JPH0717212A - Tire for motorcycle - Google Patents

Abstract

PURPOSE:To enhance the quality of ground contact by moderating the rigidity toward the radial direction inside of a tread portion and at the same time improve the quality of grip by forming a belt layer with more than one ply piece which is made up of a spiraled beltlike ply which is made up of belt cords covered with topping rubber. CONSTITUTION:A belt layer 7 arranged on the inside of a tread portion 2 is formed with more than one ply piece which is made up of a lengthy beltlike ply of narrow breadth whose more than one organic fiber cord or metal cord is covered with topping rubber and that is spiraled in almost parallel in regard to a tire equator. Also, each bead apex 15 interposed between the main body portion 6a of a carcass 6 and each winding-up portion 6b is formed into a section taper shape with a bead core 5 upper surface width as the lateral length of the base, and is provided with a height which is 0.3-0.5 times the height H of a tire section, and at the same time is formed of a rubber formation whose JISA hardness is not less than 50 deg. and not greater than 90 deg. and tandelta than 0.15. Also, in adjacency to this bead apex 15, a steel filler 18 is provided in the range of 0.3-0.5H.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire for a motorcycle, which can maintain a running stability in a straight running state at a high speed and can enhance a feeling of contact with a ground at the time of turning without lowering a feeling of rigidity.

[0002]

2. Description of the Related Art In a tire for a motorcycle, since the vehicle body travels with a large inclination when turning, a cross ply structure having a large lateral rigidity of the tire is required to maintain running stability even when turning. Tires have been widely used. However, in recent years, with the enhancement of the expressway network and with the improvement in the performance of vehicle bodies, even motorcycle tires are required to have improved performance for high-speed running, and radial tires are desired.

In this radial tire for a motorcycle, for example, a ply piece obtained by spirally winding a belt-shaped ply of a small width adjacent to the outside of a carcass, which is proposed by the present applicant in Japanese Patent Application No. 2-103305. Formed by. This one has a low bending rigidity inward in the radial direction, and therefore has a high ground contact property, so that running stability is improved.
Also, the envelope characteristics are good, and the riding comfort is improved.

Further, the cord of the ply is continuous in the circumferential direction and spirally wound substantially parallel to the equatorial plane, as compared with the conventional structure formed by joining cut plies, so that the belt layer has a high hoop effect. Moreover, it is possible to effectively prevent changes in the tire outer diameter due to centrifugal force, and it is possible to improve running performance during straight running, especially at high speeds.

However, the belt layer formed by spirally winding the belt-shaped ply has a low bending rigidity and flexibility with respect to the inner side in the radial direction of the belt layer at the time of turning when the vehicle body is inclined, and therefore is excellent in ground contact. The lateral spring constant from the tread part to the side wall part is relatively small, the lateral rigidity is poor, and it becomes difficult to induce the high side force required during turning, so the camber thrust is small and the turning performance is poor. There was a problem.

In order to supplement the lateral rigidity, Japanese Patent Application No. 2-1
In No. 17937, the original applicant proposed a method of increasing the tip height of the winding portion of the carcass, a method of increasing the tip height of the bead apex, and the like.

[0007]

However, although the lateral rigidity of the sidewall portion is increased by the above proposal, the response when the camber angle is given, that is, the time lag until the camber thrust is generated is relatively long, and therefore the driver expects. The camber thrust does not occur at the time of turning, and an excessive camber angle is given during cornering. As a result, an excessively large camber thrust is likely to occur after the time lag, resulting in excessive bending. At this time, the driver will be in an unstable driving situation in which he / she must hurry up and raise the vehicle body to correct it.

In addition to turning at high speeds, it is necessary to avoid bumps and obstacles on the road surface when driving straight ahead, and a camber accompanies the driving. In addition, when running at high speed, vibration of the vehicle body induced by the unevenness of the road surface, that is, a weave phenomenon tends to occur.

