JP2014061891A - Pneumatic tire for two-wheeled motor vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire for a two-wheeled motor vehicle, which improves steering stability performance and durability at high speed, and particularly, which can improve traction performance upon acceleration after sharp cornering with a vehicle body greatly inclined and can improve stability when the vehicle body is inclined.SOLUTION: A pneumatic tire for a two-wheeled motor vehicle comprises a spiral belt layer having a width 0.8 to 1.1 times that of a tread part 1. A spiral belt layer 6 includes a rubber-steel cord composite. The spiral belt layer 6 is divided into three regions of a central part region 7 and both side part regions 8. A steel cord embedded in each side part region 8 is less elastic than a steel cord embedded in the central part region 7. The steel cord in each side part region 8 is formed by bundling a plurality of steel linear elements shaped substantially in the same pitch, without twisting approximately in the same phase, and by spirally shaping them. The steel linear elements are steel filaments.

Description

  The present invention relates to a pneumatic tire for a motorcycle (hereinafter, also simply referred to as “tire”), and more particularly, to improve handling stability and durability at high speeds, and particularly when accelerating from a deep cornering that greatly defeats a vehicle body. The present invention relates to a pneumatic tire for a motorcycle that can improve the traction performance of the vehicle and the stability when the vehicle body is lowered.

  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.

  It is known that a tire wound with such a spiral member has excellent steering stability when traveling straight at high speed and has very high traction. However, with regard to the turning performance when the vehicle is largely tilted, the steering stability performance is not dramatically improved just because the spiral member is wound. Therefore, it is desired to improve the grip force when the vehicle is largely defeated.

  It is also known that the durability performance at high speed is particularly improved by increasing the elastic modulus of the spiral member. In general, when a spiral member having a high elastic modulus is used for a spiral belt, centrifugal expansion of a tread portion of a tire can be suppressed, and durability performance at high speed is improved. In the case of a motorcycle tire, since the central region of the tread used at high speed receives a large centrifugal force, it is effective to use a spiral member having a high elastic modulus in order to prevent centrifugal expansion. On the other hand, the tread side regions that contact the ground when the vehicle is largely tilted may use a spiral member having an elastic modulus lower than that of the central region, and attach importance to grounding stability. As described above, in the tire, since the performance required for the center region and the both side regions of the tread is different, a technique for changing the elastic modulus of the spiral member within the tread arrangement portion has also been proposed (for example, Patent Document 2, 3).

JP 2007-302033 A Japanese Patent Laid-Open No. 03-128703 European Patent No. 0978396

  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, when turning the vehicle by largely tilting it, the grounding becomes unstable due to the high rigidity in the circumferential direction, and the slip in the tire rotating direction is large, resulting in a decrease in steering stability during turning. The problem arises. On the other hand, when a highly elastic organic fiber cord is used as the cord for the spiral belt, there is no particular problem at low speeds, but when higher speed performance is required, high speed durability and straight running stability It becomes unsatisfactory in terms of sex.

  Therefore, an object of the present invention is to improve the steering stability performance and durability at high speeds, and in particular, to improve the traction performance when accelerating from deep cornering that greatly collapses the vehicle body and the stability when the vehicle body is collapsed. The object is to provide a pneumatic tire for a motorcycle.

  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 cords embedded in the both side regions are less elastic than the steel cords embedded in the rubber of the partial region,
The steel cords of the both side regions are bundled without twisting a plurality of steel wire bodies that are molded at substantially the same pitch at substantially the same phase, and are spirally molded,
The steel wire is a steel filament;
The steel cord embedded in the rubber in the central region has a 0.5% elongation when the cross-sectional area of the steel portion of the steel cord is S (mm ² ) in the strain-load characteristics with the rubber attached. Load load W1 (N) and load load W2 (N) at 1.0% elongation
(W2-W1) / S> 100
Satisfying the relationship represented by
The steel cords embedded in the rubber in the both side regions are stretched by 0.5% when the cross-sectional area of the steel part 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 1.0% elongation
(W2-W1) / S <50
It is characterized by satisfying the relationship represented by

  In the present invention, the steel cord in the central region is preferably formed by twisting a plurality of steel wire bodies spirally formed at substantially the same pitch in substantially the same phase. The maximum width of the contact surface to 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 placing it stationary on the flat plate in a vertical posture In this case, the width of the central region is preferably 70 to 130% of the ground contact width.

  According to the present invention, a motorcycle capable of improving steering stability performance and durability at a high speed, and improving traction performance especially when accelerating from deep cornering that greatly collapses the vehicle body and stability when the vehicle body is collapsed. A pneumatic tire 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 to make the steel cords embedded in the both side regions 8 have lower elasticity than the steel cord embedded in 7.

  If the circumferential rigidity of the central region 7 is insufficient, deformation that grows in diameter due to centrifugal force when the central region 7 is grounded and travels at a high speed increases, and high-speed durability and high-speed straightness deteriorate. End up. On the other hand, when the circumferential rigidity of the both side regions 8 is too high, the ground contact is not stable, and the steering stability during turning is deteriorated. Therefore, in the present invention, high-elasticity steel cords are arranged in the central region 7 and low-elasticity steel cords are arranged in both side regions, thereby improving high-speed straight running stability and steering stability during turning. ing.

