JPS63137003A - Tire for snowy or icy road - Google Patents

Abstract

PURPOSE:To make it possible to exercise the performance of a tire up to the final condition of abrasion, by specifying the rubber which composes a tread, forming block by main grooves and auxiliary grooves, and providing lateral calves with specific depths at the block linking to the main grooves. CONSTITUTION:A tread is formed on a rubber with the 100% modulus at -20 deg.C less than 32kg/cm<2>, and center blocks 4..., and shoulder side blocks 3... are formed by main grooves 1 and auxiliary grooves 2. At each block 3 or 4, numerous lateral calves 5 are provided linking to the main grooves 1. In this case, the depths of grooves of the calves in the area (l1) 1 to 10mm from the end where the calf 5 is linked to the main groove 1 is set 60% or more of he depth of the main groove 1, and that in the remaining area (l2) is set less than 50% of the depth of the main groove 1. In such a composition, the snowy condition property and the dry property can be maintained until the tire is at the final abrasive condition.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to tires for driving on snowy and icy roads.

[Prior art]

Generally, tires for snowy and icy roads use 120% tread rubber.
A rubber with a low modulus of 100% at °C is used,
The tread pattern employs a block-based pattern, and the block surface is provided with a curve in the cross-sectional direction. This tread configuration improves traction on snowy and icy roads (hereinafter referred to as snow performance).

In order to improve the above-mentioned snow performance, it is better to connect the curve to the main groove, but if this is done, the block rigidity will be extremely low, and the maneuverability such as steering stability on dry road surfaces (hereinafter referred to as , dry performance) may deteriorate,
This causes uneven wear in the tire circumferential direction.

Conventionally, such countermeasures have generally been taken by reducing the depth of the entire curve to increase the rigidity of the entire block, or by making the end of the curve connected to the main groove shallower. However, with these measures, when the depth of the curve becomes small at the end of block wear,
The problem was that the functions based on curves could no longer be fully demonstrated, resulting in a significant drop in snow performance.

[Purpose of the Invention] The purpose of the present invention is to solve the above-mentioned conventional problems and to effectively maintain the excellent snow performance and dry performance achieved by the curved block pattern until the final stage of block wear. Our objective is to provide tires for snowy and icy roads.

[Structure of the invention]

The tire of the present invention that achieves the above object has a tread portion made of rubber having a 100% modulus of 32 kg/cJ or less at -20°C, and a plurality of main grooves extending in the circumferential direction of the tire on the tread surface, and a plurality of main grooves extending in the circumferential direction of the tire. A block basic pattern is formed from a minor groove that crosses the main groove, and each block is provided with a curve that crosses the circumferential direction of the tire and has at least one end communicating with the main groove, and the length of the curve is 1 to 1 from the communicating end of the curve to the main groove. The depth in the range of 1 mm is 6 of the groove depth of the main groove.
0% or more, and the average depth of the other portions is 50% or less of the groove depth of the main groove.

Figures 1 and 2 show trends in tires for snowy roads according to embodiments of the present invention. -.-91 is a plurality of main grooves extending in the circumferential direction of the tire; 2. -.-12 is a sub-groove extending across the circumferential direction of the tire.

The sub-groove 2 communicates between the main grooves 1 and 1 adjacent to each other, and between the outermost main groove 1 and a part of the shoulder outside,
As a result, a large number of center-side blocks 4, . . . , 4 and shoulder-side blocks 3. −・.

3.

Each block 3, 4 is provided with at least one, preferably a large number of curves 5 cut into each block so as to communicate with the main groove 1. This curve 5 has end regions 3s and 4s of length 11 communicating with the main groove 1, as will be described in detail later.
It is formed to be deep in this region, and shallow in other regions 3c and 4c having a length of 12 excluding this region.

In the tire of the present invention, in the above-described configuration, the tread rubber has a 100% modulus of 3 at -20°C.
It is necessary to use one with a weight of 2 kg/ad or less. This 100% modulus at -20℃ is 32kg/
If the rubber is larger than cJ, it will not be possible to exhibit the desired snow performance that is the objective of the present invention.

In addition, in order to exhibit snow performance, the tread pattern formed on the tread surface needs to be a block-based pattern as illustrated in FIG. 2, and the block preferably has at least one curve. It is necessary to provide a large number of

In the present invention, the curve provided on the block must have at least one end communicating with the main groove. It is preferable that the curve communicates with the main groove by making both ends communicate with each other as in the embodiment shown in FIGS.
Like the center block 4 of the embodiment shown in the figure, only one end may be communicated.

Moreover, since the curve only needs to cross the tire circumferential direction, it does not necessarily have to be perpendicular to the tire circumferential direction as illustrated in FIG. 2, and may be a curve that intersects at a somewhat oblique angle.

This curve allows the block rigidity to be adjusted depending on its depth, and its flexibility improves traction on snowy and icy roads. In the present invention, the depth of the curve that performs such a stiffness adjustment effect is deepened at the end communicating with the main groove to improve snow performance, and by making it shallower in other areas other than this, the depth of the curve as a whole is improved. This maintains rigidity, prevents deterioration of dry performance, and prevents step wear in the tire circumferential direction.

