JP2018100044A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire improved in durability of a bead part.SOLUTION: A pneumatic tire 10 comprises plural carcass plies 20A and 20B including: body parts 21A and 21B disposed between a pair of bead parts 11; and wind-up parts 22A and 22B that extend from the body parts 21A and 21B, and that are folded back around a bead core 12 from a tire width direction inner side Y1 to an outer side Y2 in order to be wound up to a tire radial direction outer side Z2 along a bead filler 13. In the pneumatic tire, ply cords 23A and 23B disposed on the carcass plies 20A and 20B comprise portions 23A2 and 23B2 that are positioned on the tire width direction outer side Y2 of the bead filler 13 and arranged in a waveform. In the plural carcass plies 20A and 20B, the portions 23A2 and 23B2 arranged in the waveform are superposed so as to mutually intersect in a tire side view.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire.

  In a pneumatic radial tire, the following Patent Document 1 proposes that a cord reinforcing layer including a cord such as a nylon cord or a steel cord is provided along a winding portion of a carcass ply in order to improve the durability of a bead portion. Yes.

  Thus, by providing and reinforcing the cord reinforcing layer around the carcass ply winding portion, it is possible to disperse the distortion of the carcass ply winding end, but the rigidity of the cord reinforcing layer is arranged around the bead portion. Since it is extremely higher than rubber, stress strain is concentrated at the end of the cord reinforcing layer, and the durability of the bead portion tends to be lowered.

  Patent Document 2 below proposes to provide a ply cord disposed in an end region of the winding part in a wave shape in order to suppress separation of the winding part of the carcass ply. In Patent Document 2, as a result of the carcass cord included in the end region of the winding part following the surrounding deformation without directly burdening the tension due to the expansion and contraction of the wave shape, It is disclosed that stress concentration is relaxed and separation can be suppressed. However, Patent Document 2 does not suggest that the ply cords provided in a wave shape are arranged so as to cross each other to achieve high rigidity.

JP 2016-43815 A JP 2009-269426 A

  This invention is made | formed in view of the above point, and it aims at providing the pneumatic tire which can improve the durability of a bead part.

  A pneumatic tire according to an embodiment includes a pair of bead portions each having a bead core and a bead filler disposed on a tire radial direction outer side of the bead core, a main body portion provided between the pair of bead portions, and the main body. In a pneumatic tire provided with a plurality of carcass plies having a winding portion extending from a portion and turned around from the inside in the tire width direction around the bead core to the outside in the tire radial direction along the bead filler, The carcass ply includes a ply cord disposed in a direction orthogonal to a tire circumferential direction and a covering rubber that covers the ply cord, and the ply cord is a portion located on the outer side in the tire width direction of the bead filler. Are provided in a wave shape, and a plurality of front portions are arranged so that the portions provided in the wave shape intersect each other in a tire side view. Carcass plies are superimposed.

  In a preferred aspect of the present invention, the plurality of carcass plies may be overlapped by shifting the phase of the portion provided in the wave shape.

  In another preferable aspect of the present invention, the wave shape provided in the plurality of carcass plies may have a longer wavelength toward the outer side in the tire radial direction.

  In another preferable aspect of the present invention, the wave shape provided in the plurality of carcass plies may have a smaller amplitude toward the outer side in the tire radial direction.

  In the pneumatic tire of the embodiment, since the plurality of carcass plies are overlapped so that the ply cords provided in a wave shape intersect each other on the outer side in the tire width direction of the bead filler, the durability of the bead portion is improved. be able to.

The tire meridian half section view showing the pneumatic tire of this embodiment. The figure which looked at the bead core, bead filler, and carcass ply of the pneumatic tire of Drawing 1 from the tire side. It is the figure which looked at the ply cord provided in the winding part of the carcass ply of the pneumatic tire concerning the example of a change from the tire side. It is the figure which looked at the ply cord provided in the winding part of the carcass ply of the pneumatic tire concerning other modifications from the tire side.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a tire meridian cross-sectional view showing an example of a pneumatic tire (hereinafter referred to as “tire”) 10 of the first embodiment, and shows a half cross-section in a state where the rim flange 1 of a specified rim is mounted. .

