JPH04321402A - Radial tire for motor-cycle - Google Patents

Abstract

PURPOSE:To provide a tire for motor cycle, which is excellent in stability in high speed advance and in stability in high speed turn. CONSTITUTION:In a tire 1 composed of a carcass ply 3 in which organic fiber cords are arranged at an angle of 70 to 90 deg. with respect to the equator, and a direct belt layer 7 which is spirally arranged outside of the carcass ply 3, substantially parallel with the equator plane of the tire, the width of the above-mentioned belt layer is set to a value which is 0.7 to 1.0 times large as the tread widths B, and each of the cords of the belt layer is made of three aromatic polyamide fibers which are low-twisted at a range of 24 to 29T/10cm.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a pneumatic tire for motorcycles.

0002

2. Description of the Related Art Motorcycle tires are generally required to have turning stability, high-speed stability, and high-speed durability. For example, in Japanese Patent Application Laid-Open No. 1-109107, a tire aimed at providing these functions has a belt layer having a cord angle of 30 mm with respect to the tire circumferential direction.
It consists of two or more layers of cross belt plies with a cord angle of ~10° and two or more layers of spiral belt plies with a cord angle of substantially 0°, and at least one spiral belt ply is arranged between the carcass ply and the cross belt ply. I am proposing something that exists.

0003

Problems to be Solved by the Invention The above structure has the disadvantage that the structure of the belt layer is complicated, resulting in high cost, and that the fiber cords constituting the belt layer themselves tend to stretch. In other words, the number of fiber cords that make up the belt layer is usually 3.
Since a high twist of 0 to 35 T/10 cm is used, the tire itself has a large elongation, which causes tire growth during high-speed running, and has the drawback of poor high-speed stability.

[0004] The present invention was made in order to eliminate such conventional drawbacks, and an object of the present invention is to provide a motorcycle tire that is excellent in high-speed straight running stability and high-speed turning stability. be.

[0005]

[Means for Solving the Problems] The present invention provides a tread portion extending in an arch shape from the tire equatorial plane to both sides in the meridian direction, having a cross-sectional profile such that the tread width is the maximum width of the tire, and comprising at least one or more sheets of organic fibers. In a tire with a carcass ply in which the cords are arranged at an angle of 70 to 90 degrees with respect to the tire equator, and a belt layer arranged spirally on the outside of the carcass ply in a direction substantially parallel to the tire's equatorial plane, the width of the belt layer is the same as the tread. The cord of the belt layer is set to 0.7 to 1.0 times the width, and the cord of the belt layer is made of aromatic polyamide fiber cord and is formed of three low-twist cords in the range of 24 to 29 T/10 cm. be.

[0006] The belt layer is preferably wrapped directly around the outside of the carcass ply.

[0007]

[Function] In the above structure, the carcass ply is wrapped around a belt layer having a width of at least 0.7 times the tread width, and the cord of this belt layer is made of aromatic polyamide fiber and has a length of 24 to 29 T/10 cm. Because the tire is made of three low-twist strands, tire growth is restricted and excellent high-speed straight-line stability and high-speed cornering stability are achieved.

[0008]

[Embodiment] In FIG. 1, a tire 1 has a tread portion 2 and sidewalls 4 extending inward in the tire radial direction from both ends thereof, and a carcass ply 3 is provided inside the tread portion 2 and the sidewalls 4. Both ends of the carcass ply 3 are folded back around a bead portion 5 and a bead core 6 embedded in the inner end of the sidewall 4.

The tread portion 2 extends in an arch shape from the equatorial plane to both sides in the meridian direction, and the tread width B is a cross-sectional profile that is the maximum width of the tire 1, and the carcass ply 3
The tire is composed of at least one organic fiber cord arranged at an angle of 70 to 90 degrees with respect to the tire equator. A belt layer 7 is spirally wound directly on the outside of the carcass ply 3 substantially parallel to the equatorial plane of the tire, and the width of this belt layer 7 is 0.7 to 1.0 times the tread width B. The belt layer 7 is formed by three cords of aromatic polyamide fiber with a low twist in the range of 24 to 29 T/10 cm.

[0010] The width of the belt layer 7 is 70% of the tread width B.
If it is smaller than %, the rigidity of the tread portion 2 will decrease,
Since it causes uneven wear, it is necessary to set it to 70% or more. In addition, the cord is made of aromatic polyamide fiber with a low twist in the range of 24 to 29 T/10 cm, and is spirally wound substantially parallel to the equatorial plane of the tire to minimize elongation. Can be done.

FIG. 2 shows a cord made of aromatic polyamide fiber (
Curve 11 shows the load-elongation characteristics of Kevlar (trade name: Kevlar).
is Kevlar 1500/3 24.5T, curve 12 is Kevlar 1500/2 30T, curve 13 is Kevlar 1
500/3 35T, curve 14 is Kevlar 1500/
2 35T, curve 15 is 66 nylon 1680/4
23T are shown respectively. From these, the Kevlar low twist shown in curve 11 is 1500/3
It can be seen that 24.5T has less elongation under load and is excellent as a belt layer. Furthermore, by directly wrapping the belt layer 7 around the outside of the carcass ply 3, the tightening effect is effectively exerted.

Next, Table 1 shows the results of comparing the performance of the tire with the above structure with that of a tire with a conventional structure.

[0013]

[Table 1]

[0014] In Table 1 above, the cord material of the tire carcass is nylon in all samples, and the cord composition is 2/2.
1260d, the cord angle was 90°, and the number of cords was one. Furthermore, the cord material PA indicates aromatic polyamide. In addition, the above test results are based on tire size 1
A 70/60VR17 was used for the rear, and an actual vehicle feeling test was conducted. Note that a standard tire (120/70R17) was used as the front tire. As shown in Table 1 above, the test results show that the invention products of Sample 1 and Sample 2 exceed the acceptance standard of 110, and are clearly superior in both high-speed straight running stability and high-speed turning stability. It is being done.

[0015]

As explained above, the present invention provides a tire in which a belt layer is spirally arranged on the outside of the carcass ply substantially parallel to the equatorial plane of the tire, and the width of the belt layer is 0.7 of the tread width. The cord of the belt layer is a cord made of aromatic polyamide fiber with a low twist in the range of 24 to 29T/10cm.
It is made of real twist, and the growth of the tire is restricted by the cords of the belt layer, providing excellent high-speed straight running stability and high-speed turning stability.

[Brief explanation of drawings]

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

FIG. 2 is a characteristic diagram showing the load-elongation characteristics of a cord made of aromatic polyamide fiber.

[Explanation of symbols]

1 Tires 2 Tread part 3 Carcass ply 4 Side wall 7 Belt layer

Claims (2)

[Claims] Claim 1: The tread portion extends in an arch shape from the tire equator plane to both sides in the meridian direction, and has a cross-sectional profile such that the tread width is the maximum width of the tire, and at least one or more organic fiber cords are disposed at a distance of 70 mm from the tire equator. In a tire with carcass plies arranged at ~90 degrees and a belt layer arranged spirally on the outside of the carcass plies substantially parallel to the equatorial plane of the tire, the width of the belt layer is 0.7 to 1. The cord of the belt layer is a cord made of aromatic polyamide fiber and has a thickness of 24 to 29T/
A motorcycle tire characterized by being formed of three low twist strands with a length of 10 cm. 2. The motorcycle tire according to claim 1, wherein a belt layer is directly wound around the outside of the carcass ply.