JP6955427B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire.

Conventionally, as a pneumatic tire, a tire in which a folded end of a carcass ply hung between bead cores is positioned within a winding region of a belt is known (see, for example, Patent Document 1).

However, the positional relationship of the folded ends of the carcass ply on the inner rib of the tread portion has not been sufficiently examined.

The present inventors have found that by appropriately setting this positional relationship, the braking performance can be improved by suppressing the binding force on the inner rib side as compared with the outer rib side.

Japanese Unexamined Patent Publication No. 2016-43886

The present invention provides a pneumatic tire capable of exhibiting desired steering stability performance and braking performance by improving ground contact while maintaining desired rigidity by appropriately setting the position of the folded end of the carcass ply. The task is to do.

The present invention provides, as means for solving the above problems, a bead core respectively disposed tire width direction on both sides, a carcass ply which is looped prior SL bead core is wound in the tire radial direction outer side of the front Symbol carcass ply a belt, before SL and a tread portion formed in the tire radial direction outside of the belt, the front Symbol tread portion, by the main grooves leading to an annular tire circumferential direction are formed in a region including the tire width direction center, formed outer ribs and inner ribs, wherein the outer rib is formed out groove portion extending in a direction crossing the tire circumferential direction, wherein the inner ribs are in-side groove extending in the direction crossing the tire circumferential direction The position of the folded end of the carcass ply on the outer rib in the tire width direction is located between the outer edge of the belt and the outer end of the outer groove portion in the tire width direction. position in the tire width direction of the folded end of the carcass ply is positioned on the in-side of the tire width direction of the groove occupied area, to provide a pneumatic tire.

With this configuration, it is possible to improve the ground contact property on the ground contact surface while maintaining the rigidity of the inner rib inside in the tire width direction. Therefore, it is possible to improve the braking performance while improving the steering stability performance at the time of cornering.

The in-side groove portions in the tire width direction outside (center side) preferably has a淺溝portion shallower than other portions.

The in-side groove portions in the tire width direction outside (center side) preferably has a narrowed narrow portion of the width than other portions.

With these configurations, while ensuring the drainage by in side grooves, it is possible to suppress the reduction in rigidity in the tire width direction outside.

The position of the tire width direction of the folded end of the carcass ply is preferably coincides with the position in the tire width direction of the tire width direction outer end of the in-side groove.

Wherein the tread portion, a second main grooves leading to an annular formed in the first tire width direction inner side in the tire circumferential direction of the main groove, before Symbol tire width direction inner side surface of which constitutes the second main grooves It is preferable that the inclination angle with respect to the straight line extending in the tire radial direction by dividing the second main groove into two is larger than that of the outer side surface in the tire width direction.

With this configuration, the rigidity of the inner ribs located inside in the tire width direction divided by the second main groove can be increased.

According to the present invention, since the position of the folded end of the carcass ply on the inner side in the tire width direction is set within the occupied area of the groove portion, the rigidity of the inner rib on the inner side in the tire width direction is maintained and the ground contact property is improved. be able to. Therefore, it is possible to improve the steering stability performance at the time of cornering and the braking performance at the time of braking.

It is a perspective view of the pneumatic tire which concerns on this embodiment. It is a partially developed view which shows the tread part of FIG. It is a meridian cross-sectional view of the pneumatic tire of FIG.

Hereinafter, embodiments according to the present invention will be described with reference to the accompanying drawings. It should be noted that the following description is essentially merely an example and is not intended to limit the present invention, its application, or its use.

FIG. 1 shows a perspective view of a pneumatic tire 1 (racing tire, hereinafter referred to as a tire 1) according to the present embodiment. As shown in FIG. 3, in the tire 1, bead cores 2 are arranged on both sides in the tire width direction W, and a carcass ply 3 is hung between the bead cores 2. A belt 4 is wound around the outer circumference of the carcass ply 3, and a reinforcing belt 5 is wound around the outer circumference thereof. A tread portion 6 is provided on the outer side of the reinforcing belt 5 in the tire radial direction.

