JPH04300701A - Spare tire - Google Patents

Abstract

PURPOSE:To obtain a light-weight tire without sacrificing the inner pressure retention. CONSTITUTION:A spare tire includes a carcass 6 of cross-ply structure and a belt layer 7 consisting of belt plies using belt cords of organic fiber. The carcass cord is composed of nylon monofilament. An inner liner 9 of thickness 0.5-0.2mm is attached on the inner surface opposed to the tire inner cavity of the carcass.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spare tire whose weight can be reduced without impairing internal pressure retention.

0002

[Conventional technology]

[0003] As vehicles become faster and more sophisticated, spare tires that are used in the event of a puncture are required to have tire performance comparable to regular tires. It is essential to maintain the internal pressure for a long period of time, and there is a growing demand for a lighter spare tire that is always carried in order to improve fuel efficiency.

On the other hand, as a spare tire, there are bias tire types in which the carcass has a cross-ply structure in which the carcass cords intersect, and radial tires in which the carcass is arranged in a radial manner and the hoop effect is enhanced by a belt layer. However, all types of spare tires have conventionally used a multifilament cord made by twisting organic fiber filaments such as nylon as the carcass cord.

[0005]

[Problem to be solved by the invention]

However, with the multifilament cord, the spare tire is, for example, 4.2
Due to the high internal pressure of kgf/cm2, air permeates inside the carcass over time and tends to lower the internal pressure of the tire.In addition, air permeation can cause internal damage such as ply separation. It was found that the tire durability was also reduced. Note that, conventionally, the thickness of the inner liner on the inner surface of a tire is relatively thick, 1 to 2 mm.

[0007] In the present invention, the carcass cord is made of nylon monofilament, and the inner liner has a wall thickness of 0.
The purpose of this invention is to provide a spare tire whose weight can be reduced without impairing various tire performances, based on a thickness of 5 to 0.2 mm.

[0008]

[Means for Solving the Problems] The present invention provides a carcass cord that extends from the tread portion through the sidewall portion and is folded back at the bead core of the bead portion, and the carcass cord is 28 to 38 mm with respect to the tire equator.
A carcass with a cross-ply structure having at least two carcass plies tilted in opposite directions at an angle of 100°, and a belt ply arranged on the outside in the tire radial direction and inside the tread of the carcass and using an organic fiber belt cord. The carcass cord is made of nylon monofilament, and an inner liner with a wall thickness of 0.5 to 0.2 mm is attached to the inner side of the carcass facing toward the tire cavity. .

[0009]

[Function] In the spare tire constructed in this way, the carcass cord is composed of a nylon monofilament cord with low gas permeability, so the thickness of the inner liner attached to the inside of the tire case can be reduced to 0.5 mm to 0.5 mm.
．． Even when formed as thin as 2 mm, there is no decrease in internal pressure and the weight of the tire can be reduced. Furthermore, nylon cord has superior adhesion to rubber compared to aromatic polyamide or steel cord, which reduces peeling during running.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In the figure, a spare tire 1 includes a bead portion 3 through which a bead core 2 passes, a sidewall portion 4 extending outward in the tire radial direction from the bead portion 3, and a tread portion 5 connecting the upper ends of the sidewall portion 4. Further, a toroidal carcass 6 is spanned between the bead parts 3, 3, and a belt layer 7 is arranged on the outside in the tire radial direction and inside the tread part 5.

The carcass 6 is formed of at least two carcass plies 6A and 6B, in this example two carcass plies 6A and 6B, in which carcass cords are arranged at an angle of 28 to 38 degrees with respect to the tire equator, and , 6B carcass cords cross each other. Further, the carcass 6 is provided with a folded part 6b that folds back around the bead core 2 from the inside to the outside on the main body part 6a extending from the tread 5 through the sidewall part 4 to the bead part 3.
The range from the bead portion 3 to the sidewall portion 4 is reinforced by arranging a bead apex 8 that extends outward in the radial direction in a tapered shape.

[0013] A nylon monofilament cord was used as the carcass cord. This is because the nylon monofilament cord was found to have low gas permeability. It is known that this cord has excellent dimensional stability, good adhesion to rubber, and high fatigue resistance.

The nylon monofilament cord used is 1,500 d to 3,500 d, and the number of nylon monofilament cords is approximately 35 to 50 strands/5 cm.

Further, an inner liner 9 made of halogenated butyl rubber is provided on the inner surface of the carcass 6 facing the inner cavity of the tire. This inner liner 9 has a thickness t of 0.5 to
0.2mm, which is half that of conventional tires.

