JP3490838B2 - Motorcycle tires - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motorcycle tire having improved steering stability.

[0002]

2. Description of the Related Art Regarding the stability of motorcycle tires, firstly, it is possible to drive stably from the medium speed range to the high speed range, secondly, good convergence with respect to disturbance from the road surface, and thirdly. The ride is comfortable.

[0003] In order to achieve these stability,
For example, changing the carcass, the cord material of the belt, the cord angle, increasing the hardness of the tread rubber, and increasing the gauge of the tread rubber. Was considered effective. Regarding the improvement of the carcass, usually, a carcass cord made of a material having the same or very similar physical property values is used for each layer of the plies having a plurality of layers.

[0004]

However, in the conventional improvement, although the stability of the motorcycle tire can be improved to some extent, other performances such as cornering performance and abrasion resistance performance are deteriorated, or There was a problem such as an increase in tire weight. Further, it is difficult to improve the stable running, the convergence of the disturbance, and the riding comfort of the motorcycle from the middle speed range to the high speed range by such an improvement method.

As a technical problem to solve the above problems, the present inventor has conducted intensive studies and, as a result, has focused on a carcass forming a basic skeleton of a tire for a motorcycle.

And, as the cord material of the carcass, materials having greatly different moduli are used, and the carcass is
The inventors have found that the above problem can be solved by forming a two-layer structure composed of a high modulus ply in which high modulus organic fiber cords are arranged and a low modulus ply in which low modulus organic fiber cords are arranged.

As described above, according to the present invention, in a motorcycle tire, stability is improved without impairing other performances such as cornering performance, and in particular, stable running from a medium speed range to a high speed range. , And to improve the disturbance convergence at the same time.

[0008]

The invention according to claim 1 is
A carcass of radial structure which is locked around the bead core of the bead part from the tread part through the sidewall part, and in which the cords are arranged at an angle of 70 to 90 ° with respect to the tire circumferential direction, and a radial direction of the carcass. A motorcycle tire comprising a belt layer arranged outside and inside the tread portion and having cords arranged at an angle of 0 to 30 ° with respect to the tire circumferential direction, wherein the carcass is a high modulus HM organic tire. A two-layer structure is formed by stacking a high modulus ply in which fiber cords are arranged and a low modulus ply in which organic fiber cords of low modulus LM are arranged in the tire radial direction, and has a high modulus H of the organic fiber cords.
Modulus ratio of M and low modulus LM (HM / LM)
Is 3.8 to 5.2, and the carcass
Red high modulus ply and low modulus plastic
By inserting a cushion rubber between the
It and a cord spacing in the tire radial direction is 0.8 to 2.0 mm
It is a motorcycle tire that.

In the invention according to claim 2 , the carcass is characterized in that a low modulus ply is arranged on the tire cavity side.

The invention according to claim 3 is the high modulus
High Young's modulus HY of organic fiber cord of HM and low modular
The ratio of the organic fiber cord of SLM to the low Young's modulus LY (HY
/ LY) is 3.7 to 6.6
A motorcycle tire according to item 1 or 2.

In the present specification, "modulus"
Then, as the stress per 1 denier of cord ( kgf / d)
It is defined .

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. The tire for a motorcycle of the present invention comprises sidewall portions 3 extending inward in the radial direction from both ends of the tread portion 2 and a bead portion 4 continuous to the inside in the radial direction of the sidewall portion 3, the end of the tread portion being provided. The tread width TW, which is the axial distance between the edges E and E, is
Makes the maximum width of the tire.

The motorcycle tire has a carcass 6 that passes from the tread portion 2 through the sidewall portion 3 and is folded back around the bead core 5 of the bead portion 4, and inside the tread portion 2 and radially outward of the carcass 6. And a belt layer 7 that is arranged, in this example, on the outer side in the radial direction of the bead core 5,
A bead apex 8 made of hard rubber extending outward in the tire radial direction is provided between the main body portion 6a of the carcass 6 and the folded-back portion 6b. The bead portion 4 may be provided with a reinforcing member such as a chafer.

As shown in FIG. 2, the carcass 6 has a radial structure composed of plies in which cords are inclined in an angle of 70 to 90 ° with respect to the tire circumferential direction and arranged in topping rubber, and has a high modulus HM. The high modulus ply 6H in which only the organic fiber cords 9 of No. 6 and the low modulus ply 6L in which only the organic fiber cords 10 of low modulus LM are arranged are overlapped in the tire radial direction.
It is composed of layers.

In this example, the carcass 6 has a low modulus ply 6L arranged on the tire cavity side. If the cord angle of the carcass 6 is less than 70 °, the radial structure cannot exhibit excellent wear resistance and high speed.

Further, the carcass 6 increases the difference between the high modulus HM and the low modulus LM of the organic fiber cords 9 and 10, that is, the modulus ratio (H) of both cords.
M / LM) is set in the range of 3.8 to 5.2.

