JP2006273248A - Pneumatic tire for motorcycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire particularly obtaining high grip, high durability and high stability at cornering required for a sport type motorcycle of high power. <P>SOLUTION: Both sides in a tire width direction of a tread part 20 are formed by a second rubber member 22B having the smallest modulus and a central side in the tire width direction is formed by a first rubber member 22A of the second highest modulus. Therefore, enhancement of durability at a central part side and enhancement of stability at cornering are made compatible. Further, a third rubber member 22C of the highest modulus is arranged at the inner side in the tire width direction than the second rubber member 22B and thickness of the third rubber member 22C is smoothly and gradually reduced toward both sides in the tire width direction. Therefore, rapid fluctuation of handling by a bank angle is eliminated as compared with a conventional one in which the tread part 20 is formed by two kinds of rubber members and durability of the central part can be further enhanced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pneumatic tire for a motorcycle, and more particularly to a pneumatic tire for a motorcycle suitable for a sports motorcycle having improved grip, durability, and stability during cornering.

  2. Description of the Related Art In recent years, performance improvement has been remarkable in sports motorcycles, and the demand for tires has been increased accordingly. In particular, there have been increasing demands for grip, durability, and stability during cornering.

  Conventionally, as a pneumatic tire for a motorcycle, a rubber member constituting a tread portion is divided into a center portion side and a side portion side, and each rubber member is made different, thereby improving high-speed durability on the center portion side. In addition, there is a technique (for example, Patent Document 1) aimed at improving the grip force and the stability during cornering. However, this method is insufficient in terms of cornering stability in sports motorcycles that require particularly high cornering performance due to a change in gripping force with the vicinity of the divided portion as a boundary. Further, even on the wear surface, there is a tendency that uneven wear or the like is likely to occur near the divided portions.

  In addition, as a problem with the split type tread, when two types of compounds having greatly different moduli are used, the change in the longitudinal spring constant (rigidity) of the tire due to the difference in the bank angle becomes large, which is particularly high. In sports motorcycles that require cornering performance, the sense of stability during cornering will be insufficient.

  Furthermore, by using a compound having a low modulus on the side portion side, there is a problem that the occurrence of uneven wear is increased due to a significant decrease in rigidity on the outer side of the dividing position.

There are also tires with a tread with a so-called cap / base structure that uses two types of compounds (for example, Patent Document 2), but in the case of traveling at a maximum speed of 300 km / h or more, for example, with a high-powered motorcycle. The center portion durability performance (for example, against tread blow) could not be secured, and it was difficult to achieve both cornering stability and durability by this method.
JP-A-61-27707 JP 2002-347410 A

  The conventional product in which the rubber member constituting the tread part is divided into the center part side and the side part side is mainly for the purpose of center wear countermeasures for tourer motorcycles. For sports motorcycles, the compound is improved. It is difficult to ensure the performance only by As for the tread gauge, there is a problem in that handling of a size that is currently on the market will greatly damage the gauge.

  The present invention has been made to solve the above-mentioned problems, and in particular, when used in a high-power sports motorcycle, it is possible to obtain a high grip, high durability, and high stability during cornering. The purpose is to provide pneumatic tires.

  The conventional tread splitting technology for motorcycle tires has mainly been used as a center wear countermeasure for tourer-type motorcycles and has not been considered for stability. However, in recent years, sports motorcycles have a speed exceeding 300 km / h and are required to have athletic performance, and it is difficult to ensure performance only by improving the tread compound. A solution has become necessary. Regarding tread gauges, a large change in gauge for the size that has been put on the market in the past was unsuitable because it impaired handling. Therefore, it was necessary to aim at ensuring durability and cornering stability by changing the dividing method with the conventional gauge.

  The invention according to claim 1 is a pneumatic tire for a motorcycle in which the tread rubber layer forming the tread portion is formed of a plurality of types of rubber members. The tread portion is disposed on the center side in the tire width direction and forms a tread surface, and the second rubber is disposed on both sides of the first rubber member in the tire width direction and forms a tread surface. And a third rubber member disposed at least on the inner side in the tire width direction than the second rubber member and not exposed to the tread surface, the third rubber member having a thickness toward the outer side in the tire width direction. When the modulus of the first rubber member is Md1, the modulus of the second rubber member is Md2, and the modulus of the third rubber member is Md3, Md2 <Md1 <Md3 is satisfied. It is characterized by a door.

