JPH0924711A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve operation stability while securing high durability as well as restraining an increase of a tire cost and weight. SOLUTION: A pneumatic radial tire is composed of a bead part 1 and a side wall part 2, a tread part 3 extending in the toroidal shape, at least a sheet of radial carcass ply 5 extending between a pair of bead cores imbedded in the bead part 1, and a belt 6 equipped with at least a layer of a belt layer 6a imbedded on an outer periphery of a crown part of the radial carcass ply 5. A reinforcement layer 9, comprising organic monofilament codes whose total number of deniers is 1000-5000 deniers, is provided between bead filler 8 arranged at the outer periphery side of the bead core 4 and a body part 5a of the radial carcass ply 5 within a range of 10-70% of a height of the radial direction of a side part, and also a tilt angle of the organic monofilament codes is made to be 10-50 degrees.

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 radial tire for passenger cars, which suppresses an increase in tire weight and, in turn, rolling resistance as much as possible, while ensuring high durability and excellent steering performance. It achieves stability.

[0002]

2. Description of the Related Art As a conventional technique for improving the steering stability of a pneumatic radial tire for passenger cars, a portion from a bead portion to a sidewall portion is reinforced with a reinforcing layer made of steel cord or organic fiber cord. hand,
Some increase the rigidity of the tire.

[0003]

However, in the prior art in which steel cords are used for reinforcement, the rigidity of the tire can be increased as expected, but the cost and weight of the tire increase significantly, Therefore, there is a problem that the rolling resistance also becomes large, and in the conventional technology in which the organic fiber cord is reinforced, the increase in the cost and the weight of the tire can be suppressed. Although the increase may be suppressed, there, in the vicinity of the bead portion during load rolling of the tire, of the organic fiber cord, in consideration of fatigue due to compressive deformation,
Since the cord is a multi-filament cord and the twisting coefficient NT of the multi-filament cord is approximately 0.7, the cord modulus is greatly reduced, contributing to the steering stability. There was another problem of being low.

[Equation 1]

The present invention has been made as a result of studies for solving such problems of the prior art, and an object of the present invention is to suppress an increase in cost and weight of a tire and to increase the tire cost. (EN) It is possible to provide a pneumatic radial tire capable of effectively improving driving stability while ensuring durability.

[0005]

The present invention can effectively suppress an increase in tire weight by using an organic fiber cord as a reinforcing layer cord, and, of course,
The organic fiber cord is a monofilament that is inferior in fatigue resistance to compressive strain as compared with the multifilament cord, and the cord modulus is increased as expected, and the bead is selected by selecting the arrangement position of the monofilament cord. It was made based on the finding that the risk of fatigue fracture of the monofilament cord can be sufficiently removed due to the compressive deformation in the vicinity of the portion, and the pneumatic radial tire of the present invention is Radial heights (hereinafter simply referred to as "side radial heights") 10 to 7 from the bead portion to the radial outer peripheral edge position of the bead core to the radial inner peripheral edge position of the belt.
Within the range of 0%, at least one layer of a reinforcing layer composed of an organic monofilament cord such as polyester, nylon, vinylon, aromatic polyamide, etc. is arranged inside the tire along the radial carcass from the bead filler arranged on the outer peripheral side of the bead core. The total number of denier of the organic monofilament cord was set to 1000 to 5000 denier, and the virtual monoline was drawn at the intersection of the organic monofilament cord and the virtual circle concentric with the tire center. The angle between the tangent line and the organic monofilament cord (hereinafter simply referred to as "tilt angle") is in the range of 10 to 50 °.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention is illustrated in FIG. In the figure, 1 is a bead part, 2 is
A sidewall portion continuous with the bead portion 1 and a tread portion 3 extending in a toroidal shape between the sidewall portions are shown.

