JP3108531B2 - Motorcycle tires - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention suppresses the growth of the outer diameter of a tire due to high-speed rotation, thereby preventing heat generation in a tread portion, improving high-speed durability, and inwardly moving the tread portion in a radial direction during straight running. The present invention relates to a tire for a motorcycle capable of improving the ground contact property by reducing the bending stiffness of the tire and improving the steering stability by reducing the cornering power.

[0002]

2. Description of the Related Art In recent years, the technical development of motorcycles has been remarkably progressed, and motorcycles having a maximum speed exceeding 300 km / H have been emerging. Further, in such a tire mounted on a motorcycle, there is a demand for a large improvement in high-speed durability and an improvement in steering stability.

[0003] Conventionally, motorcycle tires have a carcass and belt layer cords crossed in the same manner as four-wheel tires to increase the rigidity of the tread portion in order to enhance the high-speed performance. There are some such as a nylon band wound around the outside of the layer, but with such a structure, the weight of the tire increases and the heat generation of the tread part is large due to the increase of the load due to high speed running and the durability is increased. There is a problem of inferiority.

[0004] In order to solve one end of such a problem, a belt cord is spirally wound to form a belt ply. However, in such a structure of the belt layer, the center of a tread portion is formed. In the region, the fracture strength is inferior, and the impact resistance of the tire is reduced.On the other hand, in the shoulder region, it is necessary to further increase the compression fatigue resistance in relation to the bank angle. .

According to the present invention, the outer diameter growth of a tire during high-speed running is based on the fact that the belt cord forming the belt layer is formed of organic fibers and the rigidity of the belt layer in the central region is made smaller than that of the shoulder region. It is an object of the present invention to provide a tire for a motorcycle that can improve high-speed durability, improve ground contact performance, and improve steering stability by suppressing the occurrence of heat in the tread portion.

[0006]

According to the present invention, there is provided a carcass comprising at least one carcass ply which is folded from a tread portion through a side wall portion and around a bead core of a bead portion, a carcass ply in the radial direction outside the carcass and inside the tread portion. A motorcycle layer provided with a belt layer comprising one or more belt plies disposed on one side, wherein the carcass ply is formed by forming a carcass cord using an organic fiber at an angle of 60 to 90 degrees with respect to the tire equator. And the belt ply spirally winds a belt cord rubberized to a cord having a tensile elastic modulus of 600 kg / mm ² or more substantially parallel to the tire equator, and attaches the tread portion to the tread portion. The tread width (T is the distance between the outer edges in the tire axial direction.
W) is a central region (M) located inside the point (P) with the point (P) separating the tire equator (C) in the tire axial direction from the tire equator (C) by a distance of 0.25 times or more and 0.35 times or less. )
And a shoulder region (S) which is a region outside the point (P), and the belt ply determines the tensile modulus of the belt cord in the central region (M) as compared to the shoulder region (S). Is small, and the ratio is 0.1.
A tire for a motorcycle, characterized in that the number is not less than 8 and not more than 0.9.

[0007]

[Function] The belt ply has a tensile modulus of elasticity of 600 kg / mm ^2.
Since the belt is formed by using the cord made of the organic fiber, the strength of the belt layer is increased as compared with the conventional cord using the cord made of nylon or polyester fiber.

Further, since the belt cord is spirally wound substantially parallel to the tire equator, the growth of the outer diameter of the tire during high-speed running can be suppressed.

In addition, the belt cord of the belt layer has a tensile modulus of the belt cord in the central region M smaller than that of the belt cord in the shoulder region S and a ratio of 0.8 to 0.9 times. Central area M
In this case, the bending rigidity of the tread is reduced and the contact property is improved. On the other hand, the cornering power is reduced, thereby improving the steering stability when traveling straight. On the other hand, since the bending rigidity in the shoulder region is larger than that in the central region, the compression fatigue resistance is increased, and the growth of the outer diameter can be further suppressed, and the heat generation in the tread portion is prevented and the high-speed durability is improved. Further, camber stiffness is increased, and turning performance is improved.

When the ratio of the tensile elastic modulus is less than 0.8, the rigidity in the shoulder region S becomes large and the steering stability during turning decreases, while when it exceeds 0.9, the above-mentioned improvements in performance are achieved. I can't get it.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. In the figure, the motorcycle tire 1 of the present invention has bead portions 3 on both sides through which a bead core 2 passes, and a sidewall portion 4 extending outward in the tire radial direction from the bead portion.
A carcass 6 having a tread portion 5 that joins the upper end thereof, and a carcass 6 that is folded from the tread portion 5 through the sidewall portion 4 around the bead core 2 of the bead portion 3;
And a belt layer 7 arranged radially outward of the inside of the tread portion 5.

In the present embodiment, the carcass 6 is formed of a single carcass ply and two strands of 1500 denier polyester fiber are twisted to form a cord. Radial or semi-radial structures arranged at an angle of 90 °.

In this embodiment, the belt layer 7 is composed of a single belt ply 11 disposed radially outside the carcass 6.

The belt ply 11 has a tensile modulus of 600
A belt cord having a high elasticity of kg / mm ² or more and made of organic fiber such as aromatic polyamide or steel or the like is spirally wound substantially parallel to the tire equator C. When the belt layer 7 is composed of two plies, the outer belt plies disposed radially outside of the belt plies in the tire radial direction have substantially the same width as the belt plies and are made of organic fibers of substantially the same type as the belt plies. The belt cord is formed in a spiral shape opposite to the belt ply 11 and the tire equator C
And wound in parallel.

