JP6989370B2 - Pneumatic radial tire - Google Patents

Description

The present disclosure relates to pneumatic radial tires for heavy loads.

Pneumatic radial tires for heavy loads used for trucks and buses are required to have higher internal pressure and higher load than general passenger car tires, and therefore, improvement in durability is required.

As a document showing an example of the structure of a radial tire, Patent Document 1 describes a steel carcass provided between a pair of bead portions and a pair of bead portions, and the end portions are wound around a bead core and locked. Tires with a ply and an outer steel cheer located outside the steel carcass ply with respect to the bead core are disclosed.

Japanese Unexamined Patent Publication No. 7-164838

When internal pressure is applied to the tire, a force acts on the steel carcass ply in the direction of being pulled out. At the winding end of the steel carcass ply, a direct strain toward the outer side in the tire radial direction is developed to counter the pulling out. Since the direct distortion causes the separation of the winding end of the carcass ply, it is preferable to reduce it.

If the winding end of the carcass ply is arranged high on the outer side in the tire radial direction, the direct distortion becomes small. However, the winding end of the carcass ply is close to the sidewall portion where there is a lot of deformation. Then, the shear strain due to the deformation acts on the winding end of the carcass ply, which causes separation.

On the other hand, if the winding end of the carcass ply is arranged low in the radial direction of the tire, the shear strain due to the deformation acting on the winding end of the carcass ply can be reduced. However, since the length of the winding portion of the carcass ply is shortened, the force against the pulling out of the carcass ply is weak when an internal pressure is applied, and the direct distortion becomes large, which causes a failure of the bead portion.

Due to the above circumstances, the position of the winding end of the conventional carcass ply is designed in consideration of the balance between the shear strain and the direct strain due to the above deformation.

The present disclosure has been made in view of such circumstances, and an object thereof is to provide a pneumatic radial tire having improved durability of a bead portion.

The pneumatic radial tires disclosed in this disclosure are
A pair of bead parts with a bead core,
A steel carcass ply provided between the pair of bead portions, the end of which is locked while being wound around the bead core, and has a steel cord.
An inner steel cheer that is placed inside the steel carcass ply with respect to the bead core and is wound up on the bead core.
A wedge member sandwiched between the inner steel chain and the steel carcass ply on the outer side of the bead core in the tire width direction and formed in a tapered shape toward the winding side is provided.

In this way, since the wedge member is sandwiched between the inner steel chainer and the steel carcass ply on the outer side in the tire width direction of the bead core, even if a force pulling the steel carcass ply toward the winding side acts on the steel carcass ply, the inner steel chain C and the wedge member function as a stopper to prevent them from coming off, and direct distortion can be reduced.
Further, since the pull-out resistance of the steel carcass ply is increased, the position of the winding end of the carcass ply can be lowered inward in the radial direction of the tire, and the shear strain due to deformation can be reduced from acting on the winding end.
Therefore, it is possible to improve the durability.

Tire meridian cross-sectional view showing a tire of one embodiment Cross-sectional view of the tire meridian showing an enlarged bead A cross-sectional view of the tire meridian showing an enlarged bead portion of a modified example. A cross-sectional view of the tire meridian showing an enlarged bead portion of a modified example. A cross-sectional view of the tire meridian showing an enlarged bead portion of a modified example.

Hereinafter, the pneumatic radial tire according to the embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the tire meridian. FIG. 2 is a cross-sectional view of the tire meridian showing an enlarged bead portion. FIG. 3 is a diagram corresponding to FIG. 2 showing a modified example. FIG. 4 is a diagram corresponding to FIG. 2 showing a modified example.

