JPH06122302A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To make carcass ply cords lightweight and prevent their rupture by arranging the cords forming a carcass ply at the prescribed tread peripheral angle, and setting the end section of a carcass wound around bead cores to the prescribed positional relation. CONSTITUTION:A pneumatic radial tire is provided with a tread section 1, a pair of side wall sections 2, and bead sections 3, and it is constituted of a carcass 4 having a carcass ply, two belt layers 5a, 5b made of cords arranged, crossed, and extended on the outer periphery side of they carcass 4, and bead cores 6 of the bead sections 3. The tread peripheral angle of the cords forming the carcass ply is set to 75-88 deg., end portions 4b wound from the inside to the outside around the bead cores 6 are located at an interval at the positions on the inner periphery side of the belt layers 5a, 5b, and an interval 0.5-5.0 times the diameter of the carcass ply cord is provided between a carcass main body portion 4a and the wound end portion 4b on a tire shoulder section 7. Thus, the rupture durability of the carcass ply cords can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire, and more particularly to a carcass structure capable of effectively preventing breakage of a carcass ply cord.

[0002]

2. Description of the Related Art As a conventional pneumatic radial tire, a carcass is formed by at least one carcass ply composed of carcass ply cords that form substantially 90 ° with respect to the circumferential direction of the tread, and each end of the carcass is formed. Some parts are wound from the inside to the outside around the bead core, and the winding ends are located at the inner circumference side position of the belt layer with a space between them.In such a pneumatic radial tire, the carcass is wound up. The end part,
By finishing at the position on the inner peripheral side of the belt layer, the tire was lightened and the rigidity was improved.

[0003]

However, in such a prior art, since the carcass ply cord extends at an angle of substantially 90 ° with respect to the circumferential direction of the tread, the load rolling of the tire, especially The carcass, and eventually the tire, did not have sufficient rigidity when rolling under load during turning of the vehicle.

Therefore, by extending the carcass ply cord at an angle smaller than 90 ° with respect to the circumferential direction of the tread, the carcass of one carcass ply is
It has been proposed that the main body portion cord and the winding end portion cord be crossed with each other to increase the rigidity from the bead portion to the tread portion and also to reduce the weight of the tire.

However, according to this, when the tire rolls under load, especially in the shoulder portion, in other words, in the portion between the portion near the maximum width position of the tire and the portion near the belt side edge, There is a problem that the ply cords of the carcass main body portion and the ply cords of the hoisting end portion, which are in different directions from each other, rub against each other, so that the carcass ply cord is likely to be early broken.

The present invention has been made as a result of investigations aimed at solving such problems of the prior art, and an object of the present invention is to realize a reduction in the weight of tires and still to provide a carcass ply. (EN) It is possible to provide a pneumatic radial tire capable of effectively preventing breakage of a cord.

[0007]

A pneumatic radial tire of the present invention includes a tread portion, a pair of sidewall portions and a bead portion, and a carcass formed of a single carcass ply, and an outer periphery of the carcass. A pneumatic radial tire having at least two belt layers each of which is disposed on the side and formed of cords that extend to intersect each other, and a bead core embedded in each bead portion, and forms a carcass ply. The angle of the cord with respect to the circumferential direction of the tread is in the range of 75 to 88 °, and each single part of the carcass is wound from the inside to the outside around the bead core, and each winding end is positioned on the inner circumference side of the belt layer. At a distance from each other, and the tire shoulder portion, that is, the portion near the tire maximum width position and the base portion as described above. In a portion between the up side edge vicinity portion, between the body portion and winding end portion of the carcass, from 0.5 to 5.0 times the carcass ply cord diameter, preferably from 0.7 to
It has an interval of 3.0 times. It should be noted that hard rubber, nylon woven fabric, or another intermediate layer is disposed within the space,
It is preferable that the carcass ply cords are prevented from contacting each other and at the same time, the bending rigidity of the shoulder portion is increased.

More preferably, the tread portion is provided with a circumferential groove extending substantially in the tread circumferential direction at a position substantially corresponding to the winding end of the carcass, and the land portion defined by each circumferential groove is An inclined groove extending in a direction opposite to the extending direction of the carcass ply cord of the outermost carcass portion located on the inner peripheral side of each of the land portions is provided.

