JPH03204305A - Tire for motorcycle - Google Patents

Abstract

PURPOSE:To improve performance both in straight traveling and in turning traveling by forming the block pattern forming a tread surface in such a way that the block groups formed along the outer circumferential surface consisting of two circular arcs of different radii of curvature in a specific relationship in the meridian plane including the tire axis are alternately arranged in the circumferential direction. CONSTITUTION:A circular arc 9 of a radius of curvature R1 passing through the equator point Q1 and having its center on the equator plane CO of the tire in the meridian plane including the tire axis, and a second circular arc 10 of a radius of curvature R2, that is greater than 1.1 times and less than 1.5 times the radius of curvature R1, passing through the equator point Q2 in the same radial position are assumed. The first block groups 11 and second block groups 12 whose outer surfaces are formed along the first and second circular arcs 9, 10 respectively are alternately and dividedly arranged in the circumferential direction of the tire for forming a block pattern A. By this constitution, performance both in straight traveling and in turning traveling can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a motorcycle tire that can improve both straight running performance and cornering performance, and can be particularly suitably used for running on rough terrain.

[Conventional technology]

Motorcycle tires for running on rough terrain and for both level and rough terrain generally have multiple blocks arranged on the tread surface to improve traction on rough roads such as rough ground, sandy land, muddy ground, etc. A block pattern is formed.

On the other hand, due to the dynamic characteristics of motorcycles, it is necessary to tilt the tires at a deep bank angle when turning, and therefore, the tread surface, that is, the outer surface of the block, has traditionally been made with a simple structure to smooth the transition from straight-ahead driving to cornering. It is formed by one circular arc.

[Problem to be solved by the invention]

However, in conventional tires having such a single circular arc, there is a problem in that it is difficult to simultaneously improve both straight running performance and cornering performance.

In other words, when the radius of curvature of the arc is set relatively large, it is possible to improve ground contact when traveling straight and exhibit high straight running performance, but on the other hand, it is difficult to tilt the tire into a deep bank angle, which reduces cornering performance. decrease.

On the other hand, if the radius of curvature is made small, the ground contact will be impaired and the straight running performance will be reduced.

The present invention defines a first group of blocks whose outer surfaces follow a first circular arc and a second group of blocks whose outer surfaces follow a second circular arc having a radius of curvature larger than the first circular arc to form a tire circle. It is an object of the present invention to provide a motorcycle tire that can solve the above-mentioned problems by basically arranging the tire in sections in the circumferential direction.

[Means to solve the problem]

In order to solve the above problems, the motorcycle tire of the present invention includes a block pattern in which a plurality of blocks are formed on a trend plane, and the block pattern is arranged in a meridian plane including the tire axis and in the tire equatorial plane. a first block group consisting of a plurality of adjacent first blocks whose outer surfaces are along a first circular arc with a radius of curvature R1 having a center and passing through the tire equator point; It passes through a tire equator point at the same radial position as the tire equator point, and the radius of curvature R2 is set to 1.
A second block group consisting of a plurality of adjacent second blocks whose outer surfaces follow a second circular arc that is 1 times or more and 1.5 times or less is divided and arranged in the tire circumferential direction. There is.

[Effect]

The first block group of the motorcycle tire configured in this way has an outer surface of the first block group having a small radius of curvature R1.
Since the second block group is formed along a circular arc, it has high turning performance, and since the second block group is formed along a second circular arc with a large radius of curvature R2, it has excellent straight-line performance. Therefore, in a tire in which these are divided and arranged in the circumferential direction, when the vehicle is traveling straight, the first and second block groups alternately contact the ground, and when the second block group contacts the ground, the straight travel can be stabilized. Furthermore, by cutting off both ends of the second group of blocks within the straight-ahead ground contact area, the tire can be tilted in at a deep bank angle by the first group of blocks that make contact with the ground during a turn, improving cornering performance.

In addition, the first and second block groups are divided in the circumferential direction, and the outer surfaces of each block are formed along a single first and second circular arcs, making it possible to smoothly transition between going straight and turning. can be converted into
Overall driving performance can be greatly improved.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

In the figure, a motorcycle tire 1 includes a pair of bead portions 3 through which a bead core 2 passes, a sidewall portion 4 extending outward in the tire radial direction from the bead portions 3, and a tread portion 5 connecting the outer ends of the sidewall portions 4. This is a toroidal pneumatic tire with a tread portion 5 between the bead portions 3 and 3.
The carcass 6, which is folded back around the bead core 2 through the sidewall portion 4 and retained thereon, is passed over the rack, and a block pattern A is formed on the tread surface, which is the outer surface of the trend portion 5.

The block pattern A includes a first block group 11- whose outer surface follows the first circular arc 9, and a second block group 11- whose outer surface follows the first circular arc 9.
The plotter pattern A is divided into 12 blocks in the circumferential direction along
Each first and second block group in the range of ~26 11.12
By spacing them alternately at equal circumferential pitches P, they are formed with a uniform and high sea/land ratio. First,
The second block group 11, 12 can be provided with an unequal pitch in addition to the equal pitch P, and by adopting a barrier pull pitch, the impact noise, bumping noise, etc. caused by the tire when touching the ground can be prevented. Can reduce noise.

Further, the first arc 9 has its center on the tire equatorial plane CO in the meridian plane including the tire axis, and has its center on the tire equatorial point Q1.
In this example, the first block groups 11 are arranged in a substantially straight line adjacent to each other in the tire axial direction, and the outer surfaces of the blocks are arranged in a substantially straight line in the tire axial direction. A plurality of first blocks 13 curved along
formed from.

