JPH04110209A - Heavy-load pneumatic radial type for ice-snow road - Google Patents

Abstract

PURPOSE:To raise anti-rut-wandering and anti-side-slip on a low-friction road surface by constituting the outer edge of the outer most block in a shoulder part, by a round portion and a square portion and specifying the ratio of the circumferential length of the round portion and the circumferential length of the outer edge of the outermost block. CONSTITUTION:The outer edge of the outer most block 3A in a shoulder part 4 is constituted by a round portion 5 and a square portion 6. The round portion 5 is formed in the circumferential middle part and the square portion 6 is formed on both sides in the circumferential direction. The relation 1/2l>=l1>=1/3l is satisfied, where L1 is the circumferential length of the round portion 5 and lis the circumferential length of the outer edge. By thus regulating the length of the round portion 5, the anti-rut-wandering can be raised.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the improvement of a heavy-duty pneumatic radial tire for use on icy and snowy roads, and more specifically, the present invention relates to the improvement of a heavy-duty pneumatic radial tire for use on icy and snowy roads, and more specifically, it relates to the improvement of a heavy-duty pneumatic radial tire for use on icy and snowy roads. This invention relates to a heavy-duty pneumatic radial tire for use on icy and snowy roads.

[Conventional technology 1] Conventionally, heavy-load pneumatic radial tires for icy and snowy roads used with high internal pressure and high loads on trucks and lotus trucks,
In order to enhance the edge effect against lateral force (sliding force) on low-friction road surfaces such as frozen roads and packed snow roads, the outer edge shape of the shoulder part sh is made into a square shape S, as shown in Fig. 5 (a). .

However, in the embodiment shown in Figure 5 (a+), although the tire skidding prevention effect is recognized, the wandering performance on a low-friction road surface is poor, that is, when driving along a slope such as frozen ruts, it is difficult to change lanes or change lanes. When attempting to escape from a rut in order to avoid an obstacle, the handle tends to become detached, resulting in poor rut wandering resistance.

Therefore, it has been proposed to improve the rut wandering resistance by making the outer edge of the shoulder portion sh rounded as shown in FIG. 5(b). However, although the embodiment shown in Fig. 5 (bl) has excellent rut-wandering resistance, it still has the problem of being prone to skidding on low-friction road surfaces. In Figure fb), IQ represents the carcass layer and 11 represents the heald layer.

As described above, it has been difficult to measure the stability of rut wandering resistance and skidding resistance.

(Problems to be Solved by the Invention) The present invention has been made in order to solve the above-mentioned problems, and is directed to an icy and snowy road that is excellent in both rut wandering resistance and sideslip resistance on a low-friction road surface. The purpose of this invention is to provide a heavy-duty pneumatic radial tire for heavy-duty use.

(Means for Solving the Problems) The heavy-duty pneumatic radial tire for ice and snow roads of the present invention has a plurality of leads extending in the tire circumferential direction on the tre-nod surface,
In a tire in which a plurality of sub-grooves intersecting with these main grooves are arranged and a large number of blocks are divided by these main grooves and sub-grooves, the outer edge of the outermost block of the shoulder part is separated from the round part and the square part. and the circumferential length of the round portion is 1 with respect to the same circumferential length β of the outer edge.
/2i≧L and ≧1/3l.

In this way, in the present invention, the outer edge shape of the shoulder block is configured to include both a round shape and a square shape for each block, thereby achieving both rutting resistance and skidding resistance on low-friction road surfaces. It becomes possible to do so.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The heavy-duty pneumatic radial tire for ice and snow roads of the present invention will be described in detail below with reference to the drawings.

In FIG. 1(a), the tread surface T of the heavy-duty pneumatic radial tire for ice and snow roads of the present invention includes a plurality of main grooves 41 extending in the tire circumferential direction and a plurality of sub grooves 2 intersecting with these main grooves 1. A large number of blocks 3 are partitioned by.

As shown in FIG. 1(ta), the outer edges of the outermost blocks 3A on both shoulder portions 4 of the tread surface T serve as the ground contact edges M of the tread surface T in the width direction.

This outer edge is composed of a round part 5 and a square part 6, as shown in FIG. 15(b) and FIG. 1 tc+. W is the ground contact width.

That is, as shown in FIG. 3, on the outer edge of one block 3A in the shoulder portion 4, a round portion 5 is formed at the center in the circumferential direction, and square portions 6 are formed on both sides in the circumferential direction. A step 7 is provided between the portion 5 and the square portion 6. In Fig. 4, shoulder part 4
The outer edge of one block 3A located in
is formed.

