JPH11227425A - Pneumatic safety tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic safety tire in which the run-flat travelling performance is remarkably improved while the normal travelling performance at the time when the tire is filled with internal pressure is maintained at high levels. SOLUTION: In a pneumatic safety tire in which a side wall 16, a carcass layer 18, a belt layer 20, and a tread part 22 are arranged in order to reinforce the tire respectively, and a reinforcing rubber layer 24 of crescent-shaped cross section is provided on the inner peripheral face of the carcass layer 18 in the side wall 16, a side reinforcing layer 26 made of organic fiber cords made up of filaments of extreme high elastic modulus of 1000 kg/mm<2> or more, extends from below the end part of the belt layer 20 through inside the reinforcing rubber layer 24 to make a winding up around a bead ring 12, and extends along the outermost side of the carcass layer 18 up to below the end part of the belt layer 20. Both end parts of the reinforcing layer 26 and the end part of the belt layer 20 are arranged so as to be overlapped W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic safety tire which reinforces a tire side portion and enables good run flat running.

[0002]

2. Description of the Related Art A pneumatic tire is capable of run-flat running (that is, a punctured tire has a tire internal pressure of 0 kg / c).
even if the m ^2, a certain distance a vehicle can travel with peace of mind) tire (referred pneumatic safety tire) is the portion of the rim in an air chamber of the tire, mounted metal, synthetic resin annular core There are known a core type and a side reinforcement type in which a relatively hard rubber layer having a crescent cross section is arranged on the inner surface of the carcass from the bead portion of the tire sidewall to the shoulder region and reinforced. Of these two types, the core type has a high load-bearing capacity in run-flat driving, so it is intended for use in luggage-carrying vehicles and military vehicles where ride comfort is not an issue. However, they are small, and have been evaluated as appropriate for passenger cars that emphasize riding comfort.

[0003] Currently, pneumatic safety tires that are being developed are often side reinforced types.
On the inner surface of the carcass layer on the side wall, a relatively hard reinforcing rubber layer with a crescent cross section, one end of which overlaps with the belt layer across the carcass, and the other end overlaps with the rubber filler. Placement has been strengthened. If the tire punctures during running and the air escapes, the load is supported by the inherent rigidity of the sidewall reinforced with the reinforcing rubber layer, and although the speed must be slightly reduced, the run-flat running for a predetermined distance It can be carried out.

As described above, various side-reinforcement type safety tires have been conventionally proposed, but most of them are flat high-performance tires, that is, low in flatness (less than 60%) mounted on a sports car, Although it is for vehicles with relatively low load, run-flat running durability is not sufficient. The flattening rate is represented by {(tire height) / (tire width)} × 100 when mounted on the rim, and the flat tire refers to a tire having a flattening rate of less than 60%.

On the other hand, with the recent increase in demands on safety, safety tires are also required for general-purpose passenger car tires having an aspect ratio of 60% or more.

[0006] In the case of tires for general-purpose passenger cars, even if the load burden is relatively small, when the size of the passenger car becomes large, the load per tire becomes as large as about 500 kgf. In such a case, the deformation of the sidewall in the punctured state is further increased, and the sidewall is completely buckled by several times the dynamic load received during traveling, and the vehicle travels while repeating this. As a result, the bead portion on the sidewall is lifted up by the flange of the rim, and the skin rubber and the carcass folded portion sandwiched between the curved flange and the rubber filler are melted or torn by heat, thereby causing a puncture. Even after repairing the part that has become, it can no longer be used.

Further, in the prior art, a reinforcing rubber layer having a crescent cross section is mainly disposed inside the carcass layer of the side wall portion, and the carcass layer is usually formed of one or two layers in order to further increase the rigidity of the side wall portion. Need more 3-4 layers,
There is a problem in that the weight increases, and furthermore, the rolling resistance and the handling stability deteriorate.

