JP2001347811A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a center peripheral groove and left and right peripheral grooves and to improve draining performance by preventing block uneven wear in a tread of a pattern communicating the peripheral grooves by a lateral groove. SOLUTION: This tire is provided with the center peripheral groove 3 and left and right shoulder peripheral grooves 4L and 4R. Left and right center blocks 6L and 6R are formed by communicating the center peripheral groove 3 and the left and right shoulder peripheral grooves 4L and 4R by left and right lateral grooves 5L and 5R. The depth of each shoulder peripheral grooves 4L and 4R is formed shallower than that of the center peripheral groove 3.

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 tread having a center circumferential groove and left and right shoulder circumferential grooves in a zigzag shape, and a center circumferential groove and a shoulder circumferential groove. And a rib-lug pneumatic tire in which the lateral grooves are connected to each other.

[0002]

2. Description of the Related Art A pneumatic tire mounted on a heavy-duty vehicle such as a truck or a bus has a center circumferential groove formed on a tread of the tire and left and right shoulder circumferential grooves in a zigzag shape, thereby increasing the number of tires. The traction performance and the braking performance in the direction are improved, and the wet performance and the traction performance are improved by connecting the center circumferential groove and the left and right shoulder circumferential grooves by lateral grooves (Japanese Patent Laid-Open No. 11-34615). And JP-B-7-108606.

[0003]

The left and right lateral grooves connecting the center circumferential groove and the left and right shoulder circumferential grooves are biased by the left and right center blocks (so-called land portions) defined by these grooves. Since the abrasion easily occurs, the shallow groove has a shallow groove depth. However, when the depth of the lateral groove is set to be shallow, not only the problem that the drainage property (wet performance) is reduced occurs, but also the problem that the traction performance and the braking performance are reduced when the tread is worn and the lateral groove disappears. .

Therefore, the present invention relates to the center peripheral groove, the left and right shoulder peripheral grooves, and the lateral grooves connecting (connecting) these peripheral grooves, so as to have a relationship with each groove depth, thereby preventing uneven wear and improving wet performance. It is an object of the present invention to provide a pneumatic tire that is improved so as to be able to improve (maintain) traction performance and braking performance particularly during tread wear while improving.

[0005]

The present invention provides a tire tread 2 having a center circumferential groove 3 and left and right shoulder circumferential grooves 4L,
4R, and right and left lateral grooves 5L and 5R for connecting the center peripheral groove 3 to the left and right shoulder peripheral grooves 4L and 4R.
In the pneumatic tire 1 in which one or both of the 4Rs are formed in a zigzag shape, the following technical measures are taken to achieve the above object. That is, in the pneumatic tire according to claim 1, the groove depth b of the left and right shoulder circumferential grooves 4L and 4R is formed deeper than the groove depth a of the center circumferential groove 3, and the left and right lateral grooves are formed. 5L,
The groove depth c of 5R is formed shallower than the groove depth a of the center circumferential groove 3, and the groove bottoms of the left and right lateral grooves 5L, 5R have the groove depth c of the left and right shoulder circumferential grooves 4L, It has an inclined groove bottom 11 which is formed gradually deeper toward 4R.

[0006] With this configuration, the center peripheral groove 3 and the left and right shoulder peripheral grooves 4L, 4R and the lateral grooves 5L, 5R connecting the center peripheral groove 3 and the left and right shoulder peripheral grooves 4L, 4R are defined. Block (land) 6
L and 6R are the center peripheral grooves 3 where the groove depth c of the lateral grooves 5L and 5R is
Of the block 6
Uneven wear is prevented at the edges of the left and right grooves 6R, and the groove bottoms of the lateral grooves 5L, 5R are inclined grooves whose groove depth c is formed gradually deeper toward the left and right shoulder peripheral grooves 4L, 4R. The lateral groove having the inclined groove bottom 11 even when the tread 2 is worn while maintaining the wet performance, particularly the drainability from the center peripheral groove 3 to the left and right shoulder peripheral grooves 4L and 4R because the bottom 11 is provided. As long as 5L and 5R remain, traction performance and braking performance are maintained.