As shown in FIG. 1, the pneumatic radial tire includes a pair of bead portions 1, a sidewall portion 2 extending from each bead portion 1 to the tire radial outer RD1, and both sidewall portions 2 in the tire radial outer RD1. It is provided with a tread portion 3 connected to the end. The bead portion 1 is provided with an annular bead core 10 formed by coating a convergent body such as a steel wire with rubber, and a bead filler 11 made of hard rubber. The bead core 10 is formed in a polygonal shape in the cross section of the tire meridian. In the present embodiment, it is a hexagon, but the present invention is not limited to this, and for example, a quadrangle is exemplified.

Further, this tire includes a toroid-shaped steel carcass ply 4 extending from the tread portion 3 to the bead portion 1 via the sidewall portion 2. The steel carcass ply 4 is provided between the pair of bead portions 1 and the end portions thereof are locked in a wound state via the bead core 10. The steel carcass ply 4 is formed by covering a steel cord extending substantially at right angles to the tire circumferential direction PD with a topping rubber. Inside the steel carcass ply 4, an inner liner rubber 5 for holding air pressure is arranged.

Further, a sidewall rubber 6 is provided on the outside of the steel carcass ply 4 in the sidewall portion 2. Further, on the outside of the steel carcass ply 4 in the bead portion 1, a rim strip rubber 7 that comes into contact with a rim (not shown) when the rim is mounted is provided.

On the outside of the steel carcass ply 4 in the tread portion 3, a belt (not shown), a belt reinforcing material (not shown), a base rubber (not shown), and a cap rubber (not shown) are inside. It is provided in order from the outside to the outside. The belt and the belt reinforcing material are provided to reinforce the steel carcass ply 4. The belt is composed of a plurality of steel cord layers. The belt reinforcing material is configured by covering a cord extending in the tire circumferential direction with topping rubber. The belt reinforcing material may be omitted if necessary.

As shown in FIG. 2, the bead portion 1 has an inner steel chain 12, an outer steel chain 13, and a wedge member 8. The outer steel chain 13 may be omitted as shown in FIG.

The inner steel cheha 12 is arranged inside the steel carcass ply 4 with respect to the bead core 10. A part is wound around the bead core 10. The inner steel chain 12 is a member in which a steel cord inclined with respect to the tire circumferential direction PD is covered with rubber.

As shown in FIG. 2, with reference to the tire radial outer end 10a (upper end) of the bead core 10, the tire cross-sectional height Ha of the winding end 12a of the inner steel chain 12 and the tire cross section of the winding end 4a of the steel carcass ply 4. The relationship with the height hb is preferably 0 <Ha / Hb <0.5. If this relationship is satisfied, the member separation of the winding end 12a of the inner steel chain 12 can be suppressed. This is because if Ha / Hb> 0.5, the shearing force acting on the winding end 12a of the inner steel chain 12 becomes high, which may lead to separation.

The outer steel cheha 13 is arranged outside the steel carcass ply 4 with respect to the bead core 10. The outer steel cheha 13 is wound around the bead core 10 together with the steel carcass ply 4. The outer steel chain 13 is a member in which a steel cord inclined with respect to the tire circumferential direction PD is covered with rubber.

Here, "rolled up" means that the member is arranged from the tire radial inner RD2 of the bead core 10 through the tire width outer WD1 of the bead core 10 toward the tire radial outer RD1. The “winding side DD1” means a direction toward the end 4a (winding end 4a) of the outer WD1 of the steel carcass ply 4 in the tire width direction along the steel carcass ply 4 in the tire meridian cross section. The “engagement side DD2” means a direction toward the tread portion 3 along the steel carcass ply 4 in the cross section of the tire meridian.

The wedge member 8 is sandwiched between the inner steel cheha 12 and the steel carcass ply 4 on the outer WD1 in the tire width direction of the bead core 10, and is formed in a tapered shape toward the winding side DD2. In the embodiment shown in FIG. 2, the member 8 has a triangular shape, but is not limited thereto. The wedge member 8 may be made of only rubber, or may be a member in which a cord inclined with respect to the tire circumferential direction PD is covered with rubber. If the wedge member 8 contains rubber, the surrounding steel carcass ply 4 and the inner steel cheer 12 are covered with rubber, so that the affinity is good and the member separation can be suppressed.