  Next, the operation of the pneumatic tire for a motorcycle according to claim 1 will be described.

  By forming the tread portion on both sides in the tire width direction with the second rubber member having the smallest modulus and forming the center side in the tire width direction with the first rubber member having the second highest modulus, durability on the center portion side Both improvement and stability improvement during cornering can be achieved.

  Further, a third rubber member having the highest modulus is disposed at least on the inner side in the tire width direction than the second rubber member, and the thickness of the third rubber member is gradually reduced gradually toward both sides in the tire width direction. Therefore, as compared with the conventional product in which the tread portion is formed of a rubber member that is different in the width direction, the handling fluctuation due to the bank angle can be eliminated, and the durability of the center portion can be further improved.

  According to a second aspect of the present invention, in the pneumatic tire for a motorcycle according to the first aspect, the Md1 is 3.5 MPa to 4.5 MPa, the Md2 is 2.5 MPa to less than 3.5 MPa, and the Md3 is 5 It is characterized by being 5 MPa or more and 9 MPa or less.

  Next, the operation of the pneumatic tire for a motorcycle according to claim 2 will be described.

  When Md1 is less than 3.5 MPa, it is too soft and the wear resistance and durability required at high speed are insufficient.

  On the other hand, when Md1 is 4.5 MPa or more, it is too hard, the absorbability of road surface irregularities is lowered, and the grip force is also lowered.

  Next, when Md2 is less than 2.5 MPa, it is good for improving the grip force, but the durability required at high speed becomes insufficient.

  On the other hand, when Md2 is 3.5 MPa or more, it is too hard and the gripping force is lowered, and the handling stability is lowered.

  Next, when Md3 is less than 5.5 MPa, the third rubber member corresponding to the base of the cap / base structure becomes too soft, and Md2 is set to 2 in order to ensure the rigidity of the second rubber member corresponding to the cap. The meaning set to .5 MPa or more and less than 3.5 MPa fades.

  On the other hand, when Md3 is 9 MPa or more, it is too hard and the absorbability of the road surface unevenness is lowered.

  The modulus in the present invention is a modulus (unit: 100%) when a tensile test is performed using a punched sample of dumbbell No. 3 at room temperature (25 ° C.) in accordance with JIS K6301. MPa).

  According to a third aspect of the present invention, in the pneumatic tire for a motorcycle according to the second aspect, (Md1−Md2) /Md1≦0.6 is satisfied.

  Next, the operation of the pneumatic tire for a motorcycle according to claim 3 will be described.

  When (Md1-Md2) / Md1> 0.6, the rigidity step in the tread width direction becomes too large, and the cornering stability in which the bank angle increases or decreases decreases.

  According to a fourth aspect of the present invention, in the pneumatic tire for a motorcycle according to any one of the first to third aspects, in the tread rubber layer, an average modulus value obtained by averaging in the thickness direction is: It is characterized by a gradual decrease from the tire equatorial plane side toward both sides in the tire width direction.

  Next, the operation of the pneumatic tire for a motorcycle according to claim 4 will be described.

  The change in the tread rigidity in the tread width direction becomes gradual, and the stability during cornering in which the bank angle increases or decreases can be improved.

  According to a fifth aspect of the present invention, in the pneumatic tire for a motorcycle according to any one of the first to fourth aspects, in the tread rubber layer, an average modulus value obtained by averaging in the thickness direction is: It is characterized by a change rate within 30% in the tire width direction.

  Next, the operation of the pneumatic tire for a motorcycle according to claim 5 will be described.

  In the case of a pneumatic tire for a motorcycle, since the longitudinal spring constant tends to increase as the bank angle increases, the average modulus value obtained by averaging the thickness direction in the tread rubber layer is within 30% in the tire width direction. By keeping the change rate, the change in rigidity of the tread becomes gentle in the tread width direction, and the stability during cornering can be improved.

  According to a sixth aspect of the present invention, in the pneumatic tire for a motorcycle according to any one of the first to fifth aspects, the tread rubber layer has only the first rubber member at the center in the tire width direction. It is formed, and both sides thereof have a two-layer structure of the second rubber member and the third rubber member.

