JPH06227216A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To enhance the comfortableness and high speed cornering performance without increase of the weight by forming a bead core through winding of a single element wire, arranging bead-toe reinforced rubber stocks in row (s) in the neighborhood of the bead core, and reinforcing them consolidatedly using a chafer. CONSTITUTION:A bead core 12 is formed by winding a single element wire of metal continuously. In the area of bead core 12 oriented inward in the tire axial direction, bead-toe reinforced rubber stocks 18 of JIS hardness between 80-98 deg. are arranged in row (s), wherein the tire axial direction width L2 is set to the range between 0.5-2.0 times as large as the bead core width L3. The tire axial direction width L1 from the tire axial direction exterior end of the bead core 12 to the tire axial direction interior end of the bead part 20 is set to 1.3-3.0 times as large as the bead core width L2. The radial direction inside area and the tire axial direction side area of the bead-toe reinforced rubber stock 18 and the bead core 12 are reinforced consolidatedly by a chafer 22 consisting of organic fiber cords.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire, and more particularly to a pneumatic radial tire capable of improving turning performance when a vehicle is traveling at high speed and improving riding comfort.

[0002]

2. Description of the Related Art In recent years, with the improvement of road networks, high output and high performance of vehicles, the speeding up of vehicles has been increasing more and more. In particular, not only high speed running, but also turning performance becomes a problem especially in this type of vehicle. That is, whether it is possible to turn at a higher speed or whether it directly affects safety, is the performance of the tire. Generally, measures and improvements proposed for these measures have been to increase the rigidity of the tire by adding a reinforcing layer from the bead base region to the vicinity of the tire maximum width.

[0003]

However, even if the reinforcing layer is added, the turning performance is not improved in spite of the increase in the apparent rigidity, but conversely, the disadvantages in terms of weight, cost, and riding comfort, etc. It was revealed by actual driving that deterioration would occur.

In view of the above facts, it is an object of the present invention to provide a pneumatic radial tire capable of improving riding comfort and high-speed turning performance without increasing weight.

[0005]

According to a first aspect of the present invention, there is provided a tread portion, a pair of bead portions including a bead core, and organic fiber cords arranged substantially at 90 ° with respect to a tire circumferential direction. Air having one or more carcass layers and two or more belt layers disposed in the crown area of the carcass layers and outward in the tire radial direction and intersecting each other at a relatively small angle with respect to the tire circumferential direction. In a radial tire with a filler, the bead core is made of metal 1
The strands are formed by substantially continuous winding, and a JIS hardness of 80 ° to 98 ° is provided in an inner region of the bead core in the tire axial direction.
A bead toe reinforcing rubber stock is arranged, the width of the bead toe reinforcing rubber stock in the tire axial direction is in the range of 0.5 to 2.0 times the width of the bead core, and the bead core extends from the outer end in the tire axial direction. The width in the tire axial direction to the inner end in the tire axial direction of the portion is 1.1 to 3.0 times the width in the tire axial direction of the bead core, and the tire axial side surface region and the radial direction of the bead core and the bead toe reinforcing rubber stock It is characterized in that the inner surface area is integrally reinforced by a chafer made of an organic fiber cord.

A pneumatic radial tire according to a second aspect is the pneumatic radial tire according to the first aspect, characterized in that the bead core has a substantially circular cross section.

A pneumatic radial tire according to a third aspect is the pneumatic radial tire according to the first aspect, characterized in that the bead core has a substantially rectangular cross section.

A pneumatic radial tire according to a fourth aspect is the pneumatic radial tire according to any one of the first to third aspects, further comprising a bead protect that fills a gap between the rim flange and the bead portion. It is characterized by being provided in the bead part.

[0009]

According to the pneumatic radial tire of the present invention, since the bead core is formed by winding one strand of wire, the bead core has low rigidity and a uniform force as compared with the conventional strand bead core. Can bear. For this reason, the fitting property is good when the rim is assembled, uniformity as an assembly is obtained, and there is no local deformation such as large deformation when the vehicle turns, and the force can be applied over a wide range of the tire. Therefore, the change in the ground contact shape (particularly the ground contact pressure) during turning is reduced, and the turning performance is improved. The cross-sectional shape of the bead core may be a substantially circular cross section or a quadrangular cross section.