When the wedge member 8 is a cord member coated with rubber, a steel cord is exemplified as the cord. When the wedge member 8 is a cord member coated with rubber, the cord is preferably inclined by 20 to 50 degrees with respect to the tire circumferential direction PD, and more preferably 25 degrees to 45 degrees.

Regardless of whether the wedge member 8 is made of only rubber or a ply material, the hardness of the rubber contained in the wedge member 8 is arbitrary, but is higher than the rubber hardness of the surrounding bead filler 11. Is preferable. The rubber hardness is JISK6253-1-2012 3.2 durometer hardness. The function as a stopper by the wedge member 8 is easily exerted.

As described above, if the wedge member 8 is sandwiched between the inner steel cheha 12 and the steel carcass ply 4 in the outer WD1 in the tire width direction of the bead core 10, the force for pulling the steel carcass ply 4 into the winding side DD2 is applied. When acted on, the inner steel chain 12 and the wedge member 8 function as stoppers to prevent them from coming off.

As shown in FIG. 2, it is preferable that the tire radial inner end 8a of the wedge member 8 is arranged on the tire radial inner RD2 rather than the center of gravity 10c of the bead core 10. With this configuration, the wedge member 8 uses the bead core 10 as a scaffold, so that the function as a stopper is easily exhibited. Of course, if the wedge member 8 is arranged between the inner steel chain 12 and the steel carcass ply 4, the tire radial inner end 8a of the wedge member 8 is the tire radial outer RD1 of the bead core 10 center of gravity 10c. It may be arranged in. This is because it functions as a stopper.

As shown in FIG. 2, the opening angle θ between the inner steel cheer 12 opened by the wedge member 8 and the steel carcass ply 4 is preferably 10 or more, more preferably 15 degrees or more. This is because if this opening angle θ is secured, the function of the wedge member as a stopper can be further exerted.

In order to properly exert the function as a stopper by the wedge member 8, as shown in FIGS. 2 and 3, the winding end 12b of the inner steel chain 12 is larger than the winding side end 10d on the bottom surface 10b of the bead core 10. It is preferably arranged on the entrainment side DD2. The bottom surface 10b of the bead core 10 is a side that intersects the perpendicular line from the center of gravity 10c of the bead core 10. According to this configuration, the operation of pulling in the steel carcass ply 4 and the movement of the inner steel cheer 12 are easily linked.

As shown in FIG. 2, in the case of a tire in which the outer steel chain 13 is arranged on the outer side of the steel carcass ply 4 with respect to the bead core 10, the winding end 12b of the inner steel chain 12 is from the winding end 12a. Is also preferably arranged on the inner RD2 in the radial direction of the tire. Since the outer steel chain 13 is arranged on the outside of the steel carcass ply 4, the outer steel chain 13 fulfills the function of suppressing the carcass ply 4 from collapsing. By that amount, the winding end of the inner steel chain can be lowered. If the winding end 12b of the inner steel chain 12 can be lowered, the shear strain acting on the winding end 12a of the inner steel chain 12 can be suppressed, and the shear strain acting toward the winding end 12a and the tread of the inner steel chain 12 can be suppressed. Since the distance between the steel carcass ply 4 can be secured, there is an advantage that the inclination of the wedge can be taken larger.

FIG. 4 is a modified example in which the outer steel chain is omitted. That is, no steel chain other than the inner steel chain 12 is arranged on the outside of the steel carcass ply 4 with the bead core 10 as a reference. In the case of this structure, it is preferable that the winding end 12b of the inner steel chain 12 is arranged on the outer RD1 in the tire radial direction with respect to the winding end 12a. Since the steel chain is not arranged on the outside of the steel carcass ply 4, the winding end 12b of the inner steel chain 12 is raised to ensure durability.

