JPH0655909A - Tire for motor-bicycle - Google Patents

Abstract

PURPOSE:To improve straight running performance and turning performance of a time at the same time and to enable the tire to be acceptable as a suitable tire for a motor-bicycle running across a snowy are and a Ma non-snowy area by improving drainage performance during running on a wet road surface. CONSTITUTION:Multiple groove parts 3... are provided on a tread face 2, while within an angle range of 0-40 ' of a camber angle, the ratio of the total groove areas inside a ground contact area to a ground contlet area 4, EGG/Ss, is set to be 0.25-0.40 and the number of inlet/outlet ends, in which the grooves are opened on the kick out side of the ground contact area, is set to be 4-15.

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 capable of improving running stability when traveling straight and turning by improving drainage when running on a wet road surface.

[0002]

2. Description of the Related Art In the case of motorcycle tires,
At the time of fine weather, the driving stability has been improved mainly in high speed running on a paved road during dry weather.

[0003]

However, due to the recent development of highways, even motorcycles have more opportunities to run across snowy areas and non-snowy areas, and also make sharp turns even during rainfall. The tires are often used under severe conditions.

Further, unlike a passenger car or a bus / truck, a motorcycle travels with a bank angle when turning, so that the position of the ground contacting the road surface of the tire moves. Therefore, as a tire for a motorcycle, it is necessary to maintain the grip force and the braking force even when the bank angle changes.

As a result of intensive research conducted by the inventor to find a tire that meets such a use condition, (1) even if the bank angle changes, the ratio of the groove portions on each ground contact surface is constant. Be within range. (2) The number of open ends of the groove located on the kicking side is restricted in each ground contact state. It has been found that the stability of traveling can be maintained when traveling on a wet road surface.

An object of the present invention is to provide a motorcycle tire capable of stabilizing straight running performance and turning performance when traveling on a wet road surface and expanding an applicable range.

[0007]

DISCLOSURE OF THE INVENTION The present invention is a motorcycle tire in which a tread surface has an arc shape in a tire meridian section and a plurality of groove portions are provided on the tread surface,
The camber angle is 0 degree or more and 40 or less in a normal state where the camber angle is attached to the regular rim and the regular internal pressure and the regular maximum load are applied.
The ratio ΣGs / Ss of the sum ΣGs of the groove areas in each grounding surface and the area Ss of the grounding surface that are grounded to the road surface in an angle range of not more than 0.25 degrees and 0.40 or less The tire for a motorcycle is characterized in that the number of outlet ends of the groove portion located in each of the contact surfaces is 4 or more and 15 or less at the periphery of the contact surface and opens toward the kicking side.

[0008]

When the camber angle is in the range of 0 degree to 40 degrees, the ratio ΣGs / Sc of the sum ΣGs of the groove areas in each contact surface to the area Ss of the contact surface and the groove portion at the peripheral edge of the contact surface. The number of exits on the kicking side is regulated.

By thus regulating the camber angle in the range of 0 to 40 degrees, when the motorcycle goes straight ahead,
In either case, the grip force and the braking force can be maintained at substantially constant values.

When the area ratio ΣGs / Ss is less than 0.25, the grip force is poor during traveling on a wet road surface, the steering stability during wet is deteriorated, and the rainwater adhering to the tread surface is sufficiently discharged by the groove. If this is not possible, slip will occur and braking force will be poor. Also, the ratio ΣGs / Ss
Is more than 0.40, the ground contact pressure on the ground contact surface increases, resulting in accelerated wear of the tread surface and poor durability.

On the other hand, when the number of the entrances and exits is less than 4, rainwater is not completely discharged from the groove as described above,
The wet braking force is reduced, resulting in poor steering stability. On the other hand, if the number of outlet ends exceeds 15, the number of grooves in the groove increases, and the rigidity of the ribs or blocks formed in the feel of the groove decreases, and as a result, uneven wear is likely to occur at the groove edges, resulting in poor durability. Becomes

As described above, according to the present invention, since the above-mentioned constitutions are organically combined and integrated, the steering stability can be improved when traveling on the wet road surface regardless of whether the vehicle is going straight or turning. is there.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of this embodiment will be described below with reference to the drawings in comparison with a conventional tread pattern shown in FIG. 1 to 4, a motorcycle tire 1
Indicates that the tread surface 2 has an arc shape in the meridional section,
Moreover, a plurality of groove portions 3 ... Are provided on the tread surface 2.

Further, the motorcycle tire 1 includes sidewall portions 13 extending inward in the tire radial direction from both ends of a tread portion 12 having the tread surface 2 as an outer peripheral surface,
A bead portion 1 connected to an inner end of the sidewall portion in the radial direction
4, the tire 1 for a motorcycle has a carcass 16 that is folded back around the bead core 15 of the bead portion 14 from the tread portion 12 through the sidewall portion 13 and inside the tread portion 12 and outside in the radial direction of the carcass 16. And a belt layer 17 disposed on the.

In the present embodiment, the carcass 16 comprises at least one carcass ply, which in this embodiment comprises a carcass cord of radial or semi-radial arrangement inclined at an angle of 75 to 90 ° with respect to the tire equator C, and in the present embodiment, one carcass ply. As the carcass cord, organic fiber cords such as nylon, rayon, polyester and aromatic polyamide are used.

The belt layer 17 is composed of one or a plurality of, in this embodiment, two belt plies, and each belt ply is made of an organic fiber such as nylon, rayon, polyester, rayon, aromatic polyamide or a steel cord. The belt cords are arranged at a relatively shallow angle with respect to the tire equator C, and the cords of each ply are inclined so as to intersect with each other.

