JP2016088323A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire which is improved in durability of a bead part while suppressing a carcass ply from being damaged at the time of rim assembly.SOLUTION: A pneumatic tire comprises: a bead core 1a embedded in a bead part 1; a rubber filler 1b arranged outside in a tire radial direction of the bead core 1a; a carcass ply 4 wound up outward from inside around the bead core 1a; and a chafer 7 wound up outward from inside around the bead core 1a and arranged to wrap the carcass ply 4. The chafer 7 includes a 0 degree cord 7a having an inclination angle in a range of 0±15° relative to the carcass cord 4a included in the carcass ply 4 and a 90 degree cord having an inclination angle in a range of 90±15° relative to the carcass cord 4a.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire including a carcass ply wound around a bead core from the inside to the outside and a chafer arranged so as to wrap around the bead core from the inside to the outside and wrap the carcass ply.

  The bead portion of a pneumatic tire is often damaged by the carcass ply when the rim is assembled, and there is a case where a chafer is arranged to prevent the damage. In addition, the chafer may be arranged for the purpose of reinforcing the bead portion to increase the rigidity and improving the steering stability as in Patent Documents 1 to 3 below.

  The chafer is arranged so as to wrap the carcass ply rolled up around the bead core. A typical chafer has two types of cords inclined in opposite directions at an angle of about 45 ° with respect to the carcass cord of the carcass ply. Therefore, since the carcass ply and the chafer cord intersect at an angle of about 45 ° at the winding end of the chafer, the shear strain tends to increase, and there is a concern that the chafer will rise from the winding end and cause a failure such as separation. It was.

JP 2010-76560 A Japanese Patent No. 4276470 Japanese Patent No. 3449991

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a pneumatic tire in which the durability of the bead portion is improved while suppressing damage to the carcass ply when the rim is assembled.

The above object can be achieved by the present invention as described below.
That is, the pneumatic tire of the present invention, a bead core embedded in a bead portion, a rubber filler disposed on the outer side in the tire radial direction of the bead core, a carcass ply wound up from the inside around the bead core, In a pneumatic tire comprising a chafer wound around the bead core from the inside to the outside and arranged to wrap the carcass ply,
The chafer has a 0 degree cord having an inclination angle of 0 ± 15 ° with respect to a carcass cord included in the carcass ply and a 90 degree having an inclination angle of 90 ± 15 ° with respect to the carcass cord. Code.

  The pneumatic tire of the present invention includes a chafer arranged so as to wrap around the bead core from the inside to the outside and wrap the carcass ply, and can prevent damage to the carcass ply when assembling the rim. The chafer also includes a 0 degree cord having an inclination angle in the range of 0 ± 15 ° with respect to the carcass cord and a 90 degree cord having an inclination angle in the range of 90 ± 15 ° with respect to the carcass cord. . Since the 0 degree cord of the chafer is arranged substantially parallel to the carcass cord, the shear strain at the winding end of the chafer can be reduced. Furthermore, since the 90-degree cord of the chafer is arranged in a direction substantially orthogonal to the carcass cord, it is possible to suppress the end of the 0-degree cord from being lifted. As a result, it is possible to prevent separation of the chafer's rolled-up end portion and prevent separation, thereby improving the durability of the bead portion.

  In the pneumatic tire of the present invention, it is preferable that the 90-degree cord has a discontinuous portion that is divided on the tire circumference.

  Since the 90-degree cord extends along the tire circumferential direction, the chafer is difficult to extend in the tire circumferential direction, and it is difficult to wind up the chafer during tire molding. Since the 90-degree cord has a discontinuous portion, tire molding becomes easy.

  In the pneumatic tire of the present invention, it is preferable that the 0 degree cord is thinner than the 90 degree cord.

  By narrowing the 0 degree cord, it is possible to suppress the lifting of the end portion of the 0 degree cord, so that the separation at the winding end portion of the chafer can be delayed. On the other hand, by thickening the 90 degree code, it is possible to effectively suppress the end of the 0 degree code from being lifted.

Tire meridian cross-sectional view showing an example of the pneumatic tire of the present invention Front view of the bead viewed from the front of the tire The front view which looked at the bead part concerning other embodiments from the tire front. Front view for explaining the structure of the chafer Front view for explaining the structure of a chafer according to another embodiment Front view for explaining the structure of a chafer according to another embodiment

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. A tire T shown in FIG. 1 is an example of a pneumatic tire according to the present invention, and shows a tire meridian cross section when a specified rim is mounted. When the specified rim is mounted, the tire is mounted on the rim specified by JATMA corresponding to the tire size, and the maximum air pressure corresponding to the single wheel maximum load capacity specified by JATMA is applied.

