JP2007008406A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of preventing failure due to a reinforcing layer of a bead portion, and improving durability. <P>SOLUTION: At least one layer of carcass plies 4a, 4b wherein a reinforcing cord has a tilting angle in a tire diametrical direction is laid between a pair of the bead portions 3, 3. A bead core 5 and a bead filler 6 are buried in each bead portion 3. The reinforcing layer 8 extending to a position outside in the tire diametrical direction more than the apex of the bead filler 6 and wherein the reinforcing cord has the tilting angle in the tire diametrical direction is disposed between the outermost carcass ply 4b and the bead filler 6. A tilting direction of the reinforcing cord of the reinforcing layer 8 is made to be the same direction of the reinforcing cord of the carcass ply 4b on the outermost side. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pneumatic tire in which a reinforcement layer is embedded in a bead portion, and more particularly to a pneumatic tire that can prevent a failure due to the reinforcement layer of the bead portion and improve durability.

In a pneumatic tire, in order to increase the rigidity of the bead portion, a reinforcing layer made of a reinforcing cord is disposed along the carcass ply (see, for example, Patent Document 1). In the case of radial tires, the reinforcing cord of the carcass ply extends in the tire radial direction, and there is no change in the angle of the reinforcing cord of the carcass ply in the vulcanization molding process. Therefore, even if the reinforcing layer is arranged adjacent to the carcass ply There is no particular inconvenience. However, in the bias tire, the carcass ply reinforcement cord has an inclination angle with respect to the tire radial direction, and the angle change occurs in the carcass ply reinforcement cord in the vulcanization molding process. As a result, there is a problem that failure due to the reinforcing layer embedded in the bead portion is likely to occur, and the durability of the tire is reduced.
JP 2003-320819 A

  An object of the present invention is to provide a pneumatic tire capable of preventing a failure due to a reinforcing layer of a bead portion and improving durability.

  In order to achieve the above object, a pneumatic tire according to the present invention includes at least one layer of a carcass ply in which a reinforcing cord has an inclination angle with respect to a tire radial direction, and a bead core disposed between each pair of bead portions. In the pneumatic tire in which the bead filler is embedded, the outermost carcass ply and the bead filler extend between the outermost carcass ply and the bead filler to a position on the outer side in the tire radial direction, and the reinforcing cord extends in the tire radial direction. A reinforcement layer having an inclination angle is disposed, and the inclination direction of the reinforcement cord of the reinforcement layer is set in the same direction as the reinforcement cord of the outermost carcass ply.

  As a result of earnest research on the mutual interference between the reinforcing layer embedded in the bead portion and the carcass ply in the pneumatic tire having the bias structure or the half radial structure, the inventor has determined that the inclination direction of the reinforcing cord of the reinforcing layer is the outermost side. When the reinforcing layer is disposed in a direction opposite to the reinforcing cord of the carcass ply and extends between the outermost carcass ply and the bead filler so as to extend to a position radially outside the apex of the bead filler, The effect of the change in the angle of the reinforcement cord of the ply acts only on the portion of the reinforcement layer protruding from the bead filler, and the reinforcement layer is buckled near the top of the bead filler, causing a failure starting from the buckled portion. It has been found that it becomes easy, and the present invention has been achieved.

  That is, in the present invention, in a pneumatic tire having a bias structure or a half radial structure, the tire extends between the outermost carcass ply and the bead filler to a position radially outside the apex of the bead filler. In the vulcanization molding process, a reinforcing layer having a reinforcing cord with an inclination angle with respect to the radial direction is arranged, and the reinforcing cord is inclined in the same direction as the reinforcing cord of the outermost carcass ply. It is possible to avoid the reinforcement layer from buckling near the apex of the bead filler when the angle change occurs in the reinforcement cord of the ply. Thereby, the failure resulting from the reinforcing layer embedded in the bead portion can be prevented, and the durability of the pneumatic tire can be improved.

