JP2009227231A - Run flat tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a run flat tire superior in bead durability. <P>SOLUTION: The run flat tire is equipped with: a pair of bead sections 1 having an annular first bead 1a; side wall sections 2 extending respectively from the bead sections 1 outward in the direction of the radius of the tire; a carcass layer 4 suspended between the bead sections 1 and formed of a carcass ply 14 wound up outward in the tire width direction at the first bead 1a; an annular bulge section 10 swollen outward in the tire width direction from at least one bead section 1, having an inner circumference surface along the outer circumference side curved plane of a rim flange 8a; and an annular second bead 1b made of a pair of opposite bead cores facing each other in the direction of the radius of the tire, while being disposed at the annular bulge section 10, wherein the carcass ply 14 wound up has an outer side end portion in the direction of the width of the tire, locked between the pair of the opposite bead cores. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is arranged in a pair of bead portions having an annular first bead, a sidewall portion, an annular bulge portion bulged outward in the tire width direction of the bead portion, and the annular bulge portion. The present invention relates to a run flat tire including a second bead and having improved bead durability.

  FIG. 3 is a half sectional view showing an example of a conventional run-flat tire. Such a run-flat tire is a so-called side-reinforcement type run-flat tire provided with a reinforcing rubber layer 109 in the sidewall portion 102. When the air pressure inside the tire is reduced due to a failure such as puncture, the reinforcing rubber layer 109 is provided. Prevents the tire from being flattened completely. As a result, run-flat traveling is possible, and a certain distance can be safely traveled.

  The run flat tire includes a pair of bead portions 101, a bead 101a disposed in the bead portion 101, a bead filler 112 disposed on the tire outer periphery side of the bead 101a, and a tire width direction of the bead portion 101. This is a so-called double bead type run-flat tire provided with an annular bulging portion 110 bulging outward and a bead 101b disposed in the annular bulging portion 110. Further, the carcass layer is formed of a carcass ply 104, wound up outward in the tire width direction by a bead portion 101a, and a rolled-up end portion 105 of the carcass ply 104 is disposed so as to sandwich a bead filler 112. In such a run-flat tire, the annular bulging portion 110 holds the rim flange 108a, thereby preventing the rim from coming off. Such a run-flat tire is disclosed, for example, in Patent Documents 1 and 2 below.

However, in the conventional double bead type run-flat tire, when the sidewall portion 102 is bent due to a longitudinal high load during traveling (a high load in the tire radial direction), a large shear strain is applied to the winding end portion 105 of the carcass ply 104. Will occur. As a result, a separation failure may occur in the vicinity of the winding end portion 105, and the bead durability may not be sufficient.
JP 51-116507 A JP-A-53-138106

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pair of bead portions having a first annular bead, a sidewall portion, and an annular bulge that bulges outward in the tire width direction of the bead portion. An object of the present invention is to provide a run-flat tire having a protruding portion and a second bead disposed on the annular bulging portion and having excellent bead durability.

  The above object can be achieved by the present invention as described below. That is, the run-flat tire according to the present invention spans between a pair of bead portions having an annular first bead, sidewall portions extending outward in the tire radial direction from the bead portions, and the bead portions, A carcass layer formed of a carcass ply wound up on the outer side in the tire width direction by the first bead, and an inner peripheral surface that bulges outward in the tire width direction from at least one of the bead parts, and extends along the outer peripheral curved surface of the rim flange. An annular bulging portion, and an annular second bead comprising a pair of opposed bead cores disposed in the annular bulging portion and opposed in the tire radial direction, and the rolled up carcass ply is a pair of the opposed It has the tire width direction outer side edge part stopped between bead cores, It is characterized by the above-mentioned.

  Since the run-flat tire of the present invention is configured to lock the outer end portion in the tire width direction of the rolled carcass ply between a pair of opposed bead cores (second beads) opposed in the tire radial direction, the second bead A sufficient amount of rubber (rubber thickness) between the rim flange and the rim flange can be secured. Thereby, even when a longitudinally high load is applied to the bead portion during traveling, interference between the rim and the second bead can be suppressed, and distortion can be prevented from concentrating on the carcass ply. In the run-flat tire of the present invention, the ends of the rolled-up carcass ply are locked while being sandwiched between a pair of opposed bead cores facing in the tire radial direction, so that they are locked between the bead cores facing in the tire width direction. Compared to the above, the pressing force between the bead cores when a longitudinally high load is applied is high. As a result, it is possible to effectively prevent the carcass ply from being pulled out. In addition, separation failure that occurs near the end of the carcass ply can be prevented by engaging the end of the carcass ply with the pair of opposed bead cores. As mentioned above, according to the run flat tire concerning the present invention, bead durability can be improved.

