JP7011461B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire.

In pneumatic radial tires, a cord reinforcing layer including a cord such as a nylon cord or a steel cord may be provided along the winding portion of the carcass ply in order to improve the durability of the bead portion. By providing a cord reinforcing layer around the winding part of the carcass ply to reinforce it, the distortion of the winding end of the carcass ply can be dispersed, but the rigidity of the cord reinforcing layer is on the rubber arranged around the bead part. Since it is extremely high, stress strain is concentrated on the end of the cord reinforcing layer, and the durability of the bead portion tends to decrease.

Therefore, in Patent Document 1 below, in a pneumatic tire in which the carcass ply has a laminated ply structure of two or more layers at the position of the bead portion, the carcass ply is laminated so that the ply cords intersect each other at the position of the laminated ply structure. Has been proposed.

Japanese Unexamined Patent Publication No. 11-310007

In Patent Document 1, not only the ply cords intersect each other on the outer side of the bead filler in the tire width direction, but also the winding portion of the carcass ply overlaps with the main body portion of the carcass ply provided between the pair of left and right bead portions. The ply codes are crossed. At the position where the winding part of the carcass ply overlaps with the main body part, the number of laminated carcass plies is larger than at other positions and the ply cords also intersect, so the tire rigidity is locally increased and the ride quality is improved. Is impaired.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pneumatic tire capable of improving the durability of a bead portion without locally increasing the tire rigidity.

The pneumatic tire of the present invention has a pair of bead portions having a bead core, a bead filler arranged outside the bead core in the meridian direction, a main body portion provided between the pair of bead portions, and the main body. The carcass ply comprises a carcass ply having a winding portion extending from the portion and folded from the inside to the outside in the tire width direction around the bead core and wound outward in the radial direction of the tire along the bead filler, and the carcass ply is in the meridian direction. A first carcass ply including a first ply cord arranged along the meridian, and a second carcass ply including a second ply cord arranged along the meridian direction and arranged on the outer surface side of the first carcass ply. The winding portion of the first carcass ply has a first inclined region in which the first ply cord is arranged along a direction inclined with respect to the meridian direction, and the first inclined region outward in the tire radial direction. A first meridian region in which the first ply cord is arranged along the meridian direction is provided, and the winding portion of the second carcass ply reverses the second ply cord to the first inclined region with respect to the meridian direction. It is provided with a second inclined region arranged along the direction of inclination and a second meridian region in which the second ply cord is arranged along the meridian direction outside the tire radial direction of the second inclined region. The boundary between the first inclined region and the first meridian region and the boundary between the second inclined region and the second meridian region are located inward in the tire radial direction from the tip of the bead filler, and the first inclined region and the first meridian are located. The boundary with the region and the boundary between the second inclined region and the second meridian region are arranged so as to be offset in the tire radial direction, and the tip of the winding portion of the first carcass ply is the tip of the second carcass ply. It is located on the outer side in the tire radial direction from the tip of the winding portion and is in contact with the main body portion of the second carcass ply.

In a preferred embodiment of the present invention, the first ply cord in the first inclined region and the second ply cord in the second inclined region may have a smaller inclination angle with respect to the meridian direction toward the outer side in the tire radial direction. ..

In another preferred embodiment of the present invention, the tire may be a tire for a light truck.

According to the present invention, the durability of the bead portion can be improved without locally increasing the tire rigidity.

A tire meridian half cross section showing a pneumatic tire of the present embodiment. FIG. 1 is a view of the bead core, bead filler, and carcass ply of the pneumatic tire of FIG. 1 as viewed from the tire side surface.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a tire meridional cross-sectional view showing an example of a pneumatic tire (hereinafter referred to as “tire”) 10 of the first embodiment, and shows a half cross section in a state of being mounted on a rim flange 1 of a specified rim. ..

In the present specification, the tire width direction is a direction parallel to the tire rotation axis and is synonymous with the tire axis direction. show. The tire radial direction is a direction perpendicular to the tire rotation axis, and is indicated by reference numeral Z in the figure, and the inside and outside of the tire radial direction are indicated by reference numerals Z1 and Z2, respectively. The tire meridian direction is a direction along the tire cross-sectional profile when cut at a surface including the tire rotation axis, and is indicated by reference numeral MD in the figure. The tire circumferential direction is a direction on the circumference centered on the tire rotation axis, and is indicated by reference numeral R in the figure.

