JPH07232519A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To reduce rolling resistance and save fuel consumption of a vehicle by lightening a tire. CONSTITUTION:This pneumatic tire has a sectional triangular bead apex 9 extending from a bead core 5 toward an outer mold in the tire radial direction among a carcass 6, a belt layer, a main body part 6A of the carcass 6 and a folded back part 6B, and this bead apex 9 is constituted of a honeycomb body 10 with a central line of a hole part 11 surrounded by thin pieces and aligned in the tire axial direction and a foaming body 12 filled in the hole part 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire capable of reducing rolling resistance, reducing fuel consumption of a vehicle, and improving heat dissipation of a bead portion and maintaining durability by reducing the weight of a tire. Regarding tires.

[0002]

2. Description of the Related Art In recent years, as part of the improvement of the global environment, energy saving has been demanded, and in order to save fuel consumption even in automobiles, it is an important issue to reduce the weight of tires as well as the vehicle.

In a pneumatic tire, a bead apex is provided in the bead portion in order to maintain the vertical rigidity of the tire and increase the lateral rigidity thereof. The bead apex has a hollow structure having a plurality of holes. It has been proposed, for example, in Japanese Patent Laid-Open Nos. 4-59402 and 4-95513 to reduce the weight of the tire.

[0004]

However, in the above proposal, since air is present in the holes of the apex,
There is a problem that tires are damaged as a result of the heat generated by the increase in tire temperature during traveling staying in the holes of the apex without being dissipated.

According to the present invention, the honeycomb body made of a material having a high elastic modulus is used to increase the lateral rigidity and reduce the capacity of the bead apex, and the pores of the honeycomb body are filled with foam to suppress heat generation during running. It is an object of the present invention to provide a pneumatic tire that can reduce the fuel consumption of a vehicle while maintaining the durability while reducing the weight of the tire.

[0006]

According to the present invention, there is provided a carcass having a folded-back portion that passes from a tread portion through a sidewall portion and folds around a bead core of a bead portion, and is disposed inside the tread portion and radially outside the carcass. In a pneumatic tire having a belt layer, and a bead apex having a triangular cross-section extending from the bead core outward in the tire radial direction between the carcass main body part and the folded-back part, the bead apex is more than the rubber of the bead part. A honeycomb body in which pores surrounded by thin pieces made of a material having a high elastic modulus are aligned, and a foam body filled in the pores of the honeycomb body and having a lower elastic modulus than the honeycomb body It is a pneumatic tire characterized by.

The honeycomb body is formed by using metal, plastic resin or fiber reinforced plastic material. The holes may be hexagonal holes or polygonal holes of triangular or larger size as long as they are aligned holes.

Further, the axis of the hole may be arranged in the circumferential direction with respect to the tire axis, or in the tire circumferential direction, or in a direction inclined with respect to the tire axis or the circumferential direction. The expansion ratio of the foamed rubber composition is preferably 5 to 40%.

[0009]

The bead apex has a honeycomb body in which holes surrounded by thin pieces having a high elastic modulus are aligned. Therefore, the capacity of the bead apex can be reduced while maintaining the rigidity as compared with the conventional bead apex that is formed of solid hard rubber. Further, the composite of thin pieces of the honeycomb body can significantly reduce the volume specific gravity, thereby achieving the weight reduction of the tire. Further, as the weight of the tire is reduced, the rolling resistance is reduced and the fuel consumption of the vehicle can be reduced.

In the honeycomb body, the shape and size of the hole and the direction of the hole can be appropriately selected, and the longitudinal rigidity, lateral rigidity and torsional rigidity of the tire can be adjusted without changing the basic dimensions of the tire. It is possible to adjust the setting, and it is possible to adapt to the diversification of various running performances of tires.

Further, since the hole is filled with foam, the carcass is damaged by the cord being exposed by the invasion of the topping rubber of the carcass, and the air accumulated in the hole generates heat generated during tire running. Therefore, the risk of breakage of the bead portion and detachment of the rim caused by the temperature of the bead portion can be eliminated. Moreover, since the material to be filled in the pores is a foam, the volume specific gravity is small, and the weight of the bead apex is not significantly increased.

