JPS61253205A - Non-symmetrical pneumatic tire for racing - Google Patents

Abstract

PURPOSE:To enhance operational stability of pneumatic tire for racing by laying together both ends of a flipper made of aromatic polyamide cord with the specific cored angle outside the top of the bead filler rubber in the radial direction and specifically arranging a wire insert layer in the bead and the side wall part which turn outwards at the time of the vehicle equipping posture. CONSTITUTION:A flipper 5 is constituted with an aromatic polyamide cord having the cord angle of 40-70 deg. to the cross section of a tire meridian, and a bead filler rubber 6 is wrapped with the flipper 5, with its both ends laid together at a lower step in a position somewhat exceeding the top of the bead filler rubber 6 in the radial direction of the tire. Furthermore, in the inside opposing the side adjoining the carcass returning part 4, a wire insert 2 with a cord angle of 40-70 deg. to the cross section of the meridian is placed only on the side facing outwards at the vehicle equipping time. The wire insert is positioned within the range of 40-80% of the tire height H. Based on this arrangement, operational stability can be improved.

Description

[Detailed Description of the Invention] (Industrial Application Field) The technical content described in this specification regarding improving the steering stability of pneumatic racing tires is to improve the bending rigidity of the tire sidewall,
This is related to the results of development research that investigated the usefulness of creating appropriate asymmetry.

Generally, this type of tire is suitable for rapid turning at high speeds.

The above research originated from the fact that tires are used under severe conditions such as acceleration and braking, and that the rigidity and balance from the bead area to the sidewall area determines the time lap.

(Conventional technology) The demand for improving the handling stability of racing tires is inevitable, and on the other hand, there are restrictions on tire width (prohibition of over fenders) and maintenance of conditions similar to those of ordinary cars (vehicle In order to suppress vehicle weight reduction due to modification), etc.
Although negative factors such as the decrease in tire air volume are being forced to increase, various countermeasures are being considered. It is not possible to seek teachings from known literature.

(Problems to be Solved by the Invention) In recent years, with the tightening of regulations regarding tires for racing automobiles as mentioned above, it has become necessary to improve handling stability, which must meet the harsh operating conditions required of racing tires. It is extremely difficult to secure this.

For example, if the bead area and sidewall area are reinforced with reinforcing material to compensate for the lack of bending rigidity in the tire sidewall, another problem arises: the tire becomes difficult to bend during load transfer. This results in a reduction in the ground contact area, and particularly an increased tendency for buckling in the tread portion, which impairs both braking and acceleration performance, and also causes uneven wear on the tread, which comes at the cost of improved handling stability.

It is possible to effectively improve the handling stability of racing pneumatic tires while advantageously avoiding such drawbacks.
This is the object of this invention.

(Means for Solving the Problems) This invention uses a carcass consisting of a single or multiple plies of rubberized cord, including a folded part in which at least one ply is wound from the inside to the outside of a bead core, as body reinforcement, and As a reinforcing means from the bead part to the sidewall area of the body reinforcement, at least one layer of flipper made of organic fiber cord wound inside and outside the bead core, and wrapped with the flipper on the bead core and having a Shore A hardness of 75 to 98.
This is a pneumatic tire equipped with a relatively hard bead filler rubber, and the flipper uses an aromatic polyamide cord with a cord angle inclined at 40 to 70 degrees with respect to the meridian cross section of the tire. The outer end is stepped, and the bead filler rubber has a thickness that gradually decreases in that direction, and is arranged so as to face each other across the substantially triangular top end. and the bead filler rubber on the opposite inner side, there is a metal cord array extending over a range of 40 to 80% of the tire height on the bead core at an angle of 40 to 70'' with respect to the meridian cross section of the tire, and the above-mentioned By arranging the wire insert layer covered by the folded part of the carcass in the bead and sidewall area only on the side facing outward when the tire is mounted on the vehicle, the bending stiffness of the sidewall is differentiated. It is an asymmetric pneumatic tire.

The inventors have been conducting experiments and studies on methods of strengthening the bead area or sidewall area without sacrificing other performance of the tire, but the above strengthening generally improves handling stability, especially in turning. In order to improve performance, disadvantages in terms of acceleration performance, braking performance, and even uneven wear cannot be avoided. As we continued to search for more effective solutions, we focused on the load transfer during cornering and found that most of the load is borne by the sidewall area facing outward when the tire is mounted on the vehicle. It turned out that it was.

Based on this knowledge, further experiments were carried out, and it was found that in the above-mentioned position, the reinforcing means that causes a difference in bending stiffness to be lower in the sidewall area facing the center of the vehicle than in the sidewall area facing outwards was added. By applying it to the load-bearing bead area and sidewall area, acceleration performance,
It has been found that it is possible to effectively enhance steering stability during turns without deteriorating braking performance or uneven wear.

