JPH04365601A - Tire for motorcycle - Google Patents

Abstract

PURPOSE:To secure traveling stability in the straight advance and turn during the high speed traveling by inclining a carcass layer and a belt layer each of which is formed from two-three plies, by nearly in the intermediate part between the radial arrangement and bias arrangement and in the nearly equal angle to radial tire with respect to the tire equator. CONSTITUTION:A carcass layer 6 and a belt layer 7 are formed of carcass plies 6A and 6B and belt plies 7A-7C. Each carcass ply 6A, 6B consists of a carcass belt consisting of organic fibers which are inclined in 40-70 deg. with respect to a tire equator C, and at the same time, respective belt plies 7A-7C consist of a belt cord inclined 11-25 deg.. Further, the height Hb from the bead bottom surface 15 at the outer edge in the radial direction of a bead apex 9 is set lower than the conventional value, i.e., to 0.15-0.6 of the tire sectional height, and further, a side wall rubber layer 14 made of the rubber having the lower hardness than that of a tread part 2 formed between a bead bottom surface 15 and the tread edge on the outer side in the tire axis direction of the carcass 6 of a side wall part 3.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motorcycle tire that can improve running stability, handling stability, and riding comfort.

0002

2. Description of the Related Art When turning a motorcycle, unlike a four-wheeled vehicle, a motorcycle tilts its body to make a turn, that is, has a camber angle, which is characteristic of a two-wheeled vehicle. In order to maintain riding comfort and maintain camber thrust for stable running even when running on an incline, motorcycle tires have their carcass held at an angle of 30 to 35 degrees with respect to the tire equator. X tilted at an angle of
It has a ply structure, and the belt layer has a belt cord of 11
By setting the angle to ~25°, it has been attempted to ensure running stability when traveling straight and when turning.

0003

[Problem to be solved by the invention] However, in recent years, with the development of expressway networks, the speeds of motorcycles have increased, and even tires for motorcycles have been required to further stabilize straight-line performance and turning performance during high-speed driving. It has become requested. In order to meet this demand, we have increased the number of carcass plies in motorcycle tires, lowered the inclination of each cord of the carcass and belt layer to the tire equator to 24 to 28 degrees, and further increased the thickness of the rubber in the tread. Attempts were made to improve running stability using methods such as increasing the number of vehicles. However, the structure described above lacks steering stability due to the increased spring constant of the tire.
The ride comfort is also poor.

On the other hand, when the carcass is arranged in a radial manner, running stability is improved, but the rigidity of the sidewall portion is insufficient, resulting in a decrease in handling stability and riding comfort.

[0005] The present invention improves running stability when going straight and turning, and also improves steering stability by making the belt layer have a cord arrangement similar to that of a radial tire and the carcass having a smaller cord inclination than that of a radial tire. The aim is to provide motorcycle tires that can improve riding comfort.

[0006]

[Means for Solving the Problems] The present invention provides two or three carcass plies which are integrally provided with a winding part that is folded back at the bead core on the main body part extending from the tread part through the sidewall part to the bead core of the bead part. A carcass consisting of;
A belt layer consisting of two or three belt plies arranged inside the tread portion and radially outward of the carcass, and a hard material extending radially outward from the bead core between the main body portion and the winding portion of the carcass. and a bead apex made of rubber, the carcass ply ply comprising an organic fiber carcass cord inclined at an angle of 40 to 70 degrees with respect to the tire equator, and a belt ply having an angle of 11 to 70 degrees with respect to the tire equator. A belt bottom surface made of organic fibers inclined at an angle of 25° is provided, and the height of the radially outer end of the bead apex from the bead base is 0.15 times or more and 0.6 times the cross-sectional height of the tire. In addition, a sidewall rubber layer made of rubber having a hardness lower than that of the rubber of the tread portion is provided on the outside of the carcass in the tire axial direction in the sidewall portion and between the bead bottom surface and the tread edge. It is a motorcycle tire.

[0007]

[Operation] Both the carcass and the belt layer are formed of two or three plies. This increases the rigidity of the tread, sidewalls, and beads.
By increasing the camber thrust, turning performance is improved, straight-line performance is improved, and driving stability is significantly increased.

