Such a first shoulder lug groove 42A is useful for guiding the water in the groove to the tread end Te side during wet running.

It is desirable that the second shoulder lug groove 42B extends with a constant groove width, for example. It is desirable that the second shoulder lug groove 42B has, for example, a groove width W9 that is 0.75 to 0.85 times that of the middle lug groove 32. Further, it is desirable that the second shoulder lug groove 42B has a groove depth 0.85 to 0.95 times that of the middle lug groove 32.

The shoulder land portion 12 includes, for example, a shoulder block 43 separated by a shoulder vertical sipe 40 and a shoulder lug groove 42. The shoulder block 43 includes, for example, a first shoulder block 43A and a second shoulder block 43B. The first shoulder block 43A is divided into, for example, a shoulder vertical sipe 40 and a plurality of first shoulder lug grooves 42A. The second shoulder block 43B is divided into a shoulder vertical sipe 40 and a plurality of second shoulder lug grooves 42B.

The shoulder block 43 has, for example, a vertically elongated shape in which the length L4 in the tire circumferential direction is larger than the width W10 in the tire axial direction. It is desirable that the width W10 of the shoulder block 43 in the tire axial direction is, for example, 8 to 12% of the tread width TW. It is desirable that the length L4 of the shoulder block 43 in the tire circumferential direction is, for example, 2.5 to 3.5 times the width W10. Such a shoulder block 43 has a good balance of rigidity in the tire circumferential direction and the tire axial direction, and can effectively suppress chipping and uneven wear of the block.

It is desirable that the shoulder block 43 is provided with, for example, a plurality of shoulder lateral groove pairs 45. The shoulder lateral groove pair 45 is composed of two shoulder lateral grooves 46 that completely cross the entire width of the block. The shoulder transverse groove 46 has substantially the same configuration as the crown transverse groove 21 in the cross section, and the description thereof is omitted here.

In the present embodiment, one shoulder block 43 is provided with two shoulder lateral groove pairs 45. As a result, the shoulder block 43 is divided into a small block piece 47 divided between the two shoulder lateral narrow grooves 46 and a large block piece 48 having a larger width in the tire circumferential direction. Like the crown block 18, such a shoulder block 43 suppresses excessive deformation.

The first shoulder block 43A is provided with a wide horizontal narrow groove 49 having a larger opening width on the tread surface than the shoulder horizontal narrow groove 46 between the two shoulder horizontal narrow grooves vs. 45.

FIG. 9 shows a sectional view taken along line BB of the wide lateral groove 49. As shown in FIG. 9, the wide lateral groove 49 is provided on the tread side with an outer portion 50 having an opening width W12 of, for example, 2.0 to 3.0 mm, and an outer portion 50 inside in the tire radial direction. It includes an inner portion 51 extending with a constant width of less than 1.5 mm. Such a wide lateral groove 49 can provide frictional force due to the edge while maintaining the rigidity of the first shoulder block 43A.

As shown in FIG. 8, the second shoulder block 43B is provided with, for example, a shoulder sipe 52 completely crossing the entire width of the block between the second shoulder lug groove 42B and the shoulder lateral narrow groove 46. The shoulder sipe 52 of the present embodiment includes, for example, a first portion 52a inclined with respect to the tire axial direction, and a second portion 52b arranged on both sides of the first portion 52a and extending in the tire axial direction. Such a shoulder sipe 52 is useful for further improving the performance on ice and snow.

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 can be modified to various embodiments.

A heavy-duty tire of size 11R22.5 having the basic pattern of FIG. 1 was prototyped based on the specifications in Table 1. As a comparative example, as shown in FIG. 10, a tire in which the crown vertical sipe and the middle vertical sipe extend linearly has been prototyped. The performance of each test tire on ice and snow, as well as the durability of the crown land, were tested. The common specifications and test methods for each test tire are as follows.
Mounting rim: 7.50 x 22.5
Tire internal pressure: 800kPa
Test vehicle: 10t truck (2-D vehicle) with 5t loading condition Tire mounting position: All wheels

<Performance on ice and snow>
The time required to travel 200 m on an S-shaped road consisting of a continuous ice road surface and a snow-packed road surface with a radius of curvature of 30 m was measured. The result is an index with the time of the comparative example as 100, and the smaller the value, the better the performance on ice and snow.