  In the present specification, the tire width direction is a direction parallel to the tire rotation axis and is synonymous with the tire axis direction. Show. In addition, the tire radial direction (radial direction) is a direction perpendicular to the tire rotation axis, and is indicated by a symbol Z in the figure, and the inner side and the outer side in the tire radial direction are indicated by symbols Z1 and Z2, respectively. Moreover, it is the direction on the periphery centering on a tire rotating shaft, and it shows with the code | symbol R in a figure.

  The tire 10 of the present embodiment includes a pair of left and right bead portions 11 provided on both sides of the tire width direction Y, a pair of sidewall portions 14 extending outward from the bead portion 11 in the tire radial direction, and left and right sidewall portions 14. And a tread portion 16 provided between the sidewall portions 14 so as to connect the radially outer ends.

  The bead portion 11 includes an annular bead core 12 made of a converging body obtained by laminating and winding rubber-coated bead wires, and a rubber bead filler 13 disposed on the outer side Z2 of the bead core 12 in the tire radial direction. The bead filler 13 is made of hard rubber and has a triangular cross-section with a narrower width toward the tip end extending from the tire maximum width position to the outer side Z2 in the tire radial direction.

  Inside the tire 10, two toroidal carcass plies 20 </ b> A and 20 </ b> B are provided between a pair of bead portions 11. The two carcass plies 20A and 20B are composed of two sheets, a first carcass ply 20A on the tire inner surface side and a second carcass ply 20B provided on the outer side. The two carcass plies 20 </ b> A and 20 </ b> B reach the bead portion 11 from the tread portion 16 through the side wall portions 14 on both sides, and are wound and locked around the bead core 12 in the bead portion 11. In this example, a case where two carcass plies 20 </ b> A and 20 </ b> B are provided will be described, but three or more carcass plies may be provided inside the tire 10.

  A belt 30 is provided on the tire outer surface side of the second carcass ply 20B in the tread portion 16. The belt 30 is formed by covering a plurality of cords (for example, steel cords) with rubber, and reinforces the tread portion 16 on the outer periphery of the two carcass plies 20A and 20B. A tread rubber 32 whose outer surface is a ground contact surface is provided on the outer side in the tire radial direction from the belt 30.

  An inner liner 34 serving as an air-resistant rubber layer that constitutes the inner peripheral surface of the tire 10 is provided on the tire inner surface side of the first carcass ply 20A. Sidewall rubber 33 constituting the outer wall surface of the tire 10 is provided on the sidewall portion 14 on both sides in the tire width direction of the first carcass ply 20A.

  A rim strip 40 is provided on the outer side Y2 of the bead portion 11 in the tire width direction. The upper part of the rim strip 40 is in contact with the lower part of the sidewall rubber 33. The lower part of the rim strip 40 enters the tire radial inner side Z1 from the bead core 12 and is in contact with the inner liner 34. The rim strip 40 constitutes the outer surface of the tire around the bead portion 11 and contacts the rim flange 1 when the tire 10 is assembled with the rim.

  A rim line 35 is provided as a small protrusion at a predetermined position on the tire surface. The rim line 35 is a line for confirming that the tire 10 and the regular rim are concentric when the tire 10 is mounted on the regular rim. For that purpose, the rim line 35 is provided over the circumference in the tire circumferential direction, and is a circle centered on the rotation axis of the tire 10. The predetermined position where the rim line 35 is provided is a position where the rim line 35 protrudes outward in the tire radial direction by a certain distance from the outer periphery of the flange of the regular rim. Usually, the rim line 35 is provided at the boundary between the rim strip 40 and the sidewall rubber 33 on the tire surface.

