JPH0596905A - Radial tire - Google Patents

Abstract

PURPOSE:To increase durability of tire and reduce its weight. CONSTITUTION:In a radial tire in which both sides 16 of a carcass ply 10 are curled from the inner side to the outer side of the tire with a bead core 18 as a pivot, a curled end of the carcass ply 10 is pinched between the bead core 18 and a bead apex 20, or the bead core is divided into a No.1 and No.2 bead cores 18a and 18b in tire height direction of tire cross section and the curled end of the carcass ply 10 is pinched between them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radial tire in which an end of a carcass ply is wound around a bead core as a fulcrum.

[0002]

2. Description of the Related Art FIG. 3 shows an example of the structure of a conventional radial tire. In the figure, 10 is a carcass ply made of a tire fabric composed of a large number of cords, a tread 12 and a sidewall 14 are attached to the outer side thereof, and a belt 15 is disposed inside the tread 12, Both side portions 16 of the ply 10 are wound around a bead core 18 of a bead portion having a bead apex 20 as a fulcrum. In the illustrated example, the both side portions 16 are wound from the inside (left side of the drawing) of the tire toward the outside (right side of the drawing), and the winding end is located at a position lower than the rim 24 and on the outer surface of the bead apex 20. It is fixed in place. Further, after the winding is performed, the reinforcing layer 22 is attached from the outside of the both side portions 16.

[0003]

Generally, the winding height PH of the carcass ply both side portions 16 (that is, the distance from the base line BL to both winding ends of the carcass ply) PH varies in the production process. If the hoisting height PH deviates from an appropriate value, peeling is likely to occur at the hoisting end portion, resulting in a problem that the durability of the tire is significantly reduced. In addition, in order to securely fix both winding ends of the carcass ply, it is necessary to set the winding height PH to a certain degree, but the weight of the tire increases as the winding height PH increases in this way. This greatly hinders the weight reduction of tires.

In view of such circumstances, it is an object of the present invention to provide a radial tire in which the winding end of the carcass ply is less likely to be damaged and the overall weight of the tire can be reduced.

[0005]

SUMMARY OF THE INVENTION The present invention comprises a carcass ply composed of a tire fabric, and both sides of the carcass ply are wound up from the inside of the tire to the outside with a bead core of a bead portion having a bead apex as a fulcrum. In the obtained radial tire, the winding end of the carcass ply is sandwiched between the bead core and the bead apex (claim 1).

Further, according to the present invention, the bead core is divided into a first bead core and a second bead core in the tire cross-section height direction, and the first bead core is arranged more inward than the second bead core in the tire cross-section height direction. In addition, both sides of the carcass ply are wound around the first bead core as a fulcrum, and the winding ends are sandwiched between the first bead core and the second bead core. 2).

[0007]

According to the radial tire of claim 1, first, the carcass ply is positioned at its both ends (winding end) between the bead core and the bead apex.
A large strain is less likely to occur at both ends of the carcass ply, so that the starting point of carcass ply damage can be eliminated. Further, since the winding height of this carcass ply is sufficient to ensure that the winding end is located between the bead core and the bead apex,
Unlike the conventional case, it is not necessary to secure a large hoisting height, which reduces the width dimension of the carcass ply and reduces the tire weight accordingly.

According to the radial tire of claim 2, the carcass ply has both winding ends positioned between a first bead core and a second bead core which are divided into two. Similar to the tire of item 1,
Excessive strain is less likely to occur at the winding end of the carcass ply, the starting point of damage to the carcass ply can be eliminated, and the width dimension of the carcass ply can be reduced. Moreover, the bead apex is generally formed of a relatively flexible material such as rubber, while the bead core is generally formed of a material having high rigidity such as a steel wire, so that the first bead core and the second bead core are formed. By sandwiching the rolled-up end of the carcass ply with the bead core, the fixing strength is further increased as compared with the case where the bead core and the bead apex are sandwiched.

[0009]

1 shows a bead portion of a radial tire according to a first embodiment of the present invention. The structure of the other parts is exactly the same as that of FIG. 3, and the description thereof is omitted here.

In the figure, 10 is a carcass ply made of a tire fabric composed of a large number of cords. Both sides 16 of the carcass ply 10 have a cross section of approximately 3
It is wound around a bead core 18 of a bead portion including a square bead apex 20 as a fulcrum, and more specifically, it is wound from the inside (left side of the figure) of the tire toward the outside (right side of the figure). A characteristic of this tire is that the winding ends of the both side portions 16 have the bead core 1
8 and the bead apex 20 are sandwiched and fixed.

