JP3053287B2 - Radial tires for motorcycles - Google Patents

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 which excels in straight running performance and has improved turning performance when turning in an inclined state.

[0002]

2. Description of the Related Art In a tire for a motorcycle, since the vehicle body runs with a large inclination when turning, it is necessary to maintain running stability even during this turning, and the tire has a large lateral rigidity. That is, tires having a cross-ply structure have been widely used. However, in recent years, as the expressway network has been enhanced and the performance of the vehicle body has been improved, the performance of motorcycle tires has been required to be improved for high-speed running.

[0003] In response to such a demand for high speed, tires having a radial structure have appeared even for motorcycles.
In the radial tire for a motorcycle, for example, as proposed by the applicant in Japanese Patent Application No. 2-103305, the entire belt layer is formed by ply pieces obtained by spirally winding a small band-shaped ply.

[0004] As a result, the ply is continuous in the circumferential direction as compared with the conventional structure in which the cut plies are joined to each other, so that the traveling performance when traveling straight, especially at high speed traveling, is dramatically improved. is there.

[0005]

However, the belt layer formed by the spiral winding of the belt-like ply is inferior in lateral rigidity and inability to maintain a high camber thrust at the time of turning while leaning the vehicle body. There is a problem.

In order to increase the lateral rigidity of the tire, it has been proposed to increase the number of carcass plies and to add a reinforcing layer to the side wall portion. However, this increases the lateral rigidity but significantly increases the tire weight. By
It is not preferable because the fuel cost increases as the material cost increases.

The inventor of the present invention has found that by forming the belt layer in the most suitable configuration in the central region and in the shoulder region, it is possible to satisfy both straight traveling performance and turning traveling performance, and completed the present invention. is there.

The present invention is based on the principle that the belt layer is formed by a ply piece formed by spiral winding of a belt-like ply in the central region, and is formed by a sheet-like cut ply in the shoulder region. The purpose of the present invention is to provide a radial tire for a motorcycle having excellent running performance and improved turning performance.

[0009]

SUMMARY OF THE INVENTION The present invention comprises a main body extending from a tread portion through a sidewall portion to a bead portion, a winding portion connected to the main body portion and turned around a bead core of the bead portion, and a tire equator. And a carcass using one or more carcass plies having a carcass cord inclined at an angle of 70 to 90 ° with respect to the tire axial direction while being arranged inside the tread portion and radially outside the carcass. The width is at least 0.88 times the tread width and 0.92
A radial tire for a motorcycle, comprising a belt layer having a width of not more than twice the width of the tread width, wherein the belt layer has a distance of not less than 0.2 times and not more than 0.35 times the tread width on both sides around the tire equator. A central region located inside and two shoulder regions located outside the dividing point in the tire axial direction. The central region is provided with a topping rubber belt cord made of an organic fiber having an elastic modulus of 600 kg / mm ² or more. The belt region is formed of one or more ply pieces spirally wound at a small angle with respect to the tire equator at a small angle with respect to the tire equator, while the shoulder region is formed of a belt cord made of organic fibers. A motorcycle in which sheet-like cut plies, which are inclined at an angle of 10 ° or more and 40 ° or less, are superposed in two layers inward and outward in the radial direction. It is a radial tire use.

[0010] In the shoulder region of the belt layer, two cut plies are formed by overlapping inside and outside, and one cut ply is formed as a bent ply bent at the belt end side. Is also good.

[0011]

The carcass has a carcass cord of 70 to 90.
The radial arrangement inclined at an angle reduces the rigidity of the tire as a whole, and improves high-speed running performance when traveling straight.

The belt layer consists of ply pieces formed by spiral winding of a belt-like ply in the central region.
The ply piece thus formed does not have a seam of the ply in the circumferential direction unlike the cut ply, and is continuous in the circumferential direction. Therefore, the straight traveling property is remarkably enhanced, and high-speed traveling is possible. . Moreover, since the belt-like ply is inclined at a small angle with respect to the tire equator, no one-sided flow during traveling is recognized, and steering stability can be improved.

The belt-like ply has an elastic modulus of 600 kg /
Because it is formed by organic fiber cord of mm ² or more,
Tire weight can be reduced while maintaining the rigidity of the tread portion as compared with a conventional belt ply using a steel cord.

