JP6946646B2 - Motorcycle tires - Google Patents

Description

The present invention relates to a motorcycle tire capable of exhibiting excellent turning performance.

For example, Patent Document 1 below proposes a tire for a motorcycle in which a belt layer is arranged inside the tread portion in order to increase the rigidity of the tread portion. The belt layer is composed of a belt ply in which a plurality of belt cords are inclined with respect to the equator of the tire.

In the belt ply of Patent Document 1, each belt cord is arranged at a constant inclination angle (45 °) in the crown region and the shoulder region of the tread portion. In such a tire, the rigidity distribution of the tread portion is not appropriate, and there is room for further improvement in turning performance.

Japanese Unexamined Patent Publication No. 2004-067058

The present invention has been devised in view of the above circumstances, and a main object of the present invention is to provide a tire for a motorcycle capable of exhibiting excellent turning performance.

The present invention is a tire for a motorcycle in which the tread portion is curved in an arc shape convex outward in the radial direction of the tire, and the tread portion is in a region of 1/3 of the tread deployment width centered on the tire equatorial line. It has a certain crown region and a pair of shoulder regions which are 1/6 of the tread deployment width on the tire equatorial side from the tread ends on both sides, and a plurality of belt cords are arranged inside the tread portion. A belt layer including at least one tread is arranged, and the belt ply is arranged in the crown region and each shoulder region, and the angle of the crown region with respect to the tire circumferential direction of the belt cord. θ1 is in the range of 60 to 90 °, and the angle θ2 of the belt cord in the shoulder region with respect to the tire circumferential direction is smaller than the angle θ1.

In the motorcycle tire of the present invention, it is desirable that the difference between the angle θ1 and the angle θ2 is 5 to 15 °.

In the motorcycle tire of the present invention, it is desirable that the length of the belt layer along the outer surface of the tread portion is 0.99 to 1.20 times the tread deployment width.

In the tire for a motorcycle of the present invention, the belt layer includes a first belt ply and a second belt ply arranged on the outer side of the first belt ply in the tire radial direction, and the belt of the first belt ply. It is desirable that the cord and the belt cord of the second belt ply are inclined in opposite directions in the shoulder region.

In the motorcycle tire of the present invention, a band layer is arranged inside the tread portion on the outside of the belt layer in the tire radial direction, and the band layer is the crown region and both outer regions thereof. The band ply has a band cord arranged at an angle of 5 ° or less with respect to the tire circumferential direction, and the crown is the number of cords driven per unit ply width. It is desirable that the end Ec of the band cord in the region is smaller than the end Eo of the band cord outside the crown region.

In the motorcycle tire of the present invention, it is desirable that the Ends Ec is 0.85 to 0.95 times that of the Ends Eo.

In the motorcycle tire of the present invention, it is desirable that the length of the band layer along the outer surface of the tread portion is 0.80 times or less the tread deployment width.

In the motorcycle tire of the present invention, it is desirable that a rubber layer having a thickness of 1.0 to 4.0 mm is provided between the belt ply and the band ply.

In the tire for a motorcycle of the present invention, it is desirable that the distance in the tire radial direction from the profile outer surface of the tread portion to the outer surface of the band ply is 3.0 to 6.0 mm at the tire equatorial line.

Inside the tread portion of the motorcycle tire of the present invention, a belt layer including at least one belt ply in which a plurality of belt cords are arranged is arranged.

In the belt ply of the motorcycle tire of the present invention, the angle θ1 of the belt cord in the crown region with respect to the tire circumferential direction is in the range of 60 to 90 °, and the angle θ2 of the belt cord in the shoulder region with respect to the tire circumferential direction is the angle. It is smaller than θ1.

Such a belt ply can increase the lateral force at the time of turning when the shoulder region touches the ground without excessively increasing the rigidity in the tire circumferential direction in the crown region, and thus excellent turning performance is exhibited. As described above, in the motorcycle tire of the present invention, the rigidity distribution in the crown region and the shoulder region can be made appropriate by the belt ply, and excellent turning performance can be exhibited.

