JP6955428B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire.

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

However, in the conventional pneumatic tire, the outer surface shape of the tread portion is not particularly devised.

Japanese Unexamined Patent Publication No. 2016-43886

An object of the present invention is to provide a pneumatic tire capable of improving braking performance by changing the radius of curvature of the outer surface of the tread portion in the tire meridian cross section.

The present invention provides means for solving the above problems.
It is provided with a carcass ply hung on bead cores on both sides in the tire width direction, a belt wound around the tire radial outer surface side of the carcass ply, and a tread portion provided on the tire radial outer surface side of the belt. Pneumatic tires
The direction when mounted on the vehicle is defined, and when mounted on the vehicle, the direction from the pneumatic tire toward the inside of the vehicle is defined as the inside in the tire width direction, and the direction from the pneumatic tire to the inside of the vehicle is defined. When the direction toward the outside is the outside in the tire width direction,
The tread portion has a first main groove connected in the tire circumferential direction and located in a region including the center in the tire width direction, and a second main groove located inside in the tire width direction.
The outer surface of the tread portion on the inner side in the tire width direction is
A first arc surface that bulges outward in the tire radial direction and is located on the first main groove side.
It has a second arc plane that has a smaller radius of curvature in the tire meridian cross section than the first arc plane and is located inside the first arc plane in the tire width direction.
The intersection position of the first arc surface and the second arc surface is located in the second main groove .
The folded end of the carcass ply is located inside the second main groove in the tire width direction.
In the tread portion, inner ribs are partitioned inside in the tire width direction by the second main groove.
The inner rib is formed with a groove portion that intersects the tire circumferential direction and extends from the ground contact surface of the tread portion beyond the ground contact end.
The groove portion has a deep groove portion located inside in the tire width direction and a shallow groove portion located outside in the tire width direction and shallower than the deep groove portion.
The folded end of the carcass ply provides a pneumatic tire located in a region where the shallow groove is located in the tire width direction.

With this configuration, during braking, the first arc surface having a large radius of curvature acts on the road surface to improve the contact property and improve the braking performance.

In addition, since the folded end of the carcass ply is located inside the second main groove in the tire width direction, the rigidity inside the tire width direction is increased to improve the steering stability performance while maintaining high ground contact. be able to.

In the tread portion, the inner rib is partitioned inside in the tire width direction by the second main groove, and the inner rib is formed with a groove portion that intersects the tire circumferential direction and extends from the ground contact surface of the tread portion beyond the ground contact end. Therefore , the drainage property of the groove can be improved.

The tread portion, the outer table surface in the tire width direction outer side than the first main groove is,
The third arc plane located on the first main groove side and
A fourth arc surface that is continuously located outside the tire width direction of the third arc surface and has a smaller radius of curvature in the tire meridian cross section than the third arc surface.
The equipped Rutotomoni,
Before the third arc surface and the intersection of the fourth arcuate surface across the tire width direction, preferably that are formed grooves crossing the tire circumferential direction.

With this configuration, the ground contact property of the third arc plane at the time of cornering can be improved.

According to the present invention, among the outer surfaces of the tread portion on the inner side in the tire width direction, the central side in the tire width direction is formed by the first arc surface having a large radius of curvature, so that the ground contact property during braking is improved and the braking performance is improved. Can be improved.

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 surface of the first inner rib 10 is composed of a first arc surface 12 having a radius of curvature R1 (here, 950 mm) in a cross section of the tire meridian. On the other hand, the outer surface of the second inner rib 11 has a second arc surface 13 having a radius of curvature R2 (here, 260 mm) smaller than that of the first inner rib 10 in the tire meridian cross section. The intersection position X1 between the first arc surface 12 and the second arc surface 13 is a region where the second main groove 9 in the tire width direction W is formed.

Since the outer surfaces of the first inner rib 10 and the second inner rib 11 are formed in this way, the following effects can be obtained. That is, the portion on the center side in the tire width direction from the second main groove 9, that is, the first inner rib 10, has an outer surface shape having a large radius of curvature, which is closer to a flatter road surface. Therefore, the ground contact property is improved and the braking performance can be improved. Further, the second inner rib 11 having a radius of curvature smaller than that of the first inner rib 10 is formed with the second main groove 9 interposed therebetween. Therefore, the radius of curvature can be reduced significantly without difficulty, and the shape can be flexibly changed inside the tire width direction to increase the rigidity.

