JP2021130380A - Bias tire for bicycle - Google Patents

Abstract

To provide a bias tire for a bicycle which can improve durability performance in high speed traveling.SOLUTION: A bias tire 1 for a bicycle includes a carcass 6 having a bias structure. The bias tire includes a tread rubber 7 forming a tread part 2, and a side wall rubber 8 arranged inside in a tire radial direction of the tread rubber 7. The tread rubber 7 is connected to the side wall rubber 8 through an interface 9. The side wall rubber 8 includes a side body part 8a forming a pair of side wall parts 3, and a connection part 8b for connecting the pair of side body parts 8a.SELECTED DRAWING: Figure 1

Description

The present invention relates to a bias tire for a two-wheeled vehicle including a carcass having a bias structure.

Conventionally, a bias tire for a two-wheeled vehicle including a carcass having a bias structure is known. For example, Patent Document 1 below proposes a bias tire for a motorcycle that achieves both weight reduction and steering stability by specifying the inclination angle of the carcass line.

Japanese Unexamined Patent Publication No. 2000-185511

However, in the two-wheeled vehicle bias tire of Patent Document 1, the tread rubber may be destroyed at an early stage due to heat generated by the deformation of the tread rubber during high-speed running, and there is room for further improvement in durability performance during high-speed running. ..

The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a bias tire for a two-wheeled vehicle capable of improving durability at high speeds.

The present invention is a bias tire for a two-wheeled vehicle including a carcass having a bias structure, and includes a tread rubber forming a tread portion and a sidewall rubber arranged inside the tread rubber in the tire radial direction. , The sidewall rubber is connected to the sidewall rubber via an interface, and the sidewall rubber includes a side main body portion forming a pair of sidewall portions and a connecting portion connecting the pair of the side main body portions. It is characterized by.

In the two-wheeled vehicle bias tire of the present invention, the outer end of the interface in the tire axial direction is located inside the tire radial direction and on the outer surface of the tire with respect to the tread end which is the end of the tread portion in the tire axial direction. Is desirable.

In the two-wheeled vehicle bias tire of the present invention, the distance in the tire radial direction between the outer end of the interface and the tread end is preferably 20 mm or less.

In the two-wheeled vehicle bias tire of the present invention, the height Ho in the tire radial direction from the bead baseline at the outer end of the interface is 60% of the tire radial height HS from the bead baseline at the tread end. It is desirable that it is the above.

In the two-wheeled vehicle bias tire of the present invention, the thickness of the connecting portion is preferably 2.0 mm or less.

In the two-wheeled vehicle bias tire of the present invention, the tread portion includes a plurality of grooves, the grooves are provided with a plurality of slip signs for indicating a wear state of the tread portion, and the connection portion is a tire equatorial line. It is desirable that the tire is located inside the tire radial direction with respect to the surface of the slip sign closest to the tire.

In the two-wheeled vehicle bias tire of the present invention, it is desirable that the end portion of the interface in the tire axial direction is convex and curved inward in the tire radial direction.

In the two-wheeled vehicle bias tire of the present invention, it is desirable that the loss tangent tanδS of the sidewall rubber at 70 ° C. is smaller than the loss tangent tanδT of the tread rubber at 70 ° C.

In the two-wheeled vehicle bias tire of the present invention, it is desirable that the ratio of natural rubber to 100 parts by mass of the rubber component of the sidewall rubber is 30 parts by mass or more.

In the two-wheeled vehicle bias tire of the present invention, the tread rubber is connected to the sidewall rubber via an interface, and the sidewall rubber includes a side main body portion forming a pair of sidewall portions and a pair of the side bodies. It includes a connection part that connects the main body part. In such a bias tire for a two-wheeled vehicle, the durability performance at high speed can be improved by the presence of the sidewall rubber between the tread rubber and the carcass.

It is a tire meridian cross-sectional view which shows one Embodiment of the bias tire for a motorcycle of this invention. It is a development view of a tread part.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view of a tire meridian in a normal state of the bias tire 1 for a motorcycle of the present embodiment (hereinafter, may be simply referred to as “tire 1”).

Here, the "normal state" is a state in which the tire 1 is rim-assembled on the normal rim, adjusted so as to have a normal internal pressure, and no load is applied. In the present specification, unless otherwise specified, the dimensions of each part of the tire 1 are values measured in a normal state.

