JP2003205713A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve road noise and riding comfort. <P>SOLUTION: Annular bead cores 3 are disposed on a bead part 2 of a pneumatic tire. The bead cores 3 has tube core parts 3B formed by winding tubular bodies 7 with the liquid or gas sealed inside thereof. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a pneumatic tire having an improved bead core.

[0002]

2. Description of the Related Art An annular bead core is embedded in the bead portion of a pneumatic tire. This bead core maintains the bead diameter and firmly seats the bead portion on the rim. Many common bead cores are formed by winding a single steel wire in multiple stages and multiple rows.Some of them are also known to be formed by using a highly elastic cord such as aramid for the purpose of weight reduction. ing.

The inventors have made various attempts to improve such bead cores. Then, it has been found that when a bead core is provided with a tube core portion formed by winding a tube body in which a liquid or gas is sealed, the road noise performance and the riding comfort are improved.

As described above, it is an object of the present invention to provide a pneumatic tire that is useful for improving road noise performance and riding comfort, based on the provision of the tube core portion on the bead core.

[0005]

The invention according to claim 1 of the present invention is a pneumatic tire in which an annular bead core is arranged in a bead portion, the bead core having a liquid or gas sealed therein. It is characterized by having a tube core portion formed by winding a tube body.

The bead core may be composed of a steel core portion formed by winding a steel wire and the tube core portion. In this case, it is preferable that the tube core portion be the innermost layer portion of the bead core in the tire radial direction.

Further, the tube core portion preferably has a total cross-sectional area of 10 to 30% of the total cross-sectional area of the bead core. The tube body is preferably sealed with an inert gas or a lubricant inside, and the tube body can be made of, for example, a resin or a metal material.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an enlarged cross-sectional view of a bead portion of a pneumatic tire for passenger cars (not shown), and FIG. 2 is an enlarged view of a bead core. In the figure,
The bead portion 2 is provided with an annular bead core 3 and, in this example, a bead apex 4 that is tapered from the outer surface of the bead core 3 in the tire radial direction. The carcass ply 5 forming the skeleton of the tire is folded around the bead core 3 from the inner side in the tire axial direction to the outer side and locked.

The bead core 3 in this example is formed by winding a steel wire 6 into a steel core portion 3
An example is one including A and a tube core portion 3B formed by winding a tube body 7 in which a liquid or gas is sealed.

In the steel core portion 3A, a single wire steel wire 6 having a circular cross section is multistage and multirow, in this example, 5 rows ×
The cross-section is formed into a horizontally long rectangular shape by winding in three stages. When winding the steel wire 6, 1
It is also possible to continuously wind one steel wire, or to form a wire bundle in which five steel wires are arranged side by side in the width direction and bundled in a tape shape in a spiral shape,
The form is not particularly limited. The steel core part 3A
In addition to the wound steel wire 6, for example, a steel material having the laterally long cross-sectional shape may be used.

The tube core portion 3B is a tube body 7
And a tape-shaped one formed by winding the tube body 7 in five rows and one stage.

As shown in an enlarged view in FIG. 3, for example, the tube body 7 is composed of a cylindrical portion 7a having a cylindrical outer peripheral surface and end face wall portions 7b closing both ends of the cylindrical portion 7a. A long material is used. A hollow portion 9 that is a substantially closed space is formed in the tube body 7, and a gas or a liquid (both of them can be contained together) is sealed in the hollow portion 9. Such a tube body 7 is
For example, as shown in FIG. 5 (A), the tube core portion 3B can be formed by continuously spirally winding while shifting the position in the axial direction. When the tube body 7 is wound, it is desirable that thin unvulcanized rubber be attached to the outer peripheral surface of the tube body 7.

Further, as shown in FIG. 4, the tube body 7 may be previously formed as an annular body continuous in an annular shape.
In this case, as shown in FIG. 5B, the tube core portions 3B can be configured by arranging the annular tube bodies 7 side by side in the width direction and appropriately bundling them.

