JP6022841B2 - Pneumatic radial tire - Google Patents

Description

  The present invention relates to a highly durable pneumatic radial tire characterized by the structure of the bead portion, and is particularly useful as a heavy-duty pneumatic radial tire.

  Conventionally, pneumatic radial tires used for heavy vehicles such as industrial vehicles and construction vehicles have a concern of causing problems such as separation starting from the winding end of the carcass ply wound around the bead core. . On the other hand, as described in Patent Documents 1 to 3, a technique is known in which a protective layer is disposed along the outside of the carcass ply of the bead portion to improve the durability of the bead portion. However, depending on the country or region, it may be used at a very high internal pressure, and it is necessary to further improve the durability of the bead portion.

  In order to suppress a failure at the winding end of the carcass ply, a steel protective layer including a steel cord as disclosed in Patent Document 1 is suitable. Further, the inventor has found that the strain acting on the winding end of the carcass ply can be effectively reduced by arranging the inner end of the steel protective layer located at the inner side in the tire width direction at a predetermined height. It has gained. However, on the other hand, it has been found that there is a possibility of failure starting from the inner edge of the steel protective layer, and there is room for improvement.

  The failure starting from the inner end of the steel protective layer as described above cannot be distinguished from the appearance of the tire mounted on the rim, so it is almost impossible to find it during use. If the inner surface of the tire is damaged due to this failure, the air inside the tire may reach the carcass ply and cause rust, etc., leading to quality deterioration. Therefore, it is desirable to take sufficient measures not only for the rolled-up end of the carcass ply but also for the failure at the inner end of the steel protective layer and the outer end of the steel protective layer located on the outer side in the tire width direction.

JP 63-110006 A JP 59-109406 A JP 7-137507 A

  The present invention has been made in view of the above circumstances, and its purpose is to suppress not only the rolled-up end of the carcass ply but also the failure of the end of the steel protective layer, and the air having excellent durability of the bead portion. The purpose is to provide a radial tire.

  The above object can be achieved by the present invention as described below. That is, a pneumatic radial tire according to the present invention includes a pair of bead portions, a sidewall portion extending outward in the tire radial direction from each of the bead portions, and a tread that is continuous with the tire radial outer end of each of the sidewall portions. A bead core embedded in the bead portion, and a carcass ply wound from the tread portion through the sidewall portion to the bead portion and wound around the bead core from the inner side to the outer side in the tire width direction. In a pneumatic radial tire, a steel protective layer that includes a steel cord, is disposed along the outside of the carcass ply of the bead portion, and is wound around the bead core from the inside to the outside in the tire width direction, and an organic fiber Including a cord, disposed along an outer side of the steel protective layer of the bead portion, An organic fiber protective layer wound up from the inner side in the tire width direction around the outer side of the tire, and the outer end of the steel protective layer located on the outer side in the tire width direction is a tire diameter than the rolled-up end of the carcass ply. An inner end of the steel protective layer located on the outer side in the tire width direction and located on the inner side in the tire width direction is disposed on the outer side in the tire radial direction from the upper end of the bead core to the outer side in the tire radial direction from the point of 20 mm. The outer end of the organic fiber protective layer positioned is disposed on the outer side in the tire radial direction from the outer end of the steel protective layer, and the inner end of the organic fiber protective layer positioned on the inner side in the tire width direction is the steel protective layer. It is arrange | positioned rather than the inner side end of a tire radial direction.

  In this tire, the outer end of the steel protective layer is disposed on the outer side in the tire radial direction from the rolled-up end of the carcass ply, and the inner end of the steel protective layer is located on the outer side in the tire radial direction from the upper end of the bead core more than 20 mm. Since it is arranged on the outer side in the tire radial direction, it is possible to effectively reduce the distortion acting on the winding end of the carcass ply. Nevertheless, since the outer end of the organic fiber protective layer is disposed on the outer side in the tire radial direction than the outer end of the steel protective layer, it is possible to favorably suppress the occurrence of a failure starting from the outer end of the steel protective layer.

  The strain acting on the winding end of the carcass ply is due to the tension acting on the carcass cord included in the carcass ply, and the tension tends to increase as the internal pressure of the tire increases. The inventor has found that the tension increases in a region of 20 mm from the upper end of the bead core to the outside in the tire radial direction. Therefore, by disposing the steel protective layer so as to cover the carcass ply in this region, it is possible to reduce the strain acting on the winding end of the carcass ply by applying the tension to the steel cord.

