JP5497474B2 - Motorcycle tires - Google Patents

Description

  The present invention relates to a motorcycle tire, and more particularly to a motorcycle tire having excellent high-speed durability performance.

  A tire for a motorcycle is different from other vehicle tires such as a passenger car, a truck, and a bus in that it turns by generating a camber thrust. That is, the tread central portion is generally grounded during straight traveling of the vehicle, and the tread shoulder portion is generally grounded during turning. Therefore, motorcycle tires are required not only to ensure running stability during grounding over the entire tread, but also to have little noise difference between the central portion and the shoulder portion of the tread.

  As a motorcycle tire that satisfies such requirements, Patent Document 1 discloses a tread that has a corrugated groove in the center of the tread and an intermediate groove on the outer side in the axial direction of the corrugated groove, and that satisfies the above-described characteristics. A pattern has been proposed. These grooves naturally contribute to the improvement of drainage.

On the other hand, as one of the problems peculiar to motorcycle tires, there is a so-called shimmy that occurs around the front head during straight running. Various solutions to the Shimmy problem have been proposed, but it is well known to increase the thickness of the tread rubber, for example.
However, when the thickness of the tread rubber is increased, the distance between the center of the rubber and the tire surface that is in contact with the outside air at a lower temperature becomes longer and it is difficult to dissipate heat. This results in a decrease in durability, particularly high speed durability.

JP 2005-138807 A

  Therefore, the present invention relates to a tread having a groove extending in the shape of a wave at the center of the tread as described above, and even when the thickness of the tread rubber is increased to suppress the occurrence of shimmy, the high speed durability is reduced. The purpose is to propose a way to avoid it.

  In motorcycle tires, if the tread has a main groove extending in a wavy shape through a bend at the center of the tread, providing a secondary groove extending intermittently in the tread circumferential direction in the vicinity of the main groove will increase the high-speed durability. As a result, the present invention has been completed. Furthermore, it has also been found that the effect of the auxiliary groove is promoted by arranging the auxiliary groove on the side facing the main groove across the equator of the tire.

That is, the gist configuration of the present invention is as follows.
(1) In a motorcycle tire having a groove extending in a wave shape through a bend along the equator of the tire on the tread surface of the tire, the tire is intermittently connected to the vicinity of the groove on a straight line parallel to the tread circumferential direction. A tire for a motorcycle, characterized in that an auxiliary groove is provided.

(2) The motorcycle tire according to (1), wherein the sub-groove is disposed on a side facing the main groove across the equator of the tire.

  According to the present invention, in the tread having a groove extending in a wavy shape through a bend at the center of the tread, the sub-groove that carries out heat dissipation during traveling in cooperation with the wavy groove is appropriately disposed. Durability can be improved. Therefore, even when the thickness of the tread rubber is increased in order to suppress the occurrence of shimmy, excellent high-speed durability can be maintained.

It is a figure which shows the tread pattern of the tire according to this invention. It is a figure which shows another tread pattern of the tire according to this invention. It is a figure which shows the tread pattern of a comparative tire.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an unfolded tread surface of a motorcycle tire according to the present invention.
The tread 1 has a main groove 2 extending in a wave shape along the equator O of the tire at the center thereof. The main groove 2 has a wave shape that swings with the equator O of the tire as the origin, a trapezoidal wave shape in the illustrated example, and may be a sine wave or a rectangular wave shape. Further, intermediate grooves 3 that extend from the vicinity of the main groove 2 toward the tread end E in an inclined manner with respect to the equator O of the tire are arranged at intervals in the circumferential direction on both sides of the main groove 2. The intermediate groove 3 is composed of a main body 3a extending obliquely from the main groove 2 side with respect to the tire equator O and a bent portion 3b extending in the opposite direction to the main body 3a. Thus, a slight difference is provided in the main body 3a.

  That is, by providing the main groove 2 that extends in a wave shape along the equator O of the tire in the center of the tread, the drainage performance during straight traveling is ensured, as well as the contact pressure increases during high-speed straight traveling, The heat dissipation of the tread center part can be achieved. On the other hand, the intermediate groove 3 is mainly responsible for drainage at the tread shoulder portion during turning.

  As described above, the ground pressure at the center of the tread increases during straight traveling and the temperature rises.Therefore, it is necessary to dissipate heat by providing a main groove in the center of the tread. Since the tread central portion is further heated, it is necessary to further dissipate heat in the tread central portion.