On the other hand, in recent years, as the fuel economy of vehicles has been reduced, the weight of tires has been strongly required to be reduced, and the thickness of tire sidewalls has been increasingly reduced in order to reduce the weight of tires. Furthermore, it is naturally required to be able to perform run-flat running in which the internal pressure of the tire is 0 kg / cm ² , and at the same time, to perform in normal running when filling the internal pressure.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to realize a lighter weight while maintaining a high level of normal running performance when filling with an internal pressure, and to achieve a run flat compared to a safety tire having a conventional reinforcing rubber layer. It is an object of the present invention to provide a pneumatic safety tire having significantly improved running performance.

[0010]

In order to solve the above-mentioned problems, the present inventors have made intensive studies on the relationship between the tire sidewall portion and the run-flat running performance of the tire. The inventors have found that the object can be achieved by the following means such as disposing the layers on both sides of the carcass layer inside and outside the side wall, and have completed the present invention.

That is, (1) the pneumatic safety tire of the present invention has a sidewall in which a bead ring is buried at a tip portion extending radially inward from both ends of the cylindrical crown portion, and the crown portion extends from one of these sidewalls. And at least one fiber cord radial ply extending between the carcass layer and the other side wall of the carcass layer. A plurality of non-extensible belt layers, and a tread portion are sequentially arranged and reinforced respectively, and on the inner peripheral surface of the carcass layer of the sidewall, a pneumatic safety tire having a crescent-shaped reinforcing rubber layer in cross section. And the filament elastic modulus is 1000
kg / mm ² or more, a side reinforcing layer made of an organic fiber cord passes through the inside of the reinforcing rubber layer having a crescent cross section from below the belt layer end, and is wound up around the bead ring, and further along the outermost layer of the carcass layer. It is characterized in that it extends to below the end of the layer and that both ends of the side reinforcing layer overlap the ends of the belt layer. (2) In the above item (1), on the outer peripheral side of the belt layer,
Further, it is preferable that at least one belt reinforcing layer is disposed on the entire tread portion. (3) In the above item (1), the organic fiber cord constituting the side reinforcing layer is preferably at least one cord selected from the group consisting of aramid fiber and polybenzoxazole fiber. (4) In the above item (1), it is preferable that both end portions of the side reinforcing layer have an overlapping portion of 10 to 30 mm with an end portion of the belt layer. (5) In the above item (1), the angle of the organic fiber cord of the side reinforcing layer is preferably 0 to 30 ° with respect to the radial direction.

When the air from the pneumatic safety tire is deflated, the sidewall is bent and the tire is broken due to rubbing or the like, and the vehicle cannot run. Therefore, in the present invention, in a pneumatic tire provided with a reinforcing rubber layer having a crescent cross section on the inner peripheral surface of the carcass layer, the inner layer and the outermost layer of the carcass layer have extremely high tensile elastic modulus, for example, aramid fiber or polybenzo. Oxazole (PBO) fibers are arranged on both the inside and outside of the carcass layer in the side wall part, and the deformation of the side wall when air is evacuated, the compressive deformation inside the side wall, the crescent cross section of the inner peripheral surface of the carcass layer The super-high modulus fiber (amide fiber or PBO) inside the reinforcing rubber layer and the inside of the reinforcing rubber layer and the outermost super-high modulus fiber (aramid fiber or PBO) in the outermost layer are responsible for tensile deformation. It was done. Based on such new findings, a pneumatic safety tire having excellent run flat durability has been obtained without increasing the carcass layer.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, when air from a tire is released, a tensile stress acts on an outer side where a sidewall portion is bent, and a compressive pressure acts on an inner side. Therefore, a filament of an organic fiber cord used for a side reinforcing layer is used. As the fiber, a fiber having an ultra-high modulus of elasticity with high tensile and compressive modulus is used. This elastic modulus needs to be 1000 kg / mm ² or more. Any organic fiber having an ultra-high elastic modulus may be used as long as it satisfies the above elastic modulus conditions, and is not particularly limited. For example, aramid (aromatic polyamide), polybenzoxazole (PBO), or polyvinyl alcohol (PVA) may be used. Can be mentioned. Above all, aramid and / or polybenzoxazole are preferred from the viewpoint of elastic modulus. These filament fibers can be used alone, in combination of two or more kinds, or in combination with other filament fibers. In any case, it is necessary to satisfy the above elastic modulus.

