JP2005096621A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving a performance on snow while securing dry/wet performances. <P>SOLUTION: A tread 12 is provided with a plurality of slant lateral grooves 16 slanting and extending in the circumferential direction of the tire from a ground end 12E to a tire equator CL to designate the directionality, which provides the high wet performance. When the tire is traveling on snow, the snow coming into the slant lateral grooves 16 gives the snow column shearing force to the tire. The basic performance for traveling on a road surface covered with snow can be obtained thereby. In a land part 18 sandwiched between the adjacent slant lateral grooves 16 in the circumferential direction, a convex curve thin groove 20 and a sipe 20 are formed on a step-in side for obtaining large edge effect at the time of stepping-in on the snow, which improves a traction performance on the snow. A kick-out side of the land part 18 has less grooves and higher land part stiffness than those of the step-in side, which secures the land part stiffness of the whole land part to secure the dry/wet steering performances. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire in which a cord reinforcing layer is provided on an outer peripheral surface of a carcass disposed in a bead portion in order to prevent failure of the bead portion.

  In general, in a heavy duty pneumatic tire, a cord reinforcing layer in which a plurality of steel cords called wire chafers are coated with a coating rubber is provided on the outer surface of the carcass for the purpose of increasing the durability of the bead portion.

An inner liner is provided on the inner peripheral surface of the tire of the carcass in order to suppress permeation of the filled air (see, for example, Patent Document 1).
JP 7-502471A

  For example, in the pneumatic tire described in JP 7-502471A, the internal rubber (6) and the impermeable mixture (8) correspond to the inner liner.

  The inner liner uses butyl rubber to suppress air permeation, but butyl rubber has a low adhesive strength, so the carcass and the inner liner are bonded together by an adhesive layer.

  By the way, when the tire rolls under load, the bead portion collapses at the time of grounding, and the wire chafer end is distorted.

  The distortion at the end of the wire chafer is caused by the movement of the wire due to deformation such as a load, and this causes shear strain in the coating rubber, the adhesive layer, and the inner liner.

  However, since the inner liner has low adhesive strength (as compared with the coating rubber of the wire chafer), if the shear strain increases, a peeling failure may occur between the inner liner and the adhesive layer.

  Further, since the adhesive layer is more easily deteriorated by the atmosphere than rubber, when the end portion of the adhesive layer is exposed on the tire surface, the adhesive layer starts to deteriorate from the end portion exposed on the tire surface.

  In view of the above fact, an object of the present invention is to provide a pneumatic tire capable of suppressing a peeling failure between an inner liner and an adhesive layer.

  The pneumatic tire according to claim 1 is an inner liner disposed on an inner surface of the tire, an adhesive layer disposed on an outer peripheral surface of the inner liner, a bead core disposed in a bead portion, and a periphery of the bead core. A cord reinforcing layer in which a plurality of cords are coated with a coating rubber, and are provided along the outer surface of the carcass ply in the bead portion so as to straddle both sides of the carcass main body side and the folding side. The end of the adhesive layer is terminated in the bead portion without being exposed on the tire surface, the diameter of the cord is D, and the gauge between the cord and the inner liner is W, A pneumatic tire characterized by satisfying 0.5D ≦ W ≦ 4D.

  Next, the operation of the pneumatic tire according to claim 1 will be described.

  When the relationship between the cord diameter D of the cord reinforcing layer and the gauge W between the cord and the inner liner satisfies 0.5D ≦ W ≦ 4D, a rubber gauge from the cord of the cord reinforcing layer to the inner liner is secured. Shear strain is relieved and peeling failure between the adhesive layer and the inner liner can be suppressed. Further, even if a crack occurs at the end of the cord reinforcing layer, it is possible to suppress the crack generated at the end of the cord reinforcing layer from progressing to the adhesive layer side.

  If 0.5D> W, the shear strain cannot be sufficiently relaxed.

  On the other hand, when W> 4D, the gauge between the cord and the inner liner becomes too thick, and the material is used more than necessary and is wasted.

