JPH11139114A - Pneumatic tire for icy and snowy road - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily separate a small stone bitten in a lug groove. SOLUTION: This is a pneumatic tire for an icy and snowy road in which a main groove extended to a tire circumferential direction T is provided in a tread face, in which a lug groove extended to a tire width direction is arranged to the tire circumferential direction with a prescribed pitch to form partitively a large number of blocks 4 by the main groove and the lug groove, and in which at least three sipes 5a, 5b, 5c extended to the tire width direction are provided in the respective blocks 4. The respective sipes 5a, 5b, 5c have wide width parts 5a1 , 5b2 , 5c3 extended from a block surface 4a toward a groove bottom side respectively. In the wide width parts 5a1 , 5b2 , 5c3 , depth of the part 5b2 provided in the sipe 5b in the central side is deeper than those of the parts 5a1 , 5c3 provided in the sipes 5a, 5c in the tire circumferential direction side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire for icy and snowy roads in which a sipe is provided in a block divided by a main groove and a lug groove. The present invention relates to a pneumatic tire for snowy and snowy roads.

[0002]

2. Description of the Related Art Generally, a pneumatic tire used on an icy road has a main groove extending in a tire circumferential direction on a tread surface and lug grooves extending in a tire width direction arranged at a predetermined pitch in a tire circumferential direction. A large number of blocks are defined by the main grooves and the lug grooves, and the blocks are provided with a plurality of sipes extending in the tire width direction. Conventionally, in the pneumatic tire having such a configuration, a method of setting the width of the lug groove to be relatively small and securing a large actual contact area has been adopted in order to exhibit more performance on ice.

[0003] However, when the width of the lug groove is reduced in this manner, there is a problem that stones are often bitten and it is difficult for pebbles to fall out, thereby causing cracks at the groove bottom.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic tire for icy and snowy roads, which can easily remove pebbles caught in a lug groove.

[0005]

In order to achieve the above object, the present invention provides a main groove extending in a tire circumferential direction on a tread surface, and lug grooves extending in a tire width direction are arranged at a predetermined pitch in a tire circumferential direction. A plurality of blocks are defined by the main groove and the lug grooves, and each block is provided with at least three sipes extending in the tire width direction. A wide portion extending toward the side is provided, and the width of the wide portion is greater at the central sipe than at both sides in the tire circumferential direction.

[0006] As described above, each sipe provided in the block in the tire width direction is provided with a wide portion extending from the block surface toward the groove bottom, and the depth of the wide portion is made deeper at the center portion than at both sides. When the pebbles bite into the lug grooves, in the small block section divided by the sipe, the small block section facing the deep wide section is deformed along the wide section to the bottom side. As a result, the reaction force against the pebbles acts obliquely outward, and pushes out the pebbles that bite. Therefore,
Even if the lug groove is caught in the stone, it is possible to make it easier for the clogged pebbles to escape due to the discharging effect of the wide portion having a changed depth.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be specifically described below with reference to the embodiment shown in the drawings. FIG. 1 shows an example of a main part of a tread surface of a pneumatic tire for icy and snowy roads according to the present invention. The tread surface 1 is provided with a plurality of main grooves 2 extending along the tire circumferential direction T, and lug grooves 3 extending along the tire width direction are arranged at a predetermined pitch along the tire circumferential direction T. A large number of blocks 4 are defined by the main groove 2 and the lug groove 3. The lug groove 3 is set relatively narrow (the groove width is 5 to 8 mm) with respect to the lug groove width of the lug pattern tire (summer) 10 to 20 mm. I try to demonstrate the performance.

On the surface 4a of each block 4, three sipes 5a, 5 extending straight in the tire width direction are provided.
b, 5c are formed so as to communicate with the main grooves 2 on both sides. Each sipe 5a, 5b, 5c is, as shown in FIG.
Wide portions 5a ₁ , 5b ₂ , and 5c ₃ extend from the block surface 4a to the groove bottom side with substantially the same width, respectively. The wide portions 5a ₁ , 5b ₂ , 5c ₃ are deeper at the central sipe 5b ₂ than at the sipe 5a, 5c on both sides in the tire circumferential direction.

As described above, the wide portions 5 having the groove widths larger than the sipe are formed on the sipes 5a, 5b, 5c from the block surface 4a.
a ₁ , 5b ₂ , 5c ₃ are provided, and the wide portions 5a ₁ , 5c
In order to make the depths of b ₂ and 5c ₃ deeper on the center side and shallower on both sides, as shown in FIG. 3, the deep wide part 5b ₂ is deeper on the bottom side due to the pebbles s that bite into the lug groove 3. As a result, a force pushing the pebbles s in a direction obliquely outwardly acts on the bite s. The spitting effect of pushing out the pebbles s makes it easy to remove stones. Therefore, it is possible to suppress cracks at the bottom of the groove, which are caused by the pebbles that have been bitten.

In the present invention, the sipes 5a, 5b, 5c
Of the lug groove 3 with respect to the groove depth GD of the lug groove 3.
It can be in the range of 5 GD to 1.0 GD. In contrast, as the depth d ₂ of the wide portions 5b ₂ of the central portion, it is preferable in the range of 0.5GD~1.0GD respect groove depth GD of the lug groove 3. Depth d of wide portions 5a ₁ and 5c ₃ on both sides
_1, the d _3, 50% with respect to the wide portion of 5b ₂ depth d ₂
Preferably, the depth is about 80%.

