JPH0966708A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the possibility of groove bottom damaging caused by a foreign body on a road without reducing the high draining performance of a wide main groove. SOLUTION: In a pneumatic tire having a wide main groove 2 with a groove width A larger than a groove depth B provided in a tread surface 1 in the tire peripheral direction T, one or more projections 4 are provided in the groove bottom of the main groove 2 so as to be extended along the main groove 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly, to a tire having a main groove having a groove width larger than a groove depth, which is suitable for a passenger car, in which puncture is reduced. Regarding pneumatic tires.

[0002]

2. Description of the Related Art Recently, in order to further improve the drainage performance (wet performance) of a pneumatic tire for passenger cars, the groove width A of the main groove in the tire circumferential direction provided on the tread is as shown in FIG. It has been proposed that the groove depth be made larger than B. However, since a tire with a wide main groove has a large groove width, it is more likely that foreign matter such as metal pieces and pebbles on the road surface will be attracted to the groove bottom to directly damage the groove bottom, and punctures will easily occur. There was a problem.

Conventionally, as a measure for preventing stone trapping, it has been proposed to provide a shelf-like projection on the side wall of the main groove. However, since it is provided on the side wall, the groove width is narrowed, and when this is applied to the tire with the wide main groove as described above, not only is the drainage performance of the wide groove reduced, but also the foreign matter elimination effect is not necessarily good. It didn't bring any results.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to prevent damage to the bottom of a wide main groove, which is a drawback of the wide main groove, and to reduce puncture without reducing the high drainage performance of the wide main groove. It is to provide a pneumatic tire.

[0005]

The pneumatic tire of the present invention which achieves the above object is a pneumatic tire having a wide main groove having a groove width equal to or larger than a groove depth in a tire circumferential direction on a tread surface. One or more projections extending along the main groove are provided on the bottom of the main groove. By providing one or more projections extending along the main groove on the groove bottom in this way, the probability of attracting foreign matter on the road surface to the groove bottom and directly damaging the groove bottom is reduced, and puncture occurs. It can be difficult. Further, since the projection is provided on the groove bottom, the drainage performance by the wide main groove is not reduced.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be specifically described below with reference to the embodiment shown in the drawings. FIG.
(A), (b) and FIG. 2 show an example of a main groove provided so as to extend in the tire circumferential direction on the tread surface of the pneumatic tire of the present invention. As shown in FIG. 2, the main groove 2 provided on the tread surface 1 has a groove width A equal to or larger than a groove depth B (A ≧
The width is wide as shown in B), and may be linear along the tire circumferential direction T as shown in FIG. 1A, or may be zigzag as shown in FIG. 1B. One to three main grooves 2 are provided for the tread surface 1. One protrusion 4 is provided at the bottom of each main groove 2 along the longitudinal direction of the main groove 2. The number of protrusions 4 provided on the bottom of the groove is the same as those in FIGS.
It may be two or more as shown in FIG.

The pneumatic tire having the above-mentioned structure is
Since the groove width A of the main groove 2 is larger than the groove depth B, the drainage performance of the tire can be improved. Further, since the main groove 2 has a wide width, foreign matter can easily enter, but since the protrusion 4 is provided on the groove bottom, it is pushed back to the outside before reaching the groove bottom and is likely to be damaged by directly hitting the groove bottom. To reduce. Further, even if foreign matter is caught, it can be easily removed by the vibration of the protrusion 4 during traveling, and since the protrusion 4 is provided at the groove bottom, the drainage performance based on the wide main groove 2 is extremely high. It will not be reduced.

In the present invention, the cross-sectional shape of the projection is not particularly limited, but it is preferably a mountain shape as shown in the figure, the upper end is arcuate, and the longitudinal direction is along the main groove. It is preferable to be continuous, but there may be a discontinuous portion as long as it is a short distance of 10 mm or less.
In order to make the effect based on the above-mentioned protrusion more remarkable,
The height H and the width D in the cross section of the protrusion are the same as the height H regardless of whether the number of protrusions set is one or plural.
Is in the range of (0.15-0.25) B with respect to the main groove depth B, and the width D is (0.20-0.3) with respect to the groove bottom width E of the main groove.
5) It is good to set it in the range of E. However, when the number of protrusions installed is two or more, the total width D of the protrusions is 0.
It is desirable to set it to 80E or less.

