WO2007052701A1

WO2007052701A1 - Pneumatic tire for two-wheeled vehicle

Info

Publication number: WO2007052701A1
Application number: PCT/JP2006/321861
Authority: WO
Inventors: Hidemitsu Nakagawa
Original assignee: Bridgestone Corporation
Priority date: 2005-11-02
Filing date: 2006-11-01
Publication date: 2007-05-10
Also published as: JP2007125987A; JP4540587B2

Abstract

Disclosed is a pneumatic tire for a two-wheeled vehicle, capable of improving response relative to steering angle and lightness of handling and of proving excellent steering stability during high-speed traveling by securing grip force during turning. The pneumatic tire (10) comprises bead cores (20), bead parts (18), a carcass (16), a diagonal belt layer (24) disposed on the tire radial outer side of the carcass, a spiral belt layer (22), and a tread rubber (30) forming a tread (28). In the lateral cross section of the tire, the center part of the tread (28) is formed of a tread rubber (30A) and both side-parts thereof are formed of tread rubbers (30B). The tread rubber (30A) is harder than the tread rubbers (30B), and boundaries between the tread rubber (30A) and the tread rubbers (30B) are formed in a ground contact surface when the rotating axis of the tire is positioned parallel with a road surface. As a result, the torsional rigidity of the center part can be increased, the lateral flexural rigidity of the both side-parts can be maintained in a low state, the response relative to steering angle and the lightness of handling can be improved and the steering stability during high-speed traveling can be increased since the grip force during turning can be secured.

Description

Specification

Pneumatic tires for motorcycles

Technical field

[0001] The present invention relates to a pneumatic tire for two-wheeled vehicles excellent in handling stability performance at high speeds, and in particular, a pneumatic tire for two-wheeled vehicles excellent in handling lightness and rudder angle response and gripping force during turning. About.

Background art

[0002] With the recent increase in speed of vehicles, as a required item for tires, it has become important to secure a high grip force that supports the vehicle when turning. In order to increase the grip force of the tire, a flexible compound rubber with a high grip force is applied to the tread rubber, or the tire width in the tire shoulder area (hereinafter simply referred to as the shoulder area) that contacts the road surface when turning. Techniques such as reducing the direction bending rigidity (hereinafter simply referred to as lateral bending rigidity), improving the flexibility, and increasing the ground contact are taken.

However, with these methods, the overall stiffness of the tire crown decreases, and the torsional rigidity of the tire crown decreases as the lateral bending rigidity of the shoulder region decreases. Angular response and lightness may be impaired, and safe driving may be hindered (steering stability may deteriorate).

[0003] On the other hand, in the tire disclosed in Japanese Patent Application Laid-Open No. 7-108805, the tread portion of the tire having a spiral belt structure is divided into three in the tire axial direction (the tread portion is divided into a central area and two side areas). The ratio of loss tangent to the JIS (A) hardness and dynamic complex modulus of the tread rubber in both sides is set higher than those in the center. This reinforces the low lateral rigidity of the snail structure and secures the grip force during turning, which improves cornering force and camber thrust and excels in turning performance.

Disclosure of the invention

[0004] However, when a stiffness step where the stiffness of the tread portion changes, for example, in the shoulder region, as in the tire of JP-A-7-108805, the camber ang during turning is provided. As a result, discontinuity will occur in the level of lateral force generated according to the vehicle, and the handling linearity may be impaired, and the steering stability performance at high speeds may be impaired.

[0005] In the factory, the tire tread stiffness distribution during high-speed driving is optimized, the grip force during turning is ensured, and the tire torsional rigidity is high and the steering angle response and nimbleness are excellent. Pneumatic tires for motorcycles are expected.

[0006] In consideration of the above facts, the object of the present invention is to improve the steering angle response and lightness of handling, as well as to secure a grip force during turning and to have excellent steering stability performance during high speed running. The object is to provide a pneumatic tire for a motorcycle.

