JP2012046156A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic radial tire suppressing failures at a carcass folded end part and at a tire radial direction outside end part of a reinforcing layer.SOLUTION: At least a reinforcing layer 9 in which an organic fiber cord or a metal cord is coated with a rubber material is provided at the tire width direction outside of the carcass folded end part 6a. In a non-load state of the tire in which the tire is mounted on a normal rim and normal internal pressure is filled, the reinforcing layer 9 includes a first reinforcing part 9a which is located nearer the tire radial direction outside than the carcass folded end part 6a and at a tire radial direction outermost part of the reinforcing layer 9, and a second reinforcing part 9b which is arranged in a region in the vicinity of the carcass folded end part 6a and includes a tire radial direction position including at least the carcass folded end part 6a. The first reinforcing part 9a and the second reinforcing part 9b are adjacent to each other or overlapped with each other. A cord angle α formed by the organic fiber cord or the metal cord of the first reinforcing part 9a in relation to a tire peripheral direction and a cord angle β formed by the organic fiber cord or the metal cord of the second reinforcing part 9b in relation to the tire peripheral direction satisfy α is less than β.

Description

  The present invention relates to a pneumatic radial tire. More specifically, the pneumatic radial tire of the present invention relates to a pneumatic radial tire with improved travel distance and the like.

  For radial tires for heavy loads, a technique is used in which a reinforcing layer containing an organic fiber cord or a metal cord is disposed on the outer side in the tire width direction of the end portion in order to alleviate distortion at the end portion of the carcass folded back.

For example, Patent Document 1 discloses a cord angle α _U with respect to the tire circumferential direction of the reinforcing layer at the tread side end portion of the reinforcing layer, and a cord angle α _L with respect to the tire circumferential direction of the reinforcing layer at a portion other than the tread side end portion. , Α _U > α _L , and in particular, a pneumatic tire is disclosed in which the cord is bent by increasing the angle α (°) at a position 1/3 h from the upper end of the reinforcing layer (Patent Document 1). 5 to 7). According to this pneumatic tire, the angle α _L formed by the cord with respect to the tire circumferential direction in the tire radial direction inner region of the reinforcing layer is reduced by making α _U and α _L different to form a composite angle structure. Thus, the rigidity in the tire circumferential direction can be increased, thereby improving the casing rigidity.

JP-A-6-1127

  However, the pneumatic tire disclosed in Patent Document 1 has a large cord angle formed by the cord of the reinforcing layer with respect to the tire circumferential direction in the outer region in the tire radial direction of the reinforcing layer. For this reason, there is a possibility that strain concentrates on the outer region in the tire radial direction, and the outer region may become a starting point of occurrence of the failure, which may promote the failure in the vicinity of the carcass folding end portion.

  This invention is made | formed in view of said situation, and it aims at providing the pneumatic radial tire which suppressed the failure of the carcass folding | turning edge part and the tire radial direction outer edge part of a reinforcement layer.

  In order to solve the above-described problems and achieve the object, the pneumatic radial tire according to the present invention has at least one layer in which an organic fiber cord or a metal cord is coated with a rubber material on the outer side in the tire width direction of the carcass folded end portion. In a no-load state in which the reinforcing layer is mounted on a regular rim and filled with a regular internal pressure, the reinforcing layer is on the outer side in the tire radial direction from the carcass folded end and on the outermost side in the tire radial direction of the reinforcing layer. A first reinforcing portion that is positioned, and a second reinforcing portion that is disposed in a region in the vicinity of the carcass folded end portion and that includes at least a carcass folded end portion in a tire radial direction position, the first reinforcing portion and the second reinforcing portion. A cord angle α formed by the organic fiber cord or the metal cord of the first reinforcing portion with respect to a tire circumferential direction, and the organic fiber cord of the second reinforcing portion. The code angle beta to the metal cord with respect to the tire circumferential direction, is set to satisfy the alpha <beta.

  In the pneumatic radial tire of the present invention, the cord angle of the reinforcing layer is different between the first reinforcing portion and the second reinforcing portion. That is, in the pneumatic radial tire of the present invention, the cord angle α formed by the organic fiber cord or metal cord in the first reinforcing portion with respect to the tire circumferential direction is the organic fiber cord or metal cord in the second reinforcing portion. Is smaller than the cord angle β. For this reason, while the rigidity in the tire radial direction is ensured in the region near the carcass folded end by the second reinforcing portion, the reinforcement is provided in the region radially outside the carcass folded end by the first reinforcing portion. Shear strain in the outermost layer in the tire radial direction of the layer (hereinafter referred to as “tire radial direction outer region” as necessary) can be reduced. As a result, the shear strain promoted at the carcass folded end due to the shear strain can be reduced. Therefore, according to the pneumatic radial tire of the present invention, it is possible to suppress failure of the carcass folded end portion and the outer end portion in the tire radial direction of the reinforcing layer.

  In the pneumatic radial tire according to the present invention, the innermost portion in the tire radial direction of the first reinforcing portion may be a position that is a distance of 0.5 × (H + Hc) or more and less than the tire radial distance H from the center of gravity of the bead core. desirable. In this pneumatic radial tire, the tire innermost radial direction of the first reinforcing portion is a tire radial distance Hc from the center of gravity of the bead core to the carcass folded end and the center of gravity of the bead core to the outermost radial direction of the reinforcing layer. It exists in the position more than the distance 0.5 times the sum with radial direction distance H, and exists in the position below the tire radial direction distance H from the gravity center of a bead core to the tire radial direction outermost part of a reinforcement layer.

  By setting the innermost portion in the tire radial direction of the first reinforcing portion to a position not less than 0.5 times the sum of the tire radial direction distance Hc and the tire radial direction distance H from the center of gravity of the bead core, the second reinforcing portion is Sufficiently secure, and thereby sufficient rigidity in the tire radial direction can be ensured. In addition, by setting the innermost portion in the tire radial direction of the first reinforcing portion at a position less than the tire radial distance H from the center of gravity of the bead core, the first reinforcing portion is secured and shear strain in the outer region in the tire radial direction is reduced. can do. As a result, the shear strain promoted at the carcass folded end due to the shear strain can be reduced. Therefore, according to the pneumatic radial tire having such a configuration, failure of the carcass folded end portion and the tire radial direction outer end portion of the reinforcing layer can be suppressed.