Further, the "regular rim" is a rim defined for each tire in the standard system including the standard on which the tire 1 is based. For example, "standard rim" for JATTA and "Design" for TRA. Rim ", ETRTO is" Measuring Rim ".

In addition, the "regular internal pressure" is the air pressure defined for each tire in the standard system including the standard on which the tire 1 is based. For JATMA, the "maximum air pressure", and for TRA, the table "TIRE". The maximum value described in "LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO.

As shown in FIG. 1, the tire 1 of the present embodiment includes a tread portion 2, a pair of sidewall portions 3 extending inward in the tire radial direction from both ends of the tread portion 2, and an inner side in the tire radial direction of the sidewall portion 3. Includes a pair of bead portions 4 located at. For example, bead cores 5 are embedded in each of the pair of bead portions 4.

The tread surface 2s, which is the outer surface of the tread portion 2, extends from the tire equator C to the tread end Te, for example, in an arc shape that is convex outward in the radial direction of the tire. It is desirable that the tread width Wt, which is the linear width in the tire axial direction between the tread end Tes, is the maximum tire width.

Such a tire 1 can be turned with a large camber angle. Here, the tread end Te is the end of the tread portion 2 in the tire axial direction, and the tire equatorial line C is the center of the tread end Te in the tire axial direction.

The tire 1 of the present embodiment includes a carcass 6 having a bias structure that extends from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4. The carcass 6 includes a main body portion 6a straddling between the pair of bead cores 5 and a folded-back portion 6b connected to the main body portion 6a and folded around the bead core 5.

The carcass 6 having a bias structure includes at least one carcass ply 6A and 6B in the present embodiment. The carcass ply 6A and 6B each include a carcass cord that is tilted at an angle of 30 to 60 ° with respect to the tire equator C, for example. It is desirable that the carcass plies 6A and 6B are arranged in opposite directions so that the carcass cords intersect each other between the plies.

The tire 1 of the present embodiment includes a tread rubber 7 forming the tread portion 2 and a sidewall rubber 8 arranged inside the tread rubber 7 in the tire radial direction. The tread rubber 7 of the present embodiment is connected to the sidewall rubber 8 via the interface 9. That is, the tread rubber 7 and the sidewall rubber 8 of the present embodiment are made of different rubbers.

For such a tire 1, a rubber having excellent grip performance can be used as the tread rubber 7, and a rubber having excellent absorption performance can be used as the sidewall rubber 8. Therefore, the tire 1 of the present embodiment can improve the steering stability performance during turning.

The sidewall rubber 8 of the present embodiment includes a side main body portion 8a forming a pair of sidewall portions 3 and a connecting portion 8b connecting the pair of side main body portions 8a. In such a tire 1, heat generation due to distortion of the tread rubber 7 during high-speed running is suppressed by the presence of the sidewall rubber 8 between the tread rubber 7 and the carcass 6, and the durability performance during high-speed running is improved. Can be made to. Further, since the energy loss of the tread portion 2 of the tire 1 is reduced, the rolling resistance can be reduced and the fuel efficiency can be improved.

In a more preferred embodiment, the outer end 9a of the interface 9 in the tire axial direction is located inside the tire radial direction and on the outer surface of the tire with respect to the tread end Te which is the end of the tread portion 2 in the tire axial direction. In such a tire 1, even when turning with a large camber angle, the tread rubber 7 is always in contact with the ground, and there is no possibility that the sidewall rubber 8 is in contact with the ground. Therefore, in the tire 1 of the present embodiment, the grip performance does not suddenly change when the sidewall rubber 8 touches the ground during turning, and the steering stability performance can be improved.

The distance L1 in the tire radial direction between the outer end 9a of the interface 9 and the tread end Te is preferably 20 mm or less. When the distance L1 is 20 mm or less, the outer end 9a of the interface 9 can be positioned on the outer surface of the tire with less distortion during turning, and the durability performance of the tire 1 can be improved. From this point of view, the distance L1 is more preferably 15 mm or less.

