JPH08310206A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE: To enhance steering stability during high speed traveling by restricting of the upper and lower ends of the reinforcing layer measured from the base line of the sectional plan within a prescribed range of a height in the sectional plan of the tire with an additional reinforcing layer, which is arranged with a shallow fiber-cord-angle measured from the circumferential direction, to the outside in the axial direction of a radial carcass tire. CONSTITUTION: In a tire 1, a pair of side walls 2 are connected with a tread part 3, which extends over the side walls 2, inn a toroidal form. There side walls 2 and tread part 3 are reinforced by a radial carcass 4, or a fiber cord, while an inextensional belt layer 5 is arranged for reinforcement in the carcass 4 and at the position corresponding to the tread part 3. In addition, an additional reinforcing layer 6 made of a fiber cord is provided to the outside in the axial direction of the carcass 4 and in the range corresponding to the area of the side wall 2. In the additional reinforcing layer 6, the height of the upper end 7 and the lower end 8 from the tire base line (X) lie between ha , which is 55 to 75% of the height(H) from the base line in the sectional plan of the tire, and hb , which is 20 to 30%, and moreover layer 6 is arranged in such a manner that the cord angle from the circumferential direction is shallow.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel-efficient pneumatic radial tire having excellent maneuverability.

[0002]

2. Description of the Related Art In recent years, the reduction of fuel consumption has been a problem for automobiles, which are convenient as a means of transportation, due to problems such as depletion of limited petroleum resources and global warming due to carbon dioxide emissions. -The tires used for these tires have been improved, and the development of fuel-efficient tires with low rolling resistance is urgently needed. In order to reduce rolling resistance, especially in the case of passenger car tires, while having a lightweight and simplified radial structure, in order to suppress flexural deformation, around 3 Kgf / Cm ² ,
A very high internal pressure is applied to this type of tire.

[0003]

Such a tire is related to steering stability, and the required lateral rigidity is improved by applying a high internal pressure, but the circumferential rigidity is not increased, so that the tire is traveling at a particularly high speed. At that time, the steering stability at the small steering angle deteriorates,
Often a problem. The present invention has been made in view of the above problems, and an object of the present invention is to provide a pneumatic radial tire excellent in steering stability while maintaining low fuel consumption.

[0004]

According to the present invention, a pair of side walls and a tread portion straddling both side walls are connected in a toroidal shape, and these portions are reinforced by a radial cord of a fiber cord. , At the position of the tread portion on the circumference of this carcass, while arranging a non-stretchable belt layer for reinforcement,
A tire is provided with an additional reinforcing layer of a fiber cord on the outside of the carcass in the side wall area in the axial direction, and the upper end and the lower end of the additional reinforcing layer have a base line on the tire cross section. 55-75% of each tire cross-section height
And in the range of 20 to 30%, and
It is a pneumatic radial tire characterized by having a shallow angle arrangement of the wheels.

The code of the additional reinforcing layer is 25 in the circumferential direction.
An angle range of up to 45 ° is preferable, and the center of the additional reinforcing layer is preferably arranged so as to be eccentrically located radially outward from the center of the tire cross-section height.

[0006]

The tire according to the present invention has an additional reinforcing layer, in which fiber cords are arranged at a shallow angle with respect to the circumferential direction, on the outer side of the radial arcus in the sidewall region in the axial direction. Since the height above the base line on the section is limited to 55 to 75% and 20 to 30% of the tire section height, respectively, the arrangement code that is shallowly inclined in the circumferential direction and the radial By cooperating with the reinforcing cord of the oriented carcass, the circumferential shear rigidity is effectively increased, thereby advantageously improving the steering stability during high speed running, while The undesired increase in the longitudinal spring (radial rigidity) of the tire caused by the arrangement angle is suppressed, so that even if a high internal pressure is applied and used, the riding comfort is substantially deteriorated due to the tire structure. Absent.

The width of the additional reinforcing layer is equivalent to 25 to 55% of the tire cross-sectional height based on the above-mentioned numerical values as the arrangement position, and this range maintains the light weight for low fuel consumption and the circumferential shear rigidity. This is the width required for improvement. Positionally, when the height of the upper end exceeds 75% of the tire cross-section height, the longitudinal spring of the tire rises too much, while when the lower end height is less than 30%, the required circumferential shear rigidity is required. Can't get

In view of the operation described above, the core of the additional reinforcing layer is
The arrangement angle of the cords with respect to the circumferential direction is preferably 25 to 45 °, and the center of the additional reinforcing layer is preferably unevenly distributed slightly outward in the radial direction from the center of the tire cross-section height.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A description will be given below with reference to the drawings. FIG. 1 is a sectional view of a tire showing an embodiment of the present invention. In the tire 1 of the present invention, a pair of side walls 2 and a tread portion 3 extending over both side walls are connected in a toroidal shape, and the side wall 2 and the tread portion 3 are connected to a radial cord 4 of a fiber cord. The non-stretchable belt layer 5 is arranged at the position of the tread portion 3 on the circumference of the carcass 4 to reinforce the carcass 4, and at the same time, in the axial direction outside the carcass 4 in the side wall 2 area, the fibers are It has an additional reinforced layer 6 of code. And this additional reinforcing layer 6, the position of the upper end 7 and lower 8, on the tire section base - each from 55 to 75% of Surain X the tire section height H, and 20-30% of the range of the height h _a , H _b , and a shallow angular array of codes with respect to the circumferential direction. In Fig. 1, the right half of the tire 1 from the equatorial plane O is omitted, but it is symmetrical.

