JP3245252B2 - Pneumatic tires for motorcycles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire for a motorcycle, and more particularly to a pneumatic tire for a motorcycle with improved turning performance.

[0002]

2. Description of the Related Art A conventional pneumatic tire for a motorcycle has a tread section having a single radius of curvature or an increase in the contact area when a large camber angle is imparted as shown in FIGS. It had two aimed radii of curvature R1 and R3 (> R1).

[0003]

By the way, in the conventional tire having a groove having the tread cross-sectional shape, a camber angle of 35 ° which is a limit use area on a wet road surface (a camber angle of about 1/4 point of the tread portion contacts the ground). When the vehicle traveled in the vicinity of (corner), the edge effect due to the pattern did not sufficiently appear due to the low contact pressure. For this reason, satisfactory drainage properties were not obtained, and the grip power and turning characteristics were not satisfactory.

[0004] A grooveless race tire (so-called slick tire) having the tread cross-sectional shape is used for a motorcycle for racing, and further improvement in grip force and turning force is required. .

In view of the above facts, the present invention is intended to improve the grip force and the turning characteristics in the camber area at the marginal use in rainy weather, and further, to improve the abrasion and handling during straight running, in the case of grooves, for racing. It is an object of the present invention to provide a pneumatic tire for a motorcycle that can improve the grip force and the turning force in the grooveless tire.

[0006]

According to a first aspect of the present invention, there is provided a motorcycle pneumatic tire including a pair of left and right bead portions, a carcass layer extending from one bead portion to the other bead portion, and a radial direction of the carcass layer. A belt layer disposed outside, and a tread portion disposed radially outside the belt layer,
And the crown radius of the tread center portion is R1,
When the crown radius near the quarter point of the tread is R2 and the crown radius of the tread shoulder is R3,
It is characterized in that the relationship among R1, R2 and R3 is R2 <R1 <R3.

The pneumatic tire for a motorcycle according to a second aspect of the present invention is the pneumatic tire for a motorcycle according to the first aspect, wherein a portion near a quarter point of a tread having the crown radius R2 is in contact with the ground during straight running. It is characterized by.

[0008] The pneumatic tire for a motorcycle according to claim 3 is the same as the pneumatic tire for a motorcycle according to claim 1 or 2, except that the pneumatic tire at 35 ° when the vehicle turns .
Also, in the contact portion at the time of applying a large camber angle, the vicinity of a quarter point of the tread having the crown radius R2 is located outside the contact center in the turning radial direction.

[0009]

The pneumatic tire for a motorcycle according to claim 1,
When the crown radius of the tread center portion is R1, the crown radius near the quarter point of the tread is R2, and the crown radius of the tread shoulder portion is R3, R1, R
The relationship between R2 and R3 is R2 <R1 <R3.

In the case of the grooveless tire, when the camber angle shifts from 0 ° to 35 ° due to turning, the ground contact area shifts from the tread center portion of the crown radius R1 to near the quarter point of the crown radius R2. The contact width becomes narrow. For this reason, the contact surface pressure at the contact center becomes higher than that of the conventional tire, and the contact length also increases.
Grip force increases, and turning performance improves.

In general, when the motorcycle turns on a wet road surface, the camber angle is around 35 °, which is the limit usage area. In this motorcycle pneumatic tire, around 1/4 of the tread is grounded. It will be. 1/4 of tread
The vicinity of the point is the part having the smallest radius of curvature in the tread, so that the contact pressure is high, and in the case of a grooved tire, the edge effect and drainage performance are improved, thereby gripping on a wet road surface, turning The characteristics are improved.

