JPS60240506A - Tire for motor-cycle - Google Patents

Abstract

PURPOSE:To enhance the high-speed durability of the captioned tire by placing the predetermined cushion rubber at the both ends of a breaker consisting of a sheet of pry having the predetermined cord angle and placing the middle belt layer having the predetermined cord angle on the outer side of the middle line of the rubber thickness together with placing sidebelt layers at the both ends of the middlebelt layer. CONSTITUTION:A breaker 7 consisting of a pry having an angle of 5 deg.-45 deg. to the circumferential direction of a tire is formed in the same width as the tread width W of the tire. The width of the upper side pry 7a is made smaller than that of the lower side pry 7b. Cusion rubber 70, which is 40 deg.-75 deg. in JIS hardness and the thickness of which reduces toward the both ends, is arranged between the both ends of the both prys 7a and 7b in order to absorb or alleviate the strain occurring at the end of the pry. In addition, a middle belt layer 11 having the cord angle of 10 deg.-40 deg. is placed at the outside of the breaker 7 along the middle line of the rubber thickness, while side belt layers 12a each having the cord angle of 0 deg.-10 deg. are placed on the both sides of the middle belt layer 11, being neighbored on the upper side pry 7a. With this constitution, durability, road gripping performance, and running performance of the tire at the time of high speed running can be enhanced.

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.

Recently, as roads have become more paved, vehicles have become faster, and tires for motorcycles are also required to have better performance during high-speed driving.

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. When the tire is tilted significantly against the road surface (considering a large camber angle), a force (camber thrust) is generated in the tire horizontally to the road surface in the direction of the camber angle, counteracting the centrifugal force acting on the vehicle body, resulting in stable driving. The property of maintaining the Therefore, motorcycle tires use a carcass with the above-mentioned cross-ply structure to increase lateral rigidity and maintain camber thrust, and radial structures with poor lateral rigidity have rarely been adopted from the above point of view. However, tires with a cross-ply structure have disadvantages in terms of wear resistance and the generation of lateral vibration of the vehicle body (WBAVB phenomenon) due to the tire's cornering power and lateral rigidity when driving at high speeds. Countermeasures have been taken to increase tire rigidity, such as lowering the angle relative to the circumferential direction and increasing the number of carcass plies, but as long as a cross-ply structure is adopted, the defects caused by that structure cannot be completely eliminated. .

Recently, there have been proposals that adopt a radial structure and improve the beat structure.
503, Japanese Patent Application Publication No. 58-185304, Japanese Patent Application Publication No. 58-16
0806, Utility Model 58-160805, and Utility Model 58
There is -160807.

However, with this type of radial structure tire, there is a problem in that the centrifugal force that accompanies high-speed running causes a lifting effect on both ends of the breaker, resulting in peeling damage between the carcass or between the breaker and plies. . Therefore, the inventor conducted various studies regarding the carcass reinforcing layer and breaker for the radial structure, as well as the packaging, arrangement, and materials.As a result, the inventor improved the camber thrust to the same level as tires outside the cross-brie structure, and also improved the camber thrust of the radial tire. The present invention has been achieved by realizing the advantages of wear resistance, road surface holding performance, and high mountain running performance, and also solving the problem of the brake peeling off at one end of the breaker.

The present invention includes a tread portion, a sidewall portion extending inward in the radial direction b from both ends of the tread portion, the nightwall portion, and a bead portion located at the radially inner end portion of the sidewall portion, A toroidal carcass consisting of a cord extending approximately parallel to the radial direction of the tire, with both ends folded back around the bead core, and this carcass D is arranged radially outward, and the cord angle is in the tire circumferential direction. A breaker consisting of at least one ply with the fiber cord aligned at an angle of 5" to 45°, and a breaker arranged between the plies at both ends of the breaker and centered around the upper ply end. Cushion rubber with a JIS hardness of 40' to 75° whose thickness gradually decreases in both sides,
A central belt layer disposed outside the breaker at the center of the tread and having cord angles arranged at 10° to 45° with respect to the tire circumferential direction, and a central belt layer on both sides of the central belt layer or at both ends thereof. This is a motorcycle tire characterized by comprising a side belt layer which is arranged to overlap with the tire part and whose cord angle is arranged at 0° to 10° with respect to the tire circumferential direction.

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

FIG. 1 shows the right half of a sectional view of the motorcycle tire of the present invention. In the figure, the tire (1) of the present invention includes a tread part (2), a sidewall part (3) extending radially inward from both ends of the tread part (2), and a bead located at the radially inner end of the sidewall part. It has part (4). Here, the tread portion (2) extends on the crown of the carcass almost parallel to its outline from the center of the crown toward both ends, and its linear width (Wt) is usually configured with a cross-sectional shape exceeding the maximum width (Ws) of the sidewall portion. , thereby maintaining camber thrust when the tire is tilted.

