JPH03213404A - Spare tire - Google Patents

Abstract

PURPOSE:To lighten a spare tire and improve the durability thereof by forming a belt layer of belt cords consisting of aromatic polyamide fibers to define a distance between the belt cords, while binding the outer surface by the belt layer winding a nylon cords spirally around the outer surface. CONSTITUTION:A toroidal carcass 6 is provided between bead sections 3 of a spare tire 1 while a belt layer 9 and a band layer 10 are sequentially windingly attached between the outside of the carcass 6 and the inside of a tread section 5. Then, the belt layer 9 is formed of a plurality of belt plies 9A, 9B while a radial distance A between respective belt cords 9a, 9b made of aromatic polyamide fibers in adjacent belt plies 9A, 9B is set within the extent of 1mm-2mm. The band layer 10 is formed of a band ply 10A, winding a proper number of band cords 10a of nylon fibers in a continuous spiral in the circumferential direction of the tire, and covers the whole surface of the belt layer 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a spare tire that has excellent steering stability, high-speed running performance, etc., improved durability, and reduced tire weight.

[Conventional technology]

As vehicles become faster and more capable, there is a growing demand for spare tires that are used in the event of a puncture to have the same high tire performance as regular tires. The transition to is being strongly promoted.

On the other hand, in a conventional spare tire having such a radial structure, for example, as shown in Fig. 4, the carcass case A is firmly tightened with a belt layer B using a steel belt cord, and the tread rigidity is greatly increased. By increasing the width, it is intended to improve handling stability, high-speed running performance, and wear life due to rolling resistance. Note that belt layer B is
Each belt ply b
, b are arranged with different ply widths.

[Problem to be solved by the invention]

However, since such spare tires are used at a higher internal pressure, e.g. 4.2 ktrf/cs, than normal tires, the tread shoulder area, which has a poor hoop effect due to the different ply widths, suffers from failure. Uniform outer diameter growth tends to occur (and the resulting temperature rise induces ply edge separation. Furthermore, belt layers using steel cords have a large mass, so they are easily lifted by centrifugal force during high-speed rotation. , together with the above-mentioned outer diameter growth, significantly reduces durability.

In addition, the use of such steel cords increases the total weight of the tire, which increases the weight burden on the vehicle during normal driving with the spare tire stored in the trunk, etc., and reduces overall vehicle output and reduces fuel efficiency. worsen performance.

In the present invention, the belt layer is formed using an aromatic polyamide fiber cord, and a band layer made of a nylon fiber cord is spirally wound on the outside of the belt layer, so that various tire performances are not impaired ← Durability performance The objective is to provide a spare tire that can improve the performance of tires and reduce the weight of wide tires.

In order to achieve the above object, the spare tire of the present invention comprises at least one carcass ply which is folded from the tread part through the sidewall part and around the bead core of the bead part. a carcass, and a belt layer consisting of at least two inner and outer belt plies arranged on the outside in the tire radial direction and inside the tread of the carcass and having belt cords made of aromatic polyamide fibers arranged parallel to each other. , a band layer disposed on the outside of the belt layer and substantially in between the belt layer; The distance A is 1 mm or more and 2fi or less, and the band layer is formed by continuously winding a band cord made of nylon fiber around the belt layer at least once in the circumferential direction of the tire. There is.

In addition, the belt layer has a rubber layer interposed between each belt cord of adjacent belt plies with a JISA hardness of 75° or more and 8.
It is preferable to use a rubber material having an angle of 5° or less.

[Effect]

In the spare tire constructed in this way, the belt layer is formed by a belt cord using high modulus organic fibers, that is, aromatic polyamide fibers, so it can provide the necessary tread rigidity, improve tire performance, and reduce tire weight. can be significantly reduced.

In addition, since the belt layer regulates the distance between the belt cords of adjacent belt plies and restrains the outer side with the band layer, it alleviates the shear stress acting between the plies and at the ends of the plies, while effectively preventing the lifting. can be suppressed,
This makes it possible to use aromatic polyamide fibers, whose range of use has been limited in the past due to poor adhesion to rubber, and to use an intermediate belt ply, while further improving durability. .

〔Example〕

An embodiment of the present invention will be described below based on 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 from the bead portion 3 toward the tire radius, and a tread portion 5 connecting the upper ends of the sidewall portion 4. A toroidal carcass 6 is stretched between the bead portions 3 and 3, and a belt layer 9 and a band layer 10 are sequentially wound on the outside in the radial direction of the tire and inside the tread portion 5. .

The carcass 6 is formed from at least one carcass ply 6A, in this example, one carcass ply 6A, in which carcass cords are arranged at an angle of 70 to 90 degrees with respect to the tire equator. Both ends of the main body part 6a leading to the part 3 are folded back around the bead core 2 from the inside to the outside and locked. Also, a bead apex 8 is disposed between the main body portion 6a and the folded portions 6b at both ends thereof, and extends from the bead core 2 in a tapered shape outward in the radial direction, extending from the bead portion 3 to the sidewall portion 4 and reinforcing the bead apex 8. There is.

Further, as the carcass cord, a polyester fiber cord having excellent dimensional stability and high heat resistance and fatigue resistance is suitably used in this example, but organic fiber cords such as nylon and rayon may also be used.

The belt layer 9 is composed of at least two belt plies 9A and 9B, in this example two belt plies 9A and 9B that are adjacent to each other inside and outside, and each belt ply 9A and 9B is formed between the paths. Therefore, the belt layer 9 can tighten the recarcass 6 almost uniformly over the entire car, and can suppress uneven outer diameter growth in the shield portion when high internal pressure is filled.