[0007] In order to achieve the above object, a pneumatic tire for a motorcycle according to claim 1 of the present invention includes a bead core embedded in a pair of left and right bead portions, and a toroid shape from one bead portion to the other bead portion. A carcass having an end portion wound around the bead core and locked to the bead core and having a carcass ply force; a belt layer disposed on the outer side in the tire radial direction of the carcass; and the belt layer And a tread rubber that is disposed on the outer side in the tire radial direction and forms a tread portion that comes into contact with the road surface. In the tire width direction cross-section, the central portion of the tread portion is a first rubber. The both sides of the central portion are formed of a second rubber, and the boundary between the first rubber and the second rubber is harder than the second rubber. The tire rotation axis is provided in the ground contact surface when parallel to the road surface.

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

In order to improve the grip force when turning, as described above, by reducing the lateral bending rigidity of the shoulder area that touches down during turning, the flexibility of the shoulder area is improved and the grounding property is improved. There is a method to apply a flexible compound rubber with high grip strength to the tread rubber, but even if the grip strength is improved by any method, the torsional rigidity of the tire crown will decrease, rudder angle response and lightness The steering stability performance at high speeds will be poor.

[0009] Therefore, in the pneumatic tire for a motorcycle according to the present invention, the tread portion is the central portion and the side portions on both sides thereof, and the first rubber in the central portion is harder than the second rubber on the side portions on both sides. This improves the lateral bending rigidity and torsional rigidity at the center, and improves the steering angle response and lightness of Improves. At this time, since the lateral bending rigidity of the side portions on both sides is kept low, a high grip force is secured. As a result, the steering angle responsiveness and lightness during straight running are improved, and the grip force during turning is ensured.

[0010] Accordingly, the steering angle responsiveness and lightness are improved, the grip force at the time of turning is ensured, and the steering stability performance at high speed running is excellent.

[0011] Further, in the pneumatic tire for a motorcycle according to the present invention, the boundary between the first rubber and the second rubber is disposed in the ground contact surface when the tire rotation axis of the tread is parallel to the road surface. The discontinuity of the lateral force generation level corresponding to the camber angle at the time of turning due to the rigidity step between the first rubber and the second rubber is eliminated. For this reason, linearity of the ring and ring is ensured and the steering stability is excellent.

[0012] The contact surface in this claim refers to a tire contact surface when mounted on a normal rim, filled with a normal internal pressure, placed perpendicular to a flat plate in a stationary state, and a normal load is applied. This means that the distance in the tire axial direction of this contact surface is defined as the contact width.

“Regular rim” means, for example, a standard rim in the applicable size specified in the 2004 YEAR BOOK issued by JATMA. “Regular load” and “Regular internal pressure” are also issued by JATMA. Yes Applicable size specified in the 2004 YEAR BOOK • The maximum load in the ply rating and the air pressure for the maximum load. When the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the respective standards are followed.

[0013] A pneumatic tire for a motorcycle according to claim 2 of the present invention is the pneumatic tire for motorcycle according to claim 1, wherein, in the cross section in the tire width direction, the width of the ground contact surface is Wl, and the width of the center portion. When W2 is W2, it is characterized by satisfying 0.1W1≤W2.

Next, the function and effect of the pneumatic tire for a motorcycle according to claim 2 will be described. When 0.1W1> W2, the width W2 at the center is too narrow, and the torsional rigidity is less improved. Steering angle response and lightness are also less improved. Steering stability performance at high speeds is poor. . Therefore, the relationship between W1 and W2 is preferably 0.1W1≤W2, more preferably 0.5W1≤W2, and most preferably 0.8W1≤W2. The upper limit of W2 is less than W1 as defined in claim 1. [0015] A pneumatic tire for a motorcycle according to claim 3 of the present invention is the pneumatic tire for motorcycle according to claim 1 or 2, characterized in that the cord of the belt layer also has a steel force.

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

By making the belt layer cords steel, the overall rigidity of the tire is improved, and the steering angle response and lightness are also improved.

In particular, if the belt layer has a spiral belt structure, in addition to the grip strength due to the high grounding property due to the low lateral bending rigidity of the tire crown, which is a characteristic of the spiral belt, Since the torsional rigidity is improved by the dredge, the steering angle response and nimbleness are improved.

[0017] A pneumatic tire for a motorcycle according to claim 4 of the present invention is the pneumatic tire for a motorcycle according to any one of claims 1 to 3, wherein the belt layer includes one or a plurality of parallel belt layers. It is characterized by a spiral belt layer force formed by spirally winding a band-like body in which a book cord is embedded in a coated rubber.

