JPH06143949A - Pneumatic radial tire for passenger car - Google Patents

Abstract

PURPOSE:To provide a pneumatic radial tire for a passenger car which can improve controllability without damaging high speed durability. CONSTITUTION:While both ends of an inside carcass layer 6 are folded back around a bead core 4 from the inside to the outside of a tire to envelope a bead filler 5, both ends of an outside carcass layer 7 are wound down along the outside of a folded-back part 6a of the inside carcass layer 6. A reinforcing layer 10 consisting of fiber cords is inserted between the inside surface of the bead filler 5 and the inside carcass layer 6, and a reinforcing layer 11 consisting of steel cords is inserted between the folded-bak part 6a of the inside carcass layer 6 and the outside carcass layer 7.

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 for a passenger vehicle, which is capable of improving steering stability without impairing high-speed durability.

[0002]

2. Description of the Related Art Generally, in order to improve the steering stability of a pneumatic radial tire for a high-performance passenger vehicle, a reinforcing layer made of a steel cord or an organic fiber cord is inserted into a bead portion. However, since the driving performance of passenger cars (especially high-powered cars called sports cars) in recent years has been remarkably improved, conventional tires have become sufficient in steering stability.

Therefore, it is conceivable to improve the steering stability by increasing the number of the cord reinforcing layers described above. However, if the number of the reinforcing layers is simply increased, the edge portion of the reinforcing layer is increased. However, since the difference in rigidity with other portions becomes large, stress concentration at those edge portions easily causes separation, and there is a problem that high-speed durability is reduced. Further, if the longitudinal rigidity and the lateral rigidity of the tire become too high with the increase of the reinforcing layer, there is a problem that the steering stability is deteriorated.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic radial tire for a passenger vehicle, which is capable of improving steering stability without impairing high-speed durability by appropriately inserting a reinforcing layer. Especially.

[0005]

A pneumatic radial tire for a passenger car according to the present invention for achieving the above object comprises two carcass layers inside and outside, and both ends of the inner carcass layer are provided around the bead cores on both sides. While folding back so as to wrap the bead filler from the tire inside to the outside, both ends of the outer carcass layer are wound down along the outside of the folded back portion of the inner carcass layer, and the bead filler inner surface and the inner carcass layer. Between and and between the folded-back portion of the inner carcass layer and the outer carcass layer, a reinforcing layer is respectively inserted so as to be located radially inward from the upper end of the folded-back portion, and one of these reinforcing layers The reinforcing layer is made of steel cord, and the other reinforcing layer is made of fiber cord.

Since one reinforcing layer is made of a steel cord and the other reinforcing layer is made of a fiber cord in this manner, the circumferential rigidity can be increased while suppressing the increase in the longitudinal rigidity and the lateral rigidity of the tire. Therefore, the steering stability can be improved by the increase in the circumferential rigidity. In addition, the inner and outer two carcass layers have a so-called 1-1 ply lock structure, and two reinforcing layers are provided between the inner side surface of the bead filler and the inner carcass layer and between the folded-back portion of the inner carcass layer and the outer carcass layer. By separating and inserting in between, the edge parts of the carcass layer and the reinforcing layer are dispersed,
Separation is less likely to occur due to stress concentration at the edge portion, and high-speed durability is not impaired even if the number of reinforcing layers is increased.

The structure of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows a pneumatic radial tire for a passenger vehicle having an aspect ratio of 55% or less, in which 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. An annular bead core 4 and a bead filler 5 are inserted in the bead portion 3, and the pair of left and right bead cores 4,
4, the cord angle with respect to the tire circumferential direction is 70 ° to 90
Both ends of the inner and outer two carcass layers 6 and 7 are mounted. Of these, the inner carcass layer 6 has both ends folded back around the bead core 4 from the tire inner side to the outer side.
The folded portion 6a is arranged so as to wrap the bead filler 5. On the other hand, both ends of the outer carcass layer 7 are wound down from the outside of the folded-back portion 6a of the inner carcass layer 6 to below the bead core 4.