  The inner liner is generally made of butyl rubber, which is one of the rubbers with a weak adhesive strength. Cobalt blended natural rubber or the like is used as an adhesive layer for bonding such an inner liner to other rubber.

  Cobalt-blended natural rubber is more susceptible to atmospheric degradation than other rubbers, but in this pneumatic tire, the end of the adhesive layer terminates in the bead without being exposed to the tire surface, so the adhesive layer The atmospheric deterioration of can be suppressed.

  The invention according to claim 2 is the pneumatic tire according to claim 1, wherein when the tire cross-section height is H, the rim diameter measurement position extends outward in the tire radial direction from H / 6 to H / 3. W ≧ 1.8D is satisfied in the range below, and W ≧ 1.6D is satisfied in the range from H / 3 to H / 2 from the rim diameter measurement position to the outer side in the tire radial direction.

  Next, the operation of the pneumatic tire according to claim 2 will be described.

  W ≧ 1.8D is satisfied from the rim diameter measurement position to the outer side in the tire radial direction over H / 6 and less than H / 3, and from the rim diameter measurement position to the outer side in the tire radial direction from H / 3 to H / 2. If W ≧ 1.6D is satisfied in the range, the gauge between the cord and the inner liner is further optimized, and cracks generated from the cord are suppressed.

  Since the pneumatic tire according to the present invention has the above-described configuration, it is possible to suppress a peeling failure between the adhesive layer and the inner liner, and to suppress a crack generated at the end of the cord reinforcing layer from progressing to the adhesive layer side. , Has an excellent effect.

  A pneumatic tire (tire size 295 / 75R22.5) 10 according to an embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 1, the carcass ply 12 of the pneumatic tire 10 is composed of a carcass ply cord extending in the radial direction and a coating rubber covering the carcass ply cord.

  The coating rubber of this embodiment for covering the carcass ply cord is preferably a natural rubber containing cobalt.

  Both sides of the carcass ply 12 in the tire width direction (only one of them is shown in FIG. 1) are folded back from the tire inner side toward the outer side around the bead core 14 having a substantially hexagonal cross-sectional shape along the tire axial direction. It is.

  A stiffener 20 for maintaining high rigidity of the bead portion 18 is disposed in an area surrounded by the body ply 12A and the folded ply 12B of the carcass ply 12.

  Inside the bead portion 18, a wire chafer 24 is disposed adjacent to the side of the carcass ply 12 opposite to the bead core 14 side.

  As shown in FIG. 2, the wire chafer 24 is composed of a steel cord 24A inclined with respect to the tire radial direction and a coating rubber 24B covering the steel cord 24A.

  The coating rubber 24B of this embodiment is preferably a natural rubber containing cobalt.

  As shown in FIGS. 1 and 2, an inner liner 26 made of butyl rubber is provided on the innermost side of the pneumatic tire 10.

  As shown in FIG. 1, the end portion 26 </ b> E of the inner liner 26 terminates on the outer side in the tire radial direction than the bead toe 18 </ b> A of the bead portion 18.

  An adhesive layer 28 is provided on the tire outer surface side of the inner liner 26.

  The adhesive layer 28 bonds the carcass ply 12 and the inner liner 26, and the wire chafer 24 and the inner liner 26 to each other.

  The thickness of the adhesive layer 28 is preferably 2 ± 0.4 mm.

  As shown in FIG. 2, when D is the diameter of the steel cord 24A of the wire chafer 24 and W is the gauge between the steel cord 24A and the inner liner 26, 0.5D ≦ W ≦ 4D may be satisfied. preferable.

  Further, as shown in FIG. 3, when the tire cross-sectional height of the pneumatic tire 10 is H, W ≧ in the range from the rim diameter measurement position to the outer side in the tire radial direction beyond H / 6 and less than H / 3. 1.8D is satisfied, and it is preferable that W ≧ 1.6D is satisfied in the range from H / 3 to H / 2 from the rim diameter measurement position to the outer side in the tire radial direction.

