JP2009029211A - Pneumatic tire for motorcycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire for a motorcycle which is improved in driving performance and braking performance at the application of a moderate camber angle to a tire without causing axiety about traveling stability. <P>SOLUTION: A pneumatic tire for a two-wheeled motor vehicle has a tread 1, a side wall 2 and a bead 3. The tread 1 is formed of five regions of a center tread region A, shoulder tread regions C and intermediate tread section regions B. The intermediate tread regions B are grounded when 20-30° of a camber angle is applied. A 100% modulus of a part forming at least the grounding surface of intermediate tread rubber 7b placed in the entire intermediate tread region B is set greater than those of the 100% modulus of a part forming at least the grounding surface of center tread rubber 7a placed in the entire center tread region A and the 100% modulus of a part forming at least the grounding surface of shoulder tread rubber 7c placed in the entire shoulder tread region C. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire for a motorcycle.

When cornering with motorcycle tires, unlike so-called four-wheeled vehicle tires such as passenger cars, buses, trucks, etc. that mainly corner the tire by giving a slip angle, the camber tilts the tire with respect to the road surface. It is necessary to add corners.
For this reason, in a motorcycle tire, the contact area of the tread portion differs greatly between straight traveling and cornering.

That is, when traveling straight, the central tread region including the tire equatorial surface of the tread functions on the road surface and functions to transmit driving force and braking force to the road surface, and when cornering, the shoulder including the tread grounding end. The tread region is grounded on the road surface and functions to generate a lateral force that opposes the centrifugal force acting on the motorcycle.
The intermediate tread portion region located in the middle of these regions should transmit a driving force and a braking force to the road surface, for example, at a corner rise, and generate a lateral force against the centrifugal force at the cornering. Will also work.

  Therefore, the tread rubber disposed in the tread portion contact area of the motorcycle tire can be selected in each contact area only by selecting a single rubber type, a single rubber hardness, etc. The function of could not be fully demonstrated.

  Therefore, for example, in Patent Document 1, the contact area of the tread portion is divided into three areas of a center area and a shoulder area, and the tread rubber disposed in each of these areas is a loss tangent, dynamic By using a rubber material with an appropriate ratio to the modulus of elasticity, air for motorcycles is intended to improve high-speed durability during straight running by the center area and to improve grip and stability during cornering by the shoulder area. Entered tires are described.

However, although the pneumatic tire for a motorcycle described in Patent Document 1 can realize improvement in high-speed durability due to the center area and improvement in grip performance and stability during cornering due to the shoulder area, the tire In particular, the driving force and braking force required for the intermediate region straddling both the center region and the shoulder region that contact the road surface at the corner rise during cornering, etc., are countered against the centrifugal force. The generation of lateral force as force was still insufficient.
In addition, the pneumatic tire for a motorcycle tends to easily generate uneven wear or the like in the vicinity of the intermediate tread region due to cornering.

In addition, for example, when two types of tread rubbers with greatly different ratios of loss tangent to dynamic elastic modulus are used in the center area and the shoulder area, different types of rubber are grounded sequentially or simultaneously when the camber angle increases or decreases. As a result, the contact property of the tread rubber changes abruptly as the camber angle changes, which may result in insufficient running stability during cornering.
JP 2006-273240 A

  Accordingly, the present invention provides a pneumatic tire for a motorcycle, in particular, which has improved drivability and braking performance when imparting a middle camber angle to the tire without worrying about running stability.

  A pneumatic tire for a motorcycle according to the present invention includes a tread portion including a tread rubber having a layer structure of one or more layers, and a pair of sidewall portions extending inward in the tire radial direction continuously to each side portion of the tread portion. And a bead portion continuous on the inner side in the tire radial direction of the sidewall portion, wherein a contact area of the tread portion is a central tread portion region including a tire equatorial plane and a pair of shoulders including a tread ground contact end. It consists of five areas, a tread area, and a pair of intermediate tread areas located between the central tread area and the shoulder tread area, and the intermediate tread area is given a camber angle of 20-30 °. At least the ground contact surface of the intermediate tread rubber disposed throughout the intermediate tread portion region as a region to be grounded at times 100% modulus of the portion to be formed is 100% modulus of the portion that forms at least the ground contact surface of the central tread rubber disposed over the entire central tread portion region, and the shoulder is disposed over the entire shoulder tread region. The tread rubber is characterized in that it is larger than at least the 100% modulus of the portion forming the ground contact surface.

