JPH04321404A - Tire for motor-cycle - Google Patents

Abstract

PURPOSE:To enhance the traction and to prevent occurrence of block-chunking. CONSTITUTION:In an on-road tire 1 for motor-cycles, the width B of a tread arcuately extending in the meridian direction from the equator plane, gives a maximum width of the tire, and a belt layer which is laid outside of a carcass 3 in substantially parallel with the equator plane of the tire, is formed of aromatic polyamide fiber cords wound on a joint, the center part of the tread section 2 being formed in a rugged pattern 5 having a pattern angle theta which is set as 45deg. <=theta<=75deg. with respect to the equator.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an improvement in the structure of a tread portion of a pneumatic tire for a motorcycle.

0002

2. Description of the Related Art A pattern as shown in FIG. 6, for example, is formed on the tread portion of a conventional motorcycle tire. That is, a groove 21 is formed along the equatorial plane in the tread portion 2, and grooves 22 independent from the groove 21 are formed on both sides of the groove 21, and the groove 22 has an angle with respect to the equatorial plane near the center of the tread portion 2. θ is 20
It is set at around 100°. That is, both side portions are similar to a lug pattern, but the center portion is formed in a rib pattern type.

0003

In the above structure, although the rib pattern exhibits a lateral slip prevention effect, it has the disadvantage that traction performance is insufficient. If a lug pattern is adopted in the center part to improve traction performance, there is a risk of block chunking (chipping) occurring during high-speed driving. For this reason, in high-speed tires, it has not been possible to adopt a lug pattern only in the central portion of the tread portion 2 as described above.

The present invention has been made to eliminate these conventional drawbacks, and provides a motorcycle that employs a lug pattern in the center part to improve traction performance and is free from the risk of block chunking. The purpose is to provide tires for

[0005]

[Means for Solving the Problems] The present invention provides an on-road tire for motorcycles in which the tread extends in an arch shape from the equatorial plane to both sides in the meridian direction, the tread width is the maximum width of the tire, and the carcass ply is On the outside, the cords of the belt layer are arranged substantially parallel to the equatorial plane of the tire, and this belt layer is formed by jointless wrapping of aromatic polyamide fiber cords, and the central part of the tread section is arranged in a lug pattern or oblong block. The pattern is configured such that the pattern angle θ with respect to the equator satisfies 45°≦θ≦75°.

[0006]

[Function] In the above structure, the cord layer formed by jointless winding of the aromatic polyamide fiber cord suppresses tire growth during high-speed running and prevents block chunking. The lug pattern in the center provides good traction performance.

[0007]

[Embodiment] In FIG. 1, an on-road tire 1 for a motorcycle has a tread portion 2 and sidewalls 4 extending inward in the tire radial direction from both ends of the tread portion 2. A carcass ply 3 is arranged inside, and both ends of the carcass ply 3 are folded back around a bead core 31 embedded in the inner end of the sidewall 4. This carcass ply 3 is at least 1
More than 70 to 9 organic fiber cords to the tire equator
It is arranged and configured at 0°.

The tread portion 2 extends in an arch shape from the equatorial plane to both sides in the meridian direction, the tread width B is the maximum width of the tire, and a belt layer 30 is provided on the outside of the carcass ply 3 substantially parallel to the equatorial plane of the tire. This belt layer 3
0 is a low twist made of aromatic polyamide fiber (24~2
It is formed by winding a jointless cord of 9T/10cm). By configuring the belt layer 30 in this manner, the tightening force against the carcass ply 3 can be increased and elongation can be minimized. Therefore, growth of the tire during high-speed driving can be suppressed, and block chunking can be prevented.

Further, the tread portion 2 is formed with grooves 5 as shown in FIG. This groove 5 includes a central groove 51, a side groove 53 that extends continuously from this side end to one side end of the tread portion 2, a central groove 52 arranged parallel to the central groove 51, and each of the central grooves. The grooves 5 are arranged symmetrically, and the center grooves 51 and 52 of the left and right grooves are arranged alternately to form a center part. Formed in a lug pattern. Furthermore, a short independent groove 55 is formed on the side of the side groove 54. and central groove 5
The inclination angle θ with respect to the equator of Nos. 1 and 52 is both set to about 60°.