With reference to FIG. 2 as well, the tread portion 6 is provided with a first main groove 7 connected in an annular shape in the tire circumferential direction R in a region including the center O in the tire width direction W. The bottom surface of the first main groove 7 is a curved surface having an arcuate cross section, and both side surfaces extending from the curved surface toward the surface of the tread portion 6 are formed of inclined surfaces whose width gradually increases. The outer rib 8 is formed on the outer side of the tread portion 6 in the tire width direction by the first main groove 7.

A second main groove 9 connected in an annular shape in the tire circumferential direction R is provided inside the tread portion 6 in the tire width direction. The second main groove 9 forms the first inner rib 10 and the second inner rib 11 on the inner side in the tire width direction in order from the center side. The bottom surface of the second main groove 9 is a curved surface having an arcuate cross section, and both side surfaces extending from the curved surface toward the surface of the tread portion 6 are composed of inclined surfaces 9a and 9b so as to gradually widen. ing. However, the inclined surface 9a on the inner side in the tire width direction is inclined so as to further widen the groove width than the inclined surface 9b on the outer side. As a result, the rigidity of the second inner rib 11 side is increased.

The outer rib 8 is provided with first groove portions 12 and second groove portions 13 that are inclined toward one side of the tire circumferential direction R from the center side in the tire width direction W to the outside alternately in the tire circumferential direction R. There is.

The first groove portion 12 includes a first inclined portion 12a extending in an inclined direction R in the tire circumferential direction from the vicinity of the first main groove 7 toward the outside in the tire width direction, and a tire circumferential direction R from the first inclined portion 12a. It has a second inclined portion 12b extending outward in the tire width direction as the inclination angle to the tire becomes smaller, and a third inclined portion 12c at the tip thereof. By making the inclination angles of the first inclined portion 12a and the second inclined portion 12b different and forming a bent shape, the rigidity in this portion is increased. The third inclined portion 12c has the same inclination direction as the second inclined portion 12b, but the depth and width dimensions are smaller. The first inclined portion 12a and the second inclined portion 12b ensure drainage, and the occupied volume of the third inclined portion 12c is reduced to suppress a decrease in rigidity on the outer side in the tire width direction.

The second groove portion 13 is different from the first groove portion 12 in that there is no first inclined portion. That is, the second groove portion 13 is composed of a second inclined portion 13a and a third inclined portion 13b.

The region outside the outer rib 8 in the tire width direction is a plain region 14 in which the first groove portion 12 and the second groove portion 13 are not formed. By setting this region as the plain region 14, the rigidity of the outer rib 8 of the tire 1 is maintained at a desired value in combination with the configurations of the third inclined portions 12c and 13b.

The first inner rib 10 is formed with a third groove portion 15 that is inclined from the second main groove 9 toward the outside in the tire width direction in the tire circumferential direction R. The third groove portion 15 is composed of a deep groove portion 15a that gradually deepens the groove depth and communicates with the second main groove 9, and an ascending groove portion 15b. The width of the groove portion 15b gradually decreases while being inclined in the tire circumferential direction R toward the center O in the tire width direction.

The second inner rib 11 is provided with fourth groove portions 16 and fifth groove portions 17 that are inclined in the tire circumferential direction R from the inside to the outside in the tire width direction W alternately in the tire circumferential direction R. The fourth groove portion 16 is composed of a deep groove portion 16a on the inner side in the tire width direction and a ridge groove portion 16b on the center side in the tire width direction. The fourth groove portion 16 is inclined in the tire circumferential direction R from the inside in the tire width direction toward the center side, and is arranged on substantially the same straight line as the third groove portion 15. Like the fourth groove portion 16, the fifth groove portion 17 is composed of a deep groove portion 17a and a ridge groove portion 17b, but the length of the deep groove portion 17a in the tire width direction W is shorter than that of the fourth groove portion 16. ing. Both the fourth groove portion 16 and the fifth groove portion 17 extend inward in the tire width direction beyond the ground contact end. As a result, the drainage property of the fourth groove portion 16 and the fifth groove portion 17 is enhanced.