  In the pneumatic radial tire of the present invention, it is desirable that the first reinforcing portion has a width in the tire radial direction of at least 5 mm. By setting the width of the first reinforcing portion in the tire radial direction to at least 5 mm, it is possible to sufficiently secure the first reinforcing portion and further reduce the shear strain in the tire radial direction outer region. As a result, the shear strain promoted by the carcass folded end due to the shear strain can be further reduced. Therefore, according to the pneumatic radial tire of the present invention, it is possible to further suppress the failure of the carcass folded end portion and the outer end portion in the tire radial direction of the reinforcing layer.

  In the pneumatic radial tire of the present invention, it is preferable that the second reinforcing portion is disposed in a region from 0.9 × Hc to 1.1 × Hc from the center of gravity of the bead core. By arranging the second reinforcing portion in the region of 0.9 × Hc or more and 1.1 × Hc or less from the center of gravity of the bead core, at least in this region, the rigidity in the tire radial direction is ensured by the second reinforcing portion. Can do.

  Further, in the pneumatic radial tire of the present invention, a single reinforcing layer has the first reinforcing portion and the second reinforcing portion, and the first reinforcing portion and the second reinforcing portion are at these boundary portions. It is desirable to have a cord bend. Since the single reinforcing layer has the first reinforcing portion and the second reinforcing portion, and the first reinforcing portion and the second reinforcing portion have the cord bent portion at the boundary portion thereof, the cord having the cord angle α and the cord angle can be obtained. β cords can be continuously extended into one reinforcing layer. For this reason, the rigidity of the reinforcing layer can be continuously changed without abruptly changing in the tire radial direction, so that a failure at a place where the cord angles α and β change can be suppressed.

  In the pneumatic radial tire of the present invention, a plurality of the reinforcing layers include a first reinforcing layer having the first reinforcing portion and a second reinforcing layer having the second reinforcing portion, and the first reinforcing layer and the It is desirable that the second reinforcing layer is partially laminated. The plurality of reinforcing layers includes a first reinforcing layer having a first reinforcing portion and a second reinforcing layer having a second reinforcing portion, and the first reinforcing layer and the second reinforcing layer are partially laminated to reinforce. The production of the layer can be simplified. For this reason, the manufacturing efficiency of a pneumatic radial tire can be improved.

  In the pneumatic radial tire of the present invention, the reinforcing layer further includes a third reinforcing portion, and the third reinforcing portion is disposed in a region not more than a tire radial distance Hc from the center of gravity of the bead core. A cord angle γ formed by the organic fiber cord or the metal cord of the reinforcing portion with respect to the tire circumferential direction, and a cord angle β formed by the organic fiber cord or the metal cord of the second reinforcing portion with respect to the tire circumferential direction. However, it is desirable that γ <β is satisfied.

  In this pneumatic radial tire, the cord angles of the reinforcing layers are made different between the third reinforcing portion and the second reinforcing portion. That is, in this pneumatic radial tire, the cord angle γ formed by the organic fiber cord or the metal cord in the third reinforcing portion with respect to the tire circumferential direction is the organic fiber cord or metal cord in the second reinforcing portion with respect to the tire circumferential direction. Is smaller than the cord angle β. For this reason, it is possible to improve the rigidity in the tire circumferential direction in the region not more than the distance Hc in the tire radial direction from the center of gravity of the bead core, while securing the rigidity in the tire radial direction by the second reinforcing part. As a result, the casing rigidity can be improved due to the improvement in rigidity in the tire circumferential direction.

  In the pneumatic radial tire of the present invention, it is desirable that a difference in height is provided at the end position of the organic fiber cord or the metal cord on the outer side in the tire radial direction. In the pneumatic radial tire, a part of the plurality of cords does not extend to the outermost portion in the tire radial direction in the outer region in the tire radial direction of the reinforcing layer. Thereby, the cord arrangement density in the tire radial direction outermost part of the tire radial direction outer region of the reinforcement layer is made smaller than the cord arrangement density in other parts of the tire radial direction outer region of the reinforcement layer. . For this reason, the shear strain in the tire radial direction outer side region can be further reduced. As a result, the shear strain promoted by the carcass folded end due to the shear strain can be further reduced. Therefore, according to the pneumatic radial tire of the present invention, it is possible to further suppress the failure of the carcass folded end portion and the outer end portion in the tire radial direction of the reinforcing layer.

  The pneumatic radial tire according to the present invention can suppress the failure of the carcass folded end portion and the outer end portion in the tire radial direction of the reinforcing layer.

FIG. 1 is a meridional cross-sectional view showing a pneumatic radial tire of the present embodiment. FIG. 2 is a diagram illustrating an example of a main part A of the pneumatic radial tire illustrated in FIG. 1 and a cord extending direction of a reinforcing layer. FIG. 3A is a conceptual diagram illustrating an example of the structure of the reinforcing layer illustrated in FIG. 2. 3-2 is a conceptual diagram illustrating an example of a structure of a reinforcing layer illustrated in FIG. FIG. 4 is a diagram illustrating an example of a main part A of the pneumatic radial tire illustrated in FIG. 1 and a cord extending direction of a reinforcing layer. FIG. 5 is a diagram illustrating an example of a main part A of the pneumatic radial tire illustrated in FIG. 1 and a cord extending direction of a reinforcing layer. FIG. 6 is a chart showing the results of a performance test of a pneumatic radial tire according to an example of the present invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following description. The constituent elements in the following description include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range. Furthermore, the configurations disclosed below can be combined as appropriate.

  In the following description, the tire width direction means a direction parallel to the tire rotation axis, the outer side in the tire width direction means the side away from the tire equatorial plane, and the inner side in the tire width direction means the side toward the tire equatorial plane. Means. The tire circumferential direction means a direction rotating around the tire rotation axis as a central axis. The tire radial direction means a direction orthogonal to the tire rotation axis, the tire radial direction outer side means a side away from the tire rotation axis, and the tire radial direction inner side means a side toward the tire rotation axis. The tire equatorial plane means a plane orthogonal to the tire rotation axis and passing through the center of the tire width. The tire equator line means a line along the tire radial direction on the tire equator plane.