The height Ho in the tire radial direction from the bead baseline BL at the outer end 9a of the interface 9 is preferably 60% or more, more preferably 60% or more of the height HS in the tire radial direction from the bead baseline BL at the tread end Te. Is 70% or more. In such a tire 1, the outer end 9a of the interface 9 can be positioned on the outer surface of the tire with less distortion during turning, and the durability performance can be improved. Here, the bead baseline BL corresponds to a line that defines the rim diameter of the regular rim on which the tire 1 is mounted.

The height Ho of the outer end 9a of the interface 9 is preferably 98% or less, more preferably 95% or less of the height HS of the tread end Te. Even when such a tire 1 is turned with a large camber angle, there is no possibility that the sidewall rubber 8 will come into contact with the ground, and the steering stability performance of the tire 1 during turning running can be improved.

The tire 1 may have a reinforcing layer 10 arranged on the outside of the carcass 6 in the radial direction of the tire and inside the tread portion 2, for example. The reinforcing layer 10 includes at least one reinforcing ply 10A, and in this embodiment, one reinforcing ply 10A. The connecting portion 8b in this case is located on the reinforcing layer 10. Such a tire 1 can suppress deformation during high-speed running and improve high-speed durability performance.

FIG. 2 is a developed view of the tread portion 2 of the present embodiment. FIG. 1 is a cross-sectional view taken along the line AA of FIG. As shown in FIGS. 1 and 2, the tread portion 2 of the present embodiment includes a plurality of grooves 11. The shape of the groove 11 is not limited to the one shown in the drawing, and may include, for example, a circumferential groove extending in the tire circumferential direction.

The groove 11 is provided with, for example, a plurality of slip signs 12 for indicating a wear state of the tread portion 2. Here, the slip sign 12 is a portion that protrudes outward in the radial direction of the tire from the groove bottom of the groove 11, and the tread portion 2 is worn and the slip sign 12 is exposed on the tread surface 2s, which serves as a guideline for tire replacement. Is what it becomes.

As shown in FIG. 1, the connecting portion 8b of the present embodiment is located inside the surface 12a of the slip sign 12 closest to the tire equator C in the tire radial direction. Such a connecting portion 8b is unlikely to be exposed to the tread surface 2s even if the vicinity of the tire equator C where the wear progresses most is worn up to the slip sign 12. Therefore, in the tire 1 of the present embodiment, even when the wear progresses, the connection portion 8b does not touch the ground and the grip performance does not change suddenly, and the steering stability performance can be improved.

The thickness t of the connecting portion 8b is preferably 0.5 mm or more, more preferably 0.8 mm or more. The thickness t of the connecting portion 8b is preferably 2.0 mm or less, more preferably 1.8 mm or less. Such a connecting portion 8b is suitable for suppressing heat generation due to distortion of the tread rubber 7 during high-speed traveling.

The end portion 9b of the interface 9 of the present embodiment in the tire axial direction is convex and curved inward in the tire radial direction. Since the ratio of the sidewall rubber 8 in the vicinity of the end portion 9b is small at such an interface 9, it is possible to improve the steering stability performance of the tire 1 when turning with a large camber angle.

The loss tangent tanδS of the sidewall rubber 8 of the present embodiment at 70 ° C. is smaller than the loss tangent tanδT of the tread rubber 7 at 70 ° C. Such a sidewall rubber 8 is excellent in absorption performance, and can improve the riding comfort performance of the tire 1. Here, the loss tangent tan δ at 70 ° C. is measured under the conditions of measurement temperature: 70 ° C., initial strain: 10%, amplitude: ± 1%, frequency: 10 Hz, deformation mode: tension, according to the provisions of JIS-K6394. It is a value measured using a "viscoelastic spectrometer".

In the sidewall rubber 8, the ratio of the natural rubber to 100 parts by mass of the rubber component is preferably 30 parts by mass or more, more preferably 40 parts by mass or more. Such a sidewall rubber 8 can suppress the occurrence of cracks and improve the durability performance of the tire 1.

Although the particularly preferable embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and can be modified into various embodiments.

A motorcycle bias tire having the basic structure shown in FIG. 1 was prototyped based on the specifications in Table 1 as an example. Further, as a comparative example, a bias tire for a two-wheeled vehicle in which a tread rubber and a sidewall rubber are integrally formed was prototyped. High-speed durability, steering stability, ride comfort and durability were tested using these prototype tires. The common specifications and test methods for each prototype tire are as follows.