As a result of various investigations in order to solve the above-mentioned problems, the present inventor found that the lateral spring constant of a tire was the highest in the range of 30 to 40 degrees at which the maximum camber angle was obtained, and further the kimber angle was 0. It has been found that it is more preferable that the lateral spring constant gradually increases as the degree becomes larger.

Further, in order to satisfy the condition of the lateral spring constant, rather than the height regulation of the bead apex and the height regulation of the winding portion of the carcass, rather than the upper surface of the bead core between the carcass main body and its winding portion, the taper is performed. A bead apex made of a hard rubber composition having a cross-sectional shape and a filler made of a steel cord are integrally provided, and the hardness, viscoelastic characteristics, capacity of the rubber composition, the position of the filler, and the thickness and inclination of the cord. Experiments have confirmed that it is effective to regulate the corners.

According to the present invention, while maintaining traveling stability when traveling straight at high speed, when turning, the feeling of rigidity is increased as the camber angle increases, and the camber thrust relative to the camber angle is generated earlier to improve the steering stability. It is an object of the present invention to provide a motorcycle tire capable of enhancing the feeling of contact with the ground and improving the high-speed straightness and the turning performance.

[0012]

SUMMARY OF THE INVENTION The present invention has a main body portion extending from an arc-shaped tread portion through a sidewall portion to a bead portion, and a winding portion that is continuous with the main body portion and is folded back around a bead core of the bead portion. And a carcass consisting of one or more carcass plies in a radial arrangement and a belt layer arranged inside the tread portion and radially outside the carcass. In the above-mentioned motorcycle tire, the belt layer is formed by spirally winding a narrow and long strip-shaped ply in which one or more organic fiber cords or metal cords are covered with a topping rubber, substantially parallel to the equator of the tire. The bead core is formed of one or more ply pieces, and the width of the upper surface of the bead core is defined as the horizontal length of the bottom side between the carcass body and the winding portion. Ri in the shape of the cross section, a tire section height H
0.3-0.5 times as high and JIS A hardness of 50 °
A bead apex made of a rubber composition having a tan δ of 0.15 or more and a tan δ of 0.15 or more is arranged. Steel cords are arranged adjacent to the bead apex within a range of ± 15 ° with respect to the radial direction. A steel filler is formed in a range of a height 0.3 to 0.5 times a tire cross-section height H from the vicinity of the upper surface of the bead core.

[0013]

Since the belt layer is composed of ply pieces formed by spirally winding a band-shaped ply in which a belt cord is embedded in topping rubber, the radius of the tread portion is larger than that of a conventional one formed by using cut plies. It softens the rigidity toward the inside of the direction, improves ground contact and grip. In addition, there is no seam in the direction that inclines with respect to the tire equator like the conventional belt layer that joins cut plies,
The uniformity of the tire is improved, and the steering stability when going straight and turning can be improved.

Further, an apex having a triangular cross-section made of a rubber composition in which the JISA hardness and viscoelastic properties of the rubber are regulated is arranged between the main body of the carcass ply and the winding portion. Furthermore, by arranging the steel filler using a steel cord at a certain height along the bead apex, the lateral spring constant increases and the lateral rigidity improves, and the response when a camber angle is given, that is, the occurrence of camber thrust. Therefore, the steering stability is improved regardless of whether the vehicle is going straight or turning. At the same time, the feeling of contact with the ground and the feeling of contact with the ground can be increased, and the running stability when turning can be improved. Also, by increasing the viscoelastic characteristics of the bead apex, especially by increasing the value of tan δ to more than 0.15, the vibration damping performance is improved, and the low-frequency vibration that often occurs when the motorcycle is running is effectively prevented, and stability during maneuvering is improved. And improve the riding comfort.

The above-mentioned lateral spring constant means that while the tire is mounted on a rim and a specified inner pressure is applied to the tire inner cavity, the specified maximum load is applied to the tire to cause it to bend, and And the lateral force when the tire ground contact surface is slid laterally are measured, the correlation with the deflection is obtained, and the lateral deflection-load curve is expressed by the gradient of the tangential line in the lateral direction.

