JPH0596906A - Radial tire - Google Patents

Abstract

PURPOSE:To increase uniformity and durability of tire. CONSTITUTION:Multiple bead cores 18a and 18b are positioned roughly in lateral direction of a tire. Both sides 16a (16b) of a sheet of carcass ply for each bead core 18a (18b) are curled about each bead core 18a (18b). Then each curled end 17a (17b) is positioned lower than a flange.

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, and a plurality of the carcass plies are arranged in an overlapping manner. Then, on the outside of the carcass ply 10, the tread 12 and the sidewall 1 are provided.
4 is attached, and the belt 15 is arranged in the tread 12, and both side portions 16a, 16 of each carcass ply 10 are attached.
b and 16c are wound up together in a state of being overlapped with each other by using a single bead core 18 of a bead portion provided with a bead apex 20 as a fulcrum. In the example shown, each side 1
6a, 16b, 16c are wound from the inside (left side of the drawing) of the tire toward the outside (right side of the drawing), and these winding ends are located lower than the rim flange 24 and on the outer surface of the bead apex 20. It is fixed in place.

In FIG. 3, hatching of each cross section is omitted for the sake of convenience, and the respective winding ends 17a, 17b, 17c are painted black.

[0004]

Among the tires having the above structure, particularly for tires used under heavy load or high internal pressure, the thickness of the cord forming the carcass ply 10 is large in consideration of the carcass strength safety factor. It is necessary to increase the height or increase the number of carcass plies.

Here, when the number of carcass plies 10 is increased, the volume around the bead core 18 is correspondingly increased, while the rim diameter is constant, so the distance from the base line BL to the bead core 18 becomes long, which causes There is a drawback that the variation in the set position of the bead core 18 becomes large and the tire uniformity easily deteriorates.

The winding end 1 of each carcass ply 10
When the carcass plies 7a, 17b, 17c are fixed to a position where the carcass ply is easily deformed, for example, a position close to an inflection point shown by a circle A in FIG. 3, these winding ends 17a, 17b, 17
Since a large strain is generated in c and peeling easily occurs from here, the positions of these winding ends 17a, 17b, 17c are lower than the rim flange 24, that is, the carcass ply 10 from the viewpoint of tire weight reduction. It is desirable to set it at a position where there is little deformation. However, in order to securely fix the winding ends 17a, 17b, 17c, it is necessary to shift the positions of the winding ends 17a, 17b, 17c to secure step s, so that all the winding ends 17a to 17c. If the carcass ply is to be stored in the above area, the winding height of the innermost carcass ply both side portions 16c must be set extremely low. Moreover, since such a winding height greatly varies in the production process, The winding up of the both side portions 16c may be insufficient and a good product may not be obtained.

Further, the carcass plies 10 are overlapped with each other over the entire area.
Since all the carcass plies 10 are easily deformed integrally due to the frictional force between them, a large tensile strain or compression strain is generated in the outermost carcass ply side portions 16a and the innermost carcass ply side portions 16c. It is easy and has a disadvantage in strength.

In view of the above circumstances, the present invention improves the uniformity of the tire in a radial tire having a plurality of carcass plies, and at the same time sufficiently secures the winding of each carcass ply, An object of the present invention is to provide a radial tire that can prevent peeling and the like and can disperse the strain generated in each carcass ply to reduce the mechanical load.

[0009]

According to the present invention, a plurality of carcass plies made of tire fabric are superposed, and both sides of these carcass plies are wound up from the inside to the outside of the tire with a bead core as a fulcrum. In a radial tire, a plurality of bead cores are arranged side by side in the width direction of the tire, and one carcass ply is wound on both sides of each bead core with each bead core as a fulcrum, and the height position of this hoisting end is adjusted to the rim. It is set at a position lower than the flange (Claim 1).

[0010]

According to the above radial tire, the carcass ply is wound up one by one for each bead core. Therefore, even if a large number of carcass plies are arranged, the volume of the portion inside the tire cross-section height with respect to the bead core is small. The size of the bead core does not increase, and therefore the variation in the set position of the bead core does not increase.

Further, since both sides of each carcass ply are not bundled with each other but are rolled up independently of each other at each bead core, the step s as shown in FIG. It is possible to fix the winding end without providing it, and thus it is possible to set all the winding heights to be substantially equal. For this reason, it is possible to set the position of each winding end to a position lower than the rim flange and to reliably perform winding.

Furthermore, since both sides of each carcass ply are deformed independently of each other, the strain generated on both sides of each carcass ply is dispersed, and the load on strength is reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. In addition, the structure of the portion other than the bead portion in FIG.
Is completely equivalent to, and the description thereof is omitted here.

