JP2020168965A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire capable of improving the durability of a bead portion.SOLUTION: In a pneumatic tire having a structure in which a carcass layer 4 including a steel cord is wound up from a tire inside to an outside around a bead core 5 of each bead part 3, a first non-metal reinforcement layer 12A is arranged outside a tire width direction of a steel reinforcement layer 11 arranged in each bead part 3, the winding up height PLYh[mm] of a higher wound up edge part between the carcass layer 4 and the steel reinforcement layer 11, and the height CHFh1[mm] of an edge part 12e outside a tire radial direction in the first non-metal reinforcement layer 12A satisfy a relation of PLYh-15≤CHFh1≤PLYh, an edge part 12e inside the tire radial direction of the first non-metal reinforcement layer 12A is located in an area inside a tire width direction from a line segment G, and the first non-metal reinforcement layer 12A is arranged separately from an external surface of the bead part 3 by 1.5 mm or more.SELECTED DRAWING: Figure 3

Description

The present invention relates to a pneumatic tire having a structure in which a carcass layer including a steel cord is wound around the bead core of each bead portion from the inside to the outside of the tire, and more specifically, it is possible to improve the durability of the bead portion. Regarding pneumatic tires.

In a pneumatic tire, the carcass layer line (so-called balanced carcass line) protruding outward in the tire width direction is a profile with little shape change due to pneumatic filling. This balanced carcass line is excellent in improving the durability of the bead portion because the strain amplitude at the winding end of the carcass layer is suppressed, but the balanced carcass line has not been realized especially around the bead portion. ..

In pneumatic tires for heavy loads used for trucks, buses, etc., a carcass layer containing a plurality of aligned steel cords is mounted between a pair of bead portions, and the carcass layer is the bead core of each bead portion. Some tires have a structure that is wound from the inside to the outside of the tire. On the outer side of each bead portion in the width direction, a single steel reinforcing layer including a plurality of aligned steel cords may be arranged for the purpose of improving the durability of the bead portion. However, when a steel reinforcing layer is embedded in the bead portion, the rubber on the side of the bead core flows into the side of the end portion of the carcass layer during vulcanization, and the bead filler tends to be crushed from both sides in the tire width direction. is there. As a result, there is a problem that the bead filler has a rubber flow to the top side of the bead filler to be thinned, and the durability of the bead portion is lowered.

Further, in each bead portion, at least one organic fiber reinforcing layer including a plurality of aligned organic fiber cords is arranged on the outer side in the width direction of the bead filler for the purpose of improving the durability of the bead portion. In some cases (see, for example, Patent Document 1). However, when the organic fiber reinforcing layer is embedded in the bead portion, the bead filler tends to be crushed from both sides in the tire width direction due to the rigidity of the organic fiber reinforcing layer during vulcanization. As a result, there is a problem that the bead filler has a rubber flow to the top side of the bead filler to be thinned, and the durability of the bead portion is lowered.

Japanese Unexamined Patent Publication No. 63-110006

An object of the present invention is to provide a pneumatic tire capable of improving the durability of a bead portion.

In order to achieve the above object, the pneumatic tire of the present invention includes a tread portion extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and these sidewall portions. It is provided with a pair of bead portions arranged inside in the radial direction of the tire, and a carcass layer containing a plurality of steel cords is mounted between the pair of bead portions, and the carcass layer is placed around the bead core of each bead portion. In a pneumatic tire having a structure wound from the inside to the outside, a bead filler is arranged on the outer periphery of the bead core of each bead portion, and a steel reinforcing layer containing a plurality of steel cords in each bead portion is the carcass layer, the said. The bead core and the bead filler are arranged so as to wrap around the bead filler, the first non-metal reinforcing layer is arranged outside the steel reinforcing layer in the tire width direction, and the higher winding end portion of the carcass layer and the steel reinforcing layer is arranged. The relationship between the hoisting height PLY _h [mm] and the height CHF _h1 [mm] of the outer end portion of the first non-metal reinforcing layer in the tire radial direction is PLY _h- 15 ≤ CHF _h1 ≤ PLY _h . When the line segment G is defined as the line segment connecting the center of the strand F located on the outermost side in the tire width direction and the apex of the bead heel of the bead portion among the plurality of strands forming the bottom surface of the bead core. , The inner end portion of the first non-metal reinforcing layer in the tire radial direction is located in the region inside the tire width direction with respect to the line segment G, and the first non-metal reinforcing layer is from the outer surface of the bead portion. It is characterized in that it is arranged at a distance of 1.5 mm or more.

In the present invention, a bead filler is arranged on the outer periphery of the bead core of each bead portion, and a steel reinforcing layer containing a plurality of steel cords is arranged in each bead portion so as to wrap the carcass layer, the bead core and the bead filler to reinforce the steel. The first non-metal reinforcing layer is arranged on the outer side of the layer in the tire width direction, and the hoisting height PLY _h [mm] of the carcass layer and the steel reinforcing layer, whichever has the higher winding end, and the first non-metal reinforcing layer. The height of the outer end portion in the tire radial direction in the layer CHF _h1 [mm] is lateral to the bead core based on the first non-metal reinforcing layer by satisfying the relationship of PLY _h -15 ≤ CHF _h1 ≤ PLY _h. Since the rubber flow is suppressed, the rubber thickness from the winding end of the carcass layer to the outer surface of the bead can be reduced, and the bead filler due to the addition of the first non-metal reinforcing layer. It is possible to suppress the thinning of the tire and the flow of rubber to the top side of the bead filler. As a result, the equilibrium carcass line is approached around the bead portion, so that the durability of the bead portion can be improved. Since the rubber flow in the bead filler during vulcanization is suppressed as described above, the cost can be suppressed to the same level as that of a pneumatic tire having no non-metal reinforcing layer.