FIG. 5 is a modification applicable to the examples of FIGS. 2 to 4. As shown in FIG. 5, a second inner steel cheer 9 is provided between the wedge member 8 and the steel carcass ply 4. With this configuration, the resistance to the steel carcass ply 4 coming off is improved, so that the function as a stopper can be further strengthened. In the example shown in FIG. 5, the outer steel chain 13 is provided, but the outer steel chain 13 can be omitted.

As described above, the pneumatic radial tire of this embodiment is
A pair of bead portions 1 having a bead core 10 and
A steel carcass ply 4 provided between the pair of bead portions 1 and locked with the ends wound around the bead core 10 and having a steel cord.
The inner steel cheha 12 placed inside the steel carcass ply 4 with respect to the bead core 10 and wound up on the bead core 10 and
A wedge member 8 sandwiched between the inner steel cheer 12 and the steel carcass ply 4 on the outer WD1 in the tire width direction of the bead core 10 and formed in a tapered shape toward the winding side DD2.
To prepare for.

In this way, since the wedge member 8 is sandwiched between the inner steel cheha 12 and the steel carcass ply 4 in the outer WD1 in the tire width direction of the bead core 10, a force for pulling the steel carcass ply 4 into the winding side DD2 acts on the steel carcass ply 4. Even so, the inner steel chafer 12 and the wedge member 8 function as stoppers to prevent them from coming off, and direct distortion can be reduced.
Further, since the pull-out resistance of the steel carcass ply 4 is increased, the position of the winding end 4a of the steel carcass ply 4 can be lowered to the inner RD2 in the tire radial direction, and the shear strain due to deformation is reduced from acting on the winding end 4a. can.
Therefore, it is possible to improve the durability.

In the present embodiment, the tire radial inner end 8a of the wedge member 8 is arranged on the tire radial inner RD2 with respect to the center of gravity 10c of the bead core 10.

According to this configuration, since the wedge member 8 uses the bead core 10 as a scaffold, the function of the wedge member 8 as a stopper is strongly exhibited, and the durability can be improved.

In the present embodiment, the opening angle θ between the inner steel cheer 12 opened by the wedge member 8 and the steel carcass ply 4 is 10 degrees or more.

According to this configuration, the function of the wedge member 8 as a stopper can be further exerted, and the durability can be improved.

In the present embodiment, the bead core 10 is formed in a polygonal shape in the cross section of the tire meridian, and the winding end 12b of the inner steel cheer 12 is arranged on the winding side DD2 more than the winding side end 10d on the bottom surface 10b of the bead core 10. Has been done.

According to this configuration, the operation of pulling in the steel carcass ply 4 and the movement of the inner steel cheer 12 are easily linked, so that the function as a stopper by the wedge member 8 is easily exerted, and the durability is improved. Is possible.

In the present embodiment, the wedge member 8 contains rubber.

According to this configuration, since the steel carcass ply 4 and the inner steel chain 12 are coated with rubber, they have a good affinity and can suppress separation.

In the present embodiment, the bead portion 1 has the bead filler 11, and the rubber contained in the wedge member 8 has a hardness higher than the rubber hardness of the bead filler 11.

According to this configuration, the function of the wedge member 8 as a stopper is easily exerted, and the durability can be improved.

In the present embodiment, the wedge member 8 is a member in which a steel cord inclined with respect to the tire circumferential direction PD is covered with rubber.

According to this configuration, since the rigidity is increased by the cord, the function as a stopper by the wedge member 8 is easily exerted, and the durability can be improved.

In the present embodiment, a second inner steel cheer 9 is provided between the wedge member 8 and the steel carcass ply 4.

According to this configuration, the resistance to the steel carcass ply 4 coming off is improved, so that the function as a stopper can be further strengthened.

In the example of FIG. 2, an outer steel chainer 13 is provided outside the steel carcass ply 4 with respect to the bead core 10 and is wound around the bead core 10 together with the steel carcass ply 4, and the winding end 12b of the inner steel chainer 12 is It is arranged on the inner side RD2 in the tire radial direction from the winding end 12a.