On the carcass layer 7 in the tread portion 1, the cord angle with respect to the tire circumferential direction is 10 ° to 35 °.
Two belt layers 8 that intersect each other are arranged.
Further, on the belt layer 8, three belt cover layers 9 having a cord angle of substantially 0 ° with respect to the tire circumferential direction are arranged so as to cover both end portions or the whole of the belt layer 8.

A reinforcing layer 10 made of a fiber cord is inserted between the inner side surface of the bead filler 5 in the bead portion 3 and the inner carcass layer 6, and the folded portion 6a of the inner carcass layer 6 and the outer carcass layer 7 are joined together. A reinforcing layer 11 made of steel cord is inserted between them. As the fiber cord, it is preferable to use an organic fiber cord such as a nylon cord or an aramid cord, but it is also possible to use an inorganic fiber cord such as a rayon cord or a carbon fiber cord. The inclination angle of the cords forming the reinforcing layers 10 and 11 with respect to the tire circumferential direction is 15 ° to 30 °.
It is good to set to, and it is good to have a relation intersecting with each other.
The upper ends of the reinforcing layers 10 and 11 are located inside the upper end of the folded-back portion 6a of the inner carcass layer 6 in the tire radial direction so that they do not come into direct contact with each other.
Preferably, the upper ends of both of them are displaced from each other in the tire radial direction. Also, both reinforcing layers 10, 1
It is desirable to secure an appropriate amount of the height FH in the tire radial direction from the upper end of the higher one to the end of the belt layer 8 as a flex zone.

According to the pneumatic radial tire for passenger cars constructed as described above, since one of the reinforcing layers 10 and 11 is made of steel cord and the other is made of fiber cord, the longitudinal rigidity and the lateral strength of the tire are increased. Since the circumferential rigidity can be increased while suppressing the increase in rigidity, the steering stability can be improved by the increase in the circumferential rigidity.
That is, if both the reinforcing layers 10 and 11 are made of steel cord, the longitudinal rigidity and the lateral rigidity increase more than necessary, so that the steering stability is decreased, and the reinforcing layers 10 and 1 are
If both of them are composed of fiber cords, the longitudinal rigidity and the lateral rigidity will not be sufficiently increased, so that the reinforcing effect sufficient to satisfy the driving stability of the high-power vehicle cannot be obtained. In the present invention, the reinforcing layer 11 made of steel cord that contributes to the overall rigidity of the tire
And a reinforcing layer 10 mainly composed of a fiber cord that contributes to the circumferential rigidity, the circumferential rigidity is increased so as to sufficiently correspond to the driving performance of the high power vehicle while appropriately suppressing the increase in the vertical rigidity and the lateral rigidity. It is possible to increase it.

Further, as described above, the two reinforcing layers 10 and 1
When installing 1, the carcass layers 6 and 7 of two layers inside and outside 1-
While having a one-ply lock structure, the reinforcing layer 10 is inserted between the inner side surface of the bead filler 5 and the inner carcass layer 6, and the reinforcing layer 11 is provided between the folded-back portion 6a of the inner carcass layer 6 and the outer carcass layer 7. And both reinforcement layers 1
Since the edge portions of the carcass layers 6 and 7 and the reinforcing layers 10 and 11 are dispersed by preventing the terminals 0 and 11 from being adjacent to each other, the separation is performed even if stress is concentrated on these edge portions. Is less likely to occur. Therefore, 2
Even if the reinforcing layers 10 and 11 are provided, the high speed durability is not impaired.

Since the reinforcing layers 10 and 11 may be a combination of steel cords and fiber cords, in the above arrangement structure, the reinforcing layer 10 is made of steel cords and the reinforcing layer 11 is made of fiber cords. You may In the present invention, the height F in the tire radial direction from the upper upper end of the reinforcing layers 10 and 11 to the end of the belt layer 8
The ratio FH / SH to the tire cross-section height SH is 0.
It is preferable to set it in the range of 25 to 0.45. By setting the relationship of FH / SH = 0.25 to 0.45 in this way, it is possible to sufficiently secure the flex zone of the sidewall portion 2, so that the ground contactability of the tire is improved and the ground contactability of the tire is improved. The steering stability can be dramatically improved by the synergistic effect of the improvement and the increase in the circumferential rigidity described above.

