JP2005199762A - Pneumatic radial tire for heavy load - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic radial tire for a heavy load capable of optimizing a providing position of a rewinding end of a carcass ply or a wire chafer end, preventing a crack from beginning at the end part, and improving durability in the part and in the whole tire by suppressing collapse of a side wall part and a bead part. <P>SOLUTION: The rewinding end of the carcass ply 1 is positioned within a range of ±5% of tire cross sectional height SH with a tire maximum width position SW as the center. A tire width direction inside end CI of a cord reinforcing layer 8 is positioned within the range of 30-50% of the height A of the maximum width position SW from a rim diameter line LA. A tire width direction outside end CO of the cord reinforcing layer 8 is positioned within the range of the height G or less of a flange of a suitable rim 9 from the rim diameter line L. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention mainly prevents crack growth from the end of a carcass ply or wire chafer, which is suitable for use in trucks, buses, construction vehicles, and the like. The present invention relates to a heavy-duty pneumatic radial tire that prevents falling of the bead portion and has improved durability.

  In the heavy-duty radial tire, as described in Patent Document 1, for example, a wire chafer is provided along the outer side of the turn-up portion of the carcass ply so that the carcass ply and the rim are not in direct contact with each other. It is generally done to protect. In such tires, especially those that are used multiple times as a correction tire after tread wear, the carcass ply rewinding end and wire chafer end such as the end of a wire chafer can be used for a long time. There was a problem that a crack occurred from a portion where stress was likely to concentrate, and that it was likely to become the core of separation.

  By the way, a reinforcing layer such as a carcass ply or a wire chafer has a function of suppressing the collapse of the sidewall portion and the bead portion during load rolling and improving the durability of the portion. For this reason, in order to secure the function, it is better to place the winding end of the carcass ply and the end of the wire chafer as far away from the rim diameter line as possible, but to suppress the occurrence of cracks from those ends. It is better to be as close to the rim diameter line as possible. And the knowledge for solving these conflicting problems has not been sufficiently obtained.

JP 2000-185516 A

  The object of the present invention is to solve such problems of the prior art, and the object of the present invention is to optimize the arrangement position of the winding end and the wire chafer end of the carcass ply. In addition, a heavy-duty pneumatic radial that prevents cracks from the edges and suppresses the falling of the sidewalls and beads to increase the durability of the parts and improve the durability of the entire tire. To provide tires.

A heavy-duty pneumatic radial tire according to the present invention has a tread rubber disposed on the outer peripheral side of a crown portion of a carcass in which one or more carcass plies are wound around a bead core and disposed on a toroid. A belt composed of one or more belt layers is disposed between the belt and the carcass, and the cord reinforcing layer is wound around the bead core along the outside of the wound portion of the carcass ply. ,
The carcass ply winding end is positioned within a range of ± 5% of the tire cross-section height centered on the tire maximum width position,
The inner end of the cord reinforcing layer in the tire width direction is positioned within a range of 30 to 50% of the maximum width position height from the rim diameter line,
The outer end in the tire width direction of the cord reinforcing layer is positioned within the range of the height of the flange of the applicable rim from the rim diameter line.

According to the present invention, the turn-up end of the carcass ply is positioned within a range of ± 5% of the tire cross-sectional height with the tire maximum width position as the center, thereby suppressing the collapse of the sidewall portion. The durability of the tire as a whole can be improved by balancing the effect of increasing the durability of the portion with the effect of suppressing the cracking at the winding end.
When the carcass ply turn-up end is positioned in a range that exceeds + 5% of the tire cross-section height centered on the maximum tire width position, the sidewall stiffness is suppressed by increasing the shear rigidity in the cross-section in the tire width direction. The effect of increasing the durability of the sidewall portion can be enhanced, but the disadvantage is that the circumferential shear strain that occurs during rolling of the tire increases in the vicinity of the winding end of the carcass ply, and cracks are likely to occur. Occurs.