  A seventh aspect of the invention is the pneumatic tire for a motorcycle according to any one of the first to sixth aspects, wherein the third rubber member extends over the entire surface in the tire width direction. It is characterized by being arranged.

  The invention according to claim 8 is the pneumatic tire for a motorcycle according to any one of claims 1 to 7, wherein the boundary between the first rubber member and the second rubber member is a bank. It is characterized by being set so as to be located in the center of the contact surface width direction at an angle of 20 °.

  Next, the operation of the pneumatic tire for a motorcycle according to claim 8 will be described.

  By setting the boundary between the first rubber member and the second rubber member to be located in the center of the contact surface width direction when the bank angle is 20 °, changes in handling during cornering can be made smooth. .

  The bank angle is an angle of the tire equator plane with respect to a normal line standing perpendicular to the road surface.

  A ninth aspect of the present invention is the pneumatic tire for a motorcycle according to any one of the first to eighth aspects, wherein the negative rate of the tread portion is 12% or less.

  Next, the operation of the pneumatic tire for a motorcycle according to claim 9 will be described.

  When sports or circuit use is assumed, a negative rate of 12% or less is preferable in terms of improving ground contact.

  As described above, since the pneumatic tire for a motorcycle according to the present invention has the above-described configuration, it has high cornering, high durability, and high stability required for a high-power sports motorcycle. Has an excellent effect.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the pneumatic tire 10 for a motorcycle according to the present embodiment extends in a toroidal manner between a pair of bead cores 12 and folds each side portion around the bead core 12 to be wound outward in the radial direction. , A carcass 16 composed of at least one ply is provided.

  A belt 18 made of at least one ply is disposed outside the radial carcass 16 in the tire radial direction, and a tread portion 20 that extends in an arc shape up to the maximum width position of the tire is provided on the outer peripheral side of the belt 18. A tread rubber layer 22 is provided. Further, side rubber layers 26 that form side portions 24 are provided on both sides of the tread rubber layer 22 on the outer peripheral side of the belt 18.

  The internal structure of the pneumatic tire 10 for a motorcycle is the same as that of a sports type pneumatic tire for a motorcycle (radial structure) except for the tread rubber layer 22, and may have a structure other than that shown in FIG.

  As shown in FIG. 2, the tread rubber layer 22 of the present embodiment is arranged on the tire width direction center side and on the both sides in the tire width direction of the first rubber member 22A forming the tread surface and the first rubber member 22A. The second rubber member 22B is disposed and forms a tread surface, and the third rubber member 22C is disposed on the inner side in the tire width direction of the second rubber member 22B and is not exposed to the tread surface.

  In FIG. 2, reference numeral 20C indicates a tread surface, reference numeral 20A indicates a grounding end, reference numeral 20B indicates an outermost end of the tread rubber layer 22, and the road surface is not grounded between the grounding end 20A and the outermost end 20B. Part.

  In the present embodiment, the inner peripheral surface of the first rubber member 22A is in contact with the outermost surface of the belt 18, and the width gradually increases toward the outer side in the tire radial direction.

  In the present embodiment, the third rubber member 22C has an inner peripheral surface that is in contact with the outermost surface of the belt 18, a tire equatorial plane CL side that is in contact with a side surface of the first rubber member 22A, and the thickness thereof is the outermost end. It gradually decreases toward 20B. That is, the thickness of the third rubber member 22C gradually decreases from the tire equatorial plane CL side toward the outer side in the tire width direction between the ground contact ends.

  In the present embodiment, the second rubber member 22B has an inner peripheral surface in contact with the outer peripheral surface of the third rubber member 22C, and a tire equatorial plane CL side is in contact with a side surface of the first rubber member 22A.

  Note that the thickness of the tread rubber layer 22 is substantially constant between the both grounded ends, and decreases rapidly from the grounded end 20A toward the outermost end 20B.

  Here, when the modulus of the first rubber member 22A is Md1, the modulus of the second rubber member 22B is Md2, and the modulus of the third rubber member 22C is Md3, Md2 <Md1 <Md3 is satisfied. .

  Md1 is preferably 3.5 MPa or more and 4.5 MPa or less, Md2 is preferably 2.5 MPa or more and less than 3.5 MPa, and Md3 is preferably 5.5 MPa or more and 9 MPa or less.