The first inner rib 10 is formed with a first groove portion 14 that is inclined from the second main groove 9 toward the outside in the tire width direction in the tire circumferential direction R. The first groove portion 14 is composed of a deep groove portion 14a that gradually deepens the groove depth and communicates with the second main groove 9, and a ridge groove portion 14b. The width dimension of the groove portion 14b 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 second groove portions 15 and third groove portions 16 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 second groove portion 15 is composed of a deep groove portion 15a on the inner side in the tire width direction and a ridge groove portion 15b on the center side in the tire width direction. The third 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 second groove portion 15. Like the second groove portion 15, the third groove portion 16 is composed of a deep groove portion 16a and a ridge groove portion 16b, but the length of the deep groove portion 16a in the tire width direction W is shorter than that of the second groove portion 15. ing. Both the second groove portion 15 and the third groove portion 16 extend inward in the tire width direction beyond the ground contact end. As a result, the drainage property of the second groove portion 15 and the third groove portion 16 is enhanced.

The outer surface of the outer rib 8 includes two arcuate surfaces having different radii of curvature in the tire meridian cross section. The center side of the outer surface of the outer rib 8 in the tire width direction is composed of a third arc surface 17 having a radius of curvature R3 (here, 950 mm, which is the same as the radius of curvature R1) in the tire meridional cross section. Further, the outer surface of the outer rib 8 in the tire width direction is the fourth arc surface 18 having a radius of curvature R4 (here, 260 mm, which is the same as the radius of curvature R2) having a radius of curvature smaller than that of the third arc surface 17 in the tire meridional cross section. It is composed of. The intersection position X2 of the third arc surface 17 and the fourth arc surface 18 is a region in which the fourth groove portion 19 and the fifth groove portion 20, which will be described later, are located in the tire width direction.

Since the outer surface of the outer rib 8 is formed in this way, the ground contact property of the outer rib 8 on the center side in the tire width direction is improved, and the braking performance is improved.

The outer rib 8 is provided with fourth groove portions 19 and fifth groove portions 20 that are inclined toward one side of the tire circumferential direction R from the center side of the tire width direction W to the outside alternately in the tire circumferential direction R. There is.

The fourth groove portion 19 includes a first inclined portion 19a extending in the tire circumferential direction R 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 19a. It has a second inclined portion 19b extending outward in the tire width direction as the inclination angle to the tire increases, and a third inclined portion 19c at the tip thereof. By making the inclination angles of the first inclined portion 19a and the second inclined portion 19b different from each other and forming a bent shape, the rigidity in this portion is increased. The third inclined portion 19c has the same inclination direction as the second inclined portion 19b, but the depth and width dimensions are smaller. The first inclined portion 19a and the second inclined portion 19b ensure drainage, and the occupied volume of the third inclined portion 19c is reduced to suppress a decrease in rigidity on the outer side in the tire width direction.

The fifth groove portion 20 is different from the fourth groove portion 19 in that the first inclined portion 19a is not provided. That is, the fifth groove portion 20 is composed of a fourth inclined portion 20a and a fifth inclined portion 20b.

The region outside the outer rib 8 in the tire width direction is a plain region 21 (hatched portion by a two-dot chain line in FIG. 3) in which the fourth groove portion 19 and the fifth groove portion 20 are not formed. By setting this region as the plain region 21, 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 portion 19c and the fifth inclined portion 20b.

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 22 connected to the bead core 2. The first ply 3a is directly wound around the bead core 2 and extends along the reinforcing layer 23 provided on the bead filler 22 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 24. Incidentally, the carcass ply 3 is the outer surface of the bead core 2 and a bead filler 22 is further covered with a chafer 25.

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-back portion of the second ply 3b.

The folded end E of the second ply 3b is located inside the second main groove 9 in the tire width direction at the inner ribs 10 and 11, and the outer edge of the first belt 4a and the fourth groove 19 or the outer rib 8 at the outer rib 8. It is located between the fifth groove portion 20 and the outer end portion in the tire width direction. Specifically, the distance W in the tire width direction from the side end of the first belt 4a to the folded end E of the second ply 3b is set to W1, the fourth groove 19 or the fifth groove 20 from the outer end in the tire width direction. When the distance W in the tire width direction to the folded end E of the 2-ply 3b is W2, the folded end 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 fourth groove portion 19 or the fifth groove portion 20 in the tire width direction coincides with the position of the folded end E of the second ply 3b.

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

Further, the folded end E inside the tire width direction of the second ply 3b is a region (occupied region) where the second groove portion 15 or the third groove portion 16 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 E on the inner side of the second ply 3b in the tire width direction is a region in the tire width direction W where the ridge portion 15b of the second groove portion 15 or the ridge groove portion 16b of the third groove portion 16 is located. Therefore, the distance from the second ply 3b to the groove bottoms of the second groove portion 15 and the third groove portion 16 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 inclined outward (negative camber). Therefore, when the vehicle goes straight, the contact pressure on the inner ribs 10 and 11 increases.

