JPH0524412A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To provide reduction in the weight of a tire, and improve durability at a high speed driving, rotatability, and maneuvering stability. CONSTITUTION:A belt layer 9 which is disposed at the outside in the radius direction of a carcass 6 is divided into an inner belt layer body 10 which passes on a tire equator and a side belt layer body 11 which is disposed at the outside in a tire axial direction. The inner belt layer body 10 is formed from a belt ply piece which is made by winding a belt cord so as to incline at 0-5 degree to the tire equator in a spiral shape. The side belt layer body 11 are formed by an inner belt ply piece 11A which inclines at 15-25 degree to the tire equator and an outer belt ply piece 11B which is disposed outside of the belt ply piece 11A whose belt cords are arranged at the roughly same angle as the belt cord of the inner belt ply piece 11A and in a direction where the belt cord of the belt ply piece 11B crosses with the belt cord of the belt ply piece 11A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire which is excellent in high-speed durability and which is capable of improving steering stability while reducing tire weight.

[0002]

2. Description of the Related Art In recent years, radial tires having a belt layer wound around the outer side of a carcass and a tread portion reinforced have been widely used with the improvement of road networks and higher performance of vehicles. Further, the belt layer a is formed of a plurality of belt plies a1 and a1 which are generally high elastic cords made of steel or the like and are aligned in parallel with each other as shown in FIG.
The belt plies a1 are stacked in different directions so that the belt cords intersect each other between the plies. As a result, the belt cord cooperates with the carcass cord to form a strong truss structure, which exerts an excellent hoop effect and greatly enhances the tread rigidity.

On the other hand, in the tread portion of the tire, the shoulder portion is largely deformed during running. Therefore, in order to suppress this deformation, the belt ply is set wide such that both ends thereof extend to the vicinity of the shoulder. .

[0004]

However, in such a conventional belt layer, the belt cords cross each other and a plurality of belt plies are integrated to form a rigid shape, and the belt rigidity is remarkable in the center thereof. Become powerful. Therefore, when the tire flatness decreases, the tread surface a tends to have a backward warp r in which the center of the tread is concave, as shown in FIG. 4, and as a result, the vibration becomes large, the riding comfort is deteriorated, and the rolling performance is reduced. To worsen. Further, due to this reverse warp tendency, the contact pressure distribution also has a drum shape in which the shoulder portion is wider than the central portion, and uneven wear occurs between the shoulder portion and the central portion, impairing durability.

In such a wide and rigid belt layer, lateral force generated in the belt cord during cornering or when overhanging projections easily propagates to the entire ply, impairing handleability. The lateral force concentrates on the ply end, and it is easy to induce the peeling of the belt end.

In particular, in a tire having an aspect ratio of 75% or less, the above-mentioned tendency is conspicuous although the ground contact width is wide, and when a steel cord is used as a belt cord, the weight of the tire is increased while the high mass is increased. As a result, during high-speed traveling, lifting occurs in the belt layer, further reducing high-speed durability.

Therefore, in recent years, there has been a strong demand for a tire which is excellent in high-speed durability and is capable of enhancing steering stability and weight reduction.

The present invention divides the belt layer into an inner belt layer body and a side belt layer body, while the inner belt layer body is
An air which can solve the above-mentioned problems, based on the fact that one ply in which a belt cord is spirally wound and the belt layer body on the side are formed by two plies in which the belt cords cross each other between the plies. The purpose is to provide tires with rubber.

[0009]

In order to achieve the above object, a pneumatic tire of the present invention comprises a carcass folded around a bead core of a bead part from a tread part to a sidewall part, and a carcass of the carcass. A belt layer disposed radially outside and inward of the tread portion, and a belt layer body passing through the belt layer on the tire equator, and disposed on both outer sides of the inner belt layer body in the tire axial direction. The belt layer body is divided into a belt layer body on one side and a belt ply piece formed by spirally winding the belt cord at an angle of 0 to 5 degrees with respect to the tire equator. The belt layer body on the side is formed adjacent to the outside of the carcass and the belt cord is 15 to 25 with respect to the tire equator.
Formed by an inner belt ply piece that is inclined at an angle of 4 degrees and an outer belt ply piece that is placed on the outer side of the inner belt ply piece and that has belt cords arranged at substantially the same angle as the belt cord of the inner belt ply piece and in a direction that intersects is doing.