  In this tire, since the inner end of the steel protective layer is arranged as described above, there is a concern about failure at the inner end, but the inner end of the organic fiber protective layer is more in the tire radial direction than the inner end of the steel protective layer. By being arranged on the outside, a failure starting from the inner end of the steel protective layer can be suppressed. The inner and outer ends of the organic fiber protective layer are arranged on the outer side in the tire radial direction than the inner and outer ends of the steel protective layer, respectively, but the organic fiber cord is more flexible than the steel cord and the organic fiber protective layer Since the distortion acting on the edge is relatively small, there is little risk of failure.

  In the pneumatic radial tire of the present invention, it is preferable that the inner end of the steel protective layer is disposed at a height not more than 0.35 times the tire cross-section height with respect to the nominal rim diameter. Thereby, in the inner end of the steel protective layer, it is possible to prevent the dynamic strain due to a high load from becoming excessively large, and it is possible to favorably suppress early failure at the inner end of the steel protective layer. The nominal rim diameter is a rim diameter defined by JATMA standards.

  In the pneumatic radial tire of the present invention, it is preferable that the inner end of the organic fiber protective layer is disposed at a height of 0.45 times or less of the tire cross-section height on the basis of the nominal rim diameter. Thereby, it is possible to prevent excessive dynamic strain due to a high load at the inner end of the organic fiber protective layer, and to favorably suppress early failure at the inner end of the organic fiber protective layer.

  In the pneumatic radial tire of the present invention, it is preferable that the organic fiber protective layer is composed of at least two layers. According to such a configuration, failure at the inner end and the outer end of the steel protective layer can be effectively suppressed.

Tire meridian cross-sectional view showing an example of the pneumatic radial tire of the present invention Sectional drawing which expands and shows the bead part of the tire of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. A tire T shown in FIG. 1 is an example of a pneumatic radial tire according to the present invention, and shows a tire meridian cross section when a standard rim is mounted. When a standard rim is mounted, the tire is mounted on a rim specified by JATMA corresponding to the tire size and filled with air with an air pressure of 50 kPa. FIG. 2 is an enlarged sectional view showing the bead portion 1 of the tire T. As shown in FIG.

  The tire T is embedded in the bead portion 1, a pair of bead portions 1, a sidewall portion 2 extending from the bead portion 1 to the outer side in the tire radial direction, a tread portion 3 connected to an outer end in the tire radial direction of the sidewall portion 2, and the bead portion 1. And a carcass ply 4 wound from the tread portion 3 through the sidewall portion 2 to the bead portion 1 and wound around the bead core 1a from the inner side to the outer side in the tire width direction.

  The bead core 1a is composed of a converging body obtained by laminating and winding wires covered with rubber, and is formed in an annular shape along the tire circumferential direction. A rubber filler 1b is arranged outside the bead core 1a in the tire radial direction. The rubber filler 1b has a shape that tapers toward the outer side in the tire radial direction, and the tip thereof is disposed on the outer side in the tire radial direction than the winding end 4E of the carcass ply 4.

  The carcass ply 4 is provided with a series of winding portions 42 arranged on the outer side in the tire width direction of the bead core 1a and the rubber filler 1b on the main body portion 41 extending from the tread portion 3 through the sidewall portion 2 to the bead portion 1. The winding end 4E is an end portion of the winding portion 42. The carcass ply 4 is formed by covering a plurality of carcass cords arranged in a direction substantially orthogonal to the tire circumferential direction with rubber. As the material for the carcass cord, metals such as steel and organic fibers such as polyester, rayon, nylon, and aramid are preferably used.

  In the present embodiment, an example of a tire with a tube in which the tube 5 is built is shown. However, the pneumatic radial tire of the present invention may be a tubeless tire that does not contain a tube. In the case of a tubeless tire, the inner surface of the tire T is configured by an inner liner rubber that prevents permeation of the gas filled in the tire.

