JPH11301224A - Pneumatic safety tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize good run-flat traveling without injuring comfortability to ride during usual internal pressure traveling by passing at least one carcass plies through between a pair of bead cores and terminating at a neighborhood of the bead cores. SOLUTION: A carcass ply 2 passes through between a pair of bead cores 8a, 8b and is terminated to a neighborhood of the bead cores in a bead portion 8 comprising a pair of upper and lower bead cores 8a, 8b against a tire-radial direction. Preferably, the carcass ply 2 passes through between a pair of bead cores 8a, 8b and is bent down in the bead portion 8 comprising a pair of upper and lower bead cores 8a, 8b against the tire-radial direction, or the carcass ply 2 passes through a tire-axial outside of a rubber reinforcing layer and an axial inside of a bead filler 9 and an edge of the carcass ply 2 is not positioned at an axial outside of the bead filler 9. Thereby, it is prevented that an extreme compressive strain is added to a carcass ply bent portion of the bead portion during run-flat traveling.

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 having both durability and riding comfort, and more particularly, to a good run-flat running without impairing the riding comfort during normal internal pressure running. Related to pneumatic safety tires.

[0002]

^2. Description of the Related Art When the tire internal pressure is 0 kg / cm ² ,
As a pneumatic tire capable of so-called run-flat running (referred to as a "pneumatic safety tire"), a side reinforced type in which a relatively hard rubber layer having a crescent cross section is arranged on the inner surface of a carcass and reinforced is known. . This side-reinforcement type has a comparatively good reputation for use in vehicles where the load on the load is relatively light and emphasis is placed on riding comfort.

In the side reinforcing type, a relatively hard reinforcing rubber layer having a crescent cross section is disposed on the inner surface of the carcass layer in the side wall such that one end of the reinforcing rubber layer overlaps with a rubber filler, and the reinforcing rubber layer is reinforced. I have. 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.

[0004]

However, at present, even the above-mentioned side-reinforced type pneumatic safety tire still cannot be said to have a sufficient run-flat running property. That is, in the case of tires for general-purpose passenger cars, the load burden is relatively small, but when the size of the passenger car is 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 due to several times the dynamic load received during traveling, and the vehicle travels while repeating this. As a result, the bead portion on the side wall is pushed 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 the puncture of the puncture. Even if the part that caused the problem is repaired, subsequent use is impossible.

[0005] When a safety pneumatic safety tire of a general-purpose tire size is run under run-flat conditions, the internal temperature of the tire becomes 200 ° C or higher, so it is said that the tire has excellent heat resistance. Even terephthalate (PET) does not have sufficient adhesiveness to rubber at high temperatures. Specifically, in the case of a tire to which a PET carcass is applied, failure during run flat running is caused by peeling at the PET / adhesive layer interface. Is the main thing. Therefore, it is at a low level in terms of run flat durability.

[0006] In order to solve this problem, it is conceivable to use a steel carcass ply.
The rigidity of the steel carcass is remarkably increased, and it is difficult to achieve both run-flat durability and riding comfort during normal internal pressure charging running. That is, even in a pneumatic safety tire capable of run-flat running in which the internal pressure of the tire is 0 kg / cm ² , the performance in normal running when filling the internal pressure is naturally required.

It is an object of the present invention to provide a pneumatic safety tire that achieves both durability and ride comfort, and in particular, for a passenger car that enables good run flat running without impairing the ride comfort during normal internal pressure running. It is to provide a pneumatic safety tire.

[0008]

Means for Solving the Problems The present inventors have paid attention to the point that extreme compressive strain is applied to the folded portion of the carcass ply of the bead portion due to its deformation during run-flat running of the pneumatic safety tire so far. As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by the following means such as adopting a specific carcass ply structure, and have completed the present invention.

(1) That is, the pneumatic safety tire of the present invention comprises a pair of left and right bead portions and at least one carcass ply composed of a layer in which a plurality of parallel cords are embedded in a covering rubber. A carcass part straddling between the parts, a belt part composed of a plurality of layers of steel belt plies arranged radially outward of the carcass part, and an annular tread part arranged radially outside of the belt part in the tire radial direction And a pair of sidewall portions disposed on the left and right sides of the tread portion, and a rubber reinforcing layer having a crescent-shaped cross-section disposed on the sidewall portion. Each of the bead portions includes a pair of bead cores, and the at least one carcass ply passes between the pair of bead cores and ends near the bead cores. And wherein the door.

(2) In the pneumatic safety tire,
A pneumatic safety tire in which the carcass ply is folded down between the pair of bead cores.