  Furthermore, it is preferable to satisfy (Md1-Md2) /Md1≦0.6.

  When the modulus of the tread rubber layer 22 is averaged in the thickness direction, it is preferable that the average value of the modulus gradually decreases toward both sides in the tire width direction.

  Further, the average value of the modulus in the tread rubber layer 22 is preferably a change rate within 30% in the tire width direction.

  The boundary SL between the first rubber member 22A and the second rubber member 22B is set so as to be located in the center area in the contact surface width direction (the center area when the contact width is divided into three equal parts) when the bank angle is 20 °. It is preferable to do.

In the pneumatic tire 10 for a motorcycle according to the present embodiment, the groove for drainage is not formed in the tread portion 20, but a groove may be formed. However, it is preferable to set the negative rate of the tread portion 20 to 12% or less in order to place importance on the grounding property.
(Function)
Next, the effect | action of the pneumatic tire 10 for two-wheeled vehicles of this embodiment is demonstrated.

  In the pneumatic tire 10 for a motorcycle according to the present embodiment, both sides in the tire width direction of the tread portion 20 are formed by the second rubber member 22B having the smallest modulus, and the center side in the tire width direction is the first having the second highest modulus. Since it is formed of the rubber member 22A, both the improvement in durability on the center side and the improvement in stability during cornering are compatible. In addition, the third rubber member 22C having the highest modulus is arranged on the inner side in the tire width direction than the second rubber member 22B, and the thickness of the third rubber member 22C is gradually and gradually reduced toward both sides in the tire width direction. As a result, it is possible to eliminate the sudden fluctuation of the handling due to the bank angle and further improve the durability of the center portion as compared with the conventional product in which the tread portion 20 is formed of two types of rubber members.

  In addition, when Md1 of the first rubber member 22A is less than 3.5 MPa, the wear resistance and durability required at high speed are insufficient due to being too soft. On the other hand, if the Md1 of the first rubber member 22A is 4.5 MPa or more, it is too hard to reduce the unevenness of the road surface, and the grip force also decreases.

  Next, when the Md2 of the second rubber member 22B is less than 2.5 MPa, it is good for improving the grip force, but the durability required at high speed becomes insufficient. On the other hand, when the Md2 of the second rubber member 22B is 3.5 MPa or more, it is too hard and the gripping force is lowered, and the handling stability is lowered.

  Next, when the Md3 of the third rubber member 22C is less than 5.5 MPa, the third rubber member 22C becomes too soft, and Md2 is set to 2.5 MPa or more to ensure the rigidity of the second rubber member 22B. The meaning set to less than 5 MPa fades. On the other hand, if the Md3 of the third rubber member 22C is 9 MPa or more, it is too hard and the unevenness of the road surface unevenness decreases.

  Further, when (Md1-Md2) / Md1> 0.6, the rigidity step in the tread width direction becomes too large, and the stability during cornering in which the bank angle increases or decreases decreases.

  In the tread rubber layer 22, the average modulus value obtained by averaging in the thickness direction is gradually decreased from the tire equatorial plane side toward both sides in the tire width direction, so that the change in rigidity of the tread portion 20 becomes gradual. Stability can be improved.

  Moreover, in the tread rubber layer 22, the average modulus value averaged in the thickness direction is kept within a change rate of 30% or less in the tire width direction, so that the change in rigidity of the tread portion 20 is moderated in the tread width direction. Thus, stability during cornering can be improved.

  By setting the boundary SL between the first rubber member 22A and the second rubber member 22B to be located in the center of the contact surface width direction when the bank angle is 20 °, changes in handling during cornering are smoothed. I can do it.

Further, by setting the negative rate of the tread portion 20 to 12% or less, the ground contact property is improved, and a high grip force can be obtained in sports running and circuit running.
[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment, and the description is abbreviate | omitted.

  As shown in FIG. 3, in the pneumatic tire 10 for a motorcycle according to the present embodiment, the third rubber member 22C is continuously extended from one outermost end 20B of the tread rubber layer 22 to the other outermost end 20B. The thickness thereof is the thickest on the tire equatorial plane CL, and gradually decreases toward the outermost end 20B. The first rubber member 22A and the second rubber member 22B are both disposed on the outer peripheral side of the third rubber member 22C.

