JP5635172B2 - Pneumatic tires for motorcycles - Google Patents

Description

  The present invention relates to a pneumatic tire for a motorcycle (hereinafter, also simply referred to as “tire”), and more particularly, to improve high-speed durability and ride comfort, and in particular, traction when accelerating from deep cornering that greatly tilts the vehicle body. The present invention relates to a pneumatic tire for a motorcycle that can improve the performance.

  In high-performance two-wheeled vehicle tires, the rotational speed of the tires is high, and therefore the influence of centrifugal force is large, and the tread portion of the tires expands outward, which may impair steering stability. For this reason, a tire structure has been developed in which a reinforcing member (spiral member) made of organic fiber or steel is wound around the tread portion of the tire so as to be substantially parallel to the tire equatorial plane. Nylon fiber, aromatic polyamide (aramid), steel, or the like is used as a reinforcing member wound in a spiral shape along the tire equator plane. Among them, aromatic polyamide and steel can suppress the expansion of the tread portion without stretching even at high temperatures, so that even when the tire rotates at high speed, the tire does not swell due to centrifugal force. Durability can be improved.

For example, Patent Document 1 discloses a motorcycle tire using a steel cord formed by bundling a plurality of steel wires spirally formed at the same pitch without being twisted in the same phase as a spiral belt layer. This steel cord does not twist the shaped filaments, so that it does not contain rubber inside the steel cord, and it is possible to maintain the initial elongation like a spring by shaping even after vulcanization. Further, in Patent Document 2, the spiral belt layer is composed of a rubber-steel cord composite in which a steel cord composed of a plurality of steel linear bodies is embedded in rubber, and the rubber adheres within a circumscribed circle of the steel cord. In the strain-load characteristics in a state where the steel cord has a cross-sectional area of steel part of S, the elongation when the load W is changed from 1500 × S to 1600 × S is 0.070% or less. , and the applied load _{W 2} of elongation applied load _{W 1} of 0.45% elongation at _{0.35%, W 2 -W 1 <} 35 · S pneumatic radial tire for a motorcycle that satisfies is disclosed Yes.

  It is known that a tire around which such a spiral member is wound has excellent steering stability at high speed and extremely high traction. However, the ride comfort when going straight does not improve because the spiral member is wound. Therefore, it is desired to improve both the ride comfort when traveling straight ahead and the traction when the vehicle is largely defeated.

JP 2007-302033 A JP 2007-191096 A

  As described above, a pneumatic tire for a motorcycle is known in which a spiral belt layer formed by winding a cord in the circumferential direction is arranged on the outer side in the radial direction of the radial carcass. As a material for the cord forming the spiral belt, a material having high tension is used in order to suppress circumferential extension of the tread portion generated by centrifugal force during high-speed traveling. Specifically, a steel cord or a high cord is used. It is also known that a spiral belt is formed by winding any one of elastic organic fiber cords over the entire width of the spiral belt.

  When a steel cord is used as the cord for the spiral belt, the effect of suppressing the radial expansion of the tread portion is high, which can contribute to improvement in high-speed durability and straight running stability. However, it is difficult to follow the unevenness of the road surface flexibly due to its high rigidity, and it is difficult to respond even if a higher ride comfort is required.

  In addition, when a highly elastic organic fiber cord is used as the cord for the spiral belt, there is no particular problem if it is running at low speed. It will be unsatisfactory.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a pneumatic tire for a motorcycle that can improve high-speed durability and ride comfort, and in particular, can improve traction when accelerating from deep cornering that greatly depresses the vehicle body. It is in.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that the above-mentioned problems can be solved by adopting the following configuration, and has completed the present invention.