  In the above, further comprising a winding member that is disposed so that one end is wound from the tire inner peripheral side and the other end is locked between the pair of opposed bead cores. preferable. According to the run-flat tire having such a configuration, the outer end in the tire width direction of the winding member is locked between the pair of opposed bead cores (second beads) opposed in the tire radial direction. A sufficient amount of rubber (rubber thickness) between the rim flange and the rim flange can be secured. As a result, even when a longitudinally high load is applied to the bead portion during traveling, the interference between the rim and the second bead is suppressed, and strain is concentrated on the carcass ply and the winding member, while the first bead-second The space between the beads can be reinforced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a half sectional view showing an example of a run-flat tire according to the present invention.

  The run flat tire shown in FIG. 1 includes a pair of bead portions 1, a sidewall portion 2 extending from the bead portion 1 outward in the tire radial direction, and a tread portion 3 provided between the sidewall portions 2. The pair of bead portions 1 includes a first bead 1a in which a steel wire converging body forms an annular shape in the tire circumferential direction, a bead filler 12 disposed on a tire outer periphery of the first bead 1a, and a tire width of the bead filler 12. The steel side ply 16 is disposed along the outer side surface in the direction, and the tire is configured to be fixed to the rim 8 by being disposed on the tire outer peripheral side of the bead seat portion 8b of the rim 8. . The carcass layer 4 includes a carcass ply 14 in which polyester cords are arranged at an angle of about 90 ° with respect to the tire equator line C, and is disposed so as to be bridged between the pair of bead portions 1. The carcass ply 14 is wound up outward in the tire width direction by the first bead 1a.

  An inner liner layer 5 for maintaining air pressure is disposed on the inner peripheral side of the carcass layer 4, and a belt layer 6 and a belt reinforcement for reinforcing the carcass layer 4 on the outer peripheral side by the effect of warp Layer 7 is disposed. The belt layer 6 is composed of two belt plies in which steel cords are arranged at an angle of about 25 ° with respect to the tire equator line C, and is laminated so that the steel cords cross each other in opposite directions between the belt plies. . As the cord constituting the carcass ply or the belt ply, organic fibers such as rayon, nylon and aramid are used in addition to the above. Usually, these cords are subjected to surface treatment, adhesion treatment or the like in order to improve adhesion to rubber.

  On the inner side of the carcass layer 4 of the sidewall portion 2, a reinforcing rubber layer 9 having a substantially crescent shape in a sectional view of the tire meridian is disposed. As a result, when the air pressure inside the tire decreases, the deformation of the tire is suppressed, and run-flat traveling is possible. The reinforcing rubber layer 9 is composed of, for example, a rubber layer having a hardness of 65 to 90 ° according to a durometer hardness test (A type) of JIS K6253. The reinforcing rubber layer 9 included in the run-flat tire of the present invention can be applied to any reinforcing rubber layer used in a conventional side-reinforcing type run-flat tire without being particularly limited in terms of hardness and thickness. Can do. The reinforcing rubber layer 9 is not limited to a single rubber layer, and may be composed of a plurality of rubber layers having different physical properties such as hardness.

  An annular bulging portion 10 is formed on the outer side of the bead portion 1 in the tire width direction. The annular bulging portion 10 bulges outward in the tire width direction from the rim flange 8a, and has an inner circumferential surface along the outer circumferential curved surface of the rim flange 8a. The pointed head 11 located on the distal end side of the inner peripheral surface is set to have a smaller diameter than the outer diameter of the rim flange 8a, and the annular bulging portion 10 is formed so as to be able to hold the rim flange 8a. Yes. The annular bulging portion 10 is preferably formed on each of the bead portions 1 on both sides. However, the annular bulging portion 10 only needs to be formed on at least one of the bead portions 1, and is formed only on the side that is on the vehicle outer side, for example. It doesn't matter.

