JP2006199111A - Pneumatic tire, and method for using pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire, and a method for using a pneumatic tire for improving a cord cutting property of a folded part of a carcass. <P>SOLUTION: This pneumatic tire has a flatness of 80% or less, and a cord constituting a folded part 5b is arranged at 0-10° relative to a radial direction. When a tire radial distance from the end of the folded part 5b to the rim side end of a bead core 6 is designated as CE and a flange height is designated as FH, the relationship of 2×FH<CE<6×FH is satisfied. When a tire width cross section, a distance between a carcass body part 5a and the folded part 5b on a vertical line relative to the carcass body part 5a is designated as t and a diameter of the cord constituting the folded part 5b is designated as a, the relationship of 3×a<t<5×a is satisfied in an area of 2×FH-4×FH in a tire radial direction from the rim side end of the bead core 6. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire for improving the cord breakability of a folded portion of a carcass and a method for using the pneumatic tire.

  Conventionally, there is a technique for improving the separation of the end of the carcass ply in order to improve the durability of the bead.

Specifically, a technique for providing an angle to the folded ply of the carcass (for example, refer to Patent Document 1 and Patent Document 2), or a technique having a shape that separates after the folded ply is once brought close to the carcass main body (for example, , See Patent Document 3.).
JP-A-11-170807 JP 2002-347409 A JP-A-1-111504

  On the other hand, in a heavy-duty construction vehicle tire or the like, there is a case where a large bead collapse deformation occurs due to the tire deflection, and the cord of the folded portion of the carcass may be cut. It has been difficult to cope with such code breakage with the above-described prior art.

  That is, in a tire to which the bent carcass technology disclosed in Patent Document 1 and Patent Document 2 is applied, the longitudinal spring coefficient of the tire is reduced. As a result, the bead collapse deformation due to tire deflection during load application increases, and the compression input to the carcass turn-up portion increases. For this reason, the breakage of the cord at the folded portion is likely to occur.

  Further, in a tire to which the technology for turning the folded carcass disclosed in Patent Document 3 is applied, the compression input to the folded carcass of the bent portion increases. For this reason, the breakage of the cord at the folded portion is likely to occur.

  Then, an object of this invention is to provide the usage method of the pneumatic tire which improves the cord breakability of the folding | turning part of a carcass, and a pneumatic tire in view of said problem.

  In order to solve the above-mentioned problem, the first feature of the present invention is that it extends in a toroid shape between bead cores embedded in a pair of bead portions, and extends from the inner side in the tire width direction around the bead core along the peripheral surface thereof. A pneumatic tire having a flat rate of 80% or less, including a carcass made of at least one carcass ply having a folded portion wound up outward or from the outside to the inside, and the cord constituting the folded portion is 2 × FH <CE <6, where the tire radial direction distance from the end of the folded portion to the rim side end of the bead core is CE and the flange height is FH. XFH, and in the cross section in the tire width direction, the distance between the carcass main body portion and the folded portion on the vertical line to the carcass main body portion is t, and the diameter of the cord constituting the folded portion is a If you, in the region of 2 × FH~4 × FH from the rim side end of the bead core in the tire radial direction, is summarized in that a pneumatic tire which satisfies the 3 × a <t <5 × a.

  According to the pneumatic tire according to the first feature, the folded portion is arranged in a range closer to the neutral surface (carcass main body portion) of the bending deformation than the conventional pneumatic tire, so that the folded portion is compressed when a load is applied. It is possible to reduce the input and improve the cord breakability of the folded portion of the carcass.

  The second feature of the present invention is that it extends in a toroid between bead cores embedded in a pair of bead portions, and extends from the inner side to the outer side in the tire width direction around the bead core, or from the outer side to the inner side. The carcass made of at least one carcass ply having a turned-up portion that is rolled up toward the surface, has a flatness of 80% or less, and the cords that make up the turned-up portion are arranged at 0 ° to 10 ° with respect to the radial direction When the distance in the tire radial direction from the end of the turn-up portion to the rim side end of the bead core is CE and the flange height is FH, 2 × FH <CE <6 × FH. When the distance between the carcass main body portion and the folded portion on the vertical line with respect to the portion is t, and the diameter of the cord constituting the folded portion is a, the tire radial direction from the rim side end of the bead core In the region of 2 × FH to 4 × FH, a method of using a pneumatic tire satisfying 3 × a <t <5 × a, where FH / SH <0.15 is satisfied when the section height is SH. The gist is that it is a method of using a pneumatic tire in which a pneumatic tire is assembled on a rim.

  According to the method for using the pneumatic tire according to the second feature, by assembling the rim having a low flange height, the range of flexural deformation is widened, and the meandering range of the folded portion when a load is applied can be reduced.

