JP7499573B2 - Pneumatic tires - Google Patents

Description

This disclosure relates to pneumatic tires.

Conventionally, for example, a pneumatic tire includes a center main groove located in the center in the tire width direction, a plurality of inclined grooves extending from the center main groove toward the outside in the tire width direction and inclined with respect to the tire width direction, and a plurality of land portions defined by the center main groove and the plurality of inclined grooves (for example, Patent Document 1). The land portions include land grooves connecting the inclined grooves and a plurality of blocks defined by the land grooves and aligned in the tire width direction.

The multiple blocks include a center block that is located on the innermost side in the tire width direction, and the center block has multiple sipes. However, in the pneumatic tire of Patent Document 1, the multiple sipes extend in the tire width direction. As a result, in the center block, when traveling straight, the sipe pieces separated by the multiple sipes fall significantly in the tire circumferential direction, causing significant deformation of the center block.

JP 2016-578 A

Therefore, the objective of this disclosure is to provide a pneumatic tire that can suppress large deformation of the center block.

The pneumatic tire includes a center main groove extending in the tire circumferential direction and positioned in the center in the tire width direction, a plurality of inclined grooves extending from the center main groove toward the outside in the tire width direction and inclined with respect to the tire width direction, and a plurality of land portions defined by the center main groove and the plurality of inclined grooves, the land portions including land grooves connecting the inclined grooves and a plurality of blocks defined by the land grooves and aligned in the tire width direction, the plurality of blocks including a center block positioned on the innermost side in the tire width direction, the center block including a center sipe extending to divide the center block, the center sipe extending to intersect with the tire width direction and to intersect with the outer edge of the center block facing the inclined groove.

FIG. 1 is a development view of a main part of a tread surface of a pneumatic tire according to an embodiment; FIG. 1 is an explanatory diagram of a first inclined side FIG. 2 is an explanatory diagram of the second inclined side FIG. 1 is a development view of a main part of a tread surface of a pneumatic tire according to the embodiment; FIG. 1 is an enlarged view of a center block according to the embodiment; FIG. 1 is an enlarged view of a quarter block according to the embodiment; FIG. 1 is an enlarged view of a shoulder block according to the embodiment; Diagram of sipes

One embodiment of a pneumatic tire will be described below with reference to Figures 1 to 8. Note that in each figure, the dimensional ratios in the drawing do not necessarily match the actual dimensional ratios, and the dimensional ratios between the drawings do not necessarily match.

As shown in FIG. 1, the pneumatic tire (hereinafter simply referred to as "tire") 1 according to this embodiment includes a pair of bead portions (not shown), sidewall portions (not shown) extending radially outward from each bead portion, and a tread portion 2 connected to the radially outer ends of the pair of sidewall portions, the outer surface of which constitutes a tread surface 2a.

The tire 1 is mounted on a rim (not shown), and the inside of the tire 1 is pressurized with air. The use of the tire 1 is not particularly limited, but the tire 1 according to this embodiment is a so-called all-season tire that can be used on both snowy and dry roads.

In each figure, the first direction D1 is the tire width direction D1 that is parallel to the tire rotation axis, and the second direction D2 is the tire circumferential direction D2 that is a direction around the tire rotation axis. Note that the tire radial direction refers to the diameter direction of the tire 1.

The tire equatorial plane is a plane that is perpendicular to the tire rotation axis and is located at the center of the tire width direction D1, and the tire meridian plane is a plane that includes the tire rotation axis and is perpendicular to the tire equatorial plane. The tire equator L1 is a line on the tire equatorial plane that intersects with the tread surface 2a.

In the tire width direction D1, the inner side is the side closer to the tire equator L1, and the outer side is the side farther from the tire equator L1. In addition, one side D1a of the tire width direction D1 is called the first width direction side D1a, and the other side D1b is called the second width direction side D1b.

One side D2a of the tire circumferential direction D2 is called the first circumferential side D2a, and the other side D2b is called the second circumferential side D2b. Although not particularly limited, in this embodiment, the first circumferential side D2a is the rotation direction when the vehicle moves forward, that is, the rotation direction of the tire 1. As a result, in this embodiment, the first circumferential side D2a is the step-in side, and the second circumferential side D2b is the kick-out side.

As shown in FIG. 2, the side D3 that approaches the first circumferential side D2a as it approaches the first width direction side D1a (and the side that approaches the second circumferential side D2b as it approaches the second width direction side D1b) is called the first inclined side D3. As shown in FIG. 3, the side D4 that approaches the second circumferential side D2b as it approaches the first width direction side D1a (and the side that approaches the first circumferential side D2a as it approaches the second width direction side D1b) is called the second inclined side D4.

And, "having the same inclined side with respect to the tire width direction D1" means having the same inclined side (for example, first inclined sides D3, D3, or second inclined sides D4, D4). In other words, even if the inclination angle with respect to the tire width direction D1 is different, as long as it is the same inclined side D3, D3 (D4, D4), it is included in "having the same inclined side with respect to the tire width direction D1".

