JPH05286419A - Stone bite preventive structure for tire - Google Patents

Abstract

PURPOSE:To prevent a stone bite by forming a projection, which is projecting from the bottom surface, on the bottom of a lug groove arranged on a tire, and forming a structure so as to push out a stone bitten in the lug groove by means of this projection. CONSTITUTION:A large number of lug grooves 4 being widened gradually from the vicinity of the tread center S to a shoulder part 3 are formed on a tire, and a projection 5 projecting from the bottom surface 4A of the lug groove 4 is provided. The projection 5 is formed in the center of groove width on the bottom surface 4A of the lug groove, and a cross sectional shape is a square shape, and the width TW is set to be about 30-50% the width MW of the lug groove 4. The length TL of the projection 5 is formed in about 30% of the length ML of the lug groove 4, and the height of the projection 5 is formed in 10-40 of the depth of the lug groove. In the above-mentioned structure, if a stone bites in the lug groove 4 while traveling, since there exists the projection 5, the stone does not reach the bottom surface 4A, so that a deep bite can be prevented, and even if the projection 5 is pressed by the biting stone, the stone is pushed out from the lug groove 4 due to the restoring force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stone trapping structure for a tire having a lug pattern used for trucks, buses and the like.

[0002]

2. Description of the Related Art In tires for heavy vehicles such as trucks, a lug pattern is formed in a tire tread portion in order to increase driving force and braking force, and a lug groove has a wide groove width.
It is easy to bite stones. The tire tread portion has the highest ground contact pressure and is likely to be damaged, and if stones are caught in the lug groove of the tread portion, cracks may occur from the groove bottom. In order to prevent this, the wall thickness of the tread portion is increased, and the rubber composition of the tread portion is made to have excellent cut resistance.

[0003]

In the above-mentioned prior art, when the wall thickness of the tread portion is increased or the rubber composition is changed, the heat generation of the tread portion becomes high, the tread separation is likely to occur, and stone entrapment occurs. As a preventive measure, it is hard to say that it is good. The present invention is
It is an object of the present invention to provide a stone trapping prevention structure for a tire that can easily solve the problems of the conventional art by forming a protrusion protruding from the bottom surface on the bottom of the lug groove.

[0004]

The first specific means for solving the problems in the present invention is the center S of the tread portion 2.
In a tire having a rug pattern in which a lug groove 4 is formed from the side to the left and right shoulder portions 3, a protrusion 5 protruding from the bottom surface (4A) is formed on the bottom of the lug groove 4.

A second specific means for solving the problem in the present invention is that in addition to the first specific means, the projection 5 has a lug groove length ML of 2 from the end of the lug groove 4 on the tread center S side.
It is formed to have a length TL equal to or more than 40% and a height TH which is 10 to 40% of the lug groove depth MH from the lug groove bottom surface 4A. A third specific means for solving the problem in the present invention is that, in addition to the first specific means, the projection 5 is formed at the center of the lug groove bottom surface 4A in the groove width direction.

A fourth specific means for solving the problem in the present invention is that, in addition to the first specific means, a pair of protrusions 5 are formed separately on both sides of the lug groove bottom surface 4A in the groove width direction. Is. A fifth specific means for solving the problem in the present invention is that, in addition to the first specific means, the protrusion 5 is formed to be gradually lower from the tread center S side of the lug groove 4 to the side side. ..

A sixth concrete means for solving the problems in the present invention is that, in addition to the first concrete means, the projection 5 is formed continuously or intermittently in the longitudinal direction of the lug groove 4. is there.

[0008]

When the stone 7 enters the lug groove 4 during traveling, the protrusion 7 is formed on the bottom of the lug groove 4, so that the stone 7 does not reach the bottom surface 4A and floats in the air, resulting in deep biting. Moreover, the stones 7 that have entered are pressed against the protrusions 5, and the restoring force of the protrusions 5 pushes the stones 7 out of the lug groove 4.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. In the first embodiment shown in FIGS. 1 to 3, the tire 1 has a lug pattern formed on the tread portion 2, and the lug grooves 4 gradually widened from the vicinity of the tread center S to the shoulder portion 3 are arranged at equal intervals in the circumferential direction. A large number of lugs 8 are formed, and lugs 8 are formed between the lug grooves 4. The two-dot chain line in FIG. 1 is the lug groove 4.
It shows a stone that has been bitten into.

