JPH0218104A - Pneumatic tyre for high speed excellent in cornering performance - Google Patents

Abstract

PURPOSE:To reinforce the rigidity of a side part favorably and improve the cornering performance of a pneumatic tyre for high speed by arranging a side part reinforcing means which can form a fixed area for a bead core and a belt in a side wall part. CONSTITUTION:In a tyre, a bead core 5 is buried inside of a bead part 1. A carcass 6 composed of the cord reinforced layer with at least one ply is extended from the bead part 1 toward a side wall part 2 and a tread part 3. Further, a belt 7 composed of plural cord reinforced layers is buried inside of the tread part 3. In this case, a side part reinforcing means 9 forming a fixed area for the bead core 5 and belt 7 is arranged in the side wall part 2. In the side part reinforcing means9, a more number of layer arrangement including the cord reinforced layer of the carcass 6 in the area from the bead core 5 to the part overlapping the belt 7 are distributed outside the bead core 5.

Description

[Detailed Description of the Invention] (Industrial Field of Application) For high-speed pneumatic tires mainly used for high-speed driving, such as racing cars, rally cars, and high-performance sports cars, it is advantageous to improve cornering performance. This is what we are trying to achieve.

(Prior art) In order to improve the cornering performance of high-speed pneumatic tires, it is necessary to install wider tires or, for the same tire, to increase the so-called foot width of the tire by combining it with a wider rim. Although this method is known, it cannot be used when tire size and rim size are restricted.

Another effective way to improve the cornering performance of a tire without changing the tire size or rim size is to increase the side stiffness.
According to Japanese Patent No. 63806, it is disclosed that a side edge of a plurality of carcass plies rolled up around a bead core is folded back to a height that reaches a belt end region serving as a tread reinforcing member for one carcass ply.

(Problem to be Solved by the Invention) When trying to improve the cornering performance of high-speed pneumatic tires using the same tire size and rim size, a simple high turn-up method such as that used in the conventional doffing technology actually results in side It was found that there is a limit to the increase in stiffness of the parts. The present invention therefore seeks to achieve an advantageous increase in side stiffness to help achieve the sufficient improvement in cornering performance required in high-speed pneumatic tires.

(Means for Solving the Problems) This invention consists of a pair of bead portions and sidewall portions, and a tread portion spanning between the sidewall portions, and includes a bead core embedded in each bead portion, and a tread portion extending from one of the bead portions to the other. A pneumatic tire comprising: a carcass made of at least one cord reinforcing layer extending in a toroidal manner through a sidewall portion and a tread portion; and a belt made of a plurality of cord reinforcing layers embedded in the tread portion; The cord on the outside of the carcass, which extends along the bead core until it overlaps with the belt, has a larger number of layers on the outside of the bead core than on the inside of the bead core, including the cord reinforcing layer of the carcass. A high-speed vehicle with excellent cornering performance, characterized in that the side wall portion is provided with a side portion reinforcing means consisting of a reinforcing layer, and the side portion reinforcing means forms a fixing region for each of the bead core and the belt. It is a pneumatic tire.

Here, the term "side reinforcement means" may include at least a part of the cord reinforcement layer that constitutes the carcass, which is the general body reinforcement of pneumatic tires, but in general, it is possible to include the cord reinforcement layer that constitutes the carcass, which is the general body reinforcement of pneumatic tires. The cord reinforcement layer is located on the outside of the bead core and has a more distributed layer arrangement than the inside of the bead core. It means something that forms overlapping fixed areas.

This cord reinforcing layer is preferably made of organic fibers, particularly high-strength fiber materials, which serve as the rubber coating for the cord, as well as those constituting the carcass ply. 60～
The cord angle arrangement is 90°. The cord material can also sometimes be a metal wire cord.

As for the cord reinforcing layer of the belt, not only organic fibers but also inorganic fibers and metal wires can be used as usual.

Now, FIG. 1 shows the basic structure of a high-speed pneumatic tire according to the present invention in a cross section taken from the right hand side of the tire.
2 is a bead portion, 2 is a sidewall portion, 3 is a tread portion, and 4 is a rim on which a tire is mounted at bead portion 1. Further, 5 is a bead core, 6 is a carcass, 7 is a belt, and 8 is a bead stiffener.

In this example, the carcass 6 includes a turn-up ply 6a that is wound around the bead core 5 from the inside of the tire to the outside, and a down ply 6b that is wound around the bead core 5 from the outside of the tire to the inside. The winding end of the turn-up ply 6a is overlapped with the side edge of the belt 7, and is generally called an up-down method. It is unique in that it did so.

