JP2763855B2 - Pneumatic tire - Google Patents

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 the weight while improving the driving stability and riding comfort of a vehicle.

[0002]

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

[0003] In a pneumatic tire, a bead apex is provided at a bead portion in order to maintain the longitudinal rigidity of the tire and increase the lateral rigidity. The bead apex has a hollow structure having a plurality of holes. For example, Japanese Patent Application Laid-Open Nos. Hei 4-59402 and Hei 4-95513 propose to reduce the weight of tires.

[0004]

However, in the above proposal, the opening end of the hole provided in the tire axial direction comes into contact with the carcass or the side wall rubber, and when the green tire is vulcanized and formed, the carcass is not in contact with the carcass. In some cases, the topping rubber tends to penetrate into the hole, and as a result, the cord of the carcass is exposed and the cord is damaged. In addition, as a result of the presence of air in the apex, there is a problem that damage is caused due to a rise in temperature due to use.

The present invention uses a low-density hard urethane foam material having closed cells to achieve weight reduction without reducing the capacity of a bead apex and to increase lateral rigidity by regulating tensile strength and compressive strength. An object of the present invention is to provide a pneumatic tire capable of solving the above-mentioned problems, reducing the weight of the tire and improving steering stability, and reducing fuel consumption of a vehicle.

[0006]

According to the present invention, there is provided a carcass having a folded portion which turns from a tread portion through a sidewall portion and around a bead core of a bead portion, and is disposed inside the tread portion and radially outside the carcass. A belt layer, and a pneumatic tire having a bead apex having a triangular cross section extending from the bead core radially outward between the carcass main body portion and the folded portion, the bead apex is made of a hard urethane foam material. It is a pneumatic tire characterized by becoming.

The bead apex made of the above-mentioned hard urethane foam material preferably has a triangular cross-section extending radially outwardly based on the axial width of the bead core.

[0008]

The bead apex is made of a hard urethane material whose tensile strength and compressive strength are regulated. Therefore, the lateral rigidity can be increased as compared with a conventional bead apex formed of a hard rubber solid. Further, by using a hard urethane material having a lower specific gravity than rubber, the weight of the bead apex can be reduced and the weight of the tire can be reduced. In addition, the rolling resistance can be reduced as the tire weight is reduced, and the fuel efficiency of the vehicle can be reduced.

Further, by selecting a hard urethane material, it is possible to adjust and set the longitudinal rigidity, the lateral rigidity and the torsional rigidity of the tire without changing the basic dimensions of the tire. Can be adapted to

[0010]

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 radially inward from both ends of a tread portion 2, and a bead portion 4 located at a radially inner end of the sidewall portion 3. And a toroidal carcass 6 having a folded portion 6B which is turned around the bead core 5 on a main body 6A which extends to the bead core 5 of the bead portion 4 through the tread portion 2 and the sidewall portion 3, and the tread portion 2 And the belt layer 7 is disposed inside and inside the carcass 6 in the radial direction. The main body 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 comprises one or more carcass plies in which the carcass cords are arranged at an angle of 70 to 90 ° with respect to the tire equator C, in this embodiment, one carcass ply. As the cord, a steel cord is used in addition to organic fibers such as nylon, rayon, and aromatic polyamide.

The belt layer 7 is composed of inner and outer belt plies 7A and 7B using a belt cord made of an organic fiber such as nylon, rayon or aromatic polyamide or steel.
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 while being tilted in opposite directions. In the present embodiment, the belt width WB, which is the width of the belt layer 7 in the tire axial direction, is set in a range of 0.7 to 1.1 times the tread width WT.

The bead apex 9 has a triangular cross-section extending radially outward from the bead core 5, and in this embodiment, a bead apex height which is the height of the radially outer end P from the bead base line L. The height 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 portion 6B from the bead base line L is set smaller than the bead apex height HB.

The bead apex 9 is formed of a hard urethane foam 12, and the hard urethane foam 12 is manufactured by, for example, the following method.

Example of Producing Rigid Urethane Foam First Stage D. I. 247 Puracol TP 440 50 Water (contained in polyether) 0.05 However, “TDI” is an abbreviation of “tolylene diisocyanide”, and “Puracol TP 440” is w
Yandotte chemicals is a crosslinker under the trade name.

The above components are placed in a reactor in the above order and mixed for 1 hour without external heating (unit: parts by weight).

Second stage pluracol TP 440 50 Water (contained in polyether) 0.05 After these are added, the mixture is vulcanized at 90 ° C. for 1 hour, then cooled to 60 ° C. and transferred to a storage tank. This is transferred as prepolymer to the production of the foam below.

Production of Foam Component 1 Prepolymer 100 Silicon Oil 0.5 Component 2 Jutylethanolamine 1.0 Water 1.0 puracol TP 440 31.0 Quadrol 16.0 where “Quadrol” is “tetraethylenediamine” Wyandotte chemicals is a trade name.

The two components are rapidly mixed and poured into a cardboard container.
After the foaming is completed, a curing treatment is performed at 70 ° C. for 120 minutes.
The properties of the foam after standing at room temperature for one week are shown in Table 1.

[0020]

[Table 1]

The foam thus produced has a specific gravity,
All of the tensile strength and the compressive strength can be preferably employed in the present invention.

In the present embodiment, the bead apex 9 has a cover 17 that covers the outwardly facing surface 9a and the inwardly facing surface 9b in the tire axial direction.

In the present embodiment, the cover 17 starts from a position near the outer end P of the bead apex 9 between the main body 6A of the carcass 6 and the inwardly facing surface of the folded portion 6B, in this example, beyond the outer end P. And extends around the bead core 5 and turns around the bead core 5 while passing between the folded portion 6B of the carcass 6 and the outwardly facing surface 9a.
It is arranged in a letter shape. The cover 17 is formed of a rubberized plain woven cloth and reinforces a bead portion as necessary.
The bead portion 4 may be omitted, and a chafer 19 made of a ply for reinforcing the peripheral surface thereof is provided.

[0024]

As described above, the pneumatic tire of the present invention has the following features.
By providing a bead apex made of a hard urethane material whose tensile strength and compressive strength are regulated, lateral rigidity can be increased and steering stability and riding comfort can be improved. Further, as a result of the specific gravity being much smaller than that of the rubber material, the weight of the bead apex can be reduced, and the rolling resistance of the tire can be reduced by reducing the weight of the tire, thereby reducing the fuel consumption of the vehicle.

[Brief description of the drawings]

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

FIG. 2 is an enlarged sectional view showing the bead portion.

[Explanation of symbols]

 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 6A Body part 6B Folding part 7 Belt layer 9 Bead apex 12 Hard urethane foam

Claims (2)

(57) [Claims] 1. A carcass having a folded portion which turns around a bead core of a bead portion from a tread portion through a sidewall portion, a belt layer disposed inside the tread portion and radially outside the carcass, and a main body of the carcass A pneumatic tire having a bead apex having a triangular cross section extending from the bead core outward in the tire radial direction between the portion and the folded portion, wherein the bead apex is made of a hard urethane foam material. tire. 2. The hard foamed urethane material has a specific gravity of 0.1.
20 to 0.30, a tensile strength 33~50kg / cm ^2, the pneumatic tire according to claim 1, wherein the compressive strength is 45~77kg / cm ^2.