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

Since the belt layer also has a spiral belt layer force, deformation (expansion) of the tire toward the outside in the tire radial direction during high-speed running is suppressed, and the ground contact shape is maintained, so that high-speed running durability is improved.

[0019] A pneumatic tire for a motorcycle according to claim 5 of the present invention is the pneumatic tire for motorcycle according to any one of claims 1 to 3, wherein the belt layer includes one or a plurality of parallel belt layers. It is provided between a spiral belt layer formed by spirally winding a belt-like body in which a cord is embedded in a coated rubber, and between the above-described snoral belt layer and the carcass, and is inclined with respect to the tire radial direction. It is characterized by a force with an inclined belt layer in which a plurality of extending cords are embedded in coated rubber.

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

Since the belt layer is composed of an inclined belt layer with a cord that is inclined with respect to the tire radial direction (perpendicular to the tire equatorial plane), lateral bending rigidity is ensured during turning, and a cornering force is generated. be able to. [0021] The pneumatic tire for a motorcycle according to claim 6 of the present invention is the pneumatic tire for a motorcycle according to any one of claims 1 to 3, wherein the belt layer includes one or a plurality of parallel tire layers. A spiral belt layer formed by spirally winding a strip of cords embedded in a coated rubber, and a plurality of belts provided between the snort belt layer and the carcass and arranged in parallel to each other. As a result, the belt ply force of a plurality of belts in which the cord is embedded in the covering rubber, and the cross belt layers in which the inclination directions of the cords with respect to the tire radial direction are opposite to each other between the belt plies adjacent to each other are also strong. It is characterized by that.

Next, functions and effects of the pneumatic tire for a motorcycle according to claim 6 will be described.

Since the belt layer is composed of a crossing belt layer having cords that are inclined with respect to the radial direction of the tire, lateral bending rigidity is ensured during turning, and a higher cornering force can be generated.

[0023] A pneumatic tire for a motorcycle according to claim 7 of the present invention is the pneumatic tire for motorcycle according to claim 5, wherein the angle B of the cord of the inclined belt layer with respect to the radial direction of the tire is 3 ° ≤ B It is characterized by satisfying ≤15 °.

Next, the function and effect of the pneumatic tire for a motorcycle according to claim 7 will be described. The reinforcement effect of the tire crown portion is improved by arranging an inclined belt layer having a cord whose angle with respect to the radial direction of the tire is B between the spiral belt layer and the carcass.

If B <3 °, the cord of the inclined belt layer is almost parallel to the radial direction of the tire, so the steering angle response and lightness are less improved, which has little effect on improving torsional rigidity. If B> 15 °, the lateral bending rigidity of the belt layer becomes too large, resulting in poor ground contact during turning and lower grip. Therefore, angle B is 3 ° ≤ B≤

It is preferable to satisfy 15 °.

[0025] A pneumatic tire for a motorcycle according to claim 8 of the present invention is the pneumatic tire for motorcycle according to claim 6, wherein the angle B of the cord of the crossing belt layer with respect to the tire radial direction is 3 ° ≤ B It is characterized by satisfying ≤15 °.

Next, the function and effect of the pneumatic tire for a motorcycle according to claim 8 will be described. The reinforcing effect of the tire crown portion is improved by arranging the crossing belt layer including the cord having an angle B with respect to the radial direction of the tire between the spiral belt layer and the carcass. At this time, if B <3 °, the cords of the crossing belt layers are almost parallel to the tire radial direction, so that the improvement in rudder angle response and nimbleness is small, which has little effect on improving torsional rigidity. . If B> 15 °, the lateral bending rigidity of the belt layer becomes too large, resulting in poor ground contact during turning and reduced grip. Therefore, the angle B preferably satisfies 3 ° ≤ B≤15 °.

[0027] A pneumatic tire for a motorcycle according to claim 9 of the present invention is the pneumatic tire for motorcycle according to any one of claims 1 to 8, wherein the elastic modulus of the first rubber is El, When the elastic modulus of the second rubber is E2, 1. 1≤E1 / E2≤1.7 is satisfied.