In other words, the number of layers of the cord reinforcing layer of the carcass 6 extending along the bead core and from there until it overlaps with the belt is distributed more on the outside than on the inside of the bead core 5, and the ply is distributed here. Rewind 6
a' and the unwinding of the down ply 6b are used as the side reinforcing means 9.

By the way, JP-A No. 61-263, which was developed based on the conventional technology.
As is clear from the comparison in FIG. 2 of a typical example of the carcass layer arrangement for reducing sensitivity to load movement during turning and braking, disclosed in Japanese Patent No. 806, the bead core 5
There is more distribution on the inside than on the outside, and in order to advantageously increase the side rigidity of the tire, use a wide tire or combine it with a wide rim that increases the foot width of the tire. It is clear that the present invention is essentially different from the above-mentioned basic structure in that the empirical fact that it is rather compatible is ignored here.

Next, in FIG. 3, in the basic configuration shown in FIG. 1, the unwinding 6a' of the turn-up ply 6a is held between the lower half and between the stiffener 8 and the unwinding of the down ply 6b. An example is shown in which side inserts 10 made of a cord reinforcing layer are arranged to help increase torsional rigidity between the bead parts.

Here, the side insert 10 has a layer of rubber coating of a cord made of an organic fiber, especially a high-strength fiber material, or a metal wire cord, at a distance of 20 mm with respect to the meridian cross section of the tire.
Preferably, it is applied with a cord angle arrangement of between 45° and 45°.

From FIG. 4 onwards, different examples of application of the side reinforcing means 9 are diagrammatically shown.

In FIG. 4, the down ply 6b is moved inside the turn 68', and in FIG. 5, the down ply 6b and turn 6a' are arranged.
In FIG. 6, the down ply 6b is omitted and the additional cord reinforcing layer 11 and the winding 68' are used as the side reinforcing means 9. On the contrary, in FIG. 7, a ply 6 without winding is used instead of a turn-up ply 6a.
Another arrangement, FIG.
In particular, two down plies 6b sandwich a ply 6c, which also does not have curling, between it and the bead core 5, and the two down plies 6b serve as side portion reinforcing means.

FIG. 9 also shows that a single particularly wide ply 6 is used to form a turn 6' and a further folded unwind 6", and the side part is strengthened by the turn 6' and the unwind 6". FIG. 10 shows an arrangement in which an additional cord reinforcing layer 11 is added to this arrangement.

In the above, the additional cord reinforcing layer 11 can also be a cord made of organic fibers or particularly high-strength fiber materials, or sometimes a rubber coating of a metal wire cord.
It is desirable that the cord be applied at a cord arrangement angle that is aligned with the ply cord of the force sludge 6.

(Function) The cornering performance of pneumatic tires can be improved by increasing the side rigidity, and although it is effective to use wider tires or widen the tire foot width with wider rims to achieve this, When there are restrictions on tire size and rim size, it is necessary to increase the side stiffness of the same tire, similar to increasing the width of the foot, but it is advantageous depending on the reinforcement arrangement of the side section of the tire. The inventors discovered through their research that the reinforcement arrangement on the side part consists of a layer arrangement distribution of more cord reinforcement layers on the outside of the bead core than on the inside, as described above. The cord reinforcing layer can occupy at least a part of the carcass ply, but of course the use of an additional cord reinforcing layer does not affect the essential reinforcing action of the pneumatic tire by the carcass. However, the side part reinforcement means constituted by the outer cord reinforcing layer, in which the number of layers including the cord reinforcing layer of the carcass is distributed more on the outside than on the inside of the bead core, By forming a fixing area for the bead core and the belt, it particularly advantageously contributes to increasing the rigidity of the side part, and as a result, high-speed The cornering performance of the tire is improved.

When the tire is inflated, the cord reinforcement layer that occupies the outside of the tire in the bead core 5 is where tension is applied in the meridian section of the tire, and if it is free at the upper end like the general folded end of the carcass. If so, the above tension will be significantly reduced.

On the other hand, if the upper end of the cord reinforcing layer is sandwiched between the belt under strong tension and the carcass immediately below it to form a fixed area, the lower end of the cord reinforcing layer will originally have a bead core and Since a fixed area is formed between the rim flange and the cord reinforcement layer, the above-mentioned cord reinforcement layer is subjected to a large tension due to the air pressure inside the tire. This allows the material to have greater compression stiffness and bending stiffness, resulting in higher side stiffness.