  FIG. 1 is a meridional cross-sectional view showing a pneumatic radial tire of the present embodiment. The pneumatic radial tire 1 shown in FIG. 1 is in a no-load state that is mounted on a regular rim and filled with a regular internal pressure. Here, the regular rim is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, a standard rim for JATMA, “Design Rim” for TRA, or ETRTO If so, it means "Measuring Rim". The “regular internal pressure” is the air pressure defined by the standard for each tire. In the case of JATMA, it means the maximum air pressure, and in the case of a passenger car tire, it is 180 kPa. If it is TRA, it means the maximum value described in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES”, and if it is ETRTO, it means “INFLATION PRESSURE”.

  As shown in FIG. 1, the pneumatic radial tire 1 includes a tread portion 2, shoulder portions 3 on both sides of the tread portion 2, and sidewall portions 4 and bead portions 5 successively from the shoulder portions 3. Yes. The pneumatic radial tire 1 includes a carcass 6, a bead protective layer 7, and a belt layer 8, and a reinforcing layer 9 on the outer side in the tire width direction of the carcass 6.

  The tread portion 2 is exposed to the outside of the pneumatic radial tire 1, and the surface thereof is the contour of the pneumatic radial tire 1. A tread surface 21 is formed on the outer peripheral surface of the tread portion 2, that is, on the tread surface that contacts the road surface during traveling. The tread surface 21 is formed with a plurality of circumferential grooves 22 extending in the tire circumferential direction and a plurality of land portions 23 that are partitioned by the circumferential grooves 22. In the present embodiment, seven circumferential grooves 22 including the center of the tread portion 2 in the tire width direction and including the position of the crown center CL on the tire equatorial plane C are formed. The rib 23 is formed.

  The shoulder portion 3 is a portion on both outer sides in the tire width direction of the tread portion 2. Further, the sidewall portions 4 are exposed on both outer sides in the tire width direction of the pneumatic radial tire 1. The bead portion 5 includes a bead core 51, a hard bead filler 52, and a soft bead filler 53. The bead core 51 is formed by winding a bead wire, which is a steel wire, in a ring shape. The bead fillers 52 and 53 are disposed in a space formed by folding the carcass 6 outward in the tire width direction at the position of the bead core 51.

  The carcass 6 is formed of an organic fiber or steel coated with a rubber material, and the cord is arranged along the tire circumferential direction of the pneumatic radial tire 1 in a mode perpendicular to the tire equator line of the pneumatic radial tire 1. It is installed. The carcass 6 is bridged in a toroidal shape from the tread portion 2 to the bead core 51 of the bead portion 5 via the shoulder portions 3 and the sidewall portions 4 on both sides thereof in the tire width direction. The bead protective layer 7 is formed of organic fiber or steel coated with a rubber material, and the cord is arranged so as to wrap the carcass 6 in the bead portion 5 in a manner perpendicular to the tire equator line of the pneumatic radial tire 1. It is installed. The end portion of the bead protective layer 7 on the outer side in the tire width direction is located on the inner side in the tire radial direction than the end portion of the carcass 6 on the outer side in the tire width direction.

  The belt layer 8 is provided on the outer side in the tire radial direction than the carcass 6 in the tread portion 2. The belt layer 8 is formed by laminating a plurality of belts formed of organic fibers or steel covered with a rubber material, and covers the carcass 6 along the tire circumferential direction. In the present embodiment, the belt layer 8 is laminated in the order of the first belt 81, the second belt 82, the third belt 83, the fourth belt 84, and the fifth belt 85 from the inner side in the tire radial direction to the outer side in the tire radial direction. It has a five-layer structure.

  The reinforcing layer 9 is provided on the outer side in the tire width direction of the folded portion of the carcass 6, and the end portion on the outer side in the tire radial direction is a tire diameter than the end portion in the tire radial direction (turned end portion 6 a) of the carcass 6. It is located outside in the direction. The reinforcing layer 9 is a cord layer in which a plurality of organic fiber cords or metal cords are arranged and rolled and covered with a rubber material.

  In the example shown in FIG. 1, the reinforcing layer 9 is one layer, but the present embodiment is not limited to this and may be a plurality of layers. When the reinforcing layer 9 has a plurality of layers, it is preferable that the organic fiber cords or metal cords of the reinforcing layer 9 cross each other in order to increase the bead portion rigidity. However, the reinforcing layer 9 in the present embodiment is not limited to such a mode, and includes a mode in which the cords do not cross each other.

  The pneumatic radial tire 1 configured as described above has a bead portion 5 configured as follows. FIG. 2 is a diagram illustrating an example of a main part A of the pneumatic radial tire illustrated in FIG. 1 and a cord extending direction of a reinforcing layer. In FIG. 2, the left figure is a view from a tire meridian cross section as in FIG. 1, and the right figure is a view from a tire side view. Moreover, the left figure and the right figure of FIG. 2 respond | correspond in a tire radial direction, and this correspondence is shown with the dotted line.

  2, Hc is a tire radial direction distance from the center of gravity 51a of the bead core to the carcass folding end portion 6a, and Hu is a cord bending portion that changes from the center of gravity 51a of the bead core to the cord angle α from the cord angle β. The tire radial direction distance to X, and H is the tire radial direction distance from the center of gravity 51a of the bead core to the outermost portion of the reinforcing layer 9 in the tire radial direction.

  As shown in the left diagram of FIG. 2, the reinforcing layer 9 is formed substantially parallel to the extending direction of the carcass 6 on the outer side in the tire width direction of the carcass folded end portion 6a in the tire meridian cross-sectional view. Here, the carcass folding end portion means a carcass folding end portion extending to the outermost side in the tire radial direction among one or a plurality of carcasses. In the example shown in the left diagram of FIG. Means the folded end 6a.