When the cord inclination angle of the filler is more than ± 15 ° with respect to the radial direction, the rate of increase of the lateral spring constant with respect to the camber angle is small, so that the camber thrust with respect to the camber angle is delayed and the turning performance is deteriorated.

If the apex has a rubber hardness of less than 50 degrees according to JIS A, the rigidity of the side wall is inferior. As a result, the feeling of rigidity during turning decreases, the running stability decreases during turning, and the durability deteriorates. On the other hand, if it exceeds 90 degrees, the workability of the rubber composition is deteriorated, and the rigidity of the tread shoulder region becomes excessive, so that the riding comfort and stability in straight traveling and turning traveling deteriorate.

Further, in the bead apex rubber and steel filler, the heights Ha and Hf in the radial direction from the bead base line BL at the upper end are 0.3 of the tire cross-section height Ha.
~ 0.5 times the height range. This is because if it is less than 0.3H, the capacity of the apex rubber is insufficient and the feeling of rigidity and ground contact are poor, while if it exceeds 0.5H, the rigidity in the tread shoulder region becomes excessive and the riding comfort deteriorates.

Further, the apex is disposed integrally with the steel filler, whereby the rigidity difference between the bead portion and the sidewall portion is mitigated and the rigidity is enhanced to further improve the running stability during turning. It is possible.

As described above, in the motorcycle tire according to the present invention, the above-mentioned components are organically combined and integrated to enhance the feeling of ground contact without deteriorating the feeling of rigidity and the running stability during straight running. Therefore, it is possible to improve traveling stability during turning while maintaining the above.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 3, in the tire 1 for a motorcycle, a tread width TW, which is a distance in the tire axial direction between the edges E of the tread portion 2, has a maximum tire width, and a tread surface 2A.
Has an arc shape centered on the tire equator C.

The tread portion 2 and the side wall portions 3 and 3 extending from both ends of the tread portion 2 toward the inner side in the tire radial direction,
The sidewall portion 3 has a pair of bead portions 4 and 4 located at the inner end in the tire radial direction. Further, the motorcycle tire 1 includes the tread portion 2 to the sidewall portion 3
A carcass 6 having a winding-up portion 6b that folds back a bead core 5 of the bead portion 4 from the inner side to the outer side in the tire axial direction in a main body portion 6a that passes through to the bead portion 4, and a tread portion 2
And a belt layer 7 arranged on the outer side in the radial direction of the carcass 6.

Further, between the body portion 6a of the carcass 6 and the folded-back portion 6b on the outer side of the bead core 5 in the tire radial direction,
A bead apex 15 having a tapered cross-sectional shape and having a width of the upper surface of the bead core 5 and a lateral length of the bottom, which is made of a rubber composition having a JIS A hardness of 50 ° to 90 °, and a steel filler 18 are set up together.

The bead apex 15 has a height of 0.3 to 0.5 times the sectional height H of the tire, and J
ISA hardness is 50 ° or more and 90 ° or less, and tan δ is 0.
15 or more rubber compositions are used.

If the JIS A hardness of the apex is less than 50 degrees, the lateral rigidity of the sidewall portion is poor, the rigidity during turning is reduced, the running stability during turning is reduced, and the durability is poor. When it exceeds 90 degrees, the workability of the rubber composition is deteriorated, and the rigidity of the tread shoulder region becomes excessive, resulting in a comfortable ride in straight running and turning,
Stability decreases.

Further, by increasing the value of loss tangent tan δ of the bead apex to more than 0.15, the vibration damping performance is improved, and the low frequency vibration that often occurs during the running of the two-wheeled vehicle is effectively prevented and the steering stability and the steering stability are improved. Bringing a comfortable ride. To prevent heat generation, set the loss tangent tan δ to 0.3.
Make it smaller than 5.

