JPS62175205A - Tread pattern for pneumatic tire - Google Patents

Abstract

PURPOSE:To make rigidity in a block uniform as well as to make improvements in wettability and wear resisting capacity, by specifying depth and width of each subgroove, in case of such one that formed each block in a way of setting up plural straight grooves and subgrooves on a tire tread, respectively. CONSTITUTION:On a tire tread, there are provided with plural straight grooves 1-4 as annular form in the tire circumferential direction E-E', and from each of the these straight grooves 1-4, there are provided with plural subgrooves 5 and 6 in the tire radial direction, whereby each block m is formed there. In the abovementioned tread pattern, depth of each of these subgrooves 5 and 6 adjacent to the block m is made shallower than that of the central part at both ends A1-A2 and C1-C2 in the tire radial direction of these subgrooves 5 and 6. In addition, tire radial width in the shallowest portion at both these ends A1-A2 and C1-C2 of these subgrooves 5 and 6 is set to be within the the range of below 20% of the tire radial direction of each block m.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in a tread pattern, and more particularly to a tread pattern for a pneumatic tire that can improve wet performance and wear resistance performance.

[Prior art]

Conventionally, tires have tended to become flatter in order to fully demonstrate their performance on vehicles that are increasing in speed. In order to prevent the deterioration of wet performance due to the expansion of the tire contact width due to flattening, the tread pattern formed on the tire tread is mainly a block pattern having straight grooves in the tire circumferential direction. An example of this is shown in FIG.

FIG. 10 is an explanatory diagram showing an example of a tread pattern of a conventional pneumatic tire. In FIG. 10, there are a plurality of straight grooves 1 on the tire tread in the tire circumferential direction EE',
2, 3.4 are provided in an annular shape. Furthermore, a plurality of sub-grooves are arranged extending from these straight grooves in the tire radial direction (tire width direction) (in FIG. 10, sub-grooves 5.6 are shown as a representative). As a result, block m is formed. In addition, in FIG. 10, T is the tire ground contact width. Next, Fig. 11 shows the main part of Fig. 10, and Fig. 12 (A) and (B).

(C) shows A, A, and 2 lines in Fig. 11, respectively.
The cross section of BI B2 line and CI C2 line is shown. 12th
In figures (A), (B), and (C), a, b.

C is the groove depth of the cross section of sub groove 5 or 6, respectively, α1・
α2・β1. β2, γ1. γ2 does not represent the groove wall angle of the cross section of the sub-groove 5 or 6, respectively, with respect to the tire normal direction.

The groove wall angles are each exactly the same. Moreover, the sub-groove depths are the same or shallower than the straight grooves, but they are the same.

However, the blocks m, which are partitioned and separated by straight grooves and sub-grooves, are weak in rigidity, and uneven wear occurs particularly at locations where the angle of the grooves creates an acute corner, which is disadvantageous for wet performance. Therefore, as shown in No. 10 and FIG. 11, the acute corner end n of the block m was removed to solve this problem. However, although the tire with the sharp edge n removed in this manner is advantageous in eliminating uneven wear, it has the disadvantage that grip performance on low μ (mu) road surfaces such as Uso 1 is reduced.

[Purpose of the invention]

The present invention was made in order to equalize the rigidity of blocks in a 1-let pattern, and an object of the present invention is to provide a 1-let pattern of a pneumatic tire that can achieve both wet performance and wear resistance performance. do.

[Structure of the invention]

For this reason, the present invention provides a tire tread with a plurality of straight grooves arranged in an annular manner in the tire circumferential direction, and a plurality of sub-grooves arranged in the tire radial direction from these slate grooves to form air blocks. In the 1 to 1 red patterns of the tire, (1) the depth of the sub-groove adjacent to the block is shallower at both ends of the sub-groove in the tire radial direction than at the center, and (2) the depth of the sub-groove adjacent to the block is shallower at both ends of the sub-groove in the tire radial direction; The gist of the present invention is a tread pattern for a pneumatic tire, characterized in that the tire radial width at its shallowest point is within 20% of the tire radial width of each of the blocks.

Hereinafter, the configuration of the present invention will be explained in detail with reference to the drawings. In addition, FIG. 1O to FIG. 12(A).

Similar parts as in (B) and (C) are represented by the same numbers and symbols.

FIG. 1 is an explanatory diagram showing an example of a tread pattern of a pneumatic tire of the present invention. FIG. 2 is an explanatory diagram showing the main part of FIG. 1, and FIG. 3 (A).

(B) and (C) are A1A2 in Fig. 2, respectively.
FIG.

In FIG. 1, as in FIG. 10, there are a plurality of straight grooves 1, 2, 3 on the tire tread in the tire circumferential direction EE'.
．． 4 are provided in an annular shape, and a plurality of sub-grooves are arranged in the tire radial direction from these straight grooves. In the present invention, in order to equalize the rigidity of the blocks in the tread pattern shown in FIG. 1, the following (1) and (
2) was stipulated. In this case, when the tire tread is wet, it is necessary to have the ability to separate and drain the water film that forms between the ground and the tread using grooves, and for this reason, if the rigidity of the block is uneven, the tire tread will not contact the ground on the block surface. This is because the pressure becomes uneven and the ability to drain water from the groove is reduced.

(1) Determine the depth of the sub-groove 5.6 adjacent to the block m at both ends of the sub-groove 5.6 in the tire radial direction (AIA2, C
IC2) was made shallower than the central part (B1. B2).