  The tire T has a steel protective layer 6 including a steel cord. The steel protective layer 6 is disposed along the outside of the carcass ply 4 of the bead portion 1 and is wound up from the inner side to the outer side in the tire width direction around the bead core 1a. In other words, the steel protective layer 6 includes a series of outer portions 62 positioned on the outer side in the tire width direction of the winding portion 42 on the inner portion 61 positioned on the inner side in the tire width direction of the main body portion 41. The inner end 61E is an end portion of the steel protective layer 6 (inner portion 61) located on the inner side in the tire width direction, and the outer end 62E is an end of the steel protective layer 6 (outer portion 62) located on the outer side in the tire width direction. Part.

  The steel protective layer 6 is formed by covering a plurality of steel cords arranged in a direction inclined with respect to the tire radial direction with rubber. The plurality of steel cords are arranged in parallel to each other, and the inclination angle with respect to the tire radial direction is set to, for example, 50 to 80 °. The steel protective layer 6 is in contact with the carcass ply 4 from the outside so as to wrap the carcass ply 4. The number of ends of the steel cord (the number of cords per inch in the cord width direction) is preferably 10 cords / inch or more, and the cord diameter of the steel cord is preferably 0.9 mm or more.

  Further, the tire T has an organic fiber protective layer 7 containing an organic fiber cord. The organic fiber protective layer 7 is disposed along the outside of the steel protective layer 6 of the bead portion 1 and is wound up from the inner side to the outer side in the tire width direction around the bead core 1a. In other words, the organic fiber protective layer 7 has a series of outer portions 72 positioned on the outer side in the tire width direction of the outer portion 62 on the inner portion 71 positioned on the inner side in the tire width direction of the inner portion 61. The inner end 71E is an end portion of the organic fiber protective layer 7 (inner portion 71) located on the inner side in the tire width direction, and the outer end 72E is an organic fiber protective layer 7 (outer portion 72) located on the outer side in the tire width direction. Is the end of

  The organic fiber protective layer 7 is formed by covering a plurality of organic fiber cords arranged in a direction inclined with respect to the tire radial direction with rubber. The plurality of organic fiber cords are arranged in parallel to each other, and the inclination angle with respect to the tire radial direction is set to 30 to 60 °, for example. Examples of the material for the organic fiber cord include nylon, polyester, rayon, and aramid. The organic fiber protective layer 7 is in contact with the steel protective layer 6 from the outside so as to wrap the steel protective layer 6. The number of ends of the organic fiber cord is preferably 15 / inch or more, and the cord diameter of the organic fiber cord is preferably 0.4 mm or more.

  The outer end 62E of the steel protective layer 6 is disposed on the outer side in the tire radial direction from the winding end 4E of the carcass ply 4. The inner end 61E of the steel protective layer 6 is a point 20 mm outward from the upper end of the bead core 1a in the tire radial direction. It is arranged on the outer side in the tire radial direction than P. Further, the outer end 72E of the organic fiber protective layer 7 is disposed on the outer side in the tire radial direction from the outer end 62E of the steel protective layer 6, and the inner end 71E of the organic fiber protective layer 7 is an inner end 61E of the steel protective layer 6. It arrange | positions rather than the tire radial direction.

  With the steel protective layer 6 having the end portions arranged as described above, it is possible to suppress failures such as separation starting from the winding end 4E of the carcass ply 4. Furthermore, the organic fiber protective layer 7 with the end portions arranged as described above can suppress failures such as separation starting from the end portions of the steel protective layer 6. In particular, in the region X from the upper end of the bead core 1a to the point P, the tension acting on the carcass cord is relatively high. Therefore, by arranging the steel protective layer 6 so as to cover the carcass ply 4 in this region X, the tension can be reduced. Can be borne by a steel cord, and distortion acting on the winding end 4E can be reduced.

  The inner end 61E of the steel protective layer 6 is preferably disposed at a height not more than 0.35 times the tire cross-section height TH with reference to the nominal rim diameter ND. That is, the height HBi of the inner end 61E is preferably 35% or less of the tire cross-section height TH, and more preferably less than 35%. Moreover, in order to suppress the failure at the winding end 4E better, the tire radial direction distance L1 from the point P to the inner end 61E is preferably 20 mm or more.