Here, “the tread rubber having at least one layer structure” means not only a case where the tread rubber of the tread portion has a single layer structure but also a tread rubber having a laminated structure such as a cap-and-base structure.
“Area to be grounded when a camber angle of 20 to 30 ° is applied” is defined as JATMA (THE Japan Automobile Tires Association, Inc.) YEAR BOOKE, ETRTO (European Tire and Rim T and RIM ASSOCIATION INC.) Mounted on the applicable rim specified by the YEAR BOOK, filled with the internal pressure specified by JATMA, etc., and loaded with a rear wheel load (when a rider rides a 150 kg rider) The area to be grounded when a camber angle of 30 ° is given.

  Here, 100% modulus is a tensile stress measured by preparing a JIS dumbbell-shaped No. 3 sample and conducting a tensile test at a speed of 500 ± 25 mm / min at room temperature in accordance with JIS K6251.

  More preferably, in such a tire, the 100% modulus of the central tread rubber is larger than the 100% modulus of the shoulder tread rubber.

  Also preferably, the 100% modulus of the intermediate tread rubber is in the range of 1.3 to 2.1 Mpa.

  More preferably, the 100% modulus of the central tread rubber is in the range of 1.0 to 1.8 Mpa, and the 100% modulus of the shoulder tread rubber is in the range of 0.9 to 1.7 Mpa.

  In any one of the tires described above, it is preferable to display on the sidewall portion that the tire is for mounting a rear wheel of a motorcycle.

In pneumatic tires for motorcycles, the central tread area that contacts the ground when traveling straight requires physical properties suitable for efficiently transmitting driving and braking forces to the road surface, and the shoulder tread area that contacts the ground during cornering is It is necessary to have physical properties suitable for generating sufficient lateral force.
In addition, in the intermediate tread area of the tread located between these two areas, in addition to efficient road surface transmission of driving force and braking force at the corner rise, etc., physical properties that can generate sufficient lateral force Must be granted.

  Therefore, in the pneumatic tire for a motorcycle according to the present invention, the contact area of the tread portion includes a central tread region including the tire equator plane, a pair of shoulder tread regions including a tread grounding end, a central tread region and a shoulder. It consists of five areas with a pair of intermediate tread areas located between the tread areas, and the intermediate tread areas are areas that are grounded when a camber angle of 20 to 30 ° is applied. The necessary physical properties are provided for each contact area, and each performance can be made compatible.

  That is, when the angle is less than 20 °, not only the driving force and braking force at the corner rising are transmitted, but also the rigidity for generating the lateral force cannot be ensured, the rigidity of the central tread portion region is increased and the absorbability is deteriorated. On the other hand, if it exceeds 30 °, not only can the driving force and braking force at the time of corner rise be transmitted, but also the rigidity to generate lateral force cannot be ensured, the rigidity of the shoulder tread region that contacts the ground during cornering increases, and the absorbency increases. Causes deterioration.

  In the pneumatic tire for motorcycles of the present invention, attention was paid to the modulus of the tread rubber as rigidity against the extension of the tread portion due to external force. As a measure of the modulus, 100% modulus, which is a value at 100% elongation at which data is relatively stable, was adopted.

  100% modulus of the intermediate tread rubber forming at least the ground contact surface, 100% modulus of the central tread rubber forming at least the ground contact surface, and shoulder tread rubber forming at least the ground contact surface In particular, by ensuring a high rigidity in the middle tread portion region that contacts the ground at the corner rise where a middle camber angle is imparted to the tire, Since the lateral rigidity can be increased, high drive performance and braking performance can be exhibited in the intermediate tread portion region, and a lateral force sufficient to resist centrifugal force can be exhibited.

Hereinafter, a pneumatic tire for a motorcycle according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a meridian cross-sectional view showing one embodiment of a pneumatic tire for a motorcycle of the present invention.

  In FIG. 1, 1 is a tread portion, 2 is a pair of sidewall portions extending radially inward continuously to the respective side portions of the tread portion 1, and 3 is radially inward of the sidewall portion 2. Each bead portion is shown.

  The tire has a carcass ply 5 that is folded from the tread portion 1 through the sidewall portion 2 and around the bead core 4 of the bead portion 3. In the drawing, the carcass is constituted by a single carcass ply 5, but a carcass can also be constituted by a plurality of carcass plies.