  Therefore, in the present invention, by providing the sub-groove 4 extending intermittently in the tread circumferential direction in the vicinity of the main groove 2, the heat dissipation effect at the tread central portion is further enhanced. That is, in the example shown in FIG. 1, the auxiliary groove 4 is provided on the tire equator O, which is the amplitude center of the main groove 2, and is cut at the portion of the main groove 2 across the equator O and intermittent in the circumferential direction. The sub-groove 4 does not have to define the length, depth, and opening width in particular, and it is sufficient that a concave portion that promotes heat dissipation is formed.

  By the way, the length, depth, and opening width of the sub-groove 4 are as follows: Length: length that fits within one wavelength of the waveform without communicating with the main groove 2, depth: 50 to 100% of the depth of the main groove 2 And opening width: 20 to 50% of the opening width of the main groove 2 is preferable from the viewpoint of heat dissipation.

  Here, when there is no groove in the tread central part, the temperature distribution in the tread central part during straight running is the highest temperature part on the equator O of the tire, but the main groove 2 is provided in the tread central part. It was newly found that the maximum temperature portion moves to a position deviating from the equator O of the tire. Therefore, as shown in FIG. 2, it is effective to further improve the heat dissipation by arranging the auxiliary groove 4 on the side facing the main groove 2 across the equator O of the tire, as shown in FIG. Such a proper arrangement of the sub-grooves 4 can further enhance the heat dissipation effect and further improve the high-speed durability.

In arranging the sub-groove 4 on the side facing the main groove 2 across the equator O of the tire, the minimum distance a from the equator O to the main groove 2 of the tire and the distance from the equator O to the sub-groove 4 are also the same. The minimum distance b is the following formula: a ≧ b ≧ 0
Is preferably satisfied. This is because, if b <a, the sub-groove 4 is disposed at a position away from the maximum temperature range, and there is a concern that the above-described effect is reduced. On the other hand, when b <0, as in the case of b <a, the sub-groove 4 is disposed at a position away from the maximum temperature range, and there is a concern that the above-described effect is reduced.

A tire for a motorcycle having a tread pattern shown in FIG. 1 or 2 and having a size of 130 / 90B16M / C67H was manufactured.
The tire has a fragrance in which the outer side in the radial direction of the crown portion of the three carcass plies made of polyester cord arranged at an inclination angle of 34 ° with respect to the tire equator is arranged at an inclination angle of 22 ° with respect to the tire equator. It is reinforced by a breaker consisting of two plies of a group polyamide fiber cord.

  The main groove 2 formed in the tread has an opening width: 4.8 mm, a depth: 4.3 mm, a wavelength: 96 mm, an amplitude: 19 mm, a distance a from the tire equator: 4.7 mm, and the auxiliary groove 4 has an opening width: 1.5 mm. The depth is 3.8 mm, and the other groove conditions are the same in FIGS. 1 and 2. However, the tread pattern shown in FIG. 2 differs from the tread pattern shown in FIG. 1 in that the sub-groove 4 is arranged at a distance b from the tire equator of 3 mm.

For comparison, a two-wheeled vehicle tire (comparative example) having a tread pattern shown in FIG.
Each prototype tire thus obtained was incorporated into an applicable rim, adjusted to an internal pressure of 350 kPa, and subjected to a high-speed durability drum test under a load condition of 1.96 kN. In the high-speed endurance drum test, the running speed was increased until the tire broke, and the evaluation was made based on the speed at which the broke occurred. The evaluation results are shown in Table 1 as an index when the breaking speed of the comparative example is 100.

  As shown in Table 1, the provision of the secondary groove improves the high-speed durability by 10% or more. In particular, when the secondary groove is separated from the tire equator to the side opposite to the main groove, a 15% improvement allowance is obtained. be able to.

DESCRIPTION OF SYMBOLS 1 Tread 2 Main groove 3 Intermediate groove 3a Body part 3b Bending part 4 Sub groove

Claims (2)

In a motorcycle tire having a groove extending in a wave shape along the equator of the tire on a tread surface of the tire,
A motorcycle tire characterized in that an auxiliary groove extending intermittently on a straight line parallel to the tread circumferential direction is provided in the vicinity of the groove.   The motorcycle tire according to claim 1, wherein the sub-groove is disposed on a side facing the groove with the equator of the tire interposed therebetween.

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