JPH0516620A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To provide a pneumatic tire which has a specific excellent rim removal resisting property constantly regardless of the size and the structure of the tire. CONSTITUTION:In a pneumatic tire in which a bead core 1 made by collecting plural bead wires 2 is buried in a bead, the bear core 1 is composed of small bead cores 1a and 1b divided in the tire width direction, and a rubber layer 3 of the JIS hardness 85 to 95 placed between the small bead cores 1a and 1b. Such a pneumatic tire is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire which has a certain excellent rim detachment resistance regardless of the difference in tire size and structure, and is suitable for passenger cars. Containing tires.

[0002]

2. Description of the Related Art Generally, a bead core of a pneumatic tire is composed of a bundle of a plurality of bead wires. The number of bead wires is different depending on the tire size and the structure for normal running, high speed running, etc., and the gauge around the bead core is also changed accordingly, so it is different. Is becoming

On the other hand, the rim for mounting the tire has a rim size of a normal rim for a passenger car.
For 4 1/2 J or larger, the base width is 22 mm, which is constant according to the standard. For this reason, when tires having different bead widths are mounted as described above, there is a problem in that the fitting force is different and the rim detachment resistance is not constant depending on the tire.

That is, the bead width tends to be smaller than the rim base width with the recent improvement in the characteristics of reinforcing materials such as wires and cords. However, such a bead portion having a narrow bead width has a constant rim base width. When attached to the rim,
If the seat is badly seated or if the distance between the inner end of the rim base and the hump is very large, the rim base is apt to be displaced inward, and the tightening force is not constant, which causes the fitting force to be easily reduced.

However, if the number of bead wires is increased to widen the width of the bead core as a countermeasure, the weight is increased, or the number of bead wires is kept the same and the number of arranged wires in the vertical direction is reduced to increase the width. Increasing the number of arrangements in (3) reduces the circumferential rigidity of the bead core, so it was not an essential solution.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic tire having a constant and excellent rim resistance regardless of the difference in tire size and structure.

[0006]

Means for Solving the Problems The present invention for achieving the above object provides a pneumatic tire in which a bead core having a plurality of bead wires bundled therein is embedded in a bead portion, wherein the bead core is divided in the tire width direction. A small bead core and JI interposed between the divided small bead cores.
It is characterized by comprising a rubber layer having an S hardness of 85 to 95.

As described above, since the bead core is constructed by interposing the rubber layer having the JIS hardness of 85 to 95 between the two small bead cores, the bead width is adjusted by adjusting the width of the rubber layer. Can be adapted to. Therefore, it is possible to set the bead width that optimizes the fitting force regardless of the tire size and structure, and it is possible to prevent the rim from coming off.

The tire of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a meridional direction sectional view showing an example of a bead portion of a tire of the present invention. Reference numeral 1 denotes a bead core, and the end portion of the carcass layer 6 is folded back around the bead core 1 from the tire inner side to the outer side so as to wrap the bead filler 4. The bead core 1 is composed of two small left and right small bead cores 1a and 1b divided into two in the tire width direction, and a rubber layer 3 interposed between the two small bead cores 1a and 1b. Reference numeral 5 is a rim on which the bead portion is mounted, and reference numeral 5a is a hump thereof. This hump 5a
Defines the bead base width RW.

In the bead core 1 constructed as described above, the rubber layer 3 is provided for adjusting the bead width BW, and its hardness is set within the range of JIS hardness 85 to 95. If the rubber hardness is softer than JIS hardness 85, the rigidity of the bead core cannot be secured, and it becomes difficult to maintain good rim detachment resistance. If the hardness is higher than JIS hardness 95, the rubber itself is likely to be damaged, which is not preferable.
The rubber layer 3 may be formed alone or may be formed integrally with the bead filler 4.

The two small bead cores 1a and 1b on the left and right sides must be arranged at both the left and right ends of the bead core 1 so as to directly support the tension of the carcass layer 3.
In this way, the number of constituent wires of the bead wires 2 of the small bead cores 1a and 1b arranged on the left and right sides should be the same.
Alternatively, the small bead cores 1a inside the tire may be distributed more than the small bead cores 1b outside. This is because the tension of the carcass layer 3 is applied more to the inside than the outside of the tire. For example, if the total number of bead wires required in the design is length × width = 5 × 4 = 20, then both small bead cores 1a and 1b are distributed by 5 × 2, and the required total number is 5 × 5. = 25, 5 × 3 = 15 in the small bead core 1a inside the tire, and 5 × 2 = 10 in the small bead core 1b outside the tire.