Further, since the inner end of the first non-metal reinforcing layer in the tire radial direction is located in the region inside the tire width direction with respect to the line segment G, the first non-metal reinforcing layer is located on the side of the bead core where a violent rubber flow occurs during vulcanization. Since one non-metal reinforcing layer is arranged, the rubber flow of the rim cushion rubber layer arranged on the side of the bead core can be significantly suppressed. As a result, the rubber flow from the side of the bead core to the winding end of the carcass layer can be suppressed, so that the rubber flows closer to the equilibrium carcass line and contributes to the improvement of the durability of the bead portion. Furthermore, since the first non-metal reinforcing layer is arranged at a distance of 1.5 mm or more from the outer surface of the bead portion, the first non-metal reinforcing layer does not come into direct contact with the rim, so that the bead portion and the rim flange The tension caused by the contact with the first non-metal reinforcing layer is relaxed, and the separation from the end portion of the first non-metal reinforcing layer can be suppressed.

In the present invention, the hoisting height PLY _h of the carcass layer and the steel reinforcing layer, whichever has the higher hoisting end, is preferably 25 mm to 45 mm. Thereby, the separation from the end portion of the carcass layer, the steel reinforcing layer or the first non-metal reinforcing layer can be effectively suppressed.

The winding end of the carcass layer is higher than the winding end of the steel reinforcing layer, and the shortest distance L between the tire radial outer end of the first non-metal reinforcing layer and the winding end of the carcass layer is 2 mm or more. Is preferable. As a result, the stress at the end of the first non-metal reinforcing layer can be dispersed, and the separation from the end of the first non-metal reinforcing layer can be effectively suppressed.

The shortest distance from the line segment J is the shortest distance from the line segment J with respect to the direction perpendicular to the line segment J connecting the center of the wire located on the innermost side in the tire radial direction and the bead toe of the bead portion among the plurality of wires constituting the bead core. When the region of -8 mm to 8 mm is defined as the region X, it is preferable that the end portion of the first non-metal reinforcing layer on the inner side in the tire radial direction is arranged in the region X. As a result, since the first non-metal reinforcing layer is arranged in the lower part of the bead core, the compressive strain of the rubber in the lower part of the bead core increases during vulcanization, and the position of the bead core can be moved toward the bead toe side. As a result, it contributes to the realization of an equilibrium carcass line around the bead portion, leading to an improvement in the durability of the bead portion.

The crack suppression layer located between the sidewall rubber layer exposed on the outer surface of the tire from the sidewall portion to the bead portion and the bead filler is the winding end of the carcass layer, the winding end of the steel reinforcing layer, and the first non-metal. Arranged so as to cover the outer end of the reinforcing layer in the tire radial direction, the 100% modulus Kc _M100 of the crack suppressing layer is 4.5 MPa to 10.0 MPa, and the breaking elongation Kc _EB of the crack suppressing layer is 300% or more. It is preferable to have. Thereby, the separation from the end portion of the carcass layer or the first non-metal reinforcing layer can be effectively suppressed.

The first non-metal reinforcing layer is preferably made of a plain woven fabric having a warp and weft fiber structure of 200/1 [dtex / piece] to 1000/1 [dtex / piece]. Thereby, the rubber flow can be suppressed regardless of the fiber direction of the first non-metal reinforcing layer. Further, the thickness of the first non-metal reinforcing layer can be reduced.

The first non-metal reinforcing layer is preferably made of a bamboo blind fabric having a fiber structure of 800/2 [dtex / piece] to 1500/2 [dtex / piece]. As a result, the rigidity step with the rubber at the end of the first non-metal reinforcing layer can be reduced as compared with the case of the plain woven fabric, so that the separation from the end of the first non-metal reinforcing layer is effective. Can be suppressed.

The driving density of the fiber cord of the bamboo blind fabric is preferably 10 lines / 50 mm to 40 lines / 50 mm. Thereby, the separation from the end portion of the first non-metal reinforcing layer can be effectively suppressed.

It is preferable that the inclination angle of the fiber cord forming the bamboo blind fabric with respect to the tire circumferential direction is 15 ° to 70 °, and the orientation direction of the fiber cord of the bamboo blind fabric is opposite to that of the steel cord of the steel reinforcing layer. Thereby, the rubber flow can be effectively suppressed.

A second non-metal reinforcing layer is adjacent to the outside of the first non-metal reinforcing layer in the tire width direction on the side of the winding end of the steel reinforcing layer, and the winding end of the carcass layer is the winding of the steel reinforcing layer. Higher than the end, the hoisting height PLY _h of the winding end of the carcass layer and the height CHF _h2 of the outer end in the tire radial direction in the second non-metal reinforcing layer are PLY _h- 23 ≤ CHF _h2 ≤ Satisfying the relationship of PLY _h- 8, the inner end of the second non-metal reinforcing layer in the tire radial direction is separated from the inner end of the first non-metal reinforcing layer in the tire radial direction by 4 mm or more, and the second The non-metal reinforcing layer is preferably arranged at a distance of 1.5 mm or more from the outer surface of the bead portion. Thereby, the durability of the bead portion can be effectively improved.

