JP5771408B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire excellent in durability of a bead portion of a tire.

Conventionally, as described in Patent Document 1, for example, in a tire bead portion, a hard rubber and a soft rubber are used in combination with a bead filler as shown in FIG. Tires have been proposed.
However, in the case of the tire structure shown in FIG. 1, since stress concentrates at point A in FIG. 1, separation is likely to occur, and there is a problem in bead durability.

JP 2008-94116 A

  However, when the rubber sheet B is inserted as an additional member as in Patent Document 2, there is a risk that productivity will deteriorate due to an increase in the number of members, and air C may enter the end of the sheet as shown in FIG. Such air entry tends to become a nucleus of crack generation, and there is a problem that it may lead to failure of the bead portion starting from this.

  Therefore, the present invention is to solve these problems, the purpose of which is to improve the structure of the bead portion of the tire, while achieving both steering stability and ride comfort, The object is to provide a pneumatic tire with improved bead durability.

  The inventors have made extensive investigations to solve the above problems, and in the tire width direction cross section, the soft rubber portion of the bead filler is V-shaped, and the hard rubber portion has a triangular cross section. In addition, the thickness of the outer side of the tire in the tire width direction of the bead filler of the soft rubber portion at the apex of the hard rubber portion at the outer side in the tire radial direction of the hard rubber portion is made thicker than the inner thickness of the tire. It is possible to improve the bead durability while achieving both of the above, to prevent the tire from collapsing when the tire collapses outward, and at this time, since no additional member is used, it is possible to prevent air from entering, and by increasing the number of members The knowledge that the increase in cost can be avoided was obtained.

A pneumatic tire according to the present invention is a carcass body portion straddling between a pair of bead cores in a toroidal shape, and is wound from the carcass body portion along the bead core from the inside in the tire width direction to the outside, at least in the tire radial direction of the bead core. A pneumatic tire comprising a carcass having a winding portion wound to the outer side surface, and having a bead filler having a triangular cross section in the tire width direction on the outer side in the tire radial direction of the bead core,
The bead filler has a triangular hard rubber portion whose bottom is disposed along the entangled portion in the tire width direction cross section, and whose apex opposite to the bottom is radially outward of the tire, and in the tire width direction cross section, Do and a rubber portion of the soft covering the two sides adjacent to the bottom of the rubber portion of the rigid Ri,
In the tire width direction cross section, the hard rubber portion has a shape in which an outer hypotenuse connecting the outermost point in the tire width direction of the bottom side and the apex is refracted into a triangular shape, and the hard rubber portion In the tire width direction cross section, the base has a shape that extends along the end of the entrainment portion, refracts inward in the tire width direction than the end, and directly contacts the bead core. To do.

In the tire according to the present invention, the soft rubber portion of the bead filler is V-shaped in the tire width direction cross section so that the soft rubber portion covers the hard rubber portion having a triangular cross section. The strain due to the stress between them can be alleviated, the separation can be prevented, and the bead durability can be enhanced. Further, by using both the hard rubber portion and the soft rubber portion, it is possible to achieve both steering stability and ride comfort.
Further, in the cross section in the tire width direction, by setting the thickness of the outer side of the tire with respect to the tire width direction of the soft rubber portion at the apex of the outer side in the tire radial direction of the hard rubber portion and the thickness of the inner side of the tire, It is possible to suppress the collapse when falling to the outside.
In addition, since a new member is not required in the present invention, it is possible to prevent air from entering without deteriorating productivity.

According to the present invention, it is possible to realize a tire that can achieve both steering stability and riding comfort and can prevent the tire from falling to the outside without using a new member that causes air entry or productivity deterioration. be able to.

It is sectional drawing of the conventional tire. It is sectional drawing of another conventional tire. It is sectional drawing of the tire by this invention in the case of a winding type bead structure. It is sectional drawing of the tire by this invention in the case of a folding | turning ply structure.

