JP2012017074A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic radial tire that prevents a failure in the vicinity of a carcass folding-back end.SOLUTION: The tire includes at least two organic fiber-reinforced layers, in which an organic fiber cord is covered with a rubber material, outside in a tire width direction of the carcass folding-back end. The tire is mounted to a normal rim in an unloaded condition that a normal internal pressure fills in the tire. The rubber material is located at from a first position on the inside in a tire radial direction further than the carcass folding-back end to a second position on the outside in the tire radial direction further than the carcass folding-back end and between the organic fiber-reinforced layers.

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 in which a rubber material is disposed between organic fiber reinforced layers.

  In a heavy duty radial tire, in order to relieve the distortion at the end of the carcass folded, a method of disposing an organic fiber reinforcing layer on the outer side in the tire width direction of the end is used.

  For example, Patent Document 1 discloses a heavy duty radial tire including an organic fiber cord layer as an organic fiber reinforcing layer. In this heavy-duty radial tire, the organic fiber cord layer extends from the position near the outside in the tire width direction of the bead core so as to extend away from the folded portion toward the position beyond the end of the folded portion outside in the tire width direction. In addition, the organic fiber cord layer has a first bent portion that bends at an acute angle toward the outer side in the tire width direction with respect to the winding direction and the winding direction at the outer side in the tire radial direction from the position near the outer side in the tire width direction of the bead core. In the cross section, the bending angle of the folded portion and the first bent portion with respect to the winding direction is in the range of 15 to 60 °.

Japanese Patent No. 4315473

  Since the pneumatic radial tire disclosed in Patent Document 1 includes the organic fiber reinforcing layer, the bead portion has high rigidity, and therefore, the strain can be dispersed at the carcass folded end portion. However, since the plurality of organic fiber reinforcing layers are arranged so that the cords cross each other, there is a possibility that shear strain may occur between the organic fiber reinforcing layers. Therefore, due to the shear strain generated between the organic fiber reinforced layers, the occurrence of strain is promoted at the carcass folded end portion where the stress is concentrated, and as a result, the carcass folded end portion may become a failure starting point.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a pneumatic radial tire in which a failure in the vicinity of a carcass folded end portion is suppressed.

  In order to solve the above-described problems and achieve the object, the pneumatic radial tire according to the present invention includes at least an organic fiber reinforcing layer in which an organic fiber cord is covered with a rubber material on the outer side in the tire width direction of the carcass folded end portion. 2 layers, mounted on a regular rim and filled with a regular internal pressure, in a no-load state from a first position radially inward of the carcass folded end to a second position radially outward of the carcass folded end. And a rubber material is disposed between the organic fiber reinforcing layers.

  In the pneumatic radial tire according to the present invention, the rubber material is disposed between the organic fiber reinforcing layers on the outer side in the tire width direction of the carcass folded end and from the first position to the second position. It is installed. For this reason, the rubber material disposed in the predetermined region can relieve the shear strain promoted by the carcass folded end due to the shear strain generated between the organic fiber reinforced layers, and thereby the carcass folded end. Faults in the vicinity can be suppressed.

  In the pneumatic radial tire of the present invention, the distance between the organic fiber cords is substantially constant as in the conventional case, at the inner side in the tire radial direction at the first position and at the outer side in the tire radial direction at the second position. Can do. For this reason, according to the pneumatic radial tire of this invention, it can suppress that a bead part rigidity is impaired greatly.

  In the pneumatic radial tire, the distance between the organic fiber cords of the organic fiber reinforcing layers gradually increases from the first position toward the outer side in the tire radial direction, and the second position. It is desirable that it gradually increases as it goes inward in the tire radial direction, and is maximum near the position in the tire radial direction of the carcass folded end.

  In this pneumatic radial tire, as the distance between the organic fiber cords of the organic fiber reinforcement layers goes from the position in the tire radial direction (first position) to the outer side in the tire radial direction from the carcass folded end, Both gradually increase from the position (second position) on the outer side in the tire radial direction to the inner side in the tire radial direction with respect to the carcass folded end, and are maximum near the position in the tire radial direction on the carcass folded end. .