  ADVANTAGE OF THE INVENTION According to this invention, the usage method of the pneumatic tire which improves the cord breakability of the folding | turning part of a carcass and a pneumatic tire can be provided.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(Pneumatic tire structure)
As shown in FIG. 1, the pneumatic tire according to the embodiment of the present invention is connected to the tire equatorial plane CL in a toroid shape between the pair of bead portions 1 and the pair of sidewall portions and the sidewall portions. A tread portion. The pneumatic tire according to the present embodiment is a flat radial tire for a super heavy load construction vehicle having a flat rate of 80% or less. That is, a radial tire having a rim diameter of 57 "or more, a load carrying capacity of 60 mton or more, and a load factor (k-factor) of 1.7 or more.

  The carcass 5a, 5b extends in a toroidal shape between the bead cores 6 embedded in the pair of bead portions 1, respectively, and is wound around the bead core from the inner side to the outer side in the tire width direction along the circumferential surface thereof. It is a toroidal radial carcass that reinforces the sidewall portion and the tread portion. The carcass may be configured by winding from the outside toward the inside.

  The carcass 5a, 5b has a carcass main body 5a and a folded-back portion 5b, and is composed of at least one carcass ply. The code | cord | chord which comprises the folding | returning part 5b is arrange | positioned at 0 degrees-10 degrees with respect to the radial direction.

  As shown in FIG. 1, when the tire radial direction distance from the end of the folded portion 5b to the rim side end of the bead core 6 is CE and the flange height is FH, 2 × FH <CE <6 × FH. In the cross section in the tire width direction, when the distance between the carcass main body 5a and the folded portion 5b on the vertical line with respect to the carcass main body 5a is t and the diameter of the cord constituting the folded portion 5b is a, the bead core 6 In a region of 2 × FH to 4 × FH in the tire radial direction from the rim side end, 3 × a <t <5 × a is satisfied.

  Further, the pneumatic tire according to the present embodiment is used by being incorporated in a rim that satisfies FH / SH <0.15, where SH is the section height (tire cross-sectional height).

(Action and effect)
The deformation of the bead portion when a load is applied to a normal pneumatic tire will be described with reference to FIG.

  First, when no load is applied, the carcass main body 5a and the folded portion 5b are not subjected to bending deformation as shown in the left diagram of FIG.

  When a load is applied here, the bead portion is subjected to a large bending deformation due to falling. The neutral plane of the bending in this bending deformation is the carcass main body 5a. With the carcass main body 5a as the center, tensile input acts on the inner side in the tire width direction and compressive input acts on the outer side in the tire width direction. As shown in the right diagram of FIG. 2, a compression input is generated in the folding portion 5 b.

  As shown in FIG. 3A, when the folded portion 5b receives a compression input, the carcass cord made of metal cannot contract, and the folded portion 5b snakes to absorb the compression. As a result, as shown in FIG.3 (b), the folding | returning part 5b will meander in a tire circumferential direction surface. As described above, as a result of the meandering portion 5b meandering, a local compression input is generated in the filament in the carcass cord, and the filament is broken.

  As shown in FIG. 4, the pneumatic tire according to the present embodiment described above arranges the folded portion 5 b in a range closer to the neutral surface (carcass main body portion 5 a) of bending deformation than the conventional pneumatic tire. Thus, by reducing the compression input to the folded portion 5b, the meandering of the folded portion 5b can be reduced, and the filament breakage can be suppressed.

  In FIG. 2B, the carcass center line of the folded portion 5b when no load is applied is X, the carcass center line of the folded portion 5b when loaded is Y, the carcass cord diameter is a, and the carcass center of the folded portion 5b. Let the amount of meandering of the line be b. The time when the load is applied refers to a state in which the tire is deformed by applying a load of 80 to 120% relative to the normal load in a direction perpendicular to the tire rotation axis. Here, the “regular load” refers to the maximum load in the applicable size / ply rating defined in the 2004 version of YEAR BOOK issued by the US tire and rim association TRA. In FIG. 2B, when the meandering index Z = b / a is defined, the pneumatic tire according to the present embodiment can satisfy 0 <Z <0.5.

  In the pneumatic tire according to the present embodiment, when the distance in the tire radial direction from the end of the folded portion 5b to the rim side end of the bead core 6 is CE and the flange height is FH, 2 × FH <CE <6. XFH. By designing 2 × FH <CE, it is possible to prevent burst due to the folded portion 5b being pulled out from the bead core when a heavy load is input. By designing CE <6 × FH, the movement of the carcass main body 5a can be prevented. The end of the folded portion 5b can be arranged in a region where the influence is small, and the distortion at the end of the folded portion 5b can be reduced.