Here, each of these parts is reinforced by two radial carcass plies 5 made of polyester cord, which extend between a pair of bead cores 4 arranged in the bead part 1, and both of these carcass plies 5 are reinforced. Both side end portions are wound up from the inside to the outside of the bead core 4. Further, on the outer peripheral side of the crown portion of these carcass plies 5, a belt 6 formed of two belt layers 6a made of steel cord is arranged to reinforce the tread portion 3 and further It is arranged on the outer peripheral side,
The tread portion 3 is also reinforced by a single belt reinforcing layer 7 made of a nylon cord extending substantially in the red circumferential direction. In the figure, 8 is the outer peripheral side of the bead core 4, and the main body portion 5a of the carcass ply 5 and the winding end portion 5 thereof.
The bead filler arrange | positioned between b is shown.

Here, in this example, the total number of denier is 100.
Reinforcing layer 9 consisting of an organic monofilament cord in the range of 0 to 5000, more preferably 2000 to 3000 denier, for example a polyester monofilament cord.
The bead filler 8 and the body portion 5 of the carcass ply 5
a, the inner end in the radial direction of the organic monofilament cord, and by extension, the reinforcing layer 9, is disposed along the body portion 5a between the bead portion 1, more specifically, the bead core 4 and the vicinity thereof. And a region h of the reinforcing layer 9 extending outward in the radial direction is set to a range of 10 to 70, preferably 30 to 50% of the height H of the side portion in the radial direction. Here, the organic monofilament cord has a tilt angle of 10 to 50, more preferably 30 to 45 °.

According to the pneumatic radial tire constructed as described above, by using the organic fiber cord as the reinforcing layer cord, both the tire cost and the weight are reduced as compared with the case of using the steel cord, as described above. In addition, by using monofilament as the organic fiber cord, the cord modulus can be effectively increased compared to the case where multifilament is used, and steering stability is comparable to steel cord. Can be improved.

Further, here, since the organic monofilament cord reinforcing layer 9 is arranged along the bead filler 8 and the radial carcass main body portion 5a along with it, the portion in the vicinity of the bead portion when the tire rolls is loaded. Is bent and deformed to the rim flange side, the organic monofilament cord will be located outside the bend from the neutral axis of bending, and will be subjected to tensile deformation rather than compression deformation. Thus, it is possible to effectively eliminate the risk of fatigue fracture due to compressive deformation, and sufficiently secure the excellent durability of the tire.

Moreover, here, the extending region h of the organic monofilament cord reinforcing layer 9 from the position in the vicinity of the bead core to the outside in the radial direction is set to 10 to 7 at the height H in the radial direction of the side portion.
Within the range of 0%, the rigidity of the tire can be effectively increased while maintaining the excellent durability of the cord itself, and by extension, the tire. That is, it is 1
If it is less than 0%, the tire rigidity cannot be sufficiently enhanced, and if it exceeds 70%, other regions that allow deformation are smaller than the extending region of the organic monofilament cord reinforcing layer 9 having high rigidity. During load rolling of the tire, the deformation of the portion adjacent to the extending region of the reinforcing layer 9 becomes local and the strain increases, so that it becomes difficult to secure excellent durability.

Further, by setting the inclination angle of the organic monofilament cord within the range of 10 to 50 °,
This also ensures excellent durability and can increase the tire rigidity particularly effectively. In other words, if it is less than 10 °, the rigidity cannot be sufficiently enhanced, while if it exceeds 50 °, it is inevitable that both the tire rigidity and the durability are deteriorated.

In addition, in this tire, by setting the denier number of the organic monofilament cord to be 1000 to 5000 denier, high rigidity can be secured and an increase in tire weight can be effectively prevented. That is,
If it is less than 1000 denier, it is difficult to sufficiently enhance the rigidity of the portion where the organic monofilament cord is arranged, and by extension, the rigidity of the tire, and if it exceeds 5000 denier, the thickness of the cord reinforcing layer 9 becomes thick. However, the tire weight becomes too large due to the increase in the rubber thickness from the tread portion to the sidewall portion of the tire.

Thus, here, based on the action of the reinforcing layer 9 made of the organic monofilament cord, the cost and weight of the tire are effectively suppressed, and the organic monofilament cord is not compressed and deformed.
In other words, the steering stability can be increased to almost the same level as in the case of using the steel cord reinforcing layer without fear of fatigue fracture of the monofilament cord.

