JP2010115957A - Bead part structure for pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bead part structure for a pneumatic tire capable of largely enhancing anti-removal out property of a carcass ply under the simple bead part structure. <P>SOLUTION: In the bead part structure, respective side part portions of the one sheet or more of carcass plies 2 comprising a ply cord 2a extending to be toroidal between a pair of bead parts are clamped between an inner half part 4 of the bead core 3 arranged at an inner surface side of the tire and an outer half part 5 arranged at an outer surface side of the tire. Each the inner half part 4 and the outer half part 5 of the bead core 3 is made to a wound structure formed by circumferentially winding bead wires 4a, 5a, and flat surfaces 4b, 5b contacted with the carcass ply 2 are provided on the bead wires 4a, 5a positioned adjacent to the side part portion of the carcass ply 2. Corner parts 4c, 5c are provided on an inner portion in a radial direction of the bead core of the flat surfaces 4b, 5b of the bead wire 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a bead portion structure of a pneumatic tire, and in particular, sandwiched between an inner half portion of the bead core disposed on the inner surface side of the tire and an outer half portion disposed on the outer surface side of the tire. We propose a technology that greatly improves the pull-out resistance of carcass plies.

  As a conventional bead portion structure of this type, there is one disclosed in Patent Document 1, for example.

This bead portion structure has a winding structure in which a bead wire having a substantially circular cross-sectional shape in the tire width direction is wound inside and outside in the radial direction, mainly in a spiral shape, and an inner half portion and an outer half portion of the bead core, In most cases, the side portions of the carcass ply are held between the bead wires and the carcass ply covering rubbers.
JP 2001-246910 A

  By the way, in such a conventional technique, each ply cord forming the carcass ply is merely point-contacted with the bead wire wound in a spiral shape at each inner half of the bead core, and the contact area between the two is small. Therefore, there is a problem in that the restraining force of the bead core with respect to the carcass ply is naturally reduced, and the pull-out resistance of the carcass ply cannot be denied.

  The present invention has been made to solve such problems of the prior art, and the object of the present invention is to withstand the pull-out resistance of the carcass ply under a simple bead structure. It is in providing the bead part structure of a pneumatic tire which can raise greatly.

  In the bead portion structure of the pneumatic tire according to the present invention, each side portion of one or more carcass plies made of a ply cord extending toroidally between a pair of bead portions is disposed on the inner surface side of the tire of the bead core. The inner half and the outer half arranged on the outer surface side of the tire are sandwiched between the inner half and the outer half, and bead wires, for example, spiral and spiral A winding structure that is wound in each form of the shape, and at least a part of the bead wire located adjacent to the side part of the carcass ply, more preferably the carcass ply, most of the covering A flat surface that is in contact with rubber is provided, and a corner or a protrusion is provided on a radially inner portion of the bead core of the flat surface of the bead wire. Than is.

  In such a bead portion structure, more preferably, at least a part of the bead wire located adjacent to the side portion of the carcass ply, the cross-sectional shape in the tire width direction, in other words, the contour shape in the meridian cross-section is a polygonal shape. Alternatively, a shape that is a combination of a curve and a string, such as a semicircular shape.

  In this case, the cross-sectional shape of each bead wire of the inner half portion and the outer half portion of the bead core is entirely formed of a single bead wire in the tire width direction. Sometimes it can be a polygonal shape or a shape that is a combination of a curve and a string over its entire length.

  In the bead portion structure of the pneumatic tire according to the present invention, each of the inner half portion and the outer half portion of the bead core contributing to the holding of the side portion of the carcass ply is positioned adjacent to the carcass ply side portion. A ply cord that forms a carcass ply on each bead wire by providing a flat surface that directly or indirectly contacts the carcass ply on at least a part of the bead wires, more preferably all of them. As a result, the contact area between the bead core and the carcass ply held by the bead core can be greatly increased as compared with the prior art, so that the restraining force of the carcass ply by the bead core is increased. The pull-out resistance of the carcass ply can be greatly improved.