A plurality of groove portions 3 ... Are provided on the tread surface 2. In the present embodiment, the groove portions 3 ...
A central vertical groove 3A that circulates on the tire equator C, one edge E of the tread portion 12 starting from the vicinity of the tire equator C
1 and the other end edge E2 as an open end, the oblique grooves 3B extending symmetrically in a V shape and arranged side by side in the tire circumferential direction.
B .... and bypass grooves 3C ... Connecting the two oblique grooves 3B, 3B adjacent to each other in the circumferential direction, respectively.

The tread surface 2 having the tread pattern composed of such groove portions 3 ... In the normal state in which the tire 1 is mounted on the regular rim J and the regular internal pressure and the regular maximum load specified for the tire are applied. When the camber angle α is 0 degree, the tire 1 comes in contact with the road surface L with
The range is indicated by the one-dot chain line in the figure. The camber angle α is the inclination of the equatorial plane C of the tire with respect to the normal line N of the contact surface L as shown in FIG.

Further, in the tire having the oblique groove 3B having the above-mentioned structure, when mounted on a vehicle, one end A1 close to the tire equator is opened to the driving side F of the tire and the tread edge E1 (E2). The other end F2 is attached to the kicking side G. The groove width W of the oblique groove 3B is the same as the one end A
It is desirable to improve the drainage property by increasing the width from the 1 side toward the other end A2, that is, the tread edge side, or by gradually increasing the width.

The groove portions 3 ... Guide rainwater adhering to the tread surface 2 to the groove portions 3 when the vehicle travels on a wet road surface such as when it is raining, and from the exit end 5 on the kicking side G at the periphery of the ground contact surface 4. By releasing it, it is possible to improve the traction performance and the braking performance when traveling in the rain.

Moreover, since the tire for a motorcycle takes a turning posture peculiar to a motorcycle that turns with a large camber angle when turning, unlike a tire for a four-wheeled vehicle, during such turning, It is also necessary to maintain sufficient traction and braking force.

The oblique groove 3B is provided for the purpose of quick drainage, and the bypass groove 3C is formed with the intention of improving the traction force and the braking force during dry and wet conditions and also improving the drainage property. It is a thing.

In this embodiment, the groove width GW of the grooves 3 ... Is 0.04 to 0.12 of the tread width WT, and the groove depth GH is 0.06 to 0.18 times the tread width WT. Is preferably set to.

In FIG. 3, the tire size is 160 / 70V1.
No. 8 tire having the pattern shown in FIG. 1 (Example)
FIG. 6 shows a change in the pattern of the contact surface 4 when traveling with a camber angle during turning, and FIG. 6 shows a conventional tire having the same size as that of the above embodiment and having the tread pattern shown in FIG. The change in the pattern of the ground plane 4 in the comparative example) is shown respectively. Table 1 shows the total ratio ΣGs / Ss of the groove area to the ground contact area at each camber angle and the number of the groove portions on the kicking side in the ground contact surface.

[0025]

[Table 1]

In the thus formed example, the steering stability is improved by 25% when turning with a camber angle of 36 degrees, as compared with the comparative example.

Regarding the steering stability, the test tire is mounted on the regular rim and an internal pressure of 2.9 kg / cm ² is applied, and the tire is mounted on the front wheel of the motorcycle to run on the test course and It was judged by feeling. The determination result is shown by an index with the comparative example being 100. The larger the value, the better.

[0028]

As described above, in the pneumatic radial tire of the present invention, the ratio of the sum of the groove area in the ground contact surface to the area of the ground contact surface is ΣGs / in the angle range where the camber angle is 0 ° or more and 40 ° or less. Since Ss is 0.25 or more and 0.40 or less and the number of outlet ends where the groove portion opens on the kicking side of the ground contact surface is 4 or more and 15 or less, the straight traveling time and the camber angle can be reduced when traveling on a wet road surface. A motorcycle that can improve the drainage of the ground contact surface, improve the stability of running, and maintain the running performance on dry roads even when turning while imparting and running, and running across snowy areas and non-snowy areas. It can be suitably used as a tire for automobiles.

[Brief description of drawings]

FIG. 1 is a developed plan view showing a tread pattern according to an embodiment of the present invention.

FIG. 2 is an axial sectional view of the tire.

FIG. 3 is a front view showing a posture of a tire in a tilt running state.

4 (A), (B), (C), and (D) are plan views showing a ground contact surface of a tire together with a change in camber angle.

FIG. 5 is a developed plan view showing a pattern of a conventional tire.

6 (A), (B), (C), and (D) are plan views showing a contact surface of a conventional tire along with a change in camber angle.

[Explanation of symbols]

 2 Tread surface 3, 3A, 3B, 3C Groove portion 4 Ground contact surface 5 Entry / exit end G Launch side J Regular rim α Camber angle

Claims (1)

[Claims] 1. A motorcycle tire having a tread surface having an arc shape in a tire meridian section and having a plurality of grooves on the tread surface, the tire being mounted on a regular rim and being subjected to a regular internal pressure and a regular maximum load. In the normal state, the sum ΣGs of the groove areas in the respective ground planes that respectively contact the road surface in a state where the camber angle is in the range of 0 degree to 40 degrees
And the ratio ΣGs / Ss of the area Ss of the contact surface to 0.25 or more and 0.40 or less, and the groove portion located in each of the contact surfaces opens toward the kicking side at the peripheral edge of the contact surface. A motorcycle tire, characterized in that the number of outlet ends is 4 or more and 15 or less.