The depth of the groove bottom of the left and right lateral grooves 5L, 5R gradually increases (increases) over the entire length (groove longitudinal length) from one end (center peripheral groove side) to the other end (shoulder peripheral groove). The bottom of the left and right lateral grooves 5L and 5R may be a flat groove bottom 12 having a constant groove depth c and the left and right shoulder peripheral grooves 4L and 4R. Groove bottom 1 that gradually deepens toward
1 is recommended (claim 2).
Further, assuming that the separation length in the width direction of the tire tread 2 between the center peripheral groove 3 and the left and right shoulder peripheral grooves 4L and 4R is Z, the left and right lateral grooves 5 according to claim 2 are provided.
The length d between the flat groove bottom 12 and the inclined groove bottom 11 at the displacement position 13 in L and 5R is 1/1 / the distance from the center of the center circumferential groove 3.
It is recommended that it be set to be approximately equal to 2 · Z or outside 1/2 · Z (claim 3).

This is because if d <１ ／ · Z, the block rigidity of the left and right center blocks (land portions) may be non-uniform or low and uneven wear may occur. . Furthermore, the groove depth a of the center circumferential groove 3 according to claim 1 and the left and right shoulder circumferential grooves 4 according to claim 1.
The ratio a / b of L and 4R to the groove depth b is 0.85 to 0.9.
It is recommended to be set to 0 (claim 4). This is because if a / b> 0.90, the inclination angle of the inclined groove bottom 11 in the lateral grooves 5L, 5R becomes small, and the drainage toward the left and right shoulder peripheral grooves 4L, 4R becomes small, and conversely, If a / b <0.85, the rigidity balance between the center peripheral groove 3 and the left and right shoulder peripheral grooves 4L, 4R is deteriorated, and uneven wear is likely to occur at the edges of the left and right center blocks 6L, 6R. It becomes.

Further, the left and right lateral grooves 5L according to the second aspect,
5R, the ratio c / a to the groove depth a of the center circumferential groove 3 is 0.59 to 0.5.
63, while the groove depth c at the inclined groove bottom 11 is:
Ratio c / b of shoulder peripheral grooves 4L, 4R to groove depth b
Is set to 0.85 to 0.90 (claim 5). This is because c / a> 0.63 and c / b
If> 0.90, the depth of the lateral grooves 5L, 5R becomes too large, the rigidity of the left and right center blocks 6L, 6R is reduced, causing uneven wear, and c / a <0.59 and c / a.
If /b<0.85, the lateral grooves 5L, 5R become too shallow, and the lateral grooves 5L, 5R disappear while the tread 2 is worn, which is disadvantageous in terms of traction performance and braking performance (point).

Further, the present invention provides the tire tread 2 with a center circumferential groove 3 and left and right shoulder circumferential grooves 4L, 4R, and the center circumferential groove 3 and the left and right shoulder circumferential grooves 4L, 4L,
In the pneumatic tire 1 having the left and right lateral grooves 5L and 5R communicating with the 4R, the following technical measures are taken in order to achieve the above object. That is, claim 6
The center circumferential groove 3 of the pneumatic tire according to (1) is characterized in that it has a zigzag shape in which the deflection angle θ is 85 ° to 105 °.

When θ> 105 °, the traction performance and braking performance in the vertical direction (circumferential direction) decrease, and when θ <85 °, the center block 6
This is because the corners (edges) of L and 6R become acute angles and cause chipping. Further, in the above-described claims 1 to 6, a projection 1 for preventing stone biting is provided on the groove bottom of the center circumferential groove 3.
It is recommended that 4 is raised (claim 7).