  Therefore, according to this pneumatic radial tire, the thickness of the rubber material in the tire width direction can be effectively increased in the vicinity of the carcass folded end where stress is concentrated and the distortion is promoted. The distortion between the organic fiber reinforced layers in the vicinity of the portion can be suppressed.

  In the pneumatic radial tire, the distance between the organic fiber cords of the organic fiber reinforcement layers in at least one of the first position and the second position is D1, and the organic fiber reinforcement layers are When the maximum distance between the organic fiber cords is D2, it is desirable that 1.2 × D1 ≦ D2 ≦ 3.0 × D1.

  By setting the relationship between D1 and D2 to 1.2 × D1 ≦ D2, it is possible to sufficiently secure the rubber material arrangement region. For this reason, it is possible to sufficiently relieve the shear strain promoted by the carcass folded end due to the shear strain generated between the organic fiber reinforced layers, thereby sufficiently suppressing the failure in the vicinity of the carcass folded end. it can. In addition, by setting the relationship between D1 and D2 to be D2 ≦ 3.0 × D1, the rubber material disposed between the organic fiber reinforced layers does not become too large, and the wrinkle effect is sufficiently exhibited between the organic fiber reinforced layers. Thus, a decrease in bead portion rigidity can be suppressed. As a result, a failure in the vicinity of the carcass folded end due to sufficient relaxation of the shear strain at the carcass folded end can be sufficiently suppressed.

  Further, in this pneumatic radial tire, the distance in the tire radial direction from the center of gravity of the bead core to the carcass folded end is Hc, the distance in the tire radial direction from the center of gravity of the bead core to the first position is H1, and the center of gravity of the bead core. When the tire radial distance from the center of the bead core to the second position is Hu, and the tire radial distance from the center of gravity of the bead core to the upper end of the organic fiber reinforcing layer in the tire radial direction is Hn. It is desirable that 5 × Hc ≦ Hl ≦ 0.9 × Hc and 1.1 × Hc ≦ Hu <Hn.

  By setting the relationship between H1 and Hc to H1 ≦ 0.9 × Hc, a portion where the distance between the organic fiber cords between the organic fiber reinforcing layers is large can be sufficiently secured. For this reason, it is possible to sufficiently relieve the shear strain promoted at the carcass folded end due to the shear strain generated between the organic fiber reinforced layers, and as a result, sufficiently suppress the failure in the vicinity of the carcass folded end. Can do. In addition, by setting the relationship between Hl and Hc to be 0.5 × Hc ≦ Hl, it is possible to reduce the wrinkle effect between the organic fiber reinforcing layers without excessively securing a portion where the distance between the organic fiber cords between the organic fiber reinforcing layers is large. Can be sufficiently exerted to suppress a decrease in bead rigidity. As a result, a failure in the vicinity of the carcass folded end due to sufficient relaxation of the shear strain at the carcass folded end can be sufficiently suppressed.

  Similarly, by setting the relationship between Hu and Hc to 1.1 × Hc ≦ Hu, it is possible to sufficiently secure a portion where the distance between the organic fiber cords between the organic fiber reinforcing layers is large. For this reason, the shear strain promoted by the carcass folded end due to the shear strain generated between the organic fiber reinforced layers can be sufficiently relieved. As a result, a failure in the vicinity of the carcass folded end can be sufficiently suppressed. In addition, by setting the relationship between Hu and Hn to be Hu <Hn, a wrinkle effect can be exhibited between the upper end portion of the organic fiber reinforcing layer and the organic fiber reinforcing layer, and the tire radial direction of the bead portion It can be suppressed that the rigidity in the outer region is greatly impaired.

  Further, in this pneumatic radial tire, the 300% modulus of the rubber material disposed between the first position and the second position and between the organic fiber reinforcing layers is It is desirable that the rubber material used for the organic fiber reinforcing layer has a modulus of 300% or less. By selecting the physical properties of the rubber material depending on the arrangement position as described above, the shear strain promoted at the carcass folded end due to the shear strain generated between the organic fiber reinforced layers can be sufficiently relieved. A failure in the vicinity of the folded end can be sufficiently suppressed.

  The pneumatic radial tire according to the present invention can suppress a failure in the vicinity of the carcass folded end.

