JPH0624207A - Radial tire for motorcycle - Google Patents

Abstract

PURPOSE:To enhance the amenity in a car cabin by forming a belt layer from an inner and an outer layer, and forming the inner layer from two or more cut plies inclining at an angle of 35-60 deg. to the equator of a tire. CONSTITUTION:A belt layer 7 consists of an inner layer 9 outside in radial direction of a carcass 6 and an outer layer 10 situated outside of this inner layer 9 in the radial direction. The inner layer 9 consists of two or more cut plies whose belt cords of organic fiber incline at an angle of 35-60 deg. to the tire equator C and which overlap inside and outside in the radial direction. The outer layer 10 is made from band-shaped ply of such a structure that a long stretching cord or cords are of aromatic polyamide fiber is covered with topping rubber, and this band-shaped ply is wound spirally inclined at a minor angle to the tire equator C to form a spirally wound ply, wherein the width of the outer layer 10 is 0.4-0.7 as large as the tread width TW in an arrangement centering on the tire equator C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radial tire for a motorcycle capable of improving both high speed running performance and riding comfort.

[0002]

2. Description of the Related Art In a conventional motorcycle, a carcass uses a ply having organic fiber cords in a radial arrangement, and a belt layer is a cut ply in which the belt cords are arranged at an angle of 17 to 30 ° with respect to the tire equator. By using it, the rigidity of the tread has been maintained and stable running has been achieved.

[0003]

However, with the spread of highways in recent years, there is an increasing demand for higher speeds even in motorcycles, and when running at high speed with a tire having the above-mentioned belt layer structure, the tread crown portion is increased. There is a problem that lifting occurs.

[0004]

In order to solve the above-mentioned problems, for example, a tread crown portion is reinforced and lifted by providing a reinforcing layer in which nylon fibers are spirally wound in the tire circumferential direction on the outside of the belt layer having the above structure. There are also those designed to prevent the occurrence of.

However, although the lifting can be slightly prevented by spirally winding the nylon fiber as described above, when the vehicle travels at a high speed, the tread portion is lifted, so that the running stability is lowered and the durability is deteriorated. The problem has not been completely resolved. Further, the rigidity of the tread crown portion is increased, so that the riding comfort is deteriorated.

The inventor has found that the material of the cord, which greatly affects the rigidity and elasticity of the belt layer, particularly the tread portion,
The present invention has been completed by re-examining the arrangement angle of the cords and finding that the above problems can be solved by making the cords and materials different from the conventional ones.

According to the present invention, the belt layer is formed of two layers, that is, the cut ply and the ply formed by spirally winding the strip-shaped ply, and the inclination of the cord of the cut ply is larger than that of the conventional one, and the material of the cord of the strip-shaped ply is changed. The purpose of the present invention is to provide a radial tire for a motorcycle, which is capable of preventing lifting during high-speed traveling, improving traveling stability, and improving riding comfort to solve the above problems by making the vehicle strong and strong.

[0008]

SUMMARY OF THE INVENTION The present invention is a carcass of a radial arrangement using a carcass cord of an organic fiber which folds around a bead core of a bead part from a tread part to a sidewall part, and inside the tread part and A radial tire for a motorcycle having a belt layer arranged on the outer side of the carcass, wherein the belt layer comprises an inner layer on the outer side in the radial direction of the carcass and an outer layer on the outer side in the radial direction of the inner layer, The inner layer is composed of two or more cut plies in which belt cords of organic fibers are inclined at an angle of 35 to 60 degrees with respect to the tire equator and overlap inward and outward in the radial direction, and the outer layer is one or more using aromatic polyamide fibers. Spiral winding formed by spirally winding a strip-shaped ply with a long cord covered with topping rubber at a small angle to the tire equator Together using ply, the outer layer is 0.4 times or more and 0.7 times or less the width of the tread width,
Moreover, it is a radial tire for motorcycles, which is characterized by being arranged around the tire equator.

[0009]

The belt layer is composed of an inner layer and an outer layer, and the inner layer is made of a belt cord made of organic fiber and is attached to the equator of the tire 3
Two or more cut plies that are inclined at 5 to 60 degrees are stacked. Therefore, in the inner layer, the belt cord cooperates with the carcass cord of the carcass to maintain the hoop effect, and reinforces the tread portion in substantially the entire area where the inner layer overlaps with the carcass to maintain rigidity.

The inclination of the belt cord is 17 to 30 ° with respect to the tire equator in the conventional belt cord, but in the constitution of the present invention, the inclination angle is large as described above, that is, it approaches the inclination of the carcass cord. As a result, it is possible to prevent the rigidity of the tread portion from becoming excessive, and to improve the riding comfort.

In addition, the outer layer is formed by spirally winding a band-shaped ply using aromatic polyamide fiber. Since this aromatic polyamide fiber has strength equivalent to that of steel and is lighter than steel, the tire weight It is possible to strongly tighten the inner layer without increasing, to prevent lifting of the tread portion, improve high speed running performance and improve durability.