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 3 is a cross-sectional view in the tire width direction of a bead portion of a pneumatic tire (hereinafter referred to as “tire”) according to an embodiment of the present invention. As shown in FIG. 3, the tire has a bead portion 1a wound around the bead core 1 and the bead core 1 from the inner side to the outer side in the tire width direction and wound to the outer surface in the tire radial direction of the bead core 1, as shown in FIG. It has a bead structure with carcass 2. The bead portion further has a bead filler 6 having a cross-sectional triangle shape having a base 3 arranged along the winding portion 2a of the carcass 2 and an inner hypotenuse 5a and an outer hypotenuse 5b that intersect at the apex 4 facing the base 3. doing.
The bead filler 6 covers a hard rubber portion 6a having a triangular cross section having an inner hypotenuse 8a and an outer hypotenuse 8b that intersect at a base 3 and a vertex 7 facing the base 3, and an inner hypotenuse 8a and an outer hypotenuse 8b of the hard rubber portion 6a. It consists of a soft rubber part 6b.
At the vertex 7, the tire inner thickness t1 and the tire outer thickness t2 with respect to the tire width direction of the soft rubber portion 6b are set so that the tire outer thickness t2 is thicker.
Further, as shown in FIG. 3, a wire chafer 9, a nylon chafer 10, and a rubber chafer 11 are wound around the carcass 2 in this order as reinforcing materials.

  According to such a configuration, first, since hard rubber and soft rubber are used in the same manner as the bead portion of the conventional tire, the soft rubber increases the rigidity of the bead portion with hard rubber and improves the steering stability. By improving the ride comfort of the vehicle and balancing the two, it is possible to achieve both steering stability and ride comfort.

In addition, since the hard rubber portion 6a is covered with the soft rubber portion 6b, the carcass 2 does not directly contact the hard rubber portion 6a of the bead filler 6 on the inner side in the tire width direction. Since it is in contact with the rubber part 6b, the stress between the bead filler 6 and the carcass 2 can be relaxed, strain due to the stress can be relaxed, separation can be prevented, and bead durability can be improved.

Further, as shown in FIG. 3, at the apex 7, the tire outer thickness t2 with respect to the tire width direction of the soft rubber portion 6b is made thicker than the tire inner thickness t1, so that on the outer side of the tire that is easily affected by distortion. Distortion due to stress can be effectively prevented.
Further, when the tire is about to fall outside, the hard rubber portion 6a having high rigidity is close to the inside of the tire, so that the effect of supporting the falling toward the outside of the tire is enhanced.

Furthermore, in the conventional tire having a bead portion of the type shown in FIG. 2, a rubber sheet is used as a new member, and there is a concern about the deterioration of productivity and the entry of air. Since the bead part shown in 3 does not require a new member, such a defect is improved.

Further, in FIG. 3, the structure in which the carcass 2 is wound around the bead core 1 is taken as an example, but the present invention is not limited thereto, and in the case of the structure in which the carcass 2 is folded back from the inner side in the tire width direction. Can adopt the structure of the present invention. In this case, as shown in FIG. 4, in the bead portion of the tire including the carcass 2 having the folded portion 2b that is folded back from the inner side in the tire width direction along the bead core 1, the bottom 3 of the bead filler 6 is the bead core 1. 3 is different from the structure in the case of FIG. 3 in that the structure is arranged along the outer surface in the tire radial direction, but the other points are the same.
In the case of such a folded carcass structure, the same principle is used to achieve both steering stability and ride comfort, effectively preventing distortion due to stress on the outside of the tire that is susceptible to distortion, and to the outside of the tire. The effect of supporting the fall of the product is enhanced, and it is possible to avoid the deterioration of productivity and the entry of air.

Incidentally, in the present invention, the hard rubber portion 6a has a shape in which the outer hypotenuse 8b is refracted into a triangular shape as shown in FIGS.

Further, in the case of the type of structure in which the carcass of FIG. 3 has a winding portion, the hard rubber portion 6a has a bottom 3 extending along the winding portion 2a along the end of the winding portion 2a, and in the vicinity of the end, the bottom 3 Is refracted and directly touches the bead core 1 .
Similarly, in the case of the structure in which the carcass of FIG. 4 has a folded portion, the hard rubber portion 6a has a base 3 extending along an end in the tire width direction on the outer side in the tire radial direction of the bead core 1, and the end In the vicinity, the base 3 is refracted and has a shape in direct contact with the bead core 1 .

In order to form a bead filler using two types of rubber, hard rubber and soft rubber, a dual tuber, which is a composite extruder combining two single tubers, can be used.