FIG. 1 is a meridional cross-sectional view showing a pneumatic radial tire of the present embodiment. FIG. 2A is a meridional sectional view showing an example of the region A shown in FIG. 1 in an enlarged manner. FIG. 2-2 is a meridional sectional view showing an example of the region A shown in FIG. 1 in an enlarged manner. FIG. 2-3 is a meridional sectional view showing an example of the region A shown in FIG. 1 in an enlarged manner. FIG. 3A is a meridional sectional view showing an example of the region B shown in FIG. 2A in an enlarged manner. FIG. 3-2 is a meridional sectional view illustrating an example of the region B illustrated in FIG. FIG. 3C is an enlarged meridional sectional view of an example of the region B illustrated in FIG. FIG. 4 is a meridional cross-sectional view showing an enlarged bead portion of the pneumatic radial tire of the present embodiment. FIG. 5 is a chart showing the results of the performance test of the pneumatic radial tire according to the 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 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 circumferential direction refers to a direction rotating around the tire rotation axis. The tire width direction refers to the direction parallel to the tire rotation axis, the tire width direction outer side refers to the side away from the tire equator plane in the tire width direction, and the tire width direction inner side refers to the tire equatorial plane in the tire width direction. Say the side. The tire equator plane is a plane that is orthogonal to the tire rotation axis and passes through the center of the tire width. The tire equator line is a line along the tire circumferential 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 is configured to be substantially symmetric about the tire equatorial plane C. For this reason, below, only one side centering on the tire equatorial plane C shown in FIG. 1 will be described, and description on the other side will be omitted.

  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 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 an organic fiber reinforcing layer group 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 organic fiber reinforcement layer group 9 includes a first organic fiber reinforcement layer 91 and a second organic fiber reinforcement layer 92 located on the outer side in the tire width direction of the first organic fiber reinforcement layer 91. The organic fiber reinforcement layers 91 and 92 are provided on the outer side in the tire width direction of the folded portion of the carcass 6, and the end portions on the outer side in the tire radial direction of the organic fiber reinforcement layers 91 and 92 are the tire radial direction end portions of the carcass 6. Rather than the outer side in the tire radial direction. The first organic fiber reinforcing layer 91 and the second organic fiber reinforcing layer 92 are cord layers in which an organic fiber cord is covered with a rubber material. The end portion of the second organic fiber reinforcing layer 92 on the outer side in the tire radial direction is located on the outer side in the tire radial direction of the end portion of the first organic fiber reinforcing layer 91 on the outer side in the tire radial direction. The end portion of the second organic fiber reinforcing layer 92 on the inner side in the tire radial direction is located on the outer side in the tire radial direction of the end portion of the first organic fiber reinforcing layer 91 on the inner side in the tire radial direction.

  The organic fiber cords of the first organic fiber reinforcing layer 91 and the second organic fiber reinforcing layer 92 are preferably crossed with each other in order to increase the bead rigidity. However, the 1st organic fiber reinforcement layer 91 and the 2nd organic fiber reinforcement layer 92 in this embodiment are not restricted to such an aspect, and also include the aspect where the organic fiber cord does not cross mutually.

  The pneumatic radial tire 1 configured as described above has a bead portion 5 configured as follows. FIG. 2A is a meridional cross-sectional view illustrating a region A illustrated in FIG. 1 in an enlarged manner. As shown in FIG. 2A, the first organic fiber reinforcing layer 91 and the second organic fiber reinforcing layer 92 are provided with the rubber material 10 between them in the tire width direction outer peripheral region of the folded end portion of the carcass. It is formed to do. Here, the folded end portion of the carcass means a carcass extending to the outermost side in the tire radial direction among one or a plurality of carcasses, and in the example shown in FIG. 2A, the folded end portion of the carcass 6 Means.

  That is, in the example shown in FIG. 2A, the distance between the organic fiber cords between the organic fiber reinforcement layers is 0.5 mm to 1.5 mm at a position on the inner side in the tire radial direction from the folded end portion of the carcass 6. From the first position to the second position where the distance between the organic fiber cords between the organic fiber reinforcing layers is 0.5 mm to 1.5 mm, which is a position on the outer side in the tire radial direction from the folded end of the carcass 6 And the rubber material 10 is disposed between the organic fiber reinforcing layers 91 and 92.