Further, the small bead cores 1a, 1b arranged as described above preferably have their inner diameters Da, Db in a relationship of Db ≧ Da. When the relationship of Db> Da is established as shown in FIG. 2, the taper angle of the bead sheet should be parallel to this, so that the pressure applied to the bead portion can be made constant. Small bead cores 1a, 1b
It is desirable that the difference between the inner diameters Da and Db of 0 is in the range of 0 to 8 mm. If it is larger than 8 mm, the rigidity on the bead heel side will be reduced, resulting in poor fitability.

Further, when the small bead cores 1a and 1b are constructed by splicing the bead wire for one round of the tire, it is preferable that the splices are evenly distributed to a plurality of locations on the circumference of the tire. The tires are preferably arranged in four equal parts, which can improve the uniformity of the tire. Small bead core 1 as described above
The bead width of the bead portion adjusted by disposing a rubber layer between a and 1b is preferably 14.0 to 16.5 mm. By setting in such a range, it becomes possible to maintain a good fitting property with respect to a rim having a rim base width of 22 mm.

[0013]

Example: The tire size is 195 / 65R15 90
Use H to set the number of bead wires that make up the bead core to 3
The tires of the present invention and the comparative tires 1 and 2 having different bead core configurations as described below except that the number of tires is 0
Was prototyped. The tire of the present invention: -Bead core configuration: Fig. 1 (separation structure) Small bead core inside tire ... 6 x 3 (length x width) Small bead core outside tire ... 6 x 2 (length x width) Rubber layer-・ ・ JIS hardness 90, width = 3 mm ・ Bead width BW = 16.5 mm Comparative Example 1: ・ Structure of bead core: single structure Bead wire arrangement: 6 × 5 (length × width) ・ Bead width BW = 16 .5 mm Comparative Example 2: ・ Bead core configuration: single structure Bead wire arrangement: 6 x 5 (length x width) ・ Bead width BW = 13.5 mm These three types of tires are each equipped with an axle rim (15).
X6JJ), and with the internal pressure of 2.0 kg / cm ² enclosed, a flat plate having a 5 ° inclination with respect to the axle is brought into contact with the shoulder portion on one side as shown in FIG. Three different levels of force (800kg, 600k)
(g, 400 kg), the tire internal pressure (kgf / cm ² ) was measured when air began to leak from the rim fitting part when the tire internal pressure was gradually reduced, and the results shown in Table 1 were obtained. It was The lower the internal pressure when air leakage starts, the better the fitting property and the better the rim detachability.

[0014] As can be seen from Table 1, in the tires of the present invention, the internal pressure when air leakage starts is lower than that of the comparative tires 1 and 2, and the rim detachment resistance is improved.

[0015]

As described above, according to the present invention, the JIS hardness is 85 to 95 between the two small bead cores.
Since the bead core is formed by interposing the rubber layer described above, the bead width can be adapted to the rim base width by adjusting the width of the rubber layer. Therefore, it is possible to set the bead width that optimizes the fitting force regardless of the tire size and structure, and it is possible to prevent the rim from coming off.

[Brief description of drawings]

FIG. 1 shows a part of a meridional direction cross section showing the vicinity of a bead portion when an example of a pneumatic tire of the present invention is mounted on a rim.

FIG. 2 shows a part of a meridional section showing a vicinity of a bead portion when a pneumatic tire according to another embodiment of the present invention is mounted on a rim.

FIG. 3 is a cross-sectional view showing a method of measuring a tire internal pressure by placing a shoulder portion on one side of a tire on a flat plate having an inclination.

[Explanation of reference symbols] 1 bead core 1a, 1b small bead core 2 bead wire 3 rubber layer

Claims (1)

Claims: 1. A pneumatic tire in which a bead core in which a plurality of bead wires are bundled is embedded in a bead portion,
A JI in which the bead core is interposed between the small bead cores divided in the tire width direction and the divided small bead cores.
A pneumatic tire composed of a rubber layer having an S hardness of 85 to 95.