  The tire T includes a pair of bead portions 1, a sidewall portion 2 that extends outward from the bead portion 1 in the tire radial direction, and a tread portion 3 that forms a tread surface that is connected to an outer end in the tire radial direction of the sidewall portion 2. Prepare. An annular bead core 1a made of a converging body in which rubber-coated bead wires are laminated and wound is embedded in the bead portion 1, and a rubber filler 1b is disposed on the outer side in the tire radial direction of the bead core 1a.

  The carcass ply 4 extends between the bead cores 1 a disposed in the pair of bead portions 1, and is wound up from the inside to the outside around the bead core 1 a. In the present embodiment, two carcass plies 4 are provided. On the outer side in the tire width direction of the bead core 1a and the rubber filler 1b, a winding portion of the carcass ply 4 is disposed, and the tip thereof becomes a winding end. The carcass ply 4 is formed by covering a carcass cord arranged in a direction substantially orthogonal to the tire circumferential direction with a topping rubber. As the carcass cord, an organic fiber cord such as polyester, rayon, nylon, aramid, or a steel cord is preferably used.

  An inner liner rubber 5 constituting the inner peripheral surface of the tire T is provided inside the carcass ply 4. The inner liner rubber 5 has a function of blocking the permeation of the gas filled in the tire. In the sidewall portion 2, a sidewall rubber 6 constituting the outer wall surface of the tire T is provided outside the carcass ply 4.

  The chafer 7 is arranged so as to wrap around the carcass ply 4 by being wound up from the inside to the outside around the bead core 1a. The chafer 7 includes a bottom portion 71 that protects the inner surface in the tire radial direction of the bead portion 1, and an inner winding portion 72 and an outer winding portion 73 that are respectively connected to both ends of the bottom portion 71 in the tire width direction. The bottom portion 71 is exposed on the tire surface so that the inner surface in the tire radial direction of the bead portion 1 can be appropriately protected. The inner winding portion 72 and the outer winding portion 73 are not exposed on the tire surface in the present embodiment, but may be exposed on the tire surface.

  The distal end portion 72E of the inner winding portion 72 and the distal end portion 73E of the outer winding portion 73 are 5 to 20 mm higher on the outer side in the tire radial direction than the upper surface of the bead core 1a (the outer surface in the tire radial direction of the bead core 1a). Thereby, damage around bead core 1a can be prevented appropriately.

  FIG. 2 is a front view of the bead portion 1 as viewed from the front of the tire, and schematically shows the cords included in the carcass ply 4 and the chafer 7. The chafer 7 includes a 0 degree cord 7a having an inclination angle α in the range of 0 ± 15 ° with respect to the carcass cord 4a and a 90 degree cord 7b having an inclination angle β in the range of 90 ± 15 ° with respect to the carcass cord 4a. Including. The 0 degree cord 7a is arranged substantially parallel to the extending direction of the carcass cord 4a, and preferably arranged parallel to the extending direction of the carcass cord 4a. The 90-degree cord 7b is arranged so as to be substantially orthogonal to the extending direction of the carcass cord 4a, and preferably arranged so as to be orthogonal to the extending direction of the carcass cord 4a. In another embodiment shown in FIG. 3, the 0 degree cord 7a has an inclination angle of 0 ° with respect to the carcass cord 4a (arranged parallel to the carcass cord 4a), and the 90 degree cord 7b has the carcass cord 4a. It has an inclination angle of 90 ° with respect to the cord 4a (arranged so as to be orthogonal to the carcass cord 4a).

  The 0 degree cord 7a and the 90 degree cord 7b may be layered as shown in FIG. 4, or may be knitted into a net shape as shown in FIG. In the example of FIG. 4, the 0 degree code 7a is arranged outside the carcass cord 4a, and the 90 degree code 7b is arranged further outside the 0 degree code 7a. However, the 90 degree cord 7b may be disposed outside the carcass cord 4a, and the 0 degree cord 7a may be disposed further outside the 90 degree cord 7b.