That is, in FIGS. 3(A), (B), and (C), a
, cab. It is preferable to make the depth 1 mm or more shallow.

In addition, both ends of the sub-groove 5.6 in the tire radial direction (AHA2,
In CI C2), it is preferable that the groove wall angle of the acute angle part of block m with respect to the tire normal direction is 5 degrees or more larger than the groove wall angle of the obtuse angle part of block m with respect to the tire normal direction.

That is, in FIGS. 3(A), (B), and (C), α2>α1 and γ1>γ2.

(2) Both ends of sub-grooves 5 and 6 (AI A2, CI-
The tire radial width of the shallowest portion in C2) is within 20% of the tire radial width of each block m.

This is to strengthen the edge of block m.

Next, main parts of another example of the tread pattern of the present invention are shown in FIGS. 4 and 5.

FIG. 4 shows a tread pattern in which the sub-grooves 5.6 are bent into a chevron shape. α2>α1, B2>β1, T1>T2,
FIG. 5, where a-C<b, shows a trend pattern in which the sub-grooves 5.6 are bent into a waveform. α2〉α5, B2-
β+, Tt>72, a=c<b.

EXAMPLES The effects of the present invention will be specifically explained below with reference to Examples.

Examples Various tests were conducted using the following tires of the present invention and conventional tires. The results are shown below.

(a) Tire of the present invention.

Smooth tires with tire size 205/60 R15.

It has the trend pattern shown in Figure 1. α1−5 °
, α2-15°, β1-B2-10°, γ-electro-15°
, T2−5°. a = 6.5mm, b =
8.0mm.

c = 6.5mm, straight groove depth 8.0mm
The tire radial width of the 6.5 mm 0 sub-groove depth is 15% of the tire radial width of the block.

fb) Conventional tires.

Smooth tires with tire size 205/60 R15.

It has a tread pattern shown in FIG. α1-α2
-β1-B2 =r+ =r2=10', a-b =
c = 7.0mm, straight groove depth 8.0mm
.

Ontsuki Road Gate Wiping Test: The test was conducted on the same car model and under the same conditions. The results are expressed as an index in FIG. The larger the index, the better. From Figure 6,
It can be seen that the tire of the present invention is superior.

Quasi-slip test and pressure comparison: The friction coefficients on dry and wet road surfaces were compared.

Based on this result, the friction coefficient of the conventional tire on dry road surface is 10
0 and expressed as an index in FIG. The larger the index, the better. From FIG. 7, it can be seen that the tire of the present invention is particularly excellent on wet road surfaces.

Cornering: Rim 6JJ x 15, internal pressure 2.0kg/cA, load 4
The measurement was carried out under the condition of 00 kg. The results are shown in FIG.

From FIG. 8, it can be seen that the tire of the present invention is significantly superior to the conventional tire especially at slip angles of 4° or more.

” A single and unique experience: The tires of the present invention and the conventional tires were installed on a domestically produced 2-liter passenger car, and the tires were driven for 110,000 km under the same conditions.
The amount of wear on the parts that were also worn was measured. The results are expressed as an index in FIG. The smaller the index, the better. From FIG. 9, it can be seen that the tire of the present invention wears uniformly, so the index value is small and the amount of wear is small.

〔Effect of the invention〕

As explained above, according to the present invention, since the sub-grooves are defined to equalize the rigidity of the blocks, it is possible to improve the wet performance, wear resistance performance, cornering performance, etc. of the pneumatic tire. In addition, in the present invention, unlike the conventional tread pattern shown in FIG. 10, the sharp corner edge n is not removed (it is also possible to avoid deterioration of grip performance on a low μ (mu) IiS surface such as when wet). do not have.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of a trend pattern of the pneumatic tire of the present invention, FIG. 2 is an explanatory diagram showing the main part of FIG. 1, and FIGS. 3 (A) and (B). (C) are AI A2 line and BI line in Figure 2, respectively.
It is a sectional view of line B2 and line CI C2. FIGS. 4 and 5 are explanatory diagrams showing the main parts of the other side of the tread pattern of the pneumatic tire of the present invention, respectively. Figure 6 is an explanatory diagram that graphically shows the circular turning speed of tires on wet roads, Figure 7 is an explanatory diagram that graphically depicts the coefficient of friction of tires on dry and wet roads, and Figure 8 is the cornering force and slip of tires. FIG. 9 is an explanatory diagram showing the wear resistance performance of the tire in a graph. Fig. 10 is an explanatory diagram showing an example of the torso pattern of a conventional pneumatic tire, Fig. 11 is an explanatory diagram showing the main part of Fig. 10, and Figs. 12 (A), (B), and (C) are They are sectional views taken along the A+ A2 line, the BI B2 line, and the C+-C2 line in FIG. 11, respectively. ], 2, 3.4... ・Straight groove, 5.6...
Sub-groove, m...block.

Claims (1)

[Claims] In a tread pattern of a pneumatic tire in which a block is formed by providing a plurality of straight grooves annularly in the tire tread surface in the tire circumferential direction and a plurality of sub-grooves arranged from these straight grooves in the tire radial direction, (1) the block; (2) the depth of the sub-groove adjacent to the block is shallower at both ends of the sub-groove in the tire radial direction than at the center; A tread pattern of a pneumatic tire characterized by having a tread pattern within 20% of the tire's radial width.