  As shown in FIG. 1, the adhesive layer 28 is located on the outer side in the tire radial direction from the end portion of the inner liner 26, and is terminated in the bead portion 18 (the end portion is denoted by reference numeral 28E) so as not to be exposed on the tire surface. Yes.

  In the present embodiment, the first organic fiber cord layer 30 is disposed adjacent to the outer surface side of the wire chafer 24, and the second organic fiber cord layer 32 is disposed on the outer surface side of the first organic fiber cord layer 30. However, as shown in FIG. 4, the second organic fiber cord layer 32 may not be provided on the outer surface side of the first organic fiber cord layer 30.

Note that the first organic fiber cord layer 30 and the second organic fiber cord layer 32 are, for example, rubber-coated organic fiber cords such as nylon weave.
(Function)
Next, the operation of this embodiment will be described.

  When the pneumatic tire 10 rolls under load, the bead portion 18 repeatedly falls, and the end portion of the wire chafer 24 is distorted. As a result, shear strain is generated in the coating rubber 24B, the adhesive layer 28, and the inner liner 26. .

  In the present embodiment, the relationship between the diameter D of the steel cord 24A and the gauge W between the cord and the inner liner is 0.5D ≦ W ≦ 4D, and further exceeds H / 6 from the rim diameter measurement position to the outer side in the tire radial direction. Therefore, W ≧ 1.8D is satisfied in the range below H / 3, and W ≧ 1.6D is satisfied in the range from H / 3 to H / 2 from the rim diameter measurement position to the outer side in the tire radial direction. The rubber gauge W from the steel cord 24 </ b> A to the inner liner 26 becomes optimal, the shear strain during this is relieved, and a peeling failure between the adhesive layer 28 and the inner liner 26 can be suppressed.

  Further, even when peeling occurs at the end of the wire chafer 24 due to distortion during rolling, the peeling can be prevented from cracking and progressing to the adhesive layer 28 side.

  If 0.5D> W, the shear strain cannot be sufficiently relaxed.

  On the other hand, when W> 4D, the gauge W between the cord and the inner liner becomes too thick, and the material of the adhesive layer 28 is used more than necessary and is wasted.

  A coating rubber 24B and an adhesive layer 28 of the wire chafer 24 are interposed between the steel cord 24A and the inner liner 26, and the gauge W includes a gauge of the coating rubber 24B and a gauge of the adhesive layer 28. However, since it is not preferable to increase the thickness of the coating rubber 24B in terms of manufacturing and cost, the specification of the wire chafer 24 is not changed to satisfy 0.5D ≦ W ≦ 4D. It is better to adjust the gauge of layer 28.

It is sectional drawing of the bead part of the pneumatic tire which concerns on one Example of this invention. It is an expanded sectional view near an adhesive layer. It is sectional drawing along the rotating shaft of a pneumatic tire. It is sectional drawing of the bead part of the pneumatic tire which concerns on other embodiment.

Explanation of symbols

10 Pneumatic tire 12 Carcass ply 14 Bead core 24 Wire chafer (cord reinforcement layer)
24A Steel cord 26 Inner liner 28 Adhesive layer

Claims (2)

An inner liner disposed on the inner surface of the tire;
An adhesive layer disposed on the outer peripheral surface side of the inner liner;
A bead core disposed in the bead portion;
A carcass folded around the bead core and locked;
A cord reinforcing layer provided along the outer surface of the carcass ply in the bead portion so as to straddle both sides of the carcass main body side and the folded side, and a plurality of cords covered with a coating rubber; and
The end portion of the adhesive layer terminates in the bead portion without being exposed on the tire surface,
A pneumatic tire characterized by satisfying 0.5D ≦ W ≦ 4D, where D is a diameter of the cord and W is a gauge between the cord and the inner liner. When the tire cross-section height is H, W ≧ 1.8D is satisfied in the range from the rim diameter measurement position to the outer side in the tire radial direction beyond H / 6 to less than H / 3, and from the rim diameter measurement position to the tire diameter 2. The pneumatic tire according to claim 1, wherein W ≧ 1.6D is satisfied in a range of H / 3 or more and H / 2 or less outward in the direction.

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