JP2009119968A - Pneumatic tire for motorcycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve grip in a large camber zone without lowering other performance in a pneumatic tire for a motorcycle. <P>SOLUTION: When a tread surface distance from a tire equatorial plane of a tread part 24 to a tread end 24E is L, and a length from a tire equatorial plane of a spiral belt layer 20 arranged on an outer circumference side of a mixture belt layer 18 to a belt end is B3, high stability during high speed linear traveling is obtained by satisfying 0.5L≤B3≤0.8L. Since there is no spiral belt layer 20 with strong binding force in a tread end side, a ground contacting area is secured in the large camber zone, and high grip is obtained. In an area of a tread end side, binding force necessary to suppress standing waves can be obtained while securing the ground contacting area by reducing an angle of a cord 19 of the mixture belt layer 18 with respect to a circumferential direction. In an area of a tire equatorial plane side, heat generation during linear traveling is suppressed without the binding force becoming too excessive by increasing the angle of the cord 19. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire for a motorcycle, and more particularly to a pneumatic tire for a motorcycle suitable for high-speed traveling.

  In recent race motorcycles, the cornering speed tends to increase year by year in order to reduce the lap time. For this reason, the camber is also deeper (larger), and the demand for grip in that region (large camber angle region) is high.

In recent years, the spiral belt layer, which has become the mainstream of tires for motorcycles, is effective for improving the stability during high-speed straightness, and the result is also recognized for racing motorcycles.
Examples of pneumatic tires for motorcycles using a spiral belt are disclosed in Patent Documents 1 and 2.
JP 05-504314 A JP 09-118109 A

However, when the spiral belt is used, since the restraint in the tire circumferential direction is too strong, the ground contact area (ground contact length) in the large camber region becomes small, and it is difficult to improve the grip during cornering. It was.
Therefore, if the spiral belt is arranged only on the center side of the tread and is not arranged on the tread end side, it is considered that the ground contact area can be increased in the large camber region on the tread end side where the spiral belt is not restrained. The tread portion has insufficient out-of-plane bending rigidity on the tread end side, and there is a concern that when a high load is applied due to this, a standing wave is generated to cause a tire failure.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a pneumatic tire for a motorcycle that can improve a grip in a large camber region without lowering other performance.

  The pneumatic tire for a motorcycle according to claim 1 is disposed on the outer side in the tire radial direction of the carcass including at least one ply straddling a pair of left and right bead cores in a toroidal shape, and with respect to the tire circumferential direction. A cross belt layer comprising two or more belt plies including a plurality of sloping cords, wherein the cords of the belt plies adjacent to each other are slanted in opposite directions with respect to a tire circumferential direction, and a tire of the cross belt layer A spiral belt layer including a cord that is disposed radially outside and spirally wound, and a tread rubber layer that is disposed outside the spiral belt layer in the tire radial direction and that constitutes a tread portion. The belt ply cord angle with respect to the belt end side is set smaller than the tire equatorial plane side, and the width of the cross belt layer is When the tread surface distance from the tire equatorial plane of the tread portion to the tread end is L, and the length from the tire equatorial plane to the ply end of the spiral belt layer is B, It is characterized by satisfying 0.5L ≦ B ≦ 0.8L.

Next, the operation of the pneumatic tire for a motorcycle according to claim 1 will be described.
In the pneumatic tire for a motorcycle according to claim 1, the spiral belt layer having a strong circumferential restraining force (tag effect) is disposed so as to satisfy 0.5 L ≦ B ≦ 0.8 L, so that the vehicle goes straight at high speed. High stability of time is ensured.

On the other hand, at the time of high-speed cornering (large camber region), the tread portion contacts the vicinity of the tread end (the tread end side from the position of 0.8 L from the tire equator plane).
On the tread end side from the position of 0.8 L from the tire equator plane, since the spiral belt layer with strong binding force is not disposed, the ground contact area (ground contact length) is larger than the portion where the spiral belt layer is disposed. It can be taken large, and a high grip can be obtained during high-speed cornering. Further, since the ground contact area (ground contact length) can be increased during high-speed cornering, the ground contact pressure per unit area is reduced and wear resistance is improved.

  Further, in the tread portion, a spiral belt layer having a strong binding force is not disposed in the region on the tread end side from the position of 0.8 L from the tire equatorial plane. Is relatively small on the tire equatorial plane side, so that the restraining force (tag effect) necessary to suppress the standing wave can be obtained while ensuring the above-mentioned ground contact area.

