JP2020121687A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire that can be improved in rim sliding resistance and bead durability while securing rim assemblability.SOLUTION: A bead part 20 is provided with a bead core 30 having a core outer part 31 formed by winding a bead wire 35 around the core outer part and a reinforcement member 40 which is arranged at inside in a tire radial direction of the core outer part 31, whose inner peripheral surface 45 is curved in a direction in which the surface protrudes to outside in the tire radial direction. In the bead core 30, a relation between a height H and a width W is in a range of 0.5≤(W/H)≤1.5, and a relation between the height H of the bead core 30 and a height hr of the reinforcement member 40 is in a range of 0.05≤(hr/H)≤0.5. A relation between a thickness t of the reinforcement member 40 and a width wr of the reinforcement member 40 is in a range of 3≤(wr/t)≤25, and a relation between a dent amount d of the reinforcement member 40 and the thickness t of the reinforcement member 40 is in a range of 0.2≤(d/t)≤1.2, and a relation of a width wb of the core outer part 31 and the width wr of the reinforcement member 40 is in a range of 0.9≤(wr/wb)≤1.1.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pneumatic tire.

A pneumatic tire is mounted on a rim wheel by fitting a bead portion having a bead core, which is an annular member formed by winding a bead wire in the tire circumferential direction and bundling the bead wire, to the rim of the rim wheel. In addition, in recent years, there are some bead cores that are configured using members other than bead wires. For example, a bead core included in a pneumatic tire described in Patent Document 1 is formed by winding a belt-shaped body in an overlapping manner, and a bead core has a radially inwardly projecting radially inward protruding portion at a center portion in a width direction. A projecting portion is formed. Further, Patent Document 2 describes a bead wire formed by depositing a curved ribbon. Further, Patent Document 3 describes a bead core having a laminated structure of a wire layer formed by winding a wire in a plurality of turns in an annular shape and a metal plate layer formed by winding at least one metal plate extending in the tire width direction in an annular shape. Has been done.

Japanese Patent No. 3005190 Japanese Patent No. 2590189 JP-A-6-171323

Here, in the bead core formed by winding the bead wire in the tire circumferential direction, the bead wire arrangement may be broken due to the tension of the carcass generated during tire manufacturing. For example, in the bead core, the shape of the portion of the bead core on the tire radial direction inner side in the meridional section of the tire is likely to collapse into a shape that is convex to the inner side of the tire diameter due to the collapse of the arrangement of the bead wires. In this case, the contact pressure between the bead portion and the rim becomes local, and rim slippage may occur between the bead portion and the rim. When rim slippage occurs between the bead portion and the rim, the rubber of the bead base portion, which is the inner peripheral surface of the bead portion and is in contact with the rim, is easily worn away, and the durability is easily deteriorated.

As a method for making the shape of the bead core difficult to collapse, a method of adopting a bead core whose shape in the meridional section of the tire is hexagonal, which is less likely to cause shape collapse, is conceivable. Further, as a method for increasing the contact pressure between the bead portion and the rim, a method of reducing the inner diameter of the bead core can be considered. However, in the bead core having a hexagonal shape in the meridional section of the tire, the width of the bead core in the tire width direction becomes large, and thus the strain around the bead core may be too large. In this case, separation is likely to occur between members forming the bead portion, and durability may be deteriorated. Further, when the inner diameter of the bead core is made small, the pressure between the bead base portion and the rim when mounting the pneumatic tire on the rim wheel becomes high, which may deteriorate the rim assembly property.

The present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic tire capable of improving rim slip resistance and bead durability while ensuring rim assembly.

In order to solve the problems described above and achieve the object, a pneumatic tire according to the present invention has a core outer part formed by winding one or a plurality of bead wires in an annular shape and multiple turns, and the core outer part. Is arranged on the inner side in the tire radial direction, the inner peripheral surface in the tire radial direction is provided with a bead core having a reinforcing member that is curved in a direction in which the tire meridional section is convex toward the outer side in the tire radial direction, The relationship between the height H in the tire radial direction and the width W in the tire width direction of the bead core is within a range of 0.5≦(W/H)≦1.5, and the reinforcing member is the tire of the bead core. The relationship between the height H in the radial direction and the height hr in the tire radial direction of the reinforcing member is within the range of 0.05≦(hr/H)≦0.5, and the thickness t of the reinforcing member and The relationship between the width wr of the reinforcing member in the tire width direction is within the range of 3≦(wr/t)≦25, and the relationship between the amount d of the recess due to the bending of the reinforcing member and the thickness t of the reinforcing member is It is within the range of 0.2≦(d/t)≦1.2, and the relationship between the width wb of the outer side portion of the core in the tire width direction and the width wr of the reinforcing member in the tire width direction is 0.9≦. It is characterized in that (wr/wb)≦1.1.

In the pneumatic tire, it is preferable that the bead wire is covered with a covering rubber, and the reinforcing member has a rigidity higher than that of the covering rubber covering the bead wire.

Further, in the pneumatic tire, the reinforcing member is preferably made of a metal material.

Further, in the pneumatic tire, the bead core is a straight line connecting the inner end portion Pi in the tire width direction of the inner peripheral surface of the reinforcing member and the outer end portion Po in the tire width direction of the bead portion. The inclination angle with respect to the bead base portion located on the peripheral surface is preferably within ±5 degrees.

Further, in the above pneumatic tire, it is preferable that the reinforcing member be chamfered at inner portions in the tire radial direction at both end portions in the tire width direction.

Further, in the pneumatic tire, the bead portion is arranged on both sides of the tire equatorial plane in the tire width direction, and between the bead portions on both sides in the tire width direction, a carcass layer having a bias structure may be bridged. preferable.

In the pneumatic tire, it is preferable that the reinforcing member is wound in layers and laminated in the tire radial direction.

Further, in the pneumatic tire, it is preferable that the reinforcing member is attached to an inner peripheral surface of the outer side portion of the core in the tire radial direction.

The pneumatic tire according to the present invention has an effect that rim slip resistance and bead durability can be improved while ensuring rim assembly property.

FIG. 1 is a tire meridian cross-sectional view of a bead portion included in a pneumatic tire according to an embodiment. FIG. 2 is a modified example of the pneumatic tire according to the embodiment, and is a tire meridian cross-sectional view of a bead portion when the reinforcing member has one layer. FIG. 3 is an explanatory diagram showing a state in which the cover material is wound around the bead core of the pneumatic tire according to the embodiment. FIG. 4A is a chart showing the results of a performance evaluation test of a pneumatic tire. FIG. 4B is a chart showing the results of the performance evaluation test of the pneumatic tire. FIG. 4C is a chart showing the results of the performance evaluation test of the pneumatic tire.

Hereinafter, an embodiment of a pneumatic tire according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment. In addition, constituent elements in the following embodiments include elements that can be replaced by those skilled in the art and can be easily conceived, or elements that are substantially the same.

