JP2001301417A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire allowing load durability and uniformity to be improved without drastically degrading productivity. SOLUTION: In this pneumatic tire, both ends 4A and 4B of a carcass layer 4 are wound from the inside to the outside of the tire around bead cores 5 built in right and left bead parts 3, and a belt layer 7 is disposed on the outer peripheral side of the carcass layer 4 in a tread part 1. Each of both ends 4A and 4B of the carcass layer 4 is extended to center region 1a of the tread part 1 through the inner peripheral side of the belt layer 7, winding ends 4a and 4b of the carcass layer 4 are formed in a recessed and projecting shape circumferentially of the tire, and the winding ends 4a, 4b formed in the recessed and projecting shape are engaged with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having a carcass layer mounted on left and right bead portions, and more particularly, to a pneumatic tire having improved load durability and uniformity without impairing productivity. For entering tires.

[0002]

2. Description of the Related Art Generally, a carcass layer of a pneumatic tire is composed of a rubber layer in which a large number of reinforcing cords are aligned and buried, and both ends of the carcass layer are wrapped around a bead core buried in right and left bead portions. , And the edge of the carcass layer having a large number of cut ends of the reinforcing cord is located at the tire side portion. Therefore, when a high load is applied to the tire, the tire side portion undergoes large repeated deformation, so that separation is likely to be induced at the edge of the carcass layer, and the load durability is poor. Further, since the presence of the cut ends of the reinforcing cords in the tire side portion has a bad influence on the uniformity, improvement of the uniformity has been left as an issue.

As a countermeasure, for example, there is a proposal of a carcass layer in which one reinforcing cord is continuously wound between left and right bead cores. By forming the reinforcing cords of the carcass layer in a continuous winding structure as described above, the problem of a large number of cut ends of the reinforcing cords is eliminated, so that load durability and uniformity can be improved. However, on the other hand, in the manufacturing process,
Since it is necessary to wind the reinforcing cord between the left and right bead cores on the forming drum and knit it, it takes time to manufacture,
There is a problem that productivity is greatly reduced.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic tire capable of improving load durability and uniformity without greatly reducing productivity.

[0005]

In order to achieve the above object, a pneumatic tire according to the present invention is characterized in that both ends of a carcass layer are wound around a bead core buried in right and left bead portions from the inside of the tire to the outside, and a tread is provided. In a pneumatic tire in which a belt layer is arranged on the outer peripheral side of the carcass layer in the portion, both end portions of the carcass layer are respectively extended to the center region of the tread portion through the inner peripheral side of the belt layer, and The winding end is formed in an uneven shape along the circumferential direction of the tire, and the uneven winding end is meshed with each other.

As described above, both ends of the carcass layer are respectively extended to the center region of the tread portion through the inner peripheral side of the belt layer, and the winding ends of the carcass layer are arranged in a region where large repeated deformation is unlikely. Suppress the occurrence of failures such as separation starting from the end,
Load durability can be improved. In addition, the winding end of the carcass layer is formed in an uneven shape along the tire circumferential direction, and the uneven winding end is engaged with each other. Therefore, even if a failure such as separation occurs, the failure is caused by the tire. It becomes difficult to progress in the circumferential direction, and the durability can be further improved.

Further, since the winding end of the carcass layer is concentrated on the center region of the tread portion which does not greatly affect the uniformity, the uniformity can be improved.

Further, since the carcass layer has a winding structure, when forming the carcass layer, it is sufficient to simply wind the sheet-like carcass layer around the bead core, and the productivity is not hindered.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows an example of the pneumatic tire of the present invention, wherein 1 is a tread portion, 2 is a sidewall portion, 3 is a bead portion, and CL is a tire center line. A carcass layer 4 in which a number of reinforcing cords extending in the tire radial direction are aligned and arranged between the left and right bead portions 3, and both end portions 4 A and 4 B sandwich a bead filler 6 around a bead core 5. In this way, the tire is wound up from the inside to the outside. Further, a plurality of belt layers 7 are arranged on the outer peripheral side of the carcass layer 4 in the tread portion 1.

Both ends 4A and 4B of the carcass layer 4 are shown in FIG.
As shown in the figure, the belt extends to the center region 1a of the tread portion 1 through the inner peripheral side of the belt layer 7. As shown in FIG. 3, the winding ends 4a and 4b of the carcass layer 4 are formed in an uneven shape along the tire circumferential direction. These uneven raised ends 4a and 4b correspond to the center region 1 of the tread portion 1.
a, they are arranged to mesh with each other, and are joined to each other. That is, the convex portion 4a ₁ of the one up end 4a is in contact with the recess 4b ₂ of the other winding end 4b, protrusion 4b ₁ of the other winding end 4b is in contact with the concave portion 4a ₂ of one of the up end 4a I have.

As described above, both ends 4A of the carcass layer 4
4B is passed under the belt and the center area 1 of the tread 1
a, and the raised ends 4a, 4b are not arranged in a region such as the sidewall portion 2 or the bead portion 3 which is subjected to large repeated deformation.
Can be improved in edge separation resistance and load durability can be improved. In addition, the raised ends 4a and 4b of the carcass layer 4 are formed in an uneven shape, and the uneven raised ends 4a and 4b are joined to each other by abutting each other. Therefore, when edge separation occurs, the edge separation occurs. It becomes difficult to move in the direction, and the durability can be further improved.