A wire insert layer is particularly suitable for implementing this reinforcing means.

That is, FIG. 1 shows a meridian cross section of an asymmetric pneumatic racing tire according to the present invention, and 1 in the figure indicates the carcass,
2 is a wire insert layer, 3 is a bead core, 4 is a fold of the carcass 1, 5 is a flipper, and 6 is a bead filler rubber.

Carcass 1 is rubberized cord ply 1-1 to 1-4
Although the diagram shows a case of a bias structure in which four layers are stacked with the cord directions intersecting each other between adjacent layers, it is also possible to apply a radial structure in which a single ply or at most two plies are stacked. Often, the cord material may also be organic fibers such as nylon, polyester or other aromatic polyamides, and sometimes metal, particularly steel filaments.

The carcass 1 has a folded part 4 in which at least one of the plies 1-1 to 1-4, two plies 1-1 and 1-2 in the illustrated example, are wound around the bead core 3 from the inside to the outside. This carcass 1 is used as body reinforcement for a pneumatic tire.

This body reinforcement is achieved by flippers 5 and bead filler rubber 6 from the bead area to the sidewall area.
In particular, the bead-sidewall area only on the side facing outward in the vehicle mounting position of the tire is reinforced by the wire insert layer 2.

The flipper 5 winds up the bead filler rubber 6 on the bead core 3 by winding it in and out of the bead core 3 with at least one layer of cords made of aromatic polyamide arranged in a direction inclined at 40 to 706 with respect to the meridian cross section of the tire. Wrap around. The flipper 5 provides a step at the radially outer end of the tire.

The bead filler rubber 6 has a maximum rubber thickness on the side in contact with the bead core 3, and the thickness gradually decreases in the radial direction of the tire to form a substantially triangular cross-sectional shape. The winding ends should be placed facing each other. This bead filler rubber has a Shore A hardness of 75.
~98 relatively hard formulation.

The wire insert 2 is arranged between the bead filler rubber 6 on the inner side of the flipper 5 opposite to the side adjacent to the carcass folded part 4. The wire insert layer is an array of metal, particularly steel, cords extending over a range of 40 to 80% of the tire height on the bead core 3 at an angle of 40 to 70 degrees with respect to the meridian cross section of the tire. By arranging in the bead sidewall area only on the side facing outward in attitude, an appropriate range of bending stiffness in the sidewall of the tire is introduced according to the invention.

(Function) According to the present invention, the asymmetrical reinforcement of the tire sidewall only on the side facing outward when the tire is mounted on a vehicle is sufficient to ensure steering stability during high-speed cornering, while The difference in bending stiffness in the sidewall on the non-reinforced side can help maintain other properties such as acceleration performance, braking performance, and even uneven wear.

Here, the flipper 5 winds up the inside and outside of the bead core 3 and wraps the bead filler rubber with this flipper.
In particular, consideration was given to making the bead area the strongest at the bottom and reducing bending rigidity towards the sidewall area.
The reason why the aromatic polyamide cords in this flipper are arranged at an angle of 40 to 70'' with respect to the meridian cross section of the tire is because if the cord angle is less than 40 degrees, there will be a delay in torque transmission during sudden acceleration or braking. The steering stability decreases,
Furthermore, if the angle exceeds 70°, even though aromatic polyamide cords are used, the required bending rigidity in the tire radial direction cannot be obtained, and it is not possible to improve the steering stability. The reason for facing each other with a step at the winding end is to avoid a rigid fault, to more effectively improve steering stability, and to prevent separation at the cord end.

Next, if the bead filler rubber has a Shore A hardness of less than 75, it will not be able to provide the necessary reinforcement in the bead area, while if it exceeds 98, it will cause problems in workability.
It is also necessary to have a hardness in the range of 5 to 98, and to form a substantially triangular cross-sectional shape in which the thickness gradually decreases in the radial direction of the tire from the maximum rubber thickness on the bead core. The arrangement in which the bead filler rubber 6 is wrapped and rolled together with the bead core 3 and the winding end of the flipper is stepped is to eliminate the rigid stepped layer in the sidewall area.
This is to adjust the rigidity balance from the bead area to the sidewall area.

The wire insert layer 2 is arranged between the bead filler rubber on the inside of the flipper 6 on the side that contacts the carcass folded part 4, thereby increasing the cord durability by bringing the wire insert layer as close as possible to the bending center axis of the side wall. In order to maintain the tire height, if it is less than 40% of the tire height,
The effect of reinforcement in the sidewall area is not reached, and if it exceeds 80%, the movement of the sidewall during load transfer of the tire will be excessively suppressed, and there will also be problems with durability, so it should be kept within this range. is necessary. Regarding the cord angle, it is necessary to set the cord angle between 40 and 70 degrees, as an inclination of less than 40' will cause a delay in torque transmission, and an inclination of more than 70 degrees will make it difficult to achieve the required bending stiffness in the tire radial direction. be.