Further, in this pneumatic tire for a motorcycle, the angle of the cord of the cross belt layer with respect to the tire circumferential direction is larger on the tire equatorial plane side than the tread end side, so that the binding force (tag effect) of the cross belt layer is tread. The tire equatorial plane side can be made weaker than the end side, the restraint force by the spiral belt layer and the crossing belt layer on the tire equatorial plane side of the tread portion can be suppressed from becoming too strong, and heat generation during high-speed straight traveling can be suppressed. For this reason, high-speed durability can be obtained.
Thus, the pneumatic tire for a motorcycle according to claim 1 can improve the grip at the time of high-speed cornering (at the time of a large camber angle) without deteriorating other performances such as standing wave and high-speed durability.

Here, when 0.5L> B, the spiral belt layer does not exist on the ground contact surface at the time of large camber, and the stability at cornering deteriorates.
On the other hand, when B> 0.8L, the spiral belt layer occupies most of the ground contact surface at the time of large camber, and a sufficient improvement in grip at the time of large camber cannot be obtained.
The “length” of the ply is a dimension measured along a curve if the ply is curved.

  The invention according to claim 2 is the pneumatic tire for a motorcycle according to claim 1, wherein the cord of the crossing belt layer has an angle with respect to the tire circumferential direction within a range of 45 to 100 ° in the tire equatorial plane. It is characterized by that.

Next, the operation of the pneumatic tire for a motorcycle according to claim 2 will be described.
If the angle of the cord of the cross belt layer with respect to the tire circumferential direction is less than 45 ° on the tire equatorial plane, the restraining force (tag effect) of the cross belt layer becomes too strong near the tire equatorial plane, and heat is generated when driving straight ahead at high speed. It is disadvantageous to this.
On the other hand, if the angle of the cord of the crossing belt layer with respect to the tire circumferential direction exceeds 100 ° on the tire equator surface, the direction of inclination of the cord is reversed at the portion exceeding 90 °, and when manufacturing the belt ply However, it is difficult to bend the cord and to manufacture the cross belt layer.

  According to a third aspect of the present invention, in the pneumatic tire for a motorcycle according to the first or second aspect, the cord of the crossing belt layer has an angle with respect to a tire circumferential direction such that the end of the spiral belt layer and the tread end It is characterized by being in the range of 20 to 80 ° at an intermediate position.

Next, the operation of the pneumatic tire for a motorcycle according to claim 3 will be described.
When the angle of the cord of the cross belt layer with respect to the tire circumferential direction is less than 20 ° at an intermediate position between the end portion of the spiral belt layer and the tread end, the binding force (tag effect) of the cross belt layer is strong on the tread end side. As a result, the ground contact area necessary for securing a grip in the large camber region cannot be secured.
On the other hand, if the cord angle of the crossing belt layer with respect to the tire circumferential direction exceeds 80 ° at an intermediate position between the end portion of the spiral belt layer and the tread end, the binding force (tag effect) of the crossing belt layer becomes too small. The standing wave cannot be suppressed.

  As described above, since the pneumatic tire for a motorcycle of the present invention has the above-described configuration, it has an excellent effect that it is possible to achieve both improvement in grip in the large camber region and suppression of occurrence of standing waves.

Hereinafter, an embodiment of a pneumatic tire for a motorcycle according to the present invention will be described with reference to FIGS. 1 to 3.
As shown in FIG. 1, a pneumatic tire 10 for a motorcycle according to the present embodiment is arranged on at least one layer of a carcass 16 straddling a bead core 14 of a pair of left and right bead portions 12 and on the outer side in the tire radial direction of the carcass 16. The crossing belt layer 18, the spiral belt layer 20 disposed outside the crossing belt layer 18 in the tire radial direction, and the auxiliary belt layer 22 disposed outside the spiral belt layer 20 in the tire radial direction are provided.
A tread rubber layer 26 that forms the tread portion 24 is disposed outside the auxiliary belt layer 22 in the tire radial direction, and a side rubber layer 30 is disposed outside the carcass 16 in the tire width direction.

The cross belt layer 18 of the present embodiment includes two belts, a first belt ply 18A disposed on the inner side in the tire radial direction and a second belt ply 18B disposed on the outer side in the tire radial direction of the first belt ply 18A. Consists of belt ply.
As shown in FIGS. 2A and 2B, the first belt ply 18A and the second belt ply 18B are obtained by coating a plurality of cords 19 arranged in parallel with each other with a coating rubber. The cord 19 of the belt ply 18A and the cord 19 of the second belt ply 18B are inclined in directions opposite to each other with respect to the tire equatorial plane CL. For example, an aromatic polyamide cord or the like can be used as the belt ply cord 19.