The tire 10 of the present embodiment is a tire for a small truck such as an SUV car or a pickup truck, and has a pair of left and right bead portions 11 provided on both sides in the tire width direction Y and a pair extending outward from the bead portions 11 in the tire radial direction. The sidewall portion 15 is provided with a tread portion 16 provided between the sidewall portions 15 so as to connect the radial outer ends of the left and right sidewall portions 15 to each other.

In the bead portion 11, an annular bead core 12 made of a convergent body obtained by laminating and winding rubber-coated bead wires and a rubber bead filler 13 arranged on the tire radial outer side Z2 of the bead core 12 are integrated. An annular bead member 14 is embedded. The bead filler 13 is made of hard rubber and has a triangular cross-section narrower toward the tip side extending from the maximum tire width position to the outer Z2 in the tire radial direction.

Inside the tire 10, two toroid-shaped carcass plies 20A and 20B are provided so as to be bridged between the pair of bead portions 11. The two carcass plies 20A and 20B are composed of two pieces, a first carcass ply 20A on the inner surface side of the tire and a second carcass ply 20B provided on the outer side thereof. The two carcass plies 20A and 20B reach the bead portion 11 from the tread portion 16 via the sidewall portions 15 on both sides, and are wound up and locked around the bead core 12 in the bead portion 11. In this example, the case where two carcass plies 20A and 20B are provided will be described, but three or more carcass plies may be provided inside the tire 10.

A belt 30 is provided on the outer surface side of the tire of the second carcass ply 20B in the tread portion 16. The belt 30 has a plurality of cords (for example, steel cords) coated with rubber, and the tread portion 16 is reinforced by the outer circumferences of the two carcass plies 20A and 20B. A tread rubber 32 having an outer surface as a ground contact surface is provided on the outer side of the belt 30 in the radial direction of the tire.

An inner liner 34 as an air-resistant rubber layer constituting the inner peripheral surface of the tire 10 is provided on the inner surface side of the tire of the first carcass ply 20A. The sidewall portion 15 is provided with sidewall rubbers 33 constituting the outer wall surface of the tire 10 on both sides of the first carcass ply 20A in the tire width direction.

A rim strip 40 is provided on the outer side Y2 of the bead portion 11 in the tire width direction. The upper part of the rim strip 40 is in contact with the lower part of the sidewall rubber 33. The lower portion of the rim strip 40 enters the tire radial inner side Z1 from the bead core 12 and is in contact with the inner liner 34. The rim strip 40 constitutes the outer surface of the tire around the bead portion 11, and the tire 10 comes into contact with the rim flange 1 when the rim is assembled.

In the tire 10 having such a configuration, the two carcass plies 20A and 20B extend from the main body portions 21A and 21B provided between the pair of bead portions 11 and forming the tire skeleton and the main body portions 21A and 21B. It has winding portions 22A and 22B that are folded back from the inside to the outside in the tire width direction around the bead portion 11 so as to wrap the bead core 12 and the bead filler 13.

The winding portions 22A and 22B of the carcass ply 20A and 20B extend to the outer side Z2 in the tire radial direction along the outer side surface in the tire width direction of the bead core 12 and the bead filler 13. The tips of the winding portions 22A and 22B (that is, the winding ends 22AE and 22BE) extend beyond the upper end (that is, the outer end in the tire radial direction) 13A of the bead filler 13 and terminate in the sidewall portion 15.

The winding portion 22B of the second carcass ply 20B is in contact with the main body portion 21B at the tire radial outer side Z2 of the bead filler 13. The winding portion 22A of the first carcass ply 20A covers the outside of the winding portion 22B of the second carcass ply 20B, and is formed to have a higher winding position (that is, outward in the tire radial direction) than the winding portion 22B of the second carcass ply 20B. Has been done. The vicinity of the winding end 22AE of the first carcass ply 20A is in contact with the main body portion 21B of the second carcass ply 20B.

As shown in FIG. 2, the first carcass ply 20A includes a plurality of first ply cords 23A provided at intervals in the tire circumferential direction R, and a coated rubber 24A covering the plurality of first ply cords 23A. Be prepared. Further, the second carcass ply 20B also has a plurality of second ply cords 23B provided at intervals in the tire circumferential direction R and a coated rubber 24B covering the plurality of second ply cords 23B, similarly to the first carcass ply 20A. And prepare. As the first ply cord 23A and the second ply cord 23B, a metal cord such as a steel cord, an organic fiber cord such as polyester or nylon, or the like is used.

