JPS60244603A - Motorcycle tire - Google Patents

Abstract

PURPOSE:To enhance lateral and circumferential rigidity of a tire and thereby improve wear resistance, by providing between a reinforcing layer and a tread portion a belt layer including aramid fiber cords arranged circumferentially at a relatively shallow angle. CONSTITUTION:A tire T includes a carcass formed by three plies 2-4 turned about bead cores from inside to outside and terminated at bead portions or side wall portions. Each cord of the plies is arranged at angles of 18-34 deg. relative to a circumferential center plane C of the tire in such a manner as to intersect between the adjacent plies. A reinforcing layer 5 including aramid fiber cords is arranged adjacently outside of the carcass in such a manner as to extend from one of the bead portions to the other without being turned about the bead cores 1. A belt layer 7 is provided between the reinforcing layer 5 and the tread portion 6, and includes cords arranged at a relatively shallow angle.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motorcycle tire having excellent high-speed durability, high-speed stability, wear resistance, etc.

Motorcycle tires have a structure with high lateral rigidity, that is, cross-ply structure tires, which are widely used because of the need to maintain running stability during cornering. It is being On the other hand, in recent years, as highway networks have become more developed and vehicle bodies have improved in performance, motorcycle tires have come to be required to have high-speed running characteristics. When tires run at high speeds, a so-called lifting phenomenon occurs in which the tire crown protrudes due to the centrifugal force that accompanies high speed rotation.In order to suppress this phenomenon, a belt layer consisting of cords at a relatively shallow angle in the circumferential direction of the tire is installed in the tire crown. is placed. Here, aramid fiber cords with high elastic modulus are usually used for the cords of the belt layer, but nylon fibers have been generally used for carcass cords.

The difference in elastic modulus from that of the cord is too large, resulting in a difference in rigidity due to the structure of the tire. In other words, the tread part reinforced with the aramid fiber cord belt layer has extremely high rigidity, whereas the part between the side part and the bead part, which is reinforced with the nylon fiber cord carcass, is relatively flexible. This results in distortion in the carcass and adjacent portions of both ends of the belt layer, resulting in the problem of peeling between the plies of the belt layer.

The present invention adjusts the rigidity balance of each part of the tire to solve the problems of poor handling stability and inter-ply separation, and also improves wear resistance and high-speed durability, which are the advantages of using aramid fiber cord in the belt layer. This paper proposes a motorcycle tire that can more effectively achieve the desired performance.

The present invention consists of at least two plies in which organic fiber cords are arranged at an angle of 18° to 34° with respect to the circumferential center plane of the tire, and the plies intersect with each other, and the two ends thereof are arranged in a pair. The carcass is folded back with a bead core,
A reinforcing layer of aramid fiber cords adjacent to the outside of the carcass and extending from one bead part to the other bead part and terminating without being folded back at the bead core, and between the outside of this reinforcing layer and the trend part. This is a motorcycle tire consisting of a heald layer in which aramid fiber cords are arranged at a relatively shallow angle in the circumferential direction of the tire.

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

In the figure, the tire T has a carcass made up of three plies 2.3.4 which are folded around a bead core from the inside to the outside and whose ends are terminated at the bead or sidewall. The cords of the plies are arranged at an angle of 18° to 34° with respect to the circumferential center plane C of the tire, and have a cross-ply structure such that the cords intersect between adjacent plies.

Conventionally, in a cross-ply structure, the angle of the ply cord of the carcass is 20° to 4° with respect to the center plane C in the tire circumferential direction.
Although they are arranged in a range of 0°, in the present invention, this angle is made small to increase lateral rigidity and improve steering stability at high speeds. It is preferable to use nylon as the material for the carcass ply cord, but rayon and polyester can also be used. These fiber cords have relatively high deniers, for example, 1,500 to 4,000 deniers. Naori-Kasu's ply has a structure that folds around the bead core from the inside to the outside.
It is also possible to use it in combination with a structure in which the bead core is folded back from the outside to the inside.

In the present invention, a reinforcing aramid fiber cord M5 that terminates without being folded back at the bead core 1 is arranged adjacent to the outside of the carcass and extending from one end portion to the other end portion. This reinforcing layer is usually composed of a single ply, and has the effect of increasing the rigidity between the bead and sidewall, reducing cornering power, and suppressing weave mode (high-speed vibration) to improve handling stability. have Therefore, the cord angle of the reinforcing layer is C
The cords are arranged so as to intersect in the opposite direction to the cords of adjacent carcass plies at an angle of 15 to 70 degrees, preferably 18 degrees to 34 degrees. The end portion 5a of the reinforcing layer is preferably located near the upper end of the rim flange (t') on the upper side of the bead core 1, and this structure improves fitability with the wheel rim without unnecessarily increasing the rigidity of the bead portion. The distance from the bottom of the bead to the end 5a of the reinforcing layer is usually in the range of 10 to 30 fins.