  The pneumatic radial tire 1 of the present embodiment includes a first reinforcing portion 9a in which the reinforcing layer 9 is located on the outer side in the tire radial direction of the carcass folded end portion 6a and on the outermost portion in the tire radial direction of the reinforcing layer 9, and the carcass A second reinforcing portion 9b including a carcass folded end portion 6a is disposed in a region in the vicinity of the folded end portion, and the position in the tire radial direction includes at least the carcass folded end portion 6a. The 1st reinforcement part 9a and the 2nd reinforcement part 9b adjoin or overlap.

  The pneumatic radial tire 1 of the present embodiment includes a cord angle α formed by the organic fiber cord or the metal cord of the first reinforcing portion 9a with respect to the tire circumferential direction, as shown in the right view of FIG. The cord angle β formed by the organic fiber cord or metal cord 9b with respect to the tire circumferential direction satisfies α <β.

  In the pneumatic radial tire 1 of the present embodiment, the reinforcing layer 9 includes a first reinforcing portion 9a in a tire radial direction outer region and a second reinforcing portion 9b in a region in the vicinity of the carcass folded end portion 6a. The cord angle α of the reinforcing portion 9a is different from the cord angle β of the second reinforcing portion 9b. That is, in the pneumatic radial tire 1 shown in FIG. 2, the cord angle α formed by the organic fiber cord or the metal cord in the first reinforcing portion 9a with respect to the tire circumferential direction is the organic fiber cord or the metal cord in the second reinforcing portion 9b. Is smaller than the cord angle β formed with respect to the tire circumferential direction. Therefore, the second reinforcing portion 9b of the reinforcing layer 9 ensures the tire radial rigidity in the region near the carcass folded end portion 6a, and the first reinforcing portion 9a of the reinforcing layer 9 allows the tire radial outer region. It is possible to reduce the shear strain in As a result, the shear strain promoted by the carcass folded end portion 6a due to the shear strain can be reduced. Therefore, according to the pneumatic radial tire 1 of the present embodiment, failure of the carcass folded end portion 6a and the outer end portion in the tire radial direction of the reinforcing layer 9 can be suppressed.

  In the pneumatic radial tire 1 of the present embodiment, the cord angle α preferably satisfies 0 ° <α ≦ 20 °. By satisfying 0 ° <α, the rigidity in the tire radial direction in the outer region in the tire radial direction of the reinforcing layer 9 can be ensured. Further, by satisfying α ≦ 20 °, it is possible to further reduce the shear strain in the outer region in the tire radial direction of the reinforcing layer 9. As a result, the shear strain promoted by the carcass folded end portion 6a due to the shear strain can be further reduced. Therefore, according to the pneumatic radial tire 1 having such a configuration, it is possible to further suppress the failure of the carcass folded end portion 6a and the outer end portion in the tire radial direction of the reinforcing layer 9.

  In the pneumatic radial tire 1 of the present embodiment, it is more preferable that the cord angle β satisfies 30 ° <β ≦ 60 °. By satisfying 30 ° <β, it is possible to further reduce the shear strain in the region in the vicinity of the carcass folded end portion 6a of the reinforcing layer 9. As a result, the shear strain promoted by the carcass folded end portion 6a due to the shear strain can be further reduced. Therefore, according to the pneumatic radial tire 1 having such a configuration, it is possible to further suppress the failure of the carcass folded end portion 6a and the outer end portion in the tire radial direction of the reinforcing layer. Further, by satisfying α ≦ 60 °, the rigidity in the tire circumferential direction can be improved. As a result, it is possible to improve the casing rigidity due to the improvement in the rigidity in the tire circumferential direction.

  In the pneumatic radial tire 1 of the present embodiment, as shown in FIG. 2, the innermost portion in the tire radial direction of the first reinforcing portion 9a is at least 0.5 × (H + Hc) away from the center of gravity of the bead core. It is preferable that the position is less than. By setting the innermost portion in the tire radial direction of the first reinforcing portion 9a to a position at least 0.5 times the sum of the tire radial direction distance Hc and the tire radial direction distance H from the center of gravity 51a of the bead core, the second reinforcement It is possible to sufficiently secure the portion 9b, thereby ensuring sufficient rigidity in the tire radial direction. Further, by setting the innermost portion in the tire radial direction of the first reinforcing portion 9a to a position less than the tire radial direction distance H from the center of gravity 51a of the bead core, the first reinforcing portion 9a is secured and shearing in the tire radial outer region is performed. Distortion can be reduced. As a result, the shear strain promoted by the carcass folded end portion 6a due to the shear strain can be reduced. Therefore, according to the pneumatic radial tire 1 having such a configuration, it is possible to suppress failure of the carcass folded end portion 6a and the outer end portion in the tire radial direction of the reinforcing layer 9.

  In the pneumatic radial tire 1 of the present embodiment, it is more preferable that the innermost portion in the tire radial direction of the first reinforcing portion 9a is a position not more than a distance of 0.9 × H from the center of gravity 51a of the bead core. By setting the innermost portion in the tire radial direction of the first reinforcing portion 9a to a position not more than 0.9 times the distance H in the tire radial direction from the center of gravity 51a of the bead core, the first reinforcing portion 9a is sufficiently secured, and the tire It is possible to further reduce the shear strain in the radially outer region. As a result, the shear strain promoted by the carcass folded end portion 6a due to the shear strain can be further reduced. Therefore, according to the pneumatic radial tire 1 having such a configuration, it is possible to further suppress the failure of the carcass folded end portion 6a and the outer end portion in the tire radial direction of the reinforcing layer 9.

  In the pneumatic radial tire 1 according to this embodiment, the first reinforcing portion 9a preferably has a width in the tire radial direction of at least 5 mm. By setting the width of the first reinforcing portion 9a in the tire radial direction to at least 5 mm, it is possible to further reduce the shear strain in the outer region in the tire radial direction. As a result, the shear strain promoted by the carcass folded end portion 6a due to the shear strain can be further reduced. Therefore, according to the pneumatic radial tire 1 having such a configuration, it is possible to further suppress the failure of the carcass folded end portion 6a and the outer end portion in the tire radial direction of the reinforcing layer 9.

