JP2015123942A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress increase of tire weight, and improve durability of a bead part.SOLUTION: A pneumatic radial tire comprises: a metal reinforcement layer 32 wound from a tire axial direction inside Y1 to an outside Y2 on the outside of a carcass ply 18; a first fiber reinforcement layer 34 wound from the tire axial direction inside Y1 to the outside Y2 on the outside of the metal reinforcement layer 32; and a second fiber reinforcement layer 36 disposed closer to the tire axial direction outside Y2 than at least a bead core 26. An angle θ1 of a metal cord 33 included in the metal reinforcement layer 32 to a ply cord 19 is larger than angles θ2, θ3 of organic fiber cords 35, 37 included in the first fiber reinforcement layer 34 and the second fiber reinforcement layer 36 to the ply cord 19, and an inclination direction G1 of the organic fiber cord 35 of the first fiber reinforcement layer 34 to the ply cord 19 is inclined opposite to an inclination direction G2 of the organic fiber cord 37 of the second fiber reinforcement layer 36 and the metal cord 33 of the metal reinforcement layer 32.

Description

  The present invention relates to a pneumatic radial tire.

  In a pneumatic radial tire, particularly a heavy-duty pneumatic radial tire, it is required to improve the durability of the bead portion. In order to improve the durability of the bead part, it is effective to reduce the distortion at the winding end of the carcass ply by suppressing the deformation of the bead part. Therefore, providing the reinforcement layer called a chafer along the winding part of a carcass ply is performed (refer patent documents 1-3).

  Patent Documents 1 and 2 disclose that, as such a reinforcing layer, a steel cord reinforcing layer including a steel cord and a two-layer fiber cord reinforcing layer including an organic fiber are provided in the winding portion of the carcass ply. .

JP-A-6-286411 JP 2002-219913 A

  As described above, by providing and reinforcing a metal reinforcing layer including a steel cord and a fiber reinforcing layer including an organic fiber cord around the winding portion of the carcass ply, the distortion at the winding end of the carcass ply can be dispersed. The durability of the bead portion can be improved.

  However, when a plurality of reinforcing layers are provided in this way, the ends of the plurality of reinforcing layers are likely to be close to each other on the inner side in the tire axial direction of the bead core. Durability tends to decrease. In contrast, it is conceivable to increase the thickness of each member such as a reinforcing layer to improve rigidity, but in such a case, the thickness of the bead portion increases and the tire mass increases, resulting in an increase in cost and rolling. There is a problem that leads to deterioration of resistance.

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

  A pneumatic radial tire according to the present invention includes a bead core embedded in a bead portion, a bead filler disposed on the outer side in the tire radial direction of the bead core, and a ply wound around the bead core from the inner side in the tire axial direction to the outer side. A carcass ply including a cord, a metal reinforcing layer including a metal cord wound outward from the inner side in the tire axial direction outside the carcass ply, and an organic wound outward from the inner side in the tire axial direction outside the metal reinforcing layer An angle of the metal cord included in the metal reinforcement layer with respect to the ply cord, the first fiber reinforcement layer including a fiber cord, and a second fiber reinforcement layer including an organic fiber cord provided at least on the outer side in the tire axial direction from the bead core. Is an organic fiber cord provided in the first fiber reinforcement layer and the second fiber reinforcement layer. The inclination direction of the organic fiber cord of the first fiber reinforcement layer with respect to the ply cord is greater than the angle with respect to the ply cord, and the inclination direction of the organic fiber cord of the metal reinforcement layer and the second fiber reinforcement layer Inclined in the opposite direction.