On the other hand, in the shoulder area, the cut plies are superposed in two layers, and the belt cord is
Since it is arranged in a direction intersecting the carcass cord at 0 to 40 °, the tag effect is exhibited and the rigidity of the tread portion in the shoulder region is significantly increased. As a result, even when the vehicle is running with the vehicle body tilted, such as when turning, running stability can be maintained without occurrence of hip breakage, and turning performance can be improved.

If the width of the belt layer is less than 0.88 times the width of the tread, the running surface of the tread portion protrudes from the belt layer during incline running to reduce the turning performance. The end portion is too close to the sidewall outer wall, and the bending of the tire is reduced, so that the riding comfort is reduced.

If the position of the dividing point between the central region and the shoulder region from the equator of the tire is less than 0.2 times the tread width, the rigidity of the tread portion increases and the stability during straight running decreases, If it becomes larger than 0.35 times, the turning traveling stability is impaired by contacting the ply piece formed by the band-shaped ply with the ground even during the inclined traveling.

As described above, according to the present invention, since the above-mentioned components are organically integrated, the straight running performance is excellent and the running performance can be improved even when the vehicle is turning while running in an inclined state. .

[0018]

An embodiment of the present invention will be described below with reference to the drawings. In the figure, the radial tire 1 for a motorcycle has a tread width TW, which is the distance between the tread edges E of the tread portion 2 in the tire axial direction, and the tread surface 2A is centered on the tire equator C. The tire is formed as a motorcycle tire having an arcuate shape and has a tread portion 2, sidewall portions 3 extending inward in the tire radial direction from both ends thereof, and a tire radially inner end of the sidewall portion 3. And a pair of bead portions 4, 4.
Further, the radial tire 1 for a motorcycle includes the tread portion 2.
A carcass 6 having a folded portion 6b for folding a bead core 5 of the bead portion 4 from the inside in the tire axial direction to the outside in a body portion 6a extending from the tire to the bead portion 4 through the sidewall portion 3; A belt layer 7 disposed inside and radially outside of the carcass 6, and a main body 6 of the carcass 6 outside of the bead core 5 in the tire radial direction and
A bead apex 8 made of hard rubber is set up between a and the folded portion 6b.

The carcass 6 comprises at least one carcass ply having a radial arrangement of carcass cords inclined at an angle of 70 to 90 ° with respect to the tire equator C, and in this embodiment, one carcass ply. For example, an organic fiber cord such as nylon, polyester, or aromatic polyamide fiber is used. In this embodiment, the carcass 6 has a folded height HC, which is the height of the folded portion 6b from the bead bottom surface 4a, and the bead bottom surface 4a of the tread edge E.
0.2 to 0.8 of tread edge height HE which is the distance from
Set to double.

The belt layer 7 has a width BW in the tire axial direction of 0.88 times or more of the tread width TW and 0.9% or more.
It is set to a range of twice or less. The belt layer 7 has a center region M interposed between the partition points P, P and a tire axis of the partition point P, which are disposed on both sides of the tire equator C in the tire axial direction. 2 located on the outside in the direction
Are divided into two shoulder regions S, S. The section point P is set so that the distance PL starting from the tire equator C is in a range of 0.2 times or more and 0.35 times or less of the tread width TW.

The central region M is composed of ply pieces 9 formed by spirally winding a small band-shaped ply 10.
As shown in FIG. 3, the belt-like ply 10 has one belt cord or a plurality of belt cords arranged in parallel.
Is embedded in a topping rubber 12, and a high elastic organic fiber cord having an elastic modulus of 600 kg / mm ² or more is used as the belt cord 11. As the high-elasticity cord, an aromatic polyamide fiber having substantially the same tensile strength as steel and weighing less than steel can be suitably used.

[0022] The belt-shaped ply 10, the starting point H1 position separating the small dimension of the axially outside from the one segment point P
In FIG. 1, spiral winding is performed at a small angle of 5 ° or less with respect to the tire equator C from the left to the right and beyond the tire equator to the end point H2, which is slightly smaller than the other division point P with respect to the tire equator C. The ply pieces 9 can be formed. Therefore, the ply piece 9
Has protruding portions 9a, 9a extending outward in the tire axial direction beyond the other dividing points P, P. Further, in the present embodiment, as shown in FIG. 4, when winding the band-shaped ply 10, the vicinity of the opposing side edges 10a, 10a of the band-shaped ply 10 are wrapped around each other and wound to prevent the band-shaped ply 10 from being loosened. ing. The central region M may be formed of two or more ply pieces 9 according to the above-described configuration, that is, two or more helical windings of the belt-like ply 10 as a plurality of layers.