The thickness t of the inner liner 9 refers to the length in the direction perpendicular to the carcass ply 6B in contact with the inner liner 9.

[0017] This makes it possible to reduce the weight. In addition, even when the thickness is halved, the gas permeability of the monofilament cord that makes up the carcass cord is low, reducing internal pressure drop over a long period of time, making unexpected use possible, and preventing air from entering the carcass. They discovered that the durability of the carcass can be maintained by preventing the permeation of the carcass.

The belt layer 7 is composed of one or two belt plies 7A and 7B, in this example two belt plies 7A and 7B adjacent to each other inside and outside. Also, each belt ply 7A, 7B has an elastic modulus of 20.
A rubberized nylon belt cord of 0 kgf/mm2 or more is attached at an angle of 10° or more and 40° to the tire equator.
It consists of a code array arrayed at an angle of less than °.

Furthermore, the belt plies 7A and 7B are arranged in different directions such that the belt cords intersect with each other between the plies, thereby reducing the weight of the tire and increasing the tread rigidity due to the strong truss structure that intersects with each other. and provide the required steering stability and driving performance.

The end of the belt layer 7 is raised from the carcass 6 as the carcass 6 is curved into an arc at the shoulder part, and this raised part has sidewalls rising from the clinch apex 15 for reinforcing the bead part 3. Reinforcement layer 16 made of hard rubber forming part 4
Some of them are involved.

Note that when using an aromatic polyamide cord for the belt cord, as shown in FIG. 2, the belt ply 7
The distance A between each belt cord 7a, 7b of A, 7B is 0.
5 mm or more and 1 mm or less. As a result, the shearing stress acting between the belt plies 7A and 7B and the shearing stress concentrated at the ply ends can be effectively alleviated, making it possible to use aromatic polyamide fibers having poor rubber adhesion.

If the distance A is less than 0.5 mm, the stress relaxation effect will be poor, and if it exceeds 1 mm, the belt plies 7A, 7
The movement between B becomes excessive, reducing steering stability and increasing weight.

[0023] When a nylon cord is used for the belt, the distance A may be 0.3 mm to 0.6 mm, and therefore, it is preferable to use a nylon cord in order to reduce the weight.

Further, such a distance A can also be formed by interposing an independent intermediate rubber layer 12 between the belt plies 7A and 7B, as shown by the dashed line in FIG. A rubber material having a JISA hardness of 75° or more and 85° or less is used for stress relaxation.

[0025] Also, in the belt layer 7, as shown by the dashed line in Fig. 1, one or more band cords made of nylon fiber are attached at an angle of 10 degrees or less, preferably 5 degrees or less, with respect to the tire equator. It is also preferable to cover the entire surface with a band layer 10 that is continuously wound spirally in the tire circumferential direction at an angle. This can suppress lifting caused by, for example, centrifugal force associated with high-speed rotation, and reduce peeling between plies.

[0026]

[Specific example] Tire size 135/7 based on the specifications in Table 1
An 0R15 tire was prototyped based on the present invention, and the tire weight, handling stability, and durability of the prototype tire were compared with a comparative example. The results are shown in Table 1 as an index with Comparative Example Product 1 set as 100.

In Table 1, the smaller the tire weight ratio, the lighter the tire weight, and the larger the index, the better the steering stability and durability.

[0028]

[Table 1]

[0029]

【Effect of the invention】

As described above, the spare tire of the present invention has a carcass formed of a nylon monofilament cord, thereby reducing the tire weight while maintaining various tire performances.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a tread portion.

[Explanation of symbols]

2 Bead core 3 Bead part 4 Sidewall part 5 Tread section 6 Carcass 7 Belt layer 7A, 7B Belt ply 9 Inner liner 10 Band layer

Claims (1)

[Claims] [Claim 1] A cross ply comprising at least two carcass plies that extend from the tread part through the sidewall part and are folded back at the bead core of the bead part, and the carcass cords are inclined in opposite directions to each other at an angle of 28 to 38 degrees with respect to the tire equator. a carcass having a structure, and a belt layer disposed on the outside of the carcass in the tire radial direction and inside the tread portion, and consisting of a belt ply using an organic fiber belt cord,
In the spare tire, the carcass cord is made of nylon monofilament, and an inner liner having a thickness of 0.5 to 0.2 mm is attached to the inner surface of the carcass facing toward the inner cavity of the tire.