Such a bead apex 15 together with the steel filler 18 has an increased lateral spring constant and can improve lateral rigidity. Therefore, the response response when the camber angle is given, that is, the time until the camber thrust is generated is short, and the steering stability is improved regardless of whether the vehicle is going straight or turning. Further, the feeling of contact with the ground is improved and the running stability during turning can be improved.

The steel filler 18 is adjacent to the bead apex and has steel cords within the radial direction of ±.
It is arranged in the range of 15 ° and is 0.3 to 0.5 times the height H of the tire cross section from the vicinity of the upper surface of the bead core.

In the steel filler, the steel cord is formed by twisting filaments having a filament diameter of 0.15 to 0.25 mm in the same direction with an upper twist of 10 mm pitch or less and a lower twist of 6 mm pitch or less.

When the cord inclination angle of the filler is ± 15 ° or more with respect to the radial direction, the rate of increase in the lateral spring constant with respect to the camber angle becomes small, and the camber thrust is delayed and the turning performance deteriorates.

Further, in the bead apex rubber and steel filler, the heights Ha and Hf of the upper end of the bead apex rubber from the bead base line BL in the radial direction are 0.3 of the tire cross section height Ha.
~ 0.5 times the height range. This is because if it is less than 0.3H, the capacity of the apex rubber is insufficient and the feeling of rigidity and ground contact are poor, while if it exceeds 0.5H, the rigidity in the tread shoulder region becomes excessive and the riding comfort deteriorates.

Moreover, the apex and the steel filler are integrally disposed between the carcass main body portion 6a and the folded portion 6b, whereby the rigidity difference from the bead portion to the sidewall portion is alleviated. In addition, the rigidity can be increased and the running stability at the time of turning can be improved.

On the other hand, the carcass 6 in the present embodiment comprises one or more carcass cords having a radial arrangement of carcass inclined at an angle of 70 to 90 degrees with respect to the tire equator C, and one carcass in the present embodiment. The carcass cord is made of ply, and as the carcass cord, an organic fiber cord having a modulus of elasticity of 600 kgf / mm ² or more, such as nylon, polyester, or aromatic polyamide fiber, is used. In the present embodiment, the carcass 6 has a hoisting height Ht, which is the height of the hoisting portion 6b from the bead base line BL, set in the range of 0.2 to 0.6 times the tire cross-section height H. .

In this embodiment, the belt layer 7 has a length BS between outer edges of the belt layer in the tire meridian section which is 0.8 times or more the length L between the tread edges E along the tread surface 2A and 0. It is set within the range of 9 times or less.

The belt layer 7 is a narrow and long strip-shaped ply 1.
It consists of a ply piece 8 formed by spirally winding 0. As shown in FIG. 2, the belt-shaped ply 10 is formed by embedding one or a plurality of belt cords 11 and 11 arranged in parallel in the topping rubber 12 in the present embodiment. The belt cord 11 is made of nylon, In addition to organic fiber cords such as polyester and aromatic polyamide, steel cords are used. As the belt cord 11, the aromatic polyamide fiber having tensile strength and elastic modulus substantially equal to that of steel and having a weight smaller than that of steel can be preferably used.

The belt-shaped ply 10 extends from the starting point H1 which is the outer edge F of the belt layer 7 located in the vicinity of one end edge E of the tread portion 2 from left to right in FIG. 1 and at the tire equator C.
The ply piece 8 can be formed by spirally winding at a small angle of 5 ° or less with respect to the tire equator C until reaching the end point H2 forming the outer edge F of the belt layer 7 in the vicinity of the other end edge E. .

In this embodiment, when the strip-shaped ply 10 is wound, as shown in FIG. 3, the strip-shaped ply 10 is wound around the opposite side edges 10a and 10a so as to be wrapped with each other so as to be loosened. To prevent. The belt layer 7 may be formed of two or more ply pieces 8 having the above-described configuration, that is, a plurality of layers in which the spiral winding of the band-shaped ply 10 is two or more layers.

