JPH08197917A - Pneumatic tire - Google Patents

Abstract

PURPOSE: To provide a protector which prevents the occurrence of cracks and their growth while the freedom in tire design is being secured in regard to the protector to be provided for the side wall section of a tire. CONSTITUTION: In the pneumatic tire equipped with paired bead sections 2, side wall sections 3 extended in the radial direction of a tire from each bead section 2, and with a tread section laid across the side wall sections 3, a plurality of ribs 8 inclined to the circumferential direction of the tire are provided for the side walls 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to reinforcement of a sidewall of a pneumatic tire and, more particularly, to improvement of durability of the tire when hitting a stone or the like on an irregular road or when hitting a curb on a road. .

[0002]

2. Description of the Related Art Conventionally, in a vehicle running on an irregular road such as a tire for a rally, a tire having a strong carcass material is used, a side wall portion has a thick rubber gauge, or a side wall portion. Reinforcement such as inserting a reinforcement in the base part was performed. Further, recently, a tire in which several circumferential grooves are formed in a side wall portion is also known, for example, in JP-A-61-81207. By such means, stable running performance and cut resistance are improved.

These conventional tires, which are composed of grooves formed in the circumferential direction of the tire and ribs formed between the grooves, that is, a wavy protector, are provided with annular grooves in the circumferential direction of the tire. When viewed, strain concentration will occur at the bottom of the groove. On the other hand, in a general tire, the locus of the end portion of the carcass ply and the locus of the bead filler end portion both exist in the tire circumferential direction due to its structure. Due to such structural characteristics, the locus of the portion where the tire rigidity step is generated is also in the tire circumferential direction.

That is, as seen in the conventional tire shown in FIG. 7, when there is an overlap between the carcass ply end 9 or the bead filler end 10 and the groove bottom 12 of the protector 11, the strain is further reduced. It becomes easy to make the bottom portion 12. As a result, generation and growth of cracks at the bottom of the side wall protector are promoted, and further peeling occurs at the end of the carcass ply, resulting in shortened tire life and steering stability. There is a drawback that causes a problem such as a decrease in In order to prevent this, the arrangement position of the bottom portion 12,
Alternatively, the arrangement position of the carcass ply end 9 or the bead filler end 10 must be limited. An example thereof is shown in FIG.

Conventionally, such protectors have been limited to special tires used in competitions such as rallies, but in recent years,
Since the demand for RV vehicles is increasing and the number of drivers traveling in Kawahara and the like is also increasing, the demand for mounting protectors on tires for general passenger vehicles is also increasing. However, compared to a rally car, a general passenger car has a variety of suspension settings (vehicle suspension characteristics), and tire rigidity also greatly contributes to the vehicle suspension characteristics. However, it is very disadvantageous in balancing the performance of tires, and there is a large problem that the flexibility of tire design is limited.

[0006]

SUMMARY OF THE INVENTION The present invention provides a pneumatic tire having a novel protector structure that solves these problems.

[0007]

SUMMARY OF THE INVENTION The present invention provides a pneumatic tire including a pair of bead portions and a tread portion that straddles a side wall portion extending radially outward from the bead portion, The above problem is solved by providing a pneumatic tire including a plurality of ribs that are inclined with respect to the tire circumferential direction.

[0008]

Embodiments of the present invention will be described with reference to FIGS. The tires used in the following examples had the following configurations. Size: 195 / 65R15 Carcass ply: 1 piece of polyester cord rubber covered ply Belt: 2 pieces of steel cord rubber covered ply Rib width T: 5 to 6.5 mm Rib height H: 4.5 mm JIS side rubber A hardness: 50

First Embodiment First, the basic structure of the present invention will be described with reference to FIG. 1. FIG. 1 shows one half of an axial cross section of the tire of the present invention. The tire 1 includes a bead portion 2 and a tread. A carcass ply 6 as a skeleton extends inside the carcass ply end. The portion 9 is folded back around the bead core 20 and the bead filler 7 from the tire inner side to the outer side. Further, a plurality of protectors according to the present invention, that is, ribs 8 are provided on the side wall portion 3 of the tire. Furthermore, a plurality of ribs are provided also in the tire radial direction.

