JP2010163106A - Pneumatic tire for motorcycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire for a motorcycle, concurrently achieving turning performance and vibration absorbance. <P>SOLUTION: The dynamic modulus of elasticity of side rubber 32 at 30°C is set at 12 MPa or more. The dynamic modulus of elasticity of the side rubber under a lower strain state is set higher than a conventional one, so that lateral rigidity during ordinary running becomes higher than a conventional one, and when a camber angle is provided, no time delay occurs at a self steer, thus improving turning performance. A 300% elongation modulus at 30°C is set at 9 MPa or less, and therefore, in the state where deformation (distortion) of a sidewall portion becomes larger owing to getting over a protrusion or running on a road surface having excessively uneven portions, the modulus of the side rubber 32 does not become so high. Thus, the absorbance of vibration is kept equivalent to that of a conventional tire. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire for a motorcycle, and more particularly to a pneumatic tire for a motorcycle that can achieve both turning performance and vibration absorption.

  When a motorcycle is tilted, a motorcycle has a self-steer with a natural steering angle on the front tire. Due to the occurrence of self-steering, the front wheels generate a higher cornering force and thus can exhibit high turning performance.

2. Description of the Related Art In recent years, in motorcycles that place importance on sports driving, the vehicle body is tilted at a faster speed, so that a tire that does not cause a time delay in self-steering can provide higher turning performance.
As conventional tires for motorcycles, for example, those disclosed in Patent Documents 1 and 2 are known.

JP-A-8-216629 JP 2006-142922 A

  In the prior art, in order to reduce the time delay of the self-steering, it has been effective to increase the lateral rigidity and torsional rigidity of the tire. For this reason, the structure has been made heavy, such as an increase in the number of plies and an increase in the size of the bead filler. As a result, the tire weight is increased, other performances are deteriorated, and the cost is increased.

In addition, as a conventional improvement, there has been a method in which rubber having both a high dynamic elastic modulus (E ′) and a 300% elongation modulus (M300) is disposed on the sidewall portion. There was a tendency to get worse.
Further, there is a tire in which the tread portion and the sidewall portion are formed of one kind of rubber, but in this case, it is difficult to ensure the ozone crack resistance of the sidewall portion.

  In view of the above facts, an object of the present invention is to provide a pneumatic tire for a motorcycle that can achieve both turning performance and vibration absorption.

  The pneumatic tire for a motorcycle according to claim 1 is disposed on a carcass extending from one bead portion to the other bead portion, a belt disposed on a radially outer side of the carcass, and an outer side in the tire width direction of the carcass. A side rubber that forms the sidewall portion, and a tread rubber that is disposed outside the belt in the tire radial direction and forms a tread portion, and the dynamic elastic modulus of the side rubber at 30 ° C. is 12 MPa or more, and The 300% elongation modulus at 30 ° C. is 9 MPa or less.

Next, the operation of the pneumatic tire for a motorcycle according to claim 1 will be described.
In the pneumatic tire for a motorcycle according to claim 1, the dynamic elastic modulus of the side rubber at 30 ° C is 12 MPa or more, and the 300% elongation modulus at 30 ° C is 9 MPa or less.

  Since the pneumatic tire for a motorcycle according to claim 1 has a higher dynamic elastic modulus of the side rubber at the time of low strain than before, the lateral rigidity during normal running is increased, and when the camber angle is given, Turning performance can be improved without causing a time delay in self-steering.

  Also, in situations where the deformation (strain) of the sidewall portion increases due to overcoming the protrusion or running on a road with large irregularities, the dynamic elastic modulus of the side rubber at low strain is high. Since the modulus of the side rubber is not so high, the vibration absorption can be kept equal to that of the conventional tire.

  In the pneumatic tire for a motorcycle according to claim 1, the dynamic elastic modulus and modulus of the side rubber are optimized in order to reduce the time delay of the self-steer, and the increase in the number of plies, the bead filler There is no need for a heavy structure such as an increase in size, and there is no deterioration in other performance and an increase in cost due to an increase in tire weight.

In addition, when the dynamic elastic modulus at 30 ° C. of the side rubber is less than 12 MPa, the turning performance cannot be sufficiently improved.
On the other hand, when the 300% elongation modulus of the side rubber at 30 ° C. exceeds 9 MPa, vibration absorbability deteriorates.

In addition, the dynamic elastic modulus in this invention is measured on the measurement conditions of dynamic strain 1%, frequency 52Hz, and measurement temperature 30 degreeC using the spectrometer based on JISK7198.
Further, the 300% elongation modulus in the present invention is measured based on JIS K6301.

  The invention according to claim 2 is the pneumatic tire for a motorcycle according to claim 1, wherein the side rubber has a dynamic elastic modulus at 30 ° C of 35 MPa or less and a 300% elongation modulus at 30 ° C of 4 MPa or more. It is.

Next, the operation of the pneumatic tire for a motorcycle according to claim 2 will be described.
When the dynamic elastic modulus at 30 ° C. of the side rubber exceeds 35 MPa, the longitudinal spring constant of the tire becomes too high and the vibration absorbability deteriorates.
On the other hand, if the 300% elongation modulus at 30 ° C. of the side rubber is less than 4 MPa, it is difficult to improve the turning performance because the side rubber is too soft.

  As described above, since the pneumatic tire for a motorcycle according to the present invention has the above-described configuration, it has an excellent effect that both turning performance and vibration absorption can be achieved.

1 is a cross-sectional view of a pneumatic tire for a motorcycle according to a first embodiment of the present invention.