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure and operation (function) of an embodiment of a pneumatic tire 1 according to the present invention will be described below with reference to the drawings. 1 (1) and 1 (2) show a pneumatic tire 1, more specifically a radial tire 1 mounted on a heavy-duty vehicle such as a truck or a bus, and a tire tread (ground contact surface) 2 on the tire equator. The center peripheral groove 3 and left and right shoulder peripheral grooves (also referred to as side peripheral grooves) 4L and 4R which are located with a separation length Z in the tread width direction on the left and right sides, and the center peripheral groove 3 and the left and right shoulder peripheral grooves are provided. The grooves 4L and 4R are connected (connected) by left and right lateral grooves 5L and 5R to define left and right center blocks 6L and 6R, and have left and right shoulder ribs 7L and 7R. Rib 7
Lug grooves 8L and 8R are formed in L and 7R.

In FIG. 1B, reference numeral 9 denotes a radial carcass, and reference numeral 10 denotes a breaker or a belt. In the first embodiment shown in FIG. 1A, both the center circumferential groove 3 and the left and right shoulder circumferential grooves 4L and 4R extend in the circumferential direction in a zigzag shape. The right and left deflection angles θ are 85 ° to 105 ° at the connection portions with the lateral grooves 5L and 5R, and the shape is a zigzag shape of a snapper, and the left and right shoulder circumferential grooves 4L and 4R.
Are connected to the left and right lateral grooves 5L and 5R,
L-1, 4R-1, and has a triangular waveform zigzag shape having one outer bent portion 4L-2, 4R-2 between the inner bent portions. 4R is shifted in phase in the circumferential direction.

Here, the reason why the left and right deflection angles θ in the center circumferential groove 3 are 85 ° to 105 ° is that when θ> 105 °, the vertical direction (the circumferential direction, ie, the tire rotation direction) and the center circumferential groove 3 This is because the traction performance and the braking performance are deteriorated due to the rising (parallel), and when θ <85 °, the deflection angle becomes too acute and the corners 6L-1, 6R-1 of the center blocks 6L, 6R. This is because the chipping phenomenon may occur in The depth of the center circumferential groove 3 is a, the left and right shoulder circumferential grooves 4L,
The groove depth of 4R is b and the groove depth of left and right lateral grooves 5L and 5R is c.
As shown in FIG. 2, the groove depth b of the left and right shoulder circumferential grooves 4L, 4R is formed deeper than the groove depth a of the center circumferential groove 3, and the left and right lateral grooves 5L,
The groove depth c of 5R is formed shallower than the groove depth a of the center peripheral groove 3, and the groove bottom of the left and right lateral grooves 5L, 5R has the groove depth c of the left and right shoulder peripheral grooves 4L, 4R. Has an inclined groove bottom 11 that is formed gradually deeper.

With such a configuration, a block (land portion) defined by the lateral grooves 5L and 5R connecting the center peripheral groove 3 and the left and right shoulder peripheral grooves 4L and 4R.
6L, 6R, the groove depth c of the lateral grooves 5L, 5R is made shallower than the groove depth a of the center circumferential groove 3, so that uneven wear at the edges of the blocks 6L, 6R is prevented, and the lateral grooves Since the groove bottoms 5L and 5R have the inclined groove bottoms 11 whose groove depth c is formed gradually deeper toward the left and right shoulder peripheral grooves 4L and 4R, the wet performance, especially the center peripheral groove 3 The traction performance and the braking performance are maintained as long as the lateral grooves 5L, 5R having the inclined groove bottoms 11 remain even if the tread 2 is worn, while improving drainage performance with respect to the left and right shoulder circumferential grooves 4L, 4R. It is.

Referring to FIG. 2 more specifically,
The groove bottoms of the left and right lateral grooves 5L, 5R have a flat groove bottom 12 having a constant groove depth c and an inclined groove bottom 11 in which the groove depth c gradually increases toward the left and right shoulder circumferential grooves 5L, 5R. And when the separation length in the width direction of the tire tread 2 between the center peripheral groove 3 and the left and right shoulder peripheral grooves 5L, 5R is Z, the left and right lateral grooves 5L, 5R
Displacement position 13 between flat groove bottom 12 and inclined groove bottom 11
Distance (length) d is 1/2 of the center circumferential groove center.
Set to be approximately equal to Z or outside 1 / 2Z.