In the belt ply 11, the tensile modulus of the belt cord is different between the inner side and the outer side in the tire axial direction with respect to points P, which form boundary points.

The point P is located on the belt layer 7 which separates a distance L from the tire equator C by a distance L not less than 0.15 times and not more than 0.25 the tread width TW, which is the distance between the tread outer edges E and E in the tire axial direction. Located in. The belt layer 7 defines the tire equator C side from the point P as a boundary, that is, an inner central region M, and an outer edge E side from the point P, that is, an outer side as a shoulder region S.

In this embodiment, the belt cord has a tensile modulus of 600 kg / cm ^{2 in} both the central region M and the shoulder region S.
The above cord is formed by being embedded in the rubber width, and the tensile elastic modulus of the cord and the embedded rubber is made smaller in the central region M than in the shoulder region S, and the ratio is set to 0.8 or more and 0 0.9 or less.

When the vehicle is traveling straight, the vehicle is mainly grounded in the central area M. Therefore, in order to improve the contact property of the tire, the inward bending rigidity of the belt layer 7 in the central region M is reduced, and as a result, the cornering power when the slip angle is small is reduced, and the straight running stability is improved.

On the other hand, in the shoulder region S, since the elastic modulus is larger than that in the central region M, the camber thrust increases in a large range of the camber angle of 30 to 45 °.

Further, in this embodiment, the belt layer 7 is
The 100% modulus of the rubber covering the belt cord is different between the central region M and the shoulder region S. In the central region M, the modulus of the rubber 100% is 40 kg / cm ² or more and 50 kg / cm ² or less, and the 100% modulus of the central region M is smaller in the central region M than in the shoulder region S. By doing
The inward bending rigidity of the belt layer 7 in the central region M is further reduced, and the straight running performance is further improved. On the other hand, in the shoulder region S, the camber thrust is further increased and the turning running stability can be further improved.

[0021]

EXAMPLE A tire having a tire size of 160 / 60R17 having the configuration shown in FIG. 1 and having the specifications shown in Table 1 was prototyped and tested under an air pressure of 2.9 kgf / cm ² under a load of 260 kg. For comparison, a tire other than the configuration of the present invention (Comparative Examples 1 to 5) was also prototyped and a comparative test was performed. Each test was performed under the following conditions.

High-speed endurance test Starting from a speed of 80 km / H using a drum running test machine with a smooth surface, increasing the distance by 10 km / H every 24 hours of running to determine the running distance until failure, and Comparative Example 1
Is indicated by an index with the value of 100 as 100. The larger the numerical value, the better, and 110 or more is a pass.

Tire Strength A tire strength was tested according to a test method specified in JIS K6301, and the value of Comparative Example 1 was set to 100 and indicated as an index. The larger the numerical value, the better, and 110 or more is a pass.

Straight running stability, cornering stability Mounted on a real vehicle, the straight road of the test road is 240km / H
Further, the vehicle was run on a curved road having a radius of 400 m at a speed of 180 km / H, evaluated by the feeling of a test driver, and indicated by an index with 1 in Comparative Example being 100. The higher the value, the better.

[0025]

[Table 1]

[0026]

As described above, in the motorcycle tire of the present invention, the belt layer is divided into a central region and a shoulder region, and the elastic modulus in the central region is 0.8 to 0.1 of the shoulder region.
The gist is to increase the contact area by 9 times, so that the contact area is improved and the steering stability is improved in the central area, while the compression fatigue resistance is increased in the shoulder area, so that the growth of the outer diameter of the tread can be suppressed and the heat generation can be reduced. Prevent and enhance high-speed durability.

[Brief description of the drawings]

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

FIG. 2 is a developed plan view showing the arrangement of the cords of the carcass and the belt layer.

[Explanation of symbols]

 2 Bead core 3 Bead section 4 Side wall section 5 Tread section 6 Carcass 7 Belt layer 9 Carcass ply 10 Belt ply C Tire equator E Outer edge M Central area S Shoulder area

Claims (2)

(57) [Claims] 1. A carcass comprising at least one carcass ply that is folded from a tread portion through a sidewall portion and around a bead core of a bead portion, and at least one carcass disposed radially outside the carcass and inside a tread portion. A motorcycle layer provided with a belt layer composed of a belt ply of (a), wherein the carcass ply has carcass cords using organic fibers arranged at an angle of 60 to 90 degrees with respect to the tire equator; Is the tensile modulus of elasticity 600 kg / mm ²
A belt cord rubberized to the above cord is spirally wound substantially parallel to the tire equator, and the tread portion has a tread width (TW) which is a distance between outer edges of the tread portion in a tire axial direction. 0.25 times or more.
A center region (M) located inside the point (P) and a point outside the point (P) with the point (P) separated from the tire equator (C) by 35 times or less in the tire axial direction as a base point. The belt ply is virtually divided into a shoulder region (S), and the belt ply has a tensile modulus of the belt cord that is smaller in the central region (M) than in the shoulder region (S) and the ratio is 0.8. A tire for a motorcycle characterized by being not less than 0.9 and not more than 0.9. 2. The belt ply according to claim 1, wherein the belt ply is in the central region
In the above, the 100% modulus of the rubber in which the belt cord is embedded is set to 40 kg / cm ² or more and 50 kg / cm ² or less, and the 100% modulus of the rubber is smaller than the shoulder region (S) and the ratio is set to 0.8. Above and 0.
The motorcycle tire according to claim 1, wherein the number is 9 or less.