  Here, in determining the first position and the second position, the distance between the organic fiber cords connected the outermost points in the tire width direction of all the cords in the first organic fiber reinforcing layer 91 in the meridional section view. The distance between the curve (curve 1) and the curve (curve 2) connecting the innermost points in the tire width direction of all the cords in the second organic fiber reinforcing layer 92, and the first organic fiber reinforcing layer 91 Let it be defined as the distance from curve 1 to curve 2 along the normal of curve 1 on the particular code in it.

  In the pneumatic radial tire shown in FIG. 2A, the outer side in the tire width direction of the folded end portion of the carcass 6 is from the first position to the second position, and the organic fiber reinforcing layers 91, 92 are connected to each other. Between these, the rubber material 10 is disposed. For this reason, the rubber material 10 disposed in the predetermined region can relieve the shear strain promoted at the folded end portion of the carcass 6 due to the shear strain generated between the organic fiber reinforcing layers 91 and 92. . As a result, failure in the vicinity of the folded end of the carcass 6 can be suppressed.

  Further, according to the pneumatic radial tire including the bead portion illustrated in FIG. 2A, the organic fiber reinforcing layers 91 and 92 are provided on the inner side in the tire radial direction at the first position and on the outer side in the tire radial direction from the second position. The distance between them is almost constant. For this reason, according to the example shown to FIGS. 2-1, it becomes possible to suppress that a bead part rigidity is impaired largely.

  In the example shown in FIG. 2A, the first organic fiber reinforcement layer 91 and the second organic fiber reinforcement layer 92 are defined as described above, and the organic fiber cords included in the organic fiber reinforcement layer 91 (FIG. 2). -1) and the distance between the organic fiber cords included in the organic fiber reinforcing layer 92 (circles in FIG. 2-1) is the position on the inner side in the tire radial direction from the folded end of the carcass 6 (first Gradually increases from the position) toward the outside in the tire radial direction. Further, the distance gradually increases from the position (second position) on the outer side in the tire radial direction from the folded end of the carcass 6 toward the inner side in the tire radial direction. Further, the distance is maximum in the vicinity of the position in the tire radial direction of the folded end portion of the carcass 6.

  That is, in the pneumatic radial tire including the bead portion illustrated in FIG. 2A, as the distance between the organic fiber cords of the organic fiber reinforcing layers 91 and 92 increases from the first position toward the outer side in the tire radial direction, Both gradually increase from the position 2 toward the inner side in the tire radial direction, and are maximum near the position in the tire radial direction of the folded end portion of the carcass 6.

  For this reason, according to the pneumatic radial tire including the bead portion shown in FIG. 2A, the thickness in the tire width direction of the rubber material 10 is efficiently increased in the vicinity of the folded end portion of the carcass 6 where stress is concentrated and distortion is promoted. Can be increased. As a result, distortion between the organic fiber reinforced layers near the carcass folded end can be suppressed.

  As shown in FIG. 2A, the arrangement shape of the rubber material 10 can be a substantially crescent moon shape as viewed from the meridional section, but is not limited to such a shape in the present embodiment. FIG. 2-2 is an enlarged meridional cross-sectional view illustrating an example of the region A illustrated in FIG. 1, and is an example in which the shape of the rubber material 10 is different from that in FIG. 2-1. As shown in FIG. 2B, the shape of the rubber material 10 may be a rectangle in meridional section. In the present embodiment, the shape of the rubber material 10 may be a trapezoid shown in FIG. Among these shapes, the trapezoidal shape shown in FIG. 2-3 is optimal because it can reduce the step difference in manufacturing and suppress manufacturing failures.

  In the pneumatic radial tire 1 shown in FIG. 1, a position (first position) on the inner side in the tire radial direction from the folded end portion of the carcass 6 and a position (first position) on the outer side in the tire radial direction from the folded end portion of the carcass 6. 2), the distance between the organic fiber cords between the organic fiber reinforcement layers 91 and 92 in at least one of them is D1, and the maximum distance between the organic fiber cords between the organic fiber reinforcement layers 91 and 92 is D2. 1.2 × D1 ≦ D2 ≦ 3.0 × D1 is preferable.

