JP2000177329A - Tire tread - Google Patents

Abstract

PROBLEM TO BE SOLVED: To balance the rigidity increase of a projection element by the progress of wear to keep satisfactory ice and snow road performance to the latter half of the wear by forming a sipe on a corrugated or broken line in the depth direction, and forming the corrugated or broken line so that the amplitude thereof is reduced toward the depth direction. SOLUTION: In a tire tread 1 having a projection element 4 having an opened sipe 9 formed on a tread surface 1A, the sipe 9 is formed on a corrugated or broken line in the depth direction (tire radial direction). The corrugated or broken line is formed so that the amplitude A thereof is reduced toward the depth direction. Although the projection 4 is gradually worn by the friction with a road surface, and the projection height is reduced to enhance the rigidity, the contact between the sipe walls is minimized according to this to reduce the rigidity keeping force by the wall surface contact, whereby the rigidity increase by the progress of wear is cancelled, and satisfactory ice and snow performance can be kept to the latter half of the wear.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire tread, and more specifically, to a projection element (referred to as a rib or a block) forming a sipe opening on the tread surface.
The tire tread comprises:

[0002]

2. Description of the Related Art A tire tread, particularly a tread of a studless tire, is constituted by a projection element forming a sipe opening on the tread surface. By forming the sipe, the rigidity of the projection element is reduced. Good icy and snowy road performance is obtained (with appropriate rigidity as a studless), and sipe edge components are increased and a water film is removed (see JP-A-59-199306, JP-A-6-143942, etc.). .

[0003]

When the tire is mounted on an automobile and the vehicle travels on an icy road or the like, the tire tread gradually wears due to friction with the road surface, and the height of the projection element gradually decreases. Therefore, the rigidity of the projection element gradually increases.

In the conventional sipe, a portion opening on the tread surface is formed as a linear opening or a wavy (zigzag) opening, and there is no amplitude or a constant amplitude even in the depth direction of the sipe. And it was.

For example, in the sipe shape disclosed in Japanese Patent Laid-Open No. 6-143942, the first half of the sipe is formed in a straight line (perpendicular to the tread surface) in the depth direction, and the second half has a waveform having a constant amplitude. By being sipes,
It was intended to prevent cracks at the sipe bottom.

However, as described above, the tire tread gradually wears, and the rigidity of the projection element gradually increases. Therefore, in a waveform sipe having a constant amplitude, the rigidity due to the progress of wear is increased. It was difficult to maintain good ice and snow performance until the latter half of the wear by offsetting the increase in the snow.

The sipe shape disclosed in Japanese Unexamined Patent Publication No. 59-199306 is a sipe having a wave-shaped opening, and although the sipe has a small amplitude at the bottom surface, the sipe wall surfaces are not connected to each other. The contact was almost constant even with the progress of wear, and it was therefore difficult to offset the increase in rigidity.

Therefore, in the present invention, the amplitude of the sipe waving in the depth direction is reduced in the depth direction to reduce the contact between the sipe wall surfaces with the progress of wear, that is, the wall contact. It is an object of the present invention to provide a tire tread capable of maintaining good ice / snow road performance until the latter half of wear by offsetting an increase in rigidity of a projection element due to progress of wear by reducing a force for maintaining rigidity due to wear.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a tire tread 1 having a projecting element 4 forming a sipe 9 opening in a tread surface 1A. Have taken strategic steps.

That is, in the present invention according to claim 1, the sipe 9 is formed in a waveform or a polygonal line in the depth direction, and the amplitude A of the waveform or the polygonal line is formed to become smaller as it reaches the depth direction. It is characterized by having.

By adopting such a configuration, when the tire is mounted on a car and the vehicle runs on an icy and snowy road, the vehicle travels without slipping into the frozen film or the like due to the edge of the sipe 9 opening on the tread surface 1A. It is possible.

The projection element (4) gradually wears due to friction with the road surface and gradually increases in rigidity as the projection height decreases, but the amplitude A of the sipe 9 decreases as the depth increases. The wall 9- of the sipe 9
Since the contact between A and 9-B is reduced and the force for maintaining the protrusion rigidity due to the wall contact is reduced, the increase in the protrusion rigidity due to the progress of wear can be offset, and good ice and snow road performance can be maintained until the latter half of wear. is there.

Here, the form of the sipe 9 may be any one of a closed sipe, an open sipe, a one-sided open sipe, and a semi-open, and the projecting element 4 is a shoulder block, a center side block, a rib, or the like. In short, any pneumatic tire of studless (without spike pins) may be used.

