JPH082215A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To make improvements in an antiskid property without lowering icy road performance such as driving and braking capabilities on an intrinsic icy road surface on the basis of a block pattern. CONSTITUTION:This is a pneumatic tire that has formed a block pattern consisting of plural pieces of block lines comparted by plural pieces of main grooves 1 in the tire circumferential direction and plural pieces of sub-grooves 2 in the tire width direction being crossed with the former on the tread surface. A block line consisting of a thin block 4 with tire circumferential length L1 being longer than the mean pitch of the block lines B and B' adjoining to both the symmetrical sides or a thin rib 14 continuing in the tire circumferential direction is set up in at least one piece of the main grooves in an area of less than 0.4 times to tread developing width W from a tread center C to the tire width direction, and then width W1 of the thin width block 4 or the thin width rib 14 is set to be 0.01 to 0.05 times over the tread expansion width W.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a pneumatic tire,
In particular, the present invention relates to a studless pneumatic tire having improved skid resistance on ice and snow roads.

[0002]

2. Description of the Related Art A block pattern having an excellent edge effect is generally adopted in a pneumatic tire for ice and snow roads. However, when a vehicle equipped with this pneumatic tire runs on an ice / snow road surface while cornering or on an inclined ice / snow road surface, there is tire skidding.

Conventionally, as a means for solving the problem of skidding, there is known a method in which each block forming a block pattern is provided with a sipe (calf) in the tire circumferential direction and the skid is suppressed by its edge effect. . However, as the water film on the ice and snow road surface increases with the recent warming of the weather in recent years, skidding on the ice and snow road surface has become more likely to occur, and as described above, the tire circumference on the block has become more likely to occur. It is becoming difficult to sufficiently solve the problem of skidding simply by providing a direction sipe (calf).

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to improve skid resistance without deteriorating the original driving and braking characteristics (hereinafter referred to as ice and snow road performance) on an ice and snow road surface based on a block pattern. To provide a pneumatic tire.

[0005]

According to the present invention, which achieves the above object, a plurality of main grooves extending in the tire circumferential direction and a plurality of auxiliary grooves in the tire width direction intersecting with the main grooves are formed on a tread surface. In a pneumatic tire provided with a block pattern composed of a plurality of block rows, at least one of the main grooves in the region of 0.4 times or less of the tread development width W in the tire width direction from the tread center has its left and right sides. A block row composed of narrow blocks having a length in the tire circumferential direction longer than the average pitch of adjacent block rows on both sides or a narrow rib continuous in the tire circumferential direction is arranged, and the width of the narrow block or narrow rib. W ₁ is 0.01 to 0.
It is characterized in that it is magnified 05 times.

As described above, by arranging a block row of narrow blocks or a continuous narrow rib longer than the average pitch of the block rows on the left and right sides in the main groove located in the tread center region of the tread surface. It is possible to increase the edge effect on the lateral force of these narrow blocks or narrow ribs and improve the skid resistance without deteriorating the original ice and snow road performance of the block pattern.

The present invention will be specifically described below with reference to the drawings. FIG. 1 is a tread pattern of a pneumatic tire (studless tire) according to an embodiment of the present invention.
The tread surface is provided with six linear main grooves 1 extending in the tire circumferential direction and a plurality of tire width direction sub-grooves 2 intersecting with the main grooves 1, and a large number of blocks 3 divided into these. A block pattern composed of seven block rows is formed by. Each block 3 is provided with one sipe 5 that crosses the tire width direction,
The edge effects are used to improve the ice and snow road performance of driving and braking.

A region (tread center region) from the tread center C to a tread development width W of 0.4 W or less.
Then, in the two main grooves 1 arranged on both left and right sides of the block row of the tread center, the narrow blocks 4 are intermittently arranged at predetermined intervals, respectively.
B'is formed. The narrow block 4 is shown in FIGS.
As shown in, the tire circumferential length L ₁ is formed to be larger than the average pitch of the block rows B and B ′ that are adjacent to each other on the left and right sides. That is, the tire circumferential length L ₁ of the narrow block 4 is the sum (L ₂ + L ₃ ) of the tire circumferential length L _{2 of} the block 3 and the groove width L ₃ of the sub-groove 2 adjacent thereto.
It is larger than the average of all rounds. This narrow block 4 has a longer tire circumferential length L ₁ ,
The edge effect on the lateral force can be increased. The narrow block 4 may be a narrow rib 14 continuous in the tire circumferential direction as in the embodiment shown in FIG.

Further, the width W ₁ of the narrow block 4 is preferably 0.01 to 0.05 times the developed width W of the tread. By thus setting the width W ₁ of the narrow block 4 to be 0.01 W or more, the block rigidity against the lateral force of the narrow block 4 is increased, which can contribute to the side slip suppressing effect. On the other hand, if the width W ₁ is larger than 0.05 W, the main groove 1
The groove space of is too narrow, which adversely affects drainage.

When the tire provided with the block pattern described above is subjected to a centrifugal force by cornering on an icy and snowy road surface, as shown in FIG. 4, the block 3 and the narrow block 4 are changed from a state indicated by a dashed line to a solid line. The edges e and E on the side of the lateral force F give the extreme pressure to the road surface R and generate a strong braking reaction force. That is, the side slip of the tire is suppressed by these edge effects.