Since the strip-shaped ply uses a long cord, by spirally winding it, the running stability is improved during straight traveling, particularly when traveling straight at a high speed, without causing seams of cords unlike the cut ply. Moreover, since the spiral winding has a small inclination of the belt-shaped ply with respect to the tire equator, the stability of straight traveling is increased and the high-speed traveling performance can be further enhanced.

If the width of the outer layer is less than 0.4 times the tread width, the effect of suppressing lifting during running at high speed is poor, and even if it exceeds 0.7, the effect of suppressing lifting does not change. Tire weight increases and cost increases.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 4, a radial tire 1 for a motorcycle
Has a tread portion 2, a sidewall portion 3 extending from both ends thereof toward the tire radial inner side, and a bead portion 4 located at an inner end of the sidewall portion 3 in the tire radial direction. The tire 1 includes a carcass 6 in which a main body portion 6a extending from the tread portion 2 through the sidewall portion 3 to the bead portion 4 is provided with a winding portion 6b for winding up the bead core 5 from the inner side in the tire axial direction to the outer side. , A belt layer 7 disposed inside the tread portion 2 and outside the carcass 6 in the radial direction, and in the tire radial direction outside of the bead core 5 and the winding portion 6b of the carcass 6.
A bead apex 8 having a triangular cross section is erected between the and the main body portion 6a.

The carcass 6 is composed of one or more carcass plies having a carcass cord inclined at an angle of 75 to 90 ° with respect to the tire equator C, and in the present embodiment, one carcass ply, the carcass cord being nylon, Organic fiber cords such as rayon, polyester and aromatic polyamide are used.

The belt layer 7 comprises an inner layer 9 arranged on the outer side of the carcass 6 in the radial direction and an outer layer 10 arranged on the outer side of the inner layer 9 in the radial direction.

The inner layer 9 has two or more layers that are radially inward and outward,
In this embodiment, it is composed of two cut plies 11, 11.
The width OW of the inner layer 9 in the tire axial direction is preferably 0.8 times or more and 1.0 times or less of the tread width TW which is the distance between the edges E of the tread portion 2. Further, these cut plies 11, 11 are belt cords 12 made of organic fiber cords such as nylon, rayon, polyester, aromatic polyamide, etc. with respect to the tire equator C, 35 ° -60 °
Therefore, the cords in the belt layer of a normal tire are inclined at a large angle as compared with 15 to 30 °, and the belt cords 12 and 12 in the two cut plies 11 and 11 intersect each other. It is arranged in the direction.

The inner layer 10 is formed by spirally winding a long strip ply 13 around the inner layer 9.

As shown in FIG. 3, the strip-shaped ply 13 is formed by embedding one long cord 14 in the present embodiment, or one long cord 14 in this embodiment, in a topping rubber 15. An organic fiber cord made of aromatic polyamide is used, and its elastic modulus is preferably 600 kgf / mm or more. In this embodiment, the topping rubber 15 has a rectangular cross section. Alternatively, the two long cords 14 may be embedded together in the topping rubber 15.

As shown in FIG. 4, the band-shaped ply 10 is
The spiral wound ply 16 is formed by arranging one or more, two in this embodiment, spirally and wound at a small angle with respect to the tire equator C to form a spiral wound ply 16.
6 forms the outer layer 10. The outer layer 10 has a width of 0.4 times or more and 0.7 times or less of the tread width TW, and is arranged around the tire equator C.

[0021]

As described above, in the radial tire for a motorcycle of the present invention, the belt layer is formed by the inner layer and the outer layer, and the inner layer is inclined at an angle of 35 to 60 degrees with respect to the tire equator as compared with the conventional tire. Since it is formed by two or more cut plies, the riding comfort can be improved. Further, since the outer layer is composed of a spirally wound ply formed by spirally winding a long cord made of aromatic polyamide fiber,
Lifting at high speeds can be suppressed without increasing tire weight, and high speed running performance can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a developed plan view schematically showing an arrangement of a carcass and a belt layer.

FIG. 3 is a perspective view illustrating a belt-shaped ply.

FIG. 4 is a cross-sectional view showing winding of a strip ply.

[Explanation of symbols]

 2 tread part 3 sidewall part 4 bead part 5 bead core 6 carcass 7 belt layer 9 inner layer 10 outer layer 11 cut ply 12 belt cord 13 belt-shaped ply 14 long cord 15 topping rubber C tire equator OW width TW tread width

Claims (1)

[Claims] 1. A carcass of a radial arrangement using an organic fiber carcass cord that folds around a bead core of a bead part from a tread part to a sidewall part, and is arranged inside the tread part and outside the carcass. A radial tire for a motorcycle having a belt layer, wherein the belt layer comprises an inner layer on the outer side in the radial direction of the carcass, and an outer layer on the outer side in the radial direction of the inner layer, and the inner layer has a belt cord of an organic fiber. It is composed of two or more cut plies that are inclined at an angle of 35 to 60 degrees with respect to the tire equator and overlap inward and outward in the radial direction, and the outer layer is one or more long cords made of aromatic polyamide fiber with a topping rubber. While using a spiral wound ply formed by spirally winding the coated strip ply at a small angle to the tire equator, The outer layer, a radial tire for a motorcycle, characterized in that arranged 0.4 times and 0.7 times the width of the tread width, yet about the tire equator.