It is sectional drawing which shows one Embodiment of the tire for a motorcycle of this invention. It is a development view of the tread reinforcement layer of FIG. It is an enlarged cross-sectional view of the tread part of FIG. It is explanatory drawing at the time of joining a belt ply base to a raw tire body. It is a developed view of the belt ply base of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of a tire including a tire rotation axis in a normal state of the motorcycle tire 1 of the present embodiment (hereinafter, may be simply referred to as a “tire”). The tire 1 of the present embodiment is suitably used for, for example, the front wheels of a motorcycle for road racing. However, the tire 1 of the present invention is not limited to such a usage mode.

The normal state is a state in which the tire is rim-assembled on a normal rim (not shown) and the tire is filled with normal internal pressure and has no load. Hereinafter, unless otherwise specified, the dimensions and the like of each part of the tire shall be the values measured in this normal state.

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

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

As shown in FIG. 1, in the tire 1 of the present embodiment, the tread portion 2 is curved outward in the radial direction of the tire in an arc shape. The tread portion 2 has a crown region 10, a pair of shoulder regions 11, and a pair of middle regions 12.

The crown region 10 is a region of 1/3 of the tread deployment width TWe centered on the tire equator C. The tread expansion width TWe is the distance along the outer surface of the tread portion 2 from one tread end Te to the other tread end Te.

The shoulder region 11 is a region of 1/6 of the tread deployment width on the tire equator C side from the tread end Te on both sides.

The middle region 12 is a region between the crown region 10 and each shoulder region 11. In FIG. 1, the middle region 12 and the crown region 10 are separated by a virtual boundary line 13. The middle region 12 and the shoulder region 11 are separated by a virtual boundary line 14.

The tire 1 of the present embodiment includes a carcass 6 and a tread reinforcing layer 15.

The carcass 6 reaches the bead core 5 of the bead portion 4 from the tread portion 2 through the sidewall portion 3. The carcass 6 is formed of, for example, two carcass plies 6A and 6B. Each carcass ply 6A, 6B includes, for example, a main body portion 6a and a folded portion 6b. The main body portion 6a reaches the bead core 5 from the tread portion 2 through the sidewall portion 3. The folded-back portion 6b is connected to the main body portion 6a and is folded around the bead core 5.

Each carcass ply 6A, 6B has, for example, a carcass cord arranged at an angle of 75 to 90 ° with respect to the tire circumferential direction. For the carcass cord, for example, an organic fiber cord such as nylon, polyester or rayon is preferably adopted.

A hard bead apex rubber 8 extending in a tapered shape from the bead core 5 is arranged between the main body portion 6a and the folded portion 6b. As a result, the bead portion 4 is reinforced.

The tread reinforcing layer 15 is provided outside the carcass 6 in the radial direction of the tire and inside the tread portion 2. The tread reinforcing layer 15 includes a belt layer 16 and a band layer 17.

The belt layer 16 includes at least one belt ply 20 in which a plurality of belt cords are arranged. The belt ply 20 is arranged in the crown region 10 and each shoulder region 11. For the belt cord, for example, an organic fiber cord such as nylon, rayon, or aromatic polyamide is adopted.

The belt layer 16 of the present embodiment includes a first belt ply 20A and a second belt ply 20B arranged on the outer side of the first belt ply 20A in the tire radial direction.

FIG. 2 shows a developed view of the tread reinforcing layer 15 of FIG. As shown in FIG. 2, the angle θ1 of the belt cord 19 of the crown region 10 with respect to the tire circumferential direction is in the range of 60 to 90 °. Such a belt ply 20 can provide an excellent feeling of rigidity when traveling straight and when turning at a small camber angle without excessively increasing the rigidity of the crown region 10 in the tire circumferential direction. If the angle θ1 is smaller than 60 °, the rigidity may become too high. In order to further enhance the above-mentioned effect, it is desirable that the angle θ1 is in the range of, for example, 65 to 85 °.