As described above, according to the present invention, by organically combining and integrating the above-described components, the heat dissipation of the bead portion is improved, the durability is maintained, the weight of the tire is reduced, and the rolling resistance is improved. By reducing the amount, it is possible to promote low fuel consumption. Moreover, the rigidity of the sidewall portion can be easily adjusted, and driving performance such as steering stability and riding comfort can be improved.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, a pneumatic tire 1 has a sidewall portion 3 extending inward in the radial direction from both ends of a tread portion 2 and a bead portion 4 located at the radially inner end of the sidewall portion 3. In addition, a toroidal carcass 6 in which a body 6A that passes through the tread portion 2 and the sidewall portion 3 and reaches the bead core 5 of the bead portion 4 is provided with a turnback portion 6B that is folded back around the bead core 5, and the tread portion 2 And the belt layer 7 are disposed inside and outside the carcass 6 in the radial direction. Further, the main body portion 6 of the carcass 6
A bead apex 9 having a triangular cross-section extending from the bead core 5 outward in the tire radial direction is provided between A and the folded portion 6B.

In the present embodiment, the carcass 6 is composed of one or more carcass plies in which the carcass cords are in a radial or semi-radial arrangement with the carcass cord inclined at an angle of 70 to 90 ° with respect to the tire equator C. As the carcass cord, a steel cord is used in addition to organic fibers such as nylon, rayon and aromatic polyamide.

The belt layer 7 is made of organic fiber such as nylon, rayon, aromatic polyamide or the like, or a belt cord made of steel, and inner and outer two layers of belt plies 7A and 7B.
The belt cord is formed at an angle of 10 to 30 ° with respect to the tire equator C and the inner and outer belt plies 7A,
In 7B, they are oriented so as to be inclined in opposite directions. In this embodiment, the belt width WB, which is the width of the belt layer 7 in the tire axial direction, is set in the range of 0.7 to 1.1 times the tread width WT.

The bead apex 9 has a triangular cross-section that tapers outwardly in the radial direction from the bead core 5, and in this embodiment, the bead apex height which is the height from the bead base line L at the outer end P in the radial direction. HB is set to 0.3 to 0.5 times the tire section height H.
The carcass 6 is formed as a so-called low turn-up in which the height HC of the folded-back portion 6B from the bead base line L is set smaller than the bead apex height HB.

The bead apex 9 is a honeycomb body 1.
0 and the foam 12 filled in the pores 11 of the honeycomb body 10.

The honeycomb body 10 has a sufficiently higher elastic modulus than the rubber of the bead portion, for example, a polymer material made of a polyurethane-based, polyamide-based, epoxy-based, or polyolefin-based resin having a viscosity of more than 200 kg / cm ² , or FRP. Of the fiber-reinforced plastic, and further, having the hole portion 11 surrounded by a thin piece 14 having a thickness t of 0.025 to 0.2 mm, and the hole portion 11 is aligned and opens on both side faces in a honeycomb shape. Is formed. It is preferable that the minimum dimension of the hole portion 11, that is, the inner opposite side dimension l in this embodiment is 3.2 to 5 mm. Note that rubber may be used as the honeycomb body 10. When using rubber, JISA hardness is 90 °
It should be as hard as possible at about 120 °.

In this embodiment, the honeycomb body 10 is arranged so that the central axis of the hole 11 is oriented in the tire axial direction.

In this embodiment, as shown in FIG. 3, the honeycomb body 10 is a regular hexagonal tubular body 15 formed by extruding the polymer material and surrounded by a thin piece 14.
The hexagonal hole portions 11 are aligned by connecting the respective sides to the sides of the adjacent cylindrical bodies 15 and joining them. As shown in FIG. 4, a thin metal piece 1 made of aluminum is used.
It can also be formed by joining between 4 and 14 over the length of the side a that faces up and down, and then widening and bending in the lateral direction.

Further, as shown in FIG. 5, a cylindrical body 15 having a triangular cross section.
It can also be formed by using A, and the hole portion may be formed as a polygonal hole such as a rectangle or a rhombus.

Further, the honeycomb body 10 can also be formed by integrally molding with a mold using a rubber material, a synthetic resin material or the like. In addition, it can be formed by sequentially bending an ultra-thin steel sheet using spring steel, which is a metal material, and when this spring steel is used, a large local deformation is locally generated in the bead portion like during run flat. Even if it occurs, the spring steel having high elasticity facilitates elastic recovery and prevents permanent deformation of the tire.

The foam 12 has a foaming ratio of 5 to 40%.
It is formed by the rubber foam rubber composition of. For example, Table 1
A rubber having a desired expansion ratio can be obtained by using the rubber compositions of the compositions B to G shown in the above.