In addition, here, when the tension in the pull-out direction acting on the carcass ply becomes particularly large and the carcass ply is relatively displaced radially outward of the bead core, the carcass ply is displaced radially outward. The torsional deformation that is accompanied by the displacement of the carcass ply is caused in the rotating bead wire of the bead core, which is blocked by the surrounding rubber or the like,
As a result, the corners or protrusions provided adjacent to the flat surface of each bead wire located across the carcass ply are displaced in a direction close to the carcass ply, that is, a direction to bite into the carcass ply, Since pulling out of the carcass ply is more firmly restrained, the pulling out resistance of the carcass ply can be improved more effectively.

  Thus, here, the pull-out resistance of the carcass ply can be effectively enhanced under a simple bead portion structure.

  Here, the cross-sectional shape in the tire width direction of at least a part of the bead wire located adjacent to the side portion of the carcass ply is combined with a curve and a string such as a polygonal shape or a semicircular shape. The bead wire itself has a simple structure and is inexpensive, with no special components, and the bead wire, and thus each half of the bead core, can function as expected. It can be demonstrated.

  Also, here, the cross-sectional shape in the tire width direction of each of the bead wires of the inner half portion and the outer half portion of the bead core is a polygonal shape or a shape that is a combination of a curve and a string over the entire half portion. When this is done, each of the inner half portion and the outer half portion can be simply configured by rotating one type of bead wire provided with a required flat surface in, for example, a spiral shape and a spiral shape. The required flat surface of the bead wire can be easily adjacent to the side portion of the carcass ply in a required posture.

  In contrast, when a required flat surface is formed only on a part of the entire length of the bead wire, or when a flat surface forming portion and a non-forming portion of the bead wire are joined to form a bead wire of a predetermined length, etc. However, it is difficult to make the required flat surface of the bead wire adjacent to the carcass ply in the expected posture, regardless of the configuration of the inner half and the outer half due to the bead wire.

  FIG. 1 is a sectional view in the tire width direction showing an embodiment of the present invention with respect to one bead portion, in which 1 is a bead portion and 2 is a ply extending toroidally between a pair of bead portions. One or more cords, one carcass ply is shown in the figure.

  Here, the carcass ply 2 corresponds to one side edge of the carcass ply 2 and the other side edge by crossing a large number of ply cords at a predetermined angle with respect to the tire equator plane. Can be formed by extending between each other, and one or a plurality of ply cords are folded in a U shape at the positions corresponding to the respective side edges described above, and zigzag in the circumferential direction. It can also be formed by extending a curved shape.

  Such side portions of the carcass ply 2 are, here, an inner half portion 4 located on the inner surface side of the tire and an outer half portion 5 located on the outer surface side of the tire of the bead core 3 disposed in the bead portion. Hold it between to prevent it from coming off.

  Although not shown in the drawings, this pneumatic tire has a tread portion having a general structure and a pair of sidewall portions continuous to the respective side portions of the tread portion, and the outer peripheral side of the crown portion of the carcass ply 2. And a belt that contributes to the reinforcement of the tread portion.

  In the meantime, as shown in FIG. 1, each of the inner half 4 and the outer half 5 is a wound structure in which one or more kinds of bead wires 4 a and 5 a are wound, and is adjacent to the side portion of the carcass ply 2. The bead wires 4a and 5a positioned at least partially, in the figure, the cross-sectional shape of all of them are rectangular, so that the main parts of the bead wires 4a and 5a are enlarged as illustrated in FIG. 2 is provided on the inner surface in the radial direction of the bead core 3 of each of the flat surfaces 4b and 5b of the bead wires 4a and 5a. Corner portions 4c and 5c are provided.

