JP3472778B2 - Pneumatic tire - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire and is used for a radial tire for passenger cars having a flatness of 55% or less.

[0002]

2. Description of the Related Art In recent years, as the performance of passenger cars has improved, flat tires excellent in steering stability, grip performance and durability at high speed have been particularly used in sports cars. Japanese Patent Laid-Open No. Hei 4
It is proposed in Japanese Patent Publication No. -95512 and the like.

[0003]

In response to the steering wheel operation in tire behavior, the rigidity of the sidewall portion must be increased in order to improve the initial response, while the rigidity of the sidewall portion is increased. Raising the angle makes it easier to lose the sticky feeling (ground contact) at the large steering angle. On the contrary, if the rigidity of the sidewall portion is weakened, the stickiness at a large steering angle can be obtained, but the initial responsiveness at a small steering angle tends to deteriorate.

That is, the initial response performance and the grounding property at a large steering angle are in a trade-off relationship, and one of them has been sacrificed in the past. Therefore, an object of the present invention is to provide a pneumatic tire capable of satisfying a trade-off relationship by modifying the arrangement conditions of the members that reinforce the sidewall portion.

[0005]

SUMMARY OF THE INVENTION The present invention is directed to a tread portion 1
Carcass 5 integrally provided with a winding portion 4 for winding the bead core 3 from the inner side to the outer side in the tire axial direction on a toroidal main body portion extending from the side wall portion 2 to the pair of bead cores 3, and the main body portion and the winding portion 4. And a tapered bead filler 6 extending radially outward from the bead core 3, a breaker layer 7 disposed inside the tread portion 1 and radially outside the carcass 5, the bead core 3 and A first reinforcing layer 8 using an aromatic polyamide cord surrounded by the carcass 5 while winding a bead filler 6 from the inner side to the outer side in the tire axial direction, and a winding portion of the first reinforcing layer 8 and the carcass. A second reinforcing layer 9 using a steel cord interposed between the pneumatic tire and
In order to achieve the above-mentioned object, the following technical measures are taken, that is, in the present invention, the radial length to the breaker layer 7 is A with the outer side in the radial direction of the bead core 3 as a reference, and the carcass is The length of the winding portion 4 of 5 is B,
When the radial length of the first reinforcing layer 8 is C, the radial length of the second reinforcing layer 9 is D, and the radial length of the bead filler 6 is E, C / A is 60 to 75%. , D / A is 40 to 55%, E / A is 20 to 30%, C-D is 12 to 20 mm, and D-E is 15 to 2
It is characterized by being set to 0 mm.

When the pneumatic tire having the above-mentioned structure is mounted on a passenger car (including sports type) for traveling, the rigidity of the sidewall portion 3 is optimized so that both the initial response performance and the ground contact performance at a large steering angle are achieved. Can be done. Where C-
If D is set to 12 mm or less and D-E is set to 15 mm or less, the flow of the force lines becomes unnatural and the rigidity of the sidewall portion 2 changes abruptly, and the linearity in the relationship of cornering force generation with slip angle is lost. It also deteriorates the grounding property of the large steering angle.

On the other hand, both CD and DE are 20 m
If it is m or more, the rigidity of the sidewall portion 3 is lowered and the initial responsiveness becomes dull. C / A is around 67%, D / A is 4
It is desirable to set around 7% and E / A around 25%,
Here, “front and rear” means about ± 1% depending on the size of the tire. On the other hand, C-D and D-E are both 17 mm
It is desirable to be the front and back, and the front and back here means about ± 1 mm, although it depends on the size of the tire.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the pneumatic tire according to the present invention will be described below with reference to the drawings. FIG. 1 shows the right half of a radial tire for passenger cars having an aspect ratio of 55% or less, and is symmetrical about a meridian 0-0. In the tire T according to the present invention, a winding portion 4 for winding the bead core 3 from the inner side in the tire axial direction to the outer side is integrally provided on a toroidal main body portion extending from the tread portion 1 to the pair of bead cores 3 through the sidewall portion 2. A carcass 5, a tapered bead filler 6 disposed between the main body portion and the winding portion 4 and extending radially outward from the bead core 3,
The breaker layer 7 arranged inside the tread portion 1 and outside the carcass 5 in the radial direction, the bead core 3 and the bead filler 6 are wound up from the inner side to the outer side in the tire axial direction and are surrounded by the carcass 5. A first reinforcing layer 8 using an aromatic polyamide cord, and a second reinforcing layer 9 using a steel cord interposed between the first reinforcing layer 8 and the carcass winding portion 4. I have it.