As shown in FIG. 2 (A), the cord 19 of the first belt ply 18A of the present embodiment is inclined to the left as a whole when viewed from the tire outer peripheral side, and the angle with respect to the tire circumferential direction is the tire equatorial plane. It is formed in a curved shape so as to be smaller on the belt end side than CL. The angle of the cord 19 of the first belt ply 18A with respect to the tire circumferential direction is preferably within a range of 40 to 100 ° (αc) at the tire equatorial plane CL, and at an intermediate position between the end portion of the spiral belt layer 20 and the tread end 24E. A range of 20 to 80 ° (αs) is preferable.
As shown in FIG. 2 (B), the cord 19 of the second belt ply 18A is disposed so as to be inclined in the opposite direction to the cord 19 of the first belt ply 18A, and as a whole, it is inclined upward. ing. The regulation of the inclination angle of the cord 19 of the first belt ply 18A is the same as that of the cord 19 of the first belt ply 18A.
FIG. 3 schematically shows a state in which a cord 19 of the first belt ply 18A, a cord 19 of the second belt ply 18A, and a cord 21 of a spiral belt layer 20 described later are overlapped.
As shown in FIG. 1, the tread surface distance from the tire equatorial plane CL of the tread portion 24 to the tread end 24E is L, the length from the tire equatorial plane CL of the first belt ply 18A to the ply end is B1, and the second belt. It is preferable that 0.7L ≦ B1 ≦ 1.2L and 0.7L ≦ B2 ≦ 1.2L are satisfied when the length from the tire equatorial plane CL of the ply 18B to the end of the ply is B2.

As shown in FIGS. 1 and 3, the spiral belt layer 20 includes a rubber-coated cord in which one cord 21 is embedded in a coated rubber (or a belt-shaped rubber in which a plurality of cords are embedded in the coated rubber. (Coating cord layer) is spirally wound. In addition, as the cord 21 of the spiral belt layer 20, for example, an aromatic polyamide cord or the like can be used.
As shown in FIG. 1, when the tread surface distance from the tire equatorial plane CL of the tread portion 24 to the tread end 24E is L, and the length from the tire equatorial plane CL of the spiral belt layer 20 to the belt end is B3, It is preferable that 0.5L ≦ B3 ≦ 0.8L is satisfied.

  The auxiliary belt layer 22 is formed by coating a plurality of cords with an angle of 90 ± 5 ° with respect to the tire circumferential direction with a coating rubber. The auxiliary belt layer 22 is formed to have a width that completely covers the spiral belt layer 20. In addition, it is preferable that 0.7L ≦ B4 ≦ 1.2L is satisfied when the length from the tire equatorial plane CL to the belt end of the auxiliary belt layer 22 is B4.

  The tread rubber layer 26 of the present embodiment has a cap / base structure including a cap rubber layer 26C in contact with a road surface and a base rubber layer 26B disposed on the inner side in the tire radial direction of the cap rubber layer 26C. The base rubber layer 26B of the present embodiment is disposed only on the tire equatorial plane CL side and is not disposed on the tread end side, but may extend to the tread end side. Further, the base rubber layer 26B may be partially changed in thickness, for example, thick on the tire equatorial plane side and thin on the tread end side.

  Here, the cap rubber layer 26C is made of rubber having higher wear resistance than the base rubber layer 26B, and the base rubber layer 26B is made of rubber having lower heat generation than the cap rubber layer 26C. More specifically, rubber having a loss tangent tan δ smaller than that of the cap rubber layer 26C is used for the base rubber layer 26B.

(Function)
Next, the effect | action of the pneumatic tire 10 for two-wheeled vehicles of this embodiment is demonstrated.
In the pneumatic tire 10 for a motorcycle according to the present embodiment, the spiral belt layer 20 having a strong binding force in the circumferential direction is disposed on the outer peripheral side of the intersecting belt layer 18 of the carcass 16 so as to satisfy 0.5L ≦ B3 ≦ 0.8L. Therefore, high stability can be obtained when driving straight ahead at high speed.