[Embodiment]
In the following description, the tire radial direction means a direction orthogonal to the tire rotation axis (not shown) that is the rotation axis of the pneumatic tire 1, and the tire radial direction inner side is the side facing the tire rotation axis in the tire radial direction. The outer side in the tire radial direction refers to the side away from the tire rotation axis in the tire radial direction. Further, the tire circumferential direction means a circumferential direction with the tire rotation axis as the central axis. Further, the tire width direction means a direction parallel to the tire rotation axis, the tire width direction inner side is a side toward the tire equatorial plane (tire equatorial line) in the tire width direction, and the tire width direction outer side is in the tire width direction. The side away from the tire equatorial plane. The tire equatorial plane is a plane that is orthogonal to the tire rotation axis and passes through the center of the tire width of the pneumatic tire 1. The tire equatorial plane is the tire width direction that is the center position of the pneumatic tire 1 in the tire width direction. The center line and the position in the tire width direction match. The tire width is the width in the tire width direction between the outermost portions in the tire width direction, that is, the distance between the portions most distant from the tire equatorial plane in the tire width direction. The tire equator line refers to a line on the tire equatorial plane and extending in the tire circumferential direction of the pneumatic tire 1. In the following description, the tire meridional section means a section when the tire is cut along a plane including the tire rotation axis.

FIG. 1 is a tire meridian sectional view of a bead portion 20 included in a pneumatic tire 1 according to an embodiment. The pneumatic tire 1 according to the embodiment has a pair of bead portions 20 arranged on both sides of the tire equatorial plane in the tire width direction. The pair of bead portions 20 are arranged inside the tire radial direction of a sidewall portion (not shown) where the pair of bead portions 20 are arranged on both sides of the tire equatorial plane in the tire width direction. A bead core 30 and a bead filler 21 are arranged in each of the pair of bead portions 20.

The carcass layer 10 is bridged between the bead portions 20 arranged on both sides of the tire equatorial plane in the tire width direction. The carcass layer 10 is bridged in a toroidal shape between the pair of bead portions 20 to form a skeleton of the pneumatic tire 1. Specifically, the carcass layer 10 is arranged from one bead portion 20 to the other bead portion 20 of a pair of bead portions 20 located on both sides in the tire width direction, and the vicinity of both end portions of the carcass layer 10 is The bead portion 20 is folded back in the tire width direction through the inside of the bead core 30 in the tire radial direction so as to surround the bead core 30 and the bead filler 21. That is, the carcass layer 10 has a carcass main body portion 15 spanned between the pair of bead portions 20 and a turn-up portion 16 formed continuously from the carcass main body portion 15 and folded back outward in the tire width direction. There is. Of these, the carcass body portion 15 is a portion formed in the carcass layer 10 between the inner sides of the bead cores 30 of the pair of bead portions 20 in the tire width direction. The turn-up portion 16 is formed continuously from the carcass body portion 15 on the inner side in the tire width direction of the bead core 30, and passes through the inner side of the bead core 30 in the tire radial direction to be folded back to the outer side in the tire width direction.

In addition, the carcass layer 10 is formed by stacking a plurality of carcass plies, and in the present embodiment, the carcass layer 10 is formed by stacking two carcass plies 11 and 12. In each of the carcass plies 11 and 12, a carcass cord (not shown) is inclined with respect to the direction in which the carcass layer 10 is spanned between the bead portions 20 and the tire circumferential direction. That is, the carcass layer 10 has a bias structure. Further, the carcass ply 11 and the carcass ply 12 are arranged so that the carcass cords of the carcass ply 11 and the carcass ply 12 intersect each other.

The bead core 30 arranged in the bead portion 20 is formed in an annular shape centered on the tire rotation axis and has a core outer portion 31 and a reinforcing member 40. The core outer portion 31 is configured by winding one or a plurality of bead wires 35 in an annular shape around the tire rotation axis and in multiple layers. Therefore, in the tire meridional section, the core outer portion 31 forms at least one row in which a plurality of winding portions of the bead wire 35 are arranged in the tire width direction and a plurality of layers that overlap in the tire radial direction.

For example, when the core outer portion 31 is composed of one bead wire 35, one bead wire 35 is spirally wound around the tire rotation axis, so that a plurality of circumferential portions are formed in the tire width direction. Is formed, and a plurality of layers are formed by winding the spiral so as to overlap in the tire radial direction. Further, when the core outer portion 31 is composed of a plurality of bead wires 35, each bead wire 35 is wound in a spiral shape around the tire rotation axis at the same position in the tire width direction, so that a plurality of bead wires 35 are formed. Is formed in the tire radial direction, and a plurality of spiral bead wires 35 are arranged in the tire width direction, thereby forming a row in which the plurality of winding parts are arranged in the tire width direction.

The bead wire 35 that constitutes the core outer portion 31 as described above is made of a metal material such as steel wire, and is covered with the covering rubber 36. The modulus of the covering rubber 36 covering the bead wire 35 at 100% elongation is in the range of 7.0 MPa or more and 12.0 MPa or less. The modulus at 100% elongation in this case is measured by a tensile test at 23° C. according to JIS K6251 (using dumbbell No. 3), and shows the tensile stress at 100% elongation.

The reinforcing member 40 is arranged inside the core outer side portion 31 in the tire radial direction, and is arranged at a position facing the inner peripheral surface 32 of the core outer side portion 31. Specifically, the reinforcing member 40 has a width in the tire width direction that is approximately the same as the width of the core outer portion 31, a position in the tire width direction that is substantially the same as a position of the core outer portion 31 in the tire width direction, and a core outer portion. It is arranged inside 31 in the tire radial direction. The reinforcing member 40 is made of a metal material, and thus the rigidity of the reinforcing member 40 is higher than the rigidity of the covering rubber 36 that covers the bead wire 35 forming the core outer portion 31.

The reinforcing member 40 made of a metal material is formed by so-called layer winding, in which a belt-shaped member is spirally wound around a tire rotation axis to form a layer in which a plurality of circumferential portions overlap in the tire radial direction. To be done. That is, in the reinforcing member 40, the belt-shaped member made of a metal material is layer-wound in such a direction that the width direction of the band is the tire width direction and the thickness direction of the band is the tire radial direction, and the circumferential portion is the tire. It is laminated in the radial direction. In the present embodiment, the reinforcing member 40 has three layers of the reinforcing member first layer 41, the reinforcing member second layer 42, and the reinforcing member third layer 43 from the tire radial direction inner side toward the tire radial direction outer side. It is stacked. That is, in the reinforcing member 40, the reinforcing member first layer 41 is located on the innermost side in the tire radial direction, and the reinforcing member third layer 43 is located on the outermost side in the tire radial direction, and is disposed on the inner peripheral surface 32 of the core outer portion 31. Facing each other.

Further, the reinforcing member 40 is curved such that the inner circumferential surface 45 in the tire radial direction is convex outward in the tire radial direction in the tire meridional section. That is, the reinforcing member 40 arranged in a direction in which the width direction of the belt-shaped member is the tire width direction and the thickness direction is the tire radial direction, the tire meridional cross-section has the vicinity of the center in the tire width direction of the reinforcing member 40. The reinforcing member 40 is positioned on the outer side in the tire radial direction with respect to the vicinity of both ends in the tire width direction, and is curved in a direction convex toward the outer side in the tire radial direction. In the reinforcing member 40 in which three layers are laminated, all of the three layers of the reinforcing member first layer 41, the reinforcing member second layer 42, and the reinforcing member third layer 43 are directed outward in the tire radial direction. Curved in a convex direction. Thereby, the reinforcing member 40 has an inner peripheral surface 45 in the tire radial direction of the reinforcing member 40, that is, the inner peripheral surface 45 in the tire radial direction of the reinforcing member first layer 41 located on the innermost side in the tire radial direction of the three layers. Is curved in a direction in which it is convex outward in the tire radial direction.