  Further, in the pneumatic tire according to the present embodiment, in the tire width direction cross section, the distance between the carcass main body portion 5a and the folded portion 5b on the vertical line with respect to the carcass main body portion 5a is t, and the cord constituting the folded portion 5b When the diameter is a, 3 × a <t <5 × a is satisfied in the region of 2 × FH to 4 × FH in the tire radial direction from the rim side end of the bead core 6. The region of 2 × FH to 4 × FH is a region where the compression deformation of the cord of the folded portion 5b is found to be maximum, and when t is smaller than 3 × a, the distortion between the plies increases, so that the separation is reduced. If it becomes easy to occur and t is larger than 5 × a, the folded portion 5b is arranged on the compression input side, and the code breakage is not improved.

  Further, the pneumatic tire according to the present embodiment is a flat for a super heavy load construction vehicle having a flatness ratio of 80% or less, a rim diameter of 57 "or more, a load load capacity of 60 mton or more, and a load factor (k-factor) of 1.7 or more. In such an ultra-large tire, the compression distortion of the folded-back portion 5b increases, so that the advantage of improving the cord breakability is remarkable by adopting the structure described in the present embodiment. It is.

  Further, the pneumatic tire according to the present embodiment can be used by being assembled on a rim that satisfies FH / SH <0.15 when the section height is SH. As described above, by assembling the rim having a low flange height, the range of the bending deformation is widened, and the meandering range of the folded portion when a load is applied can be reduced.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.

In order to confirm the effect of the present invention, pneumatic tires according to Examples and Conventional Examples were made as trial products. The size of each test tire was 59 / 80R63, and the rim size was 44 "x 5". The structure of the pneumatic tire according to the example and the conventional example is as shown in Table 1.

<Drum life evaluation>
The drum life test measures the distance until it becomes impossible to run due to a failure of the beat section (carcass ply cord breakage) at an air pressure of 600 kPa, a load of 150%, and a drum rotation speed of 8 km / h, and is indexed using the conventional tire as a control. It was evaluated by doing. The larger the value, the better the durability.

(result)
The results are shown in Table 2.

  It was found that the example is superior in the durability of the bead portion, that is, the cord breakability is improved as compared with the conventional example. Therefore, in the cross section in the tire width direction, when the distance between the carcass main body portion and the folded portion on the vertical line with respect to the carcass main body portion is t, and the diameter of the cord constituting the folded portion is a, the rim side end of the bead core In the region from 2 × FH to 4 × FH in the tire radial direction, the cord breakability is improved by satisfying 3 × a <t <5 × a and the meandering index Z being 0 <Z <0.5. I found out.

It is a bead part sectional view containing the tire rotation axis of the pneumatic tire concerning this embodiment. It is a figure for demonstrating a deformation | transformation of the bead part at the time of a load load (the 1). It is a figure for demonstrating a deformation | transformation of the bead part at the time of a load load (the 2). It is a figure for demonstrating a deformation | transformation of the bead part at the time of a load load (the 3).

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Bead part, 5 ... Carcass, 5a ... Carcass main-body part, 5b ... Fold-up part, 6 ... Bead core, 10 ... Flange

Claims (2)

A bead core extending in a toroid between the bead cores embedded in a pair of bead portions, and having a turn-up portion wound around the bead core from the inner side to the outer side in the tire width direction or from the outer side to the inner side along the circumferential surface. A pneumatic tire having a flat rate of 80% or less, comprising a carcass made of at least one carcass ply,
The cord constituting the folded portion is arranged at 0 ° to 10 ° with respect to the radial direction,
When the distance in the tire radial direction from the end of the folded portion to the rim side end of the bead core is CE and the flange height is FH, 2 × FH <CE <6 × FH,
In the cross section in the tire width direction, when the distance between the carcass main body portion on the vertical line to the carcass main body portion and the folded portion is t, and the diameter of the cord constituting the folded portion is a, the tire starts from the rim side end of the bead core. A pneumatic tire characterized by satisfying 3 × a <t <5 × a in a region of 2 × FH to 4 × FH in the radial direction. A bead core extending in a toroid between the bead cores embedded in a pair of bead portions, and having a folded portion wound around the bead core from the inner side to the outer side in the tire width direction or from the outer side to the inner side along the circumferential surface. A carcass made of at least one carcass ply,
Flatness is 80% or less,
The cord constituting the folded portion is arranged at 0 ° to 10 ° with respect to the radial direction,
When the distance in the tire radial direction from the end of the folded portion to the rim side end of the bead core is CE and the flange height is FH, 2 × FH <CE <6 × FH,
In the cross section in the tire width direction, when the distance between the carcass main body portion on the vertical line to the carcass main body portion and the folded portion is t, and the diameter of the cord constituting the folded portion is a, the tire starts from the rim side end of the bead core. In the region of 2 × FH to 4 × FH in the radial direction, a method of using a pneumatic tire satisfying 3 × a <t <5 × a,
When the section height is SH, the pneumatic tire is assembled on a rim that satisfies FH / SH <0.15.

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