In addition, if the turn-up end of the carcass ply is positioned in a range exceeding −5% of the tire cross-section height with the tire maximum width position as the center, the circumferential shear strain generated at the turn-up end portion during tire rolling is reduced. Although it can be suppressed, the shear rigidity of the sidewall portion in the cross section in the tire width direction is lowered, and the effect of increasing the durability of the sidewall portion by suppressing the collapse of the sidewall portion is lowered.
Here, the sign “+” indicates the outer side in the tire radial direction, and “−” indicates the inner side in the tire radial direction.

  Furthermore, the cord reinforcement layer is positioned in the tire width direction inner end within the range of 30 to 50% of the maximum width position height from the rim diameter line, thereby suppressing the collapse of the sidewall portion and the bead portion due to the cord reinforcement layer. As a result, the durability of the sidewall portion and the bead portion can be improved, and the shear strain generated at the end of the cord reinforcing layer itself can be suppressed.

If the inner end of the cord reinforcing layer in the tire width direction is positioned in a range exceeding 50% of the maximum width position height from the rim diameter line, the shear strain near the inner end of the cord reinforcing layer in the tire width direction when collapsed is large. As a result, the durability of the tire decreases.
Further, when the inner end of the cord reinforcing layer in the tire width direction is positioned within a range of less than 30% of the maximum width position height from the rim diameter line, the shear rigidity in the tire width direction cross section of the bead portion becomes too small, The effect of increasing the durability of the sidewall portion and the bead portion by suppressing the collapse of the sidewall portion and the bead portion becomes too small.

Furthermore, by positioning the outer end in the tire width direction of the cord reinforcing layer within the range of the rim diameter line or less than the height of the flange of the applicable rim, the bead portion collapses during tire load rolling and the cord reinforcing layer It is possible to prevent the occurrence of cracks due to the concentration of strain at the outer end in the tire width direction by suppressing the collapse of the outer end in the tire width direction of the cord reinforcing layer with the rigid support of the flange of the rim.
If the outer edge in the tire width direction of the cord reinforcement layer is positioned beyond the height of the flange of the applicable rim from the rim diameter line, strain concentrates on the outer edge in the tire width direction of the cord reinforcement layer when the bead part collapses and cracks Is likely to occur.

Here, the tire cross-sectional height is a value obtained by subtracting the rim diameter from the outer diameter of the tire that is mounted on the applicable rim, filled with the specified air pressure, and in a no-load state, and then halved. Say.
The standard is determined by an industrial standard effective in the region where the tire is produced or used. For example, “THE TIRE and RIM ASSOCIATION INC. YEAR BOOK” in the United States, “The European Tire and Rim Technical Organization STANDARDS MANUAL” in Europe, and “JATMA YEAR BOOK” from the Japan Automobile Tire Association in Japan. .

The maximum width position height refers to the distance in the tire radial direction from the rim diameter line at the maximum width position of the sidewall portion, and the rim diameter line refers to a line corresponding to the rim diameter.
Further, the flange height refers to the radial distance from the rim diameter line of the flange.
Further, the cord reinforcing layer refers to, for example, a wire chafer or the like, and is provided to protect the carcass ply so that the carcass ply does not directly touch the rim.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view in the width direction of a tread portion showing an embodiment of the present invention with respect to a half portion of a tire in which a tire is mounted on an applicable rim and filled with a prescribed air pressure. In the figure, 1 indicates a carcass ply.

  Here, four belt layers 3, 4, 5, 6 are arranged on the outer peripheral side of the crown portion of the carcass ply 1, which extends in a toroidal shape between the bead cores 2 and whose side portions are wound around the bead cores 2. In addition, the tread rubber 7 is disposed on the outer peripheral side of the belt layer 6. Further, a wire chafer 8 serving as a cord reinforcing layer is provided around the bead core 2 so as to be wound around the outside of the turned-up portion of the carcass ply 1 around the bead core 2.