In addition, "opposite sides inclined with respect to the tire width direction D1" refers to opposite inclined sides (first inclined side D3 and second inclined side D4). In other words, even if the inclination angle with respect to the tire width direction D1 is the same, if the inclination sides D3 and D4 are opposite, it is included in "opposite sides inclined with respect to the tire width direction D1".

Returning to FIG. 1, the tread surface 2a has a contact surface that comes into contact with the road surface, and the outer ends of this contact surface in the tire width direction D1 are called contact ends 2b, 2b. Also, this contact surface refers to the tread surface 2a that comes into contact with the road surface when the tire 1 is mounted on a standard rim, inflated to the standard internal pressure, placed vertically on a flat road surface, and a standard load is applied.

A genuine rim is a rim that is determined for each tire 1 by the standard system that includes the standard on which the tire 1 is based. For example, in the case of JATMA, it is a standard rim, and in the cases of TRA and ETRTO, it is a "Measuring Rim."

The normal internal pressure is the air pressure set for each tire 1 by each standard in the standard system including the standard on which the tire 1 is based. For JATMA, it is the maximum air pressure, for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and for ETRTO, it is the "INFLATION PRESSURE". If the tire 1 is for a passenger car, it is 180 kPa, and if the tire 1 is a tire 1 described as Extra Load or Reinforced, it is 220 kPa.

The normal load is the load that each standard specifies for each tire 1 in the standard system that includes the standard on which tire 1 is based. For JATMA, it is the maximum load capacity, for TRA, it is the maximum value listed in the table above, and for ETRTO, it is the "LOAD CAPACITY." However, if tire 1 is for passenger cars, it is 88% of the load that corresponds to the internal pressure.

The tread portion 2 has a center main groove 3 arranged in the center of the tire width direction D1, and inclined grooves 4, 5 that extend from the center main groove 3 toward the outside in the tire width direction D1 and are inclined with respect to the tire width direction D1. Only one center main groove 3 is provided, and multiple inclined grooves 4, 5 are provided.

The center main groove 3 extends in the tire circumferential direction D2. Specifically, the center main groove 3 extends parallel to the tire circumferential direction D2. The center main groove 3 is disposed on the tire equator L1. The center main groove 3 may extend in a zigzag pattern along the tire circumferential direction D2.

The inclined grooves 4, 5 extend from the center main groove 3 to at least the ground contact end 2b. The multiple inclined grooves 4, 5 include a first inclined groove 4 extending from the center main groove 3 toward the first width direction side D1a, and a second inclined groove 5 extending from the center main groove 3 toward the second width direction side D1b.

The inclined grooves 4, 5 extend toward the second circumferential side D2b as they move outward in the tire width direction D1. Specifically, the first inclined groove 4 extends toward the second circumferential side D2b as it moves toward the outside of the tire width direction D1, i.e., toward the first width direction side D1a, and the second inclined groove 5 extends toward the second circumferential side D2b as it moves outward in the tire width direction D1, i.e., toward the second width direction side D1b.

As a result, the side D4 on which the first inclined groove 4 is inclined relative to the tire width direction D1 is opposite to the side D3 on which the second inclined groove 5 is inclined relative to the tire width direction D1. Specifically, the inclined side D4 of the first inclined groove 4 is the second inclined side D4, and the inclined side D3 of the second inclined groove 5 is the first inclined side D3. The first inclined grooves 4 and the second inclined grooves 5 are alternately arranged in the tire circumferential direction D2.

Although not particularly limited, the center main groove 3 and the inclined grooves 4, 5 may have a groove width of, for example, 3% or more of the distance between the ground contact ends 2b, 2b (dimension in the tire width direction D1). Although not particularly limited, the center main groove 3 and the inclined grooves 4, 5 may have a groove width of, for example, 5 mm or more.

The tread portion 2 also has a plurality of land portions 6 defined by the center main groove 3 and a plurality of inclined grooves 4, 4 (5, 5). The plurality of land portions 6 include a first land portion 6 defined by a pair of first inclined grooves 4, 4 adjacent to each other in the tire circumferential direction D2 and the center main groove 3, and a second land portion 6 defined by a pair of second inclined grooves 5, 5 adjacent to each other in the tire circumferential direction D2 and the center main groove 3.

The land portion 6 includes a land groove 7 that connects the inclined grooves 4, 4 (5, 5) and a plurality of blocks 8, 9, 10 that are partitioned by the land groove 7 and are arranged in the tire width direction D1. In this embodiment, each land portion 6 includes two land grooves 7 and three blocks 8, 9, 10.

The multiple blocks 8, 9, 10 are referred to as a center block 8, a quarter block 9, and a shoulder block 10 from the inside in the tire width direction D1. That is, the multiple blocks 8, 9, 10 include a center block 8 that is positioned on the innermost side in the tire width direction D1, a shoulder block 10 that is positioned on the outermost side in the tire width direction D1, and a quarter block 9 that is positioned between the center block 8 and the shoulder block 10.