  In addition, it is preferable to change suitably the width | variety of the tire radial direction of the 1st reinforcement part 9a with tire size. For example, when the tire size is 12R22.5 or more, it is preferable that the tire size is at least 7 mm. The width of the first reinforcing portion 9a in the tire radial direction is preferably changed as appropriate depending on the tire radial direction distance H from the center of gravity 51a of the bead core to the outermost portion of the reinforcing layer 9 in the tire radial direction. For example, when the tire radial distance H is 70 mm or more, it is preferably at least 7 mm.

  In the pneumatic radial tire 1 of the present embodiment, it is preferable that the second reinforcing portion is disposed in a region from 0.9 × Hc to 1.1 × Hc from the center of gravity 51a of the bead core. By disposing the second reinforcing portion in a region from 0.9 × Hc to 1.1 × Hc from the center of gravity 51a of the bead core, at least in this region, the rigidity in the tire radial direction is provided by the second reinforcing portion 9b. Can be secured. More preferably, the second reinforcing portion is arranged in a region from 0.8 × Hc to 1.2 × Hc from the center of gravity 51a of the bead core. By disposing the second reinforcing portion in the region of 0.8 × Hc or more and 1.2 × Hc or less from the center of gravity 51a of the bead core, in the wider region, the second reinforcing portion 9b causes the tire radial direction. Stiffness can be increased.

  The pneumatic radial tire 1 of the present embodiment includes a cord of the reinforcing layer 9 in the first reinforcing portion 9a in the tire radial direction outer region of the reinforcing layer 9 and the second reinforcing portion 9b in the region in the vicinity of the carcass folded end portion 6a. Although the angles α and β are different, the following structure can be adopted as the structure of the reinforcing layer 9.

  3A and 3B are conceptual diagrams illustrating an example of the structure of the reinforcing layer illustrated in FIG. In the pneumatic radial tire 1 of the present embodiment, as illustrated in FIG. 3A, the single reinforcing layer 9 includes a first reinforcing portion 9a and a second reinforcing portion 9b, and the first reinforcing portion 9a and the second reinforcing portion 9b. The reinforcement part 9b can be made into the structure which has the code | cord bending part X in these boundary parts. The example illustrated in FIG. 3A is an example in which the first reinforcing portion 9a and the second reinforcing portion 9b are adjacent to each other. Moreover, the pneumatic radial tire 1 of this embodiment has the 1st reinforcement layer 91 and the 2nd reinforcement part 9b in which the some reinforcement layers 91 and 92 have the 1st reinforcement part 9a, as shown to FIGS. 3-2. It can also be made into the structure which consists of the 2nd reinforcement layer 92 and the 1st reinforcement layer 91 and the 2nd reinforcement layer 92 were laminated | stacked in part. The example shown in FIG. 3-21 is an example in which the first reinforcing portion 9a and the second reinforcing portion 9b overlap.

  Among the structures of these reinforcing layers 9 (91, 92), the structure of the reinforcing layer 9 shown in FIG. 3A continuously changes the cord angles α, β. For this reason, this example is preferable in that the rigidity of the reinforcing layer 9 can be continuously changed without abruptly changing in the tire radial direction. Therefore, according to the structure of the reinforcing layer 9 shown in FIG. 3A, it is possible to suppress a failure at a place where the cord angles α and β change due to the continuous change in the rigidity of the reinforcing layer 9. Can do.

  On the other hand, the structure of the reinforcing layers 91 and 92 shown in FIG. 3-2 includes a first reinforcing layer 91 having a first reinforcing portion 9a having a cord angle α and a second reinforcing portion 9b having a cord angle β. A reinforcing layer 92 is laminated on a part of these. For this reason, this example is preferable in that the manufacture of the entire reinforcing layer can be simplified. Therefore, according to the structure of the reinforcing layers 91 and 92 shown in FIG. 3-2, the production efficiency of the pneumatic radial tire 1 can be increased.

  Here, in each of FIGS. 3A and 3B, the tire radial direction distance Hu described above (the tire radial direction distance from the center of gravity 51a of the bead core to the cord bending portion X that changes from the cord angle β to the cord angle α). The cord bending portion X used for guiding the above will be described. The cord bending portion X means the first reinforcing portion 9a in the tire radial direction outer side region of the reinforcing layer 9 and the second reinforcing portion 9b in the vicinity of the carcass folded end portion 6a in the tire side view (right view in FIG. 2). And the boundary. As shown in FIG. 3A, in the structure in which the first reinforcing portion 9a and the second reinforcing portion 9b constituting the single reinforcing layer 9 have the cord bent portion X at their boundary, the cord bent portion X is It means the portion of the reinforcing layer 9 at the height position in the tire radial direction where the cord angle is the average angle of the cord angles α and β. Further, as shown in FIG. 3-2, in the structure in which the first reinforcing layer 91 having the first reinforcing portion 9a and the second reinforcing layer 92 having the second reinforcing portion 9b are partially laminated, the cord is bent. The part X means a portion at the midpoint position in the tire radial direction of the overlapping portion of the two reinforcing layers 9.

  FIG. 4 is a diagram illustrating an example of a main part A of the pneumatic radial tire illustrated in FIG. 1 and a cord extending direction of a reinforcing layer. The example shown in FIG. 4 is different from the example shown in FIG. 2 in that a third reinforcing portion 9 c having a cord angle γ is provided in the reinforcing layer 9. In FIG. 4, the left figure is a view as seen from the tire meridional section as in FIG. 1, and the right figure is a view as seen from the side of the tire. Moreover, the left figure and right figure of FIG. 4 respond | correspond in a tire radial direction, and this correspondence is shown with the dotted line.

  4, Hc is a tire radial direction distance from the center of gravity 51a of the bead core to the carcass folding end portion 6a, and Hu is a cord bending portion that changes from the center of gravity 51a of the bead core to the cord angle α from the cord angle β. X is a tire radial direction distance to X, H is a tire radial direction distance from the center of gravity 51a of the bead core to the outermost portion of the reinforcing layer 9 in the tire radial direction, and Hl is from the center of gravity 51a of the bead core to the cord angle γ from the cord angle β. This is the distance in the tire radial direction to the changing cord bending portion Y.