When the height H and the width D of the protrusions are less than the lower limit values, the effect of discharging foreign matter from the main groove and the effect of preventing the groove bottom from being directly damaged by foreign matter on the road surface can be sufficiently achieved. Disappear. Further, when the height H and width D of the protrusions are larger than the upper limit values, the drainage amount by the main groove is reduced, so that the drainage performance is deteriorated. Since the tip is exposed early, the running performance and braking performance are adversely affected.

The height H and the width D of the protrusions do not necessarily have to be the same in the longitudinal direction regardless of whether the number of protrusions is one or a plurality, and may be varied. When a plurality of protrusions are provided, their height H and width D may be different from each other. In the present invention, the width D of the protrusion means the distance between the intersections of the extension lines of the left and right side walls and the extension line of the main groove bottom, and the groove bottom width E of the main groove is the extension line of both side walls of the main groove. Is the distance between the intersections of the intersections with the groove bottom extension lines.

[0011]

[Embodiment] The tire size is 205 / 65R15, and it is common that two linear main grooves having a groove width of 15 mm, a groove depth of 10 mm and a groove bottom width of 9.5 mm are provided on the tread surface. Tires 1 to 3 of the present invention in which the number of protrusions provided on the groove bottom of the main groove and the cross-sectional dimensions (height H, width D) were made different as shown in Table 1 and conventional tires were manufactured.

[0012] These test tires were mounted on a rim with a rim size of 6J × 15, the air pressure was 200 kPa, and the displacement was 2000 c.
Installed four each on a passenger car of c, 2000km, 4000km, 6000km, 8000km on a general paved road with full load
Immediately after running 10000 km, the number of scratches on the bottom of the main groove of the tire was visually measured to obtain the tire 1
The average value per book was evaluated.

As a result, the evaluation result as shown in the graph of FIG. 5 was obtained. As is clear from FIG. 5, in all of the tires 1 to 3 of the present invention, the damage to the bottom of the main groove is significantly reduced as compared with the conventional tire.

[0014]

The pneumatic tire of the present invention has a structure in which the groove width of the main groove provided on the tread surface is equal to or larger than the groove depth, and a protrusion extending along the main groove is formed at the bottom of the main groove. By providing more than this number, damage due to foreign matter on the road surface can be reduced, so that occurrence of puncture can be reduced. Further, since the protrusion is provided on the groove bottom, the drainage performance based on the wide main groove is not significantly impaired.

[Brief description of drawings]

1 (a) and 1 (b) are plan views showing essential parts of an example of a main groove provided on a tread surface of a pneumatic tire of the present invention.

FIG. 2 is a sectional view taken along line FF of FIGS. 1 (a) and 1 (b).

FIG. 3 is a cross-sectional view showing a main groove provided on a tread surface of a pneumatic tire according to another embodiment of the present invention.

FIG. 4 is a sectional view showing a main groove provided on a tread surface of a pneumatic tire according to still another embodiment of the present invention.

FIG. 5 is a graph showing a relationship between a traveling distance and the number of groove bottom scratches per tire.

FIG. 6 is a cross-sectional view showing an example of a main groove provided on a tread surface of a conventional pneumatic tire.

[Explanation of symbols]

 1 tread surface 2 main groove 4 protrusion A groove width B groove depth T tire circumferential direction

Claims (3)

[Claims] 1. A pneumatic tire in which a wide main groove having a groove width equal to or larger than a groove depth is provided on a tread surface in a tire circumferential direction,
A pneumatic tire having one or more protrusions extending along the main groove on the bottom of the main groove. 2. The pneumatic tire according to claim 1, wherein two or more protrusions are provided, and adjacent protrusions have different heights. 3. The pneumatic tire according to claim 1, wherein the height of the protrusion is changed along the tire circumferential direction.