In this embodiment, although not particularly limited, the side D3 (D4) on which the land groove 7 of the land portion 6 is inclined with respect to the tire width direction D1 is opposite to the side D4 (D3) on which the inclined groove 4 (5) is inclined with respect to the tire width direction D1. Specifically, the inclined side of the first inclined groove 4 is the second inclined side D4, while the inclined side of the land groove 7 of the first land portion 6 is the first inclined side D3, while the inclined side of the second inclined groove 5 is the first inclined side D3, while the inclined side of the land groove 7 of the second land portion 6 is the second inclined side D4.

As shown in FIG. 4, each block 8, 9, 10 has a first outer edge 8a, 9a, 10a arranged on the first circumferential side D2a and a second outer edge 8b, 9b, 10b arranged on the second circumferential side D2b. Each of the first outer edges 8a, 9a, 10a faces a common inclined groove 5, and each of the second outer edges 8b, 9b, 10b faces a common inclined groove 5.

The angle θ1 at which the first outer edge 8a of the center block 8 is inclined relative to the tire width direction D1 is greater than the angle θ2 at which the first outer edge 9a of the quarter block 9 is inclined relative to the tire width direction D1. The angle θ2 at which the first outer edge 9a of the quarter block 9 is inclined relative to the tire width direction D1 is greater than the angle θ3 at which the first outer edge 10a of the shoulder block 10 is inclined relative to the tire width direction D1.

The angle θ4 at which the second outer edge 8b of the center block 8 is inclined relative to the tire width direction D1 is greater than the angle θ5 at which the second outer edge 9b of the quarter block 9 is inclined relative to the tire width direction D1. The angle θ5 at which the second outer edge 9b of the quarter block 9 is inclined relative to the tire width direction D1 is greater than the angle θ6 at which the second outer edge 10b of the shoulder block 10 is inclined relative to the tire width direction D1.

Although not particularly limited, the angles θ1, θ4 at which the outer edges 8a, 8b of the center block 8 are inclined relative to the tire width direction D1 may be 40° to 60°. Also, although not particularly limited, the angles θ2, θ5 at which the outer edges 9a, 9b of the quarter block 9 are inclined relative to the tire width direction D1 may be 30° to 50°.

Although not particularly limited, the angles θ3 and θ6 at which the outer edges 10a and 10b of the shoulder block 10 are inclined relative to the tire width direction D1 may be 0° to 20°. Note that the angles θ1, θ2, θ3, θ4, θ5, and θ6 at which the outer edges 8a, 8b, 9a, 9b, 10a, and 10b of each block 8, 9, and 10 are inclined relative to the tire width direction D1 refer to the angles at which the inner ends of the outer edges 8a, 8b, 9a, 9b, 10a, and 10b in the tire width direction D1 are inclined relative to the tire width direction D1.

In this embodiment, the angles θ1, θ2, θ3, θ4, θ5, and θ6 at which the inclined grooves 4 and 5 are inclined relative to the tire width direction D1 become smaller toward the outside in the tire width direction D1. Note that the configuration of the inclined grooves 4 and 5 is not limited to this configuration.

The quarter block 9 also has a protruding portion 9c that protrudes toward the first circumferential side D2a with respect to the extension line L2 of the first outer edge 8a of the center block 8. The shoulder block 10 also has a protruding portion 10c that protrudes toward the first circumferential side D2a with respect to the extension line L3 of the first outer edge 9a of the quarter block 9.

As a result, the edges of the protrusions 9c and 10c facing the tire width direction D1 generate traction (a force that holds the tire in place without slipping) on a snowy road surface, for example. As a result, it is possible to improve cornering performance on a snowy road surface and improve skid prevention performance when traveling straight on a snowy road surface.

Each of the blocks 8, 9, and 10 has a number of sipes 11a, 11b, 12a, 12b, 13a, and 13b. The sipes 11a and 11b of the center block 8 are called center sipes 11a and 11b, the sipes 12a and 12b of the quarter block 9 are called quarter sipes 12a and 12b, and the sipes 13a and 13b of the shoulder block 10 are called shoulder sipes 13a and 13b.

The sipes 11a, 11b, 12a, 12b, 13a, and 13c are recesses having a width of 2.0 mm or less, and the land groove 7 is a recess having a width exceeding 2.0 mm. The land portion 6 may include not only the land groove 7 connecting the inclined grooves 4, 4 (5, 5) but also a land groove with at least one end separated from the inclined grooves 4, 5, i.e., a land groove disposed in the blocks 8, 9, and 10.

As shown in FIG. 5, the multiple center sipes 11a, 11b include straight sipes 11a that extend linearly and bent sipes 11b that have bends. The bent sipes 11b have straight portions at both ends and have multiple curved bends between the straight portions. Note that the bent sipes 11b may have multiple bends over their entire length, and the bends may be formed by bending a straight line, i.e., by bending.

The center sipes 11a and 11b extend so as to divide the center block 8. The number of center sipes 11a and 11b is not particularly limited, but in this embodiment, there are five, and therefore the center block 8 has six block pieces 8c divided by the center sipes 11a and 11b.