  At the time of high speed cornering (large camber region), the tread portion 24 is in the vicinity of the tread end, but the spiral belt layer 20 is not disposed on the tread end side from the position 0.8 L from the tire equator plane CL. Since only the crossing belt layer 18 is disposed, the ground contact area (ground contact length) is increased as compared with the tread center region on the tire equatorial plane side where both the spiral belt layer 20 and the crossing belt layer 18 are disposed. And high grip is obtained during high-speed cornering. Furthermore, since the ground contact area in the vicinity of the tread end of the tread portion 24 that is grounded at the time of high-speed cornering is increased, the ground pressure per unit area is reduced and the wear resistance is also improved.

  In the tread portion 24, the spiral belt layer 20 having a strong binding force is not disposed in the region on the tread end side from the position of 0.8 L from the tire equatorial plane CL. Since the angle of the cord 19 with respect to the circumferential direction is relatively small on the tire equatorial plane side, a restraining force (tag effect) necessary for suppressing the standing wave can be obtained while ensuring the above-described ground contact area.

  Note that, in the tire center region of the tread portion 24 that comes in contact with a straight line, the cross belt layer 18 and the spiral belt layer 20 overlap each other, which is disadvantageous for heat generation as compared with the region of the cross belt layer 18 alone. The angle of the cord 19 of the intersecting belt layer 18 with respect to the tire circumferential direction is made larger than that of the tread end side so that the direction of the cord 19 is close to the tire width direction. ) Is not so large, and the binding force combined with the spiral belt layer 20 does not become too high. For this reason, heat generation in the tire center region during high-speed straight traveling can be suppressed.

As described above, in the pneumatic tire 10 for a motorcycle according to the present embodiment, by reviewing the belt structure, the grip at the time of high-speed cornering (at the time of a large camber angle) is obtained without deteriorating other performances such as standing wave and high-speed durability. It is suitable for use in road racing vehicles.
In the pneumatic tire 10 for a motorcycle according to the present embodiment, since the base rubber layer 26B having a low heat generation property is disposed in the tire center region of the tread portion 24, the structure is further advantageous for heat generation.

  Further, in the pneumatic tire 10 for a motorcycle according to this embodiment, the spiral belt layer 20 is completely covered with the auxiliary belt layer 22 including the cord whose angle with respect to the tire circumferential direction is 90 ± 5 °. A separation failure from the end of the belt layer 20 can be suppressed. The cord of the auxiliary belt layer 22 has an angle with respect to the tire circumferential direction of 90 ± 5 °, that is, extends in the tire width direction, and therefore has little influence on the rigidity in the circumferential direction. There is no suppression of movement.

Here, when 0.5L> B3, the spiral belt layer 20 does not exist on the ground contact surface during a large camber, and the stability during cornering deteriorates.
On the other hand, when B> 30.8 L, the spiral belt layer 20 occupies most of the ground contact surface at the time of large camber, and a sufficient improvement in grip at the time of large camber cannot be obtained.

Next, on the tire equator plane CL, when the angle of the cord 19 with respect to the tire circumferential direction is less than 45 °, the restraining force (tag effect) of the crossing belt layer 18 becomes too strong in the vicinity of the tire equator plane, Disadvantageous against fever.
On the other hand, when the angle of the cord 19 with respect to the tire circumferential direction exceeds 100 ° on the tire equatorial plane CL, the inclination direction of the cord is reversed at the portion exceeding 90 °. Is difficult to bend and it is difficult to produce a cross belt layer.

Next, when the angle αs of the cord 19 with respect to the tire circumferential direction is less than 20 ° at an intermediate position between the end portion of the spiral belt layer 20 and the tread end 24E, the restraining force (tag effect) of the crossing belt layer 18 is increased. It becomes too strong on the side, and it becomes impossible to secure a ground contact area necessary for securing a grip in a large camber region.
On the other hand, when the angle αs of the cord 19 with respect to the tire circumferential direction exceeds 80 ° at an intermediate position between the end portion of the spiral belt layer 20 and the tread end 24E, the restraining force (tag effect) of the cross belt layer 18 on the tread end side. Becomes too small to suppress the standing wave.

In the above embodiment, the crossing belt layers are two layers, but in some cases, three or more layers may be used.
Moreover, the said embodiment is an example of this invention and can be variously changed and implemented within the range which does not deviate from the summary. It goes without saying that the scope of rights of the present invention is not limited to these embodiments.