The reinforcing rubber layer having a crescent cross section on the inner peripheral surface of the carcass layer used in the present invention suppresses the deflection of the sidewall when the air of the pneumatic safety tire escapes.
It is necessary to have a function (for example, high hardness) of suppressing the compression deformation inside the sidewall. Examples of the rubber component of the reinforcing rubber layer used to exhibit this function include natural rubber (NR), butadiene rubber (BR), and styrene-
Examples thereof include butadiene rubber (SBR) and isoprene rubber (IR). Among them, natural rubber and butadiene rubber are preferable from the viewpoint of the effect.

In the pneumatic safety tire according to the present invention, it is preferable that both end portions of the side reinforcing layer have an overlapping portion of 10 to 30 mm with an end portion of the belt layer. When the overlapping portion is less than 10 mm, the elastic modulus of the tire is unfavorable, and when it exceeds 30 mm, the weight of the tire is unfavorable.

In the pneumatic safety tire of the present invention, the angle of the organic fiber cord of the side reinforcing layer for reinforcing the side wall is preferably 0 to 30 ° with respect to the radial direction. If the angle exceeds 30 °, the effect of suppressing the deflection of the side wall is undesirably reduced.

In the pneumatic safety tire of the present invention, it is preferable that at least one belt reinforcing layer is further disposed on the entire outer surface of the belt layer on the entire tread portion from the viewpoint of tire durability. This belt reinforcing layer is formed by being spirally and endlessly wound so as to be substantially parallel to the tire circumferential direction.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
A description will be given using examples and comparative examples.

FIG. 1 shows an example of a schematic sectional view of this pneumatic safety tire. In the pneumatic safety tire 10 of the present invention, a sidewall 16 in which a bead filler 14 and a bead ring 12 are buried is connected to a tip portion from both ends of a cylindrical crown portion toward a radially inner side.
A carcass layer 18 formed of at least one fiber cord radial ply extending from one side to the other side wall through the crown portion, and both ends of which are wound around the bead ring 12 in the axially outward direction and fixed. A plurality of non-extensible belt layers 20 are provided on the outer periphery of the crown portion of the carcass layer 18, and at least one belt reinforcing layer (cap layer layer), not shown, is provided on the outer peripheral side of the belt layer as needed, over the entire tread portion. , And the tread portion 22 are sequentially arranged to reinforce each other.
The inner peripheral surface of the carcass layer 18 has a crescent-shaped reinforcing rubber layer 24 (for example, having a maximum thickness of 7 mm,
Side reinforcing layer 26 (for example, the cord angle of this layer is 0 to 30 ° with respect to the radial direction) comprising an organic fiber cord of an ultrahigh modulus filament (for example, PBO) having a hardness of 80 ° or more and 1000 kg / mm ² or more. ) Passes through the inside of the reinforcing rubber layer 24 having a crescent cross section from below the belt layer end,
Winding the beet ring 12 around, the carcass layer 18
Along the outermost edge of the belt layer and further down to the edge of the belt layer,
In addition, they are arranged so as to have overlapping portions W (for example, 10 to 30 mm) between both end portions of the side reinforcing layer and end portions of the belt layer.

Various evaluation methods used in Examples and Comparative Examples are as follows. -Hardness is represented by JIS A and JIS K6301-1.
994.