Further, a toe tip reinforced rubber stock having a JIS hardness of 80 ° to 98 ° is arranged at an optimum position inside the bead core in the radial direction of the tire.
A chafer made of organic fiber cords is provided on the tire axial side surface area and the radial inner surface area of the bead toe reinforced rubber stock, so that the bead collapse during the high speed turning is greatly reduced and the turning performance is improved by the bead core. In addition to that, the turning performance can be further improved,
The synergistic effect of these improves the high-speed turning performance. Moreover, in the pneumatic radial tire of the present invention, since only a part of the rubber in the bead portion has high hardness, the tire weight does not increase.

The hardness of the toe reinforced rubber stock is 8
If it is 0 ° or less, the bead portion base portion is likely to move when the bead portion is largely deformed, and in extreme cases, rim detachment or the like is likely to occur. Further, when the hardness of the toe tip reinforced rubber stock is 98 ° or more, the rigidity of the bead portion is extremely increased, and various problems such as a bead toe chip and a deterioration in fit are caused.
May occur, which is not preferable.

If the width of the toe-tip reinforced rubber stock in the tire axial direction is less than 0.5 times the width of the bead core in the tire axial direction, the effect of suppressing bead disengagement and movement of the bead portion is lost, which is not preferable. If it exceeds 2 times, problems such as rim assembly property and fit property occur, which is not preferable.

Further, when the tire axial width from the tire axial outer end of the bead core to the tire axial inner end is less than 1.1 times the tire axial width of the bead core, It becomes difficult to suppress the movement of the bead portion during large deformation of the portion, which may cause a problem such as rim detachment, which is not preferable, and when it exceeds 3.0 times, problems such as rim assembly property and fit property occur, which is not preferable.

Further, by providing the bead portion with a bead protect that fills the gap between the rim flange and the bead portion, it is possible to further prevent the bead portion from falling axially outward.

[0015]

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

As shown in FIG. 1, the pneumatic radial tire 10 of this embodiment has a pair of bead cores 12 and a toroidal carcass layer 14. The carcass layer 14 is composed of at least one carcass ply 16 in which a large number of cords extending in the radial direction are embedded, and in the present embodiment, the carcass ply 16 has two carcass plies 16.

In this embodiment, the carcass ply 16 has organic fiber cords inclined by 80 ° with respect to the tire circumferential direction, and the cords intersect with each other between adjacent plies. The organic fiber cord of the carcass ply 16 may be inclined at 90 ° with respect to the tire circumferential direction.

The carcass ply 16 extends from one bead core 12 to the other bead core 12,
Body part 1 located inside the tire core axial direction of the bead core 12
6A and a folded-back portion 16B that is folded back to the outside of the tire around the bead core 12 and that is located outside of the bead core 12 in the tire axial direction.

The bead core 12 is a so-called round bead having a round cross section, which is formed by spirally winding one wire element wire (diameter 1.0 mm) around the outer periphery of the core center,
Alternatively, a bead core called monosland (see FIG. 2) in which one wire element wire is sequentially wound from the inside and stacked in a rectangular cross section is preferable, but the cross sectional shape is not limited to these shapes.

The bead core 12 of this embodiment is a round bead formed by winding one wire element wire (diameter 1.0 mm), and has a tire axial width L3 of 8 mm.

On the other hand, a belt layer (not shown) composed of at least two belt plies is arranged on the outer side of the carcass layer 14 in the tire radial direction. The cords of this embodiment are embedded and these cords intersect each other in the adjacent belt plies. Further, at least one belt reinforcing layer (not shown) is provided adjacent to the tire radial direction outer side of at least both width direction areas of the belt layer, and further, a tread (not shown) is provided on the tire radial direction outer side. No) is arranged.

A toe-tip reinforcing rubber stock 18 is arranged inside the bead core 12 in the radial direction of the tire with the carcass ply 16 interposed therebetween. Toe reinforced rubber stock 18
Has a substantially triangular cross section along the tire axis, and the outer circumference is along the tire inner surface of the bead portion 20, the rim side surface, and the carcass ply 16. Here, the hardness of the toe tip reinforced rubber stock 18 is 80 ° to 98 ° in JIS hardness,
It is preferable that the angle is 85 ° to 97 °. The hardness of the toe tip reinforced rubber stock 18 of this embodiment is 9
It is 5 °.

The tire axial width L2 of the toe tip reinforcing rubber stock 18 is 0.5 to 2.0 times, preferably 0.5 to 1.5 times the tire axial width L3 of the bead core 12. .