In the present invention, 100% modulus and elongation at break are measured according to JIS-K6251.

It is a meridian cross-sectional view which shows the pneumatic tire for heavy load which concerns on embodiment of this invention. It is sectional drawing which shows the bead part of the pneumatic tire of FIG. It is another cross-sectional view which shows the bead part of the pneumatic tire of FIG. It is a side view which shows by extracting the non-metal reinforcing layer and the steel reinforcing layer embedded in the bead part. It is sectional drawing which shows the modification of the bead part. It is sectional drawing which shows the other modification of the bead part.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a pneumatic tire for heavy load according to the embodiment of the present invention, and FIGS. 2 to 4 show a main part thereof.

As shown in FIG. 1, the pneumatic tire of the present embodiment has a tread portion 1 extending in the tire circumferential direction and forming an annular shape, and a pair of sidewall portions 2 and 2 arranged on both sides of the tread portion 1. And a pair of bead portions 3 and 3 arranged inside the sidewall portions 2 in the tire radial direction.

A carcass layer 4 is mounted between the pair of bead portions 3 and 3. The carcass layer 4 includes a plurality of steel cords extending in the radial direction of the tire, and has a structure in which the carcass layer 4 is wound around the bead core 5 arranged in each bead portion 3 from the inside to the outside of the tire. A bead filler 6 made of a rubber composition having a triangular cross section is arranged on the outer periphery of the bead core 5.

A four-layer belt layer 7 is embedded on the outer diameter side of the carcass layer 4 in the tread portion 1. Each belt layer 7 includes a plurality of belt cords (steel cords) that are inclined with respect to the tire circumferential direction. These belt layers 7 include main belt layers 72 and 73 of two central layers in which belt cords intersect with each other, and auxiliary belt layers 71 and 74 arranged on the inner diameter side and the outer diameter side of these main belt layers 72 and 73. Have. The inclination angle of the belt cords constituting the main belt layers 72 and 73 with respect to the tire circumferential direction is set in the range of, for example, 15 ° to 35 °, and the inclination angle of the belt cords forming the auxiliary belt layers 71 and 74 with respect to the tire circumferential direction is set. For example, it is set in the range of 15 ° to 75 °.

In the pneumatic tire, as shown in FIG. 2, the winding end portion 4e of the carcass layer 4 is arranged on the inner diameter side of the outer diameter side end portion 6e of the bead filler 6, that is, the winding end portion 4e of the carcass layer 4 Is terminated at the middle portion of the bead filler 6. In each bead portion 3, a steel reinforcing layer 11 including a plurality of steel cords is arranged so as to wrap the carcass layer 4, the bead core 5, and the bead filler 6. Further, in each bead portion 3, at least one non-metal reinforcing layer 12 (first non-metal reinforcing layer 12A) is arranged outside the steel reinforcing layer 11 in the tire width direction (one layer in FIG. 2). .. Further, a sidewall rubber layer 13 exposed on the outer surface of the tire is arranged in the region extending from the sidewall portion 2 to the bead portion 3.

A rim cushion rubber layer 14 is arranged between the bead filler 6 and the sidewall rubber layer 13. The rim cushion rubber layer 14 extends from the side position of the bead filler 6 toward the inner diameter side. That is, it is arranged in a region extending from the position on the inner diameter side of the outer diameter side end portion 6e of the bead filler 6 to the position on the inner diameter side of the bead core 5. The rim cushion rubber layer 14 is arranged so as to cover the winding end portion 4e of the carcass layer 4, the winding end portion 11e of the steel reinforcing layer 11, and the non-metal reinforcing layer 12.

The steel reinforcing layer 11 is arranged adjacent to the carcass layer 4, and the non-metal reinforcing layer 12 is arranged adjacent to the steel reinforcing layer 11. Here, "adjacent" means that the interlayer gauge between the steel reinforcing layer 11 and the carcass layer 4 and the interlayer gauge between the steel reinforcing layer 11 and the non-metal reinforcing layer 12 are 0.2 mm to 2.0 mm. .. The "interlayer gauge" means the distance between the reinforcing bodies, and specifically, the distance between the carcass cord constituting the carcass layer 4 and the steel cord constituting the steel reinforcing layer 11, or the steel reinforcing layer 11 The distance between the steel cord constituting the above and any of the resin film, the organic fiber cord and the organic fiber woven fabric constituting the non-metal reinforcing layer 12.

The non-metal reinforcing layer 12 is made of a non-metal material, and for example, resin or organic fiber can be used. Examples of the resin include a thermoplastic resin and a thermoplastic elastomer composition containing a mixture of the thermoplastic resin and the elastomer. Examples of the organic fiber include nylon, polyester, and rayon. Since such a material can suppress slippage on the surface of rubber, it is suitable as a material for suppressing rubber flow during vulcanization.

The winding end portion 4e of the carcass layer 4 and the winding end portion 11e of the steel reinforcing layer 11 may be covered with rubber edge tapes, respectively. Edge tape is not always necessary, but it is effective from the viewpoint of preventing separation.