Further, the turning end PE of the carcass ply 1 is positioned within a range of ± 5% of the tire cross-section height SH with the tire maximum width position SW as the center (here, 0%)
The inner end CI of the wire chafer 8 in the tire width direction is positioned within a range of 30 to 50% of the maximum width position height H from the rim diameter line L (the tire radial distance from the rim diameter line L of the CI is WE Then, 0.3 ≦ WE / H ≦ 0.5),
The outer end CO in the tire width direction of the wire chafer 8 is positioned from the rim diameter line L to a range not more than the height G of the flange of the applied rim 9 indicated by a two-dot chain line in the figure (CO rim diameter line L If the distance in the tire radial direction from WS is WS, WS ≦ G).

Below, the example of the tire concerning the present invention is described.
For the purpose of evaluating the durability of the tire according to the present invention, Example tire 1 and Comparative example tires 1 to 3 having a size of 11.00 R20 16PR RIB PATTERN shown in FIG. 1 and Table 1 are prepared as test tires. In addition, the rim is assembled to a rim of 8.00 V, the filling air pressure is set to 775 kPa, the test speed is 60 km / h, 1ST step (6050 kg, 144H), 2ND step (6510 kg, 72H), 3RD step (6980 kg, 72H), 4TH A drum test running test was performed according to the test load cycle of step (7440 kg, 72H), and a running distance until a crack occurred and a failure location were measured for each tire.
The results are shown in Table 1 and FIG.

According to the place shown in Table 1, the tire 1 has a longer mileage until cracking occurs than the comparative tires 1 to 3, and suppresses the cracking and increases the durability of the tire. You can see that
The comparative example tire 1 is cracked because the height WS from the rim diameter line of the widthwise outer side end CO of the wire chafer is smaller than the height G of the rim flange (44.5 mm for the rim of JATMA 8.00V). It turns out that it is easy to occur.

Further, in the comparative tire 2, the height WS from the rim diameter line of the widthwise inner end CI of the wire chafer is higher than 50% of the height A of the maximum width position SW, so that cracks are likely to occur. You can see that
Further, in the comparative example tire 3, the height WS from the rim diameter line of the widthwise inner end CI of the wire chafer is lower than 30% of the height A of the maximum width position SW, so that cracks are likely to occur. You can see that

  The present invention is a heavy-duty pneumatic radial that suppresses the occurrence of cracks at the end of the carcass ply winding and the end of the cord reinforcement layer and suppresses the collapse of the sidewall portion and the bead portion, thereby improving the durability of the tire. It is effective when applied to tires.

1 is a cross-sectional view in the width direction of a tread portion showing an embodiment of the present invention with respect to a half portion of a tire. It is a graph shown about the test result of the Example of this invention.

Explanation of symbols

1 Carcass ply 2 Bead core 3 Belt layer 4 Belt layer 5 Belt layer 6 Belt layer 7 Tread rubber 8 Wire chafer 9 Applicable rim PE Carcass ply rewind end L Rim diameter line H Tire radial distance SW from the rim diameter line of the PE Tire radial direction distance CI from the rim diameter line of the maximum tire width position A SW Inner inner end CO of the tire width direction cross section of the wire chafer CO Inner outer end G of the cross section of the tire width direction of the wire chafer G Flange height WE Rim diameter of the CI Tire radial distance WS from line WS Tire radial distance from CO rim diameter line

Claims (1)

A tread rubber is disposed on the outer peripheral side of the crown portion of the carcass formed by winding one or more carcass plies around the bead core and disposed on the toroid, and one or more belt layers are provided between the tread rubber and the carcass. A heavy-duty pneumatic radial tire in which a belt made of the belt is disposed, and the cord reinforcing layer is wound around the bead core along the outside of the turned-up portion of the carcass ply,
The carcass ply winding end is positioned within a range of ± 5% of the tire cross-section height centered on the tire maximum width position,
The inner end of the cord reinforcing layer in the tire width direction is positioned within a range of 30 to 50% of the maximum width position height from the rim diameter line,
A heavy-duty pneumatic radial tire in which the outer end in the tire width direction of the cord reinforcing layer is positioned within the range of the rim diameter line or less than the height of the flange of the applicable rim.

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