  FIG. 3A is a meridional sectional view showing an example of the region B shown in FIG. 2A in an enlarged manner. In the example shown in FIG. 3A, the distance between the organic fiber cords 91a and 92a between the organic fiber reinforcing layers 91 and 92 at a position (second position) on the outer side in the tire radial direction from the folded end portion of the carcass 6 is D1u. In addition, when the maximum distance between the organic fiber cords 91b and 92b, which is the distance between the organic fiber cords 91b and 92b, is D2, 1.2 × D1u ≦ D2 ≦ 3.0 × D1u It has become.

  By setting the relationship between D1u and D2 to be 1.2 × D1u ≦ D2, it is possible to sufficiently secure the arrangement region of the rubber material 10. For this reason, the shear strain promoted at the folded end portion of the carcass 6 due to the shear strain generated between the organic fiber reinforcing layers 91 and 92 can be sufficiently reduced. As a result, it is possible to sufficiently suppress a failure in the vicinity of the folded end of the carcass 6. Further, by setting the relationship between D1u and D2 to be D2 ≦ 3.0 × D1u, the rubber material 10 disposed between the organic fiber reinforcing layers 91 and 92 is not excessively large, and the distance between the organic fiber reinforcing layers 91 and 92 is increased. In this case, the wrinkle effect can be sufficiently exerted to suppress the decrease in the rigidity of the bead portion 5. As a result, it is possible to sufficiently suppress the failure in the vicinity of the folded end portion of the carcass 6 by sufficiently relaxing the shear strain at the folded end portion of the carcass 6.

  In the example shown in FIG. 3A, the distance D1u described above at a position (second position) on the outer side in the tire radial direction from the folded end portion of the carcass 6, and the organic fiber cords 91 b and 92 b in the vicinity of the folded end portion of the carcass 6. Although it is an aspect which prescribed | regulated the relationship with the maximum distance D2 between organic fiber cords which is an inter-distance, this embodiment is not restricted to such an aspect.

  FIGS. 3-2 and 3-3 are meridional cross-sectional views showing an example of the region B shown in FIG. 2-1, and are diagrams showing examples different from the example shown in FIG. 3-1. In the present embodiment, as shown in FIG. 3-2, the bead portion 5 is formed between the organic fiber reinforcing layers 91 and 92 at a position (first position) on the inner side in the tire radial direction from the folded end portion of the carcass 6. When the distance between the organic fiber cords 91c and 92c is D1l and the maximum distance between the organic fiber cords 91b and 92b between the organic fiber reinforcing layers 91 and 92 is D2, the distance between the organic fiber cords 91c and 92c is 1.2. × D1l ≦ D2 ≦ 3.0 × D1l.

  According to the mode shown in FIG. 3-2, since the relationship between D1l and D2 is 1.2 × D1l ≦ D2, it is possible to sufficiently secure the arrangement region of the rubber material 10, and therefore the organic fiber reinforcing layer The shear strain promoted at the folded end portion of the carcass 6 due to the shear strain generated between 91 and 92 can be sufficiently relaxed. As a result, it is possible to sufficiently suppress a failure in the vicinity of the folded end of the carcass 6. In addition, by setting the relationship between D1l and D2 to be D2 ≦ 3.0 × D1l, the rubber material 10 formed between the organic fiber reinforcing layers 91 and 92 is not excessively large, and between the organic fiber reinforcing layers 91 and 92 In addition, it is possible to sufficiently exhibit the wrinkle effect and suppress a decrease in the rigidity of the bead portion 5. As a result, it is possible to sufficiently suppress the failure in the vicinity of the folded end portion of the carcass 6 by sufficiently relaxing the shear strain at the folded end portion of the carcass 6.

  Moreover, in this embodiment, the bead part 5 has the organic fiber reinforcement layers 91 and 92 in the tire radial direction outer side position (2nd position) rather than the folding | turning edge part of the carcass 6, as shown to FIGS. 3-3. When the distance between the organic fiber cords 91a and 92a is D1u and the maximum distance between the organic fiber cords 91b and 92b between the organic fiber cords 91b and 92b is D2, 1.2 × D1u ≦ D2 ≦ 3.0 × D1u, and an organic fiber cord between the organic fiber reinforcing layers 91 and 92 at a position (first position) on the inner side in the tire radial direction from the folded end of the carcass 6 When the distance between 91c and 92c is D1l, and the maximum distance between organic fiber cords 91b and 92b between the organic fiber reinforcement layers 91 and 92 is D2 Alternatively, 1.2 × D1l ≦ D2 ≦ 3.0 × D1l may be satisfied.