(3) In the pneumatic safety tire,
A bead filler is arranged radially outside the bead portion in the tire radial direction, and the carcass ply passes through the tire axial direction outside of the rubber reinforcing layer and the axial direction inside of the bead filler, and the bead filler axially outside. It is a pneumatic safety tire where the carcass ply end is not located.
(4) The pneumatic safety tire as described above, wherein the embedded cord of the carcass ply is a steel cord and the breaking elongation is 3.5% or more.

The reinforcing material applied to the carcass ply is subjected to both tensile and compressive strains during run-flat running in the conventional normal ply structure. Therefore, depending on the material and the level of the strain, failure due to buckling of the ply material occurs. In many cases. However, due to the carcass ply structure of the present invention, the strain in the carcass ply is dominant in the tensile direction, and the material applied to the ply generally has a higher tensile strength in the tensile direction than the compression. Almost gone. In addition, by disposing the ply only at the position where the strain in the tensile direction is dominant, the bending strain borne by the side rubber reinforcing layer during run flat running is reduced by an increase in the load due to the tension of the carcass ply, and the rubber reinforcing layer Rubber weight can be reduced.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a buried cord of at least one carcass ply used in the present invention, either a steel cord or an organic fiber cord can be used.

When a steel cord is used, it is preferable to use a high elongation steel cord. If a steel cord having a low elongation is used, the rigidity of the carcass is remarkably increased, and it is difficult to achieve both run-flat durability and riding comfort during normal internal pressure charging traveling. The high elongation steel cord that can be suitably used in the present invention will be described in detail. First, the elongation at break when taken out from a tire and measured is preferably 3.5% or more, more preferably 4.0% or more. It is. If the elongation is less than 3.5%, the steel cord itself is not preferable in terms of fatigue durability. A cord having a high breaking elongation can be obtained by increasing the amount of molding with respect to the filament pitch length of the cord.

Alternatively, the elongation at break obtained by subjecting the filament drawn by die drawing to a bluing treatment at, for example, 380 to 430 ° C. is 3.
A cord composed of a filament of 5% or more, preferably 4.0% or more may be used for the carcass ply. Specifically, a cord (for example, 1 + n, 1 × n) obtained by twisting one or a plurality of blue-treated filaments
(Structure), or one or a plurality of drawn cords may be subjected to bluing processing. It is preferable to increase the adhesiveness by performing an adhesive treatment after the bluing treatment.

The above-described steel cord has significantly improved compression fatigue resistance as compared with the conventional steel cord, and can absorb the compression input by deformation of the steel cord itself. This significant improvement in compressive fatigue resistance overcomes the drawbacks of steel cords, while other features such as high flexural rigidity of steel cords can be used. Safety tires become feasible.

The structure of such a steel cord preferably has a 1 × n structure, where n is 2 to 7, more preferably 3 to 7.
6 is a natural number. If n exceeds 7, the arrangement of the filaments is likely to be lost, and as a result, the permeability of the matrix rubber into the inside of the steel cord is reduced, the uniformity as a cord is deteriorated, and a high elongation at break becomes difficult to obtain. It is not preferable in terms of the above. The filament diameter of the filament fiber of the steel cord is preferably 0.125 to
0.275 mm, more preferably 0.125 to 0.23
0 mm, and if the diameter is less than 0.125 mm,
Since the wire is difficult to be drawn and the tensile strength is hard to be obtained, the cord strength is reduced, and as a result, the strength of the case member of the tire is reduced. On the other hand, if it exceeds 0.275 mm, the fatigue resistance is deteriorated, which is not preferable.

Next, when an organic fiber cord is used as the embedded cord of the carcass ply, since the tire temperature during run-flat running becomes 200 ° C. or higher, the organic fiber having a heat-resistant stability having a melting point of 245 ° C. or higher is used. It is preferable to use 66-nylon (66N
y), 46-nylon (46Ny), polyethylene terephthalate (PET), polyethylene-2,6-naphthalate (PEN), aramid, rayon, polybenzoxazole (PBO), polyolefin ketone (PO
K) and the like.