As shown in FIG. 3, the higher of the height from the apex 3h of the bead heel of the bead portion 3 to the winding end portion 4e of the carcass layer 4 and the winding end portion 11e of the steel reinforcing layer 11 is the hoisting height. is the PLY _h [mm], the height of the end portion 12e of the outer side in the tire radial direction in the first non-metallic reinforcing layer 12A and the height CHF _h1 [mm] from the bead heel vertex 3h of the bead portion 3. At this time, the hoisting height PLY _h of the carcass layer 4 or the steel reinforcing layer 11 and the height CHF _{h1 of} the first non-metal reinforcing layer 12A satisfy the relationship of PLY _h- 15 ≤ CHF _h1 ≤ PLY _h . In the illustrated example, since the winding end portion 4e of the carcass layer 4 is higher than the winding end portion 11e of the steel reinforcing layer 11, the hoisting height PLY _h is the height of the winding end portion 4e of the carcass layer 4. In the present invention, the winding end portion 11e of the steel reinforcing layer 11 can be made higher than the winding end portion 4e of the carcass layer 4, but in particular, as shown in the figure, the winding end portion 4e of the carcass layer 4 is the first non. It is preferable to raise the metal reinforcing layer 12A at the outer end portion 12e in the tire radial direction and the steel reinforcing layer 11 at the winding end portion 11e in this order.

Further, a line segment connecting the center of the wire F located on the outermost side in the tire width direction and the apex 3h of the bead heel of the bead portion 3 among the plurality of wires constituting the bottom surface of the bead core 5 is defined as a line segment G. .. At this time, the end portion 12e of the first non-metal reinforcing layer 12A on the inner side in the tire radial direction is located in the region on the inner side in the tire width direction with respect to the line segment G. When the apex of the bead heel of the bead portion 3 is not clearly determined, the two curves forming the bead heel of the bead portion 3 are extended, and the intersection of the extension lines is used as the apex of the bead heel.

Further, the first non-metal reinforcing layer 12A is arranged at a distance of 1.5 mm or more from the outer surface of the bead portion 3. The outer surface of the bead portion 3 is the surface of the bead portion 3 in contact with the rim. That is, in the bead portion 3, a surface extending outward in the tire radial direction and a surface extending inward in the tire width direction from the apex 3h of the bead heel.

In the pneumatic tire described above, the bead filler 6 is arranged on the outer periphery of the bead core 5 of each bead portion 3, and the steel reinforcing layer 11 including a plurality of steel cords in each bead portion 3 is a carcass layer 4, the bead core 5 and the bead. The filler 6 is arranged so as to wrap around the filler 6, the first non-metal reinforcing layer 12A is arranged on the outer side of the steel reinforcing layer 11 in the tire width direction, and the higher of the carcass layer 4 and the steel reinforcing layer 11 is the higher winding end portion 4e, 11e. The hoisting height PLY _h [mm] and the height CHF _h1 [mm] of the outer end portion 12e in the tire radial direction in the first non-metal reinforcing layer 12A are PLY _h- 15 ≤ CHF _h1 ≤ PLY _h . By satisfying the relationship, the rubber flow on the side of the bead core 5 is suppressed based on the first non-metal reinforcing layer 12A, so that the rubber thickness from the winding end portion 4e of the carcass layer 4 to the outer surface of the bead portion 3 The tire thickness can be reduced, and further, the thinning of the bead filler 6 and the rubber flow to the bead filler top side due to the addition of the first non-metal reinforcing layer 12A can be suppressed. As a result, the equilibrium carcass line is approached around the bead portion 3, so that the durability of the bead portion 3 can be improved. As described above, since the rubber flow in the bead filler 6 during vulcanization is suppressed, the cost can be suppressed to the same level as that of a pneumatic tire having no non-metal reinforcing layer 12.

Further, since the end portion 12e on the inner side in the tire radial direction of the first non-metal reinforcing layer 12A is located in the region on the inner side in the tire width direction with respect to the line segment G, the side of the bead core 5 in which a violent rubber flow occurs during vulcanization. Since the first non-metal reinforcing layer 12A is arranged on the side, the rubber flow of the rim cushion rubber layer 14 arranged on the side of the bead core 5 can be significantly suppressed. As a result, the rubber flow from the side of the bead core 5 to the winding end portion 4e of the carcass layer 4 can be suppressed, so that the rubber flows closer to the equilibrium carcass line and contributes to the improvement of the durability of the bead portion 3. Further, since the first non-metal reinforcing layer 12A is arranged at a distance of 1.5 mm or more from the outer surface of the bead portion 3, the first non-metal reinforcing layer 12A does not come into direct contact with the rim, so that the bead portion The tension caused by the contact between 3 and the rim flange is relaxed, and the separation from the end portion 12e of the first non-metal reinforcing layer 12A can be suppressed.

On the other hand, in the conventional structure in which an organic fiber reinforcing layer is embedded in the bead portion and the end portion of the organic fiber reinforcing layer on the outer side in the tire radial direction is higher than the winding end portion of the vulcanization layer, the side of the bead filler is lateral. As the rubber thickness at the position increases, the bead filler tends to be crushed in the tire width direction due to the rigidity of the organic fiber reinforcing layer in the region outside the tire radial direction from the winding end of the carcass layer in the bead filler during vulcanization. There is. According to the present invention, it is possible to prevent such an adverse effect on the bead portion.