An embodiment of a pneumatic tire for a motorcycle according to the present invention will be described with reference to the drawings.
As shown in FIG. 1, the pneumatic tire 10 for a motorcycle according to this embodiment has a tire size of 120 / 70ZR17M / C and is attached to a wheel 11 of MT3.50-17.

  The pneumatic tire 10 for a motorcycle according to this embodiment includes a carcass 16 including a single carcass ply 12 in which a cord extending in a direction intersecting the tire equator plane CL is embedded. The carcass 16 may be composed of two or more carcass plies 12.

  The carcass ply 12 is wound up around the bead core 20 having both end portions embedded in the bead portion 18 from the tire inner side toward the outer side. In addition, the part which continues from one bead core 20 to the other bead core 20 is referred to as a main body part 12A, and the part where the bead core 20 is folded back outward in the tire radial direction is referred to as a folded part 12B. Note that a bead filler 28 extending from the bead core 20 while gradually decreasing the width from the bead core 20 to the outer side in the tire radial direction is disposed between the main body portion 12A and the folded portion 12B.

  A belt 22 is provided outside the carcass 16 in the tire radial direction. The belt 22 of the present embodiment is a so-called crossing belt, which is composed of a plurality of belt plies (two in this embodiment) including a plurality of cords that are inclined with respect to the tire circumferential direction. The cord is inclined in the opposite direction with respect to the tire equatorial plane CL, for example, at an angle of 20 to 40 °.

On the outer side of the belt 22 in the tire radial direction, a tread rubber 24A that constitutes a tread portion 24 that contacts the road surface is disposed.
In the tread portion 24, a main groove 26 for drainage is formed.

A side rubber 32 constituting a sidewall portion 30 that does not contact the road surface is disposed on the outer side in the tire width direction of the carcass 16.
In this embodiment, the side rubber 32 has a dynamic elastic modulus at 30 ° C. of 12 MPa or more and a 300% elongation modulus at 30 ° C. of 9 MPa or less. The side rubber 32 preferably has a dynamic elastic modulus at 30 ° C. of 35 MPa or less and a 300% elongation modulus at 30 ° C. of 4 MPa or more.

  In the pneumatic tire 10 for a motorcycle according to this embodiment, the side rubber 32 has a larger dynamic elastic modulus at 60 ° C. than the tread rubber 24A.

(Function)
The pneumatic tire 10 for a motorcycle according to this embodiment is attached to a front wheel of a motorcycle.
In the pneumatic tire 10 for a motorcycle according to the present embodiment, the rubber used for the tread portion 24 and the rubber used for the sidewall portion 30 are dedicated rubbers. Therefore, the side rubber 32 constituting the sidewall portion 30 has a tread rubber 24A. Also, rubber having excellent ozone crack resistance can be used, and ozone crack resistance can be ensured. Further, rubber having better grip and wear resistance than the side rubber 32 can be used for the tread rubber 24A, and the grip and wear resistance necessary for a motorcycle can be ensured.

  In the pneumatic tire 10 for a motorcycle according to the present embodiment, the dynamic elastic modulus of the side rubber 32 at 30 ° C. is set to 12 MPa or more, and the dynamic elastic modulus of the side rubber at the time of low strain is set higher than the conventional one. Lateral rigidity during running is higher than before, and when the camber angle is set, no time delay occurs in self-steering, and the turning performance is improved.

  Further, the pneumatic tire 10 for a motorcycle according to the present embodiment has a 300% elongation modulus at 30 ° C. of 9 MPa or less. Since the modulus of the side rubber 32 does not become so high in a situation where the (strain) increases, the vibration absorption can be kept equal to that of the conventional tire.

  Further, in the pneumatic tire 10 for a motorcycle according to the present embodiment, the dynamic elastic modulus and modulus of the side rubber 32 are optimized in order to reduce the time delay of self-steer, and the increase in the number of plies, the bead filler There is no need for a heavy structure, such as an increase in size, and there is no deterioration in other performance and an increase in cost due to an increase in tire weight.

(Test Example 1)
In order to confirm the effect of the present invention, one type of conventional tire and two types of tires of the example to which the present invention was applied were prototyped and mounted on an actual vehicle (displacement of 600 cc) to turn and absorb vibration. A comparison was made.
The test result is a feeling evaluation by the test rider when the test tire is mounted on the front wheel of the actual vehicle. The evaluation was a 10-point scale.
Both the conventional example and the example have the tire structure shown in FIG. 1, but the types of side rubbers are different as shown in Table 1.

試験の結果から、本発明の適用された実施例１，２のタイヤは、従来例のタイヤに比較して、振動の吸収性、及び旋回性共に向上していることが分かる。

From the test results, it can be seen that the tires of Examples 1 and 2 to which the present invention is applied are improved in both vibration absorption and turning performance as compared with the conventional tire.

10 Pneumatic tires for motorcycles 16 Carcass 22 Belt 24 Tread part 24A Tread rubber 30 Side wall part

Claims (2)

A carcass straddling one bead portion to the other bead portion;
A belt disposed radially outside the carcass;
Side rubber that is disposed outside the carcass in the tire width direction and forms a sidewall portion;
A tread rubber disposed on the outer side in the tire radial direction of the belt and forming a tread portion;
Have
A pneumatic tire for a motorcycle, wherein the side rubber has a dynamic elastic modulus at 30 ° C of 12 MPa or more and a 300% elongation modulus at 30 ° C of 9 MPa or less.   The pneumatic tire for a motorcycle according to claim 1, wherein the side rubber has a dynamic elastic modulus at 30 ° C of 35 MPa or less and a 300% elongation modulus at 30 ° C of 4 MPa or more.

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