  In the pneumatic radial tire 1 including the main part illustrated in FIG. 4, as in the pneumatic radial tire 1 including the main part illustrated in FIG. 2, in the tire meridian cross-sectional view, on the outer side in the tire width direction of the carcass folded end portion 6 a, The reinforcing layer 9 is formed substantially parallel to the extending direction of the carcass 6 (see the left diagram in FIG. 4). Moreover, in the pneumatic radial tire 1 including the main part illustrated in FIG. 4, the organic fiber cord or the metal cord of the first reinforcing portion 9 a is in the tire circumferential direction, similarly to the pneumatic radial tire 1 including the main part illustrated in FIG. 2. And the cord angle β formed by the organic fiber cord or metal cord of the second reinforcing portion 9b with respect to the tire circumferential direction satisfies α <β (see the right diagram in FIG. 4). For this reason, the pneumatic radial tire 1 including the main part illustrated in FIG. 4 has the carcass folded end portion by the second reinforcing layer 9b of the reinforcing layer 9 in the same manner as the pneumatic radial tire 1 including the main part illustrated in FIG. The first reinforcing layer 9a of the reinforcing layer 9 can reduce the shear strain in the outer region in the tire radial direction while ensuring the rigidity in the tire radial direction in the region near 6a. As a result, the shear strain promoted by the carcass folded end portion 6a due to the shear strain can be reduced. Therefore, according to the pneumatic radial tire 1 having such a configuration, it is possible to suppress failure of the carcass folded end portion 6a and the outer end portion in the tire radial direction of the reinforcing layer 9.

  In the pneumatic radial tire 1 including the main part shown in FIG. 4, the reinforcing layer 9 further has a third reinforcing part 9 c, and the third reinforcing part 9 c is in a region not more than the tire radial distance Hc from the center of gravity 51 a of the bead core. The cord angle γ formed by the organic fiber cord or metal cord of the third reinforcing portion 9c with respect to the tire circumferential direction and the cord angle formed by the organic fiber cord or metal cord of the second reinforcing portion 9b with respect to the tire circumferential direction β satisfies γ <β.

  In the pneumatic radial tire 1 including the main portion shown in FIG. 4, the cord angles γ and β of the reinforcing layer 9 are different between the third reinforcing portion 9c and the second reinforcing portion 9b. That is, in the pneumatic radial tire 1, the cord angle γ formed by the organic fiber cord or the metal cord in the third reinforcing portion 9c with respect to the tire circumferential direction is the organic fiber cord or the metal cord in the second reinforcing portion 9b. It is smaller than the cord angle β formed with respect to the direction. For this reason, while the rigidity in the tire radial direction is secured by the second reinforcing portion 9b, the third reinforcing portion 9c allows the region of the tire core radial distance Hc to be equal to or less than the tire radial direction distance Hc (hereinafter referred to as “tire diameter” if necessary). The rigidity in the tire circumferential direction in the “direction inner region”) can be improved. As a result, it is possible to improve the casing rigidity due to the improvement in the rigidity in the tire circumferential direction. Therefore, the pneumatic radial tire 1 including the main part shown in FIG. 4 improves the casing rigidity due to the improvement of the rigidity in the tire circumferential direction as compared with the pneumatic radial tire 1 including the main part shown in FIG. This is a more preferable example.

  In the pneumatic radial tire 1 including the main part shown in FIG. 4, it is more preferable that the cord angle γ satisfies 0 ° <γ ≦ 30 °. By satisfying 0 ° <γ, rigidity in the tire radial direction in the tire radial direction inner region of the reinforcing layer 9 can be secured. In addition, by satisfying γ ≦ 30 °, it is possible to improve the rigidity in the tire circumferential direction in the tire radial direction inner region of the reinforcing layer 9. As a result, it is possible to improve the casing rigidity due to the improvement in the rigidity in the tire circumferential direction.

  In the pneumatic radial tire 1 including the main part shown in FIG. 4, the outermost portion in the tire radial direction of the third reinforcing portion 9c is a position of 0.2 × Hc or more and 0.8 × H or less from the center of gravity 51a of the bead core. Is more preferable. By setting the outermost portion in the tire radial direction of the third reinforcing portion 9c to a position more than 0.2 times the tire radial direction distance Hc from the center of gravity 51a of the bead core, the third reinforcing portion 9c is sufficiently secured, thereby It becomes possible to further improve the rigidity in the circumferential direction. As a result, the casing rigidity can be further improved due to the improvement in rigidity in the tire circumferential direction. Further, by setting the innermost portion in the tire radial direction of the third reinforcing portion 9c to a position not more than 0.8 times the tire radial direction distance Hc, by sufficiently securing the second reinforcing portion 9b, the carcass folded end portion Sufficient rigidity in the tire radial direction in the vicinity of 6a can be ensured.

  The pneumatic radial tire 1 including the main part shown in FIG. 4 is reinforced at the third reinforcing portion 9c in the tire radial direction inner region of the reinforcing layer 9 and the second reinforcing portion 9b in the region near the carcass folded end portion 6a. Although the cord angles γ and β of the layer 9 are different, the following structure can be adopted as the structure of the reinforcing layer 9.

  That is, in the pneumatic radial tire 1 including the main portion shown in FIG. 4, the single reinforcing layer 9 has the second reinforcing portion 9b and the third reinforcing portion 9c, and the second reinforcing portion 9b and the third reinforcing portion 9c. However, it can be set as the structure (single structure) which has a code | cord | flexion bending part in these boundary parts. That is, the single structure is a structure in which the second reinforcing portion 9b and the third reinforcing portion 9c are adjacent to each other. Further, the pneumatic radial tire 1 including the main part shown in FIG. 4 includes a first reinforcing layer having a first reinforcing part 9a and a second reinforcing layer having a second reinforcing part 9b. A structure in which the reinforcing layer and the second reinforcing layer are partially laminated (composite structure) can also be used. That is, the composite structure is a structure in which the second reinforcing portion 9b and the third reinforcing portion 9c overlap.

  Among these reinforcing layer structures, the single structure described above continuously changes the cord angles γ and β. For this reason, in this example, the rigidity of the reinforcing layer 9 can be continuously changed without abruptly changing in the tire radial direction, and failure at locations where the cord angles γ and β change can be suppressed. Is preferable.