Since the inner peripheral surface 45 of the reinforcing member 40 is curved in such a manner as to be convex outward in the tire radial direction, the portion of the carcass layer 10 that passes through the tire radial inner side of the bead core 30 is inward. The circumferential surface 45 is arranged between both ends in the tire width direction. That is, the portion of the carcass layer 10 that passes through the inside of the bead core 30 in the tire radial direction mainly contacts near both ends of the inner peripheral surface 45 of the reinforcing member 40 in the tire width direction, and Most of the portion of the peripheral surface 45 located between both ends in the tire width direction is separated from the inner peripheral surface 45.

Further, the reinforcing member 40 is chamfered in the meridional section of the tire. Specifically, the reinforcing member 40 is chamfered at the tire radial direction inner side portions at both end portions in the tire width direction. That is, in the reinforcing member 40, the chamfered portions 46 are formed on the inner peripheral surface 45 side portions at both end portions in the tire width direction. The chamfered portion 46 of the reinforcing member 40 is formed, for example, by layer-rolling the strip-shaped member in a state in which one surface side is chamfered at both ends in the width direction of the strip-shaped member forming the reinforcing member 40. It

As described above, in the bead core 30 having the core outer portion 31 and the reinforcing member 40, the relationship between the height H in the tire radial direction and the width W in the tire width direction is 0.5≦(W/H)≦1. It is within the range of 0.5. The reinforcing member 40 arranged inside the core outer portion 31 in the tire radial direction has a relationship between the height H of the bead core 30 in the tire radial direction and the height hr of the reinforcing member 40 in the tire radial direction of 0. It is within the range of .05≦(hr/H)≦0.5. In the reinforcing member 40, the relationship between the width wb of the core outer side portion 31 in the tire width direction and the width wr of the reinforcing member 40 in the tire width direction is 0.9≦(wr/wb)≦1.1. It is inside.

The relationship between the height H of the bead core 30 in the tire radial direction and the height hr of the reinforcing member 40 in the tire radial direction is within the range of 0.10≦(hr/H)≦0.25. preferable. Further, in the present embodiment, the width wb of the core outer side portion 31 in the tire width direction is the same as the width W of the bead core 30 in the tire width direction, but the width wb of the core outer side portion 31 in the tire width direction. May be smaller than the width W of the bead core 30 in the tire width direction.

In the reinforcing member 40, the relationship between the thickness t of the reinforcing member 40 and the width wr of the reinforcing member 40 in the tire width direction is within the range of 3≦(wr/t)≦25. The thickness t of the reinforcing member 40 in this case is the thickness t of each layer when the circumferential portion of the reinforcing member 40 is laminated in the tire radial direction as in the pneumatic tire 1 according to the present embodiment. .. That is, the thickness t of the reinforcing member 40 is the thickness of the strip-shaped member forming the reinforcing member 40.

Further, in the reinforcing member 40, the relationship between the amount of depression d due to the bending of the reinforcing member 40 and the thickness t of the reinforcing member 40 is within the range of 0.2≦(d/t)≦1.2. The dent amount d of the reinforcing member 40 in this case is based on the straight line Lc connecting both ends of the inner circumferential surface 45 of the reinforcing member 40 in the tire width direction in the tire meridional section. Is the maximum distance between the inner peripheral surface 45 and the straight line Lc. That is, the recess amount d of the reinforcing member 40 is determined by the straight line Lc connecting the inner end portion Pi of the inner peripheral surface 45 of the reinforcing member 40 in the tire width direction and the outer end portion Po of the tire width direction and the inner diameter of the reinforcing member 40. It is the maximum distance from the peripheral surface 45. The portion of the carcass layer 10 that passes through the inner side of the bead core 30 in the tire radial direction is arranged between the inner end portion Pi and the outer end portion Po of the inner peripheral surface 45 of the reinforcing member 40. The relationship between the amount d of the recess of the reinforcing member 40 due to the curve and the thickness t of the reinforcing member 40 is preferably within the range of 0.3≦(d/t)≦0.8.

In addition, the sidewall portion located on the tire radial direction outer side of the bead portion 20 is curved between the bead portion 20 and the tread portion (not shown) in a direction convex toward the tire width direction outer side. The carcass layer 10 extending from the portion 20 to the outside in the tire radial direction extends toward the outside in the tire radial direction and extends toward the outside in the tire width direction so as to be along the sidewall portion. Therefore, the core outer portion 31 formed by winding the bead wire 35 is arranged such that the bead wires 35 are arranged from the inner side to the outer side in the tire radial direction along the carcass layer 10 that extends outward in the tire radial direction and extends outward in the tire width direction. As it goes, it deviates slightly in the direction toward the outside in the tire width direction. That is, in the bead wire 35, a plurality of layers are laminated in the tire radial direction, but a layer located closer to the tire radial direction outer side is located closer to the tire width direction outer side than a layer located closer to the tire radial direction inner side. The arrangement position is slightly displaced in the direction in which it is located. As a result, the bead wires 35 forming the core outer portion 31 are arranged such that the winding portions are arranged along the carcass layer 10.

Further, a rim cushion rubber 23 is arranged inside the bead core 30 in the tire radial direction in the bead portion 20. Specifically, the rim cushion rubber 23 is disposed outside the carcass layer 10 that is folded back along the bead core 30 in the bead portion 20, and extends from the tire width direction inner side of the bead core 30 to the tire radial direction inner side and the tire width direction outer side. It is arranged over the entire length of the tire and is continuously provided in the tire circumferential direction.

A bead base portion 25, which comes into contact with the rim wheel when the pneumatic tire 1 is assembled to the rim, is located on the inner peripheral surface of the bead portion 20. The bead base portion 25 is inclined with respect to the tire width direction or the tire rotation axis in a direction in which the diameter in the tire radial direction increases from the tire width direction inner side toward the tire width direction outer side. In this case, the bead base portion 25 is located inside the inner peripheral surface of the bead portion 20 in the tire radial direction inside a range between the inner end portion Pi and the outer end portion Po of the inner peripheral surface 45 of the reinforcing member 40. The range includes at least the part. That is, the bead base portion 25 is a tire whose position in the tire width direction on the inner peripheral surface of the bead portion 20 is in a range between the inner end portion Pi and the outer end portion Po of the inner peripheral surface 45 of the reinforcing member 40. It is a range that includes at least a portion at the same position as the position in the width direction.

In the bead core 30, the inclination angle θ of the straight line Lc connecting the inner end portion Pi of the inner peripheral surface 45 of the reinforcing member 40 in the tire width direction and the outer end portion Po in the tire width direction with respect to the bead base portion 25 is ±5. It is within the degree. That is, in the bead core 30, the inclination angle of the straight line Lc with respect to the tire width direction is substantially the same as the inclination angle of the bead base portion 25 with respect to the tire width direction. In this case, the inclination angle θ of the straight line Lc with respect to the bead base portion 25 is, for example, + when the inclination angle of the straight line Lc with respect to the tire width direction is larger than that of the bead base portion 25, and is larger than that of the bead base portion 25. The state where the straight line Lc is smaller is shown as −.