Furthermore, the present invention is characterized in that, unlike conventional tires, the force depth is made shallow at the end communicating with the main groove;
Compared to a block that is deeper in the middle, the rigidity of the block as a whole is the same, and the dry performance is the same.
The present invention has better snow performance.

More specifically, in the present invention, in order to ensure good snow performance due to the above-mentioned curve, the depth of the curve must be 60% or more of the main groove depth. Moreover, it is necessary that the curve of such depth has a length 11 to b from the far end to the main groove. If the above-mentioned length l is less than 1m+m, it will not be possible to achieve the above-mentioned snow performance, and if it exceeds 1mm, even if the snow performance is good, the block rigidity will be reduced and it will not be possible to achieve good dry performance. You will not be able to demonstrate your performance.

Further, in the present invention, the length l! excluding the end region communicating with the main groove is 1! In regions 3c and 4c, it is necessary to make the average depths dz and av of the curves defined by the following formulas shallow to 50% or less of the main groove depth.

ΣΔd·Δl In this way, by reducing the depth of the region excluding the curved end, the rigidity of the block as a whole increases and good dry performance can be exhibited.

Furthermore, as described above, in the present invention, the depth of the end region of the curve connected to the main groove is increased, so that the curve remains at the block edge even in the later stages of block wear. Therefore, even in the later stages of block wear, the excellent snow performance and dry performance described above can be effectively maintained.

〔Example〕

Tire A of the present invention has the same tire size of 185/70 R1385Q and has a block pattern as shown in FIG. 2, but the cross-sectional shape of the curve is as shown in FIG. 4, and tire A of the invention as shown in FIG. Conventional tires B were manufactured respectively. In both cases, the main groove depth is llnm.

The 100% modulus of the rubber used for both tires A and B at -20°C is 30 kg.
/cJ of the following rubber composition was used.

Composition of tread rubber (expressed in parts by weight) Natural rubber (R3S#4)? 0.00BR (
Nipol 1441) 41.25 Zinc white 5.00 Stearic acid
3.00 Santofl
x 13) 2. OO Microcrystalline Wax 2.00 Carbon Blank N339
75.00 Sebacic acid dioctyl ester 28.7
5N-oxydiethylene-2-benzodiazolylsulfenamide 1.10 sulfur
2. OO Furthermore, in the tire A of the present invention, in the center block 4 in FIG. 4, the length of the end region 4s of the curve is 3 mm, the depth is 1 mm, and the average depth of the intermediate region 4c is 5.51. , and in the shoulder block 3, the length of the end region 3s of the curve is 3 cm.
, the depth is 1 mm, and the average depth of the intermediate region 3C is 4.
The length was set to 5 mm.

Furthermore, in the conventional tire B, the center block 4 and shoulder block 3 in FIG. 5 have the same shape and have the dimensions as shown in the figure.

For the above tires A and B, actual vehicle tests were conducted using a 1800cc FF vehicle as a test vehicle, and the results were as follows: dry performance (feeling point) when new, snow performance (feeling point) when new, and snow performance when 50% worn. (feeling point) and circumferential step wear (visual judgment) were evaluated.

The feeling score at this time is the result of grading the feeling using a 10-point system by 10 test drivers, and it is generally considered that a score of 7 or higher is good.

The evaluation results from the above tests are as shown in the table below, and the tire A of the present invention has slightly better snow performance when new than the conventional tire B. In particular, the performance when worn out by 50% is very good, and it is It was found that it exhibited excellent snow and dry performance.

〔Effect of the invention〕

As mentioned above, according to the snow and ice road tire of the present invention, the 100% modulus of the tread rubber at 20°C is 32 kg.
/c++ as below, and the tread surface is made into a block basic pattern, and the depth at the end region where the curve provided in the block of that pattern connects to the main groove is increased, while the groove depth in other parts is decreased. By making it shallower to maintain block rigidity, it is possible to improve snow performance while preventing deterioration of dry performance and circumferential step wear. Moreover, this excellent performance can be effectively maintained until the end of wear of the block.

[Brief explanation of the drawing]

FIG. 1 is a view along arrow I-1 in FIG. 2, showing a tread cross section of a tire for snowy and icy roads according to an embodiment of the present invention. FIG. 2 is a plan view of the tread surface of the same snow and ice road tire, FIGS. 3 and 4 are sectional views corresponding to FIG. 1 of tires according to other embodiments, and FIG. 5 is a tread surface of the conventional tire. FIG. 3 is a sectional view corresponding to the figure. 1...Main groove, 2...Minor groove, 3, 4...Block, 5...Curve.

Claims (1)

[Claims] 100% modulus at -20℃ is 32kg/cm
The tread portion is made of rubber of ^2 or less, and a block basic pattern is formed on the tread surface from a plurality of main grooves extending in the tire circumferential direction and minor grooves that cross the tire circumferential direction, and each block has a tire circumferential direction. A curve having at least one end communicating with the main groove is provided, and the depth of the curve in a length range of 1 to 1 mm from the communicating end to the main groove is 60% or more of the groove depth of the main groove, A tire for snowy and icy roads, characterized in that the average depth of the other parts is 50% or less of the groove depth of the main groove.