In the pneumatic tire of the present invention, the higher hoisting height PLY _h of the hoisting end portion 4e of the carcass layer 4 and the hoisting end portion 11e of the steel reinforcing layer 11 is preferably 25 mm to 45 mm, preferably 28 mm to 38 mm. More preferably. By setting the hoisting height PLY _h in this way, the separation from the ends 4e, 11e, 12e of the carcass layer 4, the steel reinforcing layer 11, or the first non-metal reinforcing layer 12A can be effectively suppressed. Can be done.

Here, when the hoisting height PLY _h is less than 25 mm, the end portion 12e of the first non-metal reinforcing layer 12A is excessively close to the rim flange, so that stress is not dispersed and there is a concern that separation may occur. .. On the other hand, when the hoisting height PLY _h exceeds 45 mm, the hoisting ends 4e and 11e of the carcass layer 4 or the steel reinforcing layer 11 are located in a region where the deformation is large during vulcanization, so that the carcass layer 4 or the steel There is a concern that separation may occur from the ends 4e and 11e of the reinforcing layer 11.

Further, the winding end 4e of the carcass layer 4 is higher than the winding end 11e of the steel reinforcing layer 11, and the outer end 12e of the first non-metal reinforcing layer 12A in the tire radial direction and the winding end 4e of the carcass layer 4 The shortest distance L (see FIG. 2) with and from is preferably 2 mm or more. As a result, the stress at the end portion 12e of the first non-metal reinforcing layer 12A can be dispersed, and the separation from the end portion 12e of the first non-metal reinforcing layer 12A can be effectively suppressed. The upper limit of the shortest distance L is determined in relation to the configuration in which the first non-metal reinforcing layer 12A is arranged at a distance of 1.5 mm or more from the outer surface of the bead portion 3. Here, when the shortest distance L is less than 2 mm, the stress at the end portion 12e of the first non-metal reinforcing layer 12A is not dispersed, and there is a concern that separation may occur.

Further, the first non-metal reinforcing layer 12A can be configured as follows. The first non-metal reinforcing layer 12A may be composed of a plain woven fabric having a warp and weft fiber structure of 200/1 [dtex / piece] to 1000/1 [dtex / piece]. The plain-woven first non-metal reinforcing layer 12A is woven by crossing warp threads and weft threads one by one, and has no fiber directionality. By constructing the first non-metal reinforcing layer 12A in this way, it is possible to suppress the rubber flow regardless of the fiber direction of the plain woven fabric. Further, the thickness of the first non-metal reinforcing layer 12A can be reduced.

Here, when the fiber structure of the warp and weft is less than 200/1 [dtex / piece], the rubber flow cannot be effectively suppressed, and the fiber structure of the warp and weft is 1000/1 [dtex / piece]. This] is not preferable because it causes an excessive increase in cost.

Alternatively, the first non-metal reinforcing layer 12A may be composed of a bamboo blind fabric having a fiber structure of 800/2 [dtex / piece] to 1500/2 [dtex / piece]. The first non-metal reinforcing layer 12A woven with bamboo blinds is made by arranging and knitting fiber cords in one direction, has the directionality of the fiber cords, and follows the elongation deformation during tire manufacturing. By constructing the first non-metal reinforcing layer 12A in this way, it is possible to reduce the rigidity step with the rubber at the end portion 12e of the first non-metal reinforcing layer 12A as compared with the case of the plain woven fabric. , The separation from the end portion 12e of the first non-metal reinforcing layer 12A can be effectively suppressed.

Here, when the fiber structure of the fiber cord is less than 800/2 [dtex / piece], the rubber flow cannot be effectively suppressed, and the fiber structure of the fiber cord is 1500/2 [dtex / piece]. If it exceeds, it causes an excessive increase in cost, which is not preferable.

When the first non-metal reinforcing layer 12A is composed of a bamboo blind fabric as described above, the driving density of the fiber cords of the bamboo blind fabric may be 10 lines / 50 mm to 40 lines / 50 mm. Thereby, the separation from the end portion 12e of the first non-metal reinforcing layer 12A can be effectively suppressed.

Here, when the driving density of the fiber cord is less than 10 fibers / 50 mm, the rubber flow cannot be effectively suppressed, and when the driving density of the fiber cord exceeds 40 fibers / 50 mm, an excessive cost is required. It is not preferable because it causes an increase in.

Further, the inclination angle θ (see FIG. 4) of the fiber cord forming the bamboo blind fabric with respect to the tire circumferential direction is set to 15 ° to 70 °, and the orientation direction of the fiber cord of the bamboo blind fabric is opposite to that of the steel cord of the steel reinforcing layer 11. It is good to do. As shown in FIG. 4, the fiber cord of the first non-metal reinforcing layer 12A and the steel cord of the steel reinforcing layer 11 are oriented in opposite directions and intersect with each other. By constructing the bamboo blind fabric in this way, the rubber flow can be effectively suppressed.

Here, when the inclination angle is less than 15 °, the rubber flow cannot be effectively suppressed, and when the inclination angle exceeds 70 °, the fiber cord of the bamboo blind fabric shares an excessive tension. Therefore, there is a concern that separation may occur from the end portion 12e of the first non-metal reinforcing layer 12A.

FIG. 5 shows a modified example of the bead portion. In FIG. 5, the first non-metal reinforcing layer 12A is bent outward in the tire width direction at the middle portion in the extending direction, and the end portion 12e on the outer side in the tire radial direction is in contact with the sidewall rubber layer 13. In the illustrated example, the first non-metal reinforcing layer 12A is bent at a portion inside the winding end portion 11e of the steel reinforcing layer 11 in the tire radial direction, but the present invention is not limited to this.

