JP7650690B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire.

For example, as described in Patent Document 1, a pneumatic tire is known in which the tread is divided into an axially central region and two shoulder lands adjacent to each other by shoulder main grooves extending in the tire circumferential direction, and the axially central region is further divided into multiple lands by other main grooves. A pneumatic tire is also known in which axially extending slits and sipes are provided alternately in the tire circumferential direction on each land in the axially central region of such a pneumatic tire, as described in Patent Document 1.

This type of pneumatic tire has excellent traction due to the effect of the slits and sipes that extend in the tire axial direction. Also, not all of the grooves that extend in the tire axial direction are slits, but slits and sipes that are narrower than the slits are arranged alternately in the tire circumferential direction, so that when the land deforms, the sipes close and the rigidity of the land is ensured.

JP 2015-116845 A

However, it is difficult to achieve a good balance between traction and rigidity on land in pneumatic tires like the ones described above. For example, the deeper the slits, the better the traction, but the lower the rigidity on land.

Therefore, the objective of the present invention is to provide a pneumatic tire that has an excellent balance between traction and rigidity on land.

In the pneumatic tire of the embodiment, the tread is divided into a plurality of lands extending in the tire circumferential direction by a plurality of main grooves extending in the tire circumferential direction, and the main grooves include shoulder main grooves that divide the tread into an axially central region of the tire and shoulder lands on both sides of the central region of the tire, and a plurality of main grooves that divide the central region of the tire into a plurality of lands. Each land in the axially central region of the tire is provided with slits and sipes that extend in the tire axial direction and divide the land. In the pneumatic tire in which the slits and the sipes are alternately provided in the tire circumferential direction, a slit bottom sipe that is a sipe different from the sipes is provided at the bottom of the slit, the depth of the slit is 10 to 40% of the depth of the main groove, the depth of the groove including the slit and the slit bottom sipe is 60 to 90% of the depth of the main groove, and the slits and the sipes are aligned on a line on both sides of the tire equator and extend in a direction that forms a V shape when viewed with the side that first touches the ground during forward rotation facing down .

The pneumatic tire of this embodiment has an excellent balance between traction and rigidity on land due to the above-mentioned characteristics of the slits and sipes.

2 shows a tread pattern of a pneumatic tire according to an embodiment. 2 is a cross-sectional view taken along line AA in FIG. 1 . FIG. 2 is an enlarged view of part B in FIG. 3C-C cross-sectional view of FIG.

The embodiment will be described with reference to the drawings. Note that the embodiment described below is merely an example, and any modifications that do not deviate from the spirit of the present invention are considered to be within the scope of the present invention.

The pneumatic tire of the embodiment has a typical cross-sectional structure of a pneumatic tire, except for the tread. Specifically, bead portions (bead portions are portions including a bead core and a bead filler) are provided on both sides in the axial direction of the tire, and a carcass ply is provided from one bead portion to the other bead portion in the axial direction of the tire. A belt is provided on the outer diameter side of the carcass ply, and a tread is provided on the outer diameter side of the belt. An inner liner is provided on the inside of the carcass ply, and sidewall rubber is provided on both sides of the carcass ply in the axial direction of the tire. In addition to the above, a number of rubber members are provided to configure the pneumatic tire.

As shown in FIG. 1, shoulder main grooves 25 extending in the tire circumferential direction are provided on both axial sides of the tread. The shoulder main grooves 25 divide the tread into an axially central region 22 where the tire equator C is located, and shoulder lands 21 on both axially opposite sides of the central region 22.

The axially central region 22 of the tire is provided with a center main groove 26 that overlaps with the tire equator C and extends in the tire circumferential direction, and a quarter main groove 27 that extends in the tire circumferential direction between the center main groove 26 and the shoulder main groove 25.

The center main groove 26, quarter main groove 27, and shoulder main groove 25 are zigzag main grooves. The axial deviation of the zigzag groove is greatest for the center main groove 26, quarter main groove 27, and shoulder main groove 25 in that order. Conversely, the shoulder main groove 25 is closest to being straight, followed by the quarter main groove 27 and center main groove 26 in that order.

