JP2007290413A - Radial tire for motorcycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radial tire for a motorcycle capable of carrying stability at the time of turning, in addition to high speed durability, straight line stability and turning performance required as a tire for race, in particular. <P>SOLUTION: A spiral belt 2 is directly disposed at the outside of a radial carcass 1. A cord of the spiral belt 2 is made as a steel cord in a width direction center region 11, and is made as a highly-elastic organic fiber cord in width direction both outside regions 12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a spiral belt formed by winding a cord directly in the circumferential direction on the radially outer side of a radial carcass made of at least one carcass ply inclined by 60 to 90 degrees with respect to the circumferential direction. In particular, the present invention relates to a radial tire for a motorcycle in which a tread rubber located outside thereof is disposed, and particularly to a tire capable of ensuring high-speed durability, straight-running stability, turning performance, and stabilizing the behavior during turning.

  2. Description of the Related Art Conventionally, a radial tire for a motorcycle in which a spiral belt formed by winding a cord directly in the circumferential direction is arranged outside the radial carcass in the radial direction (see, for example, Patent Document 1).

  As a material for the cord forming the spiral belt, a material having high tension is used in order to suppress the circumferential extension of the tread portion generated by the centrifugal force during high-speed traveling. Specifically, a steel cord or a highly elastic material is used. It is exemplified that a spiral belt is formed by winding any one of the organic fiber cords over the entire width of the spiral belt.

  When a steel cord is used as the cord for the spiral belt, the effect of suppressing the radial expansion of the tread portion is high, which can contribute to high speed durability and straight running stability. In addition, when the vehicle turns and the tire receives a lateral force, the spiral belt is compressed in the circumferential direction. However, when the spiral belt is formed of a steel cord, the steel cord is sufficient for the compression force. Since it has rigidity, it can endure a large lateral force and can have a high turning performance. However, because the rigidity is too high, when the vehicle turns, it becomes sensitive to changes in lateral force in inverse proportion to the poor followability to the road surface and the fact that a large cornering force is obtained. However, there is a problem that the stability at the time of turning decreases.

On the other hand, when high elastic organic fiber is used as the cord for the spiral belt, there is no problem as long as it is used only for ordinary motorcycle tires, but when higher speed performance is required, such as motorcycle tires for racing. However, there is a problem that the tire is unsatisfactory in terms of high-speed durability, straight running stability, and the effect of suppressing the tire diameter growth during high-speed running.
Japanese Patent Laid-Open No. 5-4503

  The present invention has been made in view of the above-described problems, and in addition to high-speed durability, straight-running stability, and turning performance, which are particularly necessary for racing tires, carry the stability during turning. An object is to provide a radial tire for a motorcycle.

<1> is a spiral belt in which a cord is directly wound in the circumferential direction on the radially outer side of a radial carcass made of at least one carcass ply inclined by 60 to 90 degrees with respect to the circumferential direction. And in a radial tire for a motorcycle in which a tread rubber located outside thereof is arranged,
The spiral belt cord is a radial tire for a motorcycle in which a steel cord is used in a central region in the width direction and a highly elastic organic fiber cord is used in both outer regions in the width direction.

  <2> is the radial tire for a motorcycle according to claim 1, wherein the highly elastic organic fiber is an aromatic aramid organic fiber in <1>.

  The motorcycle <3> according to claim 1 or 2, wherein the spiral belt according to <1> or <2> is wound with one cord or a ribbon in which two cords are bundled. It is a radial tire.

  <4> is any one of <1> to <3>, wherein the ground contact width of the tire is mounted on the applicable rim, filled with the specified air pressure, and statically placed on the flat plate in a vertical position, and the maximum load capacity The width of the central region is 70 to 130% of the ground contact width when the maximum width of the contact surface to the flat plate of the tire when a load corresponding to is applied is applied. The described radial tire for motorcycles.

  <5> is any one of <1> to <4>, wherein the type of the tread rubber is different between the central region and both outer regions, and the modulus at 100% elongation at 80 ° C. The radial tire for a motorcycle according to any one of claims 1 to 4, wherein the tire is high in tread rubber in a central region and low in tread rubber in both outer regions.

  <6> In <5>, the modulus of the tread rubber in the central region at 100% elongation at 80 ° C. exceeds 0.6 MPa, and the tread rubber in both outer regions at 100% elongation at 80 ° C. The radial tire for a motorcycle according to claim 5, wherein the modulus of the motorcycle is 0.6 MPa or less.