The winding ends 4a, 4a of the carcass layer 4
center area 1 where b does not greatly affect uniformity
a, so the uniformity (RF
V, LFV, CON, etc.).

In the pneumatic tire described above, since the carcass layer 4 has a rolled-up structure, in the manufacturing process,
It is sufficient to simply wind the carcass layer 4 around the bead core 5 without causing a significant increase in manufacturing time. Therefore, the productivity is not greatly reduced unlike the case where a single reinforcing cord is continuously wound between the left and right bead cores to form a carcass layer. Further, the carcass structure of the present invention, in which one carcass layer is wound up to below the belt to form substantially two carcass layers, is applied to a pneumatic tire in which conventionally two independent carcass layers are laminated. If applied, it is possible to reduce material costs and improve productivity while keeping the rigidity of the tire casing at the conventional level.

In the present invention, the concavo-convex shape of the raised ends 4a, 4b of the carcass layer 4 is such that both the concave portion and the convex portion are rectangular in FIG. 3, but instead of FIGS.
As shown in (b), the shape may be zigzag or wavy.

In the above-described embodiment, the unevenly wound ends 4a and 4b of the carcass layer 4 are arranged so as to abut each other and are joined to each other.
A and 4b do not always have to strictly abut each other, and the winding ends 4a and 4b may be arranged apart from each other as shown in FIG. In any case, the meshing width w of the uneven winding ends 4a, 4b is preferably set in the range of 10 to 80 mm. When the mesh width w is less than 10 mm, the effect of improving the durability becomes insufficient. The engagement width w is a width in which the convex portions 4a ₁ and 4b ₁ overlap when viewed from the tire circumferential direction T. Of course, it is desirable to set the mesh width w around the tire center line CL.

[0017]

EXAMPLE The tire size was made common to 195 / 65R15, both ends of the carcass layer were extended to the center region of the tread portion through the inner peripheral side of the belt layer, and the winding end of the carcass layer was extended along the tire circumferential direction. The tire of the present invention has the same structure as that of the present invention except that the tire of the present invention having the configuration shown in FIG. 1 is formed in an uneven shape, and the raised ends of the uneven shape are joined to each other, and the butt portion of the carcass layer is formed in a straight line. , A conventional tire 1 in which two carcass layers are rolled up so that the edges thereof are located at the sidewall portions, and a conventional tire in which a reinforcing cord of the two carcass layers is wound between bead cores to form a knitted structure. The tire 2 was manufactured.

Each of these test tires was rim size 15 × 6.
It was mounted on a JJ rim and subjected to load durability, uniformity, and productivity evaluation tests under the following measurement conditions. The results shown in Table 1 were obtained.

Load durability: After a load durability test was performed in accordance with JIS D4230, running was continued as it was, and a running distance until a failure due to separation occurred in the carcass layer was measured. The evaluation result was 100
And the index value. The larger the index value, the better the load durability.

Uniformity: Radial force variation (RFV) was measured according to the uniformity test method for automobile tires of JASO C607. The evaluation result was calculated using the reciprocal of the measured value, and
And the index value. The larger the index value, the better the uniformity.

Productivity: 50 test tires were molded at a time, and the molding time at that time was measured. The evaluation results were shown as index values using the reciprocal of the measured values, with the conventional tire 1 being 100. The larger the index value, the better the productivity.

[0022]

[Table 1]

As is apparent from Table 1, the tire of the present invention can improve load durability and uniformity without greatly reducing productivity.

[0024]

As described above, according to the present invention, both end portions of the carcass layer are extended to the center region of the tread portion through the inner peripheral side of the belt layer, and the winding end of the carcass layer is connected to the tire periphery. Since it is formed in an uneven shape along the direction and the winding ends of the uneven shape are engaged with each other, load durability and uniformity can be improved, and productivity is not significantly reduced.

[Brief description of the drawings]

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

FIG. 2 is an explanatory sectional view showing a main part of the pneumatic tire of the present invention.

FIG. 3 is a plan view showing a winding end of a carcass layer in the present invention.

FIGS. 4A and 4B are plan views each showing a modified example of a winding end of a carcass layer in the present invention.

FIG. 5 is a plan view showing another modified example of the winding end of the carcass layer in the present invention.

[Explanation of symbols]

1 tread portion 1a center region 2 sidewall portion 3 bead portion 4 carcass layer 4A, 4B both end portions 4a, 4b up end 4a _1, 4b ₁ projecting portion 4a _2, 4b ₂ recesses 5 bead core 7 belt layer CL tire center line w meshing width

Claims (3)

[Claims] 1. A pneumatic tire in which both ends of a carcass layer are wound up from the inside of the tire to the outside around a bead core embedded in left and right bead portions, and a belt layer is arranged on an outer peripheral side of the carcass layer in a tread portion. Both ends of the carcass layer are respectively extended to the center region of the tread portion through the inner peripheral side of the belt layer, and the winding end of the carcass layer is formed in an uneven shape along the tire circumferential direction. A pneumatic tire with winding ends meshed with each other. 2. The pneumatic tire according to claim 1, wherein the unevenly wound ends are joined by abutting each other. 3. An engaging width w of the uneven winding end.
The pneumatic tire according to claim 1 or 2, which has a diameter of 10 to 80 mm.