  As a preferable aspect of the pneumatic radial tire according to the present invention, the tire radial outer side end of the metal reinforcing layer on the inner side in the tire axial direction of the bead core is a tire from the normal of the tire inner side surface passing through the winding end of the carcass ply. An outer end in the tire radial direction of the first fiber reinforcement layer located on the outer side in the tire axial direction of the bead core is located on the outer side in the tire radial direction from the outer end in the tire radial direction of the metal reinforcement layer. . In addition, a tire includes a reinforcing rubber layer provided between the metal reinforcing layer and the carcass ply on the inner side in the tire axial direction of the bead core, and an outer end in the tire radial direction of the reinforcing rubber layer is the first fiber reinforcing layer. It is located on the outside in the tire radial direction from the outer end in the tire radial direction. Further, the second fiber reinforcement layer is wound up from the inner side in the tire axial direction on the outer side of the metal reinforcing layer, and the outer end in the tire radial direction of the second fiber reinforcement layer on the inner side in the tire axial direction of the bead core, It is located inward in the tire radial direction from the outer end in the tire radial direction of the metal reinforcing layer. Further, the first fiber reinforcement layer is formed of an organic fiber cord in an extension portion where the angle of the organic fiber cord in the folded portion located around the bead core with respect to the ply cord is positioned on the outer side in the tire radial direction from the folded portion. It is larger than the angle with respect to the ply cord. In addition, on the outer side in the tire axial direction of the bead core, the winding end of the carcass ply is positioned outward in the tire radial direction from the outer end in the tire radial direction of the metal reinforcing layer.

  ADVANTAGE OF THE INVENTION According to this invention, durability of a bead part can be improved, suppressing the increase in tire mass.

1 is a half sectional view of a pneumatic radial tire according to a first embodiment. It is sectional drawing of the bead part of the pneumatic radial tire which concerns on 1st Embodiment. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an inclination angle and an inclination direction of a cord included in each reinforcing layer with respect to a ply cord in a pneumatic radial tire according to a first embodiment, wherein (a) is a metal cord, (b) is a first organic fiber cord, ( c) shows the second organic fiber cord. It is sectional drawing of the bead part of the pneumatic radial tire which concerns on 2nd Embodiment. It is a schematic diagram which shows the inclination | tilt angle and inclination | tilt direction of the code | cord | chord which each reinforcement layer has with respect to the ply cord in the pneumatic radial tire which concerns on 2nd Embodiment, (a) is a metal cord, (b) is a 1st organic fiber cord, ( c) shows the second organic fiber cord. It is sectional drawing of the bead part of the pneumatic radial tire which concerns on other embodiment.

(First embodiment)
FIG. 1 shows a pneumatic radial tire (hereinafter referred to as “tire”) 10 according to a first embodiment of the present invention, and shows a half section in a state where the pneumatic rim 1 is mounted on a specified rim 1.

  In the present specification, the tire axial direction is a direction parallel to the tire rotation axis and is synonymous with the tire width direction, and is indicated by a symbol Y in the drawing, and the inner side and the outer side in the tire axial direction are denoted by Y1 and Y2, respectively. 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.

  The tire 10 according to the embodiment connects a pair of left and right bead portions 12, a pair of sidewall portions 14 extending from the bead portion 12 to the outer side in the tire radial direction, and radially outer ends of the left and right sidewall portions 14. The tread part 16 provided between the side wall parts 14 is provided.

  A carcass ply 18 extending between the pair of bead portions 12 is embedded in the tire 10. The carcass ply 18 extends from the tread portion 16 through the sidewall portion 14, and both ends of the bead portion 12 are locked. A belt 20 is provided on the outer peripheral side of the carcass ply 18 in the tread portion 16, and the tread portion 16 is reinforced on the outer periphery of the carcass ply 18. The carcass ply 18 is formed by covering a ply cord 19 arranged in a direction substantially orthogonal to the tire circumferential direction with a topping rubber. As the ply cord 19, a steel cord or an organic fiber cord is used.

  Inside the carcass ply 18, an inner liner 22 is provided as an air permeable rubber layer that constitutes the inner peripheral surface of the tire 10. In the sidewall portion 14, a sidewall rubber 24 that constitutes the outer wall surface of the tire 10 is provided outside the carcass ply 18.