The angle θ2 of the belt cord 19 of the shoulder region 11 with respect to the tire circumferential direction is smaller than the angle θ1. Such a belt ply 20 can increase the lateral force when the shoulder region 11 is in contact with the ground and has a slip angle, and thus excellent turning performance is exhibited.

The difference between the angle θ1 and the angle θ2 is preferably 5 ° or more, more preferably 5 ° or more, in order to reduce the difference in rigidity when the crown region 10 or the shoulder region 11 touches the ground while exhibiting the above-mentioned effects. Is 7 ° or more, preferably 15 ° or less, and more preferably 12 ° or less.

As a more desirable embodiment, each belt cord 19 of the present embodiment has an angle with respect to the tire circumferential direction gradually decreasing from the tire equator C side toward the outside in the tire axial direction. In such an aspect, the change in the feeling of rigidity when the vehicle body is tilted down can be made linear.

In the present embodiment, the belt cord 19a of the first belt ply 20A and the belt cord 19b of the second belt ply 20B are inclined in opposite directions at least in the shoulder region 11. In the present embodiment, the belt cord 19a of the first belt ply 20A and the belt cord 19b of the second belt ply 20B are inclined in opposite directions in the entire region including the crown region 10. With such an arrangement of the belt cord 19, the rigidity of the shoulder region 11 can be effectively increased by the tag effect, and the stability at the time of high-speed turning can be enhanced.

The length L1 along the outer surface of the tread portion 2 of the belt layer 16 is, for example, 0.99 to 1.20 times the tread development width TWe (shown in FIG. 1 and the same applies hereinafter). desirable. Such a belt layer 16 can be expected to have the above-mentioned effect even when turning near the maximum camber angle.

The band layer 17 is provided, for example, on the outer side of the belt layer 16 in the tire radial direction. The band layer 17 includes a band ply 23 arranged in the crown region 10 and the middle regions 12 on both outer sides thereof. The band ply 23 has a band cord 22 arranged at an angle of 5 ° or less with respect to the tire circumferential direction. The band layer 17 can effectively suppress the growth of the outer diameter of the tread portion 2 when traveling at high speed. Further, the band layer 17 can increase the rigidity of the tread portion in the tire circumferential direction, and thus can improve the braking performance. For the band cord 22, for example, an organic fiber cord such as nylon, rayon, or aromatic polyamide is adopted.

The length L2 along the outer surface of the tread portion 2 of the band layer 17 is preferably 0.30 times or more, more preferably 0.45 times or more, preferably 0.80 times or less, more than the tread development width TWe. It is preferably 0.65 times or less. Such a band layer 17 can prevent the rigidity of the tread portion in the tire circumferential direction from being excessively increased while maintaining the braking performance.

It is desirable that the end Ec of the band code 22 in the crown region 10 is smaller than, for example, the end Eo of the band code 22 outside the crown region 10. Ends is the number of code inputs per unit ply width. Since such a band ply 23 exhibits excellent braking performance and the rigidity of the crown region 10 in the tire circumferential direction is moderately relaxed, for example, it is possible to lighten the tilting of the vehicle body from an upright state. can.

It is desirable that the number of Enz Ec and Eo is, for example, 20 to 40 per 5 cm of ply width. The ratio Ec / Eo of the Ends Ec to the Ends Eo is preferably 0.95 or less, more preferably 0.92 or less, and preferably 0 in order to obtain an appropriate rigidity while maintaining the braking performance. It is .85 or more, more preferably 0.88 or more.

FIG. 3 shows an enlarged cross-sectional view of the tread portion 2 of FIG. As shown in FIG. 3, it is desirable that a rubber layer 25 having a thickness of 1.0 to 4.0 mm and a thickness of t1 is provided between the belt ply 20 and the band ply 23. As a result, the thickness of the tread rubber 2G from the profile outer surface of the tread portion 2 to the outer surface of the band ply 23 can be appropriately reduced. Therefore, the rigidity of the tread portion 2 is appropriately increased, and the cornering power when traveling straight and at a relatively small camber angle is increased. The profile outer surface of the tread portion 2 means the outer surface in a state where the groove is filled when the tread portion 2 is provided with a groove. The outer surface of the band ply 23 means the outer surface of the band cord excluding the topping rubber.