The dimension H of the toe tip reinforcing rubber stock 18 in the tire radial direction is 10 mm in this embodiment.

Further, the tire axial width L1 from the tire axial outer end of the bead core 12 to the tire axial inner end of the bead portion 20 is the tire axial width L3 of the bead core 12.
It is preferably 1.1 to 3.0 times. In this example, L1 was 1.7 times L3.

Canvas chafers 22 made of organic fiber cords are integrally arranged on the side of the bead core 12 and the toe tip reinforcing rubber stock 18 in the tire axial direction and the inner side of the tire radial direction. This canvas chafer 22 is a general one, and as a molding method, it is preferable to preset the toe-tip reinforced rubber stock 18 in the canvas chafer 22 and integrate it on a molding former for accuracy and productivity. It is preferable above.

Next, the operation of this embodiment will be described. In the pneumatic radial tire 10 of this embodiment, the bead core 12 is used.
However, because it is a so-called round bead whose cross section is rounded by winding one strand of wire, its rigidity (tensile strength is the same) is lower than that of the conventional strand bead core, and the force is evenly distributed. can do. For this reason, the fitting property is good when the rim is assembled, uniformity as an assembly is obtained, and there is no local deformation such as large deformation when the vehicle turns, and the force can be applied over a wide range of the tire. Therefore, the change in the ground contact shape (particularly the ground contact pressure) during turning is reduced, and the turning performance is improved.

Further, since a tough tip-reinforced rubber stock 18 of high hardness is arranged on the inner side in the radial direction of the tire with the carcass ply 16 of the bead core 12 interposed therebetween, and a canvas chafer 22 is further provided, during high speed turning. The fall of the bead portion 20 is significantly reduced, and in addition to the effect of improving the turning performance by the bead core 12, the turning performance can be further improved. Moreover, in the pneumatic radial tire 10 of the present embodiment, the tire weight does not increase because only a part of the rubber in the bead portion 20 has a high hardness.

If the hardness of the toe tip reinforcing rubber stock 18 is 80 ° or less, the base portion 20A of the bead portion 20 is likely to move when the bead portion 20 is largely deformed, and in extreme cases, the rim may be easily dislocated. Further, when the hardness of the toe tip reinforcing rubber stock 18 is 98 ° or more, the rigidity of the bead portion 20 is extremely increased, and various problems such as bead toe chipping and deterioration of fitting property may occur, which is preferable. Absent.

The tire axial width L2 of the toe tip reinforcing rubber stock 18 is the tire axial width L of the bead core 12.
If it is less than 0.5 times, it is not preferable because the effect of bead disengagement and the movement of the bead portion 20 is lost, and if it exceeds 2.0 times, problems such as rim assembly property and fit property occur, which is not preferable.

Further, when the distance L1 from the tire axially outer end of the bead core 12 to the tire axially inner end of the bead portion 12 is less than 1.1 times the tire axial width L3 of the bead core 12, the bead portion 20 is formed. It becomes difficult to suppress the movement of the bead portion at the time of large deformation, which may cause a problem such as rim detachment, and it is not preferable when it exceeds 3.0 times, because problems such as rim assembly property and fit property occur.

[Test Example] The pneumatic radial tire according to the present example, the conventional pneumatic radial tire, and the pneumatic radial tire according to the comparative example were mounted on an actual vehicle, and a riding comfort test and a turning performance test were performed.

Here, in the pneumatic radial tire of the conventional example, the bead core is a quadrangular strand bead core, two reinforcing layers are provided around the bead core, and no toe tip reinforcing rubber stock is provided. . Further, in the pneumatic radial tire of the comparative example, the bead core has the same structure as that of the present invention, but the toe tip reinforcing rubber stock is not provided.

The riding comfort test was evaluated by the running feeling by running on a test course with a circumference of 6 km, and the turning performance test was evaluated by the lap time when the vehicle was run on the test course. The test results are shown in Table 1 below, and the index display is based on the conventional example being 100. Here, the larger the value, the better the performance.

[0035]

[Table 1]

From the test results shown in Table 1 above, it is clear that the pneumatic radial tire to which the present invention is applied has improved riding comfort and turning performance as compared with the conventional tire and the comparative tire. is there.

As shown in FIG. 3, the bead protector 24 is provided on the bead portion 20 of the pneumatic radial tire 10.
May be provided.