The length W2 of the center block 8 in the tire circumferential direction D2 is longer than the length W1 of the center block 8 in the tire width direction D1. Furthermore, because each end of the center block 8 in the tire circumferential direction D2 forms an acute angle, the rigidity of the ends of the center block 8 in the tire circumferential direction D2 is low.

Therefore, straight sipes 11a with short sipe lengths are arranged at each end of the center block 8 in the tire circumferential direction D2. This makes it possible to prevent the rigidity of the end of the center block 8 in the tire circumferential direction D2 from becoming too low.

Moreover, the bent sipes 11b, which have a long sipe length, are arranged between the straight sipes 11a, 11a in the tire circumferential direction D2, i.e., in the center of the center block 8 in the tire circumferential direction D2. This ensures the edge length of the center sipes 11a, 11b. Therefore, the edge length of the center sipes 11a, 11b can be ensured while preventing the rigidity of the center block 8 from becoming too low.

Although not particularly limited, the depth of the straight sipes 11a is shallower than the depth of the curved sipes 11b. This effectively prevents the rigidity of the end of the center block 8 in the tire circumferential direction D2 from becoming too low.

However, when traveling straight (driving), the center sipes 11a, 11b are likely to receive a force F1 in the tire circumferential direction D2 (especially the second circumferential side D2b, which is opposite to the direction of rotation). Therefore, the center sipes 11a, 11b extend so as to intersect with the tire width direction D1. This makes it possible to prevent the block piece 8c of the center block 8 from falling in the tire circumferential direction D2 when traveling straight.

As a result, the deformation of the center block 8 can be prevented from becoming too large when traveling straight, improving tire performance when traveling straight on snowy roads and when traveling straight on dry roads. Although not particularly limited, the angle θ7 (≦90°) at which the center sipes 11a, 11b intersect with the tire width direction D1 is preferably 5° or more, more preferably 10° or more, and even more preferably 15° or more.

In addition, when driving and braking, the center block 8 is likely to receive a force F2 in a direction perpendicular to the outer edges 8a and 8b (particularly the first outer edge 8a on the leading side). Therefore, the center sipes 11a and 11b extend so as to intersect with the outer edges 8a and 8b. This makes it possible to prevent the block pieces 8c of the center block 8 from falling in a direction perpendicular to the outer edges 8a and 8b when driving and braking.

Therefore, the deformation of the center block 8 during driving and braking can be suppressed, improving tire performance during driving and braking on snowy roads and tire performance during driving and braking on dry roads. Although not particularly limited, the angles θ8, θ9 (≦90°) at which the center sipes 11a, 11b intersect with the outer edges 8a, 8b are preferably 50° or more, more preferably 60° or more, and even more preferably 70° or more.

Moreover, the side D4 on which the center sipes 11a, 11b are inclined relative to the tire width direction D1 is opposite to the side D3 on which the inclined groove 5 is inclined relative to the tire width direction D1. Specifically, the inclined side of the center sipes 11a, 11b of the second land portion 6 is the second inclined side D4, and the inclined side of the second inclined groove 5 is the first inclined side D3.

This prevents the angles θ8, θ9 at which the center sipes 11a, 11b intersect with the outer edges 8a, 8b from becoming too small, and therefore prevents the rigidity of the acute corners of the block pieces 8c from becoming too low. Therefore, for example, it is possible to effectively prevent the block pieces 8c from falling over, and it is possible to prevent uneven wear of the block pieces 8c due to the difference in rigidity between the corners and the center.

As shown in FIG. 6, the multiple quarter sipes 12a, 12b include straight sipes 12a that extend linearly and bent sipes 12b that have bends. Although not particularly limited, in this embodiment, the bent sipes 12b have straight portions at both ends and multiple bends between the straight portions.

In this embodiment, the quarter sipes 12a and 12b extend so as to divide the quarter block 9, although this is not particularly limited. The number of quarter sipes 12a and 12b is seven in this embodiment, although this is not particularly limited. As a result, the quarter block 9 has eight block pieces 9d that are divided by the quarter sipes 12a and 12b.

The length W4 of the quarter block 9 in the tire circumferential direction D2 is longer than the length W3 of the quarter block 9 in the tire width direction D1. Furthermore, the ends of the quarter block 9 in the tire circumferential direction D2 form acute corners. In contrast, the straight sipes 12a with short sipe length are arranged at each end of the quarter block 9 in the tire circumferential direction D2, and the bent sipes 12b with long sipe length are arranged between the straight sipes 12a, 12a in the tire circumferential direction D2.

This makes it possible to ensure the edge length of the quarter sipes 12a and 12b while preventing the rigidity of the quarter block 9 from decreasing. Although not particularly limited, in this embodiment, the depth of the straight sipe 12a is shallower than the depth of the bent sipe 12b.

The quarter sipes 12a, 12b also extend so as to intersect with the tire width direction D1. This makes it possible to suppress significant deformation of the quarter block 9 even when the quarter sipes 12a, 12b are subjected to a force F3 in the tire circumferential direction D2. Although not particularly limited, the angle θ10 (≦90°) at which the quarter sipes 12a, 12b intersect with the tire width direction D1 is preferably 10° or more, more preferably 20° or more, and even more preferably 30° or more.