A method for arranging the reinforcing member 40 on the tire radial direction inner side of the core outer side portion 31 will be described. The reinforcing member 40 includes the inner peripheral surface of the core outer side portion 31 in the tire radial direction before incorporating the bead core 30 into the green tire. Paste it on 32. That is, the reinforcing member 40 contacts the inner peripheral surface 32 of the core outer portion 31 in a state where the adhesive is applied to the inner peripheral surface 32 of the core outer portion 31, the outer peripheral surface of the reinforcing member 40, or both. By doing so, it is attached to the inner peripheral surface 32 of the core outer portion 31 before being incorporated into the green tire. Thereby, in the bead core 30, the reinforcing member 40 is arranged inside the core outer portion 31 in the tire radial direction in a state where the inner peripheral surface 45 of the reinforcing member 40 is curved in a direction in which the inner peripheral surface 45 is convex outward in the tire radial direction. It will be installed in the green tire in the closed state. After that, the vulcanization molding of the green tire is performed, so that the bead core 30 has a configuration in which the reinforcing member 40 is arranged inside the core outer portion 31 in the tire radial direction.

When the pneumatic tire 1 according to the present embodiment is mounted on a vehicle, the rim wheel is fitted to the bead portion 20 to assemble the pneumatic tire 1 to the rim wheel, and the inside is filled with air. Attach it to the vehicle in the state of fretting. When a vehicle equipped with the pneumatic tire 1 travels, the pneumatic tire 1 rotates while a tread portion (not shown) contacts the road surface. The vehicle travels by transmitting a driving force or a braking force to the road surface or generating a turning force by a frictional force between the tread portion and the road surface. For example, when transmitting the driving force to the road surface, the power generated by a prime mover such as an engine of the vehicle is transmitted to the rim wheel, and is transmitted from the rim wheel to the bead portion 20 to be transmitted to the pneumatic tire 1. To be done.

Part of the force transmitted to the pneumatic tire 1 is received by the carcass layer 10 forming the skeleton of the pneumatic tire 1. The carcass layer 10 is arranged between the bead portions 20 located on both sides in the tire width direction, and most of the force transmitted between the bead portion 20 and the rim wheel is received by the carcass layer 10. It is possible.

Here, in the vulcanization process of the green tire (not shown) at the time of manufacturing the pneumatic tire 1, the green tire is put into a mold for vulcanization molding, and a bladder (not shown) is put inside the green tire. , The green tire is inflated by inflating the bladder and pressed against the mold. Thereby, while vulcanizing the rubber member constituting the green tire, molding such as formation of grooves formed in the tread portion is performed. In the vulcanizing step, the green tire is inflated by the bladder. Tension acts on the carcass layer 10 arranged over the entire length.

Since the carcass layer 10 is folded back along the bead core 30 between the bead portions 20 on both sides in the tire width direction, when a tension acts on the carcass layer 10 during vulcanization molding, the bead core 30 has a tension of the carcass layer 10. Force is transmitted. Since the carcass layer 10 is folded back along the bead core 30 from the tire width direction inner side of the bead core 30 to the tire width direction outer side, the tension transmitted from the carcass layer 10 to the bead core 30 is the tire on the inner peripheral surface of the bead core 30. An attempt is made to rotate the bead core 30 in a direction in which the vicinity of the end portion on the outer side in the width direction is directed to the inner side in the tire width direction and the end portion on the inner peripheral surface of the bead core 30 on the inner side in the tire width direction is directed to the outer side in the tire radial direction. Acts as a force. Therefore, in the bead core 30, the arrangement of the bead wires 35 that form the rows and layers to form the bead core 30 is likely to collapse. When the bead wire 35 is dislocated into a shape in which the inner peripheral surface of the bead core 30 is convex inward in the tire radial direction in the meridional section of the tire, the contact pressure between the bead portion 20 and the rim wheel is large when the rim is assembled. It becomes easy for the part to become local. When the portion where the contact pressure between the bead portion 20 and the rim wheel is large becomes local, the portion where the contact pressure becomes small is also likely to occur, so that rim slippage occurs between the bead portion 20 and the rim wheel. Sometimes.

On the other hand, in the present embodiment, the reinforcing member 40 is arranged inside the core outer portion 31 formed by winding the bead wire 35 in the tire radial direction. For this reason, even when tension from the carcass layer 10 acts on both sides in the tire width direction on the inner peripheral surface of the bead core 30 during vulcanization molding, the tension from the carcass layer 10 can be received by the reinforcing member 40. Thus, the tension applied to the bead core 30 from the carcass layer 10 at the time of vulcanization suppresses the disposition of the bead wire 35 such that the inner peripheral surface of the bead core 30 collapses into a shape protruding inward in the tire radial direction. Therefore, the shape of the inner peripheral surface of the bead core 30 can be maintained in a desired shape. Therefore, when the rim is assembled, it is possible to prevent the portion where the contact pressure between the bead portion 20 and the rim wheel is large from becoming local, and it is possible to make the contact pressure uniform, so that the bead portion 20. The occurrence of rim slip between the wheel and the rim wheel can be suppressed.

Further, since the reinforcing member 40 is curved such that the inner peripheral surface 45 in the tire radial direction is convex outward in the tire radial direction, the shape of the inner peripheral surface of the bead core 30 is convex inward in the tire radial direction. It is possible to secure the rigidity of the reinforcing member 40 in the tire width direction and the tire radial direction without making the shape of Thereby, even when the tension from the carcass layer 10 acts on the bead core 30 during vulcanization molding, it is possible to more reliably prevent the inner peripheral surface of the bead core 30 from being convex inward in the tire radial direction. it can. Therefore, when the rim is assembled, it is possible to more reliably prevent the portion where the contact pressure between the bead portion 20 and the rim wheel is large from becoming localized, so that between the bead portion 20 and the rim wheel. It is possible to more reliably suppress the occurrence of rim slip.

Further, since the relationship between the height H in the tire radial direction and the width W in the tire width direction of the bead core 30 is within the range of 0.5≦(W/H)≦1.5, It is possible to more reliably suppress the rim slip between the bead portion 20 and the rim wheel while suppressing the separation of the members. That is, when the relationship between the height H and the width W of the bead core 30 is (W/H)<0.5, the width W of the bead core 30 is too small, so that the pneumatic tire 1 is not attached to the rim wheel. When the rim is assembled, the contact pressure of the portion of the bead base portion 25 located inside the bead core 30 in the tire radial direction with respect to the rim wheel may locally increase. In this case, since a portion where the contact pressure between the bead portion 20 and the rim wheel is small is likely to occur, it may be difficult to suppress rim slip between the bead portion 20 and the rim wheel. When the relationship between the height H and the width W of the bead core 30 is (W/H)>1.5, the width W of the bead core 30 is too large, so that a large load is applied to the bead portion 20. Further, the strain generated around the bead core 30 may be too large. In this case, due to the large strain, separation occurs between the bead core 30 and the rubber member around the bead core 30, or a member such as the carcass layer 10 located around the bead core 30 and the rubber member around the bead core 30 are separated from each other. If separation occurs between them, the bead durability, which is the durability of the bead portion 20, may be easily deteriorated.