[0009]

In the pneumatic radial tire of the present invention, the load on the tire is reduced by providing a distance of 0.5 to 5.0 times the diameter of the carcass ply cord between the body portion of the carcass and the winding end portion at the shoulder portion of the tire. It is possible to sufficiently prevent rubbing between the ply cord of the carcass body portion and the ply cord of the winding end portion during rolling to effectively prevent early breakage of the carcass ply cord.

Here, the distance between the carcass body and the winding end is 0.5 to 5.0 of the carcass ply cord diameter.
If it is less than 0.5 times, the carcass ply cords cannot be effectively prevented from rubbing against each other.
If it exceeds 5.0 times, the weight will increase significantly and the advantage of weight reduction will be lost.

Further, when an intermediate layer for enhancing the bending rigidity of the shoulder portion is provided between the carcass body portion and the winding end portion, maneuverability can be improved.

In addition to the above-mentioned points, the tread portion is provided with a circumferential groove extending substantially in the circumferential direction of the tread located substantially corresponding to the winding end of the carcass, and each circumferential groove defines the circumferential groove. In the land portion, when the inclined groove extending in the direction opposite to the extending direction of the carcass ply cord of the outermost carcass portion located on the inner peripheral side of each of those land portions is provided, in the extending direction of the carcass ply cord, The plysteer component generated as a result can be effectively canceled by the plysteer component caused by the extending direction of the inclined groove, and the steering stability can be greatly improved.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view in the tread width direction showing an embodiment of the present invention. In this example for a tire of size 205/60 R15, 1 is a tread portion, 2 is a pair of sidewall portions connected to the tread portion 1, and 3 is a bead portion continuous with each sidewall portion 2. Are shown respectively.

Reference numeral 4 denotes a carcass as a frame reinforcing layer, and 5 denotes a belt arranged on the outer peripheral side of the crown portion of the carcass 4. This belt 5 is a two-layer belt layer 5a, in this example. It consists of 5b.

Here, the carcass 4 is formed by one piece of the carcass ply 1 made of a nylon cord of 1260d / 2 extending at an angle of 80 ° with respect to the circumferential direction of the tread, and each of the carcass 4 is formed. The end portion is wound around the bead core 6 embedded in the bead portion 3 from the inside to the outside of the tire, and each winding end is attached to the belt 5
Are spaced from each other at the position on the inner peripheral side of.

The main body portion 4a and the winding end portion 4b of the carcass 4 serve as a carcass ply cord in the shoulder portion 7 which is a portion between the portion near the tie maximum width position and the portion near the belt side edge. The nylon cords are placed at intervals of 0.5 to 5.0 times, preferably 0.7 to 3.0 times the diameter. By the way, in the example shown,
It is 1.5 times.

By the way, in the space between the carcass body portion 4a and the winding end portion 4b, a rubber material having a relatively high degree, for example, a Shore A hardness of 90 degrees is provided as the intermediate layer 8. Then, the direct contact of the ply cords of these respective portions is prevented, and at the same time, the bending rigidity of the shoulder portion 7 is increased. As the intermediate layer 8, nylon woven cloth or the like may be used, and a relatively soft rubber material may be used, provided that the thickness is increased.

Further, here, each belt layer
5a and 5b cords in the tread circumferential direction
Steel cords extending in mutually opposite directions at an angle of 20 ° are provided, and a bead filler 9 is arranged on the outer peripheral side of the bead core 6 between the carcass body portion 4a and the winding portion 4b. The hardness, the outer end position in the radial direction, etc. of the bead filler 9 can be appropriately selected as required.

In the figure, 10 and 11 respectively represent a general rubber chafer and a canvas chafer,
12 also shows a general inner liner. Also 1b
Indicates a mini-side rubber layer disposed on the tread side end portion, preferably in a non-contact area, and this mini-side rubber layer 1b
Is also preferably composed of the same rubber composition as the sidewall rubber.