Further, the tube body 7 is not particularly limited as long as its shape can be substantially retained inside the bead portion 2 and the strength is such that large plastic deformation or breakage does not occur. Materials can be used. As an example, it can be made of a metal material or a resin material. As the metal material, for example, iron, stainless steel, copper, copper alloy, aluminum, brass and the like are suitable, and as the resin material, polystyrene, PET, acrylic resin, vinyl chloride, nylon, polycarbonate, fluororesin, polyamide, polyethylene, polypropylene. , ABS resin,
Polyphenylene ether and the like are preferable.

Gas or liquid is sealed inside the tube body 7 as described above. As a result, the weight of the bead core 3 can be reduced. Further, the tube body 7 has a hollow inside unlike the steel wire 6 of the steel core portion 3A, so that the tube core portion 3 may be affected by a load during traveling.
B flexes moderately. As a result, riding comfort and road noise performance can be improved. As a result of various experiments by the inventors, when the gas is sealed inside the tube body 7, the riding comfort is mainly improved, and when the liquid is sealed, the road noise performance is large. It turned out to be effective. Although the mechanism is not clear, it is presumed that the ride comfort is due to the elastic deformation of the tube body 7 absorbing and relaxing the vibration during traveling and interrupting the transmission to the rim. Further, regarding the improvement of the road noise performance, the liquid sealed inside the tube body 7 efficiently absorbs the vibration component due to the fixed propagation that is most likely to affect the road noise performance and propagates it to the rim or the vehicle interior. It is presumed that this was due to the inhibition.

The gas to be sealed inside the tube body 7 is not particularly limited, but as a result of various experiments, it is necessary to prevent nitrogen, which has a great effect on ride comfort, and to prevent deterioration of durability due to oxidation or the like. An inert gas such as argon or helium is suitable.

The liquid to be sealed in the tube body 7 is not particularly limited, but a lubricant such as process oil has been particularly effective in improving the road noise performance. In this case, it is preferable to use an oil resistant material for the tube body 7. In addition to the lubricant, a liquid such as silicone oil can be sealed. In this case, deterioration of durability due to aging can be prevented. The rigidity and elasticity of the tube body 7 can be adjusted as appropriate by changing the filling pressure of the gas or liquid sealed in the tube body 7.

Further, the tube core portion 3B of this embodiment is
It is arranged inside the steel core portion 3A in the tire radial direction and forms the innermost layer portion of the bead core 3 in the tire radial direction. By forming the tube core portion 3B having a high impact absorption and noise absorption effect in the innermost layer portion of the bead core 3 as described above, it is possible to effectively prevent vibration or noise from being transmitted to the rim, the vehicle body or the like. Therefore, it is useful for further improving the riding comfort and road noise performance.

Although not particularly limited, it is preferable that the total cross-sectional area Sa of the tube core portion 3B is 10 to 30%, more preferably 20 to 25% of the total cross-sectional area S of the bead core 3. If the total cross-sectional area Sa of the tube core portion 3B is less than 10% of the total cross-sectional area S of the bead core 3, the effect of improving the riding comfort and road noise performance tends to decrease, and conversely exceeds 30%. Then, the strength required for the bead core 3 tends to decrease, and the durability tends to deteriorate. The total cross-sectional area Sa of the tube core portion 3B is
Is the total cross-sectional area surrounded by the outer peripheral surface of the tube body 7,
The total cross-sectional area S of the bead core is the total cross-sectional area Sa of the tube core portion 3B plus the total cross-sectional area of the steel core portion 3A. The total cross-sectional area of the steel core portion 3A is the sum of the step areas surrounded by the outer peripheral surface of the steel wire 6.

Although one embodiment of the present invention has been described in detail above, for example, the bead core 3 can be formed in a circular shape or a polygonal shape in addition to the rectangular cross section. In addition, FIG.
As shown in (B), the tube core portion 3B may be provided in the middle layer portion or outer layer portion of the bead core in the tire radial direction. Furthermore, when the strength is satisfied, the present invention can be implemented in various modes, such that the bead core 3 can be composed of only the tube core portion 3B.