On the other hand, when the relationship between the height H and the width W of the bead core 30 is within the range of 0.5≦(W/H)≦1.5, the contact pressure of the bead base portion 25 with respect to the rim wheel is The bead portion 20 and the rim wheel are spread over a wide range in which it is possible to suppress the local increase and to prevent the strain generated around the bead core 30 from becoming too large. An appropriate amount of contact pressure can be generated between them. As a result, the separation of the members around the bead core 30 can be suppressed to ensure the bead durability, and the rim slip between the bead portion 20 and the rim wheel can be suppressed more reliably.

In the reinforcing member 40, the relationship between the height H of the bead core 30 in the tire radial direction and the height hr of the reinforcing member 40 in the tire radial direction is within a range of 0.05≦(hr/H)≦0.5. Therefore, the occurrence of rim slip caused by the local contact pressure between the bead portion 20 and the rim wheel is more reliably suppressed, while the carcass layer 10 is prevented from being damaged and the bead durability is more reliably ensured. Can be secured. That is, when the relationship between the height H of the bead core 30 and the height hr of the reinforcing member 40 is (hr/H)<0.05, the height hr of the reinforcing member 40 with respect to the height H of the bead core 30 is Since it is too low, it may be difficult to ensure the rigidity of the reinforcing member 40. In this case, when the tension from the carcass layer 10 acts on the bead core 30 during vulcanization molding, it may be difficult to suppress the deformation of the reinforcing member 40 by the force from the carcass layer 10, and the bead portion 20 and the rim wheel There is a possibility that it may be difficult to suppress the local increase of the contact pressure. Further, when the relationship between the height H of the bead core 30 and the height hr of the reinforcing member 40 is (hr/H)>0.5, the height hr of the reinforcing member 40 with respect to the height H of the bead core 30 is Since the height is too high, the height of the core outer portion 31 in the tire radial direction may be too low. In this case, since the contact area between the carcass layer 10 and the core outer portion 31 becomes small, when the tension from the carcass layer 10 acts on the bead core 30 during vulcanization molding, the force acting from the carcass layer 10 causes the bead wire 35 to move. Displacement is less likely to occur. Therefore, stress concentration is likely to occur in the carcass layer 10 near a position in contact with a position closer to the outer end of the bead core 30 in the tire radial direction, and the carcass layer 10 is easily damaged, so that the bead durability is improved. There is a risk that it will become worse. Further, when the relationship between the height H of the bead core 30 and the height hr of the reinforcing member 40 is (hr/H)>0.5, the height hr of the reinforcing member 40 with respect to the height H of the bead core 30 is Since it is too high, the rigidity of the reinforcing member 40 may be too high. In this case, it is difficult to suppress the local increase in the contact pressure between the bead portion 20 and the rim wheel, so that there is a possibility that the contact pressure between the bead portion 20 and the rim wheel becomes too large. Therefore, there is a possibility that the rim-assembling property may deteriorate when the pneumatic tire 1 is assembled on the rim wheel.

On the other hand, when the relationship between the height H of the bead core 30 and the height hr of the reinforcing member 40 is within the range of 0.05≦(hr/H)≦0.5, the carcass layer 10 and the core outside The rigidity of the reinforcing member 40 can be ensured by ensuring the height hr of the reinforcing member 40 while suppressing the contact area with the portion 31 from becoming too small. As a result, at the position closer to the inner end of the bead core 30 in the tire radial direction, the reinforcing member 40 can be prevented from being deformed by the force from the carcass layer 10 during vulcanization molding, and the bead portion 20 and the rim wheel are It is possible to suppress the local increase in the contact pressure. Further, at a position near the outer end of the bead core 30 in the tire radial direction, the contact area between the carcass layer 10 and the core outer part 31 can be ensured, so that the force acting from the carcass layer 10 to the core outer part 31 can be used. It is possible to prevent the stress concentration from occurring in the carcass layer 10 due to the displacement of the bead wire 35. Therefore, it is possible to more reliably suppress the occurrence of rim slip due to the local contact pressure, suppress damage to the carcass layer 10, and more reliably ensure the bead durability. Further, by setting the relationship between the height H of the bead core 30 and the height hr of the reinforcing member 40 to be (hr/H)≦0.5, the rigidity of the reinforcing member 40 becomes too large, and the bead portion 20 and the rim are rimmed. It is possible to prevent the contact pressure with the wheel from becoming too large, and it is possible to prevent deterioration of the rim assembly property when the pneumatic tire 1 is assembled to the rim wheel.

Further, in the reinforcing member 40, since the relationship between the thickness t and the width wr in the tire width direction is within the range of 3≦(wr/t)≦25, the contact pressure becomes too large and the rim assembly property deteriorates. While suppressing this, it is possible to more reliably suppress the occurrence of rim slip caused by the local contact pressure between the bead portion 20 and the rim wheel. That is, when the relationship between the thickness t and the width wr of the reinforcing member 40 is (wr/t)<3, the thickness t of the reinforcing member 40 is too thin, and it may be difficult to secure the rigidity of the reinforcing member 40. There is. In this case, when the tension from the carcass layer 10 acts on the bead core 30 during vulcanization molding, it may be difficult to suppress the deformation of the reinforcing member 40 by the force from the carcass layer 10, and the bead portion 20 and the rim wheel There is a possibility that it may be difficult to suppress the local increase of the contact pressure. Further, when the relationship between the thickness t and the width wr of the reinforcing member 40 is (wr/t)>25, the thickness t of the reinforcing member 40 is too thick, and therefore the rigidity of the reinforcing member 40 may be too high. is there. In this case, it is difficult to suppress the local increase in the contact pressure between the bead portion 20 and the rim wheel, so that there is a possibility that the contact pressure between the bead portion 20 and the rim wheel becomes too large. Therefore, there is a possibility that the rim-assembling property may deteriorate when the pneumatic tire 1 is assembled on the rim wheel.

On the other hand, when the relationship between the thickness t and the width wr of the reinforcing member 40 is within the range of 3≦(wr/t)≦25, the rigidity of the reinforcing member 40 becomes too large and the bead portion 20 and The rigidity of the reinforcing member 40 can be ensured while suppressing the occurrence of a portion where the contact pressure with the rim wheel becomes too large. As a result, it is possible to prevent the reinforcing member 40 from being deformed by the force from the carcass layer 10 during vulcanization molding while suppressing the contact pressure from becoming too large and deteriorating the rim assembly property. It is possible to suppress the local increase in the contact pressure between the wheel and the rim wheel. Therefore, it is possible to more reliably suppress the occurrence of rim slip due to the local contact pressure while suppressing deterioration of the rim assembly property.