  As shown in an enlarged view in FIG. 2, the bead portion 12 includes an annular bead core 26 made of a converging body obtained by laminating and winding rubber-coated bead wires, and a rubber made of rubber disposed on the outer side Z <b> 2 in the tire radial direction of the bead core 26. The bead filler 28 is embedded.

  The carcass ply 18 is wound around the bead core 26 from the tire axial direction inner side Y1 to the outer side Y2. Specifically, the carcass ply 18 has a main body portion 18A extending from the side wall portion 14 disposed along the inner surface in the tire axial direction of the bead core 26 and the bead filler 28, and the inner side in the tire radial direction of the bead core 26 (see FIGS. 1 and 2). (Lower side) It winds up to the tire axial direction outer side Y2 through Z1. That is, the carcass ply 18 is folded back at the inner side Z1 in the tire radial direction of the bead core 26, and the outer side Y2 of the bead core 26 in the tire axial direction forms a winding portion 18B. The winding portion 18B of the carcass ply 18 is disposed along the tire axial direction outer side surface of the bead core 26 and the bead filler 28, and the tip thereof (that is, the outer end in the tire radial direction of the winding portion 18B) is the winding end 18E. It becomes.

  Around the carcass ply 18 in the bead portion 12, one metal reinforcing layer 32 including a metal cord 33 and two fiber reinforcing layers including organic fiber cords 35 and 37, specifically, a first fiber reinforcement A layer 34 and a second fiber reinforcement layer 36 are provided.

  The metal reinforcing layer 32 is a steel chafer formed by coating a metal cord 33 such as a steel cord with a topping rubber, and the outer side of the carcass ply 18 is wound up from the tire axial direction inner side Y1 to the outer side Y2. That is, the metal reinforcing layer 32 is provided on the outer surface so as to wrap the carcass ply 18 in the bead portion 12, and is provided adjacent to the main body portion 18 </ b> A of the carcass ply 18 on the tire shaft direction inner side Y <b> 1 of the bead core 26. 26 on the outer side Y2 in the tire axial direction adjacent to the winding portion 18B.

  The metal reinforcing layer 32 is a tire inner side surface (that is, an inner surface of the inner liner) in which a tire radial outer end 32Ein located on the tire axial inner side Y1 of the bead core 26 (or the bead filler 28) passes through the winding end 18E of the carcass ply 18. The tire radial direction outer end 32Eout located on the tire radial direction outer side Z2 from the normal line L of 10i and located on the tire axial direction outer side Y2 of the bead core 26 (or the bead filler 28) is the tire radial direction from the winding end 18E of the carcass ply 18. Located on the inner side Z1.

  Each of the first fiber reinforcement layer 34 and the second fiber reinforcement layer 36 is a reinforcement layer formed by covering a first organic fiber cord 35 such as a nylon fiber cord and a second organic fiber cord 37 with a topping rubber. The bead core 26 is provided so as to overlap the outer surface of the metal reinforcing layer 34 on the outer side Y2 in the tire axial direction.

  The first fiber reinforcing layer 34 is wound from the tire axial direction inner side Y1 to the outer side Y2 outside the metal reinforcing layer 32, and is provided on the outer surface so as to wrap the metal reinforcing layer 32. In this example, the first fiber reinforcement layer 34 is provided so as to overlap the metal reinforcement layer 32 on the tire radial inner side Z1 and the tire axial direction inner side Y1 of the bead core 26, and on the tire axial direction outer side Y2 of the bead core 26. The second fiber reinforcement layer 36 provided along the outer side of the second fiber reinforcing layer 36 is provided so as to overlap the outer side.

  In the first fiber reinforcement layer 34, the tire radial outer end 34Ein located on the tire axial inner side Y1 of the bead core 26 (or the bead filler 28) is located on the tire radial outer side Z2 from the tire radial outer end 32Ein of the metal reinforcing layer 32. It is located and is arrange | positioned in the position which does not overlap with the tire radial direction outer side end 32Ein of the metal reinforcement layer 32. FIG. In this example, the difference between the distance from the normal L to the tire radial direction outer end 34Ein of the first fiber reinforcement layer 34 and the distance from the normal L to the tire radial direction outer end 32Ein of the metal reinforcement layer 32 is as follows. The extension amount H1 of the first fiber reinforcement layer 34 represented is set to be three times or more the thickness W of the metal reinforcement layer 32 (the thickness when the metal cord 33 is covered with the topping rubber) W.