  In the tire 10 having such a configuration, the two carcass plies 20A and 20B extend from the main body portions 21A and 21B that are provided between the pair of bead portions 11 and form a skeleton of the tire, and the main body portions 21A and 21B. Winding portions 22 </ b> A and 22 </ b> B are folded around the bead portion 11 from the inner side to the outer side in the tire width direction so as to wrap the bead core 12 and the bead filler 13.

  The winding portions 22A and 22B of the carcass plies 20A and 20B extend to the tire radial direction outer side Z2 along the tire width direction outer side surfaces of the bead core 12 and the bead filler 13. The leading ends (that is, the winding ends 22AE and 22BE) of the winding portions 22A and 22B end in the sidewall portion 14 beyond the upper end (that is, the outer end in the tire radial direction) 13A of the bead filler 13.

  The winding part 22B of the second carcass ply 20B is in contact with the main body part 21B at the outer side Z2 of the bead filler 13 in the tire radial direction. The winding portion 22A of the first carcass ply 20A covers the outside of the winding portion 22B of the second carcass ply 20B and is formed at a higher winding position than the winding portion 22B of the second carcass ply 20B (that is, outward in the tire radial direction). Has been. The winding portion 22B of the first carcass ply 20A is in contact with the main body portion 21B of the second carcass ply 20B.

  As shown in FIG. 2, the two carcass plies 20A and 20B include a plurality of ply cords 23A and 23B provided at intervals in the tire circumferential direction R, and a covering rubber that covers the plurality of ply cords 23A and 23B. 24A, 24B. As the ply cords 23A and 23B, a metal cord such as a steel cord or an organic fiber cord such as polyester or nylon is used.

  Specifically, portions of the ply cords 23A and 23B provided in the main body portions 21A and 21B of the carcass plies 20A and 20B (hereinafter, these portions may be referred to as “cord main body portions”) 23A1 and 23B1 It is arranged at intervals in the direction R and extends along a direction substantially orthogonal to the tire circumferential direction R.

  Of the ply cords 23A and 23B, portions provided on the winding portions 22A and 22B of the carcass plies 20A and 20B (hereinafter, these portions are also referred to as “cord winding portions”) 23A2 and 23B2 have an amplitude in the tire circumferential direction R. And has a wave shape extending in the tire radial direction while meandering. The cord winding portion 23A2 of the first carcass ply 20A and the cord winding portion 23B2 of the second carcass ply 20B are arranged in a mesh shape so as to intersect with each other in the tire side view as shown in FIG.

  As a method of crossing the cord winding portion 23A2 of the first carcass ply 20A and the cord winding portion 23B2 of the second carcass ply 20B, as shown in FIG. 2, the cord winding portion 23A2 and the cord winding portion 23B2 have a wave-like phase. In addition to shifting the first carcass ply 20A and the second carcass ply 20B by shifting the position (that is, the position in the tire radial direction Z), for example, the cord winding portion 23A2 and the cord winding portion 23B2 have wave-shaped wavelengths and amplitudes. The cord winding part 23A2 and the cord winding part 23B2 can be crossed also by making different.

  The ply cords 23A and 23B provided on the two carcass plies 20A and 20B are arranged, for example, at intervals of 0.2 to 1.2 mm in the tire circumferential direction R, and the wave shapes of the cord winding portions 23A2 and 23B2 Preferably has a wave shape with an amplitude of 0.5 mm or more and a wavelength in the range of 4.0 mm to 20 mm. In addition, when the cord winding portions 23A2 and 23B2 cross each other by shifting the waveform phase between the cord winding portion 23A2 and the cord winding portion 23B2, it is preferable that the phase difference of the waveform is in the range of 140 ° to 220 °. .

  In this specification, the interval between the ply cords 23A and 23B and the amplitude, wavelength, and phase difference of the wave shapes of the cord winding portions 23A2 and 23B2 are measured in a free state before the pneumatic tire is assembled to the rim. Value.