[0024]

[Table 1]

The bead portion 4 is provided with a chafer 19 which is arranged along the outward surface of the carcass 6 and is made of a ply reinforced with a steel cord.

FIG. 6 shows another embodiment of the bead apex 9A. In this example, the holes 11A of the honeycomb body 10 are arranged with their center lines oriented in the tire axial direction.

By forming the tire in this manner, the lateral rigidity can be increased among the longitudinal and lateral rigidity of the tire.

In this example, the bead apex 9A is
A cover 17 is provided along the tire axially outwardly facing surface 9a and the inwardly facing surface 9b and covers the opening of the hole of the honeycomb body 10.

In the present embodiment, the cover 17 is located between the body portion 6A of the carcass 6 and the inwardly facing surface 9b in the vicinity of the outer end P of the bead apex 9, and in the present embodiment, the bead core 5 starts from a position beyond the outer end P. Nobiatsu and bead core 5
And is folded in a U-shape, passing between the folded-back portion 6B of the carcass 6 and the outward surface 9a and beyond the outer end P. The cover 17 is formed of a rubber-lined plain woven cloth, and further reliably protects the carcass, the rubber of the bead portion, and the like at the open end of the honeycomb body 10.

[0030]

SPECIFIC EXAMPLES Tires (Examples 1 to 6) having a tire size of 11R22.5 and having the configurations shown in FIGS. 1 and 2 were prototyped according to the specifications shown in Table 2 and their performances were tested. A conventional tire having a solid speed apex (conventional example) and a tire having a configuration other than that of the present invention were also tested and their performances were compared.

The test was conducted according to the following procedure. (1) Steering stability A test tire was mounted on a standard rim, a specified internal pressure was applied, and it was mounted on the front and rear wheels of an actual vehicle, and it was driven on a general road. It is displayed with the index. The larger the value, the better.

(2) Durability After the actual vehicle of the item (1) was run for 50,000 km, the wear amount of the tread surface was judged by the reduction of the groove and displayed as an index with 100 as the conventional example. The larger the value, the better.

(3) Tire Weight The tire weight is shown as a weight% ratio with the conventional example being 100. The test results are shown in Table 2.

[0034]

[Table 2]

As a result of the test, it was confirmed that the weight of each of the examples could be reduced, and the steering stability and durability could be improved.

[0036]

As described above, the pneumatic tire of the present invention is
The bead apex consists of a honeycomb body having aligned pores and arranging the pores in the tire axial direction, and a foam filled in the pores, so the lateral rigidity of the tire is high and the capacity of the bead apex is high. By reducing the size of the tire and reducing the weight of the tire, the rolling resistance of the tire can be reduced, the fuel consumption of the vehicle can be reduced, and durability and steering stability can be maintained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a bead portion thereof.

FIG. 3 is a perspective view illustrating a honeycomb body.

FIG. 4 is a front view schematically showing another example of the honeycomb body.

FIG. 5 is a cross-sectional view showing another example of a honeycomb body.

FIG. 6 is a sectional view showing another embodiment of the bead portion.

[Explanation of symbols]

 2 tread part 3 sidewall part 4 bead part 5 bead core 6 carcass 6A main body part 6B folded part 7 belt layer 9 bead apex 10 honeycomb body 11 hole 12 foam

Claims (4)

[Claims] 1. A carcass having a turnback portion that passes through a sidewall portion from a tread portion and turns back around a bead core of a bead portion, a belt layer disposed inside the tread portion and radially outside the carcass, and a body of the carcass. In a pneumatic tire having a bead apex having a triangular cross-section extending outward from the bead core in the tire radial direction between the bent portion and the folded portion, the bead apex is made of a material having a higher elastic modulus than the rubber of the bead portion. A pneumatic tire comprising a honeycomb body in which pores surrounded by thin flakes are aligned, and a foam filled in the pores of the honeycomb body and having a lower elastic modulus than the honeycomb body. 2. The pneumatic tire according to claim 1, wherein the honeycomb body has holes arranged in the tire circumferential direction. 3. The pneumatic tire according to claim 1, wherein the honeycomb body has holes arranged in the tire axial direction. 4. The pneumatic tire according to claim 1, wherein the foam is a foamed rubber composition having a foaming ratio of 5 to 40%.