JP3706227B2 - Vehicle tire with sipes - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle tire provided with a sipe extending in the circumferential direction at least on a shoulder block.
[0002]
[Prior art]
Conventionally, a sipe is provided in a vehicle tire, for example, a heavy-duty pneumatic tire (snow tire), in order to improve skid resistance, wandering performance, and the like when traveling on icy and snowy roads. That is, as shown in FIG. 4, this type of tire T includes a large number of land portions, that is, blocks 14 and 15 that are partitioned by a main groove 12 extending in the circumferential direction and a sub-groove 13 extending in the axial direction in the tread portion 11. Each block 14, 15 has a tread pattern, and an axial sipe 16 (horizontal narrow groove) is provided, and a shoulder block 15 on both ends in the axial direction of the tread portion 11 has a sipe 17 (vertical narrow). Groove).
[0003]
As shown in FIG. 5, the groove depth D <b> 3 of the axial sipe 17 is substantially the same as the groove depth of the sub-groove 13.
The groove bottoms of the main groove 12 and the sub-groove 13 are chamfered, but the sipe 17 is not chamfered.
[0004]
[Problems to be solved by the invention]
By the way, in the said prior art, if air is put in into a tire, a tire will swell and the circumferential direction sipe 17 space | interval (groove width) of the shoulder block 15 will spread. Therefore, if cornering is performed during traveling on the road, the wear of the blocks 14 and 15 becomes severe. Further, as the tire rotates (in the direction indicated by the arrow A in FIGS. 2 and 3), the first landing side (stepping side) 18 of each block 14, 15 moves to the kicking side 19 with the sub-groove 13 groove bottom as a fulcrum axis L The crack 15 is generated in the block 15 with the inclination and the groove bottom corner of the circumferential sipe 17 as a base point P.
[0005]
As a method of preventing this crack K, it is conceivable to chamfer the groove bottom of the sipe 17, but there is a problem that the chamfering process is difficult, and it takes a lot of time and costs.
The present invention has been made in view of the actual situation as described above. The object of the present invention is to prevent the occurrence of cracks at the groove bottom of the circumferential sipe and to fully demonstrate its function and improve durability. It is an object of the present invention to provide a vehicle tire having a sipe capable of achieving the above.
[0006]
[Means for Solving the Problems]
The present invention, in order to achieve the purpose of the pre-mentioned, takes the following technical means.
That is, according to the present invention , two parallel circumferential sipes are formed on the shoulder block located in the shoulder portion, and two parallel circumferential sipes are formed on the block on the tire equator line side from the shoulder block. The groove depth of each circumferential sipe is shallower than the groove depth of the auxiliary groove extending in the axial direction dividing each block in the circumferential direction, and the circumferential sipe of the block on the tire equator line side than the shoulder block is set. The groove width is made wider than the groove width of the circumferential sipe of the shoulder block .
[0007]
By adopting such a configuration, the groove bottom of the circumferential sipe is closer to the tread contact surface than the auxiliary groove bottom that is the axis of tilting fulcrum of each block during tire rotation. The stress concentration due to the tilting of each block can be avoided, and the occurrence of cracks at the groove bottom of the circumferential sipe is prevented.
In the present invention, since the difference between the groove depth of the circumferential sipe and the groove depth of the sub-groove is 3 mm or more, there is no influence of the block tilting stress on the groove bottom of the circumferential sipe, and cracks may occur. Disappears. If the difference between the groove depths is less than 3 mm, it is difficult to avoid the influence of block tilt stress.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a development view showing an example of a tread pattern of a heavy-duty pneumatic tire T according to the present invention, and an example of a tire equator line OO is omitted. The tread portion 1 of the tire T includes a plurality of main grooves 2 extending in the circumferential direction parallel to the tire equator line OO, and a plurality of sub grooves 3 extending in the tire axial direction and crossing the main grooves 2. Thus, a large number of blocks 4A and 4B (land portions) are formed to form a block pattern. Here, the block 4B located at the shoulder portion of the tire T is hereinafter referred to as a shoulder block.