According to this configuration, since the outer steel chain 13 is arranged on the outside of the steel carcass ply 4, the outer steel chain 13 fulfills the function of suppressing the carcass ply 4 from collapsing. By that amount, the winding end 12b of the inner steel chain 12 can be lowered. If the winding end 12b of the inner steel chain 12 can be lowered, the shear strain acting on the winding end 12a of the inner steel chain 12 can be suppressed, and the shear strain acting toward the winding end 12a and the tread of the inner steel chain 12 can be suppressed. Since the distance between the steel carcass ply 4 can be secured, there is an advantage that the inclination of the wedge can be taken larger.

In the example of FIG. 4, no steel chain other than the inner steel chain 12 is arranged on the outside of the steel carcass ply 4 with respect to the bead core 10, and the winding end 12b of the inner steel chain 12 is a winding end. It is arranged on the outer side RD1 in the tire radial direction from 12a.

According to this configuration, since the steel chain is not arranged on the outside of the steel carcass ply 4, the winding end of the inner steel chain 12 is raised to ensure durability.

Although the embodiments of the present invention have been described above with reference to the drawings, it should be considered that the specific configuration is not limited to these embodiments. The scope of the present invention is shown not only by the description of the above-described embodiment but also by the scope of claims, and further includes all modifications within the meaning and scope equivalent to the scope of claims.

It is possible to adopt the structure adopted in each of the above embodiments in any other embodiment. The specific configuration of each part is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present disclosure.

1 bead part 10 bead core 10b bottom of bead core 10c center of gravity of bead core 10d winding side end at bottom of bead core 11 bead filler 12 inner steel chain 12a winding end of inner steel chain 12b winding end of inner steel chain 13 outer steel chain 4 Steel car casp ply 8 Wedge member 8a Tire radial inner end of wedge member RD1 Tire radial outer RD2 Tire radial inner WD1 Tire width outer θ Opening angle

Claims (8)

A pair of bead parts with a bead core,
A steel carcass ply provided between the pair of bead portions, the end of which is locked while being wound around the bead core, and has a steel cord.
An inner steel cheer that is placed inside the steel carcass ply with respect to the bead core and is wound up on the bead core.
A wedge member sandwiched between the inner steel chain and the steel carcass ply on the outer side in the tire width direction of the bead core and formed in a tapered shape toward the winding side is provided .
The wedge member contains rubber and is
The bead portion has a bead filler and has a bead filler.
The rubber contained in the wedge member is a pneumatic radial tire having a hardness higher than the rubber hardness of the bead filler. The tire according to claim 1, wherein the tire radial inner end of the wedge member is arranged inside the tire radial direction with respect to the center of gravity of the bead core. The tire according to claim 1 or 2, wherein the opening angle between the inner steel chain and the steel carcass ply opened by the wedge member is 10 degrees or more. The bead core is formed in a polygonal shape in the cross section of the tire meridian.
The tire according to any one of claims 1 to 3, wherein the winding end of the inner steel chain is arranged on the winding side further from the winding side end on the bottom surface of the bead core. The tire according to claim 1 , wherein the wedge member is a member in which a steel cord inclined with respect to the tire circumferential direction is covered with rubber. The tire according to any one of claims 1 to 5 , wherein a second inner steel cheer is provided between the wedge member and the steel carcass ply. It is provided with an outer steel cheer that is located outside the steel carcass ply with respect to the bead core and is wound around the bead core together with the steel carcass ply.
The tire according to any one of claims 1 to 6 , wherein the winding end of the inner steel chain is arranged inside the winding end in the radial direction of the tire. No steel chain other than the inner steel chain is arranged on the outside of the steel car cusply with the bead core as a reference.
The tire according to any one of claims 1 to 6 , wherein the winding end of the inner steel chain is arranged outside the winding end in the radial direction of the tire.

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