  The mode shown in FIG. 3C is a combination of the mode shown in FIG. 3A and the mode shown in FIG. 3B, and the relationship between D1u, D1l, and D2 is 1.2 × D1u ≦ D2, and 1. By setting 2 × D1l ≦ D2, it is possible to sufficiently secure the region where the rubber material 10 is disposed, and therefore, at the folded end portion of the carcass 6 due to the shear strain generated between the organic fiber reinforcing layers 91 and 92. The promoted shear strain can be further reduced. As a result, it is possible to further suppress the failure in the vicinity of the folded end portion of the carcass 6. Moreover, the rubber material 10 formed between the organic fiber reinforcement layers 91 and 92 is enlarged by setting the relationship among D1u, D1l, and D2 to D2 ≦ 3.0 × D1u and D2 ≦ 3.0 × D1l. Without any problem, the heel effect can be further exerted between the organic fiber reinforcing layers 91 and 92 to further suppress the decrease in the rigidity of the bead portion 5. As a result, it is possible to further suppress the failure in the vicinity of the folded end portion of the carcass 6 due to further relaxation of the shear strain at the folded end portion of the carcass 6.

  In the pneumatic radial tire 1 shown in FIG. 1, the distance in the tire radial direction from the center of gravity 51a of the bead core to the folded end of the carcass 6 is Hc, and the inner side in the tire radial direction from the center of gravity 51a of the bead core to the folded end of the carcass 6 The distance in the tire radial direction to the position (first position) is H1, and the distance in the tire radial direction from the center of gravity 51a of the bead core to a position (second position) on the outer side in the tire radial direction from the folded end of the carcass 6 is When Hn is the distance in the tire radial direction from the center of gravity 51a of the bead core to the upper end of the organic fiber reinforcing layer 91 having the lowest height in the tire radial direction, 0.5 × Hc ≦ Hl ≦ 0.9 × Hc And 1.1 × Hc ≦ Hu <Hn.

  By setting the relationship between H1 and Hc to H1 ≦ 0.9 × Hc, it is possible to sufficiently secure a portion where the distance between the organic fiber cords 91 and 92 is large. That is, in the example shown in FIG. 4, a portion having a large distance between the organic fiber cords located in the outer peripheral region in the tire width direction of the folded end portion of the carcass 6 can be sufficiently secured. As a result, the shear strain promoted at the folded end portion of the carcass 6 due to the shear strain generated between the organic fiber reinforcing layers 91 and 92 can be sufficiently relieved, and thereby, in the vicinity of the folded end portion of the carcass 6. Failure can be sufficiently suppressed.

  In addition, by setting the relationship between Hl and Hc to be 0.5 × Hc ≦ Hl, it is possible not to excessively secure a portion where the distance between the organic fiber cords 91 and 92 is large. That is, in the example shown in FIG. 4, it is possible not to excessively secure a portion having a large distance between the organic fiber cords that is located in the outer peripheral region in the tire width direction of the folded end portion of the carcass 6. For this reason, between the organic fiber reinforcement layers 91 and 92, the wrinkle effect can fully be exhibited and the fall of the rigidity of the bead part 5 can be suppressed. As a result, a failure in the vicinity of the folded end of the carcass 6 due to sufficient relaxation of the shear strain at the folded end of the carcass 6 can be sufficiently suppressed.

  Similarly, by setting the relationship between Hu and Hc to 1.1 × Hc ≦ Hu, it is possible to sufficiently secure a portion where the distance between the organic fiber cords 91 and 92 is large. As a result, the shear strain promoted at the folded end portion of the carcass 6 due to the shear strain generated between the organic fiber reinforcing layers 91 and 92 can be sufficiently relieved, and thereby, in the vicinity of the folded end portion of the carcass 6. Failure can be sufficiently suppressed. In addition, when the relationship between Hu and Hn is set to Hu <Hn, the wrinkle effect can be exerted between the upper ends of the organic fiber reinforcing layers 91 and 92 and between the organic fiber reinforcing layers 91 and 92. It can suppress that the rigidity in the tire radial direction outer side area | region of the bead part 5 is impaired greatly.