  The inner end 71E of the organic fiber protective layer 7 is preferably disposed at a height not more than 0.45 times the tire cross-section height TH with reference to the nominal rim diameter ND. That is, the height HCi of the inner end 71E is preferably 45% or less of the tire cross-section height TH, and more preferably less than 45%. Further, in order to better suppress the failure at the inner end 61E, the tire radial direction distance L2 from the inner end 61E to the inner end 71E is preferably 10 mm or more.

  The winding end 4E of the carcass ply 4 is preferably disposed at a height of 0.15 times or more of the tire cross-section height TH with reference to the nominal rim diameter ND. That is, the height HAo of the winding end 4E is preferably 15% or more of the tire cross-sectional height TH. This proportion is more preferably more than 15%.

  The outer end 62E of the steel protective layer 6 is preferably disposed at a height not more than 0.35 times the tire cross-section height TH with reference to the nominal rim diameter ND. That is, the height HBo of the outer end 62E is preferably 35% or less of the tire cross-section height TH, and more preferably less than 35%. Thereby, it is possible to prevent the dynamic strain due to the high load from becoming excessively large at the outer end 62E, and it is possible to satisfactorily suppress early failure at the outer end 62E. Moreover, in order to suppress the failure at the winding end 4E better, the tire radial direction distance L3 from the winding end 4E to the outer end 62E is preferably 10 mm or more.

  The outer end 72E of the organic fiber protective layer 7 is preferably disposed at a height of 0.45 times or less of the tire cross-section height TH with reference to the nominal rim diameter ND. That is, the height HCo of the outer end 72E is preferably 45% or less of the tire cross-section height TH, and more preferably less than 45%. Thereby, it is possible to prevent the dynamic distortion due to the high load from becoming excessively large at the outer end 72E, and it is possible to satisfactorily suppress early failure at the outer end 72E. Further, in order to better suppress the failure at the outer end 62E, the tire radial direction distance L4 from the outer end 62E to the outer end 72E is preferably 10 mm or more.

  The organic fiber protective layer is preferably composed of at least two layers, and the organic fiber protective layer 7 of this embodiment is a two-layered structure in which organic fiber cords with respect to the tire radial direction are inclined in opposite directions. It is configured. The above-described positional relationship of the end portions of the organic fiber protective layer may be satisfied by at least one layer among the plurality of layers constituting the organic fiber protective layer, but is satisfied by all layers as in the present embodiment. It is preferable that

  In the present embodiment, the cover member 8 is attached in a U shape to the outer end 62E of the steel protective layer 6 so as to suppress the occurrence of failure starting from the outer end 62E, particularly the occurrence and progress of separation. . The cover member 8 is made of an organic fiber cord such as a nylon cord.

  The pneumatic radial tire of the present invention is the same as a normal pneumatic tire except that the bead portion is configured as described above, and any conventionally known material, shape, structure, manufacturing method, etc. are adopted in the present invention. be able to. Although the above bead structure should just be applied to the bead part of one side at least, it is preferable to apply to the bead part of both sides.

  The pneumatic radial tire according to the present invention is useful as a heavy-duty pneumatic radial tire that is used in heavy vehicles such as trucks, buses, industrial vehicles, and construction vehicles because the durability of the bead portion is excellent.

  In order to show the configuration and effects of the present invention specifically, a durability test of the bead portion was performed, which will be described below. The size of the tire used for the test was 11.00R20, and was mounted on a 8.00V rim. The tire cross-sectional height of this tire is 287 mm, and the distance in the tire radial direction from the nominal rim diameter to the upper end of the bead core is 26 mm.

  In the durability test, tires were run on a drum having a diameter of 1700 mm on a drum having a diameter of 1700 mm under conditions of an internal pressure of 830 kPa, a load of 3350 kgf (increase by 10% every 24 hours), and a speed of 25 km / h. And it evaluated by the index | exponent when the result of the comparative example 1 was set to 100 with respect to the travel distance. In addition, the tire after the test run was checked for the presence or absence of cracks (separation developed) at the inner end of the steel protective layer and the inner end of the organic fiber protective layer.

  Table 1 shows the bead structure and evaluation results of each example. In Comparative Example 1, the steel protective layer is not provided, but other structures are common. The carcass cord has a wire structure of 3 + 9 + 15 × 0.175 and an end number of 15 / inch. The steel cord has a wire structure of 3 + 9 + 15 × 0.175, an end number of 14 / inch, and an inclination angle of 60 ° with respect to the tire radial direction. The organic fiber protective layer includes nylon cord as an organic fiber cord, the number of ends is 18 / inch, the cord diameter is 0.6 mm, and the inclination angle with respect to the tire radial direction is 50 °.