In FIG. 5, the rim cushion rubber layer 14 extends from the lateral position of the bead core 5 toward the inner diameter side. That is, it is arranged in a region extending from the end portion 12e on the outer side in the tire radial direction of the first non-metal reinforcing layer 12A to the position on the inner diameter side of the bead core 5. Between the bead filler 6 and the sidewall rubber layer 13, the crack suppressing layer 15 is the tire diameter of the winding end portion 4e of the carcass layer 4, the winding end portion 11e of the steel reinforcing layer 11, and the first non-metal reinforcing layer 12A. It is arranged so as to cover the end portion 12e on the outer side of the direction. The crack suppressing layer 15 is arranged in a region extending from a position on the inner diameter side of the bead filler 6 to a position on the inner diameter side of the end portion 11e of the steel reinforcing layer 11.

As the physical properties of the rubber constituting the crack suppressing layer 15, it is preferable that the 100% modulus Kc _M100 is 4.5 MPa to 10.0 MPa and the breaking elongation Kc _EB is 300% or more. By using the rubber having such physical properties for the crack suppressing layer 15, the separation from the end portions 4e and 12e of the carcass layer 4 or the first non-metal reinforcing layer 12A can be effectively suppressed.

Here, when the 100% modulus Kc _M100 is 4.5 MPa, stress concentration at the end portion 12e of the first non-metal reinforcing layer 12A is promoted, and there is a concern that separation may occur at the end portion 12e. If the 100% modulus Kc _M100 exceeds 10.0 MPa, it is difficult to set the elongation at break Kc _EB to 300% or more, which is not preferable. Further, when the breaking elongation Kc _EB is less than 300%, it becomes difficult to suppress the separation from the end portions 4e and 12e of the carcass layer 4 or the first non-metal reinforcing layer 12A.

In FIG. 5, a line segment connecting the center of the wire I located on the innermost side in the tire radial direction and the bead toe 3t of the bead portion 3 among the plurality of wires constituting the bead core 5 is defined as a line segment J. A region (a region surrounded by a single point chain line in the figure) in which the shortest distance from the line segment J in the direction perpendicular to J is −8 mm to 8 mm is defined as region X. At this time, the end portion 12e on the inner side in the tire radial direction of the first non-metal reinforcing layer 12A is arranged in the region X. The region X is a region inside the tire width direction (left side in the figure) from the line segment J when the shortest distance is a positive value, and outside the tire width direction from the line segment J when the shortest distance is a negative value (FIG. The area on the right side of).

In the pneumatic tire described above, the tire radial inner end 12e of the first non-metal reinforcing layer 12A is arranged in the region X, that is, the first non-metal reinforcing layer 12A is arranged below the bead core 5. Therefore, the compressive strain of the rubber at the lower part of the bead core 5 increases during vulcanization, and the position of the bead core 5 can be moved closer to the bead toe 3t side. As a result, it contributes to the realization of the balanced carcass line around the bead portion 3, which leads to the improvement of the durability of the bead portion 3.

Here, when the shortest distance from the line segment J is less than -8 mm, the end portion 12e on the inner side in the tire radial direction of the first non-metal reinforcing layer 12A is arranged in a region where contact with the rim is severe. There is a concern that separation may occur from the end 12e. On the other hand, when the shortest distance from the line segment J exceeds 8 mm, the end portion 12e on the inner side in the tire radial direction of the first non-metal reinforcing layer 12A is arranged in a region where the effect of suppressing the rubber flow cannot be expected. This is not preferable because it causes an excessive increase in cost.

FIG. 6 shows another modified example of the bead portion. As shown in FIG. 6, the non-metal reinforcing layer 12 includes the first non-metal reinforcing layer 12A located inside in the tire width direction at the lateral position of the winding end portion 11e of the steel reinforcing layer 11 and outside in the tire width direction. It has a two-layer structure composed of a second non-metal reinforcing layer 12B located. Further, the winding end portion 4e of the carcass layer 4 is higher than the winding end portion 11e of the steel reinforcing layer 11. That is, the hoisting height PLY _h is the height of the hoisting end portion 4e of the carcass layer 4. The hoisting height PLY _h [mm] of the winding end 4e of the carcass layer 4 and the height CHF _h2 [mm] of the outer end 12e in the tire radial direction in the second non-metal reinforcing layer 12B are PLY _h. The relationship of -23 ≤ CHF _h2 ≤ PLY _h- 8 is satisfied. The hoisting height PLY _h of the carcass layer 4 and the height CHF _{h1 of} the first non-metal reinforcing layer 12A satisfy the relationship of PLY _h -15 ≤ CHF _h1 ≤ PLY _h .

Further, in FIG. 6, the tire radial inner end 12e in the second non-metal reinforcing layer 12B is separated from the tire radial inner end 12e in the first non-metal reinforcing layer 12A by 4 mm or more. In particular, when separating the inner end portion 12e of the first non-metal reinforcing layer 12A and the second non-metal reinforcing layer 12B in the tire radial direction from each other, the end portion 12e of the second non-metal reinforcing layer 12B as shown in the figure. Is preferably separated inward in the tire width direction from the end portion 12e of the first non-metal reinforcing layer 12A. Further, the second non-metal reinforcing layer 12B is arranged at a distance of 1.5 mm or more from the outer surface of the bead portion 3 like the first non-metal reinforcing layer 12A.