The groove bottoms of the left and right lateral grooves 5L and 5R gradually extend from one end (center peripheral groove side) to the other end (shoulder peripheral groove) (full length in the groove longitudinal direction) as shown by phantom lines in FIG. It is also possible to form the inclined groove bottom 11 having a larger (deeper) depth. However, as described above, d ≒
By setting the flat groove bottom 12 up to the displacement position 13 and setting the inclined groove bottom 11 thereafter to 1 / 2.Z, drainage is improved while preventing uneven wear of the left and right center blocks 6L and 6R. . Further, the ratio a / b of the groove depth a of the center circumferential groove 3 to the groove depth b of the left and right shoulder circumferential grooves 4L, 4R is set to 0.85 to 0.90.

This is because if a / b> 0.90, the inclination angle of the inclined groove bottom 11 in the lateral grooves 5L, 5R becomes small, and the drainage toward the left and right shoulder peripheral grooves 4L, 4R becomes small. Conversely, if a / b <0.85, the rigidity balance between the center peripheral groove 3 and the left and right shoulder peripheral grooves 4L, 4R becomes poor, and the left and right center blocks 6L, 6R.
In this case, uneven wear at the edge portion tends to occur. Regarding the groove depth c at the flat groove bottom 12 in the left and right lateral grooves 5L and 5R, the ratio c / a to the groove depth a of the center circumferential groove 3 is 0.59 to 0.63, while The ratio c / b of the groove depth c to the groove depth b of the shoulder peripheral grooves 4L and 4R is set to 0.85 to 0.90.

This is because c / a> 0.63 and c / b>
If it is 0.90, the depth of the lateral grooves 5L, 5R becomes too large, and the rigidity of the left and right center blocks 6L, 6R decreases, causing uneven wear, and c / a <0.59 and c / a.
If b <0.85, the lateral grooves 5L, 5R become too shallow, and the lateral grooves 5L, 5R disappear during the wear of the tread 2,
This is because it is disadvantageous in terms of traction performance and braking performance (point). The displacement position of the inclined groove bottom 11 may be a plurality of positions (two positions 13 and 13A in FIG. 3) in the longitudinal direction of the groove as shown in FIG.
As shown in the figure, an arc-shaped inclined groove bottom 11 may be used.

FIGS. 5 to 7 show other useful embodiments of the present invention. In the second embodiment shown in FIG.
Like the embodiment, it is formed in a zigzag shape, but the left and right shoulder circumferential grooves 4L, 4R are formed straight in the circumferential direction. In the third embodiment shown in FIG. 6, the left and right shoulder peripheral grooves 4L and 4R have a zigzag shape, but the center peripheral groove 3 is formed straight in the circumferential direction. Furthermore, FIG. 7 (1) (2)
In the fourth embodiment shown in FIG. 5, a projection 14 for preventing stone biting is formed on the center peripheral groove 3 from the bottom of the groove, and the height of the protrusion is between the flat groove bottom 12 of the lateral grooves 5L and 5R. At step 14
A.

In addition, in FIGS. 5 to 7, the configurations shown in FIGS. 1 to 4 can be similarly adopted except for the configuration described above, and common parts use common reference numerals. Although the embodiment of the present invention is as described above, various design changes are possible. For example, the zigzag center peripheral groove 3 and the left and right shoulder peripheral grooves 4L, 4R may have bent portions in a meandering shape having an arcuate waveform. 7 can be formed in the left and right shoulder circumferential grooves 4L and 4R, and the protrusions 14 can be continuous or intermittent as shown in the circumferential direction. There may be.

Further, when the center circumferential groove 3 is straight as shown in FIG. 6, the width of the groove is slightly widened, and the left and right center blocks 6L, 6L are positioned at the center (on the tire equator).
A thin rib having the same height as R may be formed to protrude to improve the straightness. Also, left and right lug grooves 8L, 8
As for R, this is connected to the left and right shoulder circumferential grooves 4L, 4R.
The traction and braking performance at the time of cornering can be improved, and the lateral drainage at the shoulder portion can be improved.

