JPS6038209A - Tire for motorcycle - Google Patents

Abstract

PURPOSE:To improve lateral rigidity of the captioned tire while keeping wear resistance, road keeping property, and a highspeed running property by properly selecting structures, arrangements and materials of a carcass reinforcement layer and a braker, in a radial structure of a motorcycle tire. CONSTITUTION:A tire 1 comprises a tread part 2, a side wall part 3 radially extending from both ends of said tread part toward the inside thereof, and a bead part 4 located at the radially inner end part of the tire. Then, the carcass 5 is formed by two plies, and both ends thereof are folded back around a bead core 6 from the inside to the outside of the tire. The cord of the carcass 5 is arranged in parallel to the radial direction of the tire 1. In addition, a braker is arranged with a low cord angle with respect to the tire peripheral direction in the radially outward direction of the carcass 5. Further, bands 10, 11 having the cords arranged in parallel to the tire peripheral direction are provided at the central portion and both ends of the braker outside it.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motorcycle tire, and particularly to a radial motorcycle tire that has excellent durability during high-speed running.

In recent years, as roads have become more paved, vehicles have become faster, and tires for motorcycles are also required to have better performance characteristics when running at high speeds.

Generally, motorcycles have a cross-ply structure in the carcass, that is, the cord angle of the carcass ply is approximately 30° with respect to the circumferential direction.
An arrangement that is angled at an angle of ˜60° and crosses each other between the plies is widely used. This is due to the fact that motorcycle tires are fundamentally different from tires for passenger cars and other four-wheeled vehicles in terms of their dynamic function, especially when turning. (3) (gives a large camber angle), and at that time, the tire is subjected to a force (camber) horizontally to the road surface in the direction giving the camber angle.
It is required to maintain stable running by resisting the centrifugal force that occurs on the vehicle body (thrust). Therefore, motorcycle tires use carcass with the above-mentioned cross-ply structure to increase lateral rigidity and maintain the camber thrust, and radial structures with poor lateral rigidity are rarely adopted from the viewpoint of do not have. However, when tires with a cross-ply structure are driven at high speeds, the lateral vibrations (W) of the vehicle body caused by the cornering power and lateral rigidity of the tires.
EΔVE phenomenon) and wear resistance are at a low point, so countermeasures have been taken to increase tire rigidity, such as lowering the cord angle of the carcass relative to the circumferential direction and increasing the number of carcass plies. However, as long as a cross-ply structure is adopted, the drawbacks caused by that structure cannot be completely eliminated.

Therefore, the present inventor has conducted various studies on the structure, arrangement relationship, and materials of the radial structure of motorcycle tires (4), the reinforcement layer and the breaker, which has rarely been attempted in the past. camber
It was discovered that the thrust could be improved to the same level as a tire with a cross-ply structure, and the advantages of radial tires such as wear resistance, road surface holding properties, and high-speed running performance could be exhibited, and the present invention was achieved.

The present invention has a tread portion, a sidewall portion extending radially inward from both ends of the tread portion, the sidewall portion, and a bead portion located at the radially inner end portion of the sidewall portion. A toroidal carcass consisting of cords that extend almost parallel to the radial direction, with both ends folded back around the bead core, and the cords are placed on the outside of this carcass in the radial direction, with the cord angle being at a shallow angle with respect to the tire circumferential direction. breaker
This motorcycle tire is provided with a band in which cords are arranged substantially parallel to the circumferential direction of the tire at the center and both ends of the outside of the breaker.

(5) In addition to the above structure, the present invention further provides that one bead portion extends to the other bead portion, both ends thereof are terminated without being folded back to the bead core, and the cord angle is 45° with respect to the tire circumferential direction. This is a motorcycle tire in which a fiber cord reinforcing layer is arranged at an angle of ~85°, and the reinforcing layer is arranged.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a partial sectional view of the motorcycle tire of the present invention. In the figure, the tire (1) of the present invention has a tread portion (2
), a sidewall part (3) extending radially inward from both ends thereof, and a bead part (4) located at the radially inner end of the sidewall part. Here, the tread portion (2) extends on the crown of the carcass approximately parallel to its contour from the center of the crown toward both ends,
Its width (W t ) is usually the maximum width of the sidewall part (W
s), thereby maintaining camber thrust when the tire is tilted.

