JPH02179509A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To reduce the deflected abrasion of a block without reducing ice performance by disposing a plurality of thin notches crossing to the tire circumferential direction on a block pattern and setting the depth of each notch in such a manner as to gradually increase the depth from the tread-in side toward the kickout side. CONSTITUTION:A tire has a determined pattern set by blocks 3 formed of circumferential main grooves 1 and sub-grooves 2 in the direction crossing thereto. In this case, a plurality of thin notches 41-43 are formed on each block 3 with the respective depth d1-d3 being varied. The respective depth d1-d3 is set in such a manner as to gradually increase from the tread-in side R toward the kick-out side F. Namely, the rigidity of the block 3 is set to be larger on the tread-in side R than on the kick-out side F. Hence, the tread-in side R of the block 3 is prevented from floating from the tread at the time of braking. Thus, the difference in abrasion amount between mutual small blocks partitioned by each notch 41-43 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pneumatic tire that has improved wear resistance without impairing its performance on icy and snowy roads as a studless tire.

[Conventional technology]

Conventional pneumatic tires with a block-based tread pattern, which consists of a large number of blocks on the tread surface divided by a main groove in the tire circumferential direction and a minor groove in a direction transverse to the main groove, are effective for braking and driving on icy and snowy roads. To improve performance, each block has a number of thin cuts that cross the circumference of the tire.

As shown in FIG. 5, these thin cuts 4 usually have the same depth d.

In such a pneumatic tire in which the depth d of the plurality of thin cuts 4 is the same, when braking force is applied while driving, the block 3
falls down, and the small block 5 on the stepping side R lifts up from the road surface the most, and this small block 5 is the only small block 5 that is not worn compared to the other small blocks 5, which tends to cause uneven wear. Therefore, as shown in Fig. 6. As shown, the difference in the amount of wear between the small blocks 5 in the block 3 becomes significant,
As shown in FIG. 7, the wear amount difference Δa between the blocks 4
There was also a problem that

Such uneven wear within the blocks and between the blocks deteriorates the ground contact performance of the blocks 3 and causes the block 3 to lose its edge effect, so there is a problem that the tire's performance on ice and snow roads deteriorates over time. Ta. Furthermore, such uneven wear is particularly noticeable in tires with high ground contact pressure, such as tires for heavy loads such as trucks and buses.

[Problem to be solved by the invention]

The purpose of the present invention is to prevent uneven wear of the blocks having the thin notches mentioned above, without deteriorating the ice and snow road performance of pneumatic tires with block patterns on the tread surface, and to improve the wear resistance of pneumatic tires. Our goal is to provide tires that fit.

[Means to solve the problem]

An object of the present invention is to provide a pneumatic tire having a block pattern on the trend surface, in which each block is provided with at least two thin cuts that intersect with the circumferential direction of the tire, and within these thin cuts, it is possible to This can be achieved by making the depth of the thin cut located closest to the side edge the shallowest (the thin cut located closer to the kick-up side is made deeper in sequence).

Hereinafter, the present invention will be specifically explained based on the drawings.

FIG. 2 is a plan view showing an example of the block pattern of the tire of the present invention, and as shown in the figure, the tire circumferential direction E-E
A pattern is formed by a block 3 formed by a main groove 1 and a sub-groove 2 extending across the main groove 1.

As shown in FIG. 1, which is a cross section taken along the line A-A' in FIG. 2, at least two thin incisions 41.
4! , h are not the same but different in their depths d+, di, and ds.

The features of the present invention are that among these plurality of thin cuts, the thin cut 4I located closest to the R end on the stepping side of the block 3 has the shallowest depth d, and that The depth of the thin cut 4 located on the kicking side F is gradually deeper than R, that is, the thin cut 4 m is provided in the same block 3 from the stepping side R to the kicking side F of the block 3.
The depth dX of 48 is deeper than the depth dl of 4.48, and the depth dX of 48 is deeper than the depth d2 of 42. The depth d of the thin cut 43 on the side closest to the kick-up side F end is made the deepest.

As a result, in the tire of the present invention, the rigidity within the same block 3 is greater on the stepping side R than on the kicking side F, so that lifting of the block from the road surface on the stepping side during braking is suppressed. Therefore, as shown in FIG. 3, it is possible not only to reduce the difference in the amount of wear between the small blocks 51+, 5z, 5s, and 5m divided by the thin cuts 4+, 4z, and As, but also to
As shown in the figure, the wear amount difference Δa between the blocks 3 can also be reduced.