The carcass ply 3 is composed of a first ply 3a and a second ply 3b that are wound from the inside to the outside so as to surround the bead core 2 and the bead filler 18 connected to the bead core 2. The first ply 3a is directly wound around the bead core 2 and extends along the reinforcing layer 19 provided on the bead filler 18 to the upper side thereof. The second ply 3b is wound around the first ply 3a, and its folded end E extends to the belt winding region 20. The carcass ply 3 is further covered with a chafer 21 on the outer surface side of the bead core 2 and the bead filler 18.

The belt 4 is composed of a first belt 4a wound around the tire radial outer peripheral surface of the carcass ply 3 (second ply 3b) and a second belt 4b wound around the tire radial outer peripheral surface of the first belt 4a. ing. Both side edges of the first belt 4a extend outward and inward in the tire width direction beyond the ground contact end, and cover the folded end E of the second ply 3b.

In the outer rib 8, the folded end E of the second ply 3b is located between the outer edge of the first belt 4a and the outer end of the first groove portion 12 or the second groove portion 13 in the tire width direction. Specifically, the distance in the tire width direction W from the side edge of the first belt 4 a until folded end E of the second ply 3b W1, from the tire width direction outer end portion of the first groove part 12 and the second groove 13 When the distance W in the tire width direction to the folded end E of the second ply 3b is W2, the folded end E of the second ply 3b is arranged so as to satisfy W1> W2. Here, W2 = 0, and the position of the outer end portion of the first groove portion 12 or the second groove portion 13 in the tire width direction coincides with the position of the folded end E of the second ply 3b.

Further, the positions of the folded ends of the second ply 3b are different between the outer ribs 8 and the inner ribs 10 and 11. That is, the distance W in the tire width direction from the folded end on the outer side in the tire width direction of the second ply 3b to the center in the tire width direction is Wout, and the distance from the folded end on the inner side in the tire width direction of the second ply 3b to the center in the tire width direction is set. When the distance W in the tire width direction is Win, the position of the folded end of the second ply 3b is set so as to satisfy Wout <Win.

Further, the folded end of the second ply 3b on the inner side in the tire width direction is a region (occupied region) in which the fourth groove portion 16 or the fifth groove portion 17 is located when viewed in the region of the tire width direction W. As a result, while ensuring the rigidity of the second inner rib 11 inside in the tire width direction, deformation on the ground contact surface is allowed, and braking performance can be ensured. In particular, the folded end of the second ply 3b on the inner side in the tire width direction is a region where the associative groove 16b of the fourth groove 16 or the assault groove 17b of the fifth groove 17 is located. Therefore, the distance from the second ply 3b to the groove bottom of the fourth groove portion 16 and the fifth groove portion 17 is not too short to be easily damaged.

The tire 1 having the above configuration has a determined mounting direction on the vehicle. That is, the outer rib 8 is arranged on the outer portion of the vehicle, and the first inner rib 10 and the second inner rib 11 are arranged so as to be arranged on the inner portion of the vehicle. In this mounted state, the tire radial direction is not perpendicular to the road surface, but is inclined so that the contact patch side is located on the outside. Therefore, when the vehicle goes straight, the contact pressure on the inner rib side increases.

Tire 1, in a mounted state on the vehicle, the inclination direction of the grooves formed on each rib, the width direction center of the direction of the vehicle tire 1 toward the opposite sides (when the vehicle moves forward) direction of rotation ing. This improves drainage.