When driving straight, the contact length (the length in the tire circumferential direction D2 that is in contact with the road surface) is the longest at the center block 8, while when cornering, a larger force acts on the outer side in the tire width direction D1. On the other hand, the angle θ7 at which the center sipes 11a, 11b intersect with the tire width direction D1 is smaller than the angle θ10 at which the quarter sipes 12a, 12b intersect with the tire width direction D1.

As a result, the angle θ7 at which the center sipes 11a, 11b intersect with the tire width direction D1 is small, so the edge effect of the center sipes 11a, 11b is large when traveling straight. And because the contact length of the center block 8 is long when traveling straight, the total edge length of the center sipes 11a, 11b that come into contact with the ground when traveling straight is long. Therefore, the edge effect when traveling straight can be improved.

In addition, because the angle θ10 at which the quarter sipes 12a, 12b intersect with the tire width direction D1 is large, the edge effect of the quarter sipes 12a, 12b is large when cornering. And because the quarter sipes 12a, 12b are located further outboard in the tire width direction D1 than the center sipes 11a, 11b when cornering, the edge effect when cornering can be improved.

The quarter sipes 12a, 12b extend so as to intersect with the outer edges 9a, 9b. This makes it possible to prevent the deformation of the quarter block 9 from becoming too large even when the quarter block 9 receives a force F4 in a direction perpendicular to the outer edges 9a, 9b. Although not particularly limited, the angles θ11, θ12 (≦90°) at which the quarter sipes 12a, 12b intersect with the outer edges 9a, 9b are preferably 50° or more, more preferably 60° or more, and even more preferably 70° or more.

The side D4 on which the quarter sipes 12a, 12b are inclined relative to the tire width direction D1 is opposite to the side D3 on which the inclined groove 5 is inclined relative to the tire width direction D1. Specifically, the inclined side of the quarter sipes 12a, 12b of the second land portion 6 is the second inclined side D4, and the inclined side of the second inclined groove 5 is the first inclined side D3.

As shown in FIG. 7, the multiple shoulder sipes 13a, 13b include straight sipes 13a that extend linearly and bent sipes 13b that have bends. Although not particularly limited, in this embodiment, the bent sipes 13b have straight portions at both ends and multiple bends between the straight portions.

In this embodiment, the shoulder sipes 13a, 13b extend from the land groove 7 to the ground contact end 2b so as to divide the shoulder block 10, although this is not particularly limited. The number of shoulder sipes 13a, 13b is not particularly limited, but in this embodiment, it is three, so that the shoulder block 10 has four block pieces 10d divided by the shoulder sipes 13a, 13b.

The length W5 of the shoulder block 10 in the tire width direction D1 is longer than the length W6 of the shoulder block 10 in the tire circumferential direction D2. The curved sipes 13b are arranged at each end of the shoulder block 10 in the tire circumferential direction D2, and the straight sipes 13a are arranged between the curved sipes 13b, 13b in the tire circumferential direction D2.

The angle θ13 at which the shoulder sipes 13a, 13b intersect with the tire width direction D1 is smaller than the angle θ10 at which the quarter sipes 12a, 12b intersect with the tire width direction D1. Although not particularly limited, the angle θ13 (≦90°) at which the shoulder sipes 13a, 13b intersect with the tire width direction D1 is preferably 0° to 20°.

As a result, the angle θ13 at which the shoulder sipes 13a, 13b intersect with the tire width direction D1 is small, so the edge effect of the shoulder sipes 13a, 13b is large during braking. And because the contact length of the shoulder block 10 is long during braking, the total edge length of the shoulder sipes 13a, 13b that come into contact with the ground during braking is long. Therefore, the edge effect during braking can be improved.

Here, the "direction in which the sipes extend," "the angle at which the sipes intersect," and "the side to which the sipes are inclined" will be explained with reference to Figure 8. Note that Figure 8 illustrates center sipes 11a and 11b, but the same is true for quarter sipes 12a and 12b and shoulder sipes 13a and 13b.

As shown in FIG. 8, the extension direction of the sipes 11a and 11b is the extension direction of the straight line L4 (shown by a dashed line in FIG. 8) connecting both ends 11c and 11c of the sipes 11a and 11b. For example, the extension direction of the bottom sipe 11a in FIG. 8, i.e., the gently curved straight sipe 11a, is also the extension direction of the straight line L4 connecting both ends 11c and 11c of the straight sipe 11a.

For example, the direction in which the middle sipe 11b in FIG. 8, i.e., the bent sipe 11b having straight portions on both sides, extends is the direction of the straight line L4d connecting both ends 11c, 11c of the bent sipe 11b. For example, the direction in which the top sipe 11b in FIG. 8, i.e., the bent sipe 11b having multiple bends over its entire length, extends is the direction of the straight line L4 connecting both ends 11c, 11c of the bent sipe 11b.

