JPH0911712A - Pneumatic tire - Google Patents

Abstract

PURPOSE: To provide a pneumatic tire which can improve an on-ice performance while partial wear at small blocks divided by sipes is being restrained. CONSTITUTION: In the case of a pneumatic tire in which each lateral groove 3 extending in a tire width direction is provided between main grooves 2 extending, on a tread surface, in a tire peripheral direction T, and respective blocks 4 divided by the main grooves 2 and respective lateral grooves 3 are formed, and each sipe 5 extending in the tire width direction is provided at each block 4, the cross section shape of each sipe 5 at tire side viewing is formed in a doglegged shape having one bend part 5A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having a sipe provided on a block, and more particularly to a pneumatic tire capable of further improving ice performance while suppressing uneven wear caused by the sipe. Regarding

[0002]

2. Description of the Related Art Conventionally, as a method of improving braking / driving performance on ice, there is a method of providing a sipe on a block. By providing this sipe in the tire width direction of the block, the water film on the ice is removed by using the edge of the block to prevent the tire from slipping.

In order to make the sipes more effective, there is a proposal of arranging the sipes at an angle with respect to the tire radial direction (Japanese Patent Publication No. 1-30641). By selecting the inclination direction and disposing the sipes, the braking performance or the driving performance (ice performance) is further improved. However, on the other hand, the pressure becomes uneven in the ground contact surface of the small block divided by sipes, so that uneven wear occurs in the small block. Therefore, as a solution, there is a proposal to arrange the sipes in a zigzag shape along the tire radial direction.
By providing the sipes in this way, the ground pressure in the small blocks divided by the sipes is made more uniform and uneven wear in the small blocks is suppressed.
However, since the sipe has a zigzag shape, it is difficult to open the sipe when the block comes into contact with the ground, the edge effect is reduced, and the performance on ice is deteriorated.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic tire capable of further improving its performance on ice while suppressing uneven wear in small blocks divided by sipes.

[0005]

A pneumatic tire of the present invention that achieves the above object is provided with a lateral groove extending in the tire width direction between main grooves extending in the tire circumferential direction on a tread surface. In a pneumatic tire in which a block divided by is formed and a sipe extending in the tire width direction is provided in the block, the cross-sectional shape of the sipe in a tire side view is formed in a dogleg shape having one bending portion. Characterize.

By providing the sipe 5 having one bent portion and having a V-shaped cross section as described above, the road surface side wall surface of the block facing the sipe can be made into an acute angle shape, and the edge effect thereof makes the water on the ice water. Since the film can be removed and the tire slip can be suppressed, the performance on ice can be further improved. By setting the bent portion of the sipe on the tire rotation direction side, the braking performance on the ice can be improved, and by setting the bent portion of the sipe on the tire anti-rotation side, the driving performance on the ice can be improved. it can.

Moreover, since the sipes are bent in a V shape through the bent portions, the rigidity of the small blocks partitioned by the sipes in the tire radial direction is more than that of the sipes that are inclined to one side. Can also be more uniform in the middle part. Therefore, the unevenness of the ground pressure distribution in the small block is improved, and the uneven wear occurring in the small block can be suppressed.

The structure of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows an example of a pneumatic tire of the present invention, in which a tread surface 1 is provided with a plurality of main grooves 2 extending along a tire circumferential direction T, and a space between the main grooves 2 is a tire. They are connected by lateral grooves 3 extending in the width direction, and a large number of blocks 4 are defined by the main grooves 2 and the lateral grooves 3. In each block 4,
Sipe 5 extending linearly in the tire width direction is provided with both ends thereof communicating with the main groove 2, and the sipe 5 divides the block 4 into a plurality of small blocks 4A.

According to the present invention, as shown in FIG. 2, in the pneumatic tire having the above-described block 4 provided with the sipes 5, the cross-sectional shape of the sipes 5 in the tire side view has one bent portion 5A. It is formed in a V shape. The doglegged sipe 5 includes a first sipe portion 5a extending linearly from the surface of the block 4 to the bent portion 5A on one side with respect to the tire radial direction, and a first sipe portion 5a.
The sipe portion 5a is connected to the sipe portion 5A by a bent portion 5A, and is composed of a second sipe portion 5b extending in a straight line that is inclined with respect to the tire radial direction on the other side (opposite to the first sipe portion 5a). . The bent portion 5A of the sipe 5 is on the tire rotation direction R side.

By providing the block 4 with the sipe 5 having a V-shaped cross section with the bent portion 5A as the tire rotation direction side, the tire rotation side of the block 4 facing the sipe 5 (first sipe portion 5a). Since the road side wall surface (the road side wall surface of the one small block 4A) 4a can be formed into an acute angle, the edge effect thereof effectively removes the water film on the ice during braking to prevent the tire from slipping. Since it can be suppressed, the braking performance on ice can be improved.