[0021]

[Example] A pneumatic tire for passenger cars having a tire size of 215 / 45ZR17 was prototyped based on the specifications of Table 1, and steering stability, riding comfort, and road noise performance were tested to compare the performances. The structure was the same except for the bead core. In the conventional example, a bead core wound in 5 rows × 4 stages as shown in FIG. 2 was used using only a single wire steel wire having an outer diameter of 1.2 mm. In addition, in each of Examples 1 to 5, a tube body made of a metal material (material: stainless steel) was used. As a common specification, the tube body has an outer diameter of 1.2 mm and an inner diameter of 0.8 mm.
And In Examples 1 and 2, nitrogen gas was sealed inside, and in Examples 3 and 5, process oil was sealed. In Examples 2 and 5, as shown in FIG. 6 (A), the second and third stages are tube core portions, and in Example 4, the outermost layer is a tube as shown in FIG. 6 (B). The core part. The test procedure is as follows.

<Driving stability and riding comfort> Test tire 17
* 7-JJ aluminum wheel rim assembled on rim for air pressure 2
It was filled with 30 kPa and mounted on all wheels of a domestic FR car with a displacement of 2000 cm ³ , and a sensory evaluation was conducted by driving one driver on the test course. The evaluation is performed by a 10-point method with the conventional example being 6, and the larger the value, the better.

<Road Noise Performance> Using the above vehicle, the noise when running on a dry asphalt road surface at a speed of 50 km / h was measured by a microphone installed in the right ear of the driver's seat, and the noise difference with the conventional example as a reference value was measured. Was evaluated by db (A). Minus display is good. Table 1 shows the test results and the like.

[0024]

[Table 1]

As a result of the test, it can be confirmed that the vehicle of the embodiment improves the riding comfort and road noise performance while maintaining the steering stability as compared with the conventional example.

[0026]

As described above, in the pneumatic tire of the present invention, since the bead core has the tube core portion, riding comfort and road noise performance can be improved while maintaining steering stability.

According to a second aspect of the present invention, the bead core has a steel core portion formed by winding a steel wire and the tube core portion, and the tube core portion has a bead core tire radius. When forming the innermost layer in the direction, in order to effectively absorb the vibration input from the tread and make it difficult to be transmitted to the rim,
The riding comfort and road noise performance can be further improved.

According to the third aspect of the invention, the total cross-sectional area of the tube core portion is 10 to 3 of the total cross-sectional area of the bead core.
When it is limited to 0%, the riding comfort and road noise performance can be improved more reliably without causing deterioration of durability.

When the tube body seals the inert gas or the lubricant as in the invention described in claim 4,
The riding comfort and road noise performance can be further improved.

[Brief description of drawings]

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

FIG. 2 is an enlarged sectional view of a bead core.

FIG. 3 is an exploded perspective view showing an example of a tube body.

FIG. 4 is an exploded perspective view showing another example of the tube body.

5A and 5B are schematic views illustrating a method for forming a tube core portion.

6 (A) and 6 (B) are sectional views of a bead core showing another embodiment of the present invention, and FIG. 6 (C) shows a bead core of a conventional example.

[Explanation of symbols]

2 bead part 3 bead core 3A Steel core part 3B tube core 6 Steel wire 7 tube body 9 Hollow part

Claims (5)

[Claims] 1. A pneumatic tire in which an annular bead core is arranged in a bead portion, wherein the bead core has a tube core portion formed by winding a tube body in which a liquid or gas is sealed. Pneumatic tire characterized by. 2. The bead core includes a steel core portion formed by winding a steel wire and the tube core portion, and the tube core portion is an innermost layer portion of the bead core in a tire radial direction. The pneumatic tire according to claim 1, wherein the pneumatic tire is formed. 3. The pneumatic tire according to claim 1 or 2, wherein the tube core portion has a total cross-sectional area of 10 to 30% of a total cross-sectional area of the bead core. 4. The pneumatic tire according to claim 1, wherein the tube body is sealed with an inert gas or a lubricant. 5. The pneumatic tire according to claim 1, wherein the tube body is made of a resin or a metal material.