[0012] In the pneumatic tire for a motorcycle according to the second aspect, during straight running, the tread center portion having the radius R1 and the tread center portion near the quarter point of the radius R2 on both sides thereof contact the ground. . For this reason,
The contact length near the 1/4 point having the smallest radius of curvature in the tread of the tread is longer than the contact length near the 1/4 point of the conventional tire. As a result, straight running stability is improved, and handling is improved. In addition,
The reason why the contact length in the region near the 点 point on the contact surface is extended is that when the deformation in the width direction of the tire approaches the limit, the contact region does not expand any more and escapes as circumferential deformation.

Further, since the contact pressure in the region near the 1/4 point having the smallest radius of curvature of the tread in the contact surface is increased, uneven wear which occurs from the contact center of the tire to the outside is increased. Uneven wear caused by the diameter difference) is suppressed, and the wear resistance of the tire is improved.

Further, in the pneumatic tire for a motorcycle according to the third aspect, when turning at a camber angle larger than 35 ° , the vicinity of the quarter point where the contact pressure is high is located outside the contact center in the turning radial direction. , The restoring torque increases. As a result, the feeling of stepping on the tire itself is increased, steering stability during turning is improved, and turning characteristics can be improved from the beginning of turning to a large camber region.

[0015]

【Example】

[First Embodiment] The first embodiment of the pneumatic tire for a motorcycle according to the present invention.
An embodiment will be described with reference to FIGS.

As shown in FIG. 1, a pneumatic tire 10 for a motorcycle according to this embodiment has a pair of left and right bead portions 12 and a side portion 14 from one bead portion 12 to the other bead portion 12.
, A carcass layer 18 composed of one carcass ply 16 extending through the belt, a belt layer 20 disposed radially outside the carcass layer 18, and a tread portion 22 disposed radially outside the belt layer 20. ing.

The nylon cord of the carcass ply 16 is inclined at an angle of 90 ° with respect to the tire equatorial plane CL.

The belt layer 20 includes a first belt ply 20A on the inner side in the radial direction, a second belt ply 20B on the outer side in the radial direction of the first belt ply 20A, and an outer layer on the radial direction in the second belt ply 20B. And a third belt ply 20C.

In this embodiment, the cord material of the first belt ply 20A is nylon, and the cord of the second belt ply 20A is made of nylon.
The material of the cords of B and the third belt ply 20C is Kevlar.

The cord of the first belt ply 20A is inclined at an angle of 25 ° with respect to the tire equatorial plane CL, and the cord of the second belt ply 20B is
0A code, the first with respect to the tire equatorial plane CL
It is inclined at an angle of 25 ° symmetrically with the cord of the belt ply 20A.

The cord of the third belt ply 20C intersects with the cord of the second belt ply 20B, and is inclined at an angle of 25 ° with respect to the tire equatorial plane CL symmetrically with the cord of the second belt ply 20B. I have.

The tread portion 22 extends along the carcass contour with a substantially equal thickness from the center of the crown portion to the side end position 18A which forms the maximum width of the tire, outside the crown of the carcass layer 18.

Here, the pneumatic tire 10 for a motorcycle is
The crown radius of the tread center portion 22A is R1, and a position away from the tire equatorial plane CL by １ ／ of the tread width W outward in the tire width direction (direction of arrow A), that is, a quarter point 22B of the tread portion 22B. When the crown radius of the vicinity is R2 and the crown radius of the tread shoulder portion 22C is R3, the relationship GA2 <R2 between R1, R2 and R3 <
R1 <R3, and when traveling straight ahead, 1 /
Four points 22B near the ground, camber larger than 35 °
When the vehicle turns at a negative angle , the vicinity of the 1/4 point 22B is located outside the center of contact with the ground in the turning radial direction.

In this embodiment, the crown radius R1 is 88 m
m, R2 are 78 mm, and R3 is 160 mm.

Next, the operation of this embodiment will be described. In the pneumatic tire 10 for a motorcycle according to the present embodiment, during straight running, the tread center portion 22A closer to the tread center portion 22A of the tread center portion 22A of the radius R1 and the quarter point 22B of the radius R2 on both sides thereof is grounded. Become. For this reason, the pneumatic tire 10 for a motorcycle according to the present embodiment has a ground contact length near the tread center portion 22A near the quarter point 22B having the smallest radius of curvature of the tread in the tread surface of the conventional tire. It is longer than the contact length, so that the straight running stability is improved and the handling property is improved.