In the above-mentioned pneumatic tire, a two-layer non-metal reinforcing layer 12 composed of a first non-metal reinforcing layer 12A and a second non-metal reinforcing layer 12B is adopted, and the hoisting height of the winding end portion 4e of the carcass layer 4 is adopted. The PLY _h and the height CHF _h2 of the outer end portion 12e in the tire radial direction in the second non-metal reinforcing layer 12B satisfy the relationship of PLY _h- 23 ≤ CHF _h2 ≤ PLY _h- 8, and the second non-metal. The tire radial inner end 12e of the reinforcing layer 12B is separated from the tire radial inner end 12e of the first non-metal reinforcing layer 12A by 4 mm or more, and the second non-metal reinforcing layer 12B is of the bead portion 3. Since it is arranged at a distance of 1.5 mm or more from the outer surface, the durability of the bead portion 3 can be effectively improved.

Further, it is preferable to arrange each end portion 12e of the first non-metal reinforcing layer 12A and the second non-metal reinforcing layer 12B on the inner side in the tire radial direction in the above-mentioned region X. It is desirable that the second non-metal reinforcing layer 12B has a fiber structure having the same fiber cord as the first non-metal reinforcing layer 12A.

With a tire size of 275 / 70R22.5, a tread portion, a pair of sidewall portions, and a pair of bead portions are provided, and a carcass layer containing a plurality of steel cords is mounted between the pair of bead portions. In a pneumatic tire having a structure in which the tire is wound around the bead core of each bead portion from the inside to the outside of the tire, only the structure of the bead portion is different in Conventional Examples 1 and 2, Comparative Examples 1 to 3 and Examples 1 to 1. I made 21 tires.

In the tires of Conventional Examples 1, 2, Comparative Examples 1 to 3, and Examples 1 to 21, the height of the winding end of the carcass layer, the height of the winding end of the steel reinforcing layer, and the height of the winding end. Large / small relationship (winding height PLY _h ), number of layers of non-metal reinforcing layer, height CHF _h1 of first non-metal reinforcing layer, position of radial inner end of first non-metal reinforcing layer, first The position of the non-metal reinforcing layer with respect to the line G, the distance to the outer surface of the bead portion of the first non-metal reinforcing layer, the shortest distance L, and the radial inner end of the first non-metal reinforcing layer from the line J. Distance, modulus Kc _M100 of crack suppression layer, break elongation Kc _EB of crack suppression layer, type of fabric forming the first non-metal reinforcing layer, fiber structure of warp and weft of plain fabric, fiber structure of fiber cord of leopard fabric , The driving density of the fiber cord of the woven fabric, the inclination angle of the fiber cord of the woven fabric, the orientation direction of the fiber cord of the woven fabric, the height of the second non-metal reinforcing layer CHF _h2 , the first and second non-metal reinforcement The separation distance between the layers and the distance to the outer surface of the bead portion of the second non-metal reinforcing layer were set as shown in Tables 1 and 2.

In Tables 1 and 2, when the height relationship of the winding end is "carcass", the winding end of the carcass layer is higher than the winding end of the steel reinforcing layer, and the winding end of the carcass layer is higher. height hoisting height PLY _h next to, in the case of "steel", up end portion of the steel reinforcing layer is higher than the winding-up end of the carcass layer, the height of the winding end portion of the carcass layer is the hoisting height It becomes PLY _h . The "position of the radial inner end of the first non-metal reinforcing layer" indicates the distance between the inner end in the tire radial direction and the apex of the bead heel of the bead portion. When the position of the first non-metal reinforcing layer with respect to the line segment G is "inside", the inner end of the first non-metal reinforcing layer in the tire radial direction is located in the region inside the line segment G in the tire width direction. , "Outside" means that the end is located in a region outside the line segment G in the tire width direction. The orientation direction of the fiber cord of the bamboo blind fabric indicates the direction of the steel reinforcing layer with respect to the steel cord.

For these test tires, the durability and cost of the bead portion were evaluated by the following test method, and the results are shown in Tables 1 and 2.

Durability of bead part:
Each test tire is mounted on the specified rim of JATTA, set to 75% of the specified air pressure of JATTA, loaded 1.4 times the specified load of JATTA, and subjected to the drum test under the conditions of running speed 49 km / h and mileage. A running test was conducted. After traveling 40,000 km, the test tire was cut along the tire meridian at eight points at equal intervals in the tire circumferential direction, and the winding end of the carcass layer and the winding end of the carcass layer at eight cut surfaces (16 points in total) of both bead parts. The length of the crack in the cross-sectional direction starting from each end of the non-metal reinforcing layer was measured. The evaluation result is shown by an index with Conventional Example 2 as 100 using the reciprocal of the measured value. The larger the index value, the better the durability of the bead portion.

cost:
The production cost of the reinforcing member in the bead part of each test tire was estimated. The evaluation result is shown by an index with Conventional Example 2 as 100 using the reciprocal of the estimated value. The larger the index value, the lower the cost and the better.

As can be seen from Tables 1 and 2, the tires of Examples 1 to 21 have improved durability and cost of the bead portion as compared with Conventional Example 2.