The inclination angle of the belt cord of the belt layer is set to 11 to 25 degrees with respect to the tire equator, which is approximately the same as that of a radial tire, while the inclination of the carcass cord with respect to the tire equator is determined between the radial arrangement and the bias arrangement. By setting the inclination angle to approximately the middle, the rigidity of each part of the tire, especially the sidewall part, is softened.
The camber thrust can be substantially maintained, driving stability can be maintained, and handling stability and ride comfort can be improved.

Moreover, the height of the bead apex is 0.15 to 0.6 times the cross-sectional height of the tire, which is lower than that of conventional tires, and the rubber hardness of the sidewall rubber layer is also lower than that of the rubber in the tread. As a result, the spring constant of the tire can be reduced without reducing the rigidity of the tread portion, and handling stability and ride comfort can be improved without reducing running stability.

[0010] As described above, in the present invention, the above-mentioned configurations are organically integrated, thereby improving running stability during straight running and turning, and at the same time improving steering stability and riding comfort.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIGS. 1 and 2, a radial tire 1 for a motorcycle includes a tread portion 2, a sidewall portion 3 extending from both ends of the tread portion 3 inward in the tire radial direction, and a bead located at the inner end of the sidewall portion 3 in the tire radial direction. part 4, passing from the tread part 2 through the sidewall part 3,
A carcass 6 is provided on a main body part 6a extending in the bead part 4, and a carcass 6 is provided with a winding part 6b for winding and folding the bead core 5 from the inner side in the axial direction to the outer side of the tire, and the carcass 6 is disposed inside the tread part 2 and on the outer side in the radial direction of the carcass 6. A belt layer 7 is provided. Moreover, the winding part 6b and the main body part 6a of the carcass 6
A bead apex 9 with a triangular cross section extending outward in the tire radial direction is provided between the tire and the tire.

The carcass 5 includes two or three carcass plies 6A, in this embodiment two carcass plies 6A, each having a carcass cord 11 inclined at an angle of 40 to 70° with respect to the tire equator C.
, 6B, and the carcass cord 11 is an organic fiber cord such as nylon, rayon, polyester, or aromatic polyamide. In addition, two pieces of the carcass ply 6A
, 6B are arranged such that the carcass cords 11, 11 intersect with each other.

The belt layer 7 includes two or three belt plies 7A, 7B in this embodiment, each having a belt cord 12 inclined at an angle of 11 to 25 degrees with respect to the tire equator C.
7C, and the belt cord 12 is an organic fiber cord such as nylon, rayon, polyester, or aromatic polyamide. Note that the three belt plies 7A and 7B
, 7C are arranged in such a manner that the belt cords 12, 12 cross each other between adjacent belt plies as shown in FIG.

Therefore, each cord 11 of each carcass ply 6A, 6B and each belt ply 7A, 7B, 7C
, 11, 12, 12, 12 intersect with each other to form a plurality of force triangles as shown in FIG. 2, thereby significantly improving the rigidity of the tread portion 2.

A tread rubber 13 is disposed in the tread portion 2 between the outward facing surface of the belt layer 7 and the tread surface 2a. In this embodiment, the rubber 13 of the tread portion is formed of a relatively hard rubber having a hardness of 60 to 66 degrees of JISA hardness and a 100% modulus of 30 to 40 kg/cm2.

Bead Apex 9 has a JISA hardness of 7.
The height Hb from the bead bottom surface 15 of the outer end in the radial direction is equal to 0 of the tire cross-sectional height Ht, which is the distance from the bead bottom surface 15 to the outermost radial direction of the tread portion 2. .15 times or more and 0.6 times or less. If the height Hb of the bead apex 9 is less than 0.15 times the cross-sectional height Hb of the tire, the bead portion 4 is likely to buckle during running, especially when turning, resulting in a decrease in steering stability. On the other hand, if it exceeds 0.6 times, the rigidity of the sidewall portion 3 will be excessive and the riding comfort will be poor.