In the present invention, a belt layer 7 is disposed between the reinforcing layer 5 and the tread portion 6, and the cords of this belt layer are arranged at a relatively shallow angle, for example, 40 degrees, with respect to the center plane in the tire circumferential direction.
The angle is preferably 18° to 34°. The structure in which belt debris is applied suppresses lifting of the tire crown due to centrifugal force during high-speed driving, further improving straight-line driving stability. Here, aramid fiber cords are used for the cords of the belt layer, making the tensile strength in the circumferential direction of the tire even more effective. Further, the width of the belt layer is usually substantially the same as the width of the tread portion.

However, it is also possible to make only the central portion of the crown portion, for example, approximately 50% of the width of the tread portion.

As described above, the present invention provides a tire with a cross-ply structure in which the cord angle is relatively small in the center plane in the tire circumferential direction, and a reinforcing layer and a heald layer of aramid fiber cords are arranged on the tire, thereby improving the lateral rigidity and circumferential direction of the tire. As the rigidity is further improved and the difference in rigidity between the crown section and the sidewall section is reduced, high-speed durability, high-speed stability, wear resistance, etc. are improved. Furthermore, since the present invention has improved lateral rigidity, it has high run-flat performance in the event of a puncture, and the bead fH
To? 1lid width, etc.? 7i1 strength: Since the f-stage is not necessary for survival, it is possible to reduce weight and make the lower punch of the product @butcher. Therefore, the present invention can be suitably employed as a high-power 1FIJ rear wheel tire for stray running, as well as a run-flat tie, a motocross tire, and an endeuro tie.

EXAMPLE The lateral stiffness, longitudinal stiffness, and cornering force of a tire having a tire size of 130/90V-18, which was prototyped with the cross-sectional structure shown in FIG. 1 and the specifications shown in Table 1, was measured. In addition, high-speed driving tests were conducted on a motorcycle equipped with Tire A on the front wheel and Tire B on the rear wheel (Example 1) and a motorcycle equipped with Tire A on the front wheel and Tire C on the rear wheel (Comparative Example 1). Stability and run-flat characteristics were evaluated.

(a) Lateral stiffness, longitudinal stiffness Each tire was filled with the specified internal pressure, and the lateral and longitudinal deflections when lateral force or load was applied were measured. The results are shown in Figures 2 and 3.

Tire B of the present invention has a higher lateral rigidity than Tire C of the comparative example.
It is recognized that both longitudinal rigidities have improved.

(b) Cornering force Figure 4 shows the measurement results of the relationship between the slip angle and cornering force for each tire.

Tire B of the present invention has a small cornering force,
It can be seen that high-speed stability is excellent.

(c) Actual vehicle driving test (high-speed stability, run-flat performance) High-speed stability was measured using the above-mentioned motorcycle at an average speed of 200 km.
The feeling when running at a speed of /h was evaluated using a 10-point scale. In addition, run-flat performance was evaluated by determining whether the vehicle could turn in a circle with a radius of 20 m when the internal pressure was reduced.

The results are shown in Table 2.

Table 2

[Brief explanation of the drawing]

Figure 1 is the left half of the cross-sectional view of the tire of the present invention, Figures 2 and 3 are graphs showing the relationship between lateral deflection and lateral force, and the relationship between longitudinal deflection and lateral force, respectively, and Figure 4 is a graph showing the relationship between slip angle and lateral force. It is a graph showing the relationship with cornering force. 1-bead core, 6-) red part, 2.3.4-carcass ply, 7-belt layer, 5-? i
li stratum corneum. Patent agent Sumitomo Rubber Industries Co., Ltd. Patent attorney Naemura Tobe 1 Riki Meyoko (Ni 9) Pickpocket...

Claims (1)

[Claims] (1) Yes tffl IJk V4F cord consists of at least 2N plies arranged between the circumferential centers of the tire at an angle of 18° to 34°, the plies intersect with each other, and both ends thereof are A carcass folded back by a pair of bead cores, and an aramid fiber cord adjacent to the outside of the carcass, extending from one bead part to the other bead part and terminating without being folded back by the bead cores.
+3! I! A motorcycle tire comprising scrap and a belt Fl in which aramid fiber cords are arranged at a relatively shallow angle in the tire circumferential direction between the outside of the reinforcing layer and the trend part.