[0010]

In this way, the belt layer is divided into three regions, the inner belt layer body and the side belt layer body, and the inner belt layer body is formed by spirally winding the belt cord. Therefore, in the inner belt layer body, the tension of the belt cord effectively acts, and the necessary hoop effect can be maintained while reducing the number of cords to be driven, the number of plies, and the like, which improves rolling performance and prevents lifting accompanying high-speed rotation. At the same time, the weight of the tire can be reduced. Moreover, the cord arrangement by the spiral winding enhances the riding comfort such as moderately relaxing the rigidity in the width direction and makes the grounding pressure uniform, which improves the stability during straight running and prolongs the wear life.

Further, since the belt layer body on the side is formed by two belt ply pieces in which belt cords intersect each other, rigidity at the tread shoulder portion is increased, cornering force is increased, and steering stability is improved. To do.

Further, by dividing the belt layer, it is possible to prevent the stress generated in the belt cord from propagating in the width direction of the tread, improve the handling property, reduce the concentration of stress at the belt end and suppress the peeling of the belt end. .

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the figure, a pneumatic tire 1 has a tread portion 2,
A sidewall portion 3 extending inward in the tire radial direction from both ends thereof and a bead portion 4 located at an inner end in the tire radial direction of each sidewall portion 3 and reinforced by an annular bead core 5 are provided. Further, a toroidal carcass 6 extending along the tire inner cavity H is bridged between the bead portions 4 and 4, and a belt layer 9 is arranged radially outside the carcass 6 and inside the tread portion 2. To be done.

The carcass 6 is provided with folded-back portions 6B at which both sides of the bead core 5 are folded back from the inside of the tire to the outside of the main body portion 6A extending from the tread portion 2 to the bead portion 4 through the sidewall portion 3. The tip of the folded portion 6B is
There is a break near the maximum width position P of the tire. The carcass 6 has a carcass cord 70 to 9 with respect to the tire equator C.
It is formed from at least one carcass ply 6a arranged at an angle of 0 degree, and in this example, one carcass ply 6a. As the carcass cord, an organic fiber cord such as nylon, polyester, rayon or aromatic polyamide is preferably adopted. .

A relatively hard bead apex rubber 8 extending in a tapered shape from the bead core 5 toward the outer side in the tire radial direction is interposed between the main body portion 6A of the carcass 6 and the folded-back portion 6B. In addition to the high turn-up structure, the bead portion 4 to the sidewall portion 3 are reinforced and the tire lateral rigidity is enhanced. In this example, the bead apex rubber 8 has a height h from the bead base in the radial direction of the tire of 0.3 to the tire cross-section height H.
The reinforcing effect is further enhanced by providing a flipper 7 made of a reinforcing cord that is 0.5 times larger and surrounds the bead apex rubber 8 together with the bead core 5.

In the present invention, the belt layer 9 superposed on the outer side of the crown portion of the carcass 6 has a belt layer body 10 extending on the tire equator C and both of the belt layer bodies 10 in the axial direction of the tire. It is formed of a pair of left and right belt layer bodies 11 arranged on the outside. In this example, the belt layer 9 has a maximum belt width BW in the tire axial direction that is equal to the tread width TW.
The width of the tread portion 2 is 0.9 to 1.10 times larger than that of the tread portion 2 and has a low flatness of 0.75 or less.

The belt layer body 11 on the other side is, as shown in FIG. 2, an inner belt ply piece 1 adjacent to the outside of the carcass 6.
1A and an outer belt ply piece 11B to be placed on the outside thereof.
And a two-layer structure. Inner and outer belt ply pieces 11
A and 11B are each formed of a sheet-like body in which belt cords arranged in parallel with each other at an angle of 15 degrees or more and 25 degrees or less with respect to the tire equator C are embedded in a topping rubber, and the belt ply pieces 11A and 11B are As the belt cords cross each other between the plies, the belt cords are piled up in different directions.

Thus, the belt layer body 11 on the side can form a highly rigid truss structure by the intersection of the belt cords.
It is possible to increase the in-plane rigidity of the shoulder portion and increase the cornering force. In this example, one of the outer belt plies 11 is
The belt cord of B and the belt cord of the other outer belt ply 11B are inclined in symmetrical directions centering on the tire equator C, thereby suppressing the one-way flow of the vehicle due to the cord angle. .

In this embodiment, the inner belt ply piece 11A has a wider width than the outer belt ply piece 11B, and the inner and outer ends of the inner belt ply piece 11A are separated from the outer belt ply piece 11B in the tire axial direction. Project to.

The belt layer body 10 in the above is one endless belt formed by spirally winding a rubberized belt cord with respect to the tire equator C at an angle of 0 or more and 5 or less. The belt cord is composed of a ply piece 10A, and is continuously wound from one end of the belt ply piece 10A to the other end. Therefore, the belt layer body 10 can exert a necessary hoop effect while reducing the number of cords to be driven, can be reduced in weight, and can enhance rolling performance and effectively suppress lifting. Further, the belt layer body 10 can moderately relax the rigidity of the central portion of the tread by the spiral cord arrangement, enhance the riding comfort and equalize the ground contact pressure, and prevent the stress from propagating to the belt end. In addition to suppressing edge peeling, it improves handling.