Next, a test was performed to confirm that there is a difference in bead rigidity and bead durability between the tire of the prior art and the tire of the present invention.
Inventive example 1 is a tire of the type shown in FIG. 3, that is, a bead structure in which the carcass has a entangled portion, the bead filler has a V-shaped soft rubber portion, and the soft rubber portion has a triangular cross section. Further, a tire was manufactured as a trial in which the thickness t2 on the tire outer side in the tire width direction of the soft rubber portion at the apex 7 in FIG. 3 was larger than the thickness t1 on the tire inner side. Further, as Invention Example 2, the type of tire shown in FIG. 4, that is, a structure in which the carcass is folded from the inner side to the outer side in the tire width direction, the soft rubber bead filler is V-shaped, and the soft rubber part has a triangular cross section Further, a tire was manufactured in which the thickness t2 of the tire outer side in the tire width direction of the soft rubber portion at the vertex 7 in FIG. 4 was made thicker than the thickness t1 of the tire inner side.
As Comparative Example 1, a tire of the type shown in FIG. 2, that is, a tire in which soft rubber is embedded on the outer side in the tire width direction of the hard rubber and a rubber sheet is embedded on the inner side, was manufactured. Further, as Comparative Example 2, a tire of the type shown in FIG. 1, that is, a tire in which soft rubber was embedded on the outer side in the tire width direction of a hard rubber was prototyped.

  Tires with improved bead rigidity and bead durability can be manufactured and provided to the market.

1 Bead core
2 Carcass
2a Entrainment part
2b Folding part
3 Bottom
4 vertex
5a Inner hypotenuse
5b Outside hypotenuse
6 Bead Filler
6a Hard rubber part
6b Soft rubber part
7 Top of hard rubber part
8a Inside hypotenuse of hard rubber part
8b Outside hypotenuse of hard rubber part
9 Wayachefa
10 Nylon chafer
11 Rubber chafer
12 sidewall
A Stress concentration point
B Rubber sheet
C Air
D Refraction point
E Refraction point
t1 Thickness inside tire width direction at top of hard rubber part
t2 Thickness on the outer side in the tire width direction at the top of the hard rubber part
t3 Thickness inside tire width direction at refraction point D
t4 Thickness outside the tire width direction at refraction point D

Claims (3)

A carcass body portion straddling a pair of bead cores in a toroidal shape, and a winding portion wound from the carcass body portion along the bead core from the inner side to the outer side in the tire width direction and at least wound to the outer side surface in the tire radial direction of the bead core. A pneumatic tire having a bead filler having a triangular cross section in the tire width direction on the outer side in the tire radial direction of the bead core,
The bead filler has a triangular hard rubber portion whose bottom is disposed along the entangled portion in the tire width direction cross section, and whose apex opposite to the bottom is radially outward of the tire, and in the tire width direction cross section, It consists of a soft rubber part covering two sides adjacent to the bottom side of the hard rubber part,
In the tire width direction cross section, the hard rubber portion has a shape in which an outer oblique side connecting the outermost point in the tire width direction of the bottom side and the apex is refracted into a triangular shape ,
In the tire width direction cross section, the hard rubber portion has a shape in which the base extends along the end of the entrainment portion and is refracted on the inner side in the tire width direction than the end to directly contact the bead core . , Pneumatic tires. A carcass body portion straddling between a pair of bead cores in a toroidal shape, and a carcass having a turn-up portion that is folded back from the carcass body portion along the bead core from the inside in the tire width direction to the outside. A pneumatic tire having a bead filler having a triangular cross section in the width direction,
The bead filler, in a tire width direction cross section, a bottom is disposed along the tire radial outer surface of the bead core, and a triangular hard rubber portion whose apex facing the bottom is outward in the tire radial direction, and a tire width It consists of a soft rubber part covering two sides adjacent to the bottom side of the hard rubber part in the direction cross section,
In the tire width direction cross section, the hard rubber portion has a shape in which an outer oblique side connecting the outermost point in the tire width direction of the bottom side and the apex is refracted into a triangular shape ,
In the tire width direction cross section, the hard rubber portion extends along the tire width direction inner end of the bead core on the tire radial direction outer surface, and is refracted on the inner side in the tire width direction from the end. A pneumatic tire having a shape in direct contact with the bead core .   The tire inner thickness and the tire outer thickness with respect to the tire width direction of the soft rubber portion at the apex are set to be thicker on the tire outer side, according to claim 1 or 2. Pneumatic tire.

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