JPH02128903A - Tire for motorcycle - Google Patents

Abstract

PURPOSE:To improve the durability of a tire without damaging control-safety by forming a belt-layer provided on the outside of a carcass by arranging an inner and an outer layer formed of Aramid fiber cord on both the inside and the outside with a middle layer formed of a nylon cord put between the inner and outer layers. CONSTITUTION:A tire 1 for a motor bicycle has a carcass 6 which extends from a tread part 5 through a side wall part 4 and turns on the circumference of a bead core 2 in a bead portion 3, and moreover a belt layer 7 arranged inside the tread part 5 and outside the carcass 6 in a radial direction. In the above-mentioned formation, the belt layer 7 is formed of a three layer plycord in which an inner layer 11, a middle layer 12 and an outer layer 13 are arranged in order from the carcass 6 toward a radial outside. The inner layer 11 and the outer layer 13 are formed of Aramid fiber cord respectively, and the middle layer 12 is formed of a nylon cord.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a motorcycle tire that can improve durability without impairing handling stability.

[Conventional technology]

Conventionally, the tread of a motorcycle tire is provided with a belt layer on the outside of the carcass in order to increase the rigidity of the tread. This belt layer a is formed by overlapping two belt layers b and c, as shown in FIG. 3, for example, and
This belt brace b1C is formed using a cord made of aramid fiber. Aramid fiber cords have many advantages compared to nylon fiber cords, such as being lighter in weight with the same rigidity, high-speed durability, and excellent cornering performance.

[Problem that the invention seeks to solve]

However, belt bridles made of aramid fiber cords have lower adhesive strength than those of nylon fiber cords, and as a result, separation tends to occur at the ends of the belt layer, resulting in damage to the shoulder parts and other problems. The elasticity was about 1/3 that of nylon.

In the present invention, the belt layer is formed by three layers of braai, and the belt layer is provided with an inner layer and an outer layer made of aramid fiber cords on the inner and outer sides of the intermediate layer using an intermediate nylon cord. The basic objective is to provide a motorcycle tire that can improve durability without compromising handling stability.

[Means to solve the problem]

In order to achieve the above object, the motorcycle tire of the present invention includes a carcass that passes from the trend part to the sidewall part and folds around the bead core of the repeat part, and a carcass that is located inside the tread part and outside in the radial direction of the carcass. Moreover, the belt layer includes an inner layer using an aramid fiber cord, an intermediate layer using a nylon cord located outside the inner layer, and an outer layer using an aramid fiber cord located outside the intermediate layer. This is a motorcycle tire.

[Effect]

There are three belt layers, with an intermediate layer made of nylon cord sandwiched between them, and an inner layer and an outer layer made of aramid fibers placed on the inside and outside of the intermediate layer, so the ends of the inner layer and outer layer made of aramid fibers are secured by the highly adhesive nylon. This enables strong bonding and prevents the occurrence of peeling that tends to occur from the ends of the belt layer, and by preventing damage to the shoulder portion, the durability of the tire can be improved without impairing handling stability.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In the figures, the motorcycle tire 1 of the present invention has bead portions 3.3 on both sides through which the bead core 2 passes, and side surfaces extending outward in the tire radial direction from the bead portions 3. It has a wall part 4 and a tread part 5 joining the upper end of the wall part 4, and the bead core 2 of the repeat part 3 is passed from the tread part 5 to the side wall part 4.
The belt layer 7 is provided inside the tread portion 5 and on the outside in the radial direction of the carcass.

In this embodiment, the carcass 5 is made of a single ply and is made by twisting two 1260 denier nylon wires to form a cord, and the cord is 60 to 90'' in the direction of the tire equator C. It is a radial structure arranged at an angle of .

The belt layer 7 includes three layers arranged in the order radially outward from the carcass 5: an inner layer 11, a middle layer 1112, and an outer layer 13.
Consisting of layers of braai cord, each layer 11.12.1
3 are joined together and integrated.

In this embodiment, the inner layer 11 is made by twisting two wires made of aramid resin of 1500 denier to form a cord body, and arranging the cord body at an angle of 65″ to 85° with respect to the tire equator. This is a belt cord using an aramid resin cord.

The intermediate layer 12 is a belt cord using a nylon cord formed by arranging two cords of twisted 1260 denier nylon wires in parallel.

The outer layer 13 is a belt ply using a cord made of aramid resin between the inner layer and the track, and in this embodiment, the inclination of the cord of the outer layer 13 is opposite to the inclination of the cord of the inner layer 11. They are arranged at an angle of 65 to 85 degrees.

In this embodiment, the belt layer 7 has a width in the axial direction of the tire, the intermediate layer 12 has a wider width than the inner layer 11, and the outer layer 13 has a wider width than the intermediate layer 112, that is, the width gradually increases toward the outside. It is formed like this.

By arranging in this way, the inner 7111 and the outer 11
13 can be firmly fixed by the intermediate layer 12 made of nylon cord, and separation from the ends can be prevented.

Incidentally, the belt layer 7 can also be formed so that the width thereof gradually increases from the outer layer 13 toward the inner layer 11, as shown in FIG. However, expanding outward as shown in FIG. 1 is more effective in improving durability because the outer layer 13 can hold down the intermediate layer 12 and inner layer 11.

(Specific Example) A tire having a tire size of 140/60 R18 and a structure shown in FIG. 2 was prototyped with the specifications shown in Table 1, and a durability test was conducted. Tires with conventional specifications were also tested at the same time for comparison.

The test is based on the following conditions.

1) Durability test The tests were conducted indoors using a drum running test machine.

The test load was 380 kgf, the internal pressure was 3 kgf/cd, and the speed was $51 u*/Hr, and the tire was judged based on the travel distance until it broke.

2) A load of 250 kg f was applied using a high-speed durability tester in a high-speed durability test room.
, the internal pressure is 3 kgf/cd, the room temperature is 38°C, the initial velocity is 1851 ue/)Ir every 30 m1n [3k
Judgment was made by step-up m/Hr and the travel distance until failure.

3) Driving stability It was installed in an actual vehicle and judged based on the driver's feeling.

As shown in Table 1, the test results confirmed that the durability of the examples was significantly improved compared to the comparative examples, and the handling stability was not impaired.

〔Effect of the invention〕

In this way, the belt layer is sandwiched between an intermediate layer made of nylon cord and an inner layer and an intermediate layer made of aramid fiber cords are placed on the inside and outside of the intermediate layer, which improves durability without compromising handling stability. can.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention, FIG. 2 is a sectional view showing another example of a belt layer, and FIG. 3 is a sectional view showing a conventional technique. 2--Bead core, 3--Bead section, 4-Side wall section, 5--Tread section, 6--Carcass, 7--Belt layer, 11--Inner layer,
12...-Middle layer, 13... Outer layer, C-... Tire equator. Patent applicant: Sumitomo Rubber Industries, Ltd. Representative patent attorney: Tadashi Naemura

Claims (1)

[Claims] 1 A carcass that passes from the tread part through the sidewall part and folds around the bead core of the bead part, an inner layer located inside the tread part and radially outside the carcass and made of aramid fiber cord, and located outside the inner layer. A motorcycle tire comprising a belt layer comprising an intermediate layer using a nylon cord and an outer layer located outside the intermediate layer and using an aramid fiber cord.