[0009]
The block 4A and the shoulder block 4B are provided with a plurality of axial sipes 5 and circumferential sipes 6A and 6B. As shown in FIGS. 2 and 3, the groove depth D1 of the main groove 2 is deeper than the groove depth D2 of the sub-groove 3, and the grooves of the sipes 5, 6A, 6B. The depth is made shallower than the groove depth D2 of the sub-groove 3. The difference H between the groove depth D3 of the circumferential sipes 6A and 6B and the groove depth D2 of the auxiliary groove 3 is preferably 3 mm or more.
By setting the difference H between the groove depths D2 and D3 to be 3 mm or more, the groove bottoms of the circumferential sipes 6A and 6B are the sub-grooves that are the tilting fulcrum axis L of the blocks 4A and 4B when the tire T rotates. 3 mm or more away from the groove bottom 3A on the tread contact surface side.
[0010]
Therefore, when the tire T rotates in the direction indicated by the arrow A in FIG. 2, each block 4A, 4B has the auxiliary groove bottom 3A on the first arrival (stepping) side 7, that is, the tilting fulcrum axis L, as a fulcrum. Since the groove bottoms of the circumferential sipe 6A, 6B are located away from the fulcrum axis L where the block tilt stress acts intensively (indicated by arrows B in FIGS. 2 and 3), Stress does not concentrate on the groove bottoms of the sipes 6A and 6B, and there is no risk of cracks.
In the block pattern illustrated in FIG. 1, the sipe 6A groove width on the equator line OO side is the groove width of the shoulder block 4B side sipe 6B. Wider than. However, the circumferential sipes 6A and 6B can have a waveform other than a straight shape, a broken line (zigzag) shape, or the like, and are not limited to the illustrated block pattern.
[0011]
Further, it is natural that the groove bottom of each sipe 5, 6A, 6B is preferably processed with a curved surface R. Further, the difference between the groove bottom 3A of the auxiliary groove 3 and the groove bottom of the circumferential sipe 6A, 6B. A larger H is better for preventing the occurrence of cracks, but should be set appropriately in relation to each performance on icy and snowy roads.
The present invention is not limited to the above embodiment, and for example, a tread pattern in which a circumferential sipe is provided only on a shoulder block, and various patterns in which the circumferential sipe is arranged at a desired position. Can be developed.
[0012]
【The invention's effect】
As described above in detail, according to the present invention, by making the groove depth of the circumferential sipe shallower than the groove depth of the auxiliary groove extending in the axial direction, it is possible to prevent the occurrence of cracks at the groove bottom of the circumferential sipe, It greatly contributes to the development of tread patterns as well as improving the durability of sipe in the circumferential direction.
[Brief description of the drawings]
FIG. 1 is a development view showing an example of a tread pattern of a heavy duty pneumatic tire according to the present invention.
FIG. 2 is a partially broken perspective view showing a main part of one embodiment of the present invention.
FIG. 3 is a cross-sectional view taken along line AA in FIG.
FIG. 4 is a partially omitted development view showing an example of a conventional tread pattern.
FIG. 5 is an enlarged perspective view of a BB cross section of FIG. 4;
[Explanation of symbols]
1 Tread 2 Main groove 3 Sub groove 3A Sub groove bottom 4A Block 4B Shoulder blocks 6A, 6B Circumferential sipe D2 Sub groove depth D3 Circumferential sipe groove depth H Difference in groove depth

Claims (2)

Two parallel circumferential sipes (6B) are formed on the shoulder block (4B) located in the shoulder portion, and the block (4A) on the tire equator line (OO) side of the shoulder block (4B) is formed. Two parallel circumferential sipes (6A) are formed, and the groove depth (D3) of each circumferential sipes (6A, 6B) is set in the axial direction dividing each block (4A, 4B) in the circumferential direction. The groove width of the circumferential sipe (6A) of the block (4A) on the tire equator line (OO) side of the shoulder block (4B) is made shallower than the groove depth (D2) of the extending auxiliary groove (3). A tire for a vehicle having a sipe, characterized in that is made wider than the groove width of the circumferential sipe (6B) of the shoulder block (4B) . The sipe according to claim 1, wherein the difference between the groove depth (D3) of each sipe ( 6A, 6B) and the groove depth (D2) of the sub-groove (3) is 3 mm or more. A vehicle tire.

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