  On the other hand, the composite structure described above includes a second reinforcing layer having a second reinforcing portion 9b having a cord angle β and a third reinforcing layer having a third reinforcing portion 9c having a cord angle γ in a part of these. Laminated. For this reason, this example is preferable in that the manufacturing of the entire reinforcing layer can be simplified and the manufacturing efficiency of the pneumatic radial tire 1 can be increased.

  Here, the cord bending portion Y used for deriving the tire radial direction distance Hl (the tire radial direction distance from the center of gravity 51a of the bead core to the cord bending portion Y changing from the cord angle β to the cord angle γ) will be described. . The cord bent portion Y is a third reinforcing portion 9c in the tire radial direction inner side region of the reinforcing layer 9 and a second reinforcing portion 9b in the region in the vicinity of the carcass folded end portion 6a in the tire side view (right view in FIG. 4). And the boundary. In the case of the single structure described above, the cord bending portion Y means a portion of the reinforcing layer 9 at a height position in the tire radial direction where the cord angle is an average angle of the cord angles γ and β. In the case of the above composite structure, the cord bent portion Y means a portion at the midpoint position in the tire radial direction of the overlapping portion of the two reinforcing layers 9.

  FIG. 5 is a diagram illustrating an example of a main part A of the pneumatic radial tire illustrated in FIG. 1 and a cord extending direction of a reinforcing layer. The example shown in FIG. 5 differs from the example shown in FIG. 2 in that a difference in height is provided at the end position of the organic fiber cord or metal cord of the reinforcing layer 9 on the outer side in the tire radial direction. In FIG. 5, the left figure is a view from a tire meridional section as in FIG. 1, and the right figure is a view from a tire side view. Moreover, the left figure and right figure of FIG. 5 respond | correspond in a tire radial direction, and this correspondence is shown with the dotted line.

  5, Hc is a tire radial direction distance from the center of gravity 51a of the bead core to the carcass folding end portion 6a, and Hu is a cord bending portion that changes from the center of gravity 51a of the bead core to the cord angle α from the cord angle β. The tire radial direction distance to X, and H is the tire radial direction distance from the center of gravity 51a of the bead core to the outermost portion of the reinforcing layer 9 in the tire radial direction.

  In the pneumatic radial tire 1 including the main part illustrated in FIG. 5, as in the pneumatic radial tire 1 including the main part illustrated in FIG. 2, in the tire meridian cross-sectional view, on the outer side in the tire width direction of the carcass folded end portion 6 a, The reinforcing layer 9 is formed substantially parallel to the extending direction of the carcass 6 (see the left diagram in FIG. 5). Further, in the pneumatic radial tire 1 including the main part illustrated in FIG. 5, the organic fiber cord or the metal cord of the first reinforcing portion 9 a is in the tire circumferential direction, similarly to the pneumatic radial tire 1 including the main part illustrated in FIG. 2. And the cord angle β formed by the organic fiber cord or metal cord of the second reinforcing portion 9b with respect to the tire circumferential direction satisfies α <β (see the right diagram in FIG. 5). For this reason, the pneumatic radial tire 1 including the main part shown in FIG. 5 is similar to the pneumatic radial tire 1 including the main part shown in FIG. The first reinforcing layer 9a of the reinforcing layer 9 can reduce the shear strain in the outer region in the tire radial direction while ensuring the rigidity in the tire radial direction in the region near 6a. As a result, the shear strain promoted by the carcass folded end portion 6a due to the shear strain can be reduced. Therefore, according to the pneumatic radial tire 1 having such a configuration, it is possible to suppress failure of the carcass folded end portion 6a and the outer end portion in the tire radial direction of the reinforcing layer 9.

  In the pneumatic radial tire 1 including the main part shown in FIG. 5, the height difference is provided at the terminal position on the outer side in the tire radial direction of the organic fiber cord or the metal cord. That is, in the pneumatic radial tire 1 including the main part shown in FIG. 5, a part of the plurality of cords is not extended to the outermost part in the tire radial direction in the tire radial direction outer region of the reinforcing layer 9. As a result, the cord arrangement density in the outermost portion in the tire radial direction of the outer region in the tire radial direction of the reinforcing layer 9 is made smaller than the cord arrangement density in the other portion in the outer region in the tire radial direction of the reinforcing layer 9. ing. For this reason, it is possible to further reduce the shear strain in the tire radial direction outer region. As a result, the shear strain promoted by the carcass folded end portion 6a due to the shear strain can be further reduced. Therefore, according to the pneumatic radial tire 1 having such a configuration, it is possible to further suppress the failure of the carcass folded end portion 6a and the outer end portion in the tire radial direction of the reinforcing layer 9.

  In the pneumatic radial tire 1 including the main part shown in FIG. 5, an aspect in which a height difference is provided at the end position of the organic fiber cord or the metal cord on the outer side in the tire radial direction, as shown in FIG. Of course, it is possible to adopt any mode such as a mode in which a height difference is provided every two cords or a mode in which a height difference is provided every three cords.

  Pneumatic radial tires according to the present embodiment and conventional examples were produced and evaluated. The embodiment according to the present embodiment is an example.

  FIG. 6 is a chart showing the results of a performance test of a pneumatic radial tire according to an example of the present invention. In the pneumatic radial tire of the configuration shown in FIG. 1 including the main part shown in FIG. 1 including the main part shown in FIG. 1 or the pneumatic radial tire shown in FIG. Various items shown in FIG. 6 (from the cord angle α formed by the cord with respect to the tire circumferential direction in the first reinforcing portion 9a, the cord angle β formed by the cord with respect to the tire circumferential direction at the second reinforcing portion 9b, and the center of gravity 51a of the bead core. From the tire radial direction distance Hu from the cord angle β to the cord bent portion X changing from the cord angle α, the cord angle γ formed by the cord to the tire circumferential direction in the third reinforcing portion 9c, the center of gravity 51a of the bead core from the cord angle β Manufacture of pneumatic radial tires of Conventional Examples 1 and 2 and Examples 1 to 6 satisfying the tire radial direction distance Hl) to the cord bending portion Y that changes to the cord angle γ It was.