[0023]

As described in detail above, according to the present invention, traction performance and braking performance can be maintained while improving wet performance while preventing uneven wear of the tread.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention, wherein (1) is a plan view and (2) is a cross-sectional view.

FIG. 2 is an enlarged sectional view taken along the line AA of FIG. 1 (1).

FIG. 3 is a sectional view showing another example of FIG. 2;

FIG. 4 is a sectional view showing another example of FIG. 2;

FIG. 5 is a plan view showing a second embodiment of the present invention.

FIG. 6 is a plan view showing a third embodiment of the present invention.

FIG. 7 shows a fourth embodiment of the present invention, wherein (1) is a plan view and (2) is a cross-sectional view.

[Explanation of symbols]

 Reference Signs List 1 tire 2 tread 3 center circumferential groove 4L, 4R shoulder circumferential groove 5L, 5R lateral groove 6L, 6R center block

Claims (7)

[Claims] 1. A tire tread (2) includes a center peripheral groove (3) and left and right shoulder peripheral grooves (4L) (4R), and the center peripheral groove (3) and the left and right shoulder peripheral grooves (4L). (4R) and left and right lateral grooves (5L) (5
R), and one or both of the center circumferential groove (3) and the left and right shoulder circumferential grooves (4L) and (4R) are formed in a zigzag shape. The groove depth (b) of the left and right shoulder peripheral grooves (4L) and (4R) is formed deeper than the groove depth (a) of (3), and the left and right lateral grooves (5L) and (5R) are formed.
The groove depth (c) of the left and right lateral grooves (5) is formed shallower than the groove depth (a) of the center circumferential groove (3).
L) The groove bottom of (5R) has an inclined groove bottom (11) in which the groove depth (c) is gradually deepened toward the left and right shoulder circumferential grooves (4L) and (4R). A pneumatic tire characterized by the following. 2. The bottom of the left and right lateral grooves (5L) and (5R) has a flat groove bottom (12) having a constant groove depth (c), and the groove depth (c) has a left and right shoulder circumference. Groove (4L) (4
The pneumatic tire according to claim 1, characterized in that the pneumatic tire is constituted by an inclined groove bottom (11) gradually deepening toward R). 3. The width of the tire tread (2) between the center peripheral groove (3) and the left and right shoulder peripheral grooves (4L) (4R) in the width direction is (Z). The displacement position (1) between the flat groove bottom (12) and the inclined groove bottom (11) in the left and right lateral grooves (5L) (5R) according to claim 2.
The pneumatic tire, wherein the length (d) up to 3) is set to be substantially equal to or less than 1 / 2.Z from the center of the center circumferential groove (3). 4. The groove depth (a) of the center circumferential groove (3) according to claim 1, and the groove depth (b) of the left and right shoulder circumferential grooves (4L) (4R) according to claim 1. The ratio a / b is
A pneumatic tire characterized by being set to 0.85 to 0.90. 5. The left and right lateral grooves (5L) according to claim 2.
In the groove depth (c) at the flat groove bottom (12) in (5R), the ratio c / a to the groove depth (a) of the center circumferential groove (3) is 0.59 to 0.63, The groove depth (c) at the inclined groove bottom (11) is determined by the shoulder circumferential groove (4).
L) The ratio c / b of the (4R) to the groove depth (b) is 0.8.
A pneumatic tire characterized by being 5 to 0.90. 6. The tire tread (2) includes a center peripheral groove (3) and left and right shoulder peripheral grooves (4L) (4R), and the center peripheral groove (3) and the left and right shoulder peripheral grooves (4L). (4R) and left and right lateral grooves (5L) (5
R), the center circumferential groove (3) has a deflection angle (θ) of 85 ° to 1 °.
A pneumatic tire having a zigzag shape set at 05 °. 7. The pneumatic tire according to claim 1, wherein a protrusion (14) for preventing stone biting is protruded at a groove bottom of the center circumferential groove (3). .