  Although not shown in FIG. 4, the actual chafer 7 includes a sheet-like member in which the 0-degree cord 7a aligned in parallel is covered with a topping rubber, and a 90-degree cord 7b aligned in parallel with a topping rubber. The coated sheet-like member is laminated. Further, in the chafer 7 of FIG. 5, the 0 degree cord 7a and the 90 degree cord 7b knitted in a net shape are covered with a topping rubber.

  As the 0-degree cord 7a and 90-degree cord 7b of the chafer 7, organic fiber cords such as polyester, rayon, nylon, polyethylene naphthalate (PEN), polyethylene terephthalate (PET), and aramid are preferably used. The 0 degree code 7a and the 90 degree code 7b may have the same thickness, but as shown in FIGS. 4 and 5, the 0 degree code 7a is preferably thinner than the 90 degree code 7b. For example, the wire diameter of the 0 degree cord 7a is preferably 0.20 to 0.50 mm, and the wire diameter of the 90 degree cord 7b is preferably 0.30 to 0.60 mm.

  The pitch P1 between the 0 degree cords 7a is preferably 0.7 to 1.0 mm. The pitch P2 between the 90-degree cords 7b is preferably 0.6 to 0.9 mm. The pitch P3 between the carcass cords 4a is wider than the pitch P1 between the 0 degree cords 7a and the pitch P2 between the 90 degree cords 7b, for example, 0.8 to 1.1 mm. The pitch between cords is defined by the distance between the centers of adjacent cords.

  Moreover, it is preferable that the 90 degree | times code | cord | chord 7b has a discontinuous part divided | segmented on the tire periphery. FIG. 6 is a diagram schematically showing the chafer 7 viewed from the front of the tire. In this example, the 90-degree cord 7b has four discontinuous portions 74 on the tire circumference. It is preferable to provide four or more discontinuous portions 74.

  The pneumatic tire of the present invention is the same as a normal pneumatic tire except that the chafer cord is configured as described above, and any conventionally known material, shape, structure, manufacturing method, etc. are adopted in the present invention. be able to.

  Hereinafter, in order to specifically show the configuration and effects of the present invention, a durability test of the bead portion was performed, which will be described below. The size of the tire used for the test was LT265 / 70R17 121, and was mounted on a rim having a size specified by JATMA.

  In accordance with the conditions set forth in the US automobile safety standard FMVSS 139, a durability test was performed with a drum type testing machine, and the travel distance until a failure occurred in the bead portion was measured. It shows by the index when the result of Comparative Example 1 is set to 100, and it shows that it is excellent in durability, so that a numerical value is large.

Comparative Example 1
A case in which the chafer includes two types of cords inclined in opposite directions at an angle of 45 ° with respect to the carcass cord is referred to as Comparative Example 1. The two types of cords were knitted in a net shape.

Examples 1 and 2
An embodiment in which the chafer includes a 0 degree cord having an inclination angle in the range of 0 ± 15 ° with respect to the carcass cord and a 90 degree cord having an inclination angle in the range of 90 ± 15 ° with respect to the carcass cord. 1 and 2. In Example 1, the 0 degree code and the 90 degree code were knitted into a net shape as shown in FIG. 5, and in Example 2, the 0 degree code and the 90 degree code were laminated in layers as shown in FIG.

  As a result of the durability test, assuming that the result of Comparative Example 1 is 100, Example 1 is 150 and Example 2 is 150. That is, the pneumatic tires of Examples 1 and 2 are superior in durability of the bead portion as compared with Comparative Example 1. In the first embodiment, since the 0 degree cord and the 90 degree cord are knitted in a net shape, it is easier to manufacture a chafer than in the second embodiment.

1 Bead section
1a Bead core
1b Rubber filler
4 Carcass ply
4a Carcass cord
7 Chefa
7a 0 degree code
7b 90 degree code

Claims (3)

A bead core embedded in the bead portion, a rubber filler disposed on the outer side in the tire radial direction of the bead core, a carcass ply wound around from the inside to the outside around the bead core, and wound up from inside to outside around the bead core A pneumatic tire provided with a chafer disposed to wrap the carcass ply,
The chafer has a 0 degree cord having an inclination angle of 0 ± 15 ° with respect to a carcass cord included in the carcass ply and a 90 degree having an inclination angle of 90 ± 15 ° with respect to the carcass cord. A pneumatic tire characterized by including a cord.   The pneumatic tire according to claim 1, wherein the 90-degree cord has a discontinuous portion divided on a tire circumference. The pneumatic tire according to claim 1 or 2, wherein the 0 degree code is narrower than the 90 degree code.

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