  Each of these test tires was mounted on a rim having a rim size of 8.25 × 22.5, a drum test was performed under a low air pressure condition of 80% of the specified air pressure, and a load of 29.42 kN. The distance traveled until the car broke down was indexed. The results are also shown in FIG. The index shows a better result as the value is larger.

  In addition, when a tire failed in the drum test, it was investigated which part of the tire failed. In particular, a failure at the folded end 6a of the carcass 6 shown in FIG. 2 or 4 (carcass end failure) and a failure at the outer end in the tire radial direction of the reinforcing layer 9 shown in FIG. 2 or 4 (reinforcing layer). The presence / absence of the end failure) is also shown in FIG.

  As is clear from FIG. 6, the pneumatic radial tires of Examples 1 to 6 all have a longer mileage until the tire breaks down than the pneumatic radial tires of Conventional Examples 1 and 2, and There was no failure at the end of the reinforcing layer. This is considered to be because the pneumatic radial tires of Examples 1 to 6 satisfy the relationship of α <β.

  When the pneumatic radial tires of Examples 1 to 6 are viewed individually, the pneumatic radial tires of Examples 2 to 6 each have an innermost portion in the tire radial direction of the first reinforcing layer 9a of 0.5 × (Hc + H). Since the position less than the tire radial distance H is satisfied as described above, the travel distance until the tire breaks down is longer than the pneumatic radial tire of the first embodiment. This is because any of the pneumatic radial tires of Examples 2 to 6 can sufficiently ensure the rigidity in the tire radial direction and can reduce the shear strain in the outer region in the tire radial direction. Conceivable.

  In addition, the pneumatic radial tires of Examples 3 to 6 all have a longer running distance until the tire breaks down than the pneumatic radial tire of Example 2. This is presumably because the pneumatic radial tires of Examples 3 to 6 satisfy γ <β, and hence the casing rigidity can be improved due to the improvement in the rigidity in the tire circumferential direction.

  As described above, the pneumatic radial tire of the present invention is useful for suppressing failure of the carcass folded end portion and the tire radial direction outer end portion of the reinforcing layer.

DESCRIPTION OF SYMBOLS 1 Pneumatic radial tire 2 Tread part 21 Tread surface 22 Circumferential groove 23 Rib 3 Shoulder part 4 Side wall part 5 Bead part 51 Bead core 51a Center of gravity of bead core 52 Hard bead filler 53 Soft bead filler 6 Carcass 6a Carcass folding end part 7 Bead protective layer 8 Belt layer 81, 82, 83, 84, 85 Belt 9, 91, 92 Reinforcement layer 9a First reinforcement portion 9b Second reinforcement portion A Essential portion C Tire equatorial plane CL Crown center H Tire diameter of reinforcement layer from center of gravity of bead core Tire radial direction distance to the outermost part in the direction Hc Tire radial direction distance from the center of gravity of the bead core to the carcass folded end Hl Tire radial direction distance from the center of gravity of the bead core to the cord bent part Y changing from the cord angle β to the cord angle γ Cord angle β from the center of gravity of the bead core Luo code angle alpha to change encoding bent portion in the tire radial direction distance X to X, Y code bent portion alpha, beta, code angle formed code γ reinforcement layer with respect to the tire circumferential direction

Claims (8)

A pneumatic radial tire provided with at least one reinforcing layer in which an organic fiber cord or a metal cord is covered with a rubber material on the outer side in the tire width direction of the carcass folded end portion,
A first reinforcing portion that is mounted on a normal rim and is loaded with a normal internal pressure, and the reinforcing layer is located on the outer side in the tire radial direction of the carcass folded end and on the outermost side in the tire radial direction of the reinforcing layer And a second reinforcing portion that is disposed in a region in the vicinity of the carcass folded end portion and has a tire radial direction position including at least the carcass folded end portion, and is the first reinforcing portion and the second reinforcing portion adjacent to each other? Or overlap,
A cord angle α formed by the organic fiber cord or the metal cord of the first reinforcing portion with respect to the tire circumferential direction, and a cord formed by the organic fiber cord or the metal cord of the second reinforcing portion with respect to the tire circumferential direction. A pneumatic radial tire characterized in that the angle β satisfies α <β.   When the tire radial distance from the center of gravity of the bead core to the carcass folding end portion is Hc, and the tire radial distance from the center of gravity of the bead core to the outermost portion of the reinforcing layer in the tire radial direction is H, the tire of the first reinforcing portion 2. The pneumatic radial tire according to claim 1, wherein the radially innermost portion is a position not less than a distance of 0.5 × (H + Hc) and less than a tire radial distance H from the center of gravity of the bead core.   The pneumatic radial tire according to claim 1 or 2, wherein the first reinforcing portion has a width in the tire radial direction of at least 5 mm.   4. The pneumatic radial tire according to claim 1, wherein the second reinforcing portion is disposed in a region of 0.9 × Hc to 1.1 × Hc from the center of gravity of the bead core. 5.   The single said reinforcement layer has the said 1st reinforcement part and the said 2nd reinforcement part, and the said 1st reinforcement part and the said 2nd reinforcement part have a code | cord | flexion bending part in these boundary parts. The pneumatic radial tire according to any one of the above.   A plurality of the reinforcing layers includes a first reinforcing layer having the first reinforcing portion and a second reinforcing layer having the second reinforcing portion, and the first reinforcing layer and the second reinforcing layer are partially laminated. The pneumatic radial tire according to any one of claims 1 to 4.   The reinforcing layer further includes a third reinforcing portion, and the third reinforcing portion is disposed in a region not more than a tire radial direction distance Hc from the center of gravity of the bead core, and the organic fiber cord or the metal cord of the third reinforcing portion. The cord angle γ formed by the tire circumferential direction and the cord angle β formed by the organic fiber cord or the metal cord of the second reinforcing portion with respect to the tire circumferential direction satisfy γ <β. The pneumatic radial tire according to any one of 6.   The pneumatic radial tire according to any one of claims 1 to 7, wherein a height difference is provided at a terminal position of the organic fiber cord or the metal cord on the outer side in the tire radial direction.

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