The structure of the rib 8 which is the protector is as follows.
The height H from the side wall surface is about 2 mm to 7 mm, and the width T on the side wall surface is also about 2 mm to 10 mm. FIG. 2 shows the outer shape of the tire. In the present invention, a plurality of ribs 8 as described above are provided so as to be inclined in one direction with respect to the tire circumferential direction from the outer circumference of the side wall portion of the tire 1 toward the inner circumference. . That is, reference numeral 13 in FIG. 2 indicates an outer start end of the rib, and reference numeral 14 indicates an inner end of the rib.
The angle θ between the tire circumferential direction and the rib 8 in this case
Can be set to any range in the range of 20 ° to 80 °. Further, E in the figure indicates the width of the portion of the side wall portion where the rib is provided. The width E can be arbitrarily set within the range of 10% to 80% of the tire cross-section height SH.

Second Embodiment FIG. 3 shows another embodiment. That is, one rib from the left side to the right side in the drawing is a rib inclined inward in the tire radial direction from the outer start end 13 toward the inner end end 14, and the other rib is also the inner start end 15 similarly. Is inclined outward in the tire radial direction from the outer end 16 to the outer end 16. The ribs 8 and 8 intersect each other at intersection points 17.

Third Embodiment FIG. 4 shows still another embodiment. In this embodiment, the angle θ between each rib 8 and the tire circumferential direction is larger than the value of θ in the second embodiment. Further, the angle θ formed between each rib and the tire circumferential direction in the second and third embodiments can be arbitrarily set within the range of 20 ° to 80 ° as in the first embodiment.

In FIG. 5, the tire 1 according to the present invention has a curb 1
8 shows the state of the protector at the time of colliding with 8.

[0014]

According to the present invention, for example, the bottom portion formed between the carcass ply end portion and the bead filler end portion and the rib of the one described in the second embodiment (this portion has a certain rigidity) The position of each rib 8 changes from left to right in the drawing from the outer circumference to the inner circumference in the tire radial direction. Do not overlap. For this reason,
The tire design does not limit the installation position of the ribs or the position of the carcass ply end 9 or the bead filler end 10 because problems such as reduction in tire life and steering stability do not occur. The degree of freedom of is large.

Further, the effects of the present invention will be compared as follows by concrete experimental data. (1) Crack growth test Test condition Size: 195 / 65R15 Internal pressure: 1.0 Kgf / cm ² Load: 480 Kgf Speed: 50 Km / h Under the above conditions, a depth of 3 mm along the bottom of the protector of the side wall, A crack with a length of 10 mm was inserted and the growth index of the crack when the drum was run for a predetermined distance was measured. (In this case, the smaller the index, the better.)

[0016]

[Table 1]

(2) Side cut test Test conditions Size: PSR195 / 65R15 Load: 480 Kgf Speed: 40 Km / h Curb height: 25 mm Curb entry angle: 30 ° (parallel to curb is 0 °) And an internal pressure of 2.0 Kgf / cm ² to 0.
The pressure was reduced every ² Kgf / cm ² and the ride on the curb was repeated, and the internal pressure when the cut was made was displayed as an index. This is the sidecut index. (In this case, the smaller the index, the better.)

[0018]

[Table 2]

As a result of this test, it was possible to make the side cut property equal to or higher than that of the conventional product. Example 2
In addition, in Example 3, the side cut property was significantly improved, and in Example 2, by disposing the protector from the vicinity of the tire maximum width to the tread portion, the weight increase due to the protector could be suppressed to a small extent.

[0020]

[Brief description of drawings]

FIG. 1 is a radial cross-sectional view of a tire of the present invention.

FIG. 2 is a side view including a partial cross section of the tire according to the first embodiment of the present invention.

FIG. 3 is a side view including a partial cross section of a tire according to a second embodiment of the present invention.

FIG. 4 is a side view including a partial cross section of a tire according to a third embodiment of the present invention.

FIG. 5 is a schematic view showing a state in which the tire of the present invention collides with a curb on a road.

FIG. 6 is a partial cross-sectional view of a conventional tire having a circumferential groove for a protector.

FIG. 7 is a radial cross-sectional view showing a positional relationship between a groove bottom portion, a carcass end portion, and a bead filler end portion of a conventional tire having a circumferential groove for a protector.

[0021]

[Explanation of symbols]

 1 tire 2 bead part 3 sidewall part 8 rib 10 bead filler end part 11 protector

Claims (1)

[Claims] 1. A pneumatic tire comprising a pair of bead portions, a sidewall portion extending radially outward from the bead portion, and a tread portion straddling the sidewall portion, wherein the tire is inclined with respect to the tire circumferential direction. A pneumatic tire having a plurality of ribs on the outer surface of the sidewall.