The present invention can obtain a remarkable effect particularly when applied to a flat tire having a flatness of 55% or less. In such a tire having an aspect ratio of 55% or less, since the tire cross-sectional height SH is smaller than the tire width, inserting the reinforcing layer has a great influence on high-speed durability and steering stability. With such a configuration, steering stability can be improved without impairing high-speed durability.

[0014]

[Example] Tire size 225 / 50R16, FIG.
In the tire structure shown in (1), a pneumatic radial tire was manufactured in which only the folded back structure of the carcass layer and the arrangement structure of the reinforcing layer were varied as follows. As shown in FIG. 2, both ends of the carcass layer of the inner and outer layers of the conventional tire 1 have a 1-1 ply lock structure as shown in FIG. 2, and a width of 50 mm made of steel cord in the A portion (between the folded-back portion of the inner carcass layer and the outer carcass layer). The reinforcing layer is inserted, and the ratio FH between the height FH from the upper end of the reinforcing layer to the end of the belt layer and the tire cross-section height SH.
/ SH was set to 0.35. As shown in FIG. 3, both ends of the carcass layer of the inner and outer layers of the conventional tire 2 have a 2-0 ply lock structure, and a width made of steel cord in the E portion (between the outer surface of the bead filler and the folded portion of the outer carcass layer). A reinforcing layer of 50 mm was inserted and the ratio FH / SH was set to 0.35.

As shown in FIG. 2, both ends of the inner and outer two layers of the comparative tire 1 have a 1-1 ply lock structure, and a reinforcing layer made of steel cord having a width of 45 mm is inserted in the A portion, and the C portion (bead). A reinforcing layer made of steel cord and having a width of 50 mm was inserted between the inner surface of the filler and the inner carcass layer, and the ratio FH / SH was set to 0.3. As shown in FIG. 2, both ends of the inner and outer two layers of the comparative tire 2 have a 1-1 ply lock structure, and a reinforcing layer having a width of 45 mm made of an aramid cord is inserted in the A portion and an aramid cord is made in the C portion. Inserting a reinforcing layer with a width of 50 mm, ratio FH / S
H was set to 0.3. As shown in FIG. 3, both ends of the inner and outer two layers of the comparative tire 3 have a 2-0 ply lock structure, and a reinforcing layer made of steel cord and having a width of 45 mm is inserted in the D portion (outside of the folded portion of the inner carcass layer). In addition, the width of the F part (between the inner surface of the bead filler and the outer carcass layer) made of aramid cord 50
A mm reinforcing layer was inserted and the ratio FH / SH was set to 0.3.

Both ends of the inner and outer two carcass layers of the comparative tire 4 have a 1-1 ply lock structure as shown in FIG. 2. A reinforcing layer made of steel cord and having a width of 45 mm is inserted in the A portion, and the B portion (bead). A reinforcing layer made of aramid cord and having a width of 50 mm was inserted between the outer surface of the filler and the folded portion of the inner carcass layer, and the ratio FH / SH was set to 0.3. As shown in FIG. 2, both ends of the inner and outer two layers of the comparative tire 5 have a 1-1 ply lock structure, a reinforcing layer made of steel cord having a width of 45 mm is inserted in the B portion, and an aramid cord is formed in the C portion. Inserting a reinforcing layer with a width of 50 mm, ratio FH / S
H was set to 0.3. As shown in FIG. 2, both ends of the inner and outer two layers of the comparative tire 6 have a 1-1 ply lock structure, and a reinforcing cord made of steel cord having a width of 45 mm is inserted in the A portion, and a steel cord is made in the B portion. Inserting a reinforcing layer with a width of 50 mm, ratio FH / S
H was set to 0.3.