[0011] sipes 5a, 0.5mm 5b, 0.5mm~1mm as the width w of 5c, the wide portion 5a _1, 5b _2, 5c ₃ sipes 5a is a width w ', 5b, than the width w of 5c It is better to be larger than this and smaller than 2 mm. Wide portion 5a _1, 5
As shown in FIG. ₂ , b ₂ and 5c ₃ have a shape in which the width is increased on both the left and right sides with respect to the sipe portion having a small inner width.
As the wide portion 5a ₁ shown in, whereas it may be a shape in which width increases only on the side.

In the above embodiment, the number of sipes is three. However, the number of sipes may be more than three, depending on the size of the block, or at least three. . In the case of providing five or more,
It is preferable that the depth is increased as the width of the wide portion on the center side increases. Although the upper limit varies depending on the size of the block, a maximum of 7 tires / pneumatic tire for snowy roads is generally used.
It can be one block.

According to the present invention, as shown in FIGS. 1 and 2, a convex shape extending from the block surface 4a to the groove bottom is provided on the front and rear wall surfaces 4b and 4c of each block 4 facing the lug groove 3 in the tire circumferential direction. Preferably, a protector 6 is provided. The width Y of the protector 6 is 0.4 W to 0.6 W with respect to the width W of the block wall on which the protector 6 is provided.
And the protrusion amount h can be set to 1 mm or more and 0.25 times or less of the average groove width of the facing lug grooves 3.
By projecting such a protector 6 on the block wall surface, it is possible to make it difficult for small stones to enter the lug groove 3, so that the occurrence of stone biting can be suppressed.

In the above embodiment, the protector 6 is provided so as to face the center of the wall surfaces 4b and 4c in the width direction. Instead, as shown in FIG.
It may be provided so as to be offset to the left and right end portions in the width direction of b and 4c. Further, the sipe may be a zigzag sipe as shown in FIG. 5 instead of the linear sipe described above.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The tire size is common to 185R148PR, and the three sipes provided in each block have wide portions extending from the block surface toward the groove bottom, and the depth of the wide portion is determined in the tire circumferential direction. The tire of the present invention having the block pattern shown in FIG. 1 in which the sipe at the center portion was deeper than the sipe at both sides, and a conventional tire having no wide portion in the tire of the present invention were produced.

Each of these test tires was rim size 14 × 5
Attach it to the 1 / 2JJ rim and set the air pressure to 450kPa
Mounted on a 000cc vehicle, and under the following measurement conditions,
When the stone bite generation evaluation test was performed, the results shown in Table 1 were obtained. Stone Biting Occurrence Evaluation Test Pebbles having a size of about 7 mm were evenly spread on a flat asphalt pavement road, and the vehicle was run for 50 m on an evaluation road surface. The result was evaluated by an index value with the conventional tire being 100. The smaller the value, the less occurrence of stone biting.

[0017]

[Table 1]

As is clear from Table 1, the tire of the present invention has a low frequency of stone biting, and it is easy to get rid of the bitten pebbles.

[0019]

As described above, according to the present invention, in a pneumatic tire for icy and snowy roads provided with at least three sipes extending in the tire width direction on a block, each sipe extends from the block surface toward the groove bottom side. The sipe on the center side is deeper than the sipe on both sides in the circumferential direction of the tire. Can be improved.

[Brief description of the drawings]

FIG. 1 is a development view of a main portion of a tread surface showing an example of a pneumatic tire for icy and snowy roads according to the present invention.

FIG. 2 is an enlarged sectional view taken on line AA of FIG. 1;

FIG. 3 is an enlarged sectional view showing the operation of the present invention.

FIG. 4 is an enlarged sectional view of a main part showing another example of a sipe having a wide portion in the pneumatic tire for icy and snowy roads of the present invention.

FIG. 5 is an enlarged plan view of a block showing another example of the pneumatic tire for icy and snowy roads according to the present invention.

[Explanation of symbols]

1 tread surface 2 main groove 3 lug grooves 4 blocks 4a surface 4b, 4c walls 5a, 5b, 5c sipes 5a _1, 5b _2, 5c ₃
Wide portion 6 protectors GD lug groove depth T tire circumferential direction W the width d 1 of the block wall _surface, d _2, d ₃ wide portion of the depth h protector protrusion amount s pebbles w width of w 'wide portion of the sipe

Claims (3)

[Claims] 1. A main groove extending in a tire circumferential direction is provided on a tread surface, and lug grooves extending in a tire width direction are arranged at a predetermined pitch in a tire circumferential direction, and a large number of blocks are defined by the main groove and the lug grooves. In a pneumatic tire for icy and snowy roads formed and provided with at least three sipes extending in the tire width direction in each block, each sipe has a wide portion extending from the surface of the block toward the groove bottom, A pneumatic tire for snowy and snowy roads, wherein the width of the wide portion is deeper at the center sipe than at both sides in the tire circumferential direction. 2. The depth of the wide portion of the central sipe is set to 0.5 GD to 1.0 GD with respect to the depth GD of the lug groove.
The pneumatic tire for icy and snowy roads according to claim 1. 3. A convex protector extending from the block surface to the groove bottom is provided on the front and rear wall surfaces of the block facing the lug groove in the tire circumferential direction, and the width Y of the protector is provided.
The projection width h is set to 0.4 W to 0.6 W with respect to the width W of the block wall surface provided with the protector, and the protrusion amount h is set to 1 mm or more and 0.25 times or less of the average groove width of the facing lug groove. 3. The pneumatic tire for icy and snowy roads according to 2.