In the present invention, the amplitude A of the sipe 9 is
Is desirably composed of three types of large, medium and small A1, A2, A3 (Claim 2). The sipe 9 has a zero amplitude portion 9-4 on the bottom side thereof, It is desirable to form the sipe bottom portion 9-5 extending in the straight direction in the vertical direction (claim 3).

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

Referring to FIG. 1, a tire tread 1 exemplified by a block pattern has a projection element 4 exemplified by a shoulder block 3 arranged in parallel with a lateral groove 2 in a circumferential direction of the tire, and It is provided with a projection element 4 exemplified by a side block 6 juxtaposed in the tread width direction via a vertical groove 5.

Although the projection elements 4 are shown as square blocks in the figure, they may be so-called caramel blocks or ribs (rib / block pattern). May be a linear groove or a so-called zigzag groove. In FIG. 1, reference numeral 7 denotes a tread ply (belt layer), and reference numeral 8 denotes a carcass ply.

The projection element 4 has a sipe 9 formed in the tread surface 1A. The sipe 9 may be in the form of a closed sipe 9A shown in FIG.
, A semi-closed sipe 9C shown in FIG. 4C, and a one-sided open sipe 9D shown in FIG. 4D.

The opening direction of the sipe 9 opening on the tread surface 1A of the projection element 4 may be in the lateral direction (perpendicular to the tire rotation direction) as exemplified by the shoulder block in FIG. A vertical direction (parallel to the tire rotation direction) as illustrated by a block, or an oblique direction (not shown) may be used, and the opening direction may be any of the illustrated linear form or zigzag form, and the size of the block. Although it depends on the like, a plurality of sipes 9 are engraved on the tread surface 1A of one projection element 4.

The sipe 9 is formed in a waveform or a polygonal line in the depth direction (radial direction of the tire), and the amplitude A of the waveform or the polygonal line becomes smaller as it goes in the depth direction.

In FIG. 2, the waveform is arc-shaped,
In FIG. 3A, the displacement portions 9-1, 9-2, and 9-3 are circular arcs, and the displacement portions 9-1, 9-2, and 9-3 are linear. Large, medium and small A-
1, A-2, and A-3, each of which has a zero amplitude portion 9-4 on the bottom side, and a sipe bottom portion 9- which extends linearly in the depth direction from the portion 9-4. As shown in FIG. 3C, the sipe bottom portion 9-5 has a bulb portion 9 as shown in FIG.
By forming -6, it is desirable to alleviate the stress concentration at the sipe bottom and suppress the occurrence of cracks.

Further, as shown in FIG.
It is also possible to make trapezoidal portions -1, 9-2, and 9-3, and the opening amount of the sipe 9 (sipe width, wall surfaces 9-A, 9-
-B) is 0.3 to 1.0 mm, preferably 0.1 to 1.0 mm.
It is about 5 mm.

Further, as shown in FIG. 5, the sipe 9 opening on the tread surface of the projecting element 4 exemplified by the left and right shoulder blocks and the left and right center blocks may be in the horizontal direction, and is shown in FIG. The left and right center blocks may be horizontal sipes 9 and the left and right shoulder blocks may be diagonal sipes 9.

[0024]

According to the present invention described in detail above, since the sipe amplitude is reduced in the depth direction, the contact between the sipe walls decreases with the progress of wear, and the wall contact As a result, the increase in rigidity due to the progress of wear is offset, and good ice and snow performance can be maintained until the latter half of wear.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a part of a tire tread according to the present invention.

FIG. 2 is a sectional view of a projection element.

FIG. 3 shows three examples of a sipe form, (A) is a first example,
(B) is a sectional view of the second example, and (C) is a sectional view of the third example.

4A and 4B are cross-sectional views showing four examples of a sipe form, in which (A) shows a closed sipe, (B) shows an open sipe, (C) shows a semi-open sipe, and (D) shows a one-side open sipe.

FIG. 5 is a plan view showing an example of a horizontal sipe.

FIG. 6 is a plan view showing an example of a horizontal sipe and an oblique sipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tire tread 1A Tread surface 4 Projection element 9 Sipe A Amplitude

Claims (3)

[Claims] 1. A tire tread (1) comprising a projection element (4) forming a sipe (9) opening in a tread surface (1A), wherein the sipe (9) has a waveform in the depth direction. Alternatively, the tire tread is formed in a polygonal line shape, and the amplitude (A) of the waveform or the polygonal line becomes smaller as it reaches the depth direction. 2. The tire tread according to claim 1, wherein the amplitude (A) of the sipe (9) is composed of three types, large, medium, and small (A1) (A2) (A3). 3. The sipe (9) has a zero-amplitude portion (9-4) on the bottom side thereof, and extends from the portion (9-4) in the depth direction in a straight line form. The tire tread according to claim 1 or 2, wherein (5) is formed.