The "angle at which the sipes intersect" and the "side to which the sipes are inclined" are based on the "direction in which the sipes extend." For example, the angle θ7 at which the sipes 11a and 11b intersect with the tire width direction D1 is the angle at which the extension direction of the sipes 11a and 11b intersect with the tire width direction D1.

Also, for example, the angles θ8, θ9 at which the sipes 11a, 11b intersect with the outer edges 8a, 8b are the angles at which the extension direction of the sipes 11a, 11b intersects with the outer edges 8a, 8b at the position of the end 11c of the sipes 11a, 11b (in the case of a curve, the tangent to the outer edges 8a, 8b at the position of the end 11c). Also, for example, the side D4 on which the sipes 11a, 11b are inclined with respect to the tire width direction D1 is the side D4 on which the extension direction of the sipes 11a, 11b is inclined with respect to the tire width direction D1.

As described above, the pneumatic tire 1 according to this embodiment includes a center main groove 3 extending in the tire circumferential direction D2 and disposed in the center of the tire width direction D1, a plurality of inclined grooves 4, 5 extending from the center main groove 3 toward the outside of the tire width direction D1 and inclined with respect to the tire width direction D1, and a plurality of land portions 6 defined by the center main groove 3 and the plurality of inclined grooves 4, 4 (5, 5). The land portions 6 include a land groove 7 connecting the inclined grooves 4, 4 (5, 5) with each other, and a land groove 7 defined by the land groove 7. The plurality of blocks 8, 9, 10 are arranged in the tire width direction D1, and the plurality of blocks 8, 9, 10 include a center block 8 that is arranged on the inner side of the tire width direction D1, and the center block 8 has center sipes 11a, 11b that extend to divide the center block 8, and the center sipes 11a, 11b extend to intersect with the tire width direction D1 and the outer edges 8a, 8b of the center block 8 that face the inclined grooves 4, 5.

With this configuration, the center sipes 11a, 11b are susceptible to a force F1 in the tire circumferential direction D2 when traveling straight, but the center sipes 11a, 11b extend so as to intersect with the tire width direction D1. This makes it possible to prevent the block pieces 8c separated by the center sipes 11a, 11b from falling in the tire circumferential direction D2 when traveling straight.

In addition, while driving and braking, the center block 8 is likely to receive a force F2 in a direction perpendicular to the outer edges 8a, 8b facing the inclined grooves 4, 5. Therefore, the center sipes 11a, 11b extend so as to intersect with the outer edges 8a, 8b of the center block 8 facing the inclined grooves 4, 5. This makes it possible to prevent the block pieces 8c of the center block 8 from falling in a direction perpendicular to the outer edges 8a, 8b. Therefore, it is possible to prevent the deformation of the center block 8 from becoming too large.

In addition, in the pneumatic tire 1 according to this embodiment, the center sipes 11a, 11b are provided in plurality, and the plurality of center sipes 11a, 11b include straight sipes 11a extending linearly and bent sipes 11b having a bend, the length W2 of the center block 8 in the tire circumferential direction D2 is longer than the length W1 of the center block 8 in the tire width direction D1, the straight sipes 11a are arranged at each end of the center block 8 in the tire circumferential direction D2, and the bent sipes 11b are arranged between the straight sipes 11a, 11a in the tire circumferential direction D2.

With this configuration, the length W2 of the center block 8 in the tire circumferential direction D2 is longer than the length W1 of the center block 8 in the tire width direction D1. This reduces the rigidity of the end of the center block 8 in the tire circumferential direction D2.

In contrast, the straight sipes 11a, which have a short sipe length, are arranged at each end of the center block 8 in the tire circumferential direction D2, so that the rigidity of the end of the center block 8 in the tire circumferential direction D2 can be prevented from becoming too low. Furthermore, the bent sipes 11b, which have a long sipe length, are arranged between the straight sipes 11a, 11a, so that the edge length of the center sipes 11a, 11b can be secured.

In the pneumatic tire 1 according to this embodiment, the land portion 6 includes two land grooves 7, 7 connecting the inclined grooves 4, 4 (5, 5) and three blocks 8, 9, 10 that are partitioned by the two land grooves 7, 7 and are arranged in the tire width direction D1. The multiple blocks 8, 9, 10 include a shoulder block 10 that is arranged on the outermost side of the tire width direction D1 and a quarter block 9 that is arranged between the center block 8 and the shoulder block 10. The quarter block 9 includes quarter sipes 12a, 12b, and the angle θ7 at which the center sipes 11a, 11b intersect with the tire width direction D1 is smaller than the angle θ10 at which the quarter sipes 12a, 12b intersect with the tire width direction D1.

With this configuration, the angle θ7 at which the center sipes 11a, 11b intersect with the tire width direction D1 is small, so the edge effect of the center sipes 11a, 11b is large when driving straight. Also, the angle θ10 at which the quarter sipes 12a, 12b intersect with the tire width direction D1 is large, so the edge effect of the quarter sipes 12a, 12b is large when turning. Therefore, the edge effect can be improved when driving straight and when turning.