On the other hand, the curvature of the cord reinforcement layer located on the outside of the bead core is smaller than that on the inside (in this case, the curvature is larger), and the stiffness is greater than when a load is applied to the inside carcass cord. Therefore, the rigidity of the side part can be increased.

The former effect described above with respect to increasing sidewall stiffness can be compared primarily to the behavior that occurs in a flatter tire, and the latter to the behavior of tension in a tire mounted on a wider rim. Both of these effects are simultaneously exerted in the present invention, and thus, at the bead portion, which is actually the upper and lower fixed point of the bead portion reinforcing means, the number of layers of the cord reinforcing layer on the outside of the bead core, which has a smaller curvature, is reduced to the number on the inside. Coupled with the effect of the upper fixing point, which has more cord reinforcing layers than the number of cord reinforcing layers and forms a fixing area that overlaps the belt of the tread, it is possible to increase the sidewall rigidity more efficiently.

(Example) A test tire of tire size 240/655R17 having the following specifications was prepared according to the diagram in Fig. 3, and a second
Cornering performance was tested together with a comparison tire of the same size as shown in the figure.

Carcass cord material: nylon, cord size: 1260d/2
.

Number of strokes 62.8 15cm, cord angle 6° Number of plies 2 Side insert cord material Steel Number of strokes 38 / 5 cm Number of cords used 2 Cord size 1 x 5 Cord angle 22゜ Belt cord material Steel Number of strokes 38 15cI11 Number of cords used 2 Code size 1 x 5 Code angle 24
The tests were conducted individually by a plurality of experienced test drivers over a distance of 0km, and the results of the lap time and feeling were summarized and expressed as an index with the results of the comparison tire set as 100, and are shown in the following table.

Table 1 FIGS. 4 to 10 are tire cross-sectional diagrams illustrating modified embodiments.

1... Bead part 2... Sidewall part 3... Tread part 4... Rim 5... Bead core 6... Carcass 7... Belt
9...Side portion reinforcing means 11...The larger the value of the additional cord reinforcing layer index, the better (effect of the invention) According to this invention, the cornering performance of a high-speed pneumatic tire can be advantageously improved. can.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a tire showing the basic structure of this invention. Figure 2 is a cross-sectional view of a comparison tire.

Claims (1)

[Claims] 1. Consisting of a pair of bead portions and sidewall portions, and a tread portion spanning between the sidewall portions, a bead core embedded within each bead portion, and a sidewall extending from one of the bead portions to the other. A pneumatic tire comprising: a carcass comprising at least one cord reinforcing layer extending in a toroidal manner through the tread portion; and a belt comprising a plurality of cord reinforcing layers embedded within the tread portion; , the number of layers including the cord reinforcement layer of the carcass extending from there until it overlaps with the belt is distributed more on the outside than on the inside of the bead core, from the cord reinforcement layer on the outside. A high-speed pneumatic tire with excellent cornering performance, characterized in that the sidewall section is provided with a side reinforcement means, the side reinforcement means forming a fixation area for each of a bead core and a belt. . 2. The pneumatic tire according to claim 1, wherein the side portion reinforcing means consists of a ply winding part of the carcass and a ply unwinding part along with the ply winding part of the carcass in an up-down lamination method. 3. The pneumatic tire according to claim 1, wherein the side portion reinforcing means comprises a ply-wound portion of the carcass that is of a high turn-up type and an additional cord reinforcing layer along the ply-wound portion of the carcass. 4. The air according to claim 1, wherein the side portion reinforcing means comprises an up-down layered carcass ply winding part and/or a ply unwinding part along this, and an additional cord reinforcing layer. Included tires. 5. The pneumatic tire according to claim 1, wherein the side portion reinforcing means comprises an unwinding portion of one of the two halves of the at least two-ply carcass, and an additional cord reinforcing layer along the unwinding portion. 6. The pneumatic tire according to claim 1, wherein the side portion reinforcing means is at least two plies of one of the two halves of the at least three ply carcass. 7. The pneumatic tire as set forth in claim 1, wherein the side portion reinforcing means comprises a ply winding portion and a folding and unwinding portion of the carcass in which the side portion reinforcing means is of a high turn-up end folding and winding type. 8. The pneumatic tire according to claim 1, wherein the side portion reinforcing means comprises a ply winding portion, a folding and unwinding portion of the carcass, and an additional cord reinforcing layer in which the side portion reinforcing means is of a high turn-up end folding and winding type.