With such a carcass structure, the motorcycle tire has improved stability without impairing cornering characteristics, that is, stable running from the medium speed range to the high speed range, and a disturbance input from the road surface. And can exhibit excellent convergence.

In a motorcycle, if the rigidity of the tire is increased,
While cornering performance is improved, it becomes sensitive to disturbance input from the road surface, and wobble mode vibration generated at the front wheels and weave mode vibration generated at the rear wheels become large, especially at high speeds, and the stability is remarkably improved. descend.

However, in the present invention, the carcass 6 has a two-layer structure consisting of the high modulus ply 6H and the low modulus ply 6L, and the modulus ratio of the cord is specified. It is possible to improve the running stability from the high speed range to the high speed range and the disturbance convergence at the time of high speed running, and to eliminate the above-mentioned mode vibration of the front and rear wheels to obtain good stability.

The modulus ratio (H) of the high modulus HM and the low modulus LM of each of the organic fiber cords 9 and 10 is
When M / LM) is less than 3.8, the cornering performance can be improved but the disturbance convergence cannot be improved, and the stability cannot be expected to be improved. On the other hand, when the modulus ratio (HM / LM) exceeds 5.2, the modulus difference becomes too large and the load is concentrated on the organic fiber cord 9 with high modulus HM, resulting in looseness between the plies of the carcass 6 and durability. However, there is a problem in that From this point of view, the sum of the high modulus HM and the low modulus LM of the organic fiber cord is not limited to this range, but can be, for example, 340 to 365 (kgf / d).

Next, a high modulus H used for the carcass 6
As a combination of the organic fiber cord 9 of M and the organic fiber cord 10 of low modulus LM, for example, from the organic fiber cord group of nylon, rayon, polyester, aramid, etc. In the case of a ply, a preferable number of shots per 5 cm (hereinafter referred to as "ends") can be mentioned. What is consistent with the present invention is the combination of C, D, F in this table,
It is not limited to this example. Table 2 shows general physical property values of each code.

[0022]

[Table 1]

[0023]

[Table 2]

The Young's modulus of the carcass shown in Table 2 is also shown in Table 2.
A preferred embodiment is a combination in which the Young's modulus ratio (HY / LY) of the high Young's modulus HY of 0 and the low Young's modulus LY is 3.7 to 6.6. Here, the Young's modulus is synonymous with the initial elastic modulus (tensile) and is defined as the stress per unit cross-sectional area of the cord (kgf / mm ² ). Although the end of each cord of the carcass can be set variously, it is generally 30 to 55.
It is desirable that the number is about this.

Next, the carcass 6 has the high modulus ply 6H and the low modulus ply 6L of the tread portion 2.
As shown in FIGS. 2 and 3 (A), the sheet-shaped cushion rubber 11 is interposed between the tread portion 2 and the tread portion 2, so that the cord interval t in the tire radial direction is 0.8.
It is desirable to adjust to ~ 2.0 mm. The cushion rubber 11 as described above, in combination with the structure of the carcass 6,
It is preferable in that it can contribute to shock absorption and, in particular, to improvement in riding comfort.

Here, if the cord interval t is less than 0.8 mm, the running stability tends not to be sufficiently improved, and conversely, if it exceeds 2.0 mm, the heat generated during running is large. Therefore, the durability of the carcass tends to be reduced. The JIS A hardness of such cushion rubber is preferably 50 to 90 °.

As shown in FIG. 3B, the case where the topping rubber thickness of the plies is adjusted without separately interposing the cushion rubber between the plies 6H and 6L may be used.
Is illustrated in.

Next, in the belt layer 7, cords are arranged at an angle of 0 to 30 ° with respect to the tire circumferential direction, and as the cords, organic fiber cords such as nylon, rayon, polyester and aramid are used. It is preferable.

In this example, as shown in FIG. 2, the belt layer 7 is composed of a plurality of aramid cords 12 arranged in parallel and embedded in a topping rubber and having a strip-shaped ply 13 having a small width of about 5 to 10 mm. A so-called jointless belt is used in which the cord is spirally wound so as to form substantially 0 ° with respect to the tire circumferential direction. The belt layer 7 has a substantially single-layer structure, for example, the tread width TW.
Of 0.85 to 0.95 times.

Further, a wing rubber 16 is provided at the boundary between the tread rubber 14 forming the tread portion 2 and the sidewall rubber 15 forming the outer surface of the sidewall portion 3, so that the stress at the portion is increased. It is possible to prevent concentration.

As another embodiment, according to the present invention, the high modulus ply 6H of the carcass 6 is arranged on the inner side of the tire, and the belt layer 7 is composed of a plurality of layers of cut plies. Is naturally included.