  Further, the first fiber reinforcement layer 34 has a tire radial outer end 34Eout positioned on the tire axially outer side Y2 of the bead core 26 (or the bead filler 28), the tire radial outer end 32Eout of the metal reinforcing layer 32 and the carcass ply 18. It is preferably located at the outer side Z2 in the tire radial direction from the winding end 18E and terminated at a position of 70% or less of the height H0 (see FIG. 1) in the tire radial direction Z from the nominal diameter to the maximum tire width position.

  The second fiber reinforcement layer 36 is provided so as to cover the tire radial direction outer end 32Eout of the metal reinforcement layer 32 from the outside in the tire axial direction outer side Y2 of the bead core 26 (or the bead filler 28). It extends in the tire radial direction outward Z2 beyond the direction outer end 32Eout. In this example, the second fiber reinforcement layer 36 has a tire radial outer end 36 </ b> E disposed outside the tire radial outer end 34 </ b> Eout of the first fiber reinforcement layer 34, and the tire of the first fiber reinforcement layer 34. It arrange | positions in the position which does not overlap with the radial direction outer side end 34Eout. Further, the second fiber reinforcement layer 36 is disposed only on the outer side Y <b> 2 of the bead core 26 in the tire axial direction, and is not wound inside the bead core 26.

  A reinforcing rubber layer 38 is provided along the main body portion 18 </ b> A of the carcass ply 18 on the tire axially inner side Y <b> 1 of the bead core 26. The reinforcing rubber layer 38 is interposed between the main body portion 18 of the carcass ply 18 and the metal reinforcing layer 32 at the tire radial inner side Y1 from the tire radial outer end 32Ein of the metal reinforcing layer 32, and the first fiber reinforcing layer. 34 is interposed between the main body portion 18 of the carcass ply 18 and the first fiber reinforcement layer 34 at the tire radial direction outer end 34Ein. The reinforcing rubber layer 38 extends from the tire radial direction outer end 34Ein of the first fiber reinforcing layer 34 to the tire radial direction outer side, and the tire radial direction outer end 38E of the reinforcing rubber layer 38 has the first fiber reinforcement. The tire 34 is located on the outer side in the tire radial direction from the tire radial outer end 34Ein of the layer 34. In this example, the distance from the normal L to the tire radial outer end 38E of the reinforcing rubber layer 38 and the normal fiber L to the first fiber reinforcement The extension amount H2 of the reinforcing rubber layer 38 expressed by the difference from the distance to the tire radial direction outer end 34Ein of the layer 34 is set to be not less than three times the thickness W of the metal reinforcing layer 32.

  The inclination angle and the inclination direction of the cords 33, 35, and 37 included in the metal reinforcement layer 32, the first fiber reinforcement layer 34, and the second fiber reinforcement layer 36 provided in the bead portion 18 are set as follows. Yes.

  3 shows the metal cord 33 with respect to the ply cord 19 of the carcass ply 18 in the state where the carcass ply 18, the metal reinforcing layer 32, the first fiber reinforcing layer 34, and the second fiber reinforcing layer 36 in the bead portion 12 are unfolded. The inclination angle and inclination direction of the first organic fiber cord 35 and the second organic fiber cord 37 are shown. As shown in FIG. 3, the metal cord 33 included in the metal reinforcing layer 32 is inclined at an inclination angle of angle θ1 with respect to the ply cord 19 of the carcass ply 18 (that is, with respect to a direction perpendicular to the tire circumferential direction F). The first organic fiber cord 35 of the first fiber reinforcement layer 34 is arranged at an inclination angle of the angle θ2 with respect to the ply cord 19, and the second organic fiber cord of the second fiber reinforcement layer 36 is provided. The fiber cord 37 is disposed to be inclined with respect to the ply cord 19 at an inclination angle of angle θ3.