Next, functions and effects of the pneumatic tire for a motorcycle according to claim 9 will be described. 1.1> E1ZE2 results in little improvement in rudder angle response and lightness with little improvement in torsional rigidity at the center. Also, the turning force during turning is reduced. If E1 / E2> 1.7, the difference in the elastic ratio between the rubbers is too large, and the linearity of the handling is impaired, and the steering wheel may swing during driving. Therefore, it is preferable to satisfy 1.1≤E1 / E2≤1.7. In this specification, El and E2 are the elastic moduli when the rubber temperature is 60 ° C.

[0029] A pneumatic tire for a motorcycle according to claim 10 of the present invention is the pneumatic tire for a motorcycle according to claim 9, wherein the elastic modulus of the first rubber is El [kgfZmm ² ], the second tire. When the elastic modulus of rubber is E2 [kgfZmm ² ], it is characterized by satisfying 1 lkgf / mm ² ≤El≤ 16kgfZmm ² and 7 kgf / mm ² ≤E2≤13kgf Zmm ² .

Next, functions and effects of the pneumatic tire for a motorcycle according to claim 10 will be described.

If l lkgfZmm ^2> a El, for improving the torsional rigidity of the center portion is small, insufficient steering angle response and agility, if E1 rather 16KgfZmm ^2, the bending rigidity (the tire circumferential direction bending rigidity of the central portion And lateral bending rigidity) are excessively improved, vibration absorption is impaired, and ride performance is deteriorated.

Also, if 7kgf Zmm ² > E2, the lateral bending rigidity commensurate with the gripping force at the side during turning cannot be secured, so the turning force decreases and the turning performance decreases, and E2> 13kgf / mm ² If there is, the lateral bending rigidity of the side portion is too large, the grounding property at the time of turning is impaired, the grip force is lowered, and the steering stability performance is deteriorated. Therefore, the elastic modulus El fulfills l lkgfZmm ^² ≤El≤16kgfZmm ^2, also the elastic modulus E2 preferably satisfies the ^{7kgf / mm 2 ≤E2≤ 13kgf / mm} 2.

[0031] A pneumatic tire for a motorcycle according to claim 11 of the present invention is characterized in that the pneumatic tire for a motorcycle according to any one of claims 1 to 10 is used for a front wheel of a motorcycle.

Next, the function and effect of the pneumatic tire for a motorcycle according to claim 11 will be described.

With regard to nimbleness and steering angle response, in the case of a two-wheeled vehicle, the influence of the front wheel, which is a steering wheel, is large, so the pneumatic tire for a motorcycle described in any one of claims 1 to 10 is a front wheel of a motorcycle. The effect of improving the steering angle responsiveness and lightness of handling is increased.

[0033] The pneumatic tire for a motorcycle of the present invention improves the steering angle responsiveness and lightness of handling and secures a grip force at the time of turning, and has excellent steering stability performance at high speed running.

Brief Description of Drawings

FIG. 1 is a cross-sectional view taken along the rotation axis of a pneumatic tire for a motorcycle according to a first embodiment. FIG. 2 is taken along the rotation axis of a pneumatic tire for a motorcycle according to a second embodiment. FIG. 3 is a sectional view taken along the rotational axis of a pneumatic tire for a motorcycle according to a third embodiment.

[0035] 10 Pneumatic tire for motorcycles

16 Carcass

18 Bead section

20 Beadcore

22 Spiral belt layer

24 Inclined belt layer (belt layer)

26 Intersection belt layer 28 tread

30 tread rubber

30A Tread rubber 30A

30B Tread rubber 30B

BEST MODE FOR CARRYING OUT THE INVENTION

[0036] [First embodiment]

Next, a first embodiment of a pneumatic tire for a motorcycle according to the present invention will be described with reference to FIG. The pneumatic tire 10 for a motorcycle according to the present embodiment is a front tire, and the tire size is MCR180Z55ZR17MZC.

As shown in FIG. 1, the pneumatic tire 10 for a motorcycle includes a first force-and-force ply 12 and a second force-and-force 14 that have cords extending in a direction intersecting the tire equatorial plane CL. It has a carcass 16 constructed. 1 to 3, the carcass 16 is a single line, and the first carcass ply 12 and the second carcass ply 14 are not shown. In the present embodiment, the carcass 16 has a structure in which two carcass plies overlap each other. In other embodiments, the carcass 16 may have a structure having a single carcass ply force.

[0037] (Carcass)

Each of the first carcass ply 12 and the second carcass ply 14 is wound around the bead core 20 embedded in the bead portion 18 with the tire inner force also directed outward.