When the tire 1 is mounted on the vehicle, the inclination direction of the groove formed in each rib is from the outside to the inside of the tire width direction W toward the rotation direction of the tire 1 (when the vehicle moves forward). There is. This improves drainage.

In the fourth groove portion 19 and the fifth groove portion 20 of the outer rib 8, the third inclined portion 19c and the fifth inclined portion 20b , which are the outer portions in the tire width direction, are narrower than the other portions and the depth is suppressed. There is. The outside of the tire width direction beyond the fourth groove portion 19 and the fifth groove portion 20 is a plain region 21. 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 inner ribs 10 and 11, the position of the folded end E of the second ply 3b of the carcass ply 3 is optimized. The folded end E of the second ply 3b is located in the winding region of the belt 4, but is inside the second main groove 9 in the tire width direction. Further, the folded end E of the second ply 3b is farther from the center position O in the tire width direction W on the inner ribs 10 and 11 sides than on the outer rib 8 side. With such a configuration, the rigidity on the inner ribs 10 and 11 side is suppressed as compared with the outer rib 8 side, and it becomes easier to touch the ground. Therefore, the braking performance is improved.

In the outer rib 8, the position of the folded end E of the second ply 3b of the carcass ply 3 is optimized. The folded end E of the second ply 3b extends from the side end of the belt 4 toward the center side in the tire width direction, and sufficiently increases the rigidity of the outer rib 8 on the ground contact end side. However, the folded end E of the second ply 3b is set so as not to exceed the position of the outer end portion of the fourth groove portion 19 in the tire width direction, and the groove bottom of the fourth groove portion 19 or the fifth groove portion 20. It prevents the part from being easily damaged.

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 4a ... 1st belt 4b ... 2nd belt 5 ... Reinforcing belt 6 ... Tread part 7 ... 1st main groove 8 ... Outer rib 9 ... 2nd main groove 9a, 9b ... Inclined surface 10 ... 1st inner rib 11 ... 2nd inner rib 12 ... 1st arc surface 13 ... 2nd arc surface 14 ... 1st groove 14a ... Deep groove 14b ... Asagi Groove 15 ... Second groove 15a ... Deep groove 15b ... Asagi groove 16 ... Third groove 16a ... Deep groove 16b ... Asagi groove 17 ... Third arc surface 18 ... Fourth arc surface 19 ... Fourth groove 19a ... First inclined portion 19b ... 2nd inclined portion 19c ... 3rd inclined portion 20 ... 5th groove portion 20a ... 4th inclined portion 20b ... 5th inclined portion 21 ... Plain area 22 ... Bead filler 23 ... Reinforcing layer 24 ... Belt winding area 25 ... Cha fur

Claims (2)

It is provided with a carcass ply hung on bead cores on both sides in the tire width direction, a belt wound around the tire radial outer surface side of the carcass ply, and a tread portion provided on the tire radial outer surface side of the belt. Pneumatic tires
The direction when mounted on the vehicle is defined, and when mounted on the vehicle, the direction from the pneumatic tire toward the inside of the vehicle is defined as the inside in the tire width direction, and the direction from the pneumatic tire to the inside of the vehicle is defined. When the direction toward the outside is the outside in the tire width direction,
The tread portion has a first main groove connected in the tire circumferential direction and located in a region including the center in the tire width direction, and a second main groove located inside in the tire width direction.
The outer surface of the tread portion on the inner side in the tire width direction is
A first arc surface that bulges outward in the tire radial direction and is located on the first main groove side.
It has a second arc plane that has a smaller radius of curvature in the tire meridian cross section than the first arc plane and is located inside the first arc plane in the tire width direction.
The intersection position of the first arc surface and the second arc surface is located in the second main groove .
The folded end of the carcass ply is located inside the second main groove in the tire width direction.
In the tread portion, inner ribs are partitioned inside in the tire width direction by the second main groove.
The inner rib is formed with a groove portion that intersects the tire circumferential direction and extends from the ground contact surface of the tread portion beyond the ground contact end.
The groove portion has a deep groove portion located inside in the tire width direction and a shallow groove portion located outside in the tire width direction and shallower than the deep groove portion.
The folded end of the carcass ply is a pneumatic tire located in a region where the shallow groove portion is located in the tire width direction. The outer surface of the tread portion on the outer side in the tire width direction with respect to the first main groove is
The third arc plane located on the first main groove side and
It is provided with a fourth arc surface that is continuously located outside the tire width direction of the third arc surface and has a smaller radius of curvature in the tire meridian cross section than the third arc surface.
The pneumatic tire according to claim 1, wherein a groove is formed so as to cross the intersection position of the front third arc surface and the fourth arc surface in the tire width direction and intersect in the tire circumferential direction.

Images