The lug groove 4 is gradually narrowed toward the bottom, and a protrusion 5 protruding from the bottom surface 4A is formed on the bottom. The protrusion 5 is formed at the center of the lug groove bottom surface 4A in the groove width direction and has a rectangular cross section, and the width TW is about 30 to 50% of the width MW of the lug groove 4. If the width TW of the protrusion 5 is narrower than 30%, it is easily damaged by the stone 7.
If it is wider than half, the function of the lug groove 4 is deteriorated.

The length TL of the protrusion 5 is about 30% of the lug groove length ML from the end of the lug groove 4 on the tread center S side, and is formed continuously in the longitudinal direction of the lug groove 4. ing. The protrusion length TL may be formed to be about 10 to 100% of the lug groove length ML, preferably 20% or more, and when it is 20% or less, cut resistance on the tread center S side. Is hard to expect.

The height TH of the projection 5 is determined by the lug groove bottom surface 4
It is formed at a height of 10 to 40% of the lug groove depth MH from A, and is formed gradually lower from the tread center S side of the lug groove 4 to the side side. If the height TH of the protrusion 5 is lower than 10%, the stone trapping effect is low, and if it is higher than 40%, the traction is reduced and the protrusion 5 may be damaged.

In the second embodiment shown in FIGS. 4 to 6, a protrusion 5 protruding from the bottom surface 4A at the center of the lug groove 4 in the groove width direction is formed over substantially the entire length of the lug groove ML. The cross-sectional shape, height TH and width T of this protrusion 5
W and the like are the same as in the first embodiment. The projections 5 of the second embodiment are formed intermittently in the longitudinal direction, and when compressed by stones, they are not only deformed by compression but also easily deformed in the tire circumferential direction and the width direction. Since it is easily deformed greatly, reduction of traction can be suppressed.

In the third embodiment shown in FIGS. 7 to 9, a pair of protrusions 5 are formed on the bottom of the lug groove 4 so as to be spaced apart from both sides of the bottom surface 4A in the groove width direction. The protrusion 5 is integrated with the side wall of the lug groove 4 and has a length that is approximately half the lug groove length ML. The cross-sectional shape of each protrusion 5 is square and has substantially the same height over its entire length. The protrusion 5 of the third embodiment projects from the corner portion of the bottom surface 4A of the lug groove 4 and the side wall to the center of the groove.
As in the case of the second embodiment, it is possible to prevent stones from being caught, and it is possible to more reliably prevent the groove bottom from being cut.

The fourth embodiment shown in FIG. 10 is one in which the projection 5 of the third embodiment is intermittently formed in the longitudinal direction.
Deformation is made easier than that of the protrusion 5 of the embodiment, the effect of trapping stones is increased, and the reduction of traction is suppressed.

[0016]

[Experimental Example] An experimental example will be described with reference to FIGS. FIGS. 10 and 11 are the same as the tire 1 of the first embodiment, and simultaneously show projections 5a, 5b, 5c, and 5d of four types of lengths, and each projection 5 has a projection width TW and a lug groove width. M
About 2.5% of W, projection height TH is 2 of lug groove depth MH
It is set to around before and after.

The protrusion 5a has substantially the same length as the length of the lug groove 4 and has a uniform height over the entire length, and the protrusion 5b has substantially the same length as the length of the lug groove 4 and the height becomes lower toward the shoulder portion 3, The protrusion 5c is about 30% of the length of the lug groove 4 and is gradually lowered, and the protrusion 5c is about 10% of the length of the lug groove 4 and is gradually lowered. When the tire 1 of the present invention having the protrusions 5a, 5b, 5c, and 5d and the conventional tire having no protrusion 5 were run on the road, the results shown in Table 1 were obtained. The traction performance of a conventional tire having no protrusions 5 and the rate of occurrence of groove bottom cut of the lug groove 4 due to stone entrapment are set to 100.