  The annular bulging portion 10 is provided with an annular second bead 1b composed of a pair of opposed bead cores facing each other in the tire radial direction. The second bead 1b of the present embodiment is configured by arranging two steel wires having a cross-sectional rectangle in an annular shape while facing each other in the tire radial direction. You may comprise by arrange | positioning cyclically | annularly, bundling so that it may become. Further, the pair of bead cores constituting the second bead 1b is not limited to those made of steel wire, and may be made of, for example, a convergent body of organic fibers or a rubber bead made of fiber reinforced rubber. The second beads 1b are preferably disposed on the annular bulging portions 10 on both sides, but may be formed on at least one of the annular bulging portions 10, for example, on the side that becomes the vehicle outer side when mounted. It may be formed only.

  In the run flat tire according to the present invention, the carcass ply 14 wound up on the outer side in the tire width direction by the first bead 1a is locked between a pair of opposed bead cores constituting the annular second bead 1b. Characterized by having an outer end. In this way, the end of the carcass ply 14 extending outward in the tire width direction (lateral direction) is locked between the pair of opposed bead cores facing in the tire radial direction (longitudinal direction), so Even when a longitudinally high load is applied, the carcass ply 14 can be effectively prevented from being pulled out. Further, since the rubber amount (rubber thickness) between the second bead 1b and the rim flange 8a can be sufficiently secured, the rim 8 and the second bead 1b Interference can be suppressed, and the concentration of strain on the carcass ply 14 can be suppressed. In addition, separation failure that occurs in the vicinity of the end portion of the carcass ply 14 can be prevented by engaging the end portion of the carcass ply 14 while being sandwiched between the pair of opposed bead cores.

[Other Embodiments]
In the above-described embodiment, the example in which only the outer end portion in the tire width direction of the carcass ply is locked between the pair of opposed bead cores constituting the annular second bead is shown, but the present invention is not limited thereto, As shown in FIG. 2, one end is disposed so as to wind the first bead 1a from the tire inner peripheral side, and the other end is locked between a pair of opposed bead cores constituting the annular second bead 1b. The winding member 17 may be provided. Examples of the constituent material of the winding member 17 include organic fibers such as rayon, nylon, polyester, and aramid, and steel cords. The fiber material constituting the winding member 17 is preferably arranged in the radial direction. According to such an embodiment, since the outer end in the tire width direction of the winding member 17 is locked between a pair of opposed bead cores (second beads 1b) opposed in the tire radial direction, the second bead 1b and A sufficient amount of rubber (rubber thickness) with the rim flange 8a can be secured. Thereby, even when a vertical high load is applied to the bead portion during traveling, the interference between the rim 8 and the second bead 1b is suppressed, and the first concentration while suppressing the concentration of strain on the carcass ply 14 and the winding member 17 is suppressed. The space between the bead 1a and the second bead 1b can be reinforced. Note that one end of the winding member 17 may be directly wound around the first bead 1a via the carcass ply 14 or may be indirectly wound via a rubber layer or the like.

  Examples that specifically show the structure and effects of the present invention will be described below. The tire bead durability was evaluated as follows.

  Each test tire (tire size 245 / 40R18) mounted on a standard rim is run for 4 hours on a drum with a diameter of 1700 mm at a tire internal pressure of 180 kPa and a speed of 80 km / h under 85% of the maximum load specified by JATMA. I let you. After running for 4 hours, the load was continuously changed to 90% of the maximum load specified by JATMA for 6 hours, and further, the load was changed to 100% of the maximum load specified by JATMA for 24 hours. . Thereafter, the running was continued while increasing the load by 20% of the maximum load specified by JATMA every 24 hours, and the test time until failure was confirmed was measured. The test time until failure was confirmed was indexed with the conventional example 1 as 100. The larger the value, the longer the test time, that is, the better the bead durability.