As shown in the drawing, the carcass ply 5 and at least one of the belt layers 6a may be one, and the belt reinforcing layer 7 may be omitted.
The radial outer end position of the winding end portion 5b of the carcass ply 5 can be changed as required.

FIG. 2 is a vertical cross-sectional view of a main part illustrating another embodiment, which is an organic monofilament cord reinforcing layer 9
Is disposed inside the tire from the bead filler 8 between the inner liner 10 as a lining layer having low air permeability and the main body portion 5a of the radial carcass ply 5 along the main body portion 5a. The other points are the same as those described above. In the embodiment shown in FIG. 3, the organic monofilament cord reinforcing layer 9 is arranged inside the tire from the bead filler 8 and between the main body portions of the two radial carcass plies 5 along the main body portions 5a. It was set up.

Any of these embodiments can bring about the same effects as those described above with respect to the tire cost, weight, durability and steering stability.

[0018]

EXAMPLE A tire having the respective structures shown in FIGS. 1, 2 and 3, and as shown in FIG. 4, an organic monofilament cord reinforcing layer 9 is provided outside the bead filler 8 on the outside of the tire, and the bead filler 8 and the carcass ply 5 are provided. In each of the tires arranged between the winding end portion 5b and the winding end portion 5b, the tire size is 205 / 65R15, the carcass ply cord is a 1000d / 2 double twist polyester cord, and the belt layer cord constitution is 1 ×.
5 steel cords and 1 belt reinforcement layer cord
In the case of a 260d / 2 double-stranded nylon cord, the invention in which the material of the side reinforcing layer cord, the total number of denier, the twist coefficient, the inclination angle, the range of the reinforcing layer, and the like are set as shown in Table 1 Tires 1-6 and comparative tires 1-
When a comparative test of tire weight, steering stability and tire durability was conducted for each of No. 9, the results are shown in Table 2.

Here, the steering stability of the tire is determined by the load specified by JATMA (internal pressure: 2.0 kg / c).
m ² ), the tire contact surface is moved by ± 10 mm in the front-rear direction and in the left-right direction, and is evaluated by performing a so-called tire stiffness test, which measures the ratio of force to displacement amount, and Tire durability is determined by running a drum endurance test under a prescribed internal pressure with a load of 150% of the JATMA standard load, and determining the running distance until failure due to cord breakage or separation at the end of the reinforcing layer. It was evaluated by measuring.

By the way, in Table 2, both steering stability and tire durability are shown as index values using the comparative tire 3 as a control. Here, the larger the index value, the better the result.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

As is clear from the results of the above comparative test, according to the present invention, the tire cost is reduced, the increase of the tire weight is effectively suppressed, and the organic monofilament cord has excellent durability. It is possible to effectively improve the steering stability even after it is exhibited.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an essential part illustrating an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of an essential part illustrating another embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of a main part illustrating still another embodiment.

FIG. 4 is a longitudinal sectional view of a main part illustrating a comparative tire.

[Explanation of symbols] 1 bead portion 2 sidewall portion 3 tread portion 4 bead core 5 radial carcass ply 5a main body portion 5b winding end portion 6 belt 6a belt layer 8 bead filler 9 organic monofilament cord reinforcing layer H side portion radial height h extension Territory

Claims (1)

[Claims] 1. A bead portion and a sidewall portion which are paired together, a tread portion extending in a toroidal shape between both sidewall portions, and at least one sheet extending between a pair of bead cores embedded in the bead portion. In a pneumatic radial tire comprising a radial carcass ply and a belt composed of at least one belt layer disposed on the outer peripheral side of the crown portion of the radial carcass ply, in the radial direction of the belt from the outer peripheral edge position of the bead core Within the range of 10 to 70% of the radial height to the inner peripheral position, a reinforcing layer made of organic monofilament cord is arranged along the radial carcass ply inside the tire from the bead filler arranged on the outer peripheral side of the bead core. The total denier of the organic monofilament cord is 1000-
In addition to 5,000 denier, the angle between the organic monofilament cord and the tangent line drawn to the virtual circumferential line at the intersection of the organic monofilament cord and the virtual circumferential line concentric with the tire center is within the range of 10 to 50 °. Pneumatic radial tire.