When the camber angle shifts from 0 ° to 35 ° due to the turning, the ground contact area becomes the crown radius R1.
From the tread center portion 22A to the vicinity of the quarter point 22B of the crown radius R2, and the contact width becomes narrow. Therefore, the pneumatic tire 10 for a motorcycle according to the present embodiment has a higher contact pressure at the contact center and a longer contact length than the conventional tire (see FIGS. 2A and 2B). Thereby, the grip force is increased, and the turning performance is improved.

Further, when the camber angle shifts to an angle larger than 35 ° due to a sudden turn, a high-speed turn, or the like, as shown in FIG. ) 26 to the outside in the turning radial direction (direction of arrow B) and the peak area of the contact pressure (R2 area)
The contact length is longer than that of the conventional tire, and the grip force is increased by these actions, and the turning force is improved.
Further, in this case, since the restoring torque is improved, the feeling of stepping on the tire itself is increased, and the steering stability during turning is improved.

As described above, the pneumatic tire 10 for a motorcycle according to the present embodiment has improved turning characteristics from the initial turn to a camber region larger than 35 ° .

Furthermore, in the pneumatic tire 10 for a motorcycle according to the present embodiment, since the contact pressure in the region near the quarter point 22B of the contact surface is increased, the bias generated from the contact center of the tire toward the outside is increased. Wear (uneven wear caused by diameter difference)
Is suppressed, and wear resistance is improved.

Second Embodiment A second embodiment of the pneumatic tire for a motorcycle according to the present invention will be described with reference to FIG. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 4, the motorcycle pneumatic tire 10 of this embodiment is an example in which a circumferential groove 30 is provided in the motorcycle pneumatic tire 10 of the first embodiment.

The circumferential groove 30 is formed in the tread center portion 2.
On the tire equatorial plane CL of 2A, near 1/4 point 22B and 1
It is provided at an intermediate portion between the / 4 point 22B and the tread end 18A. The other configuration is the same as that of the first embodiment.

Generally, the camber angle in turning on a wet road surface of a motorcycle is around 35 ° as the limit use area. In the pneumatic tire 10 for a motorcycle according to the present embodiment, a 1/4 point 22B that is grounded near a camber angle of 35 °.
A circumferential groove 30 is provided in the vicinity.
Since the contact pressure in the vicinity of 2B is increased, the drainage performance can be improved by increasing the edge effect in the limit use area near the camber angle of 35 °, and the grip performance and turning performance on a wet road surface can be improved. it can. [Test Example] In order to confirm the effects of the present invention, a pneumatic tire for a motorcycle according to the present invention shown in FIG. 1 (the pneumatic tire for a motorcycle 10 of the first embodiment) shown in FIG. 1 and a motorcycle shown in FIG. A total of four kinds of test tires are prepared: a pneumatic tire for use in motorcycles (the pneumatic tire for motorcycles 10 of the second embodiment) and two conventional pneumatic tires for motorcycles. A feeling test was conducted by a test rider attached to the rear. In addition, the conventional tire was attached to the front.

The test is performed separately for a grooved tire and a non-groove tire (slick tire). The grooved tire is tested for straight running stability and steering stability on a wet road surface, and the grooveless tire is tested for a dry road surface. Was tested for turning performance.

Table 1 below shows the test results of the grooved tire, and Table 2 shows the test results of the grooveless tire. The test results were scored by the 10-point method, and the larger the numerical value, the better the performance.