Further, in the reinforcing member 40, the relationship between the amount of depression d due to the bending of the reinforcing member 40 and the thickness t of the reinforcing member 40 is within the range of 0.2≦(d/t)≦1.2, so that the bead portion It is possible to more reliably suppress the occurrence of rim slippage due to the local contact pressure between the rim wheel 20 and the rim wheel, while suppressing damage to the carcass layer 10 and more reliably ensuring bead durability. .. That is, when the relationship between the recess amount d and the thickness t of the reinforcing member 40 is (d/t)<0.2, the recess amount d is too small, and therefore the reinforcing member 40 is curved even if the reinforcing member 40 is curved. It may be difficult to effectively improve the rigidity of the. In this case, even if the reinforcing member 40 is curved, it may be difficult to suppress the deformation of the reinforcing member 40 due to the force acting on the bead core 30 from the carcass layer 10 during vulcanization molding. There is a possibility that it may be difficult to suppress the local increase of the contact pressure. Further, when the relationship between the amount d of the recess of the reinforcing member 40 and the thickness t is (d/t)>1.2, the amount d of the recess is too large, and therefore the reinforcing member 40 is curved by bending. There is a risk that the rigidity of the will become too large. In this case, at the time of vulcanization molding, stress concentration is likely to occur near the portion of the carcass layer 10 that contacts the end portion of the reinforcing member 40 in the tire width direction, and the carcass layer 10 is easily damaged, so that the bead durability is improved. There is a risk that it will become worse.

On the other hand, when the relationship between the recess amount d and the thickness t of the reinforcing member 40 is within the range of 0.2≦(d/t)≦1.2, the rigidity of the reinforcing member 40 becomes too large. As a result, the rigidity of the reinforcing member 40 can be secured while suppressing the stress concentration of the carcass layer 10 from becoming too large. As a result, it is possible to prevent the reinforcing member 40 from being deformed during vulcanization molding while suppressing the stress concentration of the carcass layer 10 from becoming too large and the carcass layer 10 being easily damaged. It is possible to suppress the local increase in the contact pressure with the rim wheel. Therefore, it is possible to more reliably suppress the occurrence of rim slip due to the local contact pressure, suppress damage to the carcass layer 10, and more reliably ensure the bead durability.

In the bead core 30, the relationship between the width wb of the core outer portion 31 in the tire width direction and the width wr of the reinforcing member 40 in the tire width direction is within the range of 0.9≦(wr/wb)≦1.1. Therefore, it is possible to suppress the occurrence of separation in the bead portion 20 while suppressing localization of the portion where the contact pressure increases. That is, when the relationship between the width wb of the core outer portion 31 in the tire width direction and the width wr of the reinforcing member 40 in the tire width direction is (wr/wb)<0.9, the width wr of the reinforcing member 40 is Since it is too small, it may be difficult to suppress localization of a portion where the contact pressure between the bead portion 20 and the rim wheel is large. Further, when the relationship between the width wb of the core outer portion 31 in the tire width direction and the width wr of the reinforcing member 40 in the tire width direction is (wr/wb)>1.1, the width wr of the reinforcing member 40 is Since it is too large, the strain generated around the bead core 30 when a large load acts on the bead portion 20 may be too large. In this case, due to the large strain, separation is likely to occur in the bead portion 20, and the bead durability may be deteriorated. On the other hand, when the relationship between the width wb of the core outer side portion 31 and the width wr of the reinforcing member 40 is within the range of 0.9≦(wr/wb)≦1.1, the width wr of the reinforcing member 40. It is possible to suppress the occurrence of the separation in the bead portion 20 while suppressing the local increase of the contact pressure by ensuring the above. As a result, rim slip resistance and bead durability can be improved while ensuring the rim assembly property.

Further, since the rigidity of the reinforcing member 40 is higher than the rigidity of the covering rubber 36 that covers the bead wire 35, the rigidity of the position of the bead core 30 on the inner side in the tire radial direction, that is, the rigidity of the inner peripheral surface side of the bead core 30, The reinforcing member 40 can more reliably increase the height. As a result, the deformation of the bead core 30 on the inner peripheral surface side during vulcanization molding can be suppressed, and the occurrence of rim slip can be more reliably suppressed. As a result, the rim slip resistance can be improved more reliably.

Moreover, since the reinforcing member 40 is made of a metal material, the rigidity of the reinforcing member 40 can be ensured more reliably. That is, since the reinforcing member 40 is made of a metal material, it is possible to more reliably increase the rigidity of the reinforcing member 40 compared with the covering rubber 36 that covers the bead wire 35 of the core outer portion 31. As a result, the rigidity of the entire reinforcing member 40 can be increased more reliably than the rigidity of the core outer portion 31 around which the bead wire 35 is wound. Therefore, even when the tension from the carcass layer 10 acts on the bead core 30, the shape of the inner peripheral surface of the bead core 30 can be more surely maintained in a desired shape, and the bead portion 20 and the rim wheel when assembled to the rim can be improved. The contact pressure with can be made uniform. As a result, the rim slip resistance can be improved more reliably.

In the bead core 30, the inclination angle θ of the straight line Lc connecting the inner end Pi and the outer end Po of the inner peripheral surface 45 of the reinforcing member 40 with respect to the bead base 25 is within ±5 degrees. It is possible to more surely make the contact pressure uniform. In other words, since the straight line Lc of the bead core 30 is substantially parallel to the bead base portion 25, the bead portion 20 with respect to the rim wheel that can be generated by the bead core 30 when the bead portion 20 is rim-assembled to the rim wheel. The contact pressure can be made uniform. As a result, a portion where the contact pressure between the bead portion 20 and the rim wheel becomes too large hardly occurs, so that the rim assembly property can be improved and the rim slip caused by the local contact pressure can be prevented. The occurrence can be suppressed more reliably. As a result, the rim slip resistance can be improved while ensuring the rim assembly property more reliably.

Further, since the reinforcing member 40 is chamfered on the tire radial direction inner side portions at both end portions in the tire width direction, the contact area between the end portion of the reinforcing member 40 in the tire width direction and the carcass layer 10 becomes too small. Can be suppressed. As a result, it is possible to prevent stress concentration from occurring in the carcass layer 10 in the vicinity of a portion where the end portion of the reinforcing member 40 in the tire width direction and the carcass layer 10 contact each other, and to prevent damage to the carcass layer 10 more. It can be surely suppressed. As a result, the bead durability can be more reliably improved.

Further, the carcass layer 10 has a bias structure, and the bead core 30 is a so-called layer winding bead core 30 in which the bead wires 35 are arranged in a lattice in a meridional section of the tire. By using the reinforcing member 40, the rim slip resistance can be more reliably improved. In other words, in the pneumatic tire 1 in which the carcass layer 10 has the bias structure, the bead core 30 has a circumferential portion of the bead wire 35 in each row when a plurality of rows of the bead wire 35 are stacked in the tire radial direction in the tire meridional section. In many cases, a so-called layer winding bead core 30 is used in which the positions in the tire width direction are almost the same between different rows. In such a layer-wound bead core 30, the arrangement of the bead wire 35 is easily collapsed due to the tension of the carcass layer 10 in the vulcanization step during the production of the pneumatic tire 1, and the contact pressure from the bead portion 20 to the rim wheel is increased. The arrangement of the bead wire 35 near the inner peripheral surface of the bead core 30, which has a great influence on the position, is also likely to collapse.

