JPS60179309A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To prevent the slip-off of a bead and improve safety in traveling by forming a bead core by binding a plurality of bead wires having a circular section and arranging the prepared bead wires in a prescribed width in the direction of the inside diameter, forming the inside-diameter step difference. CONSTITUTION:An annular bead core BC is formed by integrally forming the inside and outside band-shaped bead cores 2 and 3 each of which is formed by binding a plurality of bead wires having a circular section in parallel so that a step difference is formed. The inside diameter difference (a) in the radial direction which is formed between the inside and outside cores 2 and 3 is set 0.3- 2.7mm., and the ratio b/c between the width (b) of the bead core on the projection side in the direction of inside diameter and the width (c) of the whole bead core is set to 0.2-0.8. With such constitution, the slip-off of the bead is prevented, and the safety in traveling can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention eliminates bead misalignment by selecting a specific shape from the conventional bead core.
This is a pneumatic tire that allows you to drive safely even if the air pressure of the tire decreases.

BACKGROUND ART Conventionally, in general, pneumatic tires are able to perform their original functions and enable safe driving only by filling them with a predetermined and sufficient air pressure. However, when the air pressure in the tire V decreases due to a puncture or other cause while driving, the bead that makes up the tire comes off (comes off) the bead seat on the rim, resulting in what is called a rim slip-off condition. It becomes easier. In this case, when the bead part comes off, the charged air pressure is instantaneously reduced, and the running vehicle not only loses control and cannot drive safely, but also becomes one of the causes of major car accidents.

This problem is on the rise as the speed of vehicle travel increases and the number of vehicles on the road increases. Therefore, there is an urgent need to develop a safe tire that will not dislodge its rim even under low pressure.

Conventionally, one of the methods for increasing resistance to this type of rim slipping and ensuring safe running of a vehicle is to increase the force when tightening the beads. This method is carried out by reducing the inner circumference of the annular bead core, but in this case, the force required to tighten the bead core is
The same force that applies to tightening the rim also acts on the tire vulcanization mold, and in the end, reducing the inner circumference of the annular bead core to prevent the rim from slipping off is the key to Green Tie V. It becomes difficult to insert into the vulcanization mold,
As a result, the tire is vulcanized under unstable conditions, which causes problems such as unevenness of the tire after vulcanization and vulcanization failure.

In order to solve the above-mentioned conventional problems, the inventor investigated various factors and found that there was a correlation between bead misalignment and the shape of the bead core. We focused on the fact that the bead of the tire that touches the rim has a taper, and after considering it, we found that in order to increase the low drag force that causes the tie V to slip off the rim without causing any problems, we decided to split the bead wire into two and create a stepped shape. This invention was achieved by reaching the conclusion that it was necessary to form a new structure.

In other words, the structure of the bead core of the present invention is such that a conventional bead core is formed by bundling a plurality of rubber-covered beads V in parallel and forming a ring shape to form one bead core. This one bead core is formed by shifting two band-shaped bead cores and joining them in an annular shape.In other words, multiple bead wires are bundled in parallel and formed into an annular shape with steps in the inner diameter direction. It is made into one bead core.

The degree of this shift is determined by the inner diameter difference a, as shown in FIG.
-Q, it is formed to be shifted within the range of 3 to 2.7 mm, but there may be cases where no step is provided at the outer peripheral portion. The most preferable inner diameter difference a is about 0.3 to 1.6 nun. Also, the width b of the protruding side lower core in the inner diameter direction
and the overall bead core width C: b/c = 0.2 to 0.
It is formed in a range of about 8.

If a is less than 0.3, the rim at the throat will not have enough resistance to slipping, and if it exceeds 2.7 mm, problems will occur with poor tire uniformity and an increase in vulcanization failures. Further, if the width ratio b/C is less than 0.2, the resistance force of the bead core becomes unstable, and if it exceeds 0.8, it is accompanied by an increase in tire uniformity defects and vulcanization failures.

Next, aspects of the present invention will be described in detail based on the drawings.

Figure 1 shows a cross section of an example of the annular beat core 8C of a conventional pneumatic retiring hair.This figure shows five layers of B1 to Y71 arranged in parallel and stacked in five layers. A bead core of 1 g was formed by
It is customary to be covered with rubber.

Fig. 2 shows a cross section of an example of the annular bead core BC of the pneumatic tire of the present invention. Two belt-shaped bead cores 7 are formed in a stepped shape in the inner diameter direction to form one bead core BC.

In the figure, a is the dimension of the inner diameter difference, 1 is the bead wire, 2 is the inner strip-shaped bead core, 3 is the outer strip-shaped bead core, C is the overall width of the bead core, and b is the width of the protruding side bead core in the inner diameter direction. be. Therefore, b/C is the ratio of the width of the protruding bead core to the overall width.

As described above, unlike the conventional method of reducing the entire circumference of one bead core by forming one bead core in a stepped state in the inner radial direction and changing the circumferential length, it is possible to reduce tire uniformity defects. The bead core can be tightened with force without any problems such as vulcanization failure.
This is because the tire rim increases its resistance to slippage.