  In the present invention, the inclination angle of the reinforcing cord of at least one layer of the carcass ply with respect to the tire circumferential direction is preferably 30 ° to 85 °. On the other hand, the inclination angle of the reinforcing cord of the reinforcing layer with respect to the tire circumferential direction is preferably 30 ° to 90 °. Furthermore, the intersection angle on the narrow angle side between the reinforcement cord of the outermost carcass ply and the reinforcement cord of the reinforcement layer is preferably 60 ° or less.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a pneumatic tire according to an embodiment of the present invention. In FIG. 1, 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. As shown in FIG. 1, two layers of carcass plies 4 a and 4 b are mounted between one bead portion 3 and the other bead portion (not shown), and the end portions of these carcass plies 4 a and 4 b are connected to the bead core 5. Around the tire is folded from the inside to the outside. Each of the carcass plies 4a and 4b includes a plurality of reinforcing cords that are aligned, and the reinforcing cords have an inclination angle with respect to the tire radial direction. Further, the carcass plies 4a and 4b are arranged so that the inclination directions of the reinforcing cords are opposite to each other. A bead filler 6 made of high-hardness rubber is disposed on the outer periphery of the bead core 5, and the bead filler 6 is wrapped by folded portions of the carcass plies 4a and 4b. On the other hand, a breaker 7 is disposed on the outer periphery side of the carcass plies 4a and 4b in the tread portion 1 over the entire circumference of the tire.

  In the pneumatic tire, between the outermost carcass ply 4 b and the bead filler 6, a reinforcing layer 8 that extends to a position radially outside the apex of the bead filler 6 is disposed. The reinforcing layer 8 includes a plurality of aligned reinforcing cords, and the reinforcing cords have an inclination angle with respect to the tire radial direction. The inclination direction of the reinforcing cord of the reinforcing layer 8 is the same direction as the reinforcing cord of the outermost carcass ply 4b.

  FIG. 2 schematically shows a carcass ply assembled on a forming drum and a reinforcing layer of a bead portion in plan view in order to obtain the pneumatic tire of the present invention. In FIG. 2, C1 is the reinforcement cord of the outermost carcass ply, and C2 is the reinforcement cord of the reinforcement layer embedded in the bead portion. E is a tire equator line, a direction perpendicular to the tire equator line E is a tire radial direction, and a direction parallel to the tire equator line E is a tire circumferential direction. As shown in the drawing, when the inclination direction of the reinforcing cord C2 of the reinforcing layer is the same as that of the reinforcing cord C1 of the outermost carcass ply, the reinforcing cord C1 of the outermost carcass ply in the vulcanization molding process has a broken line C1 ′ as shown in FIG. When the angle change occurs, the reinforcing cord C2 of the reinforcing layer changes the angle together with the reinforcing cord C1 of the outermost carcass ply. As a result, as shown in FIG. 3, the reinforcing cord C2 is in a favorable arrangement state in the obtained pneumatic tire.

  On the other hand, as shown in FIG. 4, when the inclination direction of the reinforcing cord C2 of the reinforcing layer is opposite to the reinforcing cord C1 of the outermost carcass ply, the reinforcing cord C1 of the carcass ply has a broken line C1 ′ in the vulcanization molding process. When such an angle change occurs, the reinforcing cord C2 of the reinforcing layer is pushed in the longitudinal direction. As a result, as shown in FIG. 5, the reinforcing cord C <b> 2 is buckled near the apex of the bead filler 6 in the obtained pneumatic tire.

  That is, a reinforcing layer that extends between the outermost carcass ply 4b and the bead filler 6 to a position outside the apex of the bead filler 6 in the tire radial direction and has a reinforcing cord with an inclination angle with respect to the tire radial direction. When the angle of the reinforcing cord of the carcass ply is changed in the vulcanization molding process, the reinforcing cord 8 is arranged in the same direction as the reinforcing cord of the outermost carcass ply 4b. The reinforcement layer 8 can be prevented from buckling in the vicinity of the apex of the bead filler 6, and as a result, failure due to the reinforcement layer 8 of the bead portion 3 is prevented and the durability of the pneumatic tire is improved. Can do.

  As shown in FIG. 2, the inclination angle θ1 of the reinforcement cord C1 of the outermost carcass ply with respect to the tire circumferential direction is preferably 30 ° to 85 °. On the other hand, the inclination angle θ2 of the reinforcing layer with respect to the tire circumferential direction of the reinforcing cord C2 is preferably 30 ° to 90 °. Further, the crossing angle θ3 on the narrow angle side between the reinforcing cord C1 of the outermost carcass ply and the reinforcing cord C2 of the reinforcing layer is preferably 60 ° or less. The present invention is particularly effective when the inclination angles θ1, θ2, and θ3 are as described above. These inclination angles θ1, θ2, and θ3 are angles measured at the center position of the bead filler in the tire radial direction.