Next, the carcass (5) of the tire of the present invention is made of two plastic pieces (6
), both ends of which are folded back from the inside to the outside around the bead core (6), forming a bead portion (4).
Alternatively, it terminates at the sidewall portion (3). Here, the folded end (5a) located on the outside of the bead portion extends to a higher position than the folded end (5b) located on the inside of the bead portion, completely covers the inner folded end, and reduces the stress at the end. It is desirable to reduce concentration. Furthermore, in order to reinforce the sidewall part, the respective heights of the inner folded part (5b) and the outer folded part (5a) from the bead base part (Hb) (Ha) are the heights of the bead base part at the maximum width position of the sidewall part. 55-65% of height H)
And it is desirable to set it in the range of 70-100%. The cords of the carcass are then arranged parallel or substantially parallel to the radial direction of the tire.

Here, nearly parallel means that the cords are inclined at an angle of less than 10 degrees in the radial direction; if a configuration that exceeds 10 degrees is adopted, the excellent high-speed running characteristics that are characteristic of radial tires will not be obtained. . The fibers used for the cord of the carcass are organic fibers such as nylon, poly(7) ethenopelayon, or aromatic polyamide fibers. In the present invention, one or more carcass plies are used, but the folding structure around the bead core (6) can be folded from the inside to the outside as shown in the figure, or folded from the outside to the inside, or a combination of both. However, the figure shows a structure folded from the inside to the outside as an optimal example.

Next, the breaker (7) in the tire of the present invention is arranged with a width that spans almost the entire width of the tread portion, thereby increasing the effectiveness of the tread portion. Here, the cord of the breaker is at an angle of 10° to 45° with respect to the tire circumferential direction, preferably 20°.
Arranged at an angle of 35° to 35°.

If the cord angle is too small, the tread rigidity will be increased and the impact will be large against stones scattered on the road surface or unevenness of the road surface, which will impede running stability and ride comfort.On the other hand, if the cord angle is too large, the steering stability at high speeds will be affected. inhibit. In addition, the breaker
(7) is usually composed of two briars, but the width of at least one briar is formed to be substantially the same as the tread width (W t ). (8) The fiber cord used for the breaker can be the same as the cord material used for the reinforcing layer, but it is especially an aromatic polyamide fiber cord with a strength of 7 g/d or more and an initial modulus of 2 f.
It is preferable to use a rubber having a 300% modulus of 120 to 240 kg/Crl and embed it in parallel.

Next, in the present invention, both bands (to) (tt) are arranged outside the breaker at the center and at both ends. Band α, which is placed at both ends of the breaker, is caused by the cords of the breaker and the cords of the reinforcing layer intersecting at a large angle, which causes shear strain at the interface between the two, especially near both ends of the reinforcing layer, which causes the plies of the carcass and reinforcing layer to It has the function of preventing delamination from occurring. On the other hand, the band (11) located at the center of the breaker has the function of preventing the protrusion of the center of the tread due to centrifugal force during high-speed running, and suppressing ply peeling due to heat generation. Here, the band was separated into one end and the center of the breaker because the curvature in the circumferential direction of the tire is extremely different between the one end and the center of the breaker due to the unique cross-sectional shape of motorcycles. This is to effectively achieve each of the above functions by arranging the bands.

The band (10) (+1) uses a ply in which organic fiber cords such as nylon, polyester, and rayon are arranged almost parallel to the circumferential direction of the tire and are embedded in rubber, with an embedded density of 30 to 60 cords. / 5cm.

Preferably 40 to 50 pieces/5cm. Furthermore, the band (+0) (0) is wound once or twice in the circumferential direction of the tire, and its width ranges from 10 mm to 60 mm. The width (WN) is 20 to 80 of the arc width (WB>) of the breaker.
% is preferably in the range of 30 to 60%.

Furthermore, in the present invention, by arranging a bead apex (9) made of hard rubber that extends from the bead core in the direction of the sidewall with a gradually decreasing thickness in the area surrounded by the carcass and its folded end, the bead apex (9) extends from the bead portion to the sidewall. It is possible to strengthen the lateral stiffness between directions. The bead apex (9) preferably extends to a position where its upper end overlaps both ends of the breaker, and its JIS hardness is in the range of 65° to 95° (10), preferably 85° to 95°.

Next, in the present invention, a reinforcing layer (8) of fiber cords is disposed on the outside of the carcass in the radial direction, extending from one bead part to the other bead part, and having both ends terminated without being folded back around the bead core. be done. The reinforcing layer (8
) intersects the carcass cord at a certain angle and has the function of reinforcing the sidewall section, but in order to improve cornering characteristics without impeding ride comfort, it is necessary to increase the longitudinal spring constant of the sidewall section. It is necessary to increase the transverse spring constant, and therefore the cord angle needs to be arranged at 45'' to 85°, preferably 60 to 80'' with respect to the circumferential direction. Further, it is desirable that both ends of the reinforcing layer overlap the folded ends (5a) and (5b) of the carcass at the bead portion to alleviate stress concentration in these regions. Note that the fiber cords used for the reinforcing layer include cords of organic fibers such as nylon, polyester pereyon, and aromatic polyamide, as well as steel cords.