  In the pneumatic tire 10 for a motorcycle according to this embodiment, the arrangement of the third rubber member 22C is different from that of the first embodiment, but the same effects as those of the first embodiment can be obtained.

(Test example)
In order to confirm the effect of the present invention, two types of conventional tires and two types of tires according to the present invention were prepared, and the durability of the center portion and the steering stability during cornering were compared. .
Example 1 It has a tread structure shown in FIG. Other specifications are as described in Table 1.
Example 2: It has a tread structure shown in FIG. Other specifications are as described in Table 1.
Conventional Example 1: It has a tread structure shown in FIG. Other specifications are as described in Table 1.
Conventional Example 2: It has a tread structure shown in FIG. Other specifications are as described in Table 1.

  Steering stability evaluation is a feeling evaluation of a test rider when a test tire is mounted on a motorcycle and travels on a test course. In addition, evaluation is an index display in which Conventional Example 1 is set to 100, and the larger the value, the better the performance.

  Further, the durability of the center portion is an index display with the conventional example 1 as 100, and the larger the value, the better the performance.

  From the test results, it can be seen that the tires of the examples to which the present invention is applied all have higher steering stability during cornering while ensuring the durability of the center portion.

1 is a cross-sectional view of a pneumatic tire for a motorcycle according to a first embodiment. 1 is a cross-sectional view of a tread of a pneumatic tire for a motorcycle according to a first embodiment. 3 is a cross-sectional view of a tread of Example 2. FIG. It is sectional drawing of the tread of the prior art example 1. FIG. It is sectional drawing of the tread of the prior art example 2.

Explanation of symbols

10 pneumatic tire for motorcycle 12 bead core 16 radial carcass 18 belt 20 tread portion 20A grounding end 20B outermost end 22 tread rubber layer 22A first rubber member 22B second rubber member 22C third rubber member 24 side portion 26 side rubber Layer CL Tire equatorial plane SL boundary

Claims (9)

A tread rubber layer forming a tread portion is a pneumatic tire for a motorcycle constituted by a plurality of types of rubber members,
The tread portion is disposed on the center side in the tire width direction and forms a tread surface; and the second rubber member is disposed on both sides of the first rubber member in the tire width direction and forms a tread surface. A third rubber member disposed at least on the inner side in the tire width direction than the second rubber member and not exposed to the tread surface,
The thickness of the third rubber member gradually decreases toward the outer side in the tire width direction,
When the modulus of the first rubber member is Md1, the modulus of the second rubber member is Md2, and the modulus of the third rubber member is Md3, Md2 <Md1 <Md3 is satisfied. Pneumatic tires for motorcycles.   The air for a motorcycle according to claim 1, wherein the Md1 is 3.5 MPa or more and 4.5 MPa or less, the Md2 is 2.5 MPa or more and less than 3.5 MPa, and the Md3 is 5.5 MPa or more and 9 MPa or less. Enter tire.   The pneumatic tire for a motorcycle according to claim 2, wherein (Md1-Md2) /Md1≦0.6 is satisfied.   The average modulus value obtained by averaging in the thickness direction in the tread rubber layer gradually decreases from the tire equatorial plane side toward both sides in the tire width direction. A pneumatic tire for a motorcycle according to claim 1.   The average modulus value obtained by taking an average in the thickness direction in the tread rubber layer is within a change rate of 30% or less in the tire width direction. The pneumatic tire for a motorcycle according to the item.   The tread rubber layer is formed of only the first rubber member at the center in the tire width direction, and both sides thereof have a two-layer structure of the second rubber member and the third rubber member. The pneumatic tire for a motorcycle according to any one of claims 1 to 5.   The pneumatic tire for a motorcycle according to any one of claims 1 to 6, wherein the third rubber member is disposed over the entire surface in the tire width direction of the tread rubber layer. .   The boundary between the first rubber member and the second rubber member is set so as to be positioned at the center in the width direction of the ground plane when the bank angle is 20 °. The pneumatic tire for a motorcycle according to any one of the above.   The pneumatic tire for a motorcycle according to any one of claims 1 to 8, wherein a negative rate of the tread portion is 12% or less.

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