That is, the pneumatic tire for a motorcycle according to the present invention includes a tread portion, a pair of sidewall portions disposed radially inward from both edges of the tread portion, and a radially inner side of the sidewall portion. And at least one layer of carcass ply in which each part is reinforced between bead cores embedded in the bead part and the cord forming 60 to 90 ° with respect to the tire equatorial plane is covered with rubber. And a spiral having a width 0.8 to 1.1 times that of the tread portion formed on the outer side in the tire radial direction of the carcass layer and spirally formed substantially parallel to the tire equatorial plane. In a pneumatic tire for a motorcycle having a belt layer,
The spiral belt layer is composed of a rubber-steel cord composite in which a steel cord is embedded in rubber, and is divided into a central region and three regions on both sides of the central region, and the center The steel cord embedded in the both side regions is more elastic than the steel cord embedded in the rubber of the partial region,
The steel cord of the central region is bundled without twisting a plurality of steel wire bodies molded at substantially the same pitch at substantially the same phase, and is spiral-shaped,
The steel wire is a steel filament;
The steel cords in the both side regions are formed by twisting a plurality of steel wire bodies spirally formed at substantially the same pitch at substantially the same phase,
The steel cord embedded in the rubber in the both side regions has a 0.35% elongation when the cross-sectional area of the steel portion of the steel cord is S (mm ² ) in the strain-load characteristics when the rubber is adhered. Load load W1 (N) and load load W2 (N) at 0.45% elongation
(W2-W1) / S> 100
Satisfying the relationship represented by
When the steel cord embedded in the rubber in the central region has a strain-load characteristic when the rubber is attached, the steel cord cross-sectional area is S (mm ² ), and the steel cord has an elongation of 0.35%. Load load W1 (N) and load load W2 (N) at 0.45% elongation
(W2-W1) / S <35
Satisfied,
The amount of elongation when the load W is changed from 1500 × S (N) to 1600 × S (N) is 0.065% or less.

  In the present invention, the tire's ground contact width is the flat plate of the tire when a load corresponding to the maximum load capacity is applied by mounting the tire on the applicable rim, filling the specified air pressure, and statically placing it on the flat plate in a vertical posture. When the maximum width of the contact surface is set, the width of the central region is preferably 70 to 130% of the ground contact width.

  ADVANTAGE OF THE INVENTION According to this invention, while improving high-speed durability and riding comfort, the pneumatic tire for motorcycles which can improve the traction property especially when accelerating from the time of the deep cornering which greatly falls a vehicle body can be provided. .

1 is a schematic cross-sectional view showing a pneumatic tire for a motorcycle according to the present invention. It is the top view seen from the tire radial direction outer side which shows the structure of the spiral belt which concerns on this invention. It is sectional drawing of a 1 * 5 twisted cord. It is sectional drawing of a 1x2 twisted cord. It is sectional drawing of a 1 * 5 spiral shaping code.

DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a schematic cross-sectional view of an example of a pneumatic tire for a motorcycle according to the present invention. As shown in the drawing, the tire of the present invention includes a tread portion 1, a pair of sidewall portions 2 disposed on the inner side in the tire radial direction from both edge portions of the tread portion 1, and an inner side in the tire radial direction of the sidewall portion 2. And a bead portion 3 that is connected to the bead. Further, at least one layer (in the illustrated example, two layers) in which each of these parts is reinforced between the bead cores 4 embedded in the bead part 3 and the cord forming 60 to 90 ° with respect to the tire equatorial plane is covered with rubber. ) Of the carcass ply, and the carcass layer 5 is spirally formed on the outer side in the tire radial direction of the carcass layer 5 substantially in parallel with the tire equatorial plane, and the width is 0.8 to 1.1 of the tread portion. A double spiral belt layer 6 is provided.

  FIG. 2 is a plan view of the carcass layer 5 and the spiral belt layer 6 when viewed from the outer side in the tire radial direction. In the present invention, the spiral belt layer 6 is made of a rubber-steel cord composite, and as shown in the figure, the spiral belt layer is divided into three regions, a central region 7 and both side regions 8. It is important that the steel cords embedded in the side region 8 have higher elasticity than the steel cord embedded in 7.

  By lowering the elastic modulus of the steel cord in the central region 7, vibrations caused by road surface unevenness can be absorbed during straight traveling, and riding comfort performance can be improved. In addition, by increasing the elastic modulus of the steel cords on both side regions 8, after cornering with a large camber angle, improve the traction performance when raising the speed by raising the vehicle body and improving the steering stability performance Can do. The latter, unlike the lateral grip performance when cornering with a large camber angle, increases the circumferential rigidity and generates a large circumferential traction force.

  As a preferred means for making the steel cords embedded in the side region 8 more elastic than the steel cords embedded in the rubber in the central region 7, the steel cords in the central region 7 have substantially the same pitch. For example, a steel cord that is formed by bundling a plurality of steel wire bodies shaped in the above without being twisted in substantially the same phase and spirally shaping may be used. In this case, the steel cord embedded in the rubber in the side region 8 may be a twisted cord. Preferably, a plurality of steel wire bodies spirally formed at substantially the same pitch are substantially the same. Twisted in phase. Thus, the most efficient method is to dispose the spiral belt layer 6 with the tension (tensile force) in the central region 7 smaller than that in the side regions 8.