In the pneumatic tire 1 according to this embodiment, the land portion 6 includes two land grooves 7, 7 connecting the inclined grooves 4, 4 (5, 5) and three blocks 8, 9, 10 that are partitioned by the two land grooves 7, 7 and are arranged in the tire width direction D1. The multiple blocks 8, 9, 10 include a shoulder block 10 that is arranged on the outermost side of the tire width direction D1 and a quarter block 9 that is arranged between the center block 8 and the shoulder block 10. The shoulder block 10 includes shoulder sipes 13a, 13b, and the quarter block 9 includes quarter sipes 12a, 12b. The angle θ13 at which the shoulder sipes 13a, 13b intersect with the tire width direction D1 is smaller than the angle θ10 at which the quarter sipes 12a, 12b intersect with the tire width direction D1.

With this configuration, the angle θ13 at which the shoulder sipes 13a, 13b intersect with the tire width direction D1 is small, so the edge effect of the shoulder sipes 13a, 13b is large during braking. Also, the angle θ10 at which the quarter sipes 12a, 12b intersect with the tire width direction D1 is large, so the edge effect of the quarter sipes 12a, 12b is large during cornering. Therefore, the edge effect during braking and cornering can be improved.

In addition, in the pneumatic tire 1 according to this embodiment, the side D4 (D3) on which the center sipes 11a, 11b are inclined relative to the tire width direction D1 is opposite the side D3 (D4) on which the inclined grooves 5 (4) are inclined relative to the tire width direction D1.

With this configuration, the side D4 (D3) on which the center sipes 11a, 11b are inclined relative to the tire width direction D1 is opposite the side D3 (D4) on which the inclined grooves 5 (4) are inclined relative to the tire width direction D1, so that the angles θ8, θ9 at which the center sipes 11a, 11b intersect with the outer edges 8a, 8b can be prevented from becoming too small. This can prevent the rigidity of the block pieces 8c of the center block 8 from decreasing too much.

The pneumatic tire 1 is not limited to the configuration of the embodiment described above, nor is it limited to the above-mentioned effects. Furthermore, the pneumatic tire 1 can of course be modified in various ways without departing from the spirit of the present invention. For example, it is of course possible to arbitrarily select one or more of the configurations, methods, etc. related to the various modified examples described below and adopt them in the configurations, methods, etc. related to the embodiment described above.

(1) In the pneumatic tire 1 according to the above embodiment, the land portion 6 is configured to have two land grooves 7, 7 that connect the inclined grooves 4, 4 (5, 5) to each other. However, the pneumatic tire 1 is not limited to such a configuration. For example, the land portion 6 may be configured to have one or three or more land grooves 7, 7 that connect the inclined grooves 4, 4 (5, 5) to each other, and thus may be configured to have two or four or more blocks 8, 9, 10.

(2) In addition, in the pneumatic tire 1 according to the above embodiment, the center block 8 is configured to have multiple center sipes 11a, 11b. However, the pneumatic tire 1 is not limited to such a configuration. For example, the center block 8 may be configured to have one center sipe 11a (11b).

(3) In addition, in the pneumatic tire 1 according to the above embodiment, the quarter block 9 is configured to have multiple quarter sipes 12a, 12b. However, the pneumatic tire 1 is not limited to such a configuration. For example, the quarter block 9 may be configured to have one quarter sipe 12a (12b), or may be configured to have no quarter sipe 12a (12b).

(4) In addition, in the pneumatic tire 1 according to the above embodiment, the shoulder block 10 is configured to have multiple shoulder sipes 13a, 13b. However, the pneumatic tire 1 is not limited to such a configuration. For example, the shoulder block 10 may be configured to have one shoulder sipe 13a (13b), or may be configured to have no shoulder sipe 13a (13b).

(5) In addition, in the pneumatic tire 1 according to the above embodiment, each block 8, 9, 10 is configured to have straight sipes 11a, 12a, 13a and curved sipes 11b, 12b, 13b. However, the pneumatic tire 1 is not limited to such a configuration. For example, at least one of the multiple blocks 8, 9, 10 may be configured to have only one of the straight sipes 11a, 12a, 13a or the curved sipes 11b, 12b, 13b.

(6) In addition, in the pneumatic tire 1 according to the above embodiment, the straight sipes 11a of the center block 8 are arranged at each end of the center block 8 in the tire circumferential direction D2. However, the pneumatic tire 1 is not limited to this configuration. For example, the curved sipes 11b of the center block 8 may be arranged at least at one end of the center block 8 in the tire circumferential direction D2.

(7) In addition, in the pneumatic tire 1 according to the above embodiment, the straight sipes 12a of the quarter block 9 are arranged at each end of the quarter block 9 in the tire circumferential direction D2. However, the pneumatic tire 1 is not limited to such a configuration. For example, the curved sipes 12b of the quarter block 9 may be arranged at least at one end of the quarter block 9 in the tire circumferential direction D2.