Each belt ply 9A, 9B is made by twisting aromatic polyamide fibers together and has an initial elastic modulus of 600 kg.
f/Tsuru A cord array body in which belt cords drawn at least 2 or more are arranged at an angle of 10° or more and 30° or less with respect to the tire equator, and belt plies 9A and 9B are arranged so that each belt cord is stretched between They are arranged in different directions so that they intersect with each other. Therefore, the belt layer 9 has a strong truss structure in which high-modulus belt cords made of aromatic polyamide fibers intersect with each other, thereby reducing the weight of the tire and greatly increasing the tread rigidity. Provides high-speed driving performance.

The ends of the belt layer 9 are raised from the carcass 6 as the carcass 6 is curved into an arc at the sill part, and in this raised part there is a sidewall part 4 rising from the clinch apex 15 for reinforcing the bead part 3. There is a part of the reinforcing layer 16 made of hard rubber forming the .

In the present invention, as shown in FIG. 2, each belt cord 9a of adjacent belt plies 9A and 9B is
, 9b is the radial distance between belt cords A
is 1fi or more and 2mm or less, which makes it possible to use aromatic polyamide fibers, which have poorer rubber adhesion than conventional steel fibers, and to adopt a belt structure in which the brie width of each belt ply 9A and 9B is adjusted. is possible.

That is, by expanding and contracting the rubber layer 11 interposed between the belt cords 9a and 9b, the shear stress acting between the belt plies 9A and 9B and the shear stress concentrated at the ply ends can be effectively alleviated, and the cord array This can further improve durability compared to conventional tires. Therefore, distance A is 1
If it is less than m, the stress relaxation effect will be poor and the durability will be reduced, and if it exceeds 2 dragons, the movement between the belt plies 9A and 9B will be excessive, impairing the steering stability, while increasing the internal temperature and conversely reducing the durability. do. Note that in conventional tires, the distance A is in the range of 0.3 tm to 0.6 tm.

Further, in this example, such a distance A is the belt ply 9A,
It is formed by laying an independent intermediate rubber layer 12 between 9B, and the intermediate rubber layer 12 has a JISA hardness of 75 degrees or more and 8
It is preferable to use a rubber material having an angle of 5° or less. Note that the rubber layer 11 is attached to each belt ply 9A, as shown in FIG.
It can also be formed by the covering portion 13A of the topping rubber 13 by increasing the thickness of the topping rubber 13 of 9B.

Further, the belt layer 9 is covered with a band layer 10.

The band ll110 consists of one or more band cords 10a made of nylon fiber at a distance of 10 mm from the tire equator.
In this example, the band ply IOA is wound continuously in a helical manner in the tire circumferential direction at an angle of less than 5 degrees, preferably less than 5 degrees, and is formed substantially circularly with the belt layer 9. The belt layer 9 is coated over its entire surface. In this example, the band cord 10a is continuously wound at least once in the tire circumferential direction from one end of the band bridle IOA to the other end.

Therefore, the band layer 10 has a low number of cords and the belt layer 9
For example, lifting caused by centrifugal force caused by high-speed rotation can be suppressed, and peeling between 0.0 and 2.5 mm can be greatly reduced. In particular, since the nylon cord has heat shrinkability, it has a great effect of suppressing the lifting, and also has a lower modulus than the belt cords 9a and 9b, so it can alleviate the difference in rigidity between the nylon cord and the tread rubber. Furthermore, by reducing the number of discontinuities, the uniformity of the tire can be improved, and since it has excellent adhesion to rubber, the overall durability of the tire can be greatly improved.

〔Concrete example〕

A prototype tire with the tire structure shown in Figure 1 and a tire size of T135/70R16 was manufactured based on the specifications in Table 1,
The tire weight, handling stability, and durability of the prototype tire were compared with those of a conventional spare tire with a radial structure, and the results are shown in Table 1 as an index with the conventional tire set as 100.

〔Effect of the invention〕

The spare tire of the present invention has a belt layer made of belt cords made of aromatic polyamide fibers, so it can provide high tread rigidity, improve various tire performances, and significantly reduce the tire weight. It can be reduced to Moreover, since the belt layer regulates the distance between the belt cords of adjacent belt plies and its outer surface is restrained by the band layer made of spirally wound nylon cords, durability can be greatly improved.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing one embodiment of the present invention, Fig. 2 is an enlarged sectional view of the belt layer, Fig. 3 is a sectional view showing another embodiment of the belt layer, and Fig. 4 is a sectional view of the conventional belt layer. FIG. 2 is a cross-sectional view showing the technique. 2-bead core, 3--bead part, 4-sidewall part, 5--tread part, 6-carcass,
6A-Carcass ply, 9-Belt layer, 9A, 9B-
Belt braai, 9a, 9b-belt cord, 10-band layer, 10a-band cord, 12-rubber layer.

Claims (1)

[Scope of Claims] 1. A carcass consisting of at least one carcass ply that is folded back around a bead core of a bead portion from a tread portion through a sidewall portion, and a carcass disposed outside the carcass in the tire radial direction and inside the tread portion. a belt layer consisting of at least two inner and outer adjacent belt plies in which belt cords made of aromatic polyamide fibers are arranged parallel to each other; the belt layer has a belt layer having a belt cord distance A of 1 mm, which is a radial distance between each belt cord of adjacent belt plies.
or more and 2 mm or less, and the band layer is formed by continuously winding a band cord made of nylon fiber around the belt layer at least once in the circumferential direction of the tire. 2. The spare tire according to claim 1, wherein the rubber layer of the belt layer interposed between each belt cord of adjacent belt plies is formed of a rubber material having a JISA hardness of 75° or more and 85° or less.