  The reinforcing cords of the carcass ply and the reinforcing layer are preferably organic fiber cords. Examples of the organic fiber cord include nylon cord, polyester cord, rayon cord, and aramid cord that are usually used in the tire industry.

  In the above-described embodiment, the pneumatic tire having two layers of carcass plies has been described. However, the present invention can be applied to a pneumatic tire having at least one layer of carcass plies, and includes an outermost carcass ply and a bead. By relaxing the mutual interference with the reinforcing layer embedded in the part, it is possible to ensure good durability while obtaining the effect of increasing the rigidity based on the reinforcing layer.

  The outermost carcass ply in a pneumatic tire in which two layers of carcass plies whose reinforcement cords are inclined with respect to the tire radial direction are mounted between a pair of bead parts, and each of the bead parts is embedded with a bead core and a bead filler. A reinforcing layer that extends to a position on the outer side in the tire radial direction from the apex of the bead filler and between which the reinforcing cord has an inclination angle with respect to the tire radial direction, and the reinforcing cord of the reinforcing layer Example tires and comparative tires having different inclination directions were produced. The tire structures of these examples and comparative examples are shown in Table 1. The tire size was 225 / 50R16.

  The durability of these test tires was evaluated by the following test method, and the results are shown in Table 1. In addition, the state of the reinforcing layer embedded in the bead portion was examined, and the presence or absence of buckling in the vicinity of the apex of the bead filler was confirmed.

durability:
After running the test tire on a drum with a diameter of 1707 mm for 24 hours under conditions of air pressure of 180 kPa, load of 4 kPa, and speed of 80 km / h, the load was increased by 15% every 4 hours until the tire failed. The distance was measured. The evaluation results are shown as an index with the comparative example as 100. The larger the index value, the better the durability. In addition, after the test, the destruction location and the destruction state were also investigated.

  As shown in Table 1, the durability of the tire of the example was significantly improved as compared with the comparative example. In particular, in the tire of the example, the fractured portion was present inside the bead filler, and no failure due to the reinforcing layer was observed.

It is a meridian half section view showing a pneumatic tire according to an embodiment of the present invention. It is a top view which shows roughly the reinforcing layer of the carcass ply and bead part assembled on the molding drum in order to obtain the pneumatic tire of this invention. It is sectional drawing which shows roughly the arrangement | positioning state of the reinforcement layer in the pneumatic tire obtained through the state of FIG. It is a top view which shows roughly the reinforcing layer of the carcass ply and bead part which were assembled on the shaping | molding drum in order to obtain the pneumatic tire which has a structure different from this invention. It is sectional drawing which shows roughly the arrangement | positioning state of the reinforcement layer in the pneumatic tire obtained through the state of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4a, 4b Carcass ply 5 Bead core 6 Bead filler 7 Breaker 8 Reinforcement layer C1 Reinforcement cord of carcass ply C2 Reinforcement cord of reinforcement layer

Claims (4)

  The outermost carcass is a pneumatic tire in which at least one layer of carcass ply whose reinforcing cord has an inclination angle with respect to the tire radial direction is mounted between a pair of bead parts, and a bead core and a bead filler are embedded in each bead part. A reinforcement layer extending between the ply and the bead filler to a position outside the tire radial direction from the apex of the bead filler and having a reinforcement cord having an inclination angle with respect to the tire radial direction is disposed to reinforce the reinforcement layer A pneumatic tire in which a cord is inclined in the same direction as the reinforcing cord of the outermost carcass ply.   The pneumatic tire according to claim 1, wherein an inclination angle of the reinforcing cord of the at least one layer of the carcass ply with respect to a tire circumferential direction is set to 30 ° to 85 °.   The pneumatic tire according to claim 1 or 2, wherein an inclination angle of the reinforcing cord of the reinforcing layer with respect to a tire circumferential direction is set to 30 ° to 90 °. The pneumatic tire according to any one of claims 1 to 3, wherein a crossing angle on a narrow angle side between the reinforcing cord of the outermost carcass ply and the reinforcing cord of the reinforcing layer is 60 ° or less.

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