[0032]

[Example] As a tire for a rear wheel of a motorcycle, a tire (Examples 1 to 11) having a tire size of 160 / 60ZR17 and having the configuration and specifications shown in FIG. Tested
Further, the tires (Comparative Examples 1 to 9) having a structure different from that of the carcass of the present invention were also tested and the performance was compared. The carcass cord arrangement angle is the tire equator C.
To 88 ° with respect to each other so that the plies intersect with each other, and the ends follow the examples of ends shown in Table 2 depending on the cord.

The test conditions are as follows. A) Stability / maneuverability (actual vehicle test) Each sample tire was mounted on a rear wheel of a motorcycle with a displacement of 600 cc (rim size: 17 x MT5.00, internal pressure: 290 Kp).
mounted on a) and 120 / 60ZR1 on the front wheels
6 size radial tires (carcass: 1 layer structure in which rayon cords are inclined at 90 ° to the tire equator C, belt layer: 2 cut ply structure in which aramid cords are crossed at 17 ° to the tire circumferential direction) , Rim size:
17 × MT3.50, internal pressure 250 Kpa) was attached to the test course, and the test course was evaluated. The driver's feeling was evaluated, and Comparative Example 1 was evaluated as an index of 100. In each case, the larger the value, the better.
In addition, "stability" is evaluated by focusing on the goodness and badness of convergence with respect to disturbance during straight traveling and turning during high-speed running and the occurrence of weave. In addition, "maneuverability" was mainly cornering (handling) characteristics, and comprehensive evaluation was made on the degree of leaning, agility, rigidity, and touch feeling.

B) Durability (drum test) Each test tire was mounted on a rim of 17 × MT4.50,
Under the conditions of an internal pressure of 250 Kpa, a speed of 60 km / H and a load of 356 kgf, the drum was run on a drum of a drum tester. The test was stopped at the time when visual damage was observed with the finish distance set to 13,000 km. 10,000 km
If the race is completed, it is generally considered that no market trouble will occur. The test results are shown in Table 3.

[0035]

[Table 3]

As a result of the test, the example is the comparative example 1,
It was confirmed that the stability and maneuverability were superior to those of No. 2. In particular, as shown in Examples 7, 8 and 9, a nylon cord is used as the low modulus cord and an aramid cord is used as the high modulus cord, respectively.
It has also been found that a motorcycle tire having a carcass of the present invention having a modulus ratio of 5.0 to 5.2 is preferable in that stability, maneuverability and durability can be comprehensively improved.

As shown in Examples 3 and 4, it was also found that when the low modulus ply is located on the tire bore side, good results may be obtained in terms of maneuverability. Further, in the carcass of the tread portion, it was also confirmed that when the distance t between the cords exceeds 2.0 mm, looseness occurs between the plies of the carcass and the durability tends to be deteriorated.

[0038]

As described above, the pneumatic tire of the present invention is
It is possible to improve stability at the same time, especially in the middle speed range to the high speed range, without sacrificing cornering performance, etc.

[Brief description of drawings]

FIG. 1 is a meridian cross-sectional view of a tire showing an embodiment of the present invention.

FIG. 2 is a development view of a carcass and a belt layer showing an embodiment of the present invention.

3A and 3B are cross-sectional views of a tread portion of a carcass.

[Explanation of symbols]

2 tread section 3 Side wall part 4 bead part 5 bead core 6 carcass 6H high modulus ply 6L low modulus ply 7 Belt layer 9 High modulus organic fiber cord 10 Low modulus organic fiber cord

Claims (3)

(57) [Claims] 1. A carcass of a radial structure, which is locked around a bead core of a bead part from a tread part through a sidewall part, and in which cords are arranged at an angle of 70 to 90 ° with respect to a tire circumferential direction, A motorcycle tire comprising a belt layer arranged radially outside and inside the tread portion of the carcass, and comprising a belt layer in which cords are arranged at an angle of 0 to 30 ° with respect to the tire circumferential direction, wherein the carcass comprises: A high modulus ply in which organic fiber cords of high modulus HM are arranged and a low modulus ply in which organic fiber cords of low modulus LM are arranged in a tire radial direction are stacked to form a two-layer structure. The modulus ratio (HM / LM) of the modulus HM and the low modulus LM is 3.8 to
As well as a 5.2, the carcass, the high modulus plies of the tread portion
Cushion rubber is interposed between the low modulus ply and
The cord spacing in the radial direction of the tire by 0.8
Tire for a motorcycle to be as ~2.0 mm. 2. The tire for a motorcycle according to claim 1 , wherein the carcass is provided with a low modulus ply on the tire bore side. 3. The high modulus HM organic fiber cord
Organic fiber cord with high Young's modulus HY and low modulus LM
Of low Young's modulus LY (HY / LY) of 3.7 to 6.
6. The automatic machine according to claim 1 or 2, characterized in that
Wheel tires .