Further, the first blocks 13... need to be arranged over the entire ground contact area K including 1 in the turning ground contact area on the tread end side that makes contact with the ground during turning, and The outer surface of the small diameter first block 13 located at Kl enables the tire 1 to be tilted in at a deep bank angle,
Able to perform stable turning movements.

The second circular arc 10 has a center on the tire equator mCO, uses a tire equator point Q2 at the same radial position as the tire equator point Q1, and has a radius of curvature R2 that is 1.1 times or more the radius of curvature R1. and an arc of 1.5 times or less,
Similarly, in this example, the second block group 12 is a plurality of blocks that are arranged in a substantially straight line adjacent to each other in the tire axial direction, and whose outer surfaces are curved along the second circular arc lO.
In this example it is formed from two second blocks 14.14.

Further, the second block 14 is disposed within the straight ground contact area 2 that touches the ground when traveling straight among all the ground contact areas.

In this way, the block pattern A consists of the first and second block rows 11 arranged in two rows in the straight-ahead ground contact area when traveling straight.
．． 12 alternately repeats contact with the ground, and when the first block group 11 along the second circular arc 10 having a large radius of curvature R2 contacts the ground, the ground contact performance can be improved and straight running can be stabilized.

Also, since the first and second arcs 9.10 pass through the tire equator points Ql and Q2 at the same radial position, the step t between the first and second arcs 9.10 is defined as the tire equator points Ql and Q2. It gradually increases from t to the trend end, and therefore, while maintaining ride comfort, the change in ground pressure caused by the step t can improve traction.

In addition, in block pattern A, since the second block group 12 is interrupted within 2 in the straight-ahead ground contact area a, during turning, the first block 13 located at 1 in the turning ground contact area makes contact with the ground, resulting in poor ground contact. This makes it possible to tilt the tire in at a deep bank angle.

Further, the first and second block groups 11.12 are divided in the tire circumferential direction, and each block group 11.12 is formed along one circular arc 9.10, so that it is possible to change from straight running to turning. It is possible to smoothly transition the tire axial direction to driving.

Note that the boundary portions between the straight ground contact area 2 and the turning ground contact area 1 overlap each other, and the step t is formed at the boundary portion.
is formed.

However, in the present invention, by regulating the radius of curvature R2 to a range of 1.1 times or more and 1.5 times or less of the radius of curvature R1, it is possible to maintain ride comfort and smooth the transition to cornering. be enhanced.

That is, when the radius ratio R2/R1 exceeds 1.5, the step t
becomes excessive, which reduces the transferability between straight running and turning, impairs the riding comfort, and sometimes causes blocks to be missing in the first block 13, reducing durability.

Further, if the radius ratio R2/R1 is less than 1.1, the effect of improving both straight running performance and turning performance will be insufficient.

In this example, the first and second block groups 1
Between 1.12 and 1.12, a first sub-block 13A whose outer surface is arranged along the first circular arc 9 and within the turning ground area Kl is attached to further enhance the grounding stability during turning.

In the present invention, if the block groups 11.12 are adjacent to each other in the tire axial direction, the block groups 13.1 and 13.12 may be linear, for example, as shown in FIG. 3 (al to (b)).
4 can be formed in a staggered manner or in multiple rows in the circumferential direction, and in addition to the first and second block groups 11 and 12, the block pattern A can also be formed in the third and fourth blocks. Further counties may be added, and such other third and fourth districts may be added.
- Each block constituting the block group has a third and fourth outer surface with a radius of curvature of 01 or more and
Formed along the arc of...

〔Concrete example〕

The tire size with the tire structure shown in Figures 1 and 2 is 11.
A prototype tire of 0/100-18 was attached to the rear wheel of a 250cc motocrosser, and its running performance and trough silane performance were compared with conventional tires. The driving performance was evaluated using the average lap time of actual vehicle driving on a motocross course. In addition, the performance of trough silane is confirmed when the vehicle is fixed on an unpaved road surface.1. When the vehicle is fixed to the supporting jig via a tension type load cell and the accelerator is gradually opened with the first gear engaged, slipping occurs. The maximum driving force generated up to this time was evaluated using an index with the conventional tire set as 100. Conventional tires with a tire size of 80/100-21 were installed on the front wheels.

〔Effect of the invention〕

Like a ridge, the motorcycle tire of the present invention has a first group of blocks in which the outer surface of the blocks follows a first circular arc with a small radius of curvature, and a second group of blocks in which the outer surface of the blocks follows a second circular arc with a large radius of curvature. Because the second block group is divided and arranged in the tire circumferential direction, the tire is simultaneously given both high turning performance and straight-line performance while maintaining transition performance between straight-ahead driving and turning. sell.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, FIG. 2 is a developed view showing the block pattern, and FIG. 3(a) to 3) are route maps showing other embodiments of the block group. 1 9...-first arc, 10...-second arc, 11...-first block group, 12...-second block group, 13...-first block, 14 A...Block pattern, Ql, Q2-...-Tire equator point. second block,

Claims (1)

[Claims] 1. A block pattern including a plurality of blocks formed on the tread surface is provided, and the block pattern has a first radius of curvature R1 having a center on the tire equatorial plane and passing through the tire equatorial point in a meridian plane including the tire axis. A first block group consisting of a plurality of adjacent first blocks whose outer surfaces follow a circular arc, and a first block group having a center on the tire equatorial plane and passing through a tire equator point at the same radius position as the tire equator point and having a curvature. The radius R2 is 1.1 of the radius of curvature R1.
A second block group consisting of a plurality of adjacent second blocks whose outer surfaces follow a second circular arc that is at least twice as large and no more than 1.5 times larger is divided and arranged in the tire circumferential direction. Motorcycle tires.