(Test example)
In order to confirm the effect of the present invention, the present inventor prepared two types of tires according to the embodiment to which the present invention was applied and three types of conventional tires, and used a racing motorcycle with a displacement of 1000 cc for the circuit. An actual vehicle test was conducted to evaluate cornering grips and cornering stability, and a standing wave and high-speed durability test were performed using an indoor drum tester.

Examples 1 and 2: As described in the above-described embodiment, the pneumatic tire for a motorcycle has a structure in which the cord angle of the crossing belt layer is set to be large on the tire equator side and small on the tread end side. The first embodiment and the second embodiment have different cord angles as shown in Table 1 below.
Conventional Examples 1-3: A pneumatic tire for a motorcycle having a structure in which the cord angle of the crossing belt layer is constant. Conventional examples 1 to 3 have different cord angles and spiral belt layer widths as shown in Table 1 below.
The tire sizes of the test tires are 190 / 55R17M / C, and the tread surface distance L from the tire equator surface to the tread end of the tread portion is 120 mm.

For evaluation of cornering grip and cornering stability, riders evaluated each tire by a 10-point scale method by feeling.
・ Standing wave: Feeling evaluation by riders at the standing wave generation speed.
-High speed durability: According to the drum test method according to JIS standards. The speed was stepped up at regular intervals, and the speed before the tire broke down was evaluated. The evaluation was a 10-point full scale evaluation, with 1 point being 5 km / h based on 8 points. For example, 2 points are 5 × (8-2) = 30 km / h, and the durability speed is 30 km / h lower than that of 8 points.
The results are as shown in Table 2 below.

試験の結果から、本発明の適用された実施例１，２のタイヤは、コーナリンググリップ、コーナリング時安定性、スタンディングウェーブの抑制、高速耐久性を両立できていることが分かる。

From the test results, it can be seen that the tires of Examples 1 and 2 to which the present invention is applied are compatible with cornering grip, cornering stability, suppression of standing wave, and high-speed durability.

It is sectional drawing along the rotating shaft of the pneumatic tire for two-wheeled vehicles which concerns on one Embodiment of this invention. (A) is a plan view schematically showing the first belt ply (only the code is shown), and (B) is a plan view schematically showing the second belt ply (only the code is shown). It is a schematic diagram which shows the state which piled up each code | cord | chord of a 1st belt ply, a 2nd belt ply, and a spiral belt layer. (A) is a plan view schematically showing a first belt ply of a conventional tire (only the code is shown), and (B) a plan view schematically showing a second belt ply of a conventional tire ( Code only). It is a schematic diagram which shows the state which piled up each code | cord | chord of the 1st belt ply, 2nd belt ply, and spiral belt layer of the tire of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Pneumatic tire for two-wheeled vehicles 12 Bead part 14 Bead core 16 Carcass 18A 1st belt ply 18B 2nd belt ply 18 Crossing belt layer 19 Cord 20 Spiral belt layer 22 Auxiliary belt layer 24 Tread part 26 Tread rubber layer 26C Cap rubber layer 26B Base Rubber layer L Red surface distance

Claims (3)

A carcass composed of at least one ply straddling a toroidal pair of left and right bead cores;
It is composed of two or more belt plies including a plurality of cords that are arranged on the outer side in the tire radial direction of the carcass and inclined with respect to the tire circumferential direction, and the cords of the belt plies adjacent to each other are in the tire circumferential direction. Cross belt layers inclined in opposite directions,
A spiral belt layer including a cord that is arranged on the outer side in the tire radial direction of the crossing belt layer and wound spirally;
A tread rubber layer disposed outside the spiral belt layer in the tire radial direction and constituting a tread portion;
The angle of the belt ply cord with respect to the tire circumferential direction is set such that the belt end side is smaller than the tire equatorial plane side,
The width of the crossing belt layer is set wider than the spiral belt layer,
When the tread surface distance from the tire equator surface to the tread end of the tread portion is L, and the length from the tire equator surface to the ply end of the spiral belt layer is B, 0.5L ≦ B ≦ 0.8L A pneumatic tire for a motorcycle characterized by being satisfied.   2. The pneumatic tire for a motorcycle according to claim 1, wherein the cord of the crossing belt layer has an angle with respect to a tire circumferential direction within a range of 45 to 100 ° on a tire equatorial plane.   The cord of the crossing belt layer has an angle with respect to a tire circumferential direction within a range of 20 to 80 ° at an intermediate position between an end portion of the spiral belt layer and a tread end. 2. A pneumatic tire for a motorcycle according to 2.

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