  The inclination angle θ1 of the metal cord 33 is set larger than the inclination angle θ2 of the first organic fiber cord 35 included in the first fiber reinforcement layer 34 and the inclination angle θ3 of the second organic fiber cord 37 included in the second fiber reinforcement layer 36. ing. That is, the metal cord 33 is inclined in a direction along the tire circumferential direction F as compared with the first organic fiber cord 35 and the second organic fiber cord 37.

  In addition, the inclination direction G1 of the first organic fiber cord 35 included in the first fiber reinforcement layer 34 with respect to the ply cord 19 is the metal cord 33 included in the metal reinforcement layer 32 and the second organic fiber cord 37 included in the second fiber reinforcement layer 36. And the metal cord 33 and the second fiber reinforcing layer 36 are inclined in the opposite direction with the ply cord 19 interposed therebetween.

  Here, the angle of the metal cord 33, the first organic fiber cord 35, and the second organic fiber cord 37, the thickness W of the metal reinforcing layer 32, the extension amount H1 of the first fiber reinforcing layer 34, and the extension of the reinforcing rubber layer 38 As an example of the amount H2, the inclination angle θ1 of the metal cord 33 is in the range of 50 ° to 70 °, the inclination angle θ2 of the first organic fiber cord 35 is in the range of −40 ° to −60 °, and the second organic When the inclination angle θ3 of the fiber cord 37 can be set in the range of 40 ° to 60 °, and the thickness W of the metal reinforcing layer 32 is 1.5 mm to 4.0 mm, the extension of the first fiber reinforcing layer 34 The protruding amount H1 can be set to 5.0 mm to 20 mm, and the extending amount H2 of the reinforcing rubber layer 38 can be set to 5.0 mm to 20 mm.

  In the present embodiment as described above, the inclination angle θ1 of the metal cord 33 is the inclination angle θ2 of the first organic fiber cord 35 included in the first fiber reinforcement layer 34 and the second organic fiber cord included in the second fiber reinforcement layer 36. 37, the metal reinforcing layer 32 and the first fiber reinforcing layer 34 wound around the bead core 26 are set in an inclination direction G2 of the metal cord 33 with respect to the ply cord 19 and the first fiber reinforcing layer. The inclination direction G1 of 35 inclines in the opposite direction.

  Therefore, by arranging the metal cord 33 along the tire circumferential direction F as compared with the first organic fiber cord 35 and the second organic fiber cord 37, the metal reinforcement layer 32 can be enhanced while enhancing the reinforcement effect. The first organic fiber cords 35 of the first fiber reinforcement layer 34 arranged so as to overlap with the metal 32 are inclined in the opposite direction with the metal cord 33 and the ply cord 19 of the metal reinforcement layer 32 interposed therebetween, whereby the metal reinforcement layer 32 and the first The reinforcing effect of the portion in which the one-fiber reinforcing layer 34 is arranged in an overlapping manner can be enhanced. That is, in this embodiment, the reinforcing effect around the bead core 26 can be enhanced while the metal reinforcement layer 32 and the first fiber reinforcement layer 34 are provided thin to suppress an increase in the thickness around the bead core 26.

  In particular, in this embodiment, the metal reinforcing layer 32 and the first fiber reinforcing layer 34 are provided not only on the tire axis direction outer side Y2 of the bead core 26 but also on the inner side Y1, and the periphery of the bead core 26 is reinforced in a well-balanced manner. Therefore, it is possible to suppress the thickness of various members such as a reinforcing layer provided on the outer side Y2 of the bead core 26 in the tire axial direction, and increase in the thickness around the bead core 26 can be suppressed.

  Further, in the tire axially inner side Y1 of the bead core 26, the radially outer end 34Ein of the first fiber reinforcing layer 34 extends from the radially outer end 32Ein of the metal reinforcing layer 32 to the outer side in the tire radial direction. By reducing the reinforcing effect by the 32 and the first fiber reinforcing layer 34 stepwise as it goes outward in the tire radial direction, strain concentrated on the radially outer end 32Ein of the metal reinforcing layer 32 can be alleviated, and the bead portion 12 durability can be improved.