The shoulder region S is formed by the cut ply 14 superposed on two layers. In the present example, it is composed of two cut plies 14. The cut ply 14 is a sheet body in which a belt cord 15 made of an organic fiber such as nylon, polyester, or aramid is arranged at an angle of 10 ° or more and 40 ° or less with respect to the tire equator C, and overlaps in the present embodiment. 2
The cut plies 14, 14 have their belt cords 15
Are tilted in opposite directions. Further, in this embodiment, the protruding portion 9a of the ply piece 9 forming the central region M is sandwiched between the two cut plies 14,. The length of the protruding portion 9a is preferably 10 mm or less, and if it is longer than 10 mm, the rigidity step of the belt layer 7 in the tire axial direction becomes large, and there is a risk that running stability may be reduced.

FIG. 5 shows another embodiment of the belt layer 7. In this example, the shoulder region is formed as a so-called hold ply that is folded in two at the belt end F using one cut ply 14A. Therefore, the inclination of the belt cord between the inner layer and the outer layer is reversed, and the belt layer 7
The stiffness is also improved. By forming as a fold ply in this manner, the inner layer and the outer layer are integrated at the belt end F, the peeling of the end of the belt layer 7 can be prevented, and the durability can be further improved.

[0025]

[Specific Example] A tire having a tire size of 190/50 R17 and having the structure shown in FIG. 1 was prototyped with the specifications shown in Table 1 (Examples 1 to 5) and its performance was tested. In addition, the tires having the conventional configuration (Comparative Example 1) and the tires (Comparative Examples 2 to 5) other than the configuration of the present application were also tested together and their performances were compared.

The test conditions are as follows. 1) Straight running stability, turning stability and riding comfort The vehicle was mounted on an actual vehicle, traveled on a straight road and a curved road with a radius of 400 m, respectively, determined by the feeling of a test driver, and indicated by an index with Comparative Example 1 being 100. .
The larger the value, the better. Tables 1 and 2 show the test results.

[0027]

[Table 1]

[0028]

[Table 2]

As a result of the test, it was confirmed that the example of the present invention was superior to the comparative example in the straight running stability and the turning stability was remarkably improved.

[0030]

As described above, in the pneumatic radial tire of the present invention, the central region of the belt layer is formed by ply pieces formed by spirally winding a belt-like ply, while the shoulder region is formed by cutting a cut ply into and out of two layers. Because it was formed
It can excel in straight running performance and greatly improve turning running performance.

[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 an example of a configuration of a belt layer of a carcass.

FIG. 3 is a cross-sectional view illustrating a belt-like ply.

FIG. 4 is a sectional view showing the winding.

FIG. 5 is a sectional view schematically showing another embodiment of the belt layer.

[Explanation of symbols]

 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 7 Belt layer 9 Ply piece 10 Belt ply 11, 15 Belt cord 12 Topping rubber 14, 14A Cut ply BW Belt width C Tire equator M Central area P Section point S Shoulder Area TW Tread width

Claims (1)

(57) [Claims] 1. A tire having a main body extending from a tread part through a sidewall part to a bead part and a winding part connected to the main part and turned around a bead core of the bead part, and having a winding angle of 70 to 90 degrees with respect to the tire equator. A carcass using one or more carcass plies having carcass cords inclined at an angle, and a carcass arranged inside the tread portion and radially outside the carcass and having a width in the tire axial direction of 0.88 of the tread width. A radial tire for motorcycles, comprising a belt layer having a belt layer having a width of not less than twice and not more than 0.92 times, wherein the belt layer has a tread width of not less than 0.2 times and not more than 0.35 times on both sides around a tire equator. A central region located inside a division point separated by a distance and two shoulder regions located outside the division point in the tire axial direction, and the elastic modulus of the central region is 600 kg /. The belt cord made of organic fibers of mm ² or more is covered with a topping rubber, and is formed of one or more ply pieces spirally wound at a small angle with respect to the tire equator by forming a long belt-like ply. The shoulder region is formed by superposing two layers of sheet-like cut plies in which a belt cord made of organic fibers is inclined at an angle of 10 ° or more and 40 ° or less with respect to the tire equator in and out of the radial direction. Radial tires for motorcycles.