<Durability of the land part of the crown>
The number of damages such as chipping and uneven wear of the crown land part at the time when the crown land part was worn by 40% in the above test vehicle was visually measured and evaluated in the following four stages A to D.
A: No damage has occurred on the land of the crown.
B: There are 1 to 5 damages on the land of the crown.
C: There are 6 to 10 damages on the land of the crown.
D: There are 11 or more damages on the land of the crown.
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 performance on ice and snow. In addition, it was confirmed that the tires of the examples had improved durability in the land area of the crown.

2 Tread part 3A 1st crown main groove 3B 2nd crown main groove 10 Crown land part 15 Crown vertical sipe

Claims (11)

A tire with a tread
The tread portion includes a first crown main groove and a second crown main groove that extend continuously in the tire circumferential direction, and a crown land portion divided between the first crown main groove and the second crown main groove. And are provided,
The first crown main groove and the second crown main groove have a zigzag shape in which the phases are aligned with each other.
In the land portion of the crown, a crown vertical sipe extending in a zigzag shape in the tire circumferential direction in a phase opposite to that of the first crown main groove and the second crown main groove, and the second crown from the first crown main groove. A plurality of first crown lug grooves extending to the main groove side and interrupting in the crown land portion, and a plurality of second crown lugs extending from the second crown main groove to the first crown main groove side and interrupting in the crown land portion. With a groove,
The crown vertical sipe is a tire extending from the first crown lug groove to the second crown lug groove .
Before Symbol crown land portion, the is partitioned by the crown longitudinal sipes and said plurality of first crown block is divided by the first crown lug groove, the crown longitudinal sipe and said plurality of second crown lug grooves 2. The tire according to claim 1, which includes a crown block.
The tire according to claim 2, wherein the first crown block and the second crown block are provided with a plurality of crown transverse groove pairs composed of two crown transverse grooves that completely cross the entire width of the block. The first crown block and the second crown block each have a plurality of small block pieces partitioned between the crown transverse groove pairs.
The small block piece has a length in the tire axial direction that is longer than that of the first small block piece or the first small block piece provided at the center of the second crown block in the tire circumferential direction. Including a large second small block piece
The tire according to claim 3, wherein the first small block piece formed on the first crown block is adjacent to the second small block piece formed on the second crown block via the crown vertical sipe. The crown vertical sipe has a first top portion that is convex toward the first crown main groove side and a second top portion that is convex toward the second crown main groove side.
The tire according to claim 3 or 4, wherein at least one of the crown lateral groove pairs communicates with both sides of the first top portion or the second top portion in the tire circumferential direction. The claim that at least one of the crown transverse grooves provided in the first crown block is smoothly continuous with the crown transverse grooves provided in the second crown block via the crown longitudinal sipe. The tire according to any one of 3 to 5. The tire according to any one of claims 3 to 6, wherein the minimum distance between the edges of the two crown lateral grooves is 2.0 to 5.0 mm. Claims 3 to 7 include the outer portion on the tread side and the inner portion provided inside the outer portion in the tire radial direction and extending with a constant width of less than 1.5 mm in the cross section. Tires listed in any of. The tire according to any one of claims 3 to 8, wherein the crown lateral narrow groove has a depth of 0.60 to 0.70 times that of the first crown main groove. The tire according to any one of claims 3 to 9, wherein the crown horizontal groove has the same depth as the crown vertical sipe. A tire with a tread
The tread portion includes a first crown main groove and a second crown main groove that extend continuously in the tire circumferential direction, and a crown land portion divided between the first crown main groove and the second crown main groove. And are provided,
The first crown main groove and the second crown main groove have a zigzag shape in which the phases are aligned with each other.
The land portion of the crown is provided with a vertical crown sipe that extends in a zigzag shape in the tire circumferential direction in a phase opposite to that of the first crown main groove and the second crown main groove.
The crown longitudinal bending angle of the sipes, the tire has smaller than bending angle of the crown main groove.

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