[0017] The sidewall portion 3 also has a bead bottom surface 15 and a tread edge E on the outside of the carcass 6 in the tire axial direction.
A sidewall rubber layer 14 made of rubber having a composition different from that of the rubber 13 of the tread portion is formed between the tread portion and the tread portion. In this example, the sidewall rubber layer has a hardness of JIS
The A hardness is 55 to 60 degrees or 100% modulus is 20 to 25 kg/cm2, and therefore, it is formed of a rubber having a lower hardness than the rubber 13 of the tread portion.

Incidentally, in conventional motorcycle tires, the rubber of the sidewall rubber layer is made of the same rubber as the rubber 13 of the tread portion, and the rubber on the outside of the tread portion 2 is directed toward the sidewall portion 3. However, as mentioned above, the sidewall rubber layer 14 was provided and the hardness of the sidewall rubber layer 14 was adjusted to match the hardness of the rubber 13 of the tread portion.
By making the hardness lower than the hardness of As a result, the spring constant of the tire can be lowered and ride comfort and handling stability can be improved.

Furthermore, the thickness T of the sidewall rubber layer 14 is 5.0 to 7.0 mm in the conventional case when the tire size is 160/70-17 at the maximum width position of the carcass. On the other hand, in this example, the thickness is 2.0 mm to 5.0 mm, which is approximately 2.0 to 3.0 mm thinner than the conventional one, in order to further improve riding comfort. .

[0020]

[Specific example] The tire size is 160/70-17,
A tire (Example) having the configuration shown in FIG. 1 was prototyped with the specifications shown in Table 1, and its performance was tested. A tire with a conventional configuration (comparative example) was also tested and its performance was compared.

[0021] The test was carried out by equipping an actual vehicle with a sample tire, driving it on a paved road, and evaluating each item based on the feeling of the test driver.
It is expressed as an index. The larger the value, the better.

[0022]

[Table 1]

[0023] As a result of the test, it was confirmed that the example was good in all of the items, and could improve both running performance, handling stability, and riding comfort.

[0024]

As described above, the high speed heavy load tire of the present invention has a carcass consisting of two to three carcass plies with the carcass cord inclined at an angle of 40 to 70 degrees, and a belt cord inclined at an angle of 11 to 25 degrees. The main idea is to provide a belt layer consisting of two or three belt plies inclined at an angle of , and a sidewall rubber layer made of rubber having a lower hardness than the rubber of the tread portion on the outside of the sidewall portion. Therefore, it is possible to improve running stability when going straight and turning, and to improve steering stability and riding comfort.

[Brief explanation of drawings]

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

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

[Explanation of symbols]

2 Tread part 3 Sidewall part 4 Bead part 5 Bead core 6 Carcass 6a Main body part 6b Winding part 6A, 6B Carcass ply 7 Belt layer 7A, 7B, 7C belt ply 9 Bead Apex 11 Carcass cord 12 Belt cord 13 Rubber of tread part 14 Sidewall rubber layer 15 Bottom of bead C Tire equator E Tread edge

Claims (1)

[Claims] [Claim 1] A carcass consisting of two or three carcass plies, which is integrally provided with a winding part that is folded back at the bead core on the main body part extending from the tread part through the sidewall part to the bead core of the bead part, and the tread part. A belt layer consisting of two or three belt plies arranged inside and radially outward of the carcass, and a hard rubber extending radially outward from the bead core between the main body part and the winding part of the carcass. the carcass ply comprises an organic fiber carcass cord inclined at an angle of 40 to 70 degrees with respect to the tire equator, and the belt ply comprises an organic fiber carcass cord inclined at an angle of 11 to 70 degrees with respect to the tire equator
A belt cord made of organic fiber is provided that is inclined at an angle of 25 degrees, and the height of the radially outer end of the bead apex from the bottom surface of the bead is 0.1 of the cross-sectional height of the tire.
5 times or more and 0.6 times or less, and in addition, the side wall portion is made of rubber having a hardness lower than that of the rubber of the tread portion on the outside in the tire axial direction of the carcass and between the bead bottom surface and the tread edge. A motorcycle tire with a wall rubber layer.