[0038] The first carcass ply 12 includes a plurality of radially extending cords (for example, organic fiber cords such as nylon) arranged in parallel in a covered rubber, and in the present embodiment, the tire equator The angle of the cord with respect to the tire radial direction on plane CL is set to 15 °. The second carcass ply 14 is also a cord in which a plurality of radially extending cords (for example, organic fiber cords such as nylon) are embedded in parallel in the covering rubber. In this embodiment, the tire equatorial plane CL The cord angle with respect to the tire radial direction is set to 15 °. In addition, the cord of the first carcass ply 12 and the cord of the second carcass ply 14 cross each other and are opposite to the tire equatorial plane CL. It is inclined in the direction. In the present embodiment, the first carcass ply 12 and the second carcass ply 14 use nylon cords.

[0039] (Inclined belt layer)

An inclined belt layer 24 is disposed outside the carcass 16 in the tire radial direction. The inclined belt layer 24 is formed from a belt ply 24A. In this embodiment, the belt ply 24A is formed by embedding a plurality of cords (corresponding to a 0.5 mm diameter twisted nylon fiber) in a coated rubber in parallel, and the tire radial at the tire equatorial plane CL. The code angle with respect to the direction is set to 10 °. Further, the cord driving density in the belt ply 24A in the present embodiment is 10 Z25 mm.

[0040] (Spiral belt layer)

A spiral belt layer 22 is provided outside the inclined belt layer 24 in the tire radial direction. The spiral belt layer 22 is, for example, a long rubber-coated cord in which one cord is coated with an unvulcanized coating rubber, or a belt-like ply in which a plurality of cords are coated with an unvulcanized coating rubber. It is formed by spirally winding, and the angle of the cord with respect to the tire equatorial plane CL is about 0 ° (about 0 to 3 °). In addition, the cord of the spiral belt layer 22 may be an organic fiber cord or a steel cord, and the spiral belt layer 22 of this embodiment has two parallel cords (steel having a diameter of 0.2 mm). It is formed by winding a strip of steel cord (1 x 2 type twisted steel cord) embedded in the covered rubber in a spiral shape around the tire rotation axis. The cord driving density in the spiral belt layer 22 of this embodiment is 37 Z25 mm. A spiral belt layer formed by spirally winding a long rubber-coated cord with one cord covered with unvulcanized coating rubber is called a monospiral belt layer.

[0041] (tread)

A tread rubber 30 that forms a tread 28 is disposed on the outer side of the radial belt layer 22 in the tire radial direction.

The tread rubber 30 is also formed with a plurality of types of rubber force. 30 is also formed with two types of rubber force, which will be described later. As seen from the cross section in the tire width direction, the tread rubber 30A is the center of the tread 28, the tread rubber 30A is the tread rubber 30B, and the tread rubber 30A is harder than the tread rubber 30B. From this, it can be said that the tread rubber 30A has higher rigidity than the tread rubber 30B.

The boundary between the tread rubber 30A and the tread rubber 30B on both sides is provided in the ground contact surface of the tire 10 (the ground contact surface when the tire rotation axis is parallel to the road surface).

[0042] Further, when viewed from the cross section in the tire width direction, when the contact width of the tread 28 is Wl and the width measured along the tire axis direction of the tread rubber 30A is W2, 0.1W1≤W2 is satisfied. Is preferred.

In addition, the angle B of the cord of the inclined belt layer 24 with respect to the tire radial direction is preferably 80 °, and the range of the force angle B satisfying 3 ° ≤ B ≤ 15 ° is satisfied in this embodiment.

[0043] When the elastic modulus of the tread rubber 30A is El [kgfZmm ² ] and the elastic modulus of the tread rubber 30B is E2 [kgfZ mm ² ], it is preferable that 1.1≤E1 / E2≤1.7 is satisfied.

Moreover, El [kgfZmm ^2] in the range l lkgfZmm ^² ≤El≤ 16kgfZmm ² range is preferred instrument E2kgfZmm ² to meet, it is preferable to satisfy the 7kgfZmm ^² ≤E2≤ 13kgfZmm ^2.