<Common specifications>
Tire size: 130 / 70-13M / C
Rim size: 13 x 3.50 MT

<High-speed durability performance>
A prototype tire whose air pressure was adjusted to 250 kPa was mounted on a drum tester, and a load of 1.99 kN was applied to drive the tire at 81 km / h for 2 hours. After cooling to room temperature, the running speed was gradually increased every 30 minutes. The high-speed durability performance until it was raised and damaged was evaluated. The result is an index with a comparative example of 100, and the larger the value, the better the high-speed durability performance.

<Maneuvering stability performance>
A test rider lapped the test course using a medium-sized scooter equipped with prototype tires whose air pressure was adjusted to 225 kPa on the rear wheels. From the grip performance at this time, the feeling of ground contact, and the transient characteristics during turning, the steering stability performance of the prototype tire during turning was comprehensively evaluated by the sensuality of the test rider. The result is an index with a comparative example of 100, and the larger the value, the better the steering stability performance.

<Ride comfort performance>
Using a medium-sized scooter equipped with a prototype tire whose air pressure was adjusted to 225 kPa on the rear wheels, the ride quality performance when the test rider went around the test course was evaluated by the test rider's sensuality. The result is an index with a comparative example of 100, and the larger the value, the better the ride comfort performance.

<Durability>
A prototype tire, which was put into an ozone chamber having a concentration of 50 pphm for 3 weeks as an ozone deterioration treatment, was mounted on a drum tester after adjusting the air pressure to 225 kPa. Then, the durability performance was evaluated from the occurrence rate of cracks in the sidewall portion when a load of 3.29 kN was applied to the prototype tire and the tire was run for 10,000 km. The result is an index with a comparative example of 100, and the larger the value, the less cracks and the better the durability performance.

The results of the test are shown in Table 1.

As a result of the test, the two-wheeled vehicle bias tire of the example was excellent in high-speed durability performance as compared with the comparative example, and was also good in the overall performance evaluated by the total of each performance. Therefore, it was confirmed that the two-wheeled vehicle bias tire of the embodiment has improved durability at high speeds.

1 Bias tire for motorcycles 2 Tread part 3 Side wall part 6 Carcass 7 Tread rubber 8 Side wall rubber 8a Side body part 8b Connection part 9 Interface

Claims (9)

Bias tires for motorcycles, including carcass with a bias structure.
The tread rubber forming the tread portion and the sidewall rubber arranged inside the tread rubber in the radial direction of the tire are included.
The tread rubber is connected to the sidewall rubber via an interface.
The sidewall rubber includes a side body portion forming a pair of sidewall portions and a connecting portion connecting the pair of side body portions.
Bias tires for motorcycles. The two-wheeled vehicle bias according to claim 1, wherein the outer end of the interface in the tire axial direction is located inside the tread end in the tire radial direction and on the outer surface of the tire with respect to the tread end which is the end of the tread portion in the tire axial direction. tire. The two-wheeled vehicle bias tire according to claim 2, wherein the distance in the tire radial direction between the outer end of the interface and the tread end is 20 mm or less. The height Ho in the tire radial direction from the bead baseline at the outer end of the interface is 60% or more of the tire radial height HS from the bead baseline at the tread end, claim 2 or 3. Bias tires for motorcycles described in. The two-wheeled vehicle bias tire according to any one of claims 1 to 4, wherein the thickness of the connecting portion is 2.0 mm or less. The tread portion includes a plurality of grooves, and the tread portion includes a plurality of grooves.
The groove is provided with a plurality of slip signs for indicating the wear state of the tread portion.
The two-wheeled vehicle bias tire according to any one of claims 1 to 5, wherein the connecting portion is located inside in the radial direction of the tire with respect to the surface of the slip sign closest to the equator of the tire. The bias tire for a two-wheeled vehicle according to any one of claims 1 to 6, wherein the end portion of the interface in the tire axial direction is convex and curved inward in the radial direction of the tire. The motorcycle bias tire according to any one of claims 1 to 7, wherein the loss tangent tanδS of the sidewall rubber at 70 ° C. is smaller than the loss tangent tanδT of the tread rubber at 70 ° C. The motorcycle bias tire according to any one of claims 1 to 8, wherein the sidewall rubber has a ratio of natural rubber to 100 parts by mass of a rubber component of 30 parts by mass or more.

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