A plurality of first ply cords 23A of the first carcass ply 20A are arranged at intervals in the tire circumferential direction R. The first ply cord 23A extends along the meridian direction (direction substantially orthogonal to the tire circumferential direction R) MD in the main body portion 21A, and extends radially outward from the tire radial inner end portion of the winding portion 22A. It extends along a direction inclined with respect to the MD in the meridian direction, bends at a position inside the tire radial direction from the tip 13A of the bead filler 13, and extends along the MD in the meridian direction.

As a result, the winding portion 22A of the first ply cord 23A is provided with a first inclined region Q1 in which the first ply cord 23A is arranged along the direction of inclination with respect to the meridian direction MD, and is provided inside the tire radial direction. A first meridian region P1 in which the first ply cord 23A is arranged along the meridian direction MD is provided on the tire radial outer side Z2 of the one inclined region Q1. The boundary S1 between the first inclined region Q1 and the first meridian region P1 is arranged on the inner side Z1 in the tire radial direction from the tip 13A of the bead filler 13.

A plurality of second ply cords 23B of the second carcass ply 20B are arranged at intervals in the tire circumferential direction R. The second ply cord 23B extends along the meridian direction MD in the main body portion 21B, and extends outward from the tire radial inner end portion of the winding portion 22B to the first inclined region Q1 with respect to the meridian direction MD. It extends along a direction that inclines in the opposite direction, bends at a position inside the tire radial direction from the tip 13A of the bead filler 13, and extends along the meridian direction MD.

As a result, the winding portion 22B of the second ply cord 23B has a second inclined region Q2 in which the second ply cord 23B is arranged along a direction in which the second ply cord 23B is inclined in the direction opposite to the first inclined region Q1 with respect to the meridian direction MD. A second meridian region P2 is provided inside the tire radial direction and has a second ply cord 23B arranged along the meridian direction MD in the tire radial outer Z2 of the second inclined region Q2. The boundary S2 between the second inclined region Q2 and the second meridian region P2 is arranged on the inner side Z1 in the tire radial direction from the tip 13A of the bead filler 13.

The first inclined region Q1 provided in the winding portion 22A of the first carcass ply 20A and the second inclined region Q2 provided in the winding portion 22B of the second carcass ply 20B are the tire side surfaces as shown in FIG. Visually, the ply cords 23A and the ply cords 23B are overlapped so as to intersect each other in a mesh pattern.

In the present embodiment, the inclined regions Q1 and Q2 of the two carcass plies 20A and 20B are arranged on the tire radial inner side Z1 from the tip 13A of the bead filler 13, and the meridian on the tire radial outer side Z2 from the tip 13A of the bead filler 13. Areas P1 and P2 are arranged. Therefore, the ply cords 23A and 23B intersect each other in a mesh pattern on the outer side Y2 of the bead filler 13 in the tire width direction, but do not intersect on the outer side Z2 of the bead filler 13 in the tire radial direction, and the winding portions of the carcass ply 20A and 20B. Of the 22A and 22B, the ply cords 23A and 23B are arranged substantially in parallel with each other at positions in contact with the main body portions 21A and 21B without intersecting each other in a mesh pattern.

The distance between the ply cords 23A and 23B provided in the first carcass ply 20A and the second carcass ply 20B, the tilt angle of the ply cord 23A in the first tilt region Q1, and the tilt angle of the ply cord 23B in the second tilt region Q2 are Although not particularly limited, for example, the distance between the ply codes 23A and 23B can be 0.2 to 1.2 mm in the tire circumferential direction R, and the first ply code 23A with respect to the meridional direction MD in the first inclination region Q1. The tilt angle can be 15 to 50 °, and the tilt angle of the second ply cord 23B with respect to the meridional direction MD in the second tilt region Q2 can be 15 to 50 °.

The boundary S1 between the first inclined region Q1 and the first meridian region P1 and the boundary S2 between the second inclined region Q2 and the second meridian region P2 are 85% or less of the height H of the bead filler 13 (tire). It is preferably within the range of the radial position).

In the present specification, the distance and the inclination angle of the first ply cord 23A and the second ply cord 23B are values measured in a free state before assembling the pneumatic tire to the rim.

In the tire 10 of the present embodiment, the first ply cord 23A and the second ply cord 23B form a mesh structure on the outer side Y2 of the bead filler 13 in the tire width direction in which a large strain is likely to be concentrated when the tire is deformed. The ply 20A and the second carcass ply 20B can be significantly made highly rigid, and the durability around the bead portion 11 can be improved.