In addition, in the place shown in FIG. 1, the cross-sectional shape of the bead wires 4a and 5a located apart from the side part of the carcass ply 3 in each of the inner half part 4 and the outer half part 5 of the bead core 3 is circular. However, they can also be square.
In any of these cases, each of the contact portions and the non-contact portions of the respective half portions 4 and 5 with the carcass ply 2 circulates different types of bead wires that are independent from each other. In addition, it is also possible to configure both of these portions by rotating a continuous bead wire integrally. According to this latter, the inner and outer halves 4 and 5 can be more easily formed. -Can be configured quickly.

  Also, in the figure, the cross-sectional shape of the bead wires 4a and 5a having flat surfaces 4b and 5b having a quadrangular cross-sectional shape can be a polygonal shape other than a quadrangle, and combinations of various curves and strings. It can also be made into a shape.

  Further, by selecting such a wire cross-sectional shape, it is positioned adjacent to an arbitrary flat surface instead of the corners 4c and 5c that are necessarily formed at positions adjacent to the flat surfaces 4b and 5b. It is also possible to provide claw-like or other protrusions.

  According to the bead portion structure configured as described above, the carcass swallowed between the inner half portion 4 and the outer half portion 5 of the bead core 3 as illustrated in FIG. The side portion of the ply 2, particularly the ply cord 2a, is in direct line contact with the flat surfaces 4b and 5b of the bead wires 4a and 5a, mostly via a covering rubber. At this time, the ply cord 2a And the bead wires 4a and 5a are much larger than the point contact as described in the prior art, so that the restraining force of the carcass ply 2 by the bead core 3 is increased, and the carcass ply 2 The pull-out resistance is greatly improved.

  In this bead portion structure, when the carcass ply 2 is relatively displaced radially outward with respect to the bead core 3 due to a particularly large pulling force acting on the carcass ply 2, the bead wires 4a and 5a are Based on the holding force of the carcass ply and the vulcanized adhesive force of the covering rubber with the carcass ply 2, the bead wire itself is radiated by the rubber that embeds it, etc. Since the displacement in the direction is substantially prevented, the radial position is not changed together with the displacement of the carcass ply 2.

  However, each bead wire 4a, 5a in contact with the carcass ply 2 undergoes a torsional deformation due to a rotational moment in the transverse plane due to displacement of the carcass ply 2 in the pull-out direction. The corner portions 4c and 5c provided on the inner sides in the radial direction of the flat surfaces 4b and 5b of the bead wires 4a and 5a are both displaced in a direction close to the carcass ply 2 as illustrated by an imaginary line in FIG. Since the carcass ply 2 is more strongly held, further pulling displacement of the carcass ply 2 is more effectively prevented.

It is sectional drawing of the tire width direction which shows embodiment of this invention about one bead part. It is a principal part expanded sectional view which illustrates the effect | action of a bead wire.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bead part 2 Carcass ply 2a Ply cord 3 Bead core 4 Inner half part 4a, 5a Bead wire 4b, 5b Flat surface 4c, 5c Corner | angular part 5 Outer half part

Claims (3)

Each side part of one or more carcass plies made of a ply cord extending in a toroidal manner between a pair of bead parts, an inner half part arranged on the inner surface side of the bead core, and an outer side arranged on the outer surface side of the tire It is a bead structure of a pneumatic tire, which is held between the halves,
Each of the inner half portion and the outer half portion of the bead core has a winding structure in which a bead wire is wound, and at least a part of the bead wire located adjacent to the side portion of the carcass ply is a flat surface that contacts the carcass ply. And a bead portion structure of a pneumatic tire in which corners or protrusions are provided on a radially inner portion of the bead core of the flat surface of the bead wire.   The cross-sectional shape in the tire width direction of at least a part of the bead wire located adjacent to the side portion of the carcass ply is a polygonal shape or a shape that is a combination of a curve and a string. A pneumatic tire bead structure.   3. The cross-sectional shape in the tire width direction of each of the bead wires in the inner half portion and the outer half portion of the bead core is a polygonal shape or a shape that is a combination of a curve and a string as a whole. A pneumatic tire bead structure.

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