Further, in the present invention, the radial length up to the breaker layer 7 is A, the length of the winding portion 4 of the carcass 5 is B, and the first reinforcing layer is the radial outside of the bead core 3 as a reference. 8 is C, the second reinforcing layer 9 is D, and the bead filler 6 is E.
, C / A is 60 to 75% and D / A is 4
0-55%, E / A is 20-30%, C-D is 12-20 mm, D-E is 15-2.
It is set to 0 mm.

In the above construction, the carcass 5 is composed of one or two plies in which radial cords are arranged in parallel, and as the cords, organic fibers such as nylon and polyester, metal, carbon fibers or the like is used. it can.
The bead filler 6 can be made of hard rubber having a JIS A hardness of 60 to 90 and has a tapered cross section or a wedge shape.

Further, the breaker layer 7 has its cords arranged in parallel at an angle of 10 to 30 degrees with respect to the circumferential direction of the tire. In the illustrated example, it consists of two inner and outer plies, and the cords of each ply cross each other. It is desirable to do. The breaker layer 7 may be made of steel, but aromatic polyamide is preferable for weight reduction.

Further, the reason why the first reinforcing layer 8 and the second reinforcing layer 9 are separately used for aramid and steel is to make the initial response sharp and both layers 8 and 9 are made of aramid. This is because the initial responsiveness becomes dull.
Further, the first reinforcing layer 8 has a J-shaped cross section and is rolled up on the bead core 3 to improve rigidity and response, while the second reinforcing layer 9 is made of steel without being rolled up. This is because it is difficult to get involved and becomes a neck in manufacturing.

C / A is around 67%, D / A is 47%
Before and after, E / A is desirable around 25%, C-D and D
-E is most advantageous around 17 mm. Next, TL24
Examples 1, 2, 3 of 5/45 ZR17 pneumatic tire
The data of Comparative Examples 4, 5 and 6 are shown in Table 1 below.

[0014]

[Table 1]

As is clear from Table 1 above, Comparative Example 4
On the other hand, in the embodiments of the present invention, the initial responsiveness and the grounding property can be compatible with each other. Especially C / A 67%, D / A
Around 47%, E / A around 25%, C-D and D-
It is advantageous if E is around 17 mm.

[0016]

As described in detail above, according to the present invention, both initial responsiveness and grounding property at the time of large steering angle can be achieved, and the means for achieving the same is not increased or decreased in the number of members, and therefore the manufacture is easy.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a right half portion of a tire according to the present invention.

[Explanation of symbols]

1 tread section 2 sidewalls 3 bead core 4 winding section 5 carcass 6 bead filler 7 breaker layers 8 First reinforcement layer 9 Second reinforcement layer

Claims (3)

(57) [Claims] 1. A hoisting portion for hoisting a bead core (3) from an inner side to an outer side in a tire axial direction on a toroidal main body portion extending from a tread portion (1) to a pair of bead cores (3) via a sidewall portion (2). 4) a carcass (5) integrally provided, a bead filler (6) having a tapered shape extending radially outward from the bead core (3) arranged between the main body part and the winding part (4), and the tread. The breaker layer (7), which is arranged inside the portion (1) and outside in the radial direction of the carcass (5), the bead core (3) and the bead filler (6) are wound from the inner side to the outer side in the tire axial direction. And a first reinforcing layer (8) using an aromatic polyamide cord surrounded by the carcass (5)
And a second reinforcing layer (9) using a steel cord interposed between the first reinforcing layer (8) and the carcass winding portion (4), Based on the outside in the radial direction of the bead core (3), the radial length to the breaker layer (7) is (A), the length of the winding portion (4) of the carcass (5) is (B), 1
When the radial length of the reinforcing layer (8) is (C), the radial length of the second reinforcing layer (9) is (D), and the radial length of the bead filler (6) is (E), C / A is 60 ~
75%, D / A is 40 to 55%, E / A is 20 to 30%, C-D is 12 to 20 mm, and DE is 15 to 20 mm. A pneumatic tire characterized by the following. 2. C / A is around 67% and D / A is 47%.
Before and after, E / A is around 25%, and C-D and D-
The pneumatic tire according to claim 1, wherein each E is about 17 mm. 3. The pneumatic tire according to claim 1, which is a radial tire for passenger cars having a flatness of 55% or less.