The rim shear resistance force referred to here is the internal air pressure at the time of maximum rim shear when a block is pressed from the side with a constant load against the tire set on the rim. Uniformity (LFV) is the Japanese Automobile Standards and Technology Association (JAS).
This is the magnitude of the variation in the lateral force generated on the tire contact surface, measured based on the method specified in JASOC607 of (O).

FIG. 3 shows the use of the bead core shown in FIG. 2 of the present invention.
Figure 4 shows the relationship between the size of the inner diameter difference a and the rim shear resistance force (index) when the width ratio is 1), / C = Q, 5. A curve shows the relationship between the size of the inner diameter difference a and the uniformity (index) when =Q, 5.

In Figure 3, the horizontal axis shows the size of a(lIllll), the vertical axis shows the rim shear resistance index, and in Figure 4, the horizontal axis shows a(nv
), and the vertical axis shows the L F V index. As the curve in the figure shows, the rim shear resistance is insufficient when a = less than 0.3; =1.6+
It rises rapidly to around u, then gradually decreases to around 2111111, and slowly increases to around 3 mm.
It is something that Therefore, the usable range is 0.3 to 2.7
Although it is about n+Ill, the most preferable range when uniformity is also considered is about 0.3 to 1.6 mm. Further, uniformity r(1-FV) is a=1.
This shows a tendency to gradually increase from near 5n+n+iri.

Figure 5 shows the width ratio b/C when the inner diameter difference a = 1.3 + va.
Figure 6 shows the relationship between the width ratio b/c and the uniformity (index) when the inner diameter difference is a -1.3 mm. This is a curve showing.

Figure 5 shows the magnitude of b/c on the horizontal axis, the rim shear resistance index on the vertical axis, and Figure 6 shows the magnitude of b/c on the horizontal axis, and the uniformity (LFV) on the vertical axis. ) indicates the index,
As shown in the curve in the figure, when b, /c is less than 0.2, the resistance of the bead core BC is insufficient, and when b/c exceeds 0.8, the tire's unif A midi increases rapidly and deteriorates. It is something to do.

In particular, it is appropriate to select b,/c=Q, within a range of about 2 to 0.8.

In addition, as shown in each of the above drawings, /c=0.5, a=1.
Even if the value of 3111m is changed, the tendency of the effect is the same. Furthermore, the influence of the inner peripheral length of the bead core is also favorable.

FIG. 7 shows 1. of the pneumatic tie V of the present invention. /2 sectional view, 4 is a carcass ply, and BC is a stepped bead core of the present invention.

As described above, the pneumatic tire of the present invention does not cause defects such as poor uniformity or vulcanization failure.
The tightening of the bead exerts force and increases the resistance of the tire rim to slipping, which is a feature that is essential for safe driving.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a bead core of a conventional pneumatic tie 7, FIG. 2 is a sectional view of an example of a bead core of a pneumatic tire of the present invention, and FIG. 3 is a sectional view of an example of a bead core of a pneumatic tire of the present invention. Figure 4 is a UNIF A MIDI curve diagram for the inner diameter difference. Figure 5 is a rim shear resistance curve diagram for the width ratio (b/c). Figure 6 is the width ratio (b/c). Figure 7 is a 1/2 sectional view of pneumatic tie A7 in which an example of the bead core of the present invention is set. 1... Bead wire 2... Inner band-shaped bead core 3 ... Outer band-shaped bead core a ... Inner diameter difference b ... Width of the protruding bead core in the inner diameter direction C ... Overall paddle of the bead core t+, /c ... Width ratio BC ... Bead core substitute Person Patent Attorney Yasuho Oshima Figure 2 Figure 3 Figure 5 Figure 4 Figure 6 Figure 7 Voluntary procedure amendment June 8, 1982 Display of 1.91 1982 Revised Patent Application No. 34850 2 , name of the invention (pneumatic tie) 7 3. Relationship with the case of the person making the amendment Patent applicant 1-17-18 Edobori, Nishi-ku, Osaka-shi, Osaka (314)
Toyo Tire & Rubber Industries Co., Ltd. Representative Souji Matsuoka 4, Sototo 550 1-25-30 Edobori, Nishi-ku, Osaka City Detailed explanation column and drawings of the invention in the specification. 6. Contents of amendment (1) From page 6, line 20 of the specification to page 7, line 1, “
``Using the bead core shown in FIG. 2 of the present invention'' is amended to ``Regarding the tire using the bead core of the present invention''. (2) Figure 5 attached to the specification shall be amended as shown in Figure 5 attached to the attached sheet. that's all

Claims (1)

[Claims] (1) In a pneumatic tire in which the carcass ply ends are wound around an annular bead core, a plurality of bead wires with a circular cross section are bundled in parallel. One bead wire is used, and the inner diameter difference a of the stepped bead core in the cross section passing through the tie\7 axis is 0.3 to 2.7 m.
1a, and the ratio of the width b of the protruding side door core in the inner diameter direction to the overall width C of the door core, /c, is set to 0.
A pneumatic tire characterized by having a particle diameter in the range of 2 to 0.8.