  As shown in Table 1, in Comparative Examples 3 and 4, although the traveling distance until failure occurred was longer than that in Comparative Examples 1 and 2, cracks were confirmed on the inner surface of the tire. On the other hand, in Examples 1 and 2, the travel distance until failure occurred was longer than that in Comparative Examples 1 and 2, and cracks were not confirmed on the inner surface of the tire. From the above, it can be said that Examples 1 and 2 are superior in durability of the bead portion as compared with Comparative Examples 1 to 4.

DESCRIPTION OF SYMBOLS 1 Bead part 1a Bead core 2 Side wall part 3 Tread part 4 Carcass ply 4E Winding end 6 Steel protective layer 7 Organic fiber protective layer 61E Steel protective layer inner side edge 62E Steel protective layer outer side edge 71E Organic fiber protective layer inner side edge 72E Outside edge of organic fiber protective layer

Claims (3)

A pair of bead portions; a sidewall portion extending outward in the tire radial direction from each of the bead portions; a tread portion connected to an outer end in the tire radial direction of each of the sidewall portions; and a bead core embedded in the bead portion; In a pneumatic radial tire including a carcass ply that extends from the inner side in the tire width direction around the bead core to the bead part through the sidewall part from the tread part,
A steel protective layer including a steel cord, disposed along the outside of the carcass ply of the bead portion, and wound around the bead core from the inside to the outside in the tire width direction;
An organic fiber cord, comprising an organic fiber protective layer disposed along the outside of the steel protective layer of the bead portion, and wound around the bead core from the inside in the tire width direction to the outside;
The outer end of the steel protective layer located on the outer side in the tire width direction is disposed on the outer side in the tire radial direction from the winding end of the carcass ply, and the inner end of the steel protective layer located on the inner side in the tire width direction is the bead core. It is arranged on the outer side in the tire radial direction than the point of 20 mm on the outer side in the tire radial direction from the upper end of
The outer end of the organic fiber protective layer located on the outer side in the tire width direction is disposed on the outer side in the tire radial direction than the outer end of the steel protective layer, and the inner end of the organic fiber protective layer located on the inner side in the tire width direction is , Is disposed on the outer side in the tire radial direction than the inner end of the steel protective layer,
A pneumatic radial tire characterized in that an inner end of the steel protective layer is disposed at a height of 0.35 times or less of a tire cross-section height with respect to a nominal rim diameter. A pair of bead portions; a sidewall portion extending outward in the tire radial direction from each of the bead portions; a tread portion connected to an outer end in the tire radial direction of each of the sidewall portions; and a bead core embedded in the bead portion; In a pneumatic radial tire including a carcass ply that extends from the inner side in the tire width direction around the bead core to the bead part through the sidewall part from the tread part,
A steel protective layer including a steel cord, disposed along the outside of the carcass ply of the bead portion, and wound around the bead core from the inside to the outside in the tire width direction;
An organic fiber cord, comprising an organic fiber protective layer disposed along the outside of the steel protective layer of the bead portion, and wound around the bead core from the inside in the tire width direction to the outside;
The outer end of the steel protective layer located on the outer side in the tire width direction is disposed on the outer side in the tire radial direction from the winding end of the carcass ply, and the inner end of the steel protective layer located on the inner side in the tire width direction is the bead core. It is arranged on the outer side in the tire radial direction than the point of 20 mm on the outer side in the tire radial direction from the upper end of
The outer end of the organic fiber protective layer located on the outer side in the tire width direction is disposed on the outer side in the tire radial direction than the outer end of the steel protective layer, and the inner end of the organic fiber protective layer located on the inner side in the tire width direction is , Is disposed on the outer side in the tire radial direction than the inner end of the steel protective layer,
A pneumatic radial tire characterized in that an inner end of the organic fiber protective layer is disposed at a height of 0.45 times or less of a tire cross-section height on the basis of a nominal rim diameter. The pneumatic radial tire according to claim 1 or 2 , wherein the organic fiber protective layer is composed of at least two layers.

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