Here, for one block 3A of the shoulder portion 4 in FIG.
The remaining length is occupied by the square part 6 (1/2 /
≧L, ≧1/3 ρ). If the length of the round portion 5 exceeds A1, skidding resistance will be insufficient, and if it is less than lAl2, rut wandering resistance will not be obtained.

In addition, in FIG. 2, the tread radius is RA, the curvature of the square portion 6 is R1, the curvature of the round portion 5 is R2,
The intersection angle between the tangent at the point of contact between the tread radius RA and the curvature R3 of the square portion 6 and the tread surface T is θ.
It is preferable that the following formulas (1) to (4) are satisfied, respectively. Note that the center of the arc of curvature R+ is on the opposite side of the center of the arc of curvature R2.

R2≦0.03RA...■ R1≧0.4RA...■ 706≦θ≦900...■ In other words, the rut wandering resistance is achieved by satisfying the above formula (■), and the above formula (■) is satisfied. The sideslip resistance can be improved accordingly.

Also, by satisfying the following formula ■, the square part 6
The edge effect works desirably, and excellent skid resistance can be obtained.

Next, the structure and effects of the heavy-duty pneumatic radial tire for ice and snow roads of the present invention will be explained in more detail with reference to Examples.

〔Example〕

A radial tire with tire size 1000 R2014PR was formed with the tread pattern shown in FIG. Nine types of tires were obtained by changing θ as shown in Table 1.

These nine types of tires were evaluated for wandering resistance and sideslip resistance by an actual vehicle feeling test under the following conditions. The results are also shown in Table 1.

1 Yul Kuyue Kuetsu: Driving at a speed of 20km/h on a frozen icy road,
Evaluate the ease of overcoming the rut and escaping using a 3-point system (the higher the number, the better).

R-member J-up: An ice circuit with a radius of 30 meters at an initial speed of 10 km/h.
Gradually increase the speed from h and evaluate the index based on the 100 meter section time (the higher the index, the better).

(Left below next summer) From the above results, the heavy-duty pneumatic radial tire for icy and snowy roads of the present invention has the following advantages:
It is clear that the rut wander resistance and skid resistance are out of balance.

[Effects of the Invention] As described in detail above, in the heavy-duty pneumatic radial tire for ice and snow roads of the present invention, the outer edges of the outermost blocks of the shoulder portion are divided into round portions and square portions in one block. Since the structure includes both of the following, it is possible to improve rut wandering resistance and sideslip resistance on a low-friction road surface.

Therefore, the heavy-load pneumatic radial tire for ice and snow roads of the present invention is suitable as a pneumatic radial tire used under high load and high internal pressure, particularly as a tire for large vehicles such as trucks and lotuses.

[Brief explanation of the drawing]

FIG. 1(a) is a plan view explanatory diagram showing an example of the tread pattern of the heavy-duty pneumatic radial tire for ice and snow roads of the present invention, and FIG. 1(b) is the line A and -A2 in FIG. 1(a). 1c) is a cross-sectional view taken along the line B-B2, FIG. 2 is a meridional cross-sectional view showing details of the shoulder section, and FIGS. 3 and 4 are blocks of the shoulder section. FIG. 5 (a) is a perspective explanatory view showing the outer edge shape of
) and (bl are perspective explanatory views showing the outer edge shape of the block of the shoulder part in a conventional heavy-duty pneumatic radial tire for ice and snow roads. T...Tread surface, ■...Main groove, 2... minor groove,
3...Block, 3A...Shoulder block, 4...Shoulder part, 5...Round part, 6...
・Square part, RA... Tire radius, R,... Square part curvature, R2... Round part curvature, l...
Circumferential length of the outer edge of the block. L, ... Circumferential length of the round part. Figure Figure Rose Figure (a) Figure (b)

Claims (1)

[Claims] A plurality of main grooves extending in the tire circumferential direction on the tread surface,
In a tire in which a plurality of sub-grooves intersecting with these main grooves are arranged and a large number of blocks are partitioned by these main grooves and sub-grooves, the outer edge of the outermost block of the shoulder part is composed of a round part and a square part. The circumferential length L_1 of the round portion is 1 relative to the circumferential length l of the outer edge.
/2l≧L_1≧1/3l Heavy-load pneumatic radial tire for ice and snow roads.