  In the tire 10 of the present embodiment, the cord winding portion 23A2 and the cord winding portion 23B2 located on the outer side in the tire width direction of the bead filler 13 are each provided in a wave shape, and the first carcass ply so as to intersect with each other in the tire side view. 20A and the second carcass ply 20B are overlapped. For this reason, the ply cords 23A and 23B form a network structure on the outer side Y2 of the bead filler 13 in which large strains are likely to concentrate when the tire is deformed, so that the carcass plies 20A and 20B can be made highly rigid. The durability around the bead portion 11 can be improved.

  Moreover, in this embodiment, even if the ply cords 23A and 23B are so-called radial tires arranged in a direction substantially perpendicular to the tire circumferential direction R, the ply cords 23A and 23B form a mesh structure, so Deformation in the circumferential direction R can be suppressed.

  In the present embodiment, the winding portion 22B of the second carcass ply 20B is in contact with the main body portion 21B at the outer side Z2 of the bead filler 13 in the tire radial direction. Since the cord main body portion 23B1 provided in the main body portion 21B and the corrugated cord winding portion 23B2 provided in the winding portion 22B intersect each other in a tire side view, the contact portion between the winding portion 22B and the main body portion 21B Stiffness can be increased.

  In the present embodiment, since the winding portion 22A of the first carcass ply 20A is in contact with the main body portion 21B, the cord main body portion 23B1 provided in the main body portion 21B and the corrugated shape provided in the winding portion 22A. The cord winding portions 23A2 cross each other in a tire side view, and the rigidity of the contact portion between the winding portion 22B and the main body portion 21B can be increased.

(Modification 1)
In the above embodiment, the case where the wave shapes provided in the cord winding portions 23A2 and 23B2 of the carcass plies 20A and 20B do not change in the tire radial direction Z and repeats the same shape has been described, but at least one of the cord winding portions 23A2 and 23B2 May be changed in the tire radial direction Z.

  Specifically, the wave shapes provided in the cord winding portions 23A2 and 23B2 of the carcass plies 20A and 20B may change so that the wavelength becomes longer toward the outer side Z2 in the tire radial direction as illustrated in FIG. As shown in FIG. 4, the amplitude may change so that the amplitude decreases toward the outer side Z2 in the tire radial direction, and the amplitude decreases as the wavelength increases toward the outer side Z2 in the tire radial direction. May be.

  Thus, by changing the waveform provided in the cord winding portions 23A2 and 23B2, the locations where the cord winding portions 23A2 and 23B2 intersect with each other can be gradually decreased toward the outer side Z2 in the tire radial direction. As a result, the rigidity of the hoisting portions 22A and 22B gradually decreases toward the outer side Z2 in the tire radial direction, so that distortion generated during tire deformation can be dispersed and durability around the bead portion 11 is improved. be able to.

(Modification 2)
In the above-described embodiment, almost the entire cord winding portion 23A2 of the first carcass ply 20A and the cord winding portion 23B2 of the second carcass ply 20B are provided in a wave shape, but at least the tire of the bead filler 13 of the ply cords 23A and 23B. It is only necessary that the portions located on the outer side Y2 in the width direction are provided in a wave shape and intersect each other.

  The ply cords 23A and 23B may be provided in a wave shape over the entire bead filler 13, but the ply cords 23A and 23B may be provided in a wave shape in a region overlapping with a part of the bead filler 13 and the tire radial direction Z. Good. When a wave shape is provided on a part of the tire width direction outer side Y2 of the bead filler 13, the ply cords 23A and 23B are provided in a wave shape in a region from the outer side Z2 in the tire radial direction of the rim line 35 to the bead core 12 beyond the rim line 35. It is preferable.

  As mentioned above, although embodiment of this invention was described, this embodiment is shown as an example and is not intending limiting the range of invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention.