[0044] (Function)

In the pneumatic tire 10 for a motorcycle according to this embodiment, since the spiral belt layer 22 is provided on the outer side in the tire radial direction of the carcass 16, the rigidity in the tire circumferential direction of the tread 28 is increased, and the tire of the tread 28 during high-speed traveling is increased. The protrusion to the outside in the radial direction can be suppressed, and the high-speed durability is improved. In addition, by providing the inclined belt layer 24, the lateral bending rigidity is improved, and a cornering force can be generated at the time of turning.

Furthermore, in the pneumatic tire 10 for a motorcycle according to the present embodiment, the tread 28 is formed by the tread rubber 30 A and the tread rubber 30 B, and the boundary between the tread rubber 30 A and the tread rubber 30 B is formed in the ground contact surface of the tread 28. Further, when the tread rubber 30A is harder than the tread rubber 30B, the lateral bending rigidity and torsional rigidity of the central portion are improved. Also, the lateral bending rigidity of both sides is kept low. As a result, the steering angle responsiveness and lightness when traveling straight ahead are improved, and the grip force during turning is ensured. Therefore, rudder angle Responsiveness and nimbleness are improved, and grip power during turning is ensured, resulting in excellent handling stability at high speeds.

[0046] Further, since the rigid step force between the tread rubber 30A and the tread rubber 30B is arranged in the ground plane, the discontinuity in the generation level of the lateral force corresponding to the CA change during turning is eliminated, and the handling The linearity is ensured and the steering stability is excellent.

[0047] If 0.1W1> W2, the width W2 of the tread rubber 30A is too narrow, so the steering angle response and lightness improvement with little improvement in torsional rigidity at the center part and maneuvering at high speeds with little improvement. Stability performance deteriorates. Therefore, it is preferable that the relationship between W1 and W2 satisfies 0.1W1≤W2. The upper limit of W2 is less than W1 as defined in claim 1.

[0048] Further, by making the cord of the spiral belt layer 22 made of steel, the grip force resulting from the high grounding property due to the low lateral bending rigidity of the tire crown portion and the cord of the spiral belt layer 22 were steeled. This improves the torsional rigidity and improves the steering angle response and lightness.

[0049] Further, the reinforcing effect of the tire 10 is improved by disposing the inclined belt layer 24 having a cord having an angular force with respect to the radial direction of the tire between the spiral belt layer 22 and the carcass 16.

At this time, if B <3 °, the cord of the inclined belt layer 24 is substantially parallel to the tire radial direction, so that the improvement in rudder angle responsiveness and lightness with little effect on torsional rigidity is small. Also, if B> 15 °, the lateral bending rigidity of the belt layer becomes too large, resulting in poor grounding performance during turning and reduced grip. Therefore, the angle B preferably satisfies 3 ° ≤ B≤15 °.

[0050] In addition, when 1.1> E1ZE2, the improvement in rudder angle response and lightness with little improvement in torsional rigidity at the center is small, and the grip force during turning is also small. If El / E2> 1.7, there is a possibility that the linearity of the ring and ring will be impaired because the difference in the modulus of elasticity between the rubbers is too large. Therefore, it is preferable to satisfy 1.1≤E1 / E2≤1.7.

If ^{[0051] l lkgfZmm 2> El} , for improving the torsional rigidity of the center portion is small, insufficient steering angle responsiveness and agility, if E1 rather 16KgfZmm ^2, the central portion of the flexural rigidity (Thailand The circumferential bending rigidity and lateral bending rigidity) are excessively improved and vibration absorption is impaired. The ride performance will be poor.

In addition, if 7kgfZmm ² > E2, the lateral bending rigidity commensurate with the grip force on both sides during turning cannot be ensured and the turning performance will be degraded.If E2> 13kgfZmm ² , the lateral bending rigidity is too large, The grounding ability is impaired, the gripping power is reduced, and the steering stability performance when turning is deteriorated. Accordingly, the elastic modulus E1 preferably satisfies l lkgfZmm ² ≤El≤16kgfZm m ² , and the elastic modulus E2 preferably satisfies 7 kgfZmm ² ≤E2≤13kgfZmm ² .

[0052] Further, by using the tire 10 for the front wheels, the steering angle response and lightness of the handling performance are improved, the grip force at the time of turning is ensured, and the steering stability performance at the time of high speed running is excellent.