Here, a brief description will be given of the conventional pneumatic motorcycle tire used in the test. One of the conventional pneumatic tires for a motorcycle is a pneumatic tire 100 for a motorcycle without a groove shown in FIG. 5, and the other is a pneumatic tire 110 for a motorcycle with a groove shown in FIG. The crown radius R1 is 80 mm, and the radius of curvature R3 of the shoulder portions 22C on both sides of the tread center portion 22A is 110 mm.

As shown in FIG. 6, the conventional pneumatic tire 110 for a two-wheeled vehicle having a groove has a tread near the quarter point 22B and a quarter point 22B on the tire equatorial plane CL of the tread center portion 22A. A circumferential groove 30 similar to that of the second embodiment is provided at an intermediate portion with the end 18A.

The test conditions are as follows. "Test conditions" tire size: front 125/600-R17 rear 165/620-R17 internal pressure: Front 2.1kg / cm ² rear 2.3kg / cm ² load load: one person riding conditions

[0039]

[Table 1]

[0040]

[Table 2]

From the above test results, it is apparent that the grooved tire to which the present invention is applied has improved straight running stability and steering stability on a wet road surface, and the grooveless tire has improved turning performance. is there.

[0042]

As described above, the pneumatic tire for a motorcycle according to the first aspect has the above-mentioned structure. Therefore, in the case of the grooveless tire, when the camber angle shifts from 0 ° to 35 °, the center of contact with the ground is higher than that of the conventional tire. Since the contact surface pressure increases and the contact length increases, the gripping force increases, which has an excellent effect of improving turning performance.In the case of a grooved tire,
In the marginal use area near the camber angle of 35 °, there is an excellent effect that the edge effect and the drainage property are increased and the turning performance is improved.

The pneumatic tire for a motorcycle according to the second aspect has the above-mentioned structure, and therefore has excellent effects of improving straight running stability, improving handling properties and improving wear resistance.

Further, since the pneumatic tire for a motorcycle according to the third aspect is configured as described above, the steering stability at the time of turning a camber angle larger than 35 ° is improved, and a large camber is provided from the beginning of turning. It has an excellent effect that the turning characteristics can be improved up to the region.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a pneumatic tire for a motorcycle according to a first embodiment of the present invention.

FIG. 2 (A) shows the shape of the ground contact surface of the motorcycle pneumatic tire of the first embodiment at a camber angle of 35 °;
(B) shows the shape of the ground contact surface of the conventional motorcycle pneumatic tire at a camber angle of 35 °.

FIG. 3 is an explanatory diagram showing a contact surface shape and a contact pressure distribution at a large camber angle of the motorcycle pneumatic tire of the first embodiment.

FIG. 4 is a sectional view of a pneumatic tire for a motorcycle according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a conventional pneumatic tire for a motorcycle without a groove.

FIG. 6 is a cross-sectional view of a conventional pneumatic motorcycle tire having a groove.

[Explanation of symbols]

 Reference Signs List 10 Pneumatic tire for motorcycle 12 Bead part 18 Carcass layer 20 Belt layer 22 Tread part 22A Tread center part 22B 1/4 point 22C Tread shoulder part

Claims (3)

(57) [Claims] A pair of left and right bead portions; a carcass layer extending from one bead portion to the other bead portion; a belt layer disposed radially outside the carcass layer; Wherein the crown radius of the tread center portion is R1, the crown radius near the quarter point of the tread is R2, and the crown radius of the tread shoulder portion is R3.
A pneumatic tire for a motorcycle, wherein a relationship between 2 and R3 is R2 <R1 <R3. 2. The pneumatic tire for a motorcycle according to claim 1, wherein, when the vehicle is traveling straight, a quarter of the tread having the crown radius R2 is in contact with the ground. 3. In a contact portion at a camber angle larger than 35 ° when the vehicle turns, the vicinity of a quarter point of the tread having the crown radius R2 is closer to the turning radius direction than the contact center. 2. The method according to claim 1, wherein the outer side is provided.
Or the pneumatic tire for a motorcycle according to claim 2.