  In the present embodiment, the extension amount H1 of the first fiber reinforcement layer 34 and the extension amount H2 of the reinforcement rubber layer 38 are set to be three times or more the thickness W of the metal reinforcement layer 32. The outer side of the tire radial direction outer end 32Ein of the layer 32 can be reliably covered with the first fiber reinforcing layer 34, and the reinforcing effect by the reinforcing layers 32, 34 can be reduced in stages, and the metal reinforcing layer 32 The occurrence of air accumulation at the tire radial direction outer end 32Ein and the tire radial direction outer end 34Ein of the first fiber reinforcement layer 34 can be suppressed.

  Further, on the outer side Y2 of the bead core 26 in the tire axial direction, the first fiber reinforcing layer 34 and the second fiber reinforcing layer 36 are disposed so that the organic fiber cords 35 and 37 are inclined in the opposite directions to each other. The thin fiber layer 1 and the second fiber layer 36 are provided to suppress an increase in the thickness Y2 of the bead core 26 in the tire axial direction. Reinforcement can be emphasized.

  In the present embodiment, a reinforcing rubber layer 38 is provided between the metal reinforcing layer 32 and the main body portion 18A of the carcass ply 18 on the tire axially inner side Y1 of the bead core 26, and the tire of the reinforcing rubber layer 38 is provided. The radially outer end 38E extends from the outer end in the tire radial direction of the first fiber reinforcement layer to the outer side in the tire radial direction. Therefore, in addition to the reinforcing effect by the reinforcing rubber layer 38, the tension between the metal reinforcing layer 32 and the first fiber reinforcing layer 34 and the carcass ply 18 is caused by the tension in the tire radial direction Z2 generated in the main body portion 18A of the carcass ply 18. The generated shear strain can be relaxed by the reinforcing rubber layer 38, and the durability of the bead portion 12 can be improved.

(Second Embodiment)
FIG. 4 is a cross-sectional view of the bead portion 12 of the pneumatic radial tire according to the second embodiment, and FIG. 5 is an inclination of the cord included in each reinforcing layer with respect to the ply cord in the pneumatic radial tire according to the second embodiment. It is a schematic diagram which shows an angle and an inclination direction, (a) is a metal cord, (b) is a 1st organic fiber cord, (c) has shown the 2nd organic fiber cord. The second embodiment differs from the first embodiment in that the angle of the first organic fiber cord 35 of the first fiber reinforcement layer 34 with respect to the ply cord 19 changes in the tire axial direction Y.

  Specifically, the first fiber reinforcement layer 34 includes a folded portion 34R positioned around the bead core 26, and an extended portion extending from the folded portion 34R to the outer side in the tire radial direction Z2, in other words, the tire from the folded portion 34R. An extending portion 34S extending to the inner side Y1 in the axial direction and an extending portion 34T extending to the outer side Y2 in the tire axial direction are provided.

  The first fiber reinforcing layer 34 has an extension portion in which the first organic fiber cord 35R in the turn-up portion 34R is inclined at an angle θ2R with respect to the ply cord 19 and extends from the turn-up portion 34R to the inner side Y1 in the tire axial direction. The first organic fiber cord 35S in 34S is inclined with respect to the ply cord 19 at an inclination angle of θ2S, and the first organic fiber cord 35T in the extended portion 34T extending from the folded portion 34R to the outer side Y2 in the tire axial direction is the ply. The cord 19 is inclined at an angle θ2T.