The bead protect 24 has a substantially triangular cross section, and the pneumatic radial tire 10 is attached to the rim 2.
When assembled to 8, the rim flange 28A and the bead portion 2
A gap portion having a substantially triangular cross section with 0 is filled. The distance t between the bead protect 24 and the rim flange 28A is preferably about 0 mm (close contact state) to 5 mm. The shape on the rim flange 28A side preferably has a smooth curvature along the rim flange 28A as shown in the figure.

The bead protect 24 can be formed by adhering a long raw rubber member having a substantially triangular cross section at a predetermined position of the bead portion 20 when molding a green tire.

The hardness of the rubber of the bead protect 24 after vulcanization is preferably higher than the hardness of the rubber of the bead portion 20.

It should be noted that it is preferable to provide an annular rim line 26 in which the rubber of the bead portion 20 is protruded, on the outer side in the tire radial direction of the bead protect 24 on the outer side in the tire radial direction (arrow A side). That is, in order to provide the rim line 26, a recess (not shown) having a shape opposite to the rim line 26 is formed on the inner surface of the mold, and the recess in the mold serves as an escape area for air in the mold during vulcanization molding. By acting, the air pocket can be smoothly removed, the rubber flow in the mold can be improved, and defects such as bare can be prevented. Two or more rim lines 26 can be provided if necessary.

In the pneumatic radial tire 10 provided with the bead protect 24, the substantially triangular clearance between the bead portion 20 and the rim flange 28A is substantially filled with the bead protect 24, so that the bead protect 24 is used during high-speed turning. It is possible to further reduce the collapse of the bead portion 20, and it is possible to further improve the turning performance of the vehicle. Since the substantially triangular clearance between the bead portion 20 and the rim flange 28A is not so large actually, the amount of rubber used in the bead protect 24 is small and the increase in weight can be substantially ignored. It is a value.

The bead protect 24 is not limited to the pneumatic radial tire 10 having round beads, but a bead core having another cross-sectional shape, for example, a bead core 12 having a square cross-section as shown in FIG. 4 (one wire). A pneumatic radial tire 1 having a bead core called a monosland, which is obtained by sequentially winding wires from the inside and stacking them in a rectangular cross section.
Of course, it may be provided at 0.

[0044]

As described above, since the pneumatic radial tire of the present invention has the above-mentioned structure, it has an excellent effect that the riding comfort and the high-speed turning performance can be improved without increasing the weight.

[Brief description of drawings]

FIG. 1 is a sectional view of essential parts of a pneumatic radial tire according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of essential parts of a pneumatic radial tire according to another embodiment of the present invention.

FIG. 3 is a cross-sectional view of essential parts of a pneumatic radial tire according to another embodiment of the present invention provided with a bead protector.

FIG. 4 is a cross-sectional view of essential parts of a pneumatic radial tire according to still another embodiment of the present invention provided with bead protection.

[Explanation of symbols]

 10 Pneumatic radial tire 12 Bead core 14 Carcass layer 18 Bead toe reinforcing rubber stock 20 Bead part 22 Canvas chafer 24 Bead protect

Claims (4)

[Claims] 1. A tread portion, a pair of bead portions including a bead core, one or more carcass layers made of organic fiber cords arranged at substantially 90 ° with respect to a tire circumferential direction, and a crown of the carcass layer. A pneumatic radial tire having two or more belt layers disposed in a region and outward in the tire radial direction and intersecting each other at a relatively small angle with respect to the tire circumferential direction, wherein the bead core is made of metal. And a bead toe reinforcing rubber stock having a JIS hardness of 80 ° to 98 ° is arranged in an inner region of the bead core in the tire axial direction. The width is in the range of 0.5 to 2.0 times the width of the bead core, and is within the tire axial direction of the bead portion from the tire axial outer end of the bead core. The tire axial width up to one end is 1.1 to 3.0 times the tire axial width of the bead core, and the tire axial side surface area and the radial inner surface area of the bead core and the bead toe reinforcing rubber stock are organic fiber cords. Pneumatic radial tire characterized by being integrally reinforced by a chafer. 2. The pneumatic radial tire according to claim 1, wherein the bead core has a substantially circular cross section. 3. The pneumatic radial tire according to claim 1, wherein the bead core has a substantially rectangular cross section. 4. The pneumatic radial tire according to claim 1, wherein a bead protect is provided in the bead portion to fill a gap between a rim flange and the bead portion. .