[0053] In this embodiment, the belt ply 24A is made of nylon fiber as the cord. In other embodiments, the material of these cords may be aromatic polyamide fiber (for example, Kepler: registered trademark). .

[0054] [Second Embodiment]

Next, a second embodiment of the pneumatic tire for a motorcycle according to the present invention will be described with reference to FIG. Note that the tire size of the pneumatic tire 10 for a motorcycle according to the present embodiment is MCR180Z55ZR17MZC as in the first embodiment. As shown in FIG. 2, the pneumatic tire 10 for a motorcycle differs from the first embodiment in that an intersecting belt layer 26 is arranged instead of the inclined belt layer 24, and the other is the first implementation. It is the structure similar to a form. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[0055] (Intersection belt layer)

The cross belt layer 26 includes a first belt ply 26A and a second belt ply 26B.

[0056] In the present embodiment, the first belt ply 26A is a tire in which a plurality of cords (corresponding to a diameter of 0.5 mm formed by twisting nylon fibers) are arranged in parallel in a covered rubber, and are embedded in a tire. The cord angle with respect to the radial direction of the tire on the equatorial plane CL is set to 10 °. The second belt ply 26B is also formed by embedding a plurality of cords (corresponding to a 0.5 mm diameter twisted nylon fiber) in the covered rubber, parallel to the tire equatorial plane CL. The angle of the cord with respect to the radial direction is set to 10 °!

[0057] It should be noted that the cord of the first belt ply 26A and the cord of the second belt ply 26B cross each other and incline in opposite directions with respect to the tire equatorial plane CL. In addition, the cord driving density in each of the first belt ply 26A and the second belt ply 26B in this embodiment is 37 Z25mm.

[0058] (Function)

In the pneumatic tire 10 for a motorcycle according to the present embodiment, in addition to the effects of the first embodiment, the cord of the crossing belt layer 26 and the steel cord of the spiral belt layer 22 intersect with each other. Torsional rigidity and lateral bending rigidity are further improved. Therefore, the steering angle responsiveness and nimbleness of handling are improved, and the steering stability is improved because the feeling of rigidity during turning is increased.

[0059] In the present embodiment, a force in which the cord of the first belt ply 26A and the cord of the second belt ply 26B are made of nylon fibers. In other embodiments, the material of these cords is an aromatic polyamide fiber. (For example, Kepler)

[0060] [Third embodiment]

Next, a third embodiment of the pneumatic tire for a motorcycle of the present invention will be described with reference to FIG. Note that the tire size of the pneumatic tire 10 for motorcycles of the present embodiment (hereinafter simply referred to as tire 10) is MCR180Z55ZR17MZC as in the first embodiment. In the tire 10, as shown in FIG. 3, the tread rubber 30A tapers from the tread 28 tread side toward the tread 28 bottom side, and the boundary force between the tread rubber 30A and the tread rubber 30B is connected to the bottom surface of the tread 28. ing. Specifically, the tread rubber 30A has an inverted triangle shape when viewed from the cross section in the tire width direction. This is different from the first embodiment, and the other configuration is the same as that of the first embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[0061] (Function)

In order for the boundary between the tread rubber 30A and the tread rubber 30B to be connected at the bottom surface of the tread 28, the boundary between the rubber viewed from the cross section in the tire width direction is closer to the tire equatorial surface from the tread tread side to the tread bottom side. It is necessary to. In other words, the boundary is slanted There is a need. As a result, the rigidity step at the tread tread boundary can be reduced and the handling linearity can be improved.

[0062] (Test example)

In order to confirm the performance improvement effect of the pneumatic tire for motorcycles of the present invention, five types of pneumatic tires for motorcycles of examples according to the first embodiment of the present invention, three types of pneumatic tires for motorcycles of comparative examples, In addition, we prepared one type of pneumatic tire for motorcycles of a conventional example and conducted a longitudinal stability comparison test using an actual vehicle. These two-wheeled pneumatic tires (hereinafter simply referred to as tires) were mounted on the front, and conventional tires were mounted on the rear for actual vehicle tests. The evaluation method is as follows.

[0063] In the test, the test tire was mounted on a lOOOOcc sports type motorcycle, and the vehicle was run on the test course, and the lightness, turning force and handling included in the handling stability were evaluated by the feeling of the test rider. The evaluation results are shown in Table 1 as index indications when the steering stability performance of tires of the conventional spiral belt structure is taken as 100. The larger the evaluation value, the better the result.