  As a preferable means for making the steel cords embedded in the both side regions 8 have low elasticity, a plurality of steel wire bodies molded at substantially the same pitch on the steel cords in the both side regions 8 are substantially in phase. For example, a steel cord that is bundled without being twisted and spirally formed may be used. In this case, the steel cord embedded in the rubber in the central region 7 may be a twisted cord, and is preferably spirally formed at substantially the same pitch. Thus, the most efficient method is to dispose the spiral belt layer 6 with the tension (tensile force) in the central region 7 larger than that in the side regions 8.

  Further, as another preferred means for making the steel cord embedded in the side region 8 less 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 side region 8 is preferable. There can be mentioned means for making the steel cord larger than the amount of helical cording of the steel cord in the central region 7, and even if such means is adopted, the intended purpose can be achieved.

  In the present invention, the steel cords on both side regions 8 are bundled by twisting a plurality of steel wire bodies shaped at substantially the same pitch without being twisted at substantially the same phase, and spirally 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.

Specifically, the elastic modulus of the steel cord embedded in the rubber in the central region 7 is S (mm ² ) in terms of the strain-load characteristic when the rubber is adhered. When the load load W1 (N) at 0.5% elongation and the load load W2 (N) at 1.0% elongation is
(W2-W1) / S> 100
Satisfying the relationship represented by
When the steel cords embedded in the rubber in both side regions 8 are strain-load characteristics when the rubber is attached, when the cross-sectional area of the steel part of the steel cord is S (mm ² ), when the elongation is 0.5% The load load W1 (N) and the load load W2 (N) at 1.0% elongation are expressed by the following formula:
(W2-W1) / S <50
It is preferable to satisfy the relationship represented by these.

  When the strain-load characteristic of the steel cord wound around the central region 7 is (W2−W1) / S ≦ 100, the elastic modulus is about the same as that of the highly elastic organic fiber, and the circumferential rigidity is too low. Swelling cannot be sufficiently suppressed, and high-speed durability and high-speed straight running stability are reduced. On the other hand, when the strain-load characteristic of the steel cord wound around the both side regions 8 is (W2−W1) / S ≧ 50, the elastic modulus is the same as that of the highly elastic organic fiber, and the circumferential rigidity is too high. As a result, the ground contact is not stabilized, and a slip in the tire rotating direction is induced, and the steering stability during turning is lowered.

  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. For example, a method in which a steel cord is embedded in a rubber composite after the rubber is pressure-bonded to the cord from above and below is useful.

  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. If the central region 7 is less than 70% of the ground contact width, the elastic modulus of the spiral belt layer 6 existing in the ground contact surface at the time of straight traveling is lowered, and high speed durability and high speed straight running stability are lowered. If the contact width 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 high, so that the ground contact is not stable, and the steering stability is induced by inducing a slip in the tire rotating direction. It will decline.

  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 “JATMAYearBook” of the Japan Automobile Tire Association in Japan. ing.

  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.
(Conventional Examples 1 to 3 and Examples)
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. In these tires, the width of the central region was the same as the contact width. After that, we evaluated each of high-speed straight running stability, cornering steering stability and high-speed durability. In addition, the code sectional views of the spiral belt layers according to the conventional examples 1 to 3 and the examples are shown in FIGS.

<Evaluation method>
The rider evaluated the feeling of high-speed straight running and cornering steering stability. The results are shown as an index with Conventional Example 1 as 100. In any case, the larger the value, the better the stability and the better the result. For high-speed durability, a drum test was performed at a load of 1750 N, and the speed and running speed when a failure occurred by increasing the speed of 10 km / 10 min every 10 minutes from the initial speed of 180 km / h by the step speed method. Evaluation was performed in time. The results are shown as an index with Conventional Example 1 as 100. The larger the value, the better the high-speed durability and the better the result. These results are also shown in Table 1 below.

  From Table 1 above, it can be seen that the tire of the present invention is superior in steering stability during corner turning, high-speed straight running stability, and high-speed durability compared to conventional tires.

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 (3)

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 cords embedded in the both side regions are less elastic than the steel cords embedded in the rubber of the partial region,
The steel cords of the both side regions are bundled without twisting a plurality of steel wire bodies that are molded at substantially the same pitch at substantially the same phase, and are spirally molded,
The steel wire is a steel filament;
The steel cord embedded in the rubber in the central region has a 0.5% elongation when the cross-sectional area of the steel portion of the steel cord is S (mm ² ) in the strain-load characteristics with the rubber attached. Load load W1 (N) and load load W2 (N) at 1.0% elongation
(W2-W1) / S> 100
Satisfying the relationship represented by
The steel cords embedded in the rubber in the both side regions are stretched by 0.5% when the cross-sectional area of the steel part 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 1.0% elongation
(W2-W1) / S <50
A pneumatic tire for a motorcycle, characterized by satisfying the relationship expressed by:   The pneumatic tire for a motorcycle according to claim 1, wherein the steel cord in the central region is formed by twisting a plurality of steel wire bodies spirally formed at substantially the same pitch in substantially the same phase.   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 or 2, wherein a width of the central region is 70 to 130% of a contact width when the maximum width is set.

Images