The center main groove 26 and quarter main grooves 27 in the axially central region 22 of the tire are narrower than the shoulder main grooves 25. Specifically, the width of the center main groove 26 and quarter main groove 27 is 30 to 70% of the width of the shoulder main groove 25.

The axially central region 22 of the tire is divided into a center main groove 26 and a quarter main groove 27, so that four lands extending in the circumferential direction of the tire are formed in the axially central region 22 of the tire. The four lands are a center land 23 between the center main groove 26 and the quarter main groove 27, and a quarter land 24 between the quarter main groove 27 and the shoulder main groove 25.

As described above, each of the main grooves 25, 26, 27 is zigzag-shaped, so that the center land 23, the quarter land 24, and the shoulder land 21 have wide sections 23a, 24a, 21a and narrow sections 23b, 24b, 21b.

Looking at the center land 23, in the wide portion 23a, the main grooves on both sides of the center land 23 (center main groove 26 and quarter main groove 27) are bent in a direction that widens the width of the center land 23, and in the narrow portion 23b, the main grooves on both sides of the center land 23 are bent in a direction that narrows the width of the center land 23.

Looking at the quarter land 24, in the wide portion 24a, the main grooves on both sides of the quarter land 24 (quarter main groove 27 and shoulder main groove 25) are bent in a direction that widens the width of the quarter land 24, and in the narrow portion 24b, the main grooves on both sides of the quarter land 24 are bent in a direction that narrows the width of the quarter land 24.

Looking at the shoulder land 21, in the wide portion 21a, the shoulder main groove 25 is bent in a direction that widens the width of the shoulder land 21, and in the narrow portion 21b, the shoulder main groove 25 is bent in a direction that narrows the width of the shoulder land 21.

In each land 23, 24 of the tire axial center region 22, slits 30 and sipes 31, which are a type of groove, are alternately provided in the tire circumferential direction. That is, in each of the two center lands 23, slits 30 and sipes 31 are alternately provided in the tire circumferential direction, and in each of the two quarter lands 24, slits 30 and sipes 31 are alternately provided in the tire circumferential direction. As a result, multiple blocks are formed in each of the center lands 23 and quarter lands 24. Here, the slits 30 and sipes 31 are grooves that extend in the tire axial direction and divide the lands. The slits 30 are grooves with a width greater than 1.5 mm. The sipes 31 are grooves with a width of 1.5 mm or less.

In the center land 23, the slit 30 is provided in the narrow portion 23b and connects the bent portion of the center main groove 26 to the bent portion of the quarter main groove 27. In addition, in the center land 23, the sipe 31 is provided in the wide portion 23a and connects the bent portion of the center main groove 26 to the bent portion of the quarter main groove 27.

Also, in the quarter land 24, the slit 30 is provided in the narrow portion 24b, connecting the bent portion of the center main groove 26 and the bent portion of the quarter main groove 27. Also, in the quarter land 24, the sipe 31 is provided in the wide portion 24a, connecting the bent portion of the center main groove 26 and the bent portion of the quarter main groove 27.

In the center land 23 and quarter land 24, the depth of the slit 30 is 10 to 40% of the depth of the center main groove 26 and quarter main groove 27. Also, as shown in FIG. 2, in the center land 23 and quarter land 24, a slit bottom sipe 32 having a width of 1.5 mm or less is provided at the groove bottom of the slit 30. Also, in the center land 23 and quarter land 24, the combined depth of the slit 30 and the slit bottom sipe 32 is 60 to 90% of the depth of the center main groove 26 and quarter main groove 27.

As shown in FIG. 1, the slits 30 and sipes 31 in the axially central region 22 of the tire are arranged alternately in the axial direction of the tire, and are aligned on a single line. For example, next to the slit 30 in the quarter land 24 on one side of the axial direction of the tire is the sipe 31 in the center land 23 on one side of the axial direction of the tire, next to the sipe 31 is the slit 30 in the center land 23 on the other side of the axial direction of the tire, and next to the sipe 31 is the sipe 31 in the quarter land 24 on the other side of the axial direction of the tire. These slits 30, sipes 31, slits 30 and sipes 31 are aligned on a single line.