It is desirable that the thin notch formed in the block of the present invention, which intersects with the tire circumferential direction, be formed so that both ends thereof communicate with the main body forming the block, but only at least one end of this notch communicates with the main body. It is also possible to just do so. The direction of this thin cut is preferably perpendicular to the tire circumferential direction, but it may also be slightly inclined within a range that does not impede braking performance or drivability, preferably with respect to the tire circumferential direction. It is best to set the angle to 30@ or less.

Further, the shape of the thin cut can also be a straight line, a curved line, a broken line, or the like.

In order to exhibit the excellent braking performance of the tire of the present invention, it is preferable to use the tire by attaching it to an axle such as a steered wheel or an idler wheel of a vehicle, where only braking force is applied. Furthermore, by forming the thin incisions of the present invention, for example, the thin incisions 4 shown in FIG. 9, in a tire having a directional pattern in which the rotational direction of the tire is designated, for example, a block of the tread pattern shown in FIG. , the uneven wear resistance of a tire having the above-mentioned directional block pattern can be significantly improved.

The present invention will be specifically explained below by comparing examples with conventional examples.

Incidentally, uneven wear resistance, braking performance on snow/ice, and climbing performance on snow were evaluated by the following methods.

■Dish! Performance: Test tires were installed on all wheels of a large vehicle (2/D), and the braking and
After driving 15,000 kilometers on a frequently driven course, the heel-and-toe difference in the block was measured and expressed as an index.

The larger this index is, the better the uneven wear resistance is.

Above and above: A large vehicle (2/D) with test tires installed on all wheels, braked from 40 km/h on a snow-packed or icy road, measured the braking distance, and expressed it as an index. . The larger this index is, the better the braking performance is.

1st place! Test tires were attached to the drive wheels of a large-sized vehicle (2/D) the next day, and the time required to climb up a 200-meter section at an initial speed of 30 km/hour on a slope of a compressed snow road was measured and expressed as an index. . The larger this index is, the better the pitching (driving) performance is.

Embodiment, Conventional Example It has the block pattern shown in Fig. 2, and the leading depth is 1.
4.5+++a+, the depth of the minor groove is 10.0m11+, the thin cut shown in Figure 14. The depth dl is 9.0 mm,
The depth d3 of 4s is 6.5n+m, 4! depth d2
was 7.5 mm and the tire size was 650 R16, and a conventional tire that was the same as the above-mentioned inventive tire except that the depth d of the thin cuts 4 shown in Fig. 5 was all 7.5 mm. These tires were evaluated for uneven wear resistance, braking performance on ice, braking performance on snow, and climbing performance on snow. The results are shown in the table.

The evaluation results are expressed as index values based on the value of the conventional tire (100).

(Margins below this page) From the table, it can be seen that the tire of the present invention maintains the same snow braking performance and snow climbing braking performance as conventional tires, and has significantly improved uneven wear resistance compared to conventional tires. It can be seen that it also has excellent braking performance on ice.

〔Effect of the invention〕

According to the present invention, at least two thin cuts are provided in the blocks constituting the block pattern of the tread surface, and the thin cuts are located closest to the stepping side end of the block when the tire rotates. By setting the depth to the shallowest and gradually increasing the depth from the stepping side to the kicking side, and increasing the rigidity of the stepping side within the same block, the In addition, it is possible to reduce uneven wear between the blocks and improve the wear resistance of the tire.

[Brief explanation of the drawing]

1 is a sectional view taken along the line AA' in FIG. 2 showing an example of the cross-sectional shape of the block of the tire of the present invention; FIG. 2 is a plan view showing an example of the block pattern of the present invention; Figures 3 and 4 are cross-sectional views showing the wear conditions within the same block and between blocks of the tire of the present invention, Figure 5 is a cross-sectional view of blocks of a conventional tire, and Figures 6 and 7 are respectively , a cross-sectional view showing wear conditions within the same block and between blocks of a conventional tire, FIG. 8 is a plan view showing an example of a block pattern with directionality, and FIG.
It is a sectional view of the block of the figure in the tire circumferential direction. 1... Main groove, 2... Minor groove, 3... Block, 4...
...Thin cut, F...Kicking side, R...Stepping side. Figure Figure 3 Figure Figure 6 Figure 7 @Figure 2 Figure 8 Figure

Claims (1)

[Claims] In a pneumatic tire with a block pattern, each block is provided with at least two thin cuts that intersect with the circumferential direction of the tire, and among these thin cuts, the thin cut located closest to the stepping side end of the block is A pneumatic tire characterized by having the shallowest depth, and the thinner notches located on the kick-up side gradually become deeper.