The rubber component used for the carcass ply is not particularly limited. For example, natural rubber (NR), butadiene rubber (BR), styrene-butadiene rubber (SB)
R) and isoprene rubber (IR), of which natural rubber and butadiene rubber are preferred. In addition, compounding agents usually used in the rubber industry, for example, a reinforcing agent such as carbon black, a vulcanizing agent, a vulcanizing aid, a vulcanization accelerator, an antioxidant, a softening agent, and the like can be appropriately provided. Of course it is. By adjusting the type and amount of carbon black, the amount of sulfur, the amount of oil, and the like with respect to the rubber, the tensile stress at 50% elongation is preferably adjusted to 0.5 to
3.0 MPa, more preferably 0.5 to 2.0 MPa. If the tensile stress of the rubber layer is lower than 0.5 MPa, the durability near the end of the belt and the end of the carcass ply will usually be inferior in running under internal pressure, and failure such as separation between the belt and the carcass will be caused. on the other hand,
If it is higher than 3.0 MPa, it is not possible to improve the riding comfort during normal internal pressure running.

In the pneumatic safety tire of the present invention,
As shown in FIG. 1 (a), the carcass ply 2 has a pair of bead cores 8a, 8b in a bead portion 8 comprising a pair of upper and lower bead cores 8a, 8b in the tire radial direction.
And ends near the bead core. Preferably, the carcass ply 2 is folded down at a bead portion 8 composed of a pair of upper and lower bead cores 8a, 8b in the tire radial direction, between the pair of bead cores 8a, 8b, or outside the rubber reinforcing layer in the tire axial direction. The bead filler 9 passes through the inside of the bead filler 9 in the axial direction and
The carcass ply end is not positioned outside in the axial direction. In the present invention, as shown in (b) of FIG. 1, the carcass ply 2 may pass between the bead cores 8a and 8b, and may end for 8 minutes again after passing through 8b. By adopting such a carcass ply structure, it is possible to solve the problem of the conventional structure in which an extremely compressive strain is applied to the folded portion of the carcass ply in the bead portion during run flat running, which leads to failure of the ply material, and at the same time, the side rubber The weight of the reinforcing layer can be reduced.

Regarding the physical properties of the rubber composition used for the rubber reinforcing layer on the side, the tensile stress (M ₅₀ ) at 50% elongation is 2.0 to 9.0 MPa, and the tensile stress at 100% elongation (M _100). ) Is preferably 4.0 to 15.0 MPa. Further, _{M 50} with respect to the bead filler in _{2.0~12.0MPa, M 100} is 4.0
Preferably, it is １７17.0 MPa.

In the pneumatic safety tire of the present invention,
As shown in FIG. 2, a reinforcing layer 10 independent of the carcass ply 2 may be provided outside the bead filler 9 in the tire axial direction. This reinforcing layer 10 can be a reinforcing layer made of, for example, a textile cord or a steel cord and rubber having an angle of 0 to 45 ° with respect to the tire radial direction.

The pneumatic safety tire of the present invention can be manufactured by a conventional method. The green tire is vulcanized by applying the carcass ply structure according to the present invention to obtain a desired pneumatic safety tire.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structures of the pneumatic safety tires of the examples and comparative examples will be described below with reference to the drawings. The cross-sectional view of the tire shown in FIG. 3 shows a test passenger car tire 1 having a tire size of 225/60 R16. The carcass 2 is composed of two or three plies arranged in a direction substantially perpendicular to the equatorial plane 0 under the conditions shown in Tables 3 and 4 below, and both end portions thereof are a pair of upper and lower bead cores 8a in the tire radial direction. ,
8b, the pair of bead cores 8
The carcass ply end 2 ′ is not positioned on the axially outer side of the hard rubber bead filler 9 which is folded down between a and 8 b and buried in a tapered shape.

On the inner peripheral surface of the side portion 5 of the carcass 2, a rubber reinforcing layer 7 having a crescent-shaped cross section (Shore A hardness 80 °, maximum thickness 13 mm) is provided with a bead filler 9 via the carcass 2.
Are arranged over the entire side part 5 from the position overlapping with. Reference numeral 3 denotes a tread, and reference numeral 6 denotes an air-impermeable inner liner. The belt 4 includes two steel cords each having a twist structure of 1 × 5 inclinedly arranged at an angle of 26 ° with respect to the equatorial plane 0 (first belt layer 4a and second belt layer 4b).
Are overlapped so that their codes cross each other.

For comparison, a prototype pneumatic safety tire having a conventional ply structure shown in FIG. 4 was also produced (Comparative Examples 1 and 2). In the tires of these comparative examples, the carcass 2 used under the conditions shown in Tables 3 and 4 below was used.
As shown in the figure, both ends of the carcass ply are bead rings 8
To form a winding end 2 ′, and a bead filler 9 made of hard rubber is tapered between the carcass 2 on the bead core 18 and the ply winding end 2 ′. All other conditions such as the structure are the same as those of the embodiment.