[0064] The size of the test tire is MCR180Z55ZR17MZC. This tire is mounted on the rim MT 5.5 X 17, and the tire is pressurized until the internal pressure becomes 250 kPa.

The tire of the conventional example was of the same size, the same rim, and the same pressure as the test tire except that it was composed of one kind of tread rubber and only a spiral belt.

[0065] [Table 1]

From the results shown in Table 1, it can be seen that the tires of Examples 1 to 5 are superior to the tires of Comparative Examples 1 to 3 and the conventional example in lightness and turning ability. Therefore, the tires of Examples 1 to 5 It can be seen that the steering stability performance at high speeds is superior to the tires of Comparative Examples 1 to 3 and the conventional example.

Industrial applicability

The present invention can be applied to the industrial field of pneumatic tires for motorcycles.

Claims

The scope of the claims

[1] a bead core embedded in a pair of left and right bead portions;

One bead portion force The other bead portion straddles a toroid, the end portion is wound around the bead core, and the car force ply force is at least one carcass ply force that is locked to the bead core;

A belt layer disposed on the outer side in the tire radial direction of the carcass;

A pneumatic tire for a motorcycle comprising: a tread rubber disposed outside the belt layer in a tire radial direction and forming a tread portion that contacts a road surface;

In the cross section in the tire width direction, a central portion of the tread portion is formed of a first rubber, side portions on both sides of the central portion are formed of a second rubber, and the first rubber is the second rubber. A pneumatic tire for a motorcycle, wherein the harder boundary between the first rubber and the second rubber is disposed within a contact surface when the tire rotation axis is parallel to the road surface.

[2] The motorcycle air according to claim 1, wherein, in the cross section in the tire width direction, 0.1W1≤W2 is satisfied, where W1 is a width of the ground contact surface and W2 is a width of the central portion. Entered tire.

[3] The pneumatic tire for a motorcycle according to claim 1 or 2, wherein the cord of the belt layer has a steel force.

[4] The belt layer comprises a spiral belt layer formed by spirally winding a belt-like body in which one or a plurality of parallel cords are embedded in a covering rubber. The pneumatic tire for a motorcycle according to any one of 1 to 3.

[5] The belt layer includes a spiral belt layer formed by spirally winding a belt-like body in which one or a plurality of parallel cords are embedded in a coating rubber, the spiral belt layer, and the carcass And an inclined belt layer in which a plurality of cords extending obliquely with respect to the radial direction of the tire are embedded in the covering rubber. The pneumatic tire for a motorcycle according to item 1.

[6] The belt layer includes a spiral belt layer formed by spirally winding a belt-like body in which one or a plurality of parallel cords are embedded in a covering rubber, the spiral belt layer, and the carcass A plurality of cords arranged between and parallel to each other in the coated rubber 2. A cross belt layer comprising a plurality of belt pliers embedded in the belt, wherein the belt plies adjacent to each other have mutually opposite inclination directions with respect to the tire radial direction of the cord. The pneumatic tire for a motorcycle according to any one of items 1 to 3.

[7] The pneumatic tire for a motorcycle according to claim 5, wherein an angle B of the cord of the inclined belt layer with respect to a tire radial direction satisfies 3 ° ≤ B ≤ 15 °.

[8] The pneumatic tire for a motorcycle according to claim 6, wherein an angle B of the cord of the crossing belt layer with respect to a tire radial direction satisfies 3 ° ≤ B ≤ 15 °.

[9] When the elastic modulus of the first rubber is El and the elastic modulus of the second rubber is E2, 1. 1≤E1

The pneumatic tire for a motorcycle according to any one of claims 1 to 8, wherein /E2≤l.7 is satisfied.

[10] When the elastic modulus of the first rubber is El [kgfZmm ² ] and the elastic modulus of the second rubber is E2 [kgfZm m ² ], l lkgf / mm ² ≤E1≤ 16 kgf / mm ² and The pneumatic tire for a motorcycle according to claim 9, wherein 7kgf / mm ² ≤ E2 ≤ 13kgf Zmm ² is satisfied.

[11] The pneumatic tire for a motorcycle according to any one of claims 1 to 10, wherein the pneumatic tire is used for a front wheel of a motorcycle.