(8) In addition, in the pneumatic tire 1 according to the above embodiment, the angle θ7 at which the center sipes 11a, 11b intersect with the tire width direction D1 is smaller than the angle θ10 at which the quarter sipes 12a, 12b intersect with the tire width direction D1. However, the pneumatic tire 1 is not limited to such a configuration. For example, the angle θ7 of the center sipes 11a, 11b may be larger than the angle θ10 of the quarter sipes 12a, 12b.

(9) In addition, in the pneumatic tire 1 according to the above embodiment, the angle θ13 at which the shoulder sipes 13a, 13b intersect with the tire width direction D1 is smaller than the angle θ10 at which the quarter sipes 12a, 12b intersect with the tire width direction D1. However, the pneumatic tire 1 is not limited to such a configuration. For example, the angle θ13 of the shoulder sipes 13a, 13b may be larger than the angle θ10 of the quarter sipes 12a, 12b.

(10) In addition, in the pneumatic tire 1 according to the above embodiment, the side D4 (D3) on which the center sipes 11a, 11b are inclined relative to the tire width direction D1 is opposite the side D3 (D4) on which the inclined groove 5 (4) is inclined relative to the tire width direction D1. However, the pneumatic tire 1 is not limited to such a configuration. For example, the inclined side of the center sipes 11a, 11b may be the same as the inclined side of the inclined groove 5 (4).

(11) In addition, in the pneumatic tire 1 according to the above embodiment, the side D4 (D3) on which the quarter sipes 12a, 12b are inclined relative to the tire width direction D1 is opposite the side D3 (D4) on which the inclined groove 5 (4) is inclined relative to the tire width direction D1. However, the pneumatic tire 1 is not limited to such a configuration. For example, the inclined side of the quarter sipes 12a, 12b may be the same as the inclined side of the inclined groove 5 (4).

1...pneumatic tire, 2...tread portion, 2a...tread surface, 2b...ground edge, 3...center main groove, 4...first inclined groove, 5...second inclined groove, 6...land portion, 7...land groove, 8...center block, 8a...first outer edge, 8b...second outer edge, 8c...block piece, 9...quarter block, 9a...first outer edge, 9b...second outer edge, 9c...projection, 9d...block piece, 10...shoulder block, 10a...first outer edge, 10b...second outer edge, 10c...projection, 10d...block Lock piece, 11a...center sipe (straight sipe), 11b...center sipe (bent sipe), 11c...end, 12a...quarter sipe, 12b...quarter sipe, 13a...shoulder sipe, 13b...shoulder sipe, D1...tire width direction, D1a...first width direction side, D1b...second width direction side, D2...tire circumferential direction, D2a...first circumferential side, D2b...second circumferential side, D3...first inclined side, D4...second inclined side, L1...tire equator

Claims (5)

A center main groove extending in a tire circumferential direction and disposed in a center in a tire width direction;
A plurality of inclined grooves extending from the center main groove toward an outer side in the tire width direction and inclined with respect to the tire width direction;
a plurality of land portions defined by the center main groove and a plurality of inclined grooves;
The land portion includes a land groove connecting the inclined grooves and a plurality of blocks partitioned by the land groove and arranged in the tire width direction,
The plurality of blocks includes a center block disposed on the innermost side in the tire width direction,
The center block includes a center sipe extending to divide the center block,
The center sipe extends so as to intersect with the tire width direction and with an outer edge of the center block facing the inclined groove,
The center sipe is provided in plurality,
The plurality of center sipes include linear sipes extending linearly and bent sipes having a bend,
A pneumatic tire, wherein a depth of the straight sipes is shallower than a depth of the curved sipes. The center sipe is provided in plurality,
The plurality of center sipes include linear sipes extending linearly and bent sipes having a bend,
The length of the center block in the tire circumferential direction is longer than the length of the center block in the tire width direction,
The linear sipes are disposed at each end of the center block in the tire circumferential direction,
The pneumatic tire according to claim 1 , wherein the curved sipes are arranged between the straight sipes in the tire circumferential direction. The land portion includes two land grooves connecting the inclined grooves to each other, and three blocks partitioned by the two land grooves and aligned in the tire width direction,
The plurality of blocks include a shoulder block disposed outermost in the tire width direction, and a quarter block disposed between the center block and the shoulder block,
The quarter block includes a quarter sipe.
The pneumatic tire according to claim 1 , wherein an angle at which the center sipe intersects with the tire width direction is smaller than an angle at which the quarter sipe intersects with the tire width direction. The land portion includes two land grooves connecting the inclined grooves to each other, and three blocks partitioned by the two land grooves and arranged in the tire width direction,
The plurality of blocks include a shoulder block disposed outermost in the tire width direction and a quarter block disposed between the center block and the shoulder block,
The shoulder block includes a shoulder sipe.
The quarter block includes a quarter sipe.
The pneumatic tire according to claim 1 , wherein an angle at which the shoulder sipes intersect with the tire width direction is smaller than an angle at which the quarter sipes intersect with the tire width direction. The pneumatic tire according to claim 1 , wherein a side on which the center sipe is inclined with respect to the tire width direction is opposite a side on which the inclined groove is inclined with respect to the tire width direction.

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