When the cords of the carcass 6 are arranged in a radial arrangement as in this embodiment, the belt layer 7 is
The belt cord cooperates with the cord of the carcass 6 to exert a hoop effect.

[0039]

SPECIFIC EXAMPLE 1 A preliminary experiment was conducted in order to confirm the effect of the steel filler 18 on improving the feeling of contact with the ground and the feeling of rigidity.

A tire size of 190 / 50R17 was prototyped according to the main specifications (specifications A, B and C) shown in Table 1, and the lateral spring constant was measured in the camber angle range of 0 to 40 °. Equip the actual vehicle with tires,
The effect of Fira was confirmed by running in an actual vehicle. In addition, the spring constant has two levels of load (100kg and 200kg),
Further, the feeling of contact with the ground and the feeling of rigidity were judged by the feeling of the driver. The test results are shown in Table 1.

[0041]

[Table 1]

As a result of the test, it was confirmed that the specification C including the steel filler had a good ground feeling and a good rigidity feeling.

[0043]

Concrete Example 2 Based on the result of the preliminary test according to Concrete Example 1, the tire size is 190 / 50R1 which is the same as that of Concrete Example 1.
A tire having No. 7 and having the configuration of FIG. 1 was prototyped according to the specifications shown in Table 2 (Examples 1 to 5) and its performance was tested. For comparison, a tire having a conventional structure in which a filler is not provided (Comparative Example 1) and tires having Comparative Examples 2 to 5 other than the structure of the present application were also tested and their performances were compared.

The test conditions are as follows. 1) Steering stability during straight running and during turning A trial tire was mounted on a motorcycle, and the automobile was run at 260 km / Hr on a test road, and evaluated according to the feeling of a test driver. It is displayed with the index. The larger the value, the better.

2) Camber Thrust Generation Speed 1) In the test, the driver's feeling was evaluated. The test results are shown in Table 2.

[0046]

[Table 2]

[0047]

INDUSTRIAL APPLICABILITY As described above, the motorcycle tire of the present invention can improve the steering stability during straight traveling and turning during high-speed traveling.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing an example of a strip ply.

FIG. 3 is a cross-sectional view illustrating the winding of the band-shaped ply.

[Explanation of symbols]

 2 tread part 3 sidewall part 4 bead part 5 bead core 6 carcass 6a body part 6b winding part 7 belt layer 10 belt-shaped ply 11 belt cord 12 topping rubber 18 steel filler BS belt length C tire equator F outer edge

Claims (2)

[Claims] 1. A body part extending from an arc-shaped tread part to a bead part through a sidewall part and a winding part which is continuous with the body part and which is folded around a bead core of the bead part and which has at least one radial arrangement. A motorcycle tire having a carcass made of a carcass ply and a belt layer arranged inside the tread portion and radially outside the carcass, with the distance between the tire axial ends of the tread portion being the maximum width of the tire. The belt layer is composed of one or more ply pieces obtained by spirally winding a narrow and long strip-shaped ply obtained by coating one or more organic fiber cords or metal cords with a topping rubber, substantially parallel to the tire equator. While being formed, between the main body of the carcass and the winding portion, in a tapered cross section with the width of the upper surface of the bead core as the lateral length of the bottom side,
0.3 to 0.5 times the height H of the tire section and JI
SA hardness of 50 ° or more and 90 ° or less, tan δ of 0.1
A bead apex made of a rubber composition of 5 or more is arranged, and a steel filler is arranged adjacent to the bead apex within a range of ± 15 ° with respect to the radial direction. A tire for a motorcycle, which is arranged in a height range of 0.3 to 0.5 times the height H. 2. The steel filler of the steel filler, wherein the steel cord is formed by twisting filaments having a filament diameter of 0.15 to 0.25 mm in the same direction with an upper twist of 10 mm pitch or less and a lower twist of 6 mm pitch or less. The tire for a motorcycle according to claim 1.