JPS61268505A - Radial tire with high internal pressure - Google Patents

Abstract

PURPOSE:To improve durability and reduce weight by forming a carcass with a composite material in which plies of nylon cord are laminated on the both sides of an aramid fiber cord, in a tire for an aircraft, etc. stated in the head line. CONSTITUTION:A composite material is formed by laminating plies of nylon cord 2, 4 each on both sides of a center ply 3 of aramid fiber cord, to constitute a carcass C. This carcass C is folded back and stopped at around a pair of right and left bead cores. And, a belt layer B is formed by plies of nylon cord. By this construction, high durability and light weight can be obtained.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention provides improved durability during running under high internal pressure,
This invention relates to radial tires that have achieved weight reduction, particularly radial tires for aircraft and motorcycles.

[Conventional technology]

In general, high internal pressure tires, especially aircraft tires, rotate at relatively high speeds and are subject to large loads, so the amount of deformation is quite large. Therefore, when the tire deforms, the carcass cord is subjected to large compressive strain, and for this reason, organic fiber cords that are resistant to compressive strain, such as nylon fiber cords, are used in the carcass of this type of tire. However, in order to maintain a specified strength using organic fiber cords such as nylon, it is necessary to increase the number of plies, which increases the wall thickness of the tire and reduces the heat dissipation effect.
This results in an increase in tire weight.

Therefore, as a method of reducing the tire wall thickness and weight of the tire, it has been proposed that aramid (trade name: Kev2) be used for carcass cords. but,
While this aramid has high rigidity, it has the disadvantage of being weak against compressive force, and is therefore unsuitable for use in aircraft tires, which require a large amount of deformation.

[Problem to be solved]

An object of the present invention is to provide a radial tire that achieves high-speed durability and reduced tire weight while compensating for the disadvantage of aramid in that it is weak in compressive force.

[Technical means]

The present invention provides a radial tire comprising a carcass consisting of a plurality of plies whose ends are folded back and locked around a pair of left and right bead cores, and a belt layer disposed on the crown side of the carcass, wherein the carcass is This is a high internal pressure radial tire characterized by being composed of a ply of a composite material in which a ply of aramid fiber cord is laminated with a ply of nylon fiber cord on both sides.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the right half of a sectional view of the radial tire of the present invention. In the figure, a radial tire T has a carcass C consisting of three plies 2.3.4 folded back around a bead core 1 from the inside to the outside, and two plies 5.6 on the outside of the crown portion of this carcass C. A belt layer B consisting of a belt layer B, and four plies 7 further outside this belt layer.
A band ■ consisting of 8.9.10 is arranged. Here, in the carcass C, an aramid fiber cord ply is used for the intermediate ply 3, and a nylon fiber cord ply is used for the plies 2.4 on both sides thereof. Tires are subject to repeated compression and expansion deformation when running, but the highly rigid aramid fiber cords are weak against compression forces, resulting in poor durability. Therefore, by arranging deformed nylon fiber cords that are resistant to compression deformation on both sides, the ply of the nylon fiber cord is subjected to compressive force, thereby protecting the ply of the aramid fiber cord. Furthermore, aramid fiber cords are said to have poor adhesion to rubber, and it is necessary to minimize the shear force between the rubber and fiber cords to prevent them from peeling off. , rubber and aramid fiber cord surface can reduce shear force. Note that the cords of the carcass of the present invention have a radial structure or a semi-radial structure, and are arranged at an angle of 75° to 90° with respect to the tire circumferential direction.

Next, in the present invention, a belt layer is disposed outside the crown portion of the carcass. The ply cord used in the belt layer is an organic fiber cord, for example, an organic fiber cord such as nylon, polyester, rayon, or aramid.

In aircraft tires, the amount of deformation in the crown section is large, and therefore, if a highly rigid cord ply such as steel is present in this region, the deformation of the belt layer will not be able to follow the deformation of the adjacent carcass, and the plies between the two will be deformed. Volatility will occur.

In particular, the cord of the belt layer is preferably made of nylon, its angle is set in the range of 5° to 30° with respect to the tire circumferential direction, and the number of plies used is in the range of 2 to 6.

Next, in the present invention, it is preferable that a band (2) in which cords are arranged substantially balanced with respect to the circumferential direction of the tire is disposed further outside the belt (T-). This is to prevent so-called lifting, in which the tire crown protrudes due to centrifugal force due to high-speed rotation, to occur in tires used for high-speed running, such as aircraft tires. Here, the band is used in a range of 1 to (il'i), and the cord is an organic fiber cord such as nylon, polyester, or rayon.

Next, in the present invention, a bead apex 11 is arranged between the carcass and its folded part, and this bead apex is preferably made of hard rubber with a JIS height of 65' to 95°, or a combination of the hard rubber and the JIS height of 50° to 95°. 65° hard rubber, or the hard rubber and JTS altitude 50'~6
It is also possible to use soft rubber of 5°.

〔Example〕

Tires with tire size H46X18R20 and the structure shown in Figure 1 were manufactured according to each specification in Table 1, and the internal pressure was 13 k.
g/ctA, load 11i 1 B, 8) 70) The stress distribution of the carcass was calculated using finite element property under the following conditions. The results are shown in FIG. 2 for Example and FIG. 3 for Comparative Example 1. As can be seen from the figure, large compressive stress is observed in the sidewall area of the inner ply of both tires of Comparative Example 1 in which aramid fiber cord was used for the carcass, but in both examples, compressive stress was not observed in the ply of aramid fiber cord. It turns out there isn't. From this, it can be inferred that the durability of the example is considerably improved.

On the other hand, in a drum test, the high-speed durability of the tire was evaluated by increasing the load twice the standard value, accelerating the speed from 0 to 225 MPH in 57 seconds, and observing the tire damage state. The example shows an improvement in its performance. Further, the embodiments of the present invention can be applied to conventional bias tires (
Compared to Comparative Example 2), it is possible to significantly reduce the weight.

〔Effect of the invention〕

As mentioned above, in the present invention, a ply of aramid fiber cord is used for the carcass of the tire, and plies of nylon fiber cord are used on both sides of the ply of the aramid fiber cord. It improves compression resistance, which is the weak point of fiber cords, maintains high-speed durability, and makes tires lighter.

[Brief explanation of drawings]

FIG. 1 is the right half of a cross-sectional view of a radial tire, and FIGS. 2 and 3 are graphs showing stress distribution in the tire carcass. 1゛ - Tire, B - Belt layer, ■ - Band, ■ - Bead core, C - Carcass. Patent distributor Sumitomo Rubber Industries Co., Ltd. Representative Patent Attorney Tadashi Naemura 1st WA 11b Yami Neho Tadashi W (0 Yuu υ June 17, 1985)

Claims (3)

[Claims] (1) A radial tire comprising a carcass consisting of a plurality of plies whose ends are folded back and locked around a pair of left and right bead cores, and a belt layer disposed outside the crown portion of the carcass, wherein the carcass is made of aramid. A high internal pressure radial tire characterized by being made of a composite material in which a ply of fiber cord is laminated with plies of nylon fiber cord on both sides. (2) The radial tire according to claim 1, wherein the cord of the belt layer is made of nylon. (3) The radial tire according to claim 1, wherein a band in which cords are arranged substantially parallel to the circumferential direction of the tire is disposed on the outside of the belt layer.