JPH0466310A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To secure steering stability by providing above a rim flange an adjoining portion where the body portion of a carcass and its rolling-up portion adjoined each other through reinforcing layers and eliminating a bead apex in the adjoining portion, thus reducing a tire weight and also maintaining the rigidity of a bead portion. CONSTITUTION:A carcass 6, is furnished with a rolling-up portion 6b which can be rolled up around the bead core 5 from the inside to outside of a tire, along its body portion 6A extending from a tread portion 2 to the bead core 5 of a bead portion 4 through a side wall portion 3. Carcass rolling-up height Hc which is a radial distance from a bead base line BL is set to a half of tire section height Ht or more. Furthermore, two reinforcing layers 9A and 9B are arranged between the body portion 6A and the rolling-up portion 6B, in the range between an upper point X2 which stays at 0.25 time the tire section height Ht and a lower point X1 which is the upper edge of a rim flange 11. In addition, an adjoining portion Y where the body 6A and the rolling-up portion 6B adjoin with each other through the reinforcing layers 9A and 9B, is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pneumatic tire, and particularly to a pneumatic radial tire that can realize a light bead portion without impairing handling stability.

[Conventional technology]

Conventionally, as shown in Fig. 3, in pneumatic tires, the gap between the main body part A of the carcass and the raised part B of the carcass is filled with a bead apex C made of rubber at the tire part. There is. This bead apex C fills the void and maintains the shape of the bead, and also hard rubber (for example, J
By using rubber with an ISA hardness of 60 to 90, the bending rigidity of the bead portion is increased and the steering stability of the tire is improved.

[Problem to be solved by the invention]

However, in recent years, as vehicles have improved in performance and fuel efficiency, it has become necessary to reduce the weight of tires. In order to reduce tire weight, for example, increasing the volume of the trend will result in a decrease in grip performance and wear life, and reducing the volume of the sidewall portion will lead to damage to the carcass layer due to external trauma, making it difficult to achieve. It is.

On the other hand, reducing the volume of the bead part may reduce the bead apex, which occupies the largest volume in the bead part. This was a matter that was not carried out.

An object of the present invention is to provide a pneumatic tire that is useful for reducing the weight of the tire without reducing the rigidity of the bead portion or the steering stability.

[Means to solve the problem]

The present invention has a carcass that is integrally provided with a winding part for winding up bead cores from the inside to the outside in the axial direction of the tire, in a toroidal main body part extending from the tread part through the sidewall part to a pair of dowel cores, and The height in the radial direction from the bead baseline at the upper end of the rim is at least 1/2 of the tire cross-sectional height, and the distance from the lower point, which is the upper end of the rim flange, from the bead baseline is 1/2 of the tire cross-sectional height.
A reinforcing layer made of a plurality of high-tensile cords is arranged between the main body part and the winding part including the region between the upper point 74 and the lower part. A pneumatic tire comprising an adjacent portion in which the main body portion and the rolled-up portion are adjacent to each other with a reinforcing layer interposed therebetween, radially outward from the point.

[Effect]

The adjacent part where the main body part and the winding part of the carcass are adjacent to each other via the reinforcing layer exists above the rim flange, and there is no bead apex in the adjacent part, so the volume of the bead apex is smaller compared to conventional tires. Therefore, tire weight can be reduced and fuel efficiency improved.

In addition, the reinforcing layer compensates for the decrease in bead rigidity due to the reduction or omission of the bead apex, and suppresses the elongation deformation caused by the tensile force that occurs in the carcass at the bead when a lateral force is applied to the tire. As a result, the rigidity of the bead part can be maintained and steering stability can be maintained.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows one side of a radial cross section of an embodiment of the first invention in a standard state assembled on a regular rim 10 and filled with a regular internal pressure.

The tire 1 includes a carcass 6, a belt layer 7, and a plurality of layers.
In this example, two reinforcing layers 9A and 9B and a small bead apex 8 are arranged.