On the other hand, in the present embodiment, the reinforcing member 40 is arranged inside the core outer portion 31 formed by winding the bead wire 35 in the tire radial direction. Therefore, even in the layer-wound bead core 30, the rigidity with respect to the tension of the carcass layer 10 at the time of vulcanization molding can be secured at a position closer to the inner peripheral surface of the bead core 30. Therefore, it is possible to prevent the contact pressure on the rim wheel from being locally caused by the tension of the carcass layer 10 acting on the bead core 30 and the arrangement of the bead wire 35 collapses at a position closer to the inner peripheral surface of the bead core 30. Therefore, it is possible to make the contact pressure of the bead portion 20 to the rim wheel uniform when the bead portion 20 is assembled to the rim wheel. As a result, the rim slip resistance can be improved more reliably.

Further, since the reinforcing member 40 is formed by layer-rolling band-shaped members made of a metal material and stacking the members in the tire radial direction, the reinforcing member 40 having a plurality of layers can be easily formed. Accordingly, the rigidity of the reinforcing member 40 arranged inside the core outer portion 31 in the tire radial direction can be easily and reliably ensured. As a result, the rim slip resistance can be improved more easily and surely.

Further, since the reinforcing member 40 is attached to the inner peripheral surface 32 of the core outer side portion 31 in the tire radial direction, the reinforcing member 40 that is a member different from the core outer side portion 31 in the tire radial direction of the core outer side portion 31 is used. It can be easily placed inside. That is, the bead core 30 is incorporated into the green tire in a state where the reinforcing member 40 is attached to the inner peripheral surface 32 of the core outer portion 31, and thereafter, the vulcanization molding of the green tire is performed. The reinforcing member 40 may be arranged inside the portion 31 in the radial direction of the tire. This makes it possible to easily secure the rigidity of the bead core 30 at a position closer to the inner peripheral surface. As a result, the rim slip resistance can be improved more easily.

[Modification]
In addition, in the above-described embodiment, the reinforcing member 40 is laminated in the tire radial direction by winding the belt-shaped member made of a metal material in layers, but may be laminated in the tire radial direction by other than layer winding. The reinforcing member 40 may have a plurality of layers stacked by stacking a plurality of members in the tire radial direction, for example.

Further, in the above-described embodiment, the reinforcing member 40 is formed by stacking strip-shaped members, but the reinforcing member 40 may not be stacked. FIG. 2 is a modified example of the pneumatic tire 1 according to the embodiment, and is a tire meridian cross-sectional view of the bead portion 20 when the reinforcing member 40 has one layer. The reinforcing member 40 may be formed as a single layer, for example, as shown in FIG. That is, the reinforcing member 40 may have a single layer of a belt-shaped member and may be formed in an annular shape around the tire rotation axis. The reinforcing member 40 is arranged on the inner side in the tire radial direction of the core outer portion 31 regardless of the number of layers laminated in the tire radial direction, and the inner peripheral surface 45 of the reinforcing member 40 in the tire radial direction in the tire meridional section. It may be formed in a shape that curves in a direction that is convex outward in the tire radial direction. Regardless of the number of laminated layers in the tire radial direction, the reinforcing member 40 is curved in a direction in which the inner peripheral surface 45 is convex outward in the tire radial direction, so that the shape of the inner peripheral surface of the bead core 30 is formed in the tire radial direction inside. The rigidity of the reinforcing member 40 can be ensured without forming a convex shape. This makes it possible to more reliably prevent the inner peripheral surface of the bead core 30 from being convex inward in the tire radial direction during vulcanization molding, and when the rim is assembled, the bead portion 20 and the rim wheel are Since it is possible to more reliably suppress the local increase in the contact pressure, it is possible to more reliably suppress the occurrence of rim slip.

Further, in the above-described embodiment, the reinforcing member 40 is attached to the inner peripheral surface 32 of the core outer portion 31 in the tire radial direction, but the reinforcing member 40 is attached to the core outer portion 31 by a method other than attaching. It may be arranged on the inner side in the tire radial direction. FIG. 3 is an explanatory diagram showing a state in which the cover material 50 is wound around the bead core 30 of the pneumatic tire 1 according to the embodiment. Before incorporating the bead core 30 into the green tire, for example, as shown in FIG. 3, the core outer portion 31 and the reinforcing member 40 may be bound and fixed with a cover material 50. In this case, the cover material 50 is, for example, a belt-shaped sheet made of a rubber material or a belt-shaped sheet made of a resin material such as nylon, and the belt-shaped cover material 50 includes the core outer portion 31 and the reinforcing member 40. In the integrated state, it is spirally wound around the outer peripheral surface of the bead core 30 formed in an annular shape. As a result, the cover member 50 binds the core outer portion 31 and the reinforcing member 40 together and fixes them together. In the bead core 30, by binding and fixing the core outer side portion 31 and the reinforcing member 40 with the cover material 50 as described above, the ease at the time of manufacturing can be improved, and the core outer side portion 31 and the reinforcing member 40 can be relatively opposed to each other. The bead core 30 can be arranged in the bead portion 20 with a desired positional relationship. Thereby, the rim slip resistance and the bead durability can be improved more easily.

Further, in the above-described embodiment, the reinforcing member 40 is only formed of the metal material, but the reinforcing member 40 formed of the metal material may be covered with the covering rubber. By covering the reinforcing member 40 made of a metal material with the covering rubber, the covering rubber plays a role of a cushioning material, so that stress concentration is suppressed from occurring in a portion of the carcass layer 10 that is in contact with the reinforcing member 40. You can As a result, damage to the carcass layer 10 can be more reliably suppressed, and bead durability can be more reliably improved.

Further, in the above-described embodiment, the reinforcing member 40 is made of a metal material, but the reinforcing member 40 may be made of other material. The reinforcing member 40 may be formed of a relatively rigid member such as FRP (Fiber Reinforced Plastics). That is, the reinforcing member 40 may be formed of a member whose rigidity is higher than that of the covering rubber 36 that covers the bead wire 35. The rigidity mentioned here includes, for example, bending rigidity, hardness, tensile strength and the like. That is, the reinforcing member 40 may have a bending rigidity, a hardness, and a tensile strength higher than those of the covering rubber 36 that covers the bead wire 35. Since the reinforcing member 40 is formed of a member having high rigidity, it is possible to prevent the shape of the inner peripheral surface of the bead core 30 from being convex toward the inner side in the tire radial direction. The contact pressure of 20 can be made uniform, and the rim slip resistance can be improved.

Further, the above-described embodiments and modified examples may be combined as appropriate. The bead core 30 arranged in the bead portion 20 has a core outer side portion 31 formed by winding a bead wire 35 and a reinforcing member 40 arranged inside the core outer side portion 31 in the tire radial direction. H and the width W, the height hr of the reinforcing member 40, the width wr of the reinforcing member 40, the thickness t of the reinforcing member 40, the recess amount d of the reinforcing member 40, and the width wb of the core outer portion 31 have a predetermined relationship. By being formed as described above, the rim slip resistance and the bead durability can be improved while ensuring the rim assembly property.

[Example]
4A to 4C are charts showing the results of the performance evaluation test of the pneumatic tire. Hereinafter, with respect to the above pneumatic tire 1, performances performed on a conventional pneumatic tire, a pneumatic tire 1 according to the present invention, and a pneumatic tire of a comparative example to be compared with the pneumatic tire 1 according to the present invention. The evaluation test will be described. The performance evaluation test is performed on rim slip resistance which is performance against rim slip, bead separation resistance which is performance against separation between members arranged in the bead portion 20, and rim assembly property which is ease of rim assembly. Was tested.