  In the pneumatic radial tire 1 shown in FIG. 1, a position (first position) on the inner side in the tire radial direction from the folded end portion of the carcass 6 (a second position on the outer side in the tire radial direction from the folded end portion of the carcass 6). The 300% modulus of the rubber material 10 disposed between the organic fiber reinforcing layers 91 and 92 is 300% of the rubber material 10 used for the organic fiber reinforcing layers 91 and 92. It is preferable that it is below the modulus.

  By selecting the physical properties of the rubber material 10 depending on the arrangement position, the shear strain promoted at the folded end portion of the carcass 6 due to the shear strain generated between the organic fiber reinforcing layers 91 and 92 is sufficiently relieved. be able to. As a result, a failure in the vicinity of the folded end of the carcass 6 can be sufficiently suppressed.

  More preferably, the rubber material 10 has a 300% modulus of 10.0 MPa to 12.0 MPa. By setting the 300% modulus of the rubber material 10 to 10.0 MPa or more, the rubber material 10 and the rubber material used for the organic fiber reinforcing layers 91 and 92 are not greatly changed. It is possible to reduce the distortion. Moreover, the distortion suppression effect between the layers of the organic fiber reinforcement layers 91 and 92 can be increased by setting the 300% modulus of the rubber material 10 to 12.0 MPa or less. Incidentally, the rubber material used for the organic fiber reinforcing layers 91 and 92 has a 300% modulus of 12.0 MPa to 14.0 MPa.

  Although the example shown above is an example in which the organic fiber reinforcing layer is two layers, the present embodiment is not limited to such an aspect. That is, when the organic fiber reinforcing layer is n layers (n is a natural number of 3 or more), n-1 rubber material filling regions can be provided between the organic fiber reinforcing layers.

  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.

  In the pneumatic radial tire having the configuration shown in FIG. 1 with the tire size common to 11R22.5, the matters shown in FIG. 5 (the organic fiber cords, which are the distances between the organic fiber cords 91b and 92b shown in FIG. 3A). Distance D2 between the center of gravity 51a of the bead core shown in FIG. 4 and the tire radial direction distance H1 from the turning end of the carcass 6 to the inner position in the tire radial direction (first position). The tire radial direction distance Hu to the position (second position) on the outer side in the tire radial direction from the folded end, and the tire radial direction area from the first position to the second position, and the organic fiber reinforcing layer 91 The pneumatic radial tires of the conventional example and Examples 1 to 7 satisfying the modulus M) of the rubber member 10 disposed in the region sandwiched between the two members 92 were manufactured. Note that D1u in the conventional example indicates D1u in FIG. 3-1, which means that the distance between the organic fiber cords 91a and 92a is constant at D1u from the first position to the second position. .

  Each of these test tires was mounted on a rim having a rim size of 8.25 × 22.5, and 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 tire 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, the presence / absence of failure at the folded end of the carcass 6 and failure between the organic fiber reinforcing layers 91 and 92 shown in FIG.

  As is clear from FIG. 5, the pneumatic radial tires of Examples 1 to 7 all have a longer running distance until the tire breaks down than the pneumatic radial tire of the conventional example. As for this, as for the pneumatic radial tire of Examples 1-7, all are from the 1st position inside a tire radial direction rather than a carcass folding end part to the 2nd position outside a tire radial direction rather than a carcass folding end part. It is considered that the rubber material 10 is disposed between the organic fiber reinforcing layers.

  Looking at the pneumatic radial tires of Examples 1 to 7 individually, the pneumatic radial tires of Examples 5 to 7 all satisfy 1.2 × D1u ≦ D2 ≦ 3.0 × D1u, and 0.5 XHc ≦ Hl ≦ 0.9 × Hc and 1.1 × Hc ≦ Hu <Hn. For this reason, the travel distance until the tire broke down was extremely long, and neither a failure at the folded end of the carcass 6 nor a failure between the organic fiber reinforcing layers 91 and 92 was observed. In addition, about the pneumatic radial tire of Examples 5-7, the failure location at the time of a tire failure was mainly a belt edge.