It should be noted that this wire insert layer 2 must be covered on its radially outer side by a turn-up part 4 of the carcass, since this is necessary in order to prevent separation at the ends of the cord consisting of wire filaments.

(Example) Tire size 1551555-1 on the rear wheel of a racing vehicle
A test tire of 44 ply was assembled on a rim of 7.0 JJ-14, and the internal pressure was 2.5 kgf/cm2.For the front wheel, a test tire of tire size 1751555-144 ply was assembled on a rim of 7.0 JJ-14, and the internal pressure was 1. .8kgf/
It was installed under the condition of "cm".

These test tires had nylon 1260d cords arranged in a layered manner with the cords alternating in direction as shown in Figure 1 at a cord angle of 656 with respect to the meridian cross section of the tire. counting, both the 1st ply 1-1 and the 2nd ply 14 wind up the bead core 3 from the inside to the outside, and the ply 1-5.4st ply 1.
．． Although the example has been shown as an up-down structure in which the bead core 3 is wound up with 4 plies, it goes without saying that the number of plies can be further increased, such as a 4-ply up structure and a 2-ply down structure.

Next, as the flipper 5, aromatic polyamide cords of 1500 d/3 are arranged at an inclination angle of 45 degrees with respect to the meridian cross section of the tire, and are wound inside and outside the bead core 3 to wrap the bead filler rubber 6 inside and outside. However, the rolled ends were faced to each other with a step that was much higher on the inside than on the outside.

The bead filler rubber 6 has a Shore A hardness of 95, and the height in the radial direction shown in the figure is 40 ± 5 mm 5 Same <h
1' was spread over 30±5 mm.

Wire insert layer 2 is I X 5 Xo, 69mm
The steel cords are arranged at an angle of 456 with respect to the tire meridian cross section, and in this example, the angles of the two cords intersect with each other. It was placed so that it would fit within the step at the top.

Here, the 1st ply 1-1 of the carcass 1 has a height of 77.5±7.51 in the radial direction shown by ho in the figure, and covers all the reinforcing material ends, and is connected to the flipper 5. Step SO+ Then step SL between the wire insert layer 2, step S2 between the wire insert layers, step S3 again between the flipper 6 and the 2nd ply 1 of the carcass 1. ．． Step S4 between 2 and 2 was 10 mm, but the tire height H (97 mm for size 1751555-144ply) was 7 to 2.
A range of 0% is suitable in terms of rigidity balance.

Regarding the left side of FIG. 1, that is, the side wall on which the wire insert layer is not arranged, which faces the vehicle in the tire mounting position, the step S01 between the folded end of the 1st ply L of the carcass 1 and the flipper 5 is 10 mm.

The step S5 between the flippers 5 was 25 mm, and the step S6 between the flippers 5 and the second ply 1-2 was 15 mm.

The tire A according to the present invention described above, the comparative tire B on the right side of FIG. 1 in which the reinforcing means described above is applied to both side walls, and the conventional tire C on the left side in FIG. 1 in which a similar structure is applied to both side walls. We made prototypes of each and conducted comparative tests on handling stability, and obtained the results shown in the table below.

*1 Time Lap is an index based on the measurement results under the following conditions, with the performance of conventional tires set as 100, and the smaller the value, the better.

Test Conditions (Effects of the Invention) According to the present invention, despite the restrictions that have recently become stronger in pneumatic racing tires, it is possible to improve steering stability during cornering at high speeds without deteriorating the performance of other tires. It can be realized without

[Brief explanation of drawings]

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

Claims (1)

[Scope of Claims] 1. A carcass consisting of a single or multiple ply of rubberized cord, including a folded part in which at least one ply is wound from the inside to the outside of the bead core, is used as body reinforcement, and from the bead area of this body reinforcement At least one layer of flipper made of an organic fiber cord wound inside and outside the bead core as a reinforcement means over the sidewall area, and a relatively hard bead filler having a Shore A hardness of 75 to 98 wrapped in the flipper on the bead core. It is a pneumatic tire equipped with rubber, and the flipper uses an aromatic polyamide cord with a cord angle inclined at 40 to 70 degrees with respect to the meridian cross section of the tire, and has a step at the outer end in the radial direction of the tire. In addition, the bead filler rubber, whose thickness gradually decreases in this direction, is arranged so as to face each other across the substantially triangular apex thereof. Between the filler rubber and the tire, there is an array of metal cords extending over a range of 40 to 80% of the tire height on the bead core at an angle of 40 to 70 degrees with respect to the meridian cross section of the tire, and at the folded part of the carcass. An asymmetric pneumatic tire for racing, in which the bending stiffness of the sidewall is differentiated by arranging a covered wire insert layer in the bead and sidewall area only on the side facing outward when the tire is mounted on a vehicle.