JPS6157405A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To obtain a pneumatic tire having the radical structure with lateral rigidity and small deflection by setting the cord angle of a section folded from the bead section of a carcass ply below a specific angle for the circumferential direction. CONSTITUTION:A tire 1 has a thread section 2, side wall section 3 that is extended toward the inside in the radial direction from both ends, and bead section 4 positioned at the inside end in the radial direction. In addition, the carcass ply 5 is folded from the inside to the outside around a bead core 6, wound around the side section 3 and terminated. In this case, the cord angle theta of the winding up sections 5a that are wound continuously in the cord 7 of the carcass ply 5 is set to 60 deg. or less for the circumferential direction of the tire and desirably to 35-30 deg.. In addition, for two or more carcass plies 5, the winding up sections 5a are tilted separately in the reverse direction alternately at an angle of less than 60 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a pneumatic tire with a radial structure.

(Prior art and its problems) In a conventional pneumatic tire with a radial structure, the cord angle of the carcass ply is around 90 degrees, and the cord is folded back through the outer periphery of the bead, and the cord is folded back as shown in Figure 4. The structure is such that the cord is wound up at an angle and the end of the cord is located near the sidewall.

By the way, conventional tires of this type often give a driver a feeling of anxiety because of their low lateral rigidity during driving. In addition, the amount of deflection is greater than that of tires with a bias structure of the same size, and they must be used at high air pressure.
# There were problems with durability and safety.

(Object of the Invention) An object of the present invention is to improve the problems of conventional tires with a radial structure and to provide a pneumatic tire with a radial structure that has high lateral rigidity and a small amount of deflection.

(Structure of the Invention) The pneumatic tire according to the present invention has a diameter of about 90 mm in the circumferential direction.
In a pneumatic tire having a radial structure and having one or more carcass plies that are folded back and rolled up at the bead, the cord angle of the part of the carcass ply that is folded back from the bead is in the circumferential direction. It is characterized in that the angle is 60 degrees or less.

(Embodiment) FIG. 1 is a cross-sectional view of an example of a pneumatic tire according to the present invention, and this tire includes a tread portion 2 and sidewall portions 3 extending radially inward from both ends of the tread portion 2.
and a bead portion 4 located at the radially inner end of the sidewall portion.

The carcass of this tire l is composed of one or more plies, and the carcass ply 5 has a bead core 6.
It is folded back from the inside to the outside around the , and is rolled up to the side wall part 3 and terminates. This winding part 5a
The height Hl is preferably 275 or more of the tire height Ha.

The carcass ply 5 may have a structure in which it is folded around the bead core 6 from the outside to the inside, or may be combined with a structure in which it is folded back from the inside to the outside.

As the material of the carcass ply 5, fibers such as nylon, polyester, rayon, or aromatic polyamide are used. The angle of this cord 7 is about 90 degrees with respect to the circumferential direction of the tire in a portion other than the winding portion 5a, preferably 82 to 98 degrees. Further, the cord angle θ of the continuously wound winding portion 5a is 60 degrees or less, preferably 35 to 50 degrees with respect to the circumferential direction of the tire, as shown in FIG. If this angle is too large than 90 degrees, the improvement in lateral rigidity will not be sufficient, as shown in Figure 2.
The case where the number of carcass plies 5 is one is shown, but if there are two or more carcass plies 5, the winding parts are alternately inclined in opposite directions at an angle of 60 degrees or less as shown in Fig. 3. 9 in FIG. 1 is a bead apex made of hard rubber that extends from the bead core 6 in the direction of the sidewall with a gradually decreasing thickness. Lateral rigidity can be strengthened. This bead apex 9 preferably has a JIS hardness of 65 to 8o.

Since this pneumatic tire l has a radial structure, it has the advantages of a radial tire, such as high-speed running performance. The winding portion 5 of the carcass ply 5 has a cord angle of about 90 degrees with respect to the circumferential direction of the tire.
a is inclined so that the cord angle is less than 60 degrees with respect to the circumferential direction of the tire, so interlaminar shear strain occurs at the winding part of the carcass ply, greatly improving sidewall rigidity. There is.

When a tire deforms, the amount of deflection is determined by air pressure, tread rigidity, sidewall rigidity, etc. In a tire with a radial structure, the sidewall rigidity of the carcass, which has a cord angle of about 90 degrees, is mainly achieved by the thickness including the rubber layer. On the other hand, in a bias structure tire, in addition to the above-mentioned thickness, the sidewall rigidity increases due to the shearing force due to the so-called pantograph effect, and the resistance against lateral force is greater than that of a radial structure tire. The low lateral rigidity, which is a drawback of radial structure tires, is compensated for by generating interlaminar shear strain in the carcass winding section, which increases the lateral rigidity of the tire and reduces the amount of deflection. be.

(Effects of the Invention) As explained above, in the pneumatic tire according to the present invention, the cord angle of the winding part of the carcass is inclined to 60 degrees or less with respect to the circumferential direction in a tire with a radial structure, so that the lateral rigidity is increased. However, driving stability has been improved, and tire durability has been improved by reducing the amount of tire deflection. Additionally, since the air pressure in the tires can be lowered, it is also advantageous in terms of safety.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of one example of a pneumatic tire according to the present invention, Figs. 2 and 3 are explanatory views of essential parts of different embodiments, and Fig. 4 is a cross-sectional view of a conventional pneumatic tire of the same type. FIG. 3 is an explanatory diagram of main parts. l... Tire, 2... Tread part, 3... Sidewall part, 4... Bead part, 5... Carcass ply, 5a... Winding part, 6... Bead core, 7...・
·code.

Claims (1)

[Claims] (1) In a pneumatic tire with a radial structure having one or more carcass plies that have a cord angle of about 90 degrees with respect to (1) and are folded back and rolled up at the bead part, the carcass ply is folded back from the bead part of the carcass ply and rolled up. A pneumatic tire characterized in that a cord angle at a portion where the cord is bent is 60 degrees or less with respect to the circumferential direction.