In order to further enhance the above-mentioned effect while ensuring the thickness of the tread rubber 2G, the distance t2 in the tire radial direction from the profile outer surface of the tread portion 2 to the outer surface of the band ply 23 is preferably 3 in the tire equator C. It is preferably 0.0 mm or more, more preferably 4.0 mm or more, preferably 6.0 mm or less, and more preferably 5.0 mm or less.

Next, a method of forming the belt ply of the present embodiment will be described. FIG. 4 shows an explanatory view when the belt ply base 30 is joined onto the raw tire main body 29 whose outer diameter is bulged by the profile deck 28. FIG. 5 shows a developed view of the belt ply base 30 at this time. As shown in FIG. 4, the profile deck 28 has an arcuate cross section and has a ring shape extending in the tire circumferential direction, and its outer diameter can be expanded. A raw tire body 29 is arranged on the outer surface of the profile deck 28. The raw tire body 29 is curved in an arc shape that is convex outward in the radial direction of the tire by the profile deck 28. The raw tire body 29 rotates together with the profile deck 28.

A belt ply base 30 is arranged on the outer surface of the raw tire body 29. The belt ply base 30 is pressed against the outer surface of the raw tire body 29 by the stitch roller 31 while the raw tire body 29 is rotating.

As shown in FIG. 5, in the belt ply substrate 30, for example, the first region 36 on one side (right side in FIG. 5) of the tire equator C and the second region 37 on the other side (left side in FIG. 5) are separate. It is joined to the raw tire body 29 in the process of.

In the first step in which the first region 36 of the belt ply base 30 is joined, the raw tire body 29 rotates in the a direction, for example. The stitch roller 31 moves from the tire equator C toward the shoulder region 11a on one side (right side in FIG. 5) while pressing the belt ply base 30 against the raw tire body 29. As a result, the first region 36 of the belt ply base 30 is joined to the raw tire body 29.

The stitch roller 31 presses the belt ply base 30 against the raw tire body 29 in the shoulder region 11a on one side with a force larger than the force in the crown region 10. As a result, a force in the direction opposite to the a direction acts on the belt cord 19 in the shoulder region 11a. Therefore, the angle θ2 with respect to the tire circumferential direction in the shoulder region 11a of the belt cord 19 is smaller than the angle θ1 with respect to the tire circumferential direction in the crown region 10.

In the second step in which the second region 37 of the belt ply substrate 30 is joined, the raw tire body 29 rotates in the b direction opposite to that in the first step, for example. The stitch roller 31 moves from the tire equator C toward the shoulder region 11b on the other side (left side in FIG. 5) while pressing the belt ply base 30 against the raw tire body 29. As a result, the second region 37 is joined to the raw tire body 29.

For example, the stitch roller 31 presses the belt ply base 30 against the raw tire body 29 with a force larger than the force in the crown region 10 even in the shoulder region 11b on the other side. As a result, a force in the direction opposite to the b direction acts on the belt cord 19 in the shoulder region 11b. Therefore, the angle θ2 with respect to the tire circumferential direction in the shoulder region 11b of the belt cord 19 is smaller than the angle θ1 with respect to the tire circumferential direction in the crown region 10. As a result, the belt ply 20 described above can be obtained.

Although the motorcycle tire of one embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment described above, and may be modified to various embodiments.

Front tires for motorcycles having the basic structure of FIG. 1 and based on the specifications of Table 1 were manufactured and their performance was tested. As a comparative example, a front wheel tire for a motorcycle was prototyped in which each belt cord was inclined at 45 ° with respect to the tire circumferential direction in the entire area of the tread portion. The common specifications of each test tire are as follows.
Tire size: 120 / 70ZR17
Rim size: MT3.50 × 17
Internal pressure: 250 kPa
Carcass code: Rayon Belt code and band code: Aromatic polyamide Test vehicle: Motorcycle with a displacement of 1000cc

The turning performance, braking performance, and rigidity of each test tire were tested. The test method is as follows.