  The inclination angle θ2R of the first organic fiber cord 35R in the folded portion 34R is smaller than the inclination angle θ1 of the metal cord 33 of the metal reinforcing layer 32, and the inclination angle θ2S of the first organic fiber cord 35S in the extension portion 34S. In addition, the inclination angle θ2T of the first organic fiber cord 35T in the extending portion 34T is set to be larger than the inclination angle θ1 of the metal cord 33, for example, in the range of 50 ° to 70 °, and the first organic fiber in the folded portion 34R. The inclination angle θ2R of the cord 35R is in the range of −40 ° to −60 °, and the inclination angles θ2S and θ2T of the first organic fiber cords 35S and 35T in the extending portions 34S and 34T are in the range of −30 ° to −50 °. Each can be set.

  As described above, in the first fiber reinforcement layer 34, the inclination angle θ2R of the first organic fiber cord 35 in the folded portion 34R is set to be larger than the inclination angles θ2S and θ2T of the first organic fiber cord 35 in the extending portions 34S and 34T. The first organic fiber cord 35 is inclined in the direction along the tire circumferential direction F in the folded portion 34R as compared with the extending portions 34S and 34T. Therefore, the reinforcing effect by the first fiber reinforcing layer 34 can be reduced stepwise as it goes to the outer side Z2 in the tire radial direction, and the durability of the bead portion 12 can be improved.

  About 2nd Embodiment, the other structure and effect are the same as 1st Embodiment, and description is abbreviate | omitted.

(Other embodiments)
In the first embodiment, the reinforcing rubber layer 38 is provided along the main body portion 18A of the carcass ply 18. However, as shown in FIG. 6, the metal reinforcing layer 32 and the first fiber reinforcement are not provided without the reinforcing rubber layer 38. The end of the tire radial direction outer side Z2 of the layer 34 may be provided so as to overlap the main body 18A of the carcass ply 18.

  Further, the second fiber reinforcing layer 36 may be provided so as to be wound up from the tire axial direction inner side Y1 to the outer side Y2 outside the metal reinforcing layer 32. In that case, the tire radial direction outer side end of the second fiber reinforcement layer 36 is located in the tire radial direction inner side Z1 from the tire radial direction outer end 32Ein of the metal reinforcement layer 32 in the tire axial direction inner side Y1 of the bead core 26.

  Since the pneumatic radial tire according to the present embodiment is excellent in durability of the bead portion, the pneumatic radial tire is suitable as a heavy-duty pneumatic tire used for vehicles with heavy vehicle mass such as trucks, buses, industrial vehicles, and construction vehicles.

  Although some embodiments have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention.

  An evaluation method in which a pneumatic radial tire (size: 275 / 80R22.5, rim: 22.5 × 8.25) was prototyped and performance evaluation was performed in order to specifically show the configuration and effects of the above embodiment. Is as follows.

(1) Durability of bead part The inner pressure of 900 kPa is filled into the rim-assembled tire, it is crimped on a steel drum with a smooth surface of 1.7m radius with 210% of JATMA standard load, and run at 40km / h for 168 hours. It was. The load was increased by 10% every 168 hours and the vehicle was run until the bead portion broke. The room temperature was set to 40 ° C. The time until destruction was expressed as an index with Comparative Example 1 taken as 100. The larger the value, the better the durability.

(2) Rolling resistance Based on ISO28580, the tire rolling resistance value was measured. The index was expressed as an index with Comparative Example 1 as 100. The smaller the value, the better.

  Table 1 shows configurations of tires according to Examples 1 to 3 and Comparative Examples 1 and 2. Example 1 is an example having the bead part configuration shown in FIGS. 2 and 3 according to the first embodiment, and Example 2 is the bead part configuration shown in FIGS. 4 and 5 according to the second embodiment. Example 3 is an example having the bead portion configuration shown in FIG. 6 according to the other embodiment described above. Comparative Examples 1 and 2 are based on the bead configuration shown in FIG. 2 as in Example 1, but the inclination angle and inclination direction of the first organic fiber cord 35 of the first fiber reinforcement layer 34 are the same. This is outside the scope of the invention. In the table, the inclination direction G2 is indicated by plus and the inclination direction G1 is indicated by minus.