The slits 30 and sipes 31 arranged on a line in this way extend in a direction inclined to the tire axial direction so as to be line-symmetrical with respect to the tire equator C. That is, the slits 30 and sipes 31 on one side of the tire axial direction are arranged on a line inclined to the tire axial direction, and the slits 30 and sipes 31 on the other side of the tire axial direction are also arranged on a line inclined to the tire axial direction. The lines on one side and the other side of the tire axial direction are connected at the tire equator C and are line-symmetrical with respect to the tire equator C. In FIG. 1, the bottom is the side that touches the ground first when the tire is rotating forward (when the tire rolls to move the vehicle forward), and as shown in this figure, the line consisting of the slits 30 and sipes 31 is V-shaped.

Notches 28, 29 are formed at the ends of the sipes 31 that face the slits 30 across the main grooves 25, 26, 27. In more detail, where the sipes 31 of the center land 23 open into the center main groove 26 and the quarter main groove 27, a notch 28 is formed that is a triangular cutout of the center land 23. This notch 28 partially widens the width of the sipes 31.

In addition, where the sipes 31 of the quarter land 24 open into the quarter main groove 27 and the shoulder main groove 25, triangular notches 29 are formed in the quarter land 24. The notches 29 partially widen the width of the sipes 31.

In addition, slits 33 and sipes 34 are provided alternately in the circumferential direction of the tire on the shoulder land 21. The slits 33 are grooves with a width greater than 1.5 mm. The sipes 34 are grooves with a width of 1.5 mm or less.

The slits 33 and sipes 34 on the shoulder land 21 are bent and extend in a V-shape when viewed with the side that touches the ground first when the tire is rotating forward facing downwards.

One end of the slit 33 in the shoulder land 21 (the end on the tire equator C side) opens into the shoulder main groove 25, and the other end is located beyond the tire ground contact edge E. Therefore, the slits 33 divide the shoulder land 21 into multiple blocks. The slits 33 in the shoulder land 21 do not have sipes at the bottom of the slits.

In addition, one end of the sipe 34 of the shoulder land 21 (the end on the tire equator C side) opens into the shoulder main groove 25, but the other end is closed at a position closer to the tire equator C than the tire ground contact edge E. In other words, the other end of the sipe 34 is closed within the shoulder land 21.

In the shoulder land 21, the slit 33 is provided in the narrow portion 21b and opens into the bend of the shoulder main groove 25. In addition, in the shoulder land 21, the sipe 34 is provided in the wide portion 21a and opens into the bend of the shoulder main groove 25.

The opening end of the slit 33 of the shoulder land 21 facing the shoulder main groove 25 faces the opening end of the sipe 31 of the quarter land 24 facing the shoulder main groove 25 across the shoulder main groove 25. Also, the opening end of the sipe 34 of the shoulder land 21 facing the shoulder main groove 25 faces the opening end of the slit 30 of the quarter land 24 facing the shoulder main groove 25 across the shoulder main groove 25.

Where the sipe 34 of the shoulder land 21 opens into the shoulder main groove 25, a triangular notch 35 is formed in the shoulder land 21. This notch 35 partially widens the width of the sipe 34.

As shown in Figures 3 and 4, at the location of the notch 28, an inclined surface 36 is formed that is inclined relative to the ground contact surface from the ground contact surface of the center land 23 to the bottom surface of the quarter main groove 27. Although not shown, at the locations of all of the notches 28, 29, and 35, an inclined surface is formed from the ground contact surface of the land to the bottom surface of the main groove as shown in Figures 3 and 4.

A pneumatic tire having the above characteristics is mounted, for example, on the drive side of a vehicle.

As described above, in the pneumatic tire of this embodiment, the center land 23 and the quarter land 24 of the tire axial center region 22 are each provided with slits 30 and sipes 31 that divide these lands 23, 24. The presence of these slits 30 and sipes 31 gives the pneumatic tire excellent traction.

In addition, not all of the grooves on the center land 23 and the quarter land 24 are wide slits 30, but half of the grooves are narrow sipes 31, so that the sipes 31 are easily closed when the lands 23 and 24 are deformed, ensuring the rigidity of the lands 23 and 24. In addition, because the slits 30 and sipes 31 are alternately arranged in the tire circumferential direction, the rigidity of the center land 23 and the quarter land 24 is relatively uniform in the tire circumferential direction.