The traction performance of the tire 1 having the protrusions 5a, 5b, 5c and 5d is 1 to 3 as compared with the conventional tire.
It decreases about 0 points and the traction performance decreases due to the presence of the protrusion 5, but the groove bottom cut occurrence rate is 30 to 95.
It is clear that the number of points is decreased, and by providing the projections 5 that are small and short, stones can be prevented from being caught and the occurrence of groove bottom cutting can be suppressed.

Looking at the projections 5c, the traction performance is reduced by only 2 points compared to the conventional tire, but the groove bottom cut occurrence rate is decreased by 90 points. If about 10 points are allowed, it is possible to exhibit traction performance comparable to that of conventional tires.

[0020]

[Table 1]

The present invention is not limited to the above embodiment, but can be variously modified. For example, first to
The combination of the cross-sectional front shape, the cross-sectional side surface shape, the plane shape, etc. of the projection 5 of the third embodiment may be changed, and the cross-sectional side surface shape of the projection 5 may be trapezoidal, semi-circular, etc. When arranged, one shoulder portion 3 may be formed to have a length exceeding the tread center S, and the lug grooves 4 may have the same width in the longitudinal direction and the same width in the depth direction, or may be bent halfway in the longitudinal direction. May be.

[0022]

According to the present invention described in detail above, the lug groove 4 is provided.
Since the protrusion 5 protruding from the bottom surface 4A is formed on the bottom of the base, it is possible to prevent stones from being caught by the protrusion 5 and to reduce the groove bottom cut occurrence rate of the lug groove 4.

[Brief description of drawings]

FIG. 1 is a sectional side view of an essential part showing a first embodiment of the present invention.

FIG. 2 is a front view of the same section.

FIG. 3 is a plan view of the same.

FIG. 4 is a sectional side view of a main part showing a second embodiment of the present invention.

FIG. 5 is a front view of the same section.

FIG. 6 is a plan view of the same.

FIG. 7 is a sectional side view of a main part showing a third embodiment of the present invention.

FIG. 8 is a front view of the same section.

FIG. 9 is a plan view of the same.

FIG. 10 is a plan view showing a fourth embodiment of the present invention.

FIG. 11 is a plan view for explaining an experimental example of the present invention.

FIG. 12 is a front view of the same section.

[Explanation of symbols]

 1 tire 2 tread portion 3 shoulder portion 4 lug groove 4A bottom surface 5 protrusion S tread center ML lug groove length TL protrusion length MH lug groove depth TH protrusion height MW lug groove width TW protrusion width

Claims (6)

[Claims] 1. A tire having a rug pattern in which a lug groove (4) is formed from the center (S) side of the tread portion (2) to the left and right shoulder portions (3), and a bottom surface (4A) is formed on the bottom of the lug groove (4). ) Is formed with a protrusion (5) which is raised from (1). 2. The protrusion (5) is formed to have a length (TL) of 20% or more of the lug groove length (ML) from an end of the lug groove (4) on the tread center (S) side, and the lug groove (5) is formed. Bottom (4A)
2. The stone trapping prevention structure for a tire according to claim 1, wherein the structure is formed to have a height (TH) that is 10 to 40% of the lug groove depth (MH). 3. The tire stone entrapment prevention structure according to claim 1, wherein the protrusion (5) is formed at the center of the bottom surface (4A) of the lug groove in the groove width direction. 4. The stone trapping structure for a tire according to claim 1, wherein a pair of the projections (5) are formed on both sides of the bottom surface (4A) of the lug groove in the groove width direction. 5. The prevention of stone trapping in a tire according to claim 1, wherein the protrusion (5) is formed so as to be gradually lowered from the tread center (S) side of the lug groove (4) to the side side. Construction. 6. The stone trapping structure for a tire according to claim 1, wherein the protrusions (5) are formed continuously or intermittently in the longitudinal direction of the lug groove (4).