  The results are as shown in Table 1. In Examples 1 to 3, the rolling resistance was reduced and the durability of the bead portion was improved while suppressing the increase in the thickness of the bead portion as compared with Comparative Examples 1 and 2. . In particular, in Example 1 in which the reinforcing rubber layer 38 is provided along the main body portion 18A of the carcass ply 18, the inclination angle θ2R of the first organic fiber cord 35R in the folded portion 34R is the first organic in the extending portions 34S and 34T. In Example 2 in which the inclination angles θ2S and θ2T of the fiber cords 35S and 35T were set larger, the durability of the bead portion was significantly improved.

DESCRIPTION OF SYMBOLS 10 ... Pneumatic radial tire, 12 ... Bead part, 14 ... Side wall part, 16 ... Tread part, 18 ... Carcass ply, 18 ... Main part, 18B ... Winding part, 20 ... Belt, 22 ... Inner liner, 24 ... Side Wall rubber, 26 ... bead core, 28 ... bead filler, 32 ... metal reinforcing layer, 33 ... metal cord, 34 ... first fiber reinforcing layer, 35 ... organic fiber cord, 36 ... second fiber reinforcing layer, 37 ... organic fiber cord 38 ... Reinforced rubber layer

Claims (6)

A carcass ply including a bead core embedded in a bead portion, a bead filler disposed on the outer side in the tire radial direction of the bead core, a ply cord wound around the bead core from the inner side in the tire axial direction, and the carcass ply; A metal reinforcing layer including a metal cord wound outward from the inside in the tire axial direction on the outer side of the tire, and a first fiber reinforcing layer including an organic fiber cord wound outward from the inner side in the tire axial direction on the outer side of the metal reinforcing layer A second fiber reinforcing layer including an organic fiber cord provided at least on the outer side in the tire axial direction from the bead core,
An angle of the metal cord provided in the metal reinforcing layer with respect to the ply cord is larger than an angle of the organic fiber cord provided in the first fiber reinforcing layer and the second fiber reinforcing layer with respect to the ply cord, and the first with respect to the ply cord. A pneumatic radial characterized in that an inclination direction of an organic fiber cord of one fiber reinforcement layer is inclined in a direction opposite to an inclination direction of an organic fiber cord provided in the metal reinforcement layer and the second fiber reinforcement layer. tire.   On the inner side in the tire axial direction of the bead core, the outer end in the tire radial direction of the metal reinforcing layer is located on the outer side in the tire radial direction from the normal line of the inner surface of the tire passing through the winding end of the carcass ply, and the tire axial direction of the bead core 2. The pneumatic tire according to claim 1, wherein an outer end in the tire radial direction of the first fiber reinforcement layer located on an inner side is located on an outer side in the tire radial direction from an outer end in the tire radial direction of the metal reinforcement layer. Radial tire.   A tire having a reinforcing rubber layer provided between the metal reinforcing layer and the carcass ply on the inner side in the tire axial direction of the bead core, wherein the outer end in the tire radial direction of the reinforcing rubber layer is the tire of the first fiber reinforcing layer. 3. The pneumatic radial tire according to claim 2, wherein the pneumatic radial tire is located on an outer side in a tire radial direction from a radially outer end. The second fiber reinforcing layer is wound up from the inner side in the tire axial direction outside the metal reinforcing layer,
The tire radial direction outer side end of the said 2nd fiber reinforcement layer is located in a tire radial direction inner side from the tire radial direction outer side end of the said metal reinforcement layer in the tire axial direction inner side of the said bead core. Or a pneumatic radial tire according to any one of 3 above.   The first fiber reinforcing layer includes the ply of the organic fiber cord in an extension portion positioned at an outer side in the tire radial direction of the organic fiber cord in the folded portion positioned around the bead core. The pneumatic radial tire according to any one of claims 1 to 4, wherein the pneumatic radial tire is larger than an angle with respect to the cord.   The winding end of the carcass ply is located on the outer side in the tire radial direction of the metal reinforcing layer on the outer side in the tire radial direction of the bead core. Pneumatic radial tire described in 2.

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