  As test tires, Conventional Example 1-2, Comparative Example 1 and Example 1-2 having different configurations were prepared. Conventional Example 1 has an annular second bead composed of a single core, and the end portion of the carcass ply wound up outside in the tire width direction by the annular first bead in the vicinity of the side portion of the bead filler via the steel side ply. However, the structure is the same as that of the run flat tire shown in FIG. 1 except that the second bead is disposed at substantially the same height position in the tire radial direction as the end on the tire inner periphery side. In Conventional Example 2, an annular second bead composed of a single core and a carcass ply wound up outward in the tire width direction by the annular first bead pass between the first bead and the second bead. The run flat tire shown in FIG. 1 except that the second bead is disposed along a route from the tire outer peripheral side of the second bead to the tire inner peripheral side of the second bead. A similar structure was adopted.

  In Comparative Example 1, an annular second bead composed of a pair of opposed bead cores facing each other in the tire width direction, and a carcass ply wound up outward in the tire width direction by the annular first bead are paired from the tire inner circumferential side. A run-flat tire having an outer end portion in the tire radial direction locked between the opposed bead cores (second beads) was obtained.

  In Example 1, as shown in FIG. 1, an annular second bead composed of a pair of opposed bead cores facing each other in the tire radial direction, and a carcass ply wound up outside in the tire width direction by the annular first bead, A run-flat tire having an outer end portion in the tire width direction locked between a pair of opposed bead cores (second beads) was obtained. In the second embodiment, as shown in FIG. 2, one end is disposed so as to wind an annular first bead from the tire inner peripheral side, and the other end is locked between a pair of opposed bead cores (second bead). A run-flat tire provided with a winding member (component member; steel reinforcing layer) arranged as described above was obtained. The results are shown in Table 1.

  Compared to the run-flat tires of Conventional Example 1-2 and Comparative Example 1, the run-flat tire of Example 1 has an excellent bead durability against a longitudinally high load, and thus a test until failure is confirmed. The time was long and the load at the time of failure was high. Therefore, it turns out that the run flat tire of Example 1-2 is excellent in bead durability.

  On the other hand, in the run flat tires of Conventional Example 1-2 and Comparative Example 1, the test time until failure is confirmed is shorter than that of the run flat tire of Example 1-2 due to separation by the carcass ply. It was. In the run-flat tire of Conventional Example 1, the distance between the rolled-up end of the carcass ply and the end of the other member such as the steel side ply is narrow, and the rolled-up end of the carcass ply is between the opposing bead cores (second bead). ), The winding end portion of the carcass ply is likely to be distorted when a longitudinally high load is applied. As a result, it is considered that a large shear strain was generated at the winding end of the carcass ply and separation was generated at the winding end of the carcass ply. In the run-flat tires of Conventional Example 2 and Comparative Example 1, since the carcass ply is disposed between the second bead and the rim flange, a sufficient amount of rubber is secured between the second bead and the rim flange. This is not possible, and the interference between the rim and the second bead is large at the time of a longitudinally high load. Thereby, distortion concentrates on the carcass ply extending in the width direction between the second bead and the rim flange. As a result, it is thought that the separation in the carcass ply occurred.

Half sectional view showing an example of a run flat tire according to the present invention Half sectional view showing an example of a run flat tire according to another embodiment Half sectional view showing an example of a conventional run flat tire

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bead part 1a 1st bead 1b 2nd bead 2 Side wall part 3 Tread part 4 Carcass layer 5 Inner liner layer 6 Belt layer 7 Belt reinforcement layer 8 Rim 8a Rim flange 8b Bead seat part 9 Reinforcement rubber layer 10 Annular bulging part 11 Pointed head 12 Bead filler 14 Carcass ply 16 Steel side ply 17 Winding member C Tire equator

Claims (2)

  A pair of bead portions each having an annular first bead, a sidewall portion extending outward in the tire radial direction from each of the bead portions, and spanned between the bead portions and wound up outward in the tire width direction by the first bead A carcass layer composed of the carcass ply formed, an annular bulging portion having an inner peripheral surface that bulges outward in the tire width direction from at least one of the bead portions and extends along the outer peripheral curved surface of the rim flange, and the annular bulging An annular second bead composed of a pair of opposed bead cores arranged in the tire and facing in the tire radial direction, and the rolled up carcass ply is locked between the pair of opposed bead cores in the tire width direction outside A run flat tire having an end.   The winding member according to claim 1, further comprising: a winding member disposed so that one end winds the first bead from the tire inner peripheral side and the other end is locked between the pair of opposed bead cores. Run flat tire.

Images