Moreover, since the sipe 5 is bent in a dogleg shape through the bent portion 5A, the rigidity of the small block 4A partitioned by the sipe 5 in the tire radial direction is more than that in the case where the small block 4A is simply inclined to one side. Can be made more uniform in the middle portion, and thereby uneven wear that occurs in the small blocks 4A of the blocks 4 can be suppressed.
The driving performance can be secured by the edge of the other small block 4A in the same manner as in the conventional case in which sipes are provided along the tire radial direction.

In the first sipe portion 5a, the inclination angle α with respect to the tire radial direction is equal to or greater than the inclination angle β with respect to the tire radial direction of the inclined block front wall surface 4c on the rotational direction side facing the lateral groove 3. Also, it is preferable that the tilt is arranged within a range in which the tilt is increased by 5 °. The second sipe portion 5b has the same inclination angle γ with respect to the tire radial direction as the inclination angle δ with respect to the tire radial direction of the inclined block rear wall surface 4d on the side opposite to the rotation direction facing the lateral groove 3 or 5 than that. It is preferable that the tilt is arranged within a range in which the tilt is increased.

If the inclination angles α and γ are out of the above range, the small block
Braking ability on ice while suppressing uneven wear of the rack 4A
It becomes difficult to improve the performance. Depth of Sipe 5 above
The depth d is equal to or less than the depth D of the lateral groove 3 and is 6 of the depth D.
0% or more, and the depth d of the bent portion 5A₁as,
50 to 70% of the depth of the sipe 5
Good to set. Desirably, the depth d of the bent portion 5A ₁
Is 60 to 70% of the depth d of the sipe 5.

The V-shaped sipes 5 are small blocks 4
It is preferable to arrange such that the ratio of the contact surface length L in the tire circumferential direction in A to the small block bottom length L1 from the block wall surface to the sipe at the bottom position of the sipe 5 is substantially equal in each small block 4A. . In the present invention, in the above-described embodiment, the sipe 5 having a V-shaped cross section is arranged with the bent portion 5A on the tire rotation direction R side.
The sipe 5 having the above-described configuration may be provided with the bent portion 5A on the tire counter-rotational direction S side. As a result, the road surface side wall surface 4b on the tire anti-rotation direction S side of the block 4 facing the sipe 5 can be made into an acute angle, and thus uneven wear that occurs in the small block 4A of the block 4 can be suppressed in the same manner as described above. However, the edge effect can enhance the driving performance on ice. The braking performance can be ensured as in the case where the sipes are provided along the tire radial direction.

Further, according to the present invention, the sipes 5 are provided in a mixed state in which the bent portions 4A thereof have two kinds, that is, the tire rotation direction R side and the counter rotation direction S side, and the bent portions 4A are provided in each block 4. The sipes 4 may be arranged in the same direction (in the case of plural cases). By appropriately arranging the sipes 4 as necessary, both braking and driving performance can be improved.

Therefore, in the present invention, the first sipe portion 5a of the sipe 5 is provided with the front and rear wall surfaces 4 of the block 4 facing the lateral groove 3.
same as either c or 4d, or 5 more than
The second sipe portion 5b is arranged at the same angle as the other of the front and rear wall surfaces 4c and 4d of the block 4 or at an angle of 5 ° from the other, in order to increase the inclination angle α with respect to the tire radial direction within a range of °.
Within the range, the inclination angle γ with respect to the tire radial direction can be increased to be arranged in an inclined manner.

In FIGS. 1 and 2, one sipe 5 is provided at the center of each block 4, but if necessary, a plurality of sipe 5 can be provided in each block as in the prior art. Needless to say. In that case, the bottom length L1 of the small blocks located between the sipes indicates the space at the bottom position between the sipes. Further, in the above embodiment, the sipe 5 whose both ends communicate with the main groove 2 has been described. However, with respect to a sipe whose one end communicates with the main groove 2 or a sipe which is not communicated with the main groove 2 at both ends and is inside the block, However, the present invention can be preferably used.