The run flat durability is such that the air pressure is 0 kg / cm ² only on the right front wheel of a 2500 cc class domestic passenger car.
The tires are mounted and run at a constant speed of 20 km / h. The driver detects the occurrence of abnormal vibration (endurance limit) due to tire failure, calculates from the travel distance leading to the failure, and controls (Comparative Example 1). Was represented by an index with 100 as the index. The larger the value, the better the run flat durability. (Examples 1 to 3) (Comparative Examples 1 and 2) The pneumatic safety tire used has a tubeless structure with a size of 205 / 55R15, and as a carcass ply (body ply) layer, two-ply polyethylene terephthalate of 1670 dTEX is used. Use 50 layers / 5cm layer 2
A crescent-shaped reinforcing rubber layer, a rubber having a hardness of 80 ° after vulcanization and a maximum thickness of 7 mm with a composition according to Table 1 and a belt layer having a 1 × 5 structure and a wire diameter of 0 mm was used. .25 mm steel cords were driven 40 threads / 5 cm, and the steel cord angle was 2 with respect to the tire circumferential direction.
A steel belt layer of 0 ° was used in a two-piece structure, and 1400 dTEX of 2
The number of the twisted nylon cord is 40 / 5cm,
The nylon cord was used in a cap layer structure in which the angle was 0 ° with respect to the tire circumferential direction.

Further, according to Table 2, a tire was produced by obtaining the elements of the outermost layer of the carcass of the pneumatic stable tire and the overlapping width of the upper end of the side reinforcing layer with the end of the belt layer according to Table 2. The run flat durability of the tire was measured. Table 2 shows the results.

The durability at the time of filling the internal pressure of all the test tires was at a level without any problem.

[0024]

[Table 1]

[0025]

[Table 2]

As described above, it can be seen that the pneumatic stable tire of the present invention has excellent run-flat durability while maintaining the durability at the time of filling the internal pressure.

In the case where a nylon fiber having a low modulus of elasticity is used as the filament of the side reinforcing layer (Comparative Example 1), and when there is no overlap between the upper end portion of the reinforcing layer and the end portion of the belt layer (Comparative Example 2), run-flat durability is used. The sex worsens.

[0028]

As described above, the pneumatic safety tire according to the present invention has a reinforcing rubber layer, an outermost layer of the carcass layer, and a cord having an ultra-high modulus of elasticity widely inserted into the innermost layer of the carcass layer. It has an excellent effect that the durability during internal pressure filling is maintained, and the lightness and run flat durability are improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an exemplary pneumatic safety tire of the present invention.

[Sign]

DESCRIPTION OF SYMBOLS 10 Pneumatic safety tire 12 Bead ring 14 Bead filler 16 Side wall 18 Carcass layer 20 Belt layer 22 Tread part 24 Reinforcement rubber layer 26 Side reinforcement layer W Overlap between both ends of side reinforcement layer and belt layer end.

Claims (5)

[Claims] 1. A side wall having a bead ring buried at a tip portion thereof extends from both ends of a cylindrical crown portion toward a radially inner side, and a gap extending from one of the sidewalls to the other sidewall through the crown portion. A carcass layer made of at least one fiber cord radial ply and having both ends rolled up in the axial direction around the bead ring and fixed, a plurality of non-extensible belt layers on the outer periphery of the crown portion of the carcass layer, And a tread portion arranged sequentially to reinforce each other, and a pneumatic safety tire having a crescent-shaped reinforcing rubber layer on the inner peripheral surface of the carcass layer of the side wall, and a filament elastic modulus of 1000 kg / mm. through the inside of the reinforcing rubber layer of the crescent cross-sectional shape of the side reinforcing layer of ^two or more organic fiber cord from the belt layer end part Round winding the bead ring, along the outermost layer of the carcass layer,
The pneumatic safety tire further extends to below the end of the belt layer, and is disposed so that both ends of the side reinforcing layer overlap the end of the belt layer. 2. The pneumatic safety tire according to claim 1, wherein at least one belt reinforcing layer is further disposed on an outer peripheral side of the belt layer over the entire tread portion. 3. The pneumatic safety according to claim 1, wherein the organic fiber cord constituting the side reinforcing layer is at least one cord selected from the group consisting of aramid fiber and polybenzoxazole fiber. tire. 4. The pneumatic safety tire according to claim 1, wherein both end portions of the side reinforcing layer have an overlap portion of 10 to 30 mm with an end portion of the belt layer. 5. The pneumatic safety tire according to claim 1, wherein the angle of the organic fiber cord of the side reinforcing layer is 0 to 30 ° with respect to a radial direction.