A belt 6 made of at least one circumferential reinforcing cord layer is disposed on the outer peripheral side of the crown region of the carcass ply 5. For example, one or a plurality of cords of the belt 6 are connected to the tire circumferential direction. It can be set as what is called a spiral belt structure wound continuously by the extended attitude to.
A tread rubber 7 that extends in an arc shape to the maximum width position of the tire and forms a contact area of the tread portion 1 is provided on the outer peripheral side of the belt 6. Further, side rubbers 8 that form side portions are provided on both sides of the tread rubber 7.
Furthermore, although omitted in FIG. 1, a required groove is formed on the surface of the tread rubber 7.

  In the tire shown here, the contact area of the tread portion 1 includes a central tread portion region A that includes the tire equatorial plane, a shoulder tread portion region C that includes the tread ground contact edge, and a central tread portion region A. The shoulder tread region C and the intermediate tread region B are formed in five regions with the intermediate tread region B positioned between the shoulder tread region C, and the shoulder tread region C and the intermediate tread region B are symmetric with respect to the equator plane. A pair is formed.

  And let the intermediate tread part area | region B be an area | region earth | grounded when the camber angle of 20-30 degrees is provided. Accordingly, the center tread portion region A is a region that contacts when a camber angle is applied at less than 20 °, and the shoulder tread portion region C is a region that contacts when a camber angle is applied beyond 30 °. .

In addition, here, the tread rubber 7 disposed in each of the regions has a single-layer structure, and at least the portion of the intermediate tread rubber 7b disposed over the entire intermediate tread portion region B that forms the ground contact surface. The shoulder tread rubber 7c in which the 100% modulus of the central tread rubber 7a disposed over the entire center tread region A is at least a portion that forms the ground contact surface and the shoulder tread region C Of at least the portion forming the ground plane is made larger than 100% modulus.
More preferably, the 100% modulus of the central tread rubber 7a is set larger than the 100% modulus of the shoulder tread rubber 7c.

  In motorcycle tires, the central tread region A of the tread portion 1 of the tire is mainly grounded during straight traveling, while the camber angle is applied during cornering so that the tire contact region becomes the central tread of the tread portion 1. The region A shifts to the shoulder tread region C. Comparing the traveling frequency of straight traveling and cornering traveling, the frequency of straight traveling is much higher. Therefore, rubber with emphasis on wear resistance is placed in the center tread area A, and grip force is applied in the shoulder tread area C. By disposing rubber with an emphasis on this, a tire excellent in both wear resistance and cornering properties can be obtained.

  This pneumatic tire for motorcycles secures high rigidity in the intermediate tread portion region B that contacts the ground at the corner rise where a medium camber angle is imparted to the tire, thereby improving the longitudinal rigidity and lateral rigidity of the tire. Since it can be increased, the intermediate tread portion region B can exhibit high driving performance and braking performance, and can exhibit a lateral force sufficient to resist centrifugal force.

  And the rigidity which can respond to each of high driving force, braking force, and lateral force is securable by making 100% modulus of intermediate tread rubber 7b into the range of 1.3-2.1Mpa.

  If the 100% modulus of the intermediate tread rubber 7b is less than 1.3 Mpa, there is a tendency that sufficient driving force and lateral force cannot be secured due to insufficient rigidity. If it exceeds 2.1 Mpa, the rigidity is too high and vibration due to unevenness of the road surface. There is a tendency that the absorbability and the grounding property of the steel deteriorate.

  By setting the 100% modulus of the central tread rubber 7a in the range of 1.0 to 1.8 Mpa and the 100% modulus of the shoulder tread rubber 7c in the range of 0.9 to 1.7 Mpa, each wear resistance And excellent cornering performance can be ensured.

  If the 100% modulus of the central tread rubber 7a is less than 1.0 Mpa, the wear resistance tends to decrease due to insufficient rigidity, and if it exceeds 1.8 Mpa, the rigidity is too high and the absorbability to unevenness of the road surface decreases. Tend.

  If the 100% modulus of the shoulder tread rubber 7c is less than 0.9 Mpa, the rigidity is too low to be able to secure rigidity capable of withstanding lateral force. There is a tendency for the absorbability to decrease.

  In the case of a motorcycle, since the rear wheel (rear) is a driving wheel, the present invention is greatly effective when applied to a tire for mounting a rear wheel, and the sidewall portion 2 is a tire for mounting a rear wheel of a motorcycle. indicate.