In the above-mentioned tread pattern, the narrow block 4 is provided in the tread center region, that is, the tread center C in the tire width direction with a tread development width W of 0.4.
The main groove 1 located in the tread center area within twice the width is that the outside of the tread center area is often in a non-grounded state during cornering, so if it is placed outside this tread center area, it will be narrow. Block 4
This is because the edge effect due to cannot be effectively exhibited.

Further, the groove widths W ₂ and W ₃ of the narrow block 4 and the left and right block rows B and B'are 0.1 to 0.6 of the groove depths h ₁ and h _{2 on} the respective sides. It is better to double (see Figure 3). These groove widths W ₂ and W ₃ are groove depths h ₁ and h ₂
If it is smaller than 0.1 times, the effect of suppressing the collapse of the narrow block 4 by the block 3 is weakened, and if larger than 0.6 times, the drainage effect of the main groove 1 is reduced.

The width and depth of the main groove and the number of sipes may be the same as those formed on the tread of a normal studless tire, and are not particularly limited.

[0014]

EXAMPLE The tire size, tread pattern, tread development width W, block length L ₂ and sub-groove width L ₃ are the same as described below, and the tire circumferential length L _{1 of} the narrow block Position of the width block from the tread center C (magnification to the tread development width W) and its width W ₁
The tires of the present invention 1 to 1 are different from each other as shown in Table 1.
4, Comparative tires 1 to 7 were manufactured.

For comparison, a conventional tire having the same structure as the tire 1 of the present invention was manufactured except that the narrow block was not provided. For these 12 types of tires,
The performance on ice, the performance on snow, the skid resistance on ice and the skid resistance on snow were measured by the following measurement methods, and the results are shown in Table 1.

Tire size: 1100R20
14PR tread pattern: Fig tread width (W): the length of 246mm Block L _2: the width of 24mm minor groove L _3: pitch length of 5.5mm blocks (average pitch): 29.5 mm
(24 mm + 5.5 mm) Performance on ice and snow : According to the method defined in JASO C-606, a rim was assembled on a 20 x 7.50 V rim, and a test tire filled with air pressure of 7.25 kgf / cm ² was used. It is installed on a vehicle with a displacement of about 16900 cc, and the load is 2750 kg on the front wheels and 2400 kg on the rear wheels.
The braking distance when sudden braking was applied was measured from the speed.

The evaluation was carried out using the reciprocal of the braking distance, and was expressed as an index with the measured value of the conventional tire being 100. The larger this index value, the better the performance on ice and snow. Anti-skidding performance on ice and snow: 10 km on a road surface with an inclination angle of 3 ° in the above method of measuring the performance on ice and snow
Braking was performed from the speed of / h, and the amount of slippage of the vehicle in the lateral direction was measured. The evaluation was carried out using the reciprocal of the amount of slip, and was expressed as an index with the measured value of the conventional tire being 100. The larger this index value, the better the skid resistance on ice and snow.

[0018]

[Table 1]

From Table 1, the tires 1 to 4 of the present invention have improved skid resistance on ice and snow while maintaining the same performance on ice and snow as the conventional tires, respectively, while the tires for comparison 1 to 4 No. 2 has neither improved on ice and snow performance nor anti-skid performance as compared with the conventional tire, and Comparative tires 3 and 5 have a small effect of improving anti-skid performance. Further, it can be seen that the comparative tires 4 and 6 have improved skid resistance, but have poor performance on ice and snow.

[0020]

According to the present invention, in a pneumatic tire having a block pattern formed on a tread surface, in one or more main grooves arranged in the tread center region, the average of the block rows adjacent to the left and right sides of the main groove is averaged. By providing the narrow blocks or the narrow ribs longer than the pitch, the edge effect against the lateral force can be increased and the skid can be suppressed. Moreover, these narrow blocks and narrow ribs do not deteriorate the ice-snow road performance such as the original driving and braking properties of the block pattern.

[Brief description of drawings]

FIG. 1 is a plan view showing a tread pattern of a pneumatic tire according to an embodiment of the present invention.

FIG. 2 is a partially enlarged plan view of FIG.

3 is a cross-sectional view taken along the line YY of FIG.

FIG. 4 is a diagram showing a deformation state of a block due to a lateral force of a tread portion of a tire of the present invention.

FIG. 5 is a plan view showing a block pattern of another embodiment of the tire of the present invention.

[Explanation of symbols]

 1 Main Groove 2 Sub Groove 3 Block 4 Narrow Block 5 Sipe 14 Narrow Rib B, B'Narrow Block Row

Claims (2)

[Claims] 1. A tread surface is provided with a plurality of main grooves extending in the tire circumferential direction and a plurality of sub-grooves in the tire width direction that intersect the main grooves to form a block pattern composed of a plurality of block rows. In a pneumatic tire that has been used, the tread expansion width W in the tire width direction from the tread center
At least one of the main grooves in the area of 0.4 times or less of the block row or a tire circumferential direction composed of narrow blocks having a tire circumferential length that is longer than the average pitch of adjacent block rows on the left and right sides thereof. Place a continuous narrow rib on the
A pneumatic tire in which the width W _{1 of the} narrow block or narrow rib is 0.01 to 0.05 times the developed width W of the tread. 2. The groove width between the narrow block or narrow rib and the block rows on both left and right sides thereof is set to be 0.1 to the main groove depth.
The pneumatic tire according to claim 1, which is 0.6 times as large.