  Further, as another preferred means for making the steel cord embedded in the side region 8 more elastic than the steel cord embedded in the rubber in the central region 7, the amount of helical cording of the steel cord in the central region 7 is as follows. There can be mentioned means for making the steel cord larger than the amount of the steel cord spirally formed in both side regions 8, and the intended purpose can be achieved even if such means is adopted.

  In the present invention, the steel cord of the central region 7 is bundled without twisting a plurality of steel wire bodies molded at substantially the same pitch at substantially the same phase, and is spiral-shaped. The steel wire is a steel filament.

  That is, when a steel cord is made by twisting steel wire bodies, in the initial stage when there is a gap between filaments when a tensile load is applied, twisting shows low rigidity like a spring, and the load is When the gap between them increases and the gap disappears, the rigidity suddenly increases, but when embedded in rubber and vulcanized, the volume of rubber inside the cord hardly changes, so there is a gap. However, it becomes impossible to squeeze and twist, so that it shows high rigidity from the beginning. However, by not twisting together as described above, it is possible to have a spring-like elongation even after vulcanization by allowing the rubber to escape outside the cord without confining it inside the cord. The above characteristic is a characteristic when the steel wire is bundled, and the method of molding may be either spiral type or in-plane type.

As the elastic modulus, specifically, the steel cord embedded in the rubber in the both side regions 8 has a cross-sectional area S (mm ² ) of the steel cord in the strain-load characteristic when the rubber is adhered. The load load W1 (N) at 0.35% elongation and the load load W2 (N) at 0.45% elongation are expressed by the following equations:
(W2-W1) / S> 100
Satisfying the relationship represented by
When the steel cord embedded in the rubber in the central region 7 is strain-load characteristics when the rubber is adhered, when the cross-sectional area of the steel portion of the steel cord is S (mm ² ), when the steel cord is stretched 0.35% Load load W1 (N) and load load W2 (N) at 0.45% elongation are given by the following formula:
(W2-W1) / S <35
The elongation amount when the load W is changed from 1500 × S (N) to 1600 × S (N) is preferably 0.065% or less.

  When the strain-load characteristic of the steel cord wound around the both side regions 8 is (W2−W1) / S ≦ 100, the elastic modulus is the same as that of the high-elasticity organic fiber, and the lateral force is reduced. The steering stability will be reduced. On the other hand, when the strain-load characteristic of the steel cord wound around the central region 7 is (W2−W1) / S ≧ 35, the elastic modulus is too high, road surface followability deteriorates, and riding comfort deteriorates. End up. Further, if the elongation when the load W applied to the steel cord wound around the central region 7 is changed from 1500 × S (N) to 1600 × S (N) exceeds 0.065%, the circumferential rigidity Becomes too low, and high-speed durability cannot be secured sufficiently.

  As a method for stably and efficiently producing such a rubber-steel cord composite, for example, a plurality of the steel wire bodies wound on separate reels are bundled through a single base to form a steel cord. This steel cord is coated with rubber and then embedded in a rubber composite, or a plurality of steel wires wound on separate reels are bundled through one slit to form a steel cord. It is useful to use a method in which rubber is pressed against the cord from above and below and then the steel cord is embedded in a rubber composite.

  Further, in the present invention, the tire has a ground contact width when the tire is mounted on an applicable rim, filled with a specified air pressure, placed stationary on a flat plate in a vertical posture, and a load corresponding to the maximum load capacity is applied. When the maximum width of the contact surface to the flat plate is set, the width of the central region 7 is preferably 70 to 130% of the ground contact width. When the central region 7 is less than 70% of the contact width, the elastic modulus of the spiral belt layer 6 existing in the contact surface during straight traveling becomes high, and the riding comfort deteriorates. If it exceeds 130% of the ground contact width, the elastic modulus of the spiral belt layer 6 existing in the ground contact surface at the time of turning becomes too low, and the steering stability at the time of turning is lowered.

  Here, the “contact width” is the contact width at the maximum load (maximum load capacity) of a single wheel in the application size described in the following standard, and the internal pressure is the application described in the following standard. It is the air pressure for the maximum load (maximum load capacity) of a single wheel in size, and the rim is a standard rim (or “Approved Rim”, “Recommended Rim”) in the applicable size described in the following standards.