[0018]

Example: Tire size is 265 / 70R15, main groove,
The present invention in which the lateral groove and the groove depth of the sipe are both 12.0 mm and the inclination angles β and δ of the front and rear wall surfaces of the block are 10 ° in common, and the bent portion of the sipe shown in FIG. 1 is on the tire rotation side. The tire 1 and the tire 2 of the present invention in which the bent portion of the sipe is on the tire anti-rotation side. In FIG. 1, the conventional tire 1 provided with sipes along the tire radial direction, and the tire 1 inclined only in the same direction as the first sipe portion. A conventional tire 2 provided with a sipe and a conventional tire 3 provided with a zigzag sipe having two bent portions were manufactured. The sipe inclination angles α, γ of the tire of the present invention, the sipe inclination angle of the conventional tire 2, and the zigzag sipe inclination angle of the conventional tire 3 are each 10 °.

Each of these test tires was rim size 15 ×
It is attached to the rim of 7 1 / 2J and the air pressure is 200 kPa, and it is 3
When mounted on a 000cc passenger car and evaluated on ice and uneven wear resistance under the following measurement conditions,
The results shown in Table 1 were obtained. Performance on ice 1. Braking performance on ice Measure the braking distance when braking from a speed of 40 km / h on an ice road test course with an ice temperature of -5 ° C to -8 ° C and an air temperature of -3 ° C to -5 ° C. Was evaluated with an index value of 100. The larger the value, the better the braking performance. 2. Driving performance on ice On a icy road test course with an ice temperature of -5 ° C to -8 ° C and an air temperature of -3 ° C to -5 ° C, the starting feeling when starting from a stopped state was evaluated, and the result was evaluated using conventional tire 1 as 10
The evaluation was made with an index value of 0. The larger the value, the better the driving performance. After running 10,000 km on a test road consisting of uneven wear-resistant pavement surface, the maximum wear amount and the minimum wear amount generated in a small block of the block are measured, and the difference in the wear amount is set to be 100 with the conventional tire 1 as an index. The value was evaluated. The larger the value, the better the uneven wear resistance.

[0020]

[Table 1] As is clear from Table 1, the tire of the present invention in which the cross-sectional shape of the sipe has a dogleg shape having one bending portion can suppress uneven wear occurring in the small blocks and can further improve the performance on ice. I understand.

[0021]

As described above, the present invention provides the tread surface with the lateral groove extending in the tire width direction between the main grooves extending in the tire circumferential direction, and forming a block divided by the main groove and the lateral groove. In a pneumatic tire having a sipe extending in the tire width direction in the block, since the cross-sectional shape of the sipe in a tire side view is formed in a V shape having one bending portion, it is possible to obtain a bias in a small block divided by the sipe. The performance on ice can be further improved while suppressing wear.

[Brief description of the drawings]

FIG. 1 is a development view of a main part of a tread surface of an example of a pneumatic tire of the present invention.

FIG. 2 is an enlarged sectional view taken along the line AA of FIG.

[Explanation of symbols]

1 tread surface 2 main groove 3 lateral groove 4 block 4A small block 4c front wall surface of block 4d rear wall surface of block 5 sipes 5A bent portion 5a first sipe portion 5b second sipe portion α inclination angle of first sipe portion γ second sipe Angle of section d Depth of sipe d ₁ Depth of bent portion D Depth of lateral groove R Tire rotation direction S Tire counter rotation direction T Tire circumferential direction

Claims (6)

[Claims] 1. A tread surface is provided with a lateral groove extending in the tire width direction between main grooves extending in the tire circumferential direction, a block divided by the main groove and the lateral groove is formed, and the block extends in the tire width direction. A pneumatic tire provided with a sipe, wherein the cross-sectional shape of the sipe in a side view of the tire is formed in a V shape having one bent portion. 2. The pneumatic tire according to claim 1, wherein the bent portion of the sipe is on the tire rotation direction side. 3. The pneumatic tire according to claim 1, wherein the bent portion of the sipe is on the tire anti-rotation direction side. 4. The sipes according to claim 1, wherein the sipes are provided in a mixed manner such that the bent portions thereof are on the tire rotation direction side and the tire rotation direction side, and the directions of the bent portions are the same in each block. Pneumatic tires. 5. The sipe is composed of a first sipe portion extending from a block surface to the bent portion and a second sipe portion connected to the first sipe portion at the bent portion, and the first sipe portion is formed. The same as either one of the front and rear wall surfaces of the block facing the lateral groove, or within a range of 5 ° than that, the tilt angle is increased with respect to the tire radial direction, and the tilt is arranged.
The air according to any one of claims 1 to 4, wherein the second sipe portion is arranged at the same angle as the other of the front and rear wall surfaces of the block or at an inclination angle with respect to the tire radial direction that is larger than that of the other side wall surface within a range of 5 °. Included tires. 6. The depth of the sipe is less than or equal to the depth of the lateral groove, and the depth of the bent portion is 5 with respect to the depth of the sipe.
The pneumatic tire according to claim 1, which has a depth of 0 to 70%.