Next, a radial tire having a structure as shown in FIG. 2 and having a rear tire size of 190 / 50ZR17, provided with a monofilament spiral belt and a nylon carcass is manufactured as shown in Tables 1 and 2. The drivability was evaluated for each of Example Tire 1 to Example Tire 4 and Comparative Example Tire 1 to Comparative Example Tire 4 in which the specifications were changed.
The size of the front tire was a radial tire of 120 / 70ZR17, and the evaluation vehicle had a displacement of 1000 cc.
In the present invention, since the tire structure other than the tread portion does not require modification, the tire structure is substantially the same as that of a conventional pneumatic tire for motorcycles.

(Drivability)
Each of Example tire 1 to Example tire 4 and Comparative example tire 1 to Comparative example tire 4 is mounted on a rim having a rim size MT6.00, the internal pressure is 290 kPa, the load is 150 kg, the test speed is 30 to 300 km / h, and the vehicle is running. Table 3 shows a driving course evaluated by a rider's feeling by repeatedly running a round course of 4 km at a camber angle of 0 to 45 °.
The index of the comparative tire 1 was evaluated as a control. It shows that it is so favorable that an index value is large.

  From the results of Table 3, Example Tire 1 to Example Tire 4 were able to demonstrate sufficient driving force with respect to Comparative Example Tire 1 to Comparative Example Tire 4.

  Each of Example Tire 1 to Example Tire 4 and Comparative Example Tire 1 to Comparative Example Tire 4 was evaluated for vibration absorbability due to unevenness on the road surface, and will be described below.

(Absorbency)
A round course with a load of 150 kg, a test speed of 30 to 300 km / h, and a travel distance of 4 km, with a camber angle of 0 to 45 °, the amplitude of vibration due to the unevenness of the road surface, and the camber angle at which the vibration starts is Table 4 shows the absorbency evaluated by the rider's feeling.
The value of Comparative Example Tire 1 was displayed as an index as a control. A larger numerical value indicates better absorbability.

  From the results of Table 4, Example tire 1 to Example tire 4 were able to secure sufficient absorbency with respect to Comparative example tire 1 to Comparative example tire 4.

  From the results of Tables 3 to 4, Example Tire 1 to Example Tire 4 were superior in driving performance and absorbability to Comparative Example Tire 1 to Comparative Example Tire 4.

1 is a cross-sectional view in the width direction showing one embodiment of a pneumatic tire for a motorcycle of the present invention. FIG. 3 is a cross-sectional view in the width direction showing another embodiment of the pneumatic tire for motorcycles of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Bead core 5 Carcass ply 6 Belt 7 Tread rubber 7a Central tread rubber 7b Intermediate tread rubber 7c Shoulder tread rubber 8 Side rubber A Central tread part area B Middle tread part area C Shoulder tread part area

Claims (5)

A tread portion including tread rubber having a layer structure of one or more layers, a pair of sidewall portions extending inward in the tire radial direction continuously to the respective side portions of the tread portion, and inward of the tire radial direction of these sidewall portions. In a pneumatic tire for a motorcycle having a continuous bead portion,
The contact area of the tread portion includes a central tread portion region including a tire equatorial plane, a pair of shoulder tread regions including a tread grounding end, and a pair of intermediate positions between the central tread portion region and the shoulder tread portion region. The tread portion region is composed of five regions, and the intermediate tread portion region is a region to be grounded when a camber angle of 20 to 30 ° is applied, and at least the intermediate tread rubber disposed over the entire intermediate tread portion region. The 100% modulus of the portion forming the ground plane is disposed over the entire shoulder tread region and the 100% modulus of the portion forming the ground plane of the central tread rubber disposed over the entire central tread region. 10 of the portion of the shoulder tread rubber provided that forms at least the ground contact surface The pneumatic tire for a motorcycle, wherein the% larger than either of the modulus.   The pneumatic tire for a motorcycle according to claim 1, wherein the central tread rubber has a 100% modulus larger than that of the shoulder tread rubber.   The pneumatic tire for a motorcycle according to claim 1 or 2, wherein a 100% modulus of the intermediate tread rubber is in a range of 1.3 to 2.1 Mpa.   The 100% modulus of the central tread rubber is in the range of 1.0 to 1.8 Mpa, and the 100% modulus of the shoulder tread rubber is in the range of 0.9 to 1.7 Mpa. The pneumatic tire for motorcycles described.   The pneumatic tire for a motorcycle according to any one of claims 1 to 6, wherein a tire for mounting a rear wheel of a motorcycle is displayed on a sidewall portion.

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