In addition, the depth of the slits 30 is 10% or more of the depth of the center main groove 26 and the quarter main groove 27, ensuring traction. In addition, the depth of the slits 30 is 40% or less of the depth of the center main groove 26 and the quarter main groove 27, so the slits 30 are not too deep and the rigidity of the center land 23 and the quarter land 24 is ensured.

Although the slits 30 are relatively shallow, the slit bottom sipes 32 are provided at the bottom of the slits 30. Therefore, even if the center land 23 and quarter land 24 wear and the slits 30 become shallower or disappear, the slit bottom sipes 32 ensure traction.

In addition, the total depth of the groove including the slits 30 and the slit bottom sipes 32 is 60% or more of the depth of the center main groove 26 and the quarter main groove 27, so traction is ensured.In addition, the total depth of the groove including the slits 30 and the slit bottom sipes 32 is 90% or less of the depth of the center main groove 26 and the quarter main groove 27, so rigidity of the center land 23 and the quarter land 24 is ensured.

As described above, the pneumatic tire of this embodiment has an excellent balance between traction and the rigidity of the lands 23, 24. Furthermore, because the rigidity of the lands 23, 24 is ensured, the resistance to uneven wear of the lands 23, 24 is improved, and the deformation of the lands 23, 24 is small, energy loss is reduced, and fuel efficiency is improved.

These pneumatic tires have excellent traction properties and are particularly effective when mounted on the drive side of a vehicle.

In addition, in this embodiment, sipes 31, 34 are provided in the wide portions 23a, 24a, 21a of the lands 23, 24, 21, and slits 30, 33 are provided in the narrow portions 23b, 24b, 21b, so that the sipes 31, 34 are longer than the slits 30, 33. This increases the rigidity of the lands 23, 24, 21.

In addition, in this embodiment, the ends of the slits 30, 33 and the ends of the sipes 31, 34 face each other across the main grooves 25, 26, 27, and notches 28, 29, 35 are provided at one of the two facing ends, cutting out the lands 21, 23, 24. At the ends of the slits 30, 33 and the ends of the sipes 31, 34, small corners such as acute angles are formed in the lands 21, 23, 24, but by providing the notches 28, 29, 35 in this manner, small corners are eliminated. Therefore, the rigidity of the corners of the lands 21, 23, 24 can be ensured, and the occurrence of cracks due to large movement of the corners of the lands 21, 23, 24 can be prevented.

In addition, the wide portions 23a, 24a, 21a of the lands 23, 24, 21 have corners of the lands 23, 24, 21 that are smaller in angle than the narrow portions 23b, 24b, 21b. The notches 28, 29, 35 at the ends of the sipes 31, 34 in the wide portions 23a, 24a, 21a ensure the rigidity of the corners of the wide portions 23a, 24a, 21a.

The tire axial center region 22 is subjected to a larger ground pressure than the shoulder land 21. Therefore, the width of the center main groove 26 and the quarter main groove 27 is narrower than the width of the shoulder main groove 25, specifically 70% or less, so that the rigidity of the tire axial center region 22 is ensured, and the center land 23 and the quarter land 24 are less likely to deform even when a large ground pressure is applied, ensuring low fuel consumption.

In addition, the width of the center main groove 26 and the quarter main groove 27 is 30% or more of the width of the shoulder main groove 25, ensuring skid resistance and drainage.

In addition, in the tire axial center region 22, the slits 30 and sipes 31 are aligned on a line on both sides of the tire equator C (i.e., they are aligned on a line on both sides of the tire equator C, and the lines on both sides of the tire equator C are connected at the tire equator C), and extend in a direction that forms a V shape when viewed with the side that touches the ground first facing down during normal tire rotation. Therefore, resistance is less likely to occur when the tire is rotating normal, resulting in good fuel efficiency.

In addition, in this embodiment, the center main groove 26, quarter main groove 27, and shoulder main groove 25 are zigzag main grooves, but the amplitude of the zigzag in the tire axial direction is larger in the order of center main groove 26, quarter main groove 27, and shoulder main groove 25. Therefore, the main groove in the area with the higher ground pressure has a larger zigzag shape, and this results in greater traction when the tread comes into contact with the ground.