In the figure, reference numeral 10 denotes a carcass ply made of a tire fabric composed of a large number of cords, and in this example, two carcass plies 10 are arranged so as to overlap each other. On the other hand, bead apex 2 in the bead area
Two bead cores 18 with 0a and 20b respectively
a and 18b are provided side by side in the width direction of the tire.
Then, both side portions 16 of the two carcass plies 10 are
a and 16b are the inner sides (left side of the figure) to the outer side (right side of the figure) of the tire with the bead cores 18a and 18b as fulcrums, respectively.
It is wound up toward the
b is fixed to a position lower than the rim flange 24 (a lower position in the figure). That is, the winding end 17
a, 17b hoisting height dimension h from the base line BL
c is set to be smaller than the height dimension hf of the rim flange 24.

In FIG. 1, hatching of each cross section is omitted for the sake of convenience, and the winding ends 17a and 17b are painted black.

According to this structure, each bead core 1
Since the carcass ply 10 is rolled up one by one for 8a and 18b, two carcass ply 10
Even if the carcass ply 10 is arranged, the volume of the portion inside the tire cross-section height (lower side in the figure) than the bead cores 18a and 18b does not become larger than the case where one carcass ply 10 is arranged. Therefore, variations in the set positions of the bead cores 18a and 18b do not become large, and the tire uniformity is kept good.

Both sides 16 of each carcass ply 10
Since the a and 16b are not bundled into one and are wound independently of each other in the bead cores 18a and 18b, the step s as shown in FIG. 3 is performed between the winding ends 17a and 17b. It is possible to fix the winding ends 17a and 17b without providing them, and thus it is possible to set all the winding heights to be substantially equal. Therefore, while setting the positions of the winding ends 17a and 17b to be lower than the rim flange 24, it is possible to secure a sufficient winding size for each of the side portions 16a and 16b.

Further, both sides 1 of each carcass ply 10
Since 6a and 16b are not deformed integrally as in the prior art, but are deformed independently of each other, the strains generated on both sides 16a and 16b of each carcass ply are dispersed, thereby increasing the strength. Load is reduced and the durability of the tire as a whole is improved.

Next, a second embodiment will be described with reference to FIG. Here, while three carcass plies 10 are arranged, two bead cores 18a and 18b are arranged for the bead cores as in the above-mentioned embodiment, and the innermost carcass ply both side portions 16a and the intermediate carcass ply both side portions are arranged. 1
6b are respectively wound around the bead cores 18a, 18b as fulcrums, and the outermost carcass ply side portions 1
6c is arranged as a reinforcing layer on the outside of the bead apex 20b.

As shown in this embodiment, in the present invention, the number of carcass plies does not necessarily match the number of bead cores, and a part of the carcass plies may be arranged as a reinforcing layer. Also, the carcass ply 10
The specific number of sheets and the specific number of bead cores may be appropriately set according to the application of the tire and the like.

* Experimental data Various tests were conducted on the conventional product shown in FIG. 3 and the product of the present invention shown in FIGS. The results are shown in Tables 1 to 3 below.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

[Table 3]

The following can be said from these data.

(A) The radial tires in both examples are superior in tire uniformity as compared with conventional products (Table 1).

(B) As a result of a bead durability test, all the tires were damaged due to breakage of the bead portion.
The product of the present invention has a longer damage time to tire damage than the conventional product (Table 2).

(C) Compared with the conventional product, the tire of the first embodiment is particularly excellent in riding comfort, and the tire of the second embodiment is excellent in straight running stability, responsiveness, and cornering stability (Table 3).

[0029]

As described above, according to the present invention, a plurality of bead cores are arranged substantially in the width direction of the tire, and each bead core serves as a fulcrum to wind up both sides of one carcass ply. Therefore, even if a large number of carcass plies are arranged, the volume of the portion inside the tire cross-section height from the bead core does not become large. Therefore, the variation in the set position of the bead core does not increase, and this has the effect of improving the tire uniformity.

Further, since both sides of each carcass ply are not bundled with each other but are wound independently of each other in each bead core, the winding ends are fixed without providing a step between the winding ends. Therefore, it is possible to set all the winding heights to be almost equal. Therefore, the position of each winding end can be set to a position lower than the rim flange, and the winding can be performed reliably, and it is possible to reliably prevent a large distortion from occurring at the winding end.

Further, since both sides of each carcass ply are deformed independently of each other, the strain generated on both sides of each carcass ply is dispersed, the load on the strength is reduced, and the durability of the tire is improved. Has the effect of improving.

[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 17a, 17b Winding Ends 18a, 18b Bead Core 24 Rim Flange

Claims (1)

[Claims] 1. A radial tire in which a plurality of carcass plies composed of tire fabrics are superposed, and both side parts of these carcass plies are wound up from the inside of the tire to the outside with a bead core as a fulcrum,
A plurality of bead cores are arranged side by side in the width direction of the tire, and both sides of one carcass ply are rolled up for each bead core with each bead core as a fulcrum, and the height position of this winding end is lower than the rim flange. A radial tire characterized by being set to the position.