Next, the carcass (5) of the tire of the present invention is composed of two plies, both ends of which are folded back from the inside to the outside around the bead core (6) and either the bead part (4) or the sidewall part (3). ) terminates in 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,
It is desirable to have a shear that completely covers the inner folded end and relieves stress concentration at the end. 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. It is desirable to set the height in the range of 55-70% and 60-12% of the height H). The cords of the carcass are then arranged parallel or substantially parallel to the radial direction of the tire. Here, "substantially parallel" means that the cords are inclined in the radial direction at an angle of less than 10@, and if a configuration exceeding 106 is adopted, the excellent high-speed running characteristics characteristic of radial tires cannot be obtained.

Further, the fibers used for the carcass cord are organic fibers such as nylon, polyester, rayon, 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 5° to 45° with respect to the tire circumferential direction, preferably 20°.
placed at an angle of ~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. The breaker (7) is usually composed of two plies, but the width of one ply is the same as the tread width (W).
t) with substantially the same width. The fiber cord used for the breaker is an aromatic polyamide fiber cord with a strength of 7 g/d or more and an initial modulus of 200 g/d or more, and a 300% modulus of 120 to 240 kg.
/cnt buried parallel to the rubber is preferred;
In addition, organic fiber cords such as nylon, polyester, and rayon, or inorganic fiber cords such as steel cords can be used. The upper ply 7a disposed on the side adjacent to the tread portion of the breaker is formed to have a narrower width than the lower ply (7b) disposed on the side adjacent to the carcass. Lower ply (7
Cushion rubber (10) is arranged between both ends of b).

Here, the cushion rubber (10) has a JIS hardness of 40° to 75°, whose thickness gradually decreases in both directions centering on the upper ply end.
Preferably, the rubber is 48° to 58" and has a high resilience to effectively absorb and alleviate distortion at the ends of the ply. The lower end of the cushion rubber (10) is the end of the lower ply (7b). Although it terminates nearby, it can also be placed so as to cover the end of the lower ply (7b).In addition, when the breaker is composed of one ply, this cushion rubber (10) is connected to the breaker as described below. It can also be placed between the side plies.

Next, in the present invention, a central belt layer (11) is arranged at the center of the tread outside the breaker. This central belt layer (11) is configured to be narrower than the width of the breaker (7), preferably 50 to 50 times the width of the breaker (7).
It is in the range of 80%.

The cords of this central belt layer are arranged at an angle of 10° to 40″ with respect to the tire circumferential direction.

Also, side belt layers (12) are arranged adjacent to the upper ply (7a) of the breaker on both sides of the central belt layer (11). The outer end of this side belt layer (12) is located within a range of ±10 mm from the position of the end (E) of the lower ply (7b) of the breaker. The cords of the side belt layer (12) are arranged at an angle of 0° to 10° with respect to the tire circumferential direction, and the material thereof can be substantially the same as the cords of the central belt layer. Here, a central belt layer (11) and a side belt layer (1
2) is a ply in which organic fiber cords are embedded in parallel in rubber, and the embedded density is 30 to 60 cords 15c.
m, preferably 40 to 50 plies of 75 cm, and these plies can be made into one layer or multiple layers.

Generally, in a radial tire, the breaker cord and the carcass cord intersect at a large angle, so shear strain is large at the interface between the two, especially near both ends of the breaker. Moreover, in combination with the lifting effect at both ends of the breaker caused by centrifugal force as the tire rotates at high speed, it has the function of preventing peeling between the ply of the carcass and the breaker, as well as peeling of the rubber at both ends of the breaker. In particular, in the present invention, the cord angle of the central belt layer disposed at the center of the tread is increased to suppress an unreasonable increase in rigidity in this region, and the cord angle of the side belt layer disposed at a portion of the shoulder is increased. By making the breaker smaller and increasing the rigidity of this region, it not only improves handling stability but also effectively prevents the rubber from peeling off at one end of the breaker.

Furthermore, in the present invention, a bead core (6) is provided in the carcass and its folded end, or in a portion surrounded by the cord reinforcing layer.
By arranging a bead apex (9) made of hard rubber that extends from the bead portion to the sidewall direction with a gradually decreasing thickness, it is possible to strengthen the lateral rigidity from the bead portion to the sidewall direction. This bead apex (
9) is arranged such that its upper end extends from near the maximum width of the sidewall to between one end of the breaker, preferably partially overlaps both ends of the breaker, and has a JIS hardness of 65.
The range is from 95° to 95°.

Next, FIG. 2 shows another embodiment of the tire of the present invention. In the figure, outside the upper ply (7a) of the breaker is a central belt layer (13) of substantially the same width as the lower ply (7b).
is arranged, and two side belt layers (14) and (15) are arranged at both ends of this central belt layer (13). Furthermore, on the outside of the carcass in the radial direction,
A reinforcing layer (8) of fiber cords is arranged from one bead portion to the other bead portion, and both ends thereof are terminated without being folded back around the bead core.

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, the longitudinal springs of the sidewall section are It is necessary to increase the lateral spring constant without increasing the constant, so the cord angle should be set at 45° to 85°, preferably 60° to the circumferential direction.
Arranged at 80°. 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. The fiber cords used in the reinforcing layer can include organic fiber cords such as nylon, polyester, rayon, and aromatic polyamide, as well as steel cords. When the bead apex (9) is arranged, the reinforcing layer may be interposed between the outside of the bead apex (9) and the folded ends (5a) (5b); 9) The structure interposed between the inside of the carcass ply and the carcass ply is similarly adopted.