In the tire described above, more preferably, as shown in FIG. 2, the circumferential groove 13 extending in the circumferential direction of the tread portion 1 at a position substantially corresponding to the winding end 4c of the carcass 4. Along with the circumferential groove 13,
Depending on the case, each of the land parts 14 and 15 divided by the circumferential groove including the circumferential direction other than those,
Inclined grooves 16 and 17 extending in a direction opposite to the extending direction of the ply cords of the outermost carcass portion located on the inner peripheral sides of 14 and 15 are provided.

The inclined grooves 16 and 17 are generated by the ply cord of the carcass winding end portion 4b located on the inner peripheral side of the belt 5 and the ply cord of the main body portion 4a located between both winding ends. , Plysteer components in different directions can be effectively offset by their respective plysteer components in different directions, which are generated by the inclined grooves 16, 17.

Comparative Example Below, the breaking durability of the carcass ply cord between the invention tire 1 and the comparative tire 1 shown in FIG. 1 and the invention tire 2 and the comparative tire 2 shown in FIG.
The following is a comparison test of Plysteer and, in turn, steering stability. In addition, the comparative tire 1 forms a carcass with one carcass ply composed of ply cords extending at an angle of 80 ° with respect to the circumferential direction of the tread, and a carcass main body portion and a winding end portion are connected to a tire shoulder portion. The tire is the same as the invention tire 1 except that they are contacted with each other, and the comparative tire 2 has a tread portion in a direction opposite to the extending direction of the ply cords of the outermost carcass portion with respect to the tread circumferential direction. The tire 2 is the same as the inventive tire 2 except that a widthwise groove extending at an angle of 70 ° is formed.

Here, the breaking durability of the carcass ply cord was evaluated by the running time of the drum durability test at low internal pressure, and the steering stability was evaluated by the straight running stability in the actual vehicle test.

The test results are shown in Table 1 as an index using the comparative tire as a control. The larger the index value, the better the result.

[0025]

[Table 1]

[0026]

As is apparent from the above comparative example, according to the present invention, particularly, between the carcass body portion and the winding end portion in the tire shoulder portion, the diameter of the carcass ply cord is 0.5 to 5.0 times. By providing the spacing, it is possible to greatly improve the breaking durability of the carcass ply cord, and the extending direction of the inclined groove formed in the tread portion, and the extending direction of the carcass ply cord of the outermost carcass portion. By making selection under the relation of (1), it is possible to effectively suppress the occurrence of price tear when the tire as a whole is seen, and to provide excellent steering stability.

[Brief description of drawings]

FIG. 1 is a sectional view in the tread width direction showing an embodiment of the present invention.

FIG. 2 is a cross-sectional perspective view showing an aspect of forming an inclined groove on a tread portion.

[Explanation of symbols]

 1 tread part 2 side wall part 3 bead part 4 carcass 4a body part 4b hoisting end part 4c hoisting end 5 belt 5a, 5b belt layer 6 bead core 7 shoulder part 8 intermediate layer 13 circumferential groove 14, 15 land part 16, 17 slope groove

Claims (2)

[Claims] 1. A carcass comprising a tread portion, a pair of sidewall portions and a bead portion, and a carcass made of a single carcass ply, and arranged on the outer peripheral side of the carcass and extending to intersect each other. A pneumatic radial tire comprising at least two belt layers made of cords and a bead core embedded in each bead portion, wherein the cord forming the carcass ply has an angle of 75 to 88 ° with respect to the tread circumferential direction. Each end portion of the carcass is rolled up from the inner side to the outer side around the bead core, and the respective winding ends are positioned at the inner circumference side position of the belt layer and spaced from each other. Is a pneumatic lacquer that is provided between the body of the carcass and the hoisting end with a space 0.5 to 5.0 times the diameter of the carcass ply cord. Giar tire. 2. A tread portion is provided with a circumferential groove extending substantially in the tread circumferential direction at a position substantially corresponding to the winding end of the carcass, and the land portions defined by the respective circumferential grooves are provided with respective land portions thereof. The pneumatic radial tire according to claim 1, wherein an inclined groove extending in a direction opposite to the extending direction of the carcass ply cord of the outermost carcass portion located on the inner peripheral side of the portion is provided.