  According to <1>, since the cord of the spiral belt is a steel cord in the center region in the width direction and a highly elastic organic fiber cord in both outer regions in the width direction, it uses the extremely high rigidity of the steel cord to run at high speed. High-speed organic fiber cords placed in both outer regions that contact the road surface when turning by tilting the vehicle while ensuring high-speed durability and straight-line stability by suppressing the diameter growth at the time Thus, it is possible to hold the turning stability while suppressing the turning force from changing sensitively depending on the inclination angle of the vehicle.

  According to <2>, since the high elastic organic fiber cord is made of an aromatic aramid fiber, moderate rigidity can be maintained, and a change in the turning force during turning can be more effectively suppressed. be able to.

  According to <3>, since the spiral belt is wound with one cord or a ribbon in which two cords are bundled, the spiral belt can be efficiently produced.

  According to <4>, since the width of the central region is 70 to 130% of the ground contact width, high-speed durability and straight-running stability during straight travel can be further ensured, and during cornering The turning force can be ensured more reliably.

  <5> According to <5>, the type of the tread rubber is made different between the central region and both outer regions, and the modulus of the tread rubber in the central region that affects the performance during straight running is increased, so that high speed durability is achieved. Performance and straight running stability can be further improved, and the modulus of the tread rubber in both outer areas, which affects the performance during turning, has been lowered, improving the followability to the road surface and improving turning stability. It can contribute and give the driver a sense of security.

  According to <6>, the modulus at 100% elongation of the tread rubber in the central region at 80 ° C. exceeds 0.6 MPa, and the modulus at 100% elongation of the tread rubber in both outer regions at 80 ° C. , 0.6 MPa or less, the effect of the above <5> can be highlighted. When the modulus of the tread rubber in the central region is 0.6 MPa or less, high-speed durability and straight running stability cannot be sufficiently improved, and the modulus of the tread rubber in both outer regions is If it exceeds 0.6 MPa, the turning stability cannot be sufficiently improved.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a motorcycle radial tire according to an embodiment in a cross section passing through a central axis, and FIG. 2 is a plan view of a radial carcass and a spiral belt as viewed from the outside in the tire radial direction. 1 is a developed view showing a radial tire 10 for a motorcycle with two layers in which both sides are folded around bead cores 9 on both sides and a central part is extended between these bead cores 9 in a toroidal shape. A radial carcass 1 composed of carcass plies 1a, 1b, a spiral belt 2 disposed adjacent to the radial carcass 1 in the radial direction and wound with a cord in the circumferential direction, and an outermost tread rubber 8. With

  Here, the spiral belt 2 includes a steel cord portion 2a formed by winding a steel cord in the tire circumferential direction, and a high rigidity organic fiber cord portion 2b formed by winding a high rigidity organic fiber cord in the tire circumferential direction. The steel cord portion 2a extends to a central region 11 located in the center in the tire width direction including the tire equatorial plane, and the high-rigidity organic fiber cord portion 2b is located on both outer sides in the width direction of the tire central region 11 respectively. Extends to the outer region 12.

  With such a configuration of the spiral belt 2, high-speed durability and straight-line stability can be ensured by the extremely high rigidity of the steel cord portion 2a disposed in the central region that is in contact with the road surface when straight-running. The turning stability can be supported by the mild rigidity of the high-elasticity organic fiber cord portions 2b disposed in the both side regions that are in contact with the road surface during turning.

  Here, the central region is preferably a region having a width of 70 to 130% of the tire ground contact width across the equator plane, whereby each of the steel cord portion 2a and the highly elastic organic fiber cord portion 2b is formed. An effect can be exhibited advantageously.

  Here, the “contact width” means that a tire is mounted on an applicable rim, and the tire is placed in a vertical posture on a flat plate under a specified air pressure, and a load corresponding to the maximum load capacity is applied. The maximum width of the contact surface of the tire with respect to the flat plate at the time.

  In this case, the “applicable rim” means a rim defined in the following standards according to the tire size, and the “specified air pressure” is defined in accordance with the maximum load capacity in the following standards. Air pressure. In this case, the “maximum load capacity” refers to the maximum mass allowed to be loaded on the tire according to the following standards.

  The standard is defined by an industrial standard effective in the region where tires are produced or used. For example, in the United States, “Year Book” of “The Tire and Rim Association Inc.”, in Europe, , “The European Tire and Rim Technical Organization”, “Standards Manual”, and in Japan, “JATMA Year Book” of the Japan Automobile Tire Association.