  Since the pneumatic radial tires of Examples 1 and 2 do not satisfy 1.2 × D1u ≦ D2 ≦ 3.0 × D1u, the traveling until the tire fails compared to the pneumatic radial tires of Examples 5-7. The distance was short, and either a failure at the folded end of the carcass 6 or a failure between the organic fiber reinforcing layers 91 and 92 was observed.

  Since the pneumatic radial tire of Example 3 does not satisfy 0.5 × Hc ≦ Hl ≦ 0.9 × Hc, the travel distance until the tire breaks down as compared with the pneumatic radial tires of Examples 5 to 7 is increased. A short failure was observed at the folded end of the carcass 6. Since the pneumatic radial tire of Example 4 does not satisfy 1.1 × Hc ≦ Hu <Hn, the travel distance until the tire breaks down compared to the pneumatic radial tires of Examples 5 to 7, and A failure at the folded end of the carcass 6 was observed.

  As shown in FIG. 5, in Examples 1 to 7, the modulus M of the rubber material 10 is confirmed to be a problem-free result in any range from 10.0 MPa to 12.0 MPa. It was done.

  As described above, the pneumatic radial tire of the present invention is useful for suppressing failure in the vicinity of the carcass folded end portion.

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 7 Bead protective layer 8 Belt layer 81, 82, 83, 84, 85 Belt 9 Organic fiber reinforcing layer group 91 First organic fiber reinforcing layer 91a, 91b, 91c Organic fiber cord included in first organic fiber reinforcing layer 92 Second organic fiber reinforcing layer 92a, 92b, 92c Organic fiber cord included in second organic fiber reinforcing layer 10 Rubber material A, B Region D1u, D1l, D2 Distance between organic fiber cords between organic fiber reinforcing layers C Tire equatorial plane CL Crown center Hc Carcass folded end from bead core center of gravity Tire radial distance to the part Distance in the tire radial direction from the center of gravity of the bead core to the position (first position) on the inner side in the tire radial direction from the carcass folding end portion Hn From the center of gravity of the bead core to the upper end in the tire radial direction of the organic fiber reinforcing layer having the lowest height Distance in the tire radial direction Distance in the tire radial direction from the center of gravity of the Hu bead core to a position (second position) on the outer side in the tire radial direction from the carcass folded end.

Claims (5)

  The carcass folded end portion is provided with at least two organic fiber reinforcing layers coated with a rubber material on the outer side in the tire width direction of the carcass folded end portion, mounted on a regular rim, and filled with a regular internal pressure in an unloaded state. A rubber material is disposed between the first position on the inner side in the tire radial direction and the second position on the outer side in the tire radial direction with respect to the carcass folded end portion, and between the organic fiber reinforcing layers. A pneumatic radial tire characterized by being provided.   The distance between the organic fiber cords of the organic fiber reinforcing layers gradually increases from the first position toward the outer side in the tire radial direction, and gradually increases from the second position toward the inner side in the tire radial direction. 2. The pneumatic radial tire according to claim 1, wherein the pneumatic radial tire is large and is maximum near a position in a tire radial direction of a carcass folded end portion.   The distance between the organic fiber cords of the organic fiber reinforcement layers in at least one of the first position and the second position is D1, and the maximum distance between the organic fiber cords of the organic fiber reinforcement layers is D2. 3. The pneumatic radial tire according to claim 1, wherein 1.2 × D1 ≦ D2 ≦ 3.0 × D1.   The distance in the tire radial direction from the center of gravity of the bead core to the carcass folded end is Hc, the distance in the tire radial direction from the center of gravity of the bead core to the first position is Hl, and the tire diameter from the center of gravity of the bead core to the second position. When the directional distance is Hu, and the tire radial direction distance from the center of gravity of the bead core to the tire radial direction upper end of the organic fiber reinforcing layer is Hn, 0.5 × Hc ≦ Hl ≦ 0.9 × The pneumatic radial tire according to any one of claims 1 to 3, wherein Hc and 1.1 x Hc ≤ Hu <Hn.   A 300% modulus of a rubber material between the first position and the second position and disposed between the organic fiber reinforcing layers was used for the organic fiber reinforcing layer. The pneumatic radial tire according to any one of claims 1 to 4, which has a modulus of 300% or less of the rubber material.