In the first groove portion 12 and the second groove portion 13 of the outer rib 8, the third inclined portion, which is the outer portion in the tire width direction, is narrower than the other portions and the depth is suppressed. The outside of the tire width direction beyond the first groove portion 12 and the second groove portion 13 is a plain region 14. Therefore, while maintaining drainage, it is possible to suppress a decrease in rigidity in the outer region in the tire width direction and improve steering stability performance during cornering.

In the outer rib 8, the position of the folded end of the second ply 3b of the carcass ply 3 is optimized. The folded end of the second ply 3b extends from the side end of the belt 4 toward the center side in the tire width direction, and the rigidity of the outer rib 8 on the ground contact end side is sufficiently increased. However, the folded end of the second ply 3b is set so as not to exceed the position of the outer end portion in the tire width direction of the first groove portion 12, and the groove bottom portion of the first groove portion 12 or the second groove portion 13. Prevents tires from becoming easily damaged.

In the inner rib, the position of the folded end of the second ply 3b of the carcass ply 3 is optimized. The folded end of the second ply 3b is located in the winding region of the belt 4, but the inner rib side is farther from the center position in the tire width direction than the outer rib side. As a result, the rigidity on the outer rib side is suppressed as compared with the inner rib side, and it becomes easier to touch the ground. Further, the position of the folded end of the carcass ply 3 is set within the occupied area of the fourth groove portion 16 and the fifth groove portion 17. Therefore, it is possible to suppress the rigidity of the first inner rib 10 on the ground contact surface while maintaining the rigidity of the second inner rib 11 on the inner side in the tire width direction. That is, it is possible to improve the steering stability performance at the time of cornering and the braking performance at the time of braking.

The present invention is not limited to the configuration described in the above embodiment, and various modifications can be made.

In the above embodiment, the belt 4 is composed of two belts and the carcass ply 3 is composed of two belts, but the number of these can be freely changed according to the type of the tire 1 and the like.

1 ... Tire 2 ... Bead core 3 ... Carcass ply 3a ... 1st ply 3b ... 2nd ply 4 ... Belt 5 ... Reinforcing belt 6 ... Tread part 7 ... 1st main groove 8 ... Outer rib 9 ... 2nd main groove 10 ... 1st inner rib 11 ... 2nd inner rib 12 ... 1st groove 13 ... 2nd groove 14 ... Plain area 15 ... 3rd groove 16 ... 4th groove 17 ... 5th groove 18 ... Bead filler 19 ... Reinforcing layer 20 ... Belt Tread area 21 ... Chafer

Claims (4)

Bead cores placed on both sides in the tire width direction,
The carcass ply that is hung on the bead core,
A belt wound around the outer side of the carcass ply in the tire radial direction,
A tread portion formed on the outer side of the belt in the tire radial direction and
With
It said tread portion, a main groove leading to an annular tire circumferential direction is formed in a region including the tire width direction center, the outer rib and the inner rib is formed,
The outer rib is formed with an out-side groove extending in a direction intersecting the tire circumferential direction.
Wherein the inner ribs are in side groove extending in the direction crossing the tire circumferential direction are formed,
The position of the folded end of the carcass ply on the outer rib in the tire width direction is located between the outer edge of the belt and the outer end of the out-side groove portion in the tire width direction.
The position of the tire width direction of the folded end of the carcass ply in the inner ribs is positioned on the in-side of the tire width direction of the groove occupied area, the pneumatic tire. The in-side groove portions in the tire width direction center side has a淺溝portion shallower than other portions, the pneumatic tire according to claim 1. The in-side groove portions in the tire width direction center side, has a narrow portion which is narrowed in width than the other portions, the pneumatic tire according to claim 1 or 2. In the tread portion , a second main groove is formed inside the first main groove in the tire width direction and is connected in an annular shape in the tire circumferential direction.
The inner side surface in the tire width direction constituting the second main groove has a larger inclination angle with respect to the straight line extending in the tire radial direction by dividing the second main groove into two as compared with the outer side surface in the tire width direction. The pneumatic tire according to any one of claims 1 to 3.

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