Moreover, in the present embodiment, the ply cords 23A and 23B do not intersect at the tire radial outer side Z2 from the bead filler 13, and come into contact with the main body portions 21A and 21B of the winding portions 22A and 22B of the carcass ply 20A and 20B. Since the ply cords 23A and 23B are arranged substantially in parallel at the positions without intersecting each other in a mesh pattern, the tire rigidity does not locally increase in the sidewall portion 15 and the ride comfort is not impaired.

The above embodiments are presented as examples and are not intended to limit the scope of the invention. This novel embodiment can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention.

For example, in the above embodiment, the inclination angle of the meridian MD of the ply codes 23A and 23B in the first inclination region Q1 and the second inclination region Q2 becomes smaller toward the tire radial outer Z2 (that is, the meridian). It may change (to approach the direction MD).

By changing the inclination angles of the ply cords 23A and 23B in the first inclination region Q1 and the second inclination region Q2 in this way, the tire rigidity of the bead filler 13 at the outer side Y2 in the tire width direction is increased to the outer side Z2 in the tire radial direction. It can be gradually reduced according to. As a result, the strain generated when the tire is deformed can be dispersed, and the durability around the bead portion 11 can be improved.

Further, in the present embodiment, the boundary S1 between the first inclined region Q1 and the first meridian region P1 and the boundary S2 between the second inclined region Q2 and the second meridian region P2 are arranged at the same positions in the tire radial direction Z. However, it may be arranged so as to be offset in the tire radial direction Z.
By arranging the boundary S1 and the boundary S2 so as to be offset in the tire radial direction Z in this way, the tire rigidity of the bead filler 13 on the outer side Y2 in the tire width direction can be gradually reduced to the outer side Z2 in the tire radial direction. As a result, the strain generated when the tire is deformed can be dispersed, and the durability around the bead portion 11 can be improved.

Although the tires for light trucks have been described in the above embodiment, the present invention can be used for various pneumatic tires, and preferably small trucks such as SUVs and pickup trucks that require high durability in the bead portion. It can be applied to tires for heavy loads and heavy load tires for large vehicles such as trucks and buses.

10 ... tire, 11 ... bead part, 12 ... bead core, 13 ... bead filler, 14 ... bead member, 15 ... sidewall part, 16 ... tread part, 20A ... first carcass ply, 20B ... second carcass ply, 21A ... Main body, 21B ... Main body, 22A ... Winding part, 22AE ... Winding end, 22B ... Winding part, 22BE ... Winding end, 23A ... Ply cord, 23B ... Ply cord, 24A ... Coated rubber, 24B ... Coated rubber, P1 ... 1st meridian region, P2 ... 2nd meridian region, Q1 ... 1st inclined region, Q2 ... 2nd inclined region

Claims (3)

A pair of bead portions having a bead core and a bead filler arranged on the outer side of the bead core in the tire radial direction.
A main body portion provided between the pair of the bead portions, a winding extending from the main body portion, being folded back from the inside to the outside in the tire width direction around the bead core, and being wound outward in the tire radial direction along the bead filler. Equipped with a carcass ply that has a part
The carcass ply includes a first carcass ply including a first ply cord arranged along the meridian direction and a second ply cord arranged along the meridian direction, and is arranged on the outer surface side of the first carcass ply. With a second carcass ply,
The winding portion of the first carcass ply has a first inclined region in which the first ply cord is arranged along a direction inclined with respect to the meridian direction, and the first inclined region outside the tire radial direction. It has a first meridian region with one ply code arranged along the meridian direction.
The winding portion of the second carcass ply has a second inclined region in which the second ply cord is arranged along a direction in which the second ply cord is inclined in the direction opposite to the first inclined region with respect to the meridian direction, and the second inclined region. A second meridian region in which the second ply cord is arranged along the meridian direction is provided outside the tire radial direction, and the second ply cord is inclined so as to intersect the first ply cord in a side view. The region overlaps with the first inclined region,
The boundary between the first inclined region and the first meridian region and the boundary between the second inclined region and the second meridian region are located inside the tire radial direction from the tip of the bead filler .
The boundary between the first inclined region and the first meridian region and the boundary between the second inclined region and the second meridian region are arranged so as to be offset in the tire radial direction.
A pneumatic tire in which the tip of the winding portion of the first carcass ply is located outside the tip of the winding portion of the second carcass ply in the radial direction of the tire and is in contact with the main body portion of the second carcass ply. The pneumatic tire according to claim 1, wherein the first ply cord in the first inclined region and the second ply cord in the second inclined region have a smaller inclination angle with respect to the meridian direction toward the outside in the tire radial direction. The pneumatic tire according to claim 1 or 2, which is a tire for a light truck.

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