As a method of manufacturing this radial tire,
Bead core 18 and bead apex 20 as before
Instead of setting and on the carcass ply 10 at the same time, only the bead core 18 is first set on the carcass ply 10, and the both side parts 16 of the carcass ply 10 are wound around the bead core 18 as a fulcrum.
The bead apex 20 may be set so that the winding end of the bead is sandwiched.

According to such a structure, the winding ends of the both side portions 16 of the carcass ply 10 are positioned between the bead core 18 and the bead apex 20, so that the bead apex 20 can be placed outside the bead apex 20 as in the conventional case. Excessive strain is less likely to occur at both winding ends as compared with the case where both winding ends are positioned, whereby the starting point of carcass ply damage can be eliminated. The carcass ply 10 needs to have a winding height sufficient to position the winding end between the bead core 18 and the bead apex 20, so that the width of the carcass ply 10 can be reduced. Therefore, the weight of the tire as a whole can be reduced accordingly.

Next, a second embodiment will be described with reference to FIG. Here, the bead core 18 in the above-described embodiment is divided into a first bead core 18a and a second bead core 18b, which are arranged in the tire cross-section height direction (vertical direction in the drawing). Is the second
Is arranged on the inner side (lower side in the figure) of the tire cross section in the height direction of the tire. Then, both sides 1 of the carcass ply 10 with the first bead core 18a as a fulcrum.
6 is wound from the inside to the outside, and the winding ends of the both side portions 16 are sandwiched between the bead cores 18a and 18b.

As a method of manufacturing this tire, first, only the first bead core 18a is set on the carcass ply 10, and the both side portions 16 of the carcass ply 10 are wound up with the first bead core 18a as a fulcrum, and then this Bead apex 2 with the winding ends of both sides 16 sandwiched
The second bead cores 18b with 0 may be set.

Even in such a structure, as in the first embodiment, the carcass hoisting height is reduced while the side portions 16 of the carcass are prevented from being damaged, thereby improving the durability and weight of the tire. You can Moreover, in the structure shown in the first embodiment, the carcass ply 10 is made up of the bead apex 20 formed of a relatively soft material such as rubber.
While sandwiching both side portions 16 of the two, in the second embodiment, two bead cores 1 having a relatively high rigidity, such as steel wires, are used.
Since the winding ends of both side portions 16 of the carcass ply 10 are sandwiched by 8a and 18b, the fixing strength thereof can be further increased.

In the present invention, regardless of the number of carcass plies 10, the number of carcass plies 10 may be appropriately set according to the application of the tire. Further, the tire shown in each of the above embodiments may be provided with a reinforcing layer 22 as shown in FIG.

[0017]

As described above, the present invention is a radial tire in which both sides of a carcass ply are wound from the inside of the tire to the outside with a bead core as a fulcrum, and the winding end of the carcass ply is between the bead core and the bead apex. Alternatively, since it is sandwiched between the first bead core and the second bead core that are divided in the tire cross-section height direction, large distortion occurs at the winding end of the carcass ply, causing peeling and the like. It is possible to improve the durability of the tire by preventing the above, and to reduce the winding height of the carcass ply, that is, the width dimension of the carcass ply, thereby reducing the weight of the tire. There is.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a radial tire according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a radial tire according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view showing an example of a conventional radial tire.

[Explanation of symbols]

 10 carcass ply 16 both sides of carcass ply 18 bead core 18a first bead core 18b second bead core 20 bead apex

Claims (2)

[Claims] 1. A radial tire comprising a carcass ply composed of a tire fabric, wherein both sides of the carcass ply are wound up from the inside of the tire to the outside with a bead core of a bead portion having a bead apex as a fulcrum. A radial tire in which the winding end of the ply is sandwiched between the bead core and the bead apex. 2. A radial tire in which a carcass ply composed of a tire fabric is provided, and both sides of the carcass ply are rolled up from the inside of the tire to the outside with the bead core of the bead portion as a fulcrum, in which the bead core has a tire sectional height. The first bead core and the second bead core in the depth direction, the first bead core is arranged more inside than the second bead core in the tire cross-section height direction, and the carcass ply is supported by the first bead core as a fulcrum. A radial tire characterized in that both side portions are wound up and the winding end is sandwiched between the first bead core and the second bead core.