On the other hand, in each of the tires of Comparative Examples 1 and 2, since the inner end portion of the non-metal reinforcing layer in the tire radial direction is located outside the line segment G in the tire width direction, the durability and cost of the bead portion are improved. A sufficient improvement effect could not be obtained. Further, in the tire of Comparative Example 3, since the shortest distance L between the outer end portion of the non-metal reinforcing layer in the tire radial direction and the carcass layer was set to be large, the durability of the bead portion deteriorated.

1 tread part 2 sidewall part 3 bead part 4 carcass layer 5 bead core 6 bead filler 11 steel reinforcement layer 12 non-metal reinforcement layer 12A first non-metal reinforcement layer 12B second non-metal reinforcement layer 13 sidewall rubber layer 14 rim Cushion rubber layer 15 Crack suppression layer

Claims (10)

A tread portion extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and a pair of bead portions arranged inside the tire radial direction of these sidewall portions. In a pneumatic tire having a structure in which a carcass layer containing a plurality of steel cords is mounted between the pair of bead portions, and the carcass layer is wound around the bead core of each bead portion from the inside to the outside of the tire. ,
A bead filler is arranged on the outer periphery of the bead core of each bead portion, and a steel reinforcing layer containing a plurality of steel cords is arranged in each bead portion so as to wrap the carcass layer, the bead core, and the bead filler. The first non-metal reinforcement layer is placed on the outside of the layer in the tire width direction,
The hoisting height PLY _h [mm] of the carcass layer and the steel reinforcing layer, whichever has the higher winding end, and the height of the outer end in the tire radial direction of the first non-metal reinforcing layer CHF _h1 [ mm] satisfies the relationship of PLY _h -15 ≤ CHF _h1 ≤ PLY _h .
When the line segment connecting the center of the wire F located on the outermost side in the tire width direction and the apex of the bead heel of the bead portion among the plurality of wires constituting the bottom surface of the bead core is defined as the line segment G, the above The inner end of the first non-metal reinforcing layer in the tire radial direction is located in the region inside the tire width direction with respect to the line segment G.
A pneumatic tire, wherein the first non-metal reinforcing layer is arranged at a distance of 1.5 mm or more from the outer surface of the bead portion. The pneumatic tire according to claim 1, wherein the hoisting height PLY _{h of the} carcass layer and the steel reinforcing layer, whichever has the higher hoisting end, is 25 mm to 45 mm. The winding end of the carcass layer is higher than the winding end of the steel reinforcing layer, and the shortest distance L between the tire radial outer end of the first non-metal reinforcing layer and the winding end of the carcass layer is The pneumatic tire according to claim 1 or 2, wherein the tire is 2 mm or more. From the line segment J in the direction perpendicular to the line segment J connecting the center of the wire located on the innermost side in the tire radial direction and the bead toe of the bead portion among the plurality of wire wires constituting the bead core. Claim 1 is characterized in that the inner end portion of the first non-metal reinforcing layer in the tire radial direction is arranged in the region X, where the region where the shortest distance is −8 mm to 8 mm is defined as the region X. Pneumatic tire according to any one of ~ 3. The crack suppressing layer located between the sidewall rubber layer exposed on the outer surface of the tire from the sidewall portion to the bead portion and the bead filler is the winding end portion of the carcass layer, the winding end portion of the steel reinforcing layer, and the winding end portion. The first non-metal reinforcing layer is arranged so as to cover the outer end of the tire radial direction, and the 100% modulus Kc _M100 of the crack suppressing layer is 4.5 MPa to 10.0 MPa, and the crack suppressing layer is broken. The pneumatic tire according to any one of claims 1 to 4, wherein the elongation Kc _EB is 300% or more. The first non-metal reinforcing layer according to claim 1 to 5, wherein the warp and weft fibers are made of a plain woven fabric having a fiber structure of 200/1 [dtex / piece] to 1000/1 [dtex / piece]. Pneumatic tires listed in either. Any of claims 1 to 5, wherein the first non-metal reinforcing layer is made of a bamboo blind fabric having a fiber cord having a fiber structure of 800/2 [dtex / piece] to 1500/2 [dtex / piece]. Pneumatic tires listed in Crab. The pneumatic tire according to any one of claims 7, wherein the fiber cords of the bamboo blind fabric have a driving density of 10/50 mm to 40/50 mm. The fiber cord forming the bamboo blind fabric has an inclination angle of 15 ° to 70 ° with respect to the tire circumferential direction, and the orientation direction of the fiber cord of the bamboo blind fabric is opposite to that of the steel cord of the steel reinforcing layer. The pneumatic tire according to claim 7 or 8. A second non-metal reinforcing layer is adjacent to the outside of the first non-metal reinforcing layer in the tire width direction on the side of the winding end of the steel reinforcing layer, and the winding end of the carcass layer is the steel. The hoisting height PLY _h of the hoisting end of the carcass layer and the height CHF _h2 of the outer end in the tire radial direction of the second non-metal reinforcing layer, which are higher than the hoisting end of the reinforcing layer, are PLY _h. Satisfying the relationship of -23 ≤ CHF _h2 ≤ PLY _h- 8, the inner end of the second non-metal reinforcing layer in the tire radial direction is 4 mm from the inner end of the first non-metal reinforcing layer in the tire radial direction. The air-filled according to any one of claims 1 to 9, wherein the second non-metal reinforcing layer is arranged at a distance of 1.5 mm or more from the outer surface of the bead portion. tire.

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