In order to specifically show the configuration and effects of the above-described embodiment, tires of comparative examples and examples 1 and 2 (tire size: 195 / 85R16 114L) were prototyped and performance evaluation was performed. The evaluation method is as follows.
-Bead durability The test was run on a drum with a diameter of 1700 mm until the test tire failed while gradually increasing the load from the initial conditions of an air pressure of 600 KPa, a reference load of 11.6 KN, and a speed of 65 Km / h. The travel distance of the comparative example is shown as an index with 100 as the travel distance. The larger the value, the better.

  The tires of the comparative example and Examples 1 and 2 for which the performance evaluation was performed have the same structure as the tire 10 of FIG. 1 except for the shape of the ply cord provided in the winding portion of the two carcass plies.

  Specifically, the comparative example is a tire in which a ply cord provided in a winding portion of two carcass plies extends linearly along the tire radial direction.

  Example 1 is a tire in which the ply cords provided in the winding portions of the two carcass plies have a wave shape and intersect each other in the tire side view, and the wave shape does not change in the tire radial direction It is.

  Example 2 is a tire in which the ply cords provided at the winding portions of the two carcass plies have a wave shape and intersect each other in the side view of the tire. The tire has a longer wavelength and a smaller waveform amplitude.

  In each prototype tire, the distance in the tire circumferential direction R between the ply cords provided on the two carcass plies, the wavelength and amplitude of the wave shape formed in the cord winding portion, the first carcass ply and the second carcass ply Table 1 shows the phase difference of the wave shape formed in the cord winding portion.

結果は表１に示す通りである。実施例１〜２では、比較例に比べてビード耐久性が向上した。コード巻き上げ部に形成された波形状の波長及び振幅をタイヤ径方向で変化させた実施例２ではビード耐久性がより一層向上した。

The results are as shown in Table 1. In Examples 1-2, bead durability improved compared with the comparative example. In Example 2 in which the wavelength and amplitude of the wave shape formed in the cord winding portion were changed in the tire radial direction, the bead durability was further improved.

DESCRIPTION OF SYMBOLS 10 ... Tire, 11 ... Bead part, 12 ... Bead core, 13 ... Bead filler, 14 ... Side wall part, 16 ... Tread part, 20 ... Carcass ply, 20A ... 1st carcass ply, 20B ... 2nd carcass ply, 21A ... Body part, 21B ... Body part, 22A ... Rolling part, 22B ... Rolling part, 22AE ... Rolling edge, 22BE ... Rolling edge, 23A ... Ply cord, 23B ... Ply cord, 23A1 ... Cord body part, 23B1 ... Cord body part, 23A2: Cord winding portion, 23B2: Cord winding portion, 24A ... Cover rubber, 24B ... Cover rubber, 33 ... Side wall rubber, 34 ... Inner liner, 35 ... Rim line, 40 ... Rim strip

Claims (4)

A pair of bead portions having a bead core and a bead filler disposed on the outer side in the tire radial direction of the bead core;
A main body provided between a pair of the bead parts, and a winding that extends from the main body part, wraps around the bead core from the inner side to the outer side in the tire width direction, and winds up outward in the tire radial direction along the bead filler. In a pneumatic tire provided with a plurality of carcass plies having a portion,
The carcass ply includes a ply cord disposed in a direction orthogonal to a tire circumferential direction, and a covering rubber that covers the ply cord,
The ply cord has a wave-shaped portion positioned on the outer side in the tire width direction of the bead filler, and the plurality of carcass plies are overlapped so that the portions provided in the wave shape intersect with each other in a side view. Pneumatic tire.   The pneumatic tire according to claim 1, wherein the plurality of carcass plies are overlapped with each other while shifting the phase of the portion provided in the wave shape.   The pneumatic tire according to claim 1 or 2, wherein the wave shape provided in the plurality of carcass plies has a longer wavelength toward the outer side in the tire radial direction.   The pneumatic tire according to any one of claims 1 to 3, wherein the wave shape provided in the plurality of carcass plies has a smaller amplitude toward the outer side in the tire radial direction.

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