<Turning performance>
The turning performance when running on a circuit with the above test vehicle equipped with test tires was evaluated by the sensuality of the test rider. The "turning performance" is a comprehensive evaluation of the grip force during turning, the transient characteristics of the response when tilted, the steering angle, the roll characteristics, and the like. The result is a score with a comparative example of 100, and the larger the value, the better.

<Brake performance>
The braking performance when driving on a circuit with the above test vehicle equipped with test tires was evaluated by the sensuality of the test rider. "Brake performance" is a comprehensive evaluation of the maximum grip force during braking, the ease of grasping the limit of the grip force, the controllability of the braking force, and the like. The result is a score with a comparative example of 100, and the larger the value, the better.

<Rigidity>
The feeling of rigidity of the tread part when running on the circuit with the above test vehicle equipped with the test tire was evaluated by the sensuality of the test rider. The result is based on 100, and if it is less than 90, it indicates that the rigidity is insufficient, and if it is larger than 110, it indicates that the rigidity is excessive.
The test results are shown in Table 1.

As a result of the test, it was confirmed that the motorcycle tires of the examples exhibited excellent turning performance. It was also confirmed that the motorcycle tires of the examples had improved braking performance and a feeling of rigidity.

2 Tread part 10 Crown area 11 Shoulder area 19 Belt cord 16 Belt layer 20 Belt ply TWe tread deployment width θ1 Crown area belt cord angle θ2 Shoulder area belt cord angle

Claims (8)

A motorcycle tire in which the tread portion is curved in an arc shape that is convex outward in the radial direction of the tire.
Includes a carcass composed of two carcass plies from the tread portion through the sidewall portion to the bead core of the bead portion.
The tread portion is a pair of a crown region which is a region of 1/3 of the tread expansion width centered on the tire equator and a pair of regions which are 1/6 of the tread expansion width on the tire equator side from the tread ends on both sides. Has a shoulder area and
Inside the tread portion, a belt layer including a first belt ply and a second belt ply in which a plurality of belt cords are arranged, and a band layer provided on the outer side of the belt layer in the tire radial direction are arranged. And
The second belt ply is arranged on the outer side in the tire radial direction of the first belt ply.
Each of the first belt ply and the second belt ply is arranged in the crown region and each shoulder region.
For each of the first belt ply and the second belt ply
The angle θ1 of the belt cord in the crown region with respect to the tire circumferential direction is in the range of 60 to 90 °.
The angle θ2 of the belt cord in the shoulder region with respect to the tire circumferential direction is smaller than the angle θ1.
Ri difference 5 to 15 ° der of the angle θ2 and the angle .theta.1,
The band layer includes a band ply arranged in the crown region and both outer regions thereof.
The band ply has a band cord arranged at an angle of 5 ° or less with respect to the tire circumferential direction.
A tire for a motorcycle, characterized in that a rubber layer is provided between the second belt ply and the band ply. The motorcycle tire according to claim 1, wherein the length of the belt layer along the outer surface of the tread portion is 0.99 to 1.20 times the tread deployment width. It said belt cords before Symbol first belt ply, the The said belt cord of the second belt ply, said at shoulder region, motorcycle tire according to claim 1 or 2 are inclined in opposite directions. Relates Ends a code number of implanted per unit position ply width, Enz Ec of the band cord of the crown region, one of the smaller claim than Enz Eo of the band cord 1 to 3 on the outside of the crown area Tires for motorcycles described in. The motorcycle tire according to claim 4, wherein the Ends Ec is 0.85 to 0.95 times the Ends Eo. The motorcycle tire according to any one of claims 1 to 5 , wherein the length of the band layer along the outer surface of the tread portion is 0.80 times or less the tread deployment width. The motorcycle tire according to any one of claims 1 to 6, wherein the thickness of the rubber layer is 1.0 to 4.0 mm. The tire for a motorcycle according to any one of claims 1 to 7 , wherein the distance in the radial direction of the tire from the profile outer surface of the tread portion to the outer surface of the band ply on the tire equatorial line is 3.0 to 6.0 mm.

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