In the performance evaluation test, a test tire with a nominal tire ID specified by JATMA of ID 6.50-10 was assembled on a JATMA standard rim wheel, and the air pressure was adjusted to the air pressure specified by JATMA. The test was carried out by mounting it on a known forklift and applying a load specified by JATMA.

Regarding the rim slip resistance, the evaluation method of each test item is to mark the test tire and the rim wheel before running on the test vehicle, and measure the tire circumferential direction of the test tire and the rim wheel after running for 2000 hours. It was evaluated by measuring the amount of deviation. The rim slip resistance is represented by an index with a conventional example described below being 100, and the larger the value, the less likely the test tire and the rim wheel are displaced in the tire circumferential direction, indicating that the rim slip resistance is excellent.

The bead separation resistance was evaluated by running the test vehicle for 4000 hours and then removing the test tire from the rim wheel and confirming the occurrence of separation at the bead portion 20. The bead separation resistance is represented by an index with a conventional example described later being 100, and the larger the value, the less the separation occurs in the bead portion 20, indicating that the bead separation resistance is excellent.

In addition, as for the rim assembly property, an operator installs a test tire on a JATMA standard rim wheel without eccentric fitting, measures the time required until the internal pressure is filled, and the reciprocal of the measured time will be described later. The index is represented by an index with the conventional example being 100. The larger the index value, the shorter the required time and the better the rim assembly. As for the rim assembly property, if the index is 97 or more, it is assumed that the same rim assembly property as that of the conventional example can be secured.

The performance evaluation test compares a conventional pneumatic tire that is an example of a conventional pneumatic tire, Examples 1 to 11 that are the pneumatic tire 1 according to the present invention, and the pneumatic tire 1 according to the present invention. It carried out about 23 types of pneumatic tires with Comparative Examples 1-11 which are pneumatic tires. Among these, in the pneumatic tires of Conventional Example and Comparative Example 1, the bead core 30 does not have the reinforcing member 40. In the pneumatic tires of Comparative Examples 2 to 11, although the bead core 30 has the reinforcing member 40, the relationship between the height H and the width W of the bead core 30 is 0.5≦(W/H)≦. It is not within the range of 1.5, or the relationship between the height H of the bead core 30 and the height hr of the reinforcing member 40 is within the range of 0.05≦(hr/H)≦0.5. Or the relationship between the thickness t of the reinforcing member 40 and the width wr of the reinforcing member 40 is not within the range of 3≦(wr/t)≦25, or the recess amount d of the reinforcing member 40 and The relationship with the thickness t of the reinforcing member 40 is not within the range of 0.2≦(d/t)≦1.2, or the width wb of the core outer portion 31 and the width wr of the reinforcing member 40. The relationship is not within the range of 0.9≦(wr/wb)≦1.1.

On the other hand, in Examples 1 to 11, which are examples of the pneumatic tire 1 according to the present invention, the bead core 30 has the reinforcing member 40, and the relationship between the height H and the width W of the bead core 30 is 0. Within the range of 5≦(W/H)≦1.5, the relationship between the height H of the bead core 30 and the height hr of the reinforcing member 40 is within the range of 0.05≦(hr/H)≦0.5. , And the relationship between the thickness t of the reinforcing member 40 and the width wr of the reinforcing member 40 is within the range of 3≦(wr/t)≦25, the relationship between the depth d of the reinforcing member 40 and the thickness t of the reinforcing member 40 is 0. Within the range of 2≦(d/t)≦1.2, the relationship between the width wb of the core outer portion 31 and the width wr of the reinforcing member 40 is within the range of 0.9≦(wr/wb)≦1.1. It has become. Further, in the pneumatic tires 1 according to Examples 1 to 11, the inclination angle θ of the straight line Lc connecting the inner end Pi and the outer end Po of the inner peripheral surface 45 of the reinforcing member 40 with respect to the bead base 25 is large. , Each is different.

As a result of performing a performance evaluation test using these pneumatic tires 1, as shown in FIGS. 4A to 4C, the pneumatic tires 1 according to Examples 1 to 11 have the same rim assembly property as that of the conventional example. It was found that both the rim slip resistance and the bead durability can be improved as compared with the conventional example while ensuring the above. That is, the pneumatic tires 1 according to Examples 1 to 11 can improve the rim slip resistance and the bead durability while ensuring the rim assembly property.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 10 Carcass layer 11, 12 Carcass ply 15 Carcass body part 16 Turn-up part 20 Bead part 21 Bead filler 23 Rim cushion rubber 25 Bead base part 30 Bead core 31 Core outside part 32 Inner peripheral surface 35 Bead wire 36 Covering rubber 40 Reinforcing member 41 Reinforcing member first layer 42 Reinforcing member second layer 43 Reinforcing member third layer 45 Inner peripheral surface 46 Chamfered portion 50 Cover material

Claims (8)

A core outer part formed by winding one or a plurality of bead wires in an annular shape and in multiple turns,
A reinforcing member that is arranged on the inner side in the tire radial direction of the core outer portion, and the inner peripheral surface in the tire radial direction is curved in a direction that is convex toward the tire radial direction outer side in the tire meridional section,
A bead core having a bead core,
In the bead core, the relationship between the height H in the tire radial direction and the width W in the tire width direction is within a range of 0.5≦(W/H)≦1.5,
The reinforcing member is
The relationship between the height H of the bead core in the tire radial direction and the height hr of the reinforcing member in the tire radial direction is within a range of 0.05≦(hr/H)≦0.5,
The relationship between the thickness t of the reinforcing member and the width wr of the reinforcing member in the tire width direction is within the range of 3≦(wr/t)≦25,
The relationship between the amount of depression d due to the bending of the reinforcing member and the thickness t of the reinforcing member is within the range of 0.2≦(d/t)≦1.2,
The relationship between the width wb of the outer side portion of the core in the tire width direction and the width wr of the reinforcing member in the tire width direction is within a range of 0.9≦(wr/wb)≦1.1. Pneumatic tires. The bead wire is covered with a covering rubber,
The pneumatic tire according to claim 1, wherein the reinforcing member has a rigidity higher than that of the coating rubber that covers the bead wire. The pneumatic tire according to claim 1, wherein the reinforcing member is made of a metal material. The bead core is a bead base portion located on the inner peripheral surface of the bead portion, which is a straight line connecting an inner end portion Pi in the tire width direction and an outer end portion Po in the tire width direction of the inner peripheral surface of the reinforcing member. The pneumatic tire according to any one of claims 1 to 3, wherein an inclination angle with respect to is within ±5 degrees. The pneumatic tire according to any one of claims 1 to 4, wherein the reinforcing member has chamfered inner portions in the tire radial direction at both end portions in the tire width direction. The bead portion is arranged on both sides of the tire equatorial plane in the tire width direction,
The pneumatic tire according to any one of claims 1 to 5, wherein a carcass layer having a bias structure is bridged between the bead portions on both sides in the tire width direction. The pneumatic tire according to claim 1, wherein the reinforcing member is wound in layers and laminated in a tire radial direction. The pneumatic tire according to any one of claims 1 to 7, wherein the reinforcing member is attached to an inner peripheral surface of the outer side portion of the core in the tire radial direction.

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