In the present invention, various changes can be made to the arrangement of the center belt layer and the side belt layers of the breaker 1, and the schematic structure thereof is shown in FIGS. 3(A) to 3(F). In the figure, B indicates the center belt layer of the breaker 1C, and D indicates the side belt layer.

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 layer are arranged in a specific structure, which strengthens the lateral rigidity, which is a drawback peculiar to radial structure tires, and increases camber thrust, enabling stable cornering. The phenomenon of cracking can also be effectively prevented. Moreover, when arranging the cushion rubber at the end of the tread, the central belt layer and side belt layer were arranged on the outside of the breaker, and the angles of these cords were set within a specific range. It is also possible to adjust the stiffness of a portion of the shoulder, thereby preventing ply separation at both ends of the breaker while maintaining steering stability.

EXAMPLE As an example of the present invention, rear tires with tire sizes of 130/80-18 were manufactured as trial tires having the structures shown in FIGS. 1 and 2, and partially modified versions of these structures. 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 1, 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 10km/h, 10km/h.
The speed was increased at minute intervals 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 durability is 150% of the JATMA specified maximum load.
(405 kg) and the internal pressure is the maximum value specified by JATMA (2,9
It was evaluated by running on a 60-inch drum at a speed of 65 km/h and 0 kg/clTl).

In addition, the performance evaluation of actual vehicle driving below is based on VF as the vehicle type.
The measurements were taken using a 750F with 120/80V16 cross-ply tires mounted on the front wheels and tires listed in Table 1 on the rear wheels.

[Brief explanation of drawings]

Figures 1 and 2 are the right half of the cross-sectional view of the motorcycle tire of the present invention, and Figures 3 (A) to 3 (F) are the center belt layer and side belt layer of the breaker 1 of the present invention. The schematic structure of the arrangement state is shown. 1. Tires 7. Breaker 2, tread part 8. Reinforcement layer 3, side wall part 9. bead apex 4
, bead part 10. Cushion rubber 5, carcass
11. Central belt layer 6, bead core 12.13.14. Side belt layer patent applicant Sumitomo Rubber Industries, Ltd. Representative Patent attorney Yoshihira Nakamura Figure 1 Figure 2 Figure 3 (A) Figure 3 (a) 0] Figure 3 (C) Figure 3 (S) ) Figure 3 (J,) Figure 3 (8)

Claims (5)

[Claims] (1) It has a tread part, a sidewall part extending radially inward from both ends of the tread part, and a bead part located at the radially inner end of the sidewall part, and is approximately A toroidal carcass consisting of cords extending in parallel, both ends of which are folded back around the bead core, and a toroidal carcass arranged radially outward of this carcass, with a cord angle of 5'' to the circumferential direction of the tire.
A breaker consisting of at least one ply in which fiber cords are aligned in a range of 45 degrees, and a breaker is disposed between the breaker at both ends of the breaker, and has a thickness extending in both directions centering on the upper ply end. JIS hardness gradually decreasing from 40° to 75°
a cushion rubber, a central belt layer disposed outside the breaker at the center of the tread and having cord angles of 10° to 45° with respect to the tire circumferential direction, and both sides or both ends of the central belt layer. The cord is placed overlapping both ends of the tire, and the cord angle is between 0'' and 1'' with respect to the tire circumferential direction.
A motorcycle tire characterized by comprising a side belt layer arranged in a 06 arrangement. (2) The tire according to claim 1, wherein the breaker is made of an aromatic polyamide fiber cord. (3) It has a tread part, a sidewall part extending radially inward from both ends of the tread part, and a bead part located at the radially inner end of the sidewall part, and is approximately A toroidal carcass consisting of cords extending in parallel, both ends of which are folded back around the bead core, and a toroidal carcass that is placed radially outside of this carcass, extending from one bead to the other, and both ends of which are folded back around the bead core. The cord angle is 45° to the circumferential direction of the tire.
A fiber cord reinforcing layer arranged at 85@, and at least one sheet of fiber cord arranged radially outside of the reinforcing layer and having fiber cords arranged at a cord angle in a range of 5@ to 45 degrees with respect to the tire circumferential direction. A breaker made of a ply, and a cushion rubber having a JIS hardness of 40° to 75°, which is disposed between the plies at both ends of the breaker, and whose thickness gradually decreases in both directions centering on the upper ply end. A central belt layer disposed outside the breaker at the center of the tread and having cord angles of 10' to 456 with respect to the tire circumferential direction, and a central belt layer on both sides of the central belt layer or at both ends thereof 1. A motorcycle tire comprising a side belt layer which is arranged to overlap with the belt layer and whose cord angle is arranged at 0° to 10° with respect to the tire circumferential direction. (4) The cord angle of the reinforcing layer is 60° to 8 in the tire circumferential direction.
The tire according to claim 3, which is in the range of 0°. (5) The cord angle of the reinforcing layer is 60° to 8 in the tire circumferential direction.
The tire according to claim 3, which is in the range of 0°.