The rubber reinforcing layer having a crescent cross section and the rubber composition of the carcass ply are shown in Tables 1 and 2 below.
As shown in FIG.

[0028]

[Table 1] 1) BR01 manufactured by JSR Corporation 2) FEF 3) Spindle oil 4) Noxeller NS (trade name, Ouchi Shinko Chemical Industry Co., Ltd.)
5) Nocrack 6C (trade name, Ouchi Shinko Chemical Co., Ltd.)
_{Ltd.) M 50 = 4.5MPa M 100 =} 10.5MPa

[0029]

[Table 2] 1) HAF 2) Spindle oil 3) Noxeller CZ (trade name, Ouchi Shinko Chemical Industry Co., Ltd.)
4) Nocrack 6C (trade name, Ouchi Shinko Chemical Industry Co., Ltd.)
5) The active ingredient contains 10% as a cobalt metal. M ₅₀ = 2.4 MPa M ₁₀₀ = 4 MPa

Various evaluation methods used for the tires of the examples and comparative examples are as follows. (A) Run flat durability After assembling the rim at an internal pressure of 3.0 kg / cm ² and leaving it at room temperature of 38 ° C. for 24 hours, the core of the valve was removed and the internal pressure was reduced to 0 kg / cm ^2.
cm ² , a drum running test was performed under the conditions of a load of 570 kg, a speed of 89 km / h, and a room temperature of 38 ° C. The running distance until the occurrence of the failure at this time was defined as run flat durability, and the value of Comparative Example 1 was set to 100 and indicated as an index. The larger the index, the better the run flatness.

(B) Ride comfort performance On-the-spot running under normal internal pressure, the sensory evaluation by the driver was performed. The evaluation was expressed as an index with the value of Comparative Example 1 being 100. The larger the index, the better the ride comfort performance.

(C) Weight of Reinforced Rubber Layer The value of Comparative Example 1 was expressed as an index with the value being 100. The higher the index, the higher the weight.

[0033]

[Table 3] 1) The total elongation at break measured in accordance with JIS G3510-1992.

[0034]

[Table 4]

As shown in Tables 3 and 4, it can be seen that the pneumatic safety tire of the present invention has greatly improved run-flat running performance without impairing the riding comfort in normal running when filling with internal pressure. .

[0036]

As described above, in the pneumatic safety tire of the present invention, by adopting a specific carcass ply structure, the performance in normal running at the time of filling the internal pressure, particularly the riding comfort performance is improved. It is possible to obtain the effect that the level is maintained at a level and the run flat running performance is greatly improved. Further, in obtaining such an effect, the weight of the rubber reinforcing layer on the side can be reduced.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing a ply structure in a bead portion of an example pneumatic safety tire of the present invention.

FIG. 2 is a partial cross-sectional view showing a ply structure in a bead portion of another example pneumatic safety tire of the present invention.

FIG. 3 is a cross-sectional view of the pneumatic safety tire according to the embodiment.

FIG. 4 is a sectional view of a conventional pneumatic safety tire.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pneumatic safety tire 2 Carcass 2 'Carcass ply end 3 Tread 4 Belt 4a First belt layer 4b Second belt layer 5 Side portion 6 Inner liner 7 Rubber reinforcing layer 8 Bead portion 8a, 8b Bead core 9 Bead filler 18 Bead core

Claims (4)

[Claims] A pair of left and right bead portions, a carcass portion in which at least one carcass ply composed of a layer in which a plurality of cords arranged in parallel are embedded in a covering rubber extends between the bead portions, A belt portion comprising a plurality of layers of steel belt plies arranged radially outward of the portion,
An annular tread portion disposed radially outward of the belt portion in the tire radial direction; a pair of sidewall portions disposed on the left and right sides of the tread portion; and a crescent-shaped rubber reinforcement disposed on the sidewall portion. A pneumatic safety tire comprising a pair of layers, each of the pair of left and right bead portions includes a pair of bead cores, and the at least one carcass ply passes between the pair of bead cores and ends near the bead cores. A pneumatic safety tire characterized in that: 2. The pneumatic safety tire according to claim 1, wherein the carcass ply is folded down between the pair of bead cores. 3. A bead filler is disposed outside the bead portion in the tire radial direction, and the carcass ply passes through the rubber reinforcing layer in the tire axial direction and the bead filler in the axial direction, and includes the bead filler shaft. The pneumatic safety tire according to claim 1, wherein the carcass ply end is not located outside in the direction. 4. The pneumatic safety tire according to claim 1, wherein the embedded cord of the carcass ply is a steel cord, and the breaking elongation thereof is 3.5% or more.