FIG. 3 shows another embodiment of the present invention, in which a first groove 61 is arranged in a linearly inclined manner only in the center part of the tread portion 2, and a first groove 61 is disposed in a linearly inclined manner only in the center part of the tread part 2, and a first groove 61 is arranged continuously from the center part of the tread part 2. V-shaped grooves 6 including second grooves 62 extending linearly to the ends with an inclination opposite to that described above are arranged symmetrically and alternately, and the center portion is formed in a lug pattern. The inclination angle θ of the first groove 61 and the second groove 62 with respect to the equator is approximately 60.
° is set.

FIG. 4 shows still another embodiment of the invention,
A first groove 71 is arranged in a V-shape symmetrically in the center of the tread portion 2, and a second groove 71 extends in a straight line from the side end of the groove 71 to the end of the tread portion 2. A substantially V-shaped groove 7 consisting of a groove 72 is arranged, and the center portion is formed in a lug pattern. The inclination angle θ of the first groove 71 with respect to the equator is set to about 70°.

FIG. 5 shows still another embodiment of this invention,
A first groove 81 is arranged linearly at the center of the tread portion 2 and inclined in one direction, and a first groove 81 extends linearly from both side ends of the groove 81 to the ends of the tread portion 2, perpendicular to the equator. A groove 8 consisting of a second groove 82 is arranged, and the center portion is formed in a lug pattern. The inclination angle θ of the first groove 81 with respect to the equator is set to about 60°.

As in each of the above embodiments, by forming a lug pattern in the center of the tread portion 2 and setting the pattern angle θ with respect to the equator within an appropriate range, good traction performance can be exhibited and the lug pattern can be No block chunking occurs. Similar effects can be achieved if the pattern angle θ is within the range of 45°≦θ≦75°. When θ is less than 45°, the traction performance deteriorates, and when it is more than 75°, soil removal and drainage performance deteriorates. A horizontally long block pattern may be adopted at the side end portions of the tread portion 2 instead of the above-mentioned lug pattern.

Next, Table 1 shows the results of comparing the performance of the tire with the configuration shown in FIG. 2 and the tire with the conventional structure.

[0015]

[Table 1]

In Table 1 above, nylon 2/1260d was used for the carcass ply. Further, the pattern uses the pattern configuration shown in FIG. 2 or the pattern configuration shown in FIG. 6, respectively, and the ground contact area is shown as a ratio when the conventional product is set as 100. As is clear from this table, the ground contact area of the inventive product is 20% larger than that of the conventional product, the dynamic outer diameter growth is significantly smaller than that of the conventional product, and chunking does not occur as a result of continuous high-speed running. I couldn't see it.

[0017]

As explained above, according to the present invention, the cord layer formed by winding the aromatic polyamide fiber cord in a jointless manner suppresses tire growth during high-speed running, thereby reducing block chumps during high-speed running. Kinging is prevented from occurring, and good traction performance is exhibited due to the lug pattern at a predetermined angle formed in the center of the tread.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional shape diagram taken along line A-A in FIG. 2 of a tire showing an embodiment of the present invention.

FIG. 2 is a partial plan view showing a pattern of a tread portion.

FIG. 3 is a partial plan view showing another example of the pattern of the tread portion.

FIG. 4 is a partial plan view showing another example of the pattern of the tread portion.

FIG. 5 is a partial plan view showing still another example of the pattern of the tread portion.

FIG. 6 is a partial plan view showing an example of a conventional tread pattern.

[Explanation of symbols]

1 Tires 2 Tread part 3 Carcass ply 30 Belt layer

Claims (1)

[Claims] Claim 1: An on-road tire for motorcycles, in which the tread extends in an arch shape from the equatorial plane to both sides in the meridian direction, the tread width is the maximum width of the tire, and the cords of the belt layer are attached to the outside of the carcass ply. The belt layer is formed by jointless winding of aromatic polyamide fiber cords, and the central part of the tread has a lug pattern or a horizontal block pattern with a pattern angle θ relative to the equator. 45°≦θ
A motorcycle tire characterized by being configured such that the angle is ≦75°.