The carcass 6 has a main body part 6A extending from the tread part 2 through the sidewall part 3 to the bead core 5 of the bead part 4, and is provided with a winding part 6B that is rolled up around the bead core 5 from the inside to the outside of the tire. The carcass layer 6 is composed of one or more plies in which radially arranged cords are arranged in parallel, and the cords are made of organic fibers such as nylon, polyester, rayon, aromatic polyamide, etc.
Alternatively, metal, carbon fiber, etc. can be used. Naori - Kas 6
may also include plies that are not wound around the bead core 5 and plies that are wound from the outside in the axial direction of the tire. Further, in order to reduce the weight of the tire, it is desirable that the carcass 6 also be constructed using lightweight cords and a small number of plies.

The belt layer 7 is arranged on the inner side of the trend part 2 and on the carcass 6.
In this example, the belt ply consists of two inner and outer belt plies with cords crossing each other. It is also preferable to use a lightweight and high-tensile cord, such as an aromatic polyamide cord, for the cord of the belt layer. In this case, it is also good to arrange an organic fiber cord covering the outer surface of the belt layer 7, for example, a spirally wound band. .

The bead apex 8 has a JISA hardness of 60 to
90, the bead core 5 has a tapered triangular cross-sectional shape extending outward in the tire radial direction between the main body portion 6A and the winding portion 6B, and the bead apex 8 is made of a bead base at the upper end in the tire radial direction. The height l (a) of the upper end of the bead apex, which is the distance from the line BL, is the lower point X1, which is the upper end position of the flange 11 of the rim 10.
The height is set to be less than or equal to the height Hf. This reduces the volume of the bead apex 8 to a greater extent than in conventional tires, which is more than twice the height Hf, contributing to the weight reduction of the tire.

The carcass entry height HC, which is the distance in the radial direction from the bead baseline BL of the winding portion 6B, is set to be equal to or more than 1 layer 2 of the tire cross-sectional height Ht. This maintains the rigidity of the lower portion of the sidewall portion 3 from the door portion 4.

Note that the tire cross-sectional height Ht refers to the radial distance from the bead baseline BL to the highest point of the trend surface.

The two reinforcing layers 9A and 9B are arranged between the main body part 6A and the rolled-up part 6B of the carcass 6.

These reinforcing layers 9, 9B suppress elongation due to the tensile force generated in the bead portion 4 when a lateral force is applied to the tire, increase the rigidity of the bead portion, and maintain steering stability. For this purpose, the reinforcements j19A, 9B have a height H of their radial lower end
9ad and H9bd are set to be equal to or less than the height Hf of the lower point X1. The upper end has heights H9au and H9b that exceed the height H9 of the upper point x2, which is 0.25 times the tire cross-sectional height Hl.
Let it be u. Thereby, the reinforcing layers 9A and 9B are arranged over the area between the lower point X1 and the upper point X2.

Note that when the upper ends of the reinforcing layers 9A and 9B are smaller than the upper point X2, it becomes difficult to ensure the rigidity of the bead portion. Further, when the lower end is above the lower point X1, the reinforcing layers 9A and 9B are not present in the portion where the deformation is large and comes into contact with the rim flange 11 during deformation.
Decrease the rigidity of the front and back parts. Preferably, the position is located inside the tire radial direction from the separation point FP between the tire outer surface and the flange 11.

Further, the reinforcing layers 9A, 9B have their radially inner portions sandwiched between the bead apex 8 and the winding portion 6B. This causes the tensile force that acts upon deformation to be borne.

Further, due to such reinforcing layers 9A and 9B, the main body part 6A and the winding part 6B are arranged above the upper end of the bead apex 8 and radially outward of the lower point X1. Adjacent portions Y are formed in which these are adjacent to each other through the reinforcing layers 9A and 9B, that is, without intervening the bead apex 8.