As shown in FIG. 2, both end portions of the inner and outer two carcass layers of the tire 1 of the present invention have a 1-1 ply lock structure, a reinforcing layer made of steel cord having a width of 35 mm is inserted in the A portion, and the C portion is inserted in the C portion. Insert a reinforcing layer made of aramid cord with a width of 20 mm to obtain a ratio FH / S
H was 0.4. As shown in FIG. 2, both ends of the inner and outer two carcass layers of the tire 2 of the present invention have a 1-1 ply lock structure, a reinforcing layer made of steel cord having a width of 45 mm is inserted in the A portion, and an aramid cord is formed in the C portion. Insert a reinforcing layer with a width of 50 mm to obtain a ratio FH / S
H was set to 0.3. As shown in FIG. 2, both ends of the inner and outer two carcass layers of the tire 3 of the present invention have a 1-1 ply lock structure, a reinforcing layer made of aramid cord having a width of 50 mm is inserted in the A portion, and a steel cord is formed in the C portion. A reinforcing layer with a width of 45 mm is inserted, and the ratio FH / S is
H was set to 0.3.

The steering stability and high speed durability of these tires were evaluated by the following test methods, and the results are shown in Table 1. Steering stability: Test tires were mounted on a passenger car with an air pressure of 2.5 kg / cm ^{2 and} a displacement of 3000 cc, run on a slalom test road on which pylons were set at regular intervals, and the average speed was evaluated. The evaluation results are shown by an index with the conventional tire 1 as a reference (100). The larger this index value, the better the steering stability.

High-speed durability: A test tire was subjected to a single drum test at a high speed and evaluated by the distance until separation occurred at a bead portion or a side portion. The evaluation results are shown by an index with the conventional tire 1 as a reference (100). The higher the index value, the better the high speed durability.

[0020] As can be seen from Table 1, the tires 1 to 3 of the invention were able to improve the steering stability as compared with the conventional tire 1 with almost no loss of high-speed durability. On the other hand, in Comparative tires 1 to 6, when the steering stability was improved as compared with the conventional tire 1, the high speed durability was significantly reduced.

[0021]

As described above, according to the present invention, two inner and outer carcass layers are provided, and both ends of the inner carcass layer are wrapped around the left and right bead cores with the bead filler from the tire inside to the outside. With folding back,
Both ends of the outer carcass layer are wound down along the outside of the folded-back portion of the inner carcass layer, between the inner surface of the bead filler and the inner carcass layer, and the folded-back portion of the inner carcass layer and the outer side. The reinforcing layer is inserted between the carcass layer and the carcass layer so as to be located radially inward of the upper end of the folded portion, and among these reinforcing layers,
Since one reinforcing layer is made of steel cord and the other reinforcing layer is made of fiber cord, the circumferential rigidity is increased while suppressing the increase in the longitudinal rigidity and the lateral rigidity of the tire, thus improving the steering stability. Since the carcass layer and the edge portions of the reinforcing layer are dispersed, high-speed durability is not impaired even if the number of reinforcing layers is increased.

[Brief description of drawings]

FIG. 1 is a half cross-sectional view showing a pneumatic radial tire for passenger cars according to an embodiment of the present invention.

FIG. 2 is 1-in a bead portion of a carcass layer having a two-layer structure.
It is sectional drawing which shows the position of 1 ply lock structure and a reinforcement layer.

FIG. 3 is a view of a bead portion of a carcass layer having a two-layer structure.
It is sectional drawing which shows the position of a 0 ply lock structure and a reinforcement layer.

[Explanation of symbols]

 3 bead part 4 bead core 5 bead filler 6 inner carcass layer 6a folded part of inner carcass layer 7 outer carcass layer 10, 11 reinforcing layer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location // B60C 9/18 F 8408-3D 9/22 D 8408-3D

Claims (1)

[Claims] 1. A carcass layer is provided inside and outside, and both ends of the inside carcass layer are folded back around the left and right bead cores so as to wrap a bead filler from the inside of the tire to the outside, and both ends of the outside carcass layer are The inner carcass layer is wound down along the outside of the folded portion, and is reinforced between the inner surface of the bead filler and the inner carcass layer and between the folded portion of the inner carcass layer and the outer carcass layer. Air for passenger cars in which the layers are inserted so as to be located radially inward of the upper end of the folded portion, and one of these reinforcing layers is made of steel cord and the other reinforcing layer is made of fiber cord. Radial tires with.