  Moreover, it is preferable to use an aromatic aramid fiber as the highly elastic organic fiber cord. Further, in order to wind in the circumferential direction of these cords including steel cords, one cord or two cords are used. It is preferable to use a ribbon with a bundle of

  It is preferable that the type of the tread rubber 8 is different between the central region 11 and the both outer regions 12, and the modulus of the tread rubber 8 a in the central region 11 at 100% elongation at 80 ° C. is higher than both the outer regions 12. As a result, the high-speed durability and the straight running stability can be further improved, and the stability during cornering can be further improved.

The absolute value of the modulus of each tread rubber 8a, 8b when 100% stretched at 80 ° C. is assumed that the modulus of the tread rubber 8a disposed in the central region 11 exceeds 0.6 MPa, and is disposed in both outer regions 12. The modulus of the tread rubber 8b is preferably 0.6 MPa or less.

  As an example, two types of tires having the structure shown in FIG. 1 were produced as prototypes, and these were designated as Example 1 and Example 2, respectively, for straight running stability at high speed running, turning stability at high speed running, And high-speed durability was evaluated. In addition, for the purpose of comparing tires with these, a comparative example in which only the spiral belt 2 in Example 1 is replaced with one formed by winding one kind of steel cord in the circumferential direction over the entire width is used as a comparative example. The same evaluation was performed. Table 1 shows the evaluation results and the main specifications of the tire constituent members.

  In addition, the straight running stability and the turning stability were evaluated based on the driver's score when traveling on the circumference circuit, and the evaluation result was expressed as an index with the conventional example as 100. The larger the number, the better the score. The high-speed durability is evaluated by a drum test with a rotating drum as a road surface. The load condition is 1750N, and the speed is 180km / h, and 10km / h is one step, and the speed is increased by one step every 10 minutes. Elevated and evaluated by which step the tire bursts. The result was expressed as an index with the conventional example as 100. The larger this value, the better the durability.

  The size of the tire used for this evaluation was 190 / 50ZR17, and this size tire was mounted on the rear of the vehicle when traveling on an actual vehicle. The rim to which the tire was attached was MT6.00x17inch, and the filled internal pressure was 190 kPa. Further, as the radial carcass of the tire, a tire in which two layers of carcass plies made of nylon cord were laminated was used. Further, in these tires, the width of the central region is the same as the contact width.

  As is clear from Table 1, the tires of the examples are superior to the conventional tires in terms of high-speed turning stability, and in particular, the tires of Example 2 and the preferred arrangement of the tread rubber have high-speed straight running stability and It also shows that the high-speed durability is superior to the conventional tire. In Table 1, “aramid” indicates “aromatic aramid fiber”.

  The present invention can be suitably used particularly for racing motorcycle tires.

1 is a cross-sectional view showing a motorcycle tire according to an embodiment of the present invention. 1 is a development plan view showing a belt structure of a motorcycle tire according to an embodiment of the present invention as viewed from the outside in the tire radial direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radial carcass 1a, 1b Carcass ply 2 Spiral belt 2ab Steel cord part 2 High-rigidity organic fiber cord part 8 Tread rubber 8a Tread rubber in the center region 8b Tread rubber in both outer regions 9 Bead core 10 Radial tire for motorcycle 11 Central region 12 Both outer areas

Claims (6)

A spiral belt formed by winding a cord directly in the circumferential direction on the radial direction outside of the radial carcass made of at least one carcass ply inclined at 60 to 90 degrees with respect to the circumferential direction, and on the outside In radial tires for motorcycles with a tread rubber located,
A radial tire for a motorcycle in which the cord of the spiral belt is a steel cord in a central region in the width direction and a highly elastic organic fiber cord in both outer regions in the width direction.   The radial tire for a motorcycle according to claim 1, wherein the highly elastic organic fiber is an aromatic aramid organic fiber.   The radial tire for a motorcycle according to claim 1 or 2, wherein the spiral belt is formed by winding one cord or a ribbon in which two cords are bundled.   Tire contact with the flat plate when the tire is mounted on the applicable rim, filled with the specified air pressure, placed in a vertical position on the flat plate, and a load corresponding to the maximum load capacity is applied. The radial tire for a motorcycle according to any one of claims 1 to 3, wherein a width of the central region is 70 to 130% of a contact width when the maximum width of the surface is set.   The type of the tread rubber is made different between the central region and both outer regions, and the modulus at 100% elongation at 80 ° C. is higher in the tread rubber in the central region, and lower in the tread rubber in both outer regions. The radial tire for a motorcycle according to any one of claims 1 to 4.   The modulus at 100% elongation at 80 ° C of the tread rubber in the central region exceeds 0.6 MPa, and the modulus at 100% elongation at 80 ° C of the tread rubber in both outer regions is 0.6 MPa or less. Item 6. A radial tire for a motorcycle according to Item 5.

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