Further, the inner belt layer body 10 has a width W1 larger than the distance between the inner ends of the belt layer body 11 on the side, whereby the outer end portion Q1 of the belt layer body 10 is on the side. The overlapping portion Q that overlaps the outer surface of the inner end portion Q2 of the belt layer body 11 is formed. Further, by forming such an overlapping portion Q, the lifting of the belt layer body 11 on the side is prevented, and the belt layer bodies 10 and 11 are organically bonded to each other, and the effect that each belt layer body 10 and 11 has To exert a good balance. For that purpose, the width W2 of the belt layer body 11 on each side is 0.15 times the maximum belt width BW or more and 0.1.
30 times or less, and the width W3 of the overlapping portion Q is 5 to
It is preferably 10 mm. When the width W2 is less than 0.15 times the maximum belt width BW, the cornering force is too small, and it is difficult to obtain a satisfactory effect of improving the steering stability. descend. Further, when the width W3 of the overlapping portion Q is smaller than 5 mm or there is no overlapping portion Q, the rigidity between the belt layer body 10 and the belt layer body 11 is locally reduced, the deformation in this portion is increased, and the tire is tired. The driving performance is greatly impaired. On the contrary, when the width W3 is larger than 10 mm, the rigidity in the overlapping portion Q becomes excessively large in steps, which causes abnormal wear in this portion and wastes the cost of materials and the like.

For the belt cord of the inner belt layer body 10 and the belt cord of the belt layer body 11 on the side, metal cords such as steel can be suitably adopted, and highly elastic organic fiber cords such as aromatic polyamide can be used. Can also be used upon request.

(Concrete Example) A tire having the tire structure shown in FIG. 1 and having a tire size of 185 / 70R14 was prototyped according to the specifications shown in Table 1, and the tire weight, steering stability, and straight running durability of the prototype tire were tested. Each sex was measured.

[0024]

[Table 1]

The measurement result at that time is 100 for the conventional tire.
Was compared using the index. The smaller the index, the lighter the tire weight, and the larger the index, the better the performance.

[0026]

As described above, in the pneumatic tire of the present invention, the belt layer is divided into three regions, the inner belt layer body and the side belt layer body, and the inner belt layer body is spirally wound by the belt cord. Since the belt layer body on the side and the belt layer body on the side are formed by the crossing structure of the belt cords, respectively, the weight of the tire can be reduced, high-speed durability and rolling performance can be improved, and steering stability can be improved.

[0027]

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a tire according to an embodiment of the present invention.

FIG. 2 is a schematic plan view showing a belt layer.

FIG. 3 is a schematic plane view for explaining a conventional belt layer.

FIG. 4 is a schematic cross-sectional view illustrating reverse warpage of a tire.

[Explanation of symbols]

2 tread section 3 Side wall part 4 bead section 5 bead core 6 carcass 9 Belt layer Belt layer in 10 10A Belt ply piece 11 side belt layer Belt ply pieces in 11A 11B Outside belt ply piece C tire equator Q1 inner end Q2 outer edge Q overlapping part

Claims (3)

[Claims] 1. A carcass folded from a tread portion to a sidewall portion around a bead core of a bead portion, and a belt layer arranged radially outside the carcass and inside the tread portion, and While dividing the belt layer into a belt layer body passing on the tire equator, and a belt layer body on the side arranged on both sides in the tire axial direction of the inner belt layer body,
The belt layer body in the above is formed by one belt ply piece formed by spirally winding the belt cord at an angle of 0 to 5 degrees with respect to the tire equator, and the belt layer body on the side is An inner belt ply piece that is adjacent to the outside of the carcass and in which the belt cord is inclined at an angle of 15 to 25 degrees with respect to the tire equator, and a belt cord of the inner belt ply piece that is placed on the outer side of the belt ply piece. A pneumatic tire formed by an outer belt ply piece arranged at substantially the same angle and in an intersecting direction. 2. The tire axially outer end portion of the inner belt layer body forms an overlapping portion which overlaps with the tire axially inner end portion of the side belt layer body. 1. The pneumatic tire according to 1. 3. The belt ply piece outside the belt layer body on the one side has its belt cord centered on the belt cord of the belt ply piece outside the belt layer body on the other side and the tire equator. The pneumatic tire according to claim 1, wherein the pneumatic tire is inclined in a symmetrical direction.