FIG. 1 shows an example of a tire for a passenger car of 185 / 65R14 size, in which a carcass 4 is 1500d / 2 polyester core.
One of the plies that are arranged in the direction orthogonal to the equatorial plane O,
Further, as the belt layer 5, two layers of steel cords having a twist structure of 1 × 5 arranged at an angle of 20 ° with respect to the equatorial plane O were laminated so that these cords intersect each other. It is a structure.

Next, as the additional reinforcing layer 6, one rubberized layer in which 840d / 2 nylon cords were arranged at an angle of 35 ° with respect to the circumferential direction was fixed to the outer surface of the carcass 4 in the axial direction. And in this case, the heights h _a and h _b of the upper end 7 and the lower end 8 of the reinforcement layer 6 are
The tires were provided at positions of 65% and 25% of the sectional height H (the width of the reinforcing layer 6 is 40% of the sectional height H).

A hard rubber filler (shore A hardness 90 °) 11 is provided between the carcass 4 and the end 10 of the carcass ply wound around the bead ring 9 to form a base line X.
It was tapered to a height j of 18%. The cross-sectional area of the rubber filler-11 is 0.45 Cm ² . And again, on the radially inner end of the side wall 2, that is, on the back surface of the bead,
Place a hard rubber chafer (Shore A hardness 75 °) 12 from the base position of the bead to the cross section height H from the base line X.
Placed over a height i of 35% of. Rubber chafer 12
Has a cross-sectional area of 1.25 Cm ² . The above-mentioned height j and cross-sectional area of the hard rubber filler 11 are 13 to 23% and 0.3 to 0.6 Cm, respectively.
² , and the above-mentioned height i and cross-sectional area of the rubber chafer 12 are
The ranges of 30-40% and 1.1-1.4 Cm ² , respectively are preferred.

[0013]

[Effect] In order to confirm the effect of the tire according to the present invention, rolling in a room is performed between the tire of the example described with reference to FIG. 1 and the tire of the comparative example which is different only in that an additional reinforcing layer is not used. Driver measurement of resistance and driving stability and riding comfort during high-speed running lane change with an actual vehicle
It was evaluated by the filling method.

In the test, the tire was assembled on a 14 × 5 1 / 2J rim, the internal pressure of 3.0 Kgf / Cm ² was filled, and the rolling resistance was 47.
A load of 5 Kgf was applied, and the actual vehicle test was performed on the asphalt pavement circuit in the speed range of 80 to 120 Km / H.
The test results are shown in Table 1.

[0015]

[Table 1]

As described above, the additional reinforcing layer in which the fiber cords are arranged at a shallow angle with respect to the circumferential direction is provided at the upper end on the axially outer side of the fiber cord cord carcass in the sidewall region of the radial tire. And the height above the base line on the tire cross section at the lower end position is 55 to 75 of the tire cross section height, respectively.
% And 20 to 30%, it is possible to advantageously improve the driving stability as shown by the comparative example + 3 points while maintaining low fuel consumption and riding comfort. is there.

[Brief description of drawings]

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

[Explanation of symbols]

 1 Tire 2 Sidewall 3 Tread 4 Carcass 5 Belt layer 6 Additional reinforcing layer 7 Upper end of additional reinforcing layer 8 Lower end of additional reinforcing layer X Base line on tire cross section

Claims (3)

[Claims] 1. A pair of side walls and both side walls.
The tread portion straddling the rope is continuous in a toroidal shape, and these portions are reinforced by the radial cord of the fiber cord, and the non-stretchable belt layer is arranged at the position of the tread portion on the circumference of the carcass. A tire having an additional reinforcing layer of a fiber cord on the outer side in the axial direction of the carcass in the side wall area, which is reinforced, and the upper and lower end positions of the additional reinforcing layer are on the tire cross section. Pneumatic radial tires having a tire cross-section height in the range of 55 to 75% and 20 to 30% from the base line, respectively, and having a shallow angle arrangement of the cord with respect to the circumferential direction. 2. The code of the additional reinforcing layer is in the circumferential direction.
The pneumatic radial tire according to claim 1, wherein the pneumatic radial tire has an angle of 25 to 45 °. 3. The pneumatic radial tire according to claim 1, wherein the center of the additional reinforcing layer is unevenly distributed outward in the radial direction from the center of the tire cross-section height.