In addition, in this embodiment, the shoulder land 21 is also provided with slits 33 and sipes 34, ensuring traction. Here, the slits 33 and sipes 34 are arranged alternately in the circumferential direction of the tire, so the rigidity of the shoulder land 21 is relatively uniform in the circumferential direction of the tire. Therefore, uneven wear is less likely to occur in the shoulder land 21.

Although the shoulder land 21 is susceptible to large lateral forces, the ends of the sipes 34 on the shoulder land 21 on the tire ground contact end E side are closed within the shoulder land 21, ensuring the rigidity of the shoulder land 21. As a result, uneven wear on the shoulder land 21 is unlikely to occur.

In addition, the slits 33 and sipes 34 on the shoulder land 21 are bent and extend in a V-shape when viewed with the side that touches the ground first when the tire is rotating forward facing downwards. This makes it difficult for resistance to occur when the tire is rotating forward, resulting in good fuel efficiency.

Various modifications can be made to the above embodiments.

For example, in the center land 23, quarter land 24, and shoulder land 21, the slits 30, 33 may be provided in the wide portions 23a, 24a, 21a, and the sipes 31, 34 may be provided in the narrow portions 23b, 24b, 21b, in contrast to the above embodiment.

In addition, in the center land 23, quarter land 24, and shoulder land 21, notches such as the notches 28, 29, and 35 in the above embodiment may be provided at the opening ends of the slits 30 and 33, rather than the sipes 31 and 34. In a preferred embodiment, when the slits 30 and 33 and the sipes 31 and 34 are provided in the wide portions 23a, 24a, and 21a, the notches are preferably formed in the wide portions 23a, 24a, and 21a. However, the notches may be formed in the narrow portions 23b, 24b, and 21b.

C...Tire equator, E...Tire ground contact edge, 21...Shoulder land, 21a...Wide portion, 21b...Narrow portion, 22...Tire axial center region, 23...Center land, 23a...Wide portion, 23b...Narrow portion, 24...Quarter land, 24a...Wide portion, 24b...Narrow portion, 25...Shoulder main groove, 26...Center main groove, 27...Quarter main groove, 28...Notch, 29...Notch, 30...Slit, 31...Sipe, 32...Slit bottom sipe, 33...Slit, 34...Sipe, 35...Notch, 36...Inclined surface

Claims (4)

A plurality of main grooves extending in the tire circumferential direction divide the tread into a plurality of lands extending in the tire circumferential direction,
As the main grooves, a shoulder main groove that divides the tread into an axially central region of the tire and shoulder lands on both sides of the shoulder lands, and a plurality of main grooves that divide the axially central region of the tire into a plurality of lands are provided,
Each land in the tire axial center region is provided with a slit and a sipe extending in the tire axial direction and dividing the land,
In a pneumatic tire in which the slits and the sipes are alternately provided in the tire circumferential direction on each land,
A slit bottom sipe, which is a sipe different from the sipe, is provided at the bottom of the slit,
The depth of the slit is 10 to 40% of the depth of the main groove,
The depth of the groove including the slit and the slit bottom sipe is 60 to 90% of the depth of the main groove,
The pneumatic tire is characterized in that the slits and the sipes are aligned on a line on both sides of the tire equator and extend in a direction forming a V shape when viewed with the side that first comes into contact with the ground during normal rotation facing down . An end of the slit and an end of the sipe face each other across the main groove,
2. The pneumatic tire according to claim 1, wherein a notch is provided in one of the two opposing ends. The pneumatic tire according to claim 1 or 2, wherein the width of the main groove in the axial center region of the tire is 30 to 70% of the width of the shoulder main groove. As the main grooves in the tire axial center region, a center main groove overlapping with a tire equator and quarter main grooves adjacent to the center main groove are provided,
the center main groove, the quarter main groove, and the shoulder main groove are zigzag main grooves,
The pneumatic tire according to any one of claims 1 to 3 , wherein the zigzag axial swing width of the tire is greatest in the center main groove, greatest in the quarter main groove, and greatest in the shoulder main groove.

Images