Note that the reinforcing layer (8) is made of bead apex (1), which will be described later.
1) When arranging the bead apex (9), it is also possible to adopt a structure in which it is interposed between the outside of the bead apex (9) and the folded ends (5a) and (5b) as shown in the figure, but the bead apex (9) A structure interposed between the inside of the carcass ply and the carcass ply can also be similarly adopted.

However, since the motorcycle tire of the present invention adopts a radial structure in the carcass and has a breaker arranged therein, the inherent characteristics of the radial structure, such as high-speed durability, are improved, that is, the limit speed for generating stunting waves is increased, and rolling resistance is reduced. becomes smaller. In addition, the breaker, carcass folds, and reinforcing layers are arranged in a specific structure, which strengthens lateral rigidity, which is a drawback peculiar to radial tires, and increases camber thrust, allowing stable cornering.
In addition, the so-called buckling phenomenon can be effectively prevented, and since the band is placed at one end of the breaker, ply separation at both ends of the breaker can be prevented.Furthermore, the band (1, 1) is placed in the center of the tread, which improves the tread stability during high-speed running. The phenomenon of protrusion in the center can be suppressed.

(12) Example As an example of the present invention, a tire size of 120 was used for the structure shown in FIG.
/90-18 rear wheel tires were prototyped.

Further, as a comparative example, a cross-ply structure and a conventional radial structure were used. These detailed specifications are shown in Table 1. In Table 7, the camber thrust is shown as a relative value, with the cross-ply structure tire (Comparative Example 2) set as 100.

The higher the number, the better. Also, the generation speed of standing waves is from 150km/h to IOkm/h, 1
The speed was increased at intervals of 0 minutes, and the speed at which standing waves were generated was visually observed.

To determine the speed at which vibrations naturally occur at high speeds, the speed was increased on a high-speed road surface, and the speed at which vibrations occurred was evaluated by feeling.

In addition, the performance evaluation of actual vehicle driving below uses Yamaha XJ1750 as the vehicle model, and the front wheels are 100/90V19.
The cross-ply tires shown in Table 1 were mounted on the rear wheels, respectively, and the measurements were taken (13).

[Brief explanation of the drawing]

1 and 2 are partial cross-sectional views of the motorcycle tire of the present invention. Patent applicant Sumitomo Rubber Industries Co., Ltd. Representative Patent attorney Yoshihira Nakamura (I5) Figure 1

Claims (7)

[Claims] (1) having a tread portion, a sidewall portion extending radially inward from both ends of the tread portion, and a bead portion located at the radially inner end of the sidewall portion;
A toroidal carcass consisting of a cord extending almost parallel to the radial direction of the tire, with both ends folded back around the bead core, and a toroidal carcass arranged on the outside of this carcass in the radial direction, with the cord angle relative to the tire circumferential direction. A breaker arranged at a shallow angle, and a beak at the center and both ends of the outside of the breaker, and a beak at the outer center and at both ends, and a beak in the tire circumferential direction.
A motorcycle tire with a band in which cords are arranged parallel to each other. (2) The tire according to claim 1, wherein the breaker is made of an aromatic ring polyamide fiber cord. (3) The tire according to Claims 1 and 2, wherein the seven raker cords are arranged at an angle of 1) 25° to 45° with respect to the circumferential direction of the tire. (4) The tire according to claim 1, wherein the band is a nylon fiber cord. (5) The tire according to claim 1, wherein the band is wound once or twice in the tire circumferential direction. (6) A tread portion, a sidewall portion extending radially inward from both ends of the tread portion; A toroidal carcass having a bead portion located at the radially inner end of the sidewall portion, consisting of a cord extending substantially parallel to the radial direction of the tire, and having both ends folded back around a peed core, and this carcass. It is arranged on the outside in the radial direction of the tire, and extends from one bead part to the other bead part, and both ends are terminated without being folded back to the peed core, and the cord angle is 45° with respect to the tire circumferential direction.
A fiber cord reinforcing layer arranged at an angle of 85° to 85°, a breaker arranged outside the reinforcing layer with a cord angle at a shallow angle with respect to the tire circumferential direction, and an outer center and both ends of the breaker. A motorcycle tire is equipped with a band in which cords are arranged substantially parallel to the circumferential direction (2) of the tire. (7) The cord angle of the reinforcing layer is 60° to 8 in the tire circumferential direction.
2. The tire according to claim 1, wherein the tire is in the range of 0°.