  Here, the standard is a standard determined by an industrial standard effective in an area where a tire is produced or used. For example, “Year Book of The Tire and Rim Association Inc.” in the United States, “Standards Manual of The European Tire and Rim Technical Organization” in Europe, and “JATMAYear Book” of the Japan Automobile Tire Association in Japan. Yes.

  As long as the pneumatic tire for motorcycles of the present invention satisfies the conditions relating to the structure of the spiral belt layer, other specific cord structures, the number and diameters of steel wire bodies, and specific structures The material of steel and rubber is not particularly limited. Further, the tire structure other than that, the material of each component, and the like are not particularly limited.

Hereinafter, the present invention will be described in more detail with reference to examples.
(Examples and Comparative Examples 1 to 3)
A pneumatic tire for a motorcycle having the cross-sectional structure shown in FIG. The tire size was 190 / 50ZR17, the rim size was MT6.00 × 17 inches, the internal pressure was 290 kPa, and each test tire was mounted as a rear tire. After that, we evaluated each of high-speed durability, ride comfort when going straight, and steering stability when cornering. In addition, the code | cord | chord sectional drawing of the spiral belt layer which concerns on an Example and Comparative Examples 1-3 is shown to FIGS.

<Ride comfort when driving straight and steering stability when cornering>
A rider's feeling evaluation was performed on the ride comfort during straight running and the steering stability during corner turning. The results are shown as an index with Comparative Example 1 as 100. In any case, the larger the value, the better the performance and the better the result.

<High speed durability>
Evaluation was made by a drum test in which a rotating drum was regarded as a road surface. The load condition was 1750N, the speed was increased from 180 km / h to 10 km / h as one step, the speed was increased by one step every 10 minutes, and the evaluation was made according to which step the tire bursts. The results are shown as an index with Comparative Example 1 as 100. The larger this value, the better the durability and the better the result.

  From Table 1 above, it can be seen that the tire of the present invention is superior in high-speed durability, straight-line riding comfort, and cornering steering stability compared to the comparative tire.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Bead core 5 Carcass layer 6 Spiral belt layer 7 Center area 8 Both sides area

Claims (2)

A tread portion, a pair of sidewall portions disposed on the inner side in the tire radial direction from both edges of the tread portion, and a bead portion continuous on the inner side in the tire radial direction of the sidewall portion. A carcass layer comprising at least one carcass ply in which a cord forming 60 to 90 ° with respect to the tire equatorial plane and covered with rubber is reinforced between the bead cores embedded in the tire, and the tire radial direction of the carcass layer A pneumatic tire for a motorcycle having a spiral belt layer formed on the outer side and spirally wound substantially parallel to the tire equatorial plane and having a width of 0.8 to 1.1 times that of the tread portion. In
The spiral belt layer is composed of a rubber-steel cord composite in which a steel cord is embedded in rubber, and is divided into a central region and three regions on both sides of the central region, and the center The steel cord embedded in the both side regions is more elastic than the steel cord embedded in the rubber of the partial region,
The steel cord of the central region is bundled without twisting a plurality of steel wire bodies molded at substantially the same pitch at substantially the same phase, and is spiral-shaped,
The steel wire is a steel filament;
The steel cords in the both side regions are formed by twisting a plurality of steel wire bodies spirally formed at substantially the same pitch at substantially the same phase,
The steel cord embedded in the rubber in the both side regions has a 0.35% elongation when the cross-sectional area of the steel portion of the steel cord is S (mm ² ) in the strain-load characteristics when the rubber is adhered. Load load W1 (N) and load load W2 (N) at 0.45% elongation
(W2-W1) / S> 100
Satisfying the relationship represented by
When the steel cord embedded in the rubber in the central region has a strain-load characteristic when the rubber is attached, the steel cord cross-sectional area is S (mm ² ), and the steel cord has an elongation of 0.35%. Load load W1 (N) and load load W2 (N) at 0.45% elongation
(W2-W1) / S <35
Satisfied,
A pneumatic tire for a motorcycle, wherein an elongation amount when the load W is changed from 1500 × S (N) to 1600 × S (N) is 0.065% or less. The contact width of the tire is measured when the tire is mounted on the applicable rim, filled with the specified air pressure, placed stationary on the flat plate in a vertical position, and when the load corresponding to the maximum load capacity is applied. The pneumatic tire for a motorcycle according to claim 1, wherein the width of the central region is 70 to 130% of the contact width when the maximum width is set.

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