Further, the heights H9a u - and H9b u are desirably smaller than the carcass height Hc, thereby reducing the stress caused by the reinforcing layers 9A and 9B terminating in the upper part of the sidewall part 3 which is highly deformed. Rubber ml due to concentration! is prevented.

Further reinforcement) 19A, 9B upper end and carcass winding part 6
It is also preferable that the upper ends of B are at the same position, since the difference in rigidity at this position is large, and damage due to concentration of stress, such as broken adhesion between the rubber and the cord at the end of the cord, breakage of the cord, etc., is likely to occur. No, or for similar reasons,
It is preferable that the upper ends of the reinforcing layers 9A and 9B do not coincide with each other, and in this example, the height H9au of the inner reinforcing layer 9A is set to be large.

As the cord material for the reinforcing layers 9A and 9B, organic fibers such as nylon and polyester, or metals can be used, but aromatic polyamide is preferably used because it has the same tensile rigidity as metal cords and is lightweight. I can do it. When aromatic polyamide cord is used, the cord size for passenger car tires is 720 d/2 to 3000 d/2.
The number of strands is about 25 to 45/5 tya, and the number of twists is about 20 to 70/10 cm. The cords of the reinforcing layers 9A and 9B are at an angle of 15 to 75 degrees with respect to the tire radial direction,
More preferably, the cords of the reinforcing layers 9A and 9B are arranged obliquely at an angle of 45 to 75 degrees, and the cords of the reinforcing layers 9A and 9B intersect with each other. With such a configuration, the rigidity of the door portion can be effectively increased.

Note that the tire 1 can also completely eliminate the bead apex 8, as shown in FIG.

At this time, the carcass 6 is rolled up around the bead core 5 from the inside in the axial direction to the outside at the winding part 6B.
are bent inward at the upper surface 5a of the bead core 5 in the tire radial direction, and the lower ends of each of the reinforcements N9k and 9B are in contact with and locked on the upper surface 5a of the bead core 5.

〔Concrete example〕

A pneumatic tire with a tire size of 185/60R14 was prototyped according to the specifications shown in Table 1, and compared with a conventional tire of the same size. The results are also shown in the same table.

All of the tires of the present invention were lighter in tire weight than the conventional products serving as comparative examples, and the results of various evaluations of maneuverability were also equal to or higher than those of the conventional products.

In addition, in Table 1, "the lateral spring constant J is determined from the amount of deformation of the tire and the magnitude of the lateral force when the tire is mounted on a regular rim, filled with the regular internal pressure, and lateral force is applied. can be,
r Lane Change Stability 1 is an evaluation of the vehicle stability based on the driver's feeling when the tires are installed on a domestic passenger car and the steering wheel is suddenly turned while driving straight at a speed of 1001/h. The convergence j is an evaluation of the subsequent stability of the vehicle based on the driver's feeling. is calculated from its speed.

〔Effect of the invention〕

In this manner, the tire of the present invention was able to reduce the weight of the bead portion without impairing handling stability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment, FIG. 2 is a sectional view showing another embodiment, and FIG. 3 is a sectional view illustrating a conventional technique. 2-) Red, 3--side wall, 4--bead section, 5--bead core, 6-carcass, 7
-.Belt, 8-.-Bead apex, 9A, 9B-Reinforcement layer, 10-.Rim.

Claims (1)

[Claims] 1. A toroidal main body extending from the tread part to a pair of bead cores via the sidewall part has a carcass integrally provided with a winding part for winding up the bead cores from the inside to the outside in the axial direction of the tire, and a bead base at the upper end of the winding part. The radial height from the line is 1/2 of the tire cross-sectional height.
and between the main body part and the winding part, including the area between the lower point which is the upper end of the rim flange and the upper point whose distance from the bead base line is 1/4 of the tire cross-sectional height. , a reinforcing layer made of a